Semantic Technologies

In recent years the Semantic Web has emerged as one of the most essential achievements for the future of the World Wide Web (WWW). Semantic Web technology extends the WWW but also enables to improve applications which are related to other fields such as communication, information, knowledge, media, and interaction technologies. Semantic Web provides not just new technologies and tools but also new paradigms and ways of thinking, to make information processing more efficient and more structured.

Our research is focussed on the devolpment and improvement of 'semantically supported multimedia retrieval and search technologies'.

Current News
Prior Events and Activities
Research Topics
Research Team
Former Team Members
Teaching
Supervised Master Theses
Projects and Partners
In the Media
Recent Publications

Research Topics

(1) Semantic Multimedia

(2) Linked Data Engineering and Applications

(3) Semantically enhanced Information Retrieval (Semantic Search)

(4) Knowledge Mining and Ontological Engineering

(5) Semantically enriched e-Learning Applications

Job Offers

Student-Coworkers for Semantic Technologies
- Job Description English (PDF)
- Job Description German (PDF)

Research Team

Prof. Dr. Harald Sack (Senior Researcher, H-1.39, Tel.: -527)
Henning Agt-Rickauer (PhD student, H-1.40, Tel.: -515)
Christian Hentschel, M.Sc. (PhD student, H-1.38, Tel.: -540)
Dipl.-Inf. Magnus Knuth (PhD student, H-1.40, Tel.: -547)
Tabea Tietz, B.A. (Scientific coworker, H-1.40, Tel.: -548)
Dipl.-Inf. Jörg Waitelonis (PhD student, H-1.38, Tel.: -537)
Henrik Jürges (student coworker)
Fritz Meiners (student coworker)
Martin Zabel (student coworker)

Former Team Members

Dr. Olaf Hartig (PostDoc)
Dinesh Reddy, M.Sc.
Tamara Bobic, M.Sc.
Dipl.-Inf. Katarina Birghan
Bernhard Quehl, M.Sc.
Dr. Nadine Steinmetz
Dr. Haojin Yang
Dipl.-Inf. Lina Wolf
Dipl.-Dokumentar Johannes Hercher
Joscha Jäger, M.A. (internship)
Johannes Osterhoff, M.A.
Dipl.-Inf. Zalan Kramer

**Left to Right:** Nadine Steinmetz, Johannes Osterhoff, Dr. Harald Sack, Jörg Waitelonis, Christian Hentschel, Bernhard Quehl

Our group

Publications

Massive Open Online Courses und ihre Rolle in der digitalen (Hochschul-) Lehre Ebner, Martin; Staubitz, Thomas; Koschutnig-Ebner, Markus; Serth, Sebastian in Massive Open Online Courses und ihre Rolle in der digitalen (Hochschul-)Lehre (2023). (Vol. 18) 245. Verlag der Technischen Universität Graz & Verein Forum neue Medien in der Lehre Austria, Graz, Austria.

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A Comprehensive Review of Anomaly Detection in Web Logs. Majd, Mehryar; Najafi, Pejman; Alhosseini, Seyed Ali; Cheng, Feng; Meinel, Christoph (2022).

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VAMO – What Story Do You Want to Tell? Cabral, Felipe; Shah, Simran; Zhou, Zhiheng; Serth, Sebastian; Krogmann, Simon; Lötzsch, Winfried (2018).

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Guilt-by-Association: Detecting Malicious Entities via Graph Mining. Najafi, Pejman; Sapegin, Andrey; Cheng, Feng; Meinel, Christoph (2017). 88–107.

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Serving Live Multimedia for the Linked Open Data Cloud. Serth, Sebastian; Haarmann, Stephan; Faber, Lukas in Lecture Notes in Informatics, M. Eibl, M. Gaedke (reds.) (2017). (Vol. P-275) 2487–2498.

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Don’t compare Apples to Oranges - Extending GERBIL for a fine grained NEL evaluation. Waitelonis, Jörg; Jürges, Henrik; Sack, Harald (2016).

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I am a Machine, let me understand Web Media!. Knuth, Magnus; Waitelonis, Jörg; Sack, Harald in LNCS (2016). 467–475.

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Scheduling Refresh Queries for Keeping Results from a SPARQL Endpoint Up-to-Date (Extended Version). Knuth, Magnus; Hartig, Olaf; Sack, Harald in CoRR (2016). abs/1608.08130

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DBpedia Links: The Hub of Links for the Web of Data. Dojchinovski, Milan; Kontokostas, Dimitris; Rößling, Robert; Knuth, Magnus; Hellmann, Sebastian (2016).

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openSAP: Evaluating xMOOC Usage and Challenges for Scalable and Open Enterprise Education. Renz, Jan; Schwerer, Florian; Meinel, Christoph (2016).

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Fine tuning CNNS with scarce training data - Adapting imagenet to art epoch classification. Hentschel, Christian; Wiradarma, Timur Pratama; Sack, Harald (2016). 3693–3697.

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Joint proceedings of the 2nd Workshop on Managing the Evolution and Preservation of the Data Web (MEPDaW 2016) and the 3rd Workshop on Linked Data Quality (LDQ 2016) Debattista, Jeremy; Fernández, Javier D.; Knuth, Magnus; Kontokostas, Dimitris; Rula, Anisa; Umbrich, Jürgen; Zaveri, Amrapali in CEUR Workshop Proceedings (2016). CEUR.org.

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Data Integration for the Media Value Chain. Agt-Rickauer, Henning; Waitelonis, Jörg; Tietz, Tabea; Sack, Harald in 1690 (2016).

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Scheduling Refresh Queries for Keeping Results from a SPARQL Endpoint Up-to-Date. Knuth, Magnus; Hartig, Olaf; Sack, Harald (2016).

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Pre-Course Key Segment Analysis of Online Lecture Videos. Che, Xiaoyin; Staubitz, Thomas; Yang, Haojin; Meinel, Christoph (2016).

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Evaluating Query and Storage Strategies for RDF Archives. Fernández, Javier D.; Umbrich, Jürgen; Polleres, Axel; Knuth, Magnus (2016). 41–48.

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Quantitative Analysis of Art Market Using Ontologies, Named Entity Recognition and Machine Learning: A Case Study. Filipiak, Dominik; Agt-Rickauer, Henning; Hentschel, Christian; Filipowska, Agata; Sack, Harald (2016). 79–90.

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refer: a Linked Data based Text Annotation and Recommender System for Wordpress. Tietz, Tabea; Waitelonis, Jörg; Jäger, Joscha; Sack, Harald in CEUR-WS (2016). (Vol. 1690)

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Semantic Annotation and Information Visualization for Blogposts with refer. Tietz, Tabea; Jäger, Joscha; Waitelonis, Jörg; Sack, Harald (2016). (Vol. 1704) 28–40.

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Improving text recognition by distinguishing scene and overlay text Quehl, Bernhard; Yang, Haojin; Sack, Harald (2015). (Vol. 9445) 944509. SPIE.

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Adaptive E-Lecture Video Outline Extraction Based on Slides Analysis. Che, Xiaoyin; Yang, Haojin; Meinel, Christoph (2015). 59–68.

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TailR: A Platform for Preserving History on the Web of Data. Meinhardt, Paul; Knuth, Magnus; Sack, Harald A. Polleres, T. Pellegrini, S. Hellmann, J. X. Parreira (reds.) (2015). 57–64.

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Enhance Lecture Archive Search with OCR Slide Detection and In-Memory Database Technology. Malchow, Martin; Bauer, Matthias; Meinel, Christoph (2015). 176–183.

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Weitere Informationen

URNhttp://dx.doi.org/10.1109/CSE.2015.19

AbstractOn the Web there are a lot of frequently used video lecture archives which have grown up fast during the last couple of years. This fact led to a lot of lecture recordings which include knowledge for a variety of subjects. The typical way of searching these videos is by title and description. Unfortunately, not all important keywords and facts are mentioned in the title or description if they are available. Furthermore, there is no possibility to analyze how important those detected keywords are for the whole video. Another lecture archive specific virtue is that every regular university lecture is repeated yearly. Normally this will lead to duplicate lecture recordings. In search results doubling is disturbing for students when they want to watch the most recent lectures from the search result. This paper deals with the idea to resolve these problems by analyzing the recorded lecture slides with Optical Character Recognition (OCR). In addition to the name and description the OCR data will be used for a full text analysis to create an index for the lecture archive search. Furthermore, a fuzzy search is introduced. This will solve the issue of misspelled search requests and OCR detection defects. Additionally, this paper deals with the performance issues of a full text search with an in-memory database, issues in OCR detection, handling duplicate recordings of lectures repeated every year. Finally, an evaluation of the search performance in comparison with other database ideas besides the in-memory database is performed. Additionally, a user acceptability survey for the search results to increase the learning experience on lecture archives was performed. As a result, this paper shows how to handle the big amount of OCR data for a full text live search performed on an in-memory database in reasonable time. During this search a fuzzy search is performed additionally to resolve spelling mistakes and OCR detection problems. In conclusion this paper shows a solution for an enhanced video lecture archive search that supports students in online research processes and enhances their learning experience.

An Improved System For Real-Time Scene Text Recognition. Yang, Haojin; Wang, Cheng; Che, Xiaoyin; Luo, Sheng; Meinel, Christoph (2015). 657–660.

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Proceedings of the 2nd Workshop on Linked Data Quality co-located with 12th Extended Semantic Web Conference (ESWC 2015) Rula, Anisa; Zaveri, Amrapali; Knuth, Magnus; Kontokostas, Dimitris (2015). (Vol. 1376) CEUR-WS.org, Portorož, Slovenia.

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Towards Linked Data Update Notifications - Reviewing and Generalizing the sparqlPuSH approach. Knuth, Magnus; Reddy, Dinesh; Dimou, Anastasia; Vahdati, Sahar; Kastrinakis, George A. Dimou, J. van Ossenbruggen, M.-E. Vidal, M. V. Sande (reds.) (2015).

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The DBpedia Events Dataset. Knuth, Magnus; Lehmann, Jens; Kontokostas, Dimitris; Steiner, Thomas; Sack, Harald S. Villata, J. Z. Pan, M. Dragoni (reds.) (2015).

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DBpedia Commons: Structured Multimedia Metadata from the Wikimedia Commons. Vaidya, Gaurav; Kontokostas, Dimitris; Knuth, Magnus; Lehmann, Jens; Hellmann, Sebastian in Lecture Notes in Computer Science, M. Arenas, O. Corcho, E. Simperl, M. Strohmaier, M. d’Aquin, K. Srinivas, P. T. Groth, M. Dum (reds.) (2015). (Vol. 9367) 281–289.

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PatchR: A Framework for Linked Data Change Requests. Knuth, Magnus; Sack, Harald in International Journal on Semantic Web and Information Systems (IJSWIS) (2015). 11(1) 30–45.

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FRanCo - A Ground Truth Corpus for Fact Ranking Evaluation. Bobic, Tamara; Waitelonis, Joerg; Sack, Harald G. Cheng, K. Gunaratna, A. Thalhammer (reds.) (2015).

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Optimizing the Video Experience in MOOCs. Renz, Jan; Bauer, Matthias; Malchow, Martin; Staubitz, Thomas; Meinel, Christoph (2015).

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Proceedings of the 1st Workshop on Linked Data Quality (LDQ) Knuth, Magnus; Kontokostas, Dimitris; Sack, Harald in CEUR Workshop Proceedings (2014). CEUR-WS.org, Leipzig, Germany.

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Data Cleansing Consolidation with PatchR. Knuth, Magnus; Sack, Harald in Lecture Notes in Computer Science, Presutti, V., Blomqvist, E., Troncy, R., Sack, H., Papadakis, I., Tordai, A. (reds.) (2014). (8798th ed)

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Joint Proceedings of the Second International Workshop on Semantic Web Enterprise Adoption and Best Practice and Second International Workshop on Finance and Economics on the Semantic Web Co-located with 11th European Semantic Web Conference García-Crespo, Ángel; Berbís, Juan Miguel Gómez; Radzimski, Mateusz; Sánchez-Cervantes, José Luis; Coppens, Sam; Hammar, Karl; Knuth, Magnus; Neumann, Marco; Ritze, Dominique; Sande, Miel Vander in CEUR Workshop Proceedings (2014). CEUR-WS.org, Anissaras, Crete, Greece.

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A framework for improved video text detection and recognition. Yang, Haojin; Quehl, Bernhard; Sack, Harald in Multimedia tools and applications (2014). 69(1) 217–245.

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WaSABi 2014: Breakout Brainstorming Session Summary. Coppens, Sam; Hammar, Karl; Knuth, Magnus; Neumann, Marco; Ritze, Dominique; Sande, Miel Vander in CEUR Workshop Proceedings, Ángel García-Crespo, J. M. G. Berbís, M. Radzimski, J. L. Sánchez-Cervantes, S. Coppens, K. Hammar, M. Knuth, M. Neumann, D. Ritze, M. V. Sande (reds.) (2014).

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Linked Data Quality: Identifying and Tackling the Key Challenges. Knuth, Magnus; Kontokostas, Dimitris; Sack, Harald in CEUR Workshop Proceedings (2014).

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Smart Media Navigator: Visualizing Recommendations based on Linked Data. Tietz, Tabea; Waitelonis, Jörg; Jäger, Joscha; Sack, Harald (2014). 48–51.

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Linked Data Cleansing and Change Management. Knuth, Magnus in Lecture Notes in Computer Science, P. Lambrix, E. Hyvönen, E. Blomqvist, V. Presutti, G. Qi, U. Sattler, Y. Ding, C. Ghidini (reds.) (2014). (Vol. 8982) 201–208.

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openHPI: Evolution of a MOOC Platform from LMS to SOA. Totschnig, Michael; Willems, Christian; Meinel, Christoph (2013). 49–54.

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Tree-structure Outline Generation for Lecture Videos with Synchronized Slides. Che, Xiaoyin; Yang, Haojin; Meinel, Christoph (2013). 87–92.

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openHPI - a Case-Study on the Emergence of two Learning Communities. Grünewald, Franka; Mazandarani, Elnaz; Meinel, Christoph; Teusner, Ralf; Totschnig, Michael; Willems, Christian (2013).

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Lecture Video Segmentation by Automatically Analyzing the Synchronized Slides. Che, Xiaoyin; Yang, Haojin; Meinel, Christoph (2013). 345–348.

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Semantic Multimedia Information Retrieval Based on Contextual Descriptions. Steinmetz, Nadine; Sack, Harald (2013).

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Statistical Analyses of Named Entity Disambiguation Benchmarks. Steinmetz, Nadine; Knuth, Magnus; Sack, Harald (2013).

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CONTENTUS - technologies for next generation multimedia libraries. Nandzik, Jan; Litz, Berenike; Flores-Herr, Nicolas; Löhden, Aenne; Konya, Iuliu; Baum, Doris; Bergholz, André; Schönfuß, Dirk; Fey, Christian; Osterhoff, Johannes; Waitelonis, Jörg; Sack, Harald; Köhler, Ralf; Ndjiki-Nya, Patrick in Multimedia Tools and Applications (2013). 63(2) 287–329.

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Weitere Informationen

URNhttp://dx.doi.org/doi:10.1007/s11042-011-0971-2

AbstractAn ever-growing amount of digitized content urges libraries and archives to integrate new media types from a large number of origins such as publishers, record labels and film archives, into their existing collections. This is a challenging task, since the multimedia content itself as well as the associated metadata is inherently heterogeneous—the different sources lead to different data structures, data quality and trustworthiness. This paper presents the contentus approach towards an automated media processing chain for cultural heritage organizations and content holders. Our workflow allows for unattended processing from media ingest to availability thorough our search and retrieval interface. We aim to provide a set of tools for the processing of digitized print media, audio/visual, speech and musical recordings. Media specific functionalities include quality control for digitization of still image and audio/visual media and restoration of the most common quality issues encountered with these media. Furthermore, the contentus tools include modules for content analysis like segmentation of printed, audio and audio/visual media, optical character recognition (OCR), speech-to-text transcription, speaker recognition and the extraction of musical features from audio recordings, all aimed at a textual representation of information inherent within the media assets. Once the information is extracted and transcribed in textual form, media independent processing modules offer extraction and disambiguation of named entities and text classification. All contentus modules are designed to be flexibly recombined within a scalable workflow environment using cloud computing techniques. In the next step analyzed media assets can be retrieved and consumed through a search interface using all available metadata. The search engine combines Semantic Web technologies for representing relations between the media and entities such as persons, locations and organizations with a full-text approach for searching within transcribed information gathered through the preceding processing steps. The contentus unified search interface integrates text, images, audio and audio/visual content. Queries can be narrowed and expanded in an exploratory manner, search results can be refined by disambiguating entities and topics. Further, semantic relationships become not only apparent, but can also be navigated.

Linked Soccer Data. Bergmann, Tanja; Bunk, Stefan; Eschrig, Johannes; Hentschel, Christian; Knuth, Magnus; Sack, Harald; Schüler, Ricarda (2013).

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Text detection in video images using adaptive edge detection and stroke width verification. Yang, Haojin; Quehl, Bernhard; Sack, Harald (2012). 9–12.

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Open Up Cultural Heritage in Video Archives with Mediaglobe. Hentschel, Christian; Hercher, Johannes; Knuth, Magnus; Osterhoff, Johannes; Quehl, Bernhard; Sack, Harald; Steinmetz, Nadine; Waitelonis, Jörg; Yang, Haojin in Lecture Notes in Informatics (2012).

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A framework for improved video text detection and recognition. YANG, Haojin; Quehl, Bernhard; Sack, Harald in Multimedia Tools and Applications (2012). 69(1) 217–245.

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Evaluating Entity Summarization Using a Game-Based Ground Truth. Thalhammer, Andreas; Knuth, Magnus; Sack, Harald (2012).

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Text Detection in Video Images Using Adaptive Edge Detection and Stroke Width Verification. Haojin Yang, Bernhard Quehl; Sack, Harald (2012).

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DBpedia Ontology Enrichment for Inconsistency Detection. Töpper, Gerald; Knuth, Magnus; Sack, Harald (2012).

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Collaboratively Patching Linked Data. Knuth, Magnus; Hercher, Johannes; Sack, Harald (2012). 33–40.

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Cross-Dataset Learning of Visual Concepts In: Adaptive Multimedia Retrieval: User, Context, and Feedback. Hentschel, Chirstian; Sack, Harald; Steinmetz, Nadine (2012).

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A Skeleton based Binarization Approach for Video Text Recognition. Yang, Haojin; Quehl, Bernhard; Sack, Harald (2012).

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Automated Extraction of Lecture Outlines from Lecture Videos: a Hybrid Solution for Lecture Video Indexing. Yang, Haojin; Gruenewald, Franka; Meinel, Christoph (2012).

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An Automated Analysis and Indexing Framework for Lecture Video Portal. Yang, Haojin; Oehlke, Christoph; Meinel, Christoph in lecture notes in computer science (2012). 285–294.

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Towards exploratory video search using linked data. Waitelonis, Jörg; Sack, Harald in Multimedia Tools and Applications (2012). 59(2) 645–672.

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Sneak Preview? Instantly Know What To Expect In Faceted Browsing. Osterhoff, Johannes; Waitelonis, Jörg; Jäger, Joscha; Sack, Harald (2011).

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Improving Search in Tele-Lecturing: Using Folksonomies as Trigger to Query Semantic Datasets to Extract Additional Metadata. Franka Moritz, Maria Siebert; Meinel, Christoph (2011).

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Whoknows? - Evaluating Linked Data Heuristics with a Quiz that cleans up DBpedia. Waitelonis, Jörg; Ludwig, Nadine; Knuth, Magnus; Sack, Harald in International Journal of Interactive Technology and Smart Education (ITSE) (2011). 8(4) 236–248.

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Lecture Video Indexing and Analysis Using Video OCR Technology. Yang, Haojin; Sack, Harald; Meinel, Christoph in International Journal of Multimedia Processing and Technologies (JMPT) (2011). 2(4) 176–196.

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The Generation of User Interest Profiles from Semantic Quiz Games. Knuth, Magnus; Ludwig, Nadine; Wolf, Lina; Sack, Harald (2011).

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More than the Sum of its Parts: CONTENTUS -- A Semantic Multimodal Search User Interface. Waitelonis, Jörg; Osterhoff, Johannes P.; Sack, Harald in CEUR Workshop Proceedings (2011). (Vol. 694)

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WhoKnows? - Evaluating Linked Data Heuristics with a Quiz that Cleans Up DBpedia. Ludwig, Nadine; Waitelonis, Jörg; Knuth, Magnus; Sack, Harald in LNCS (2011).

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Lecture Video Indexing and Analysis Using Video OCR Technology. Yang, Haojin; Siebert, Maria; Lühne, Patrick; Sack, Harald; Meinel, Christoph (2011).

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A Solution for German Speech Recognition for Analysis and Processing of Lecture Videos. Yang, Haojin; Oehlke, Christoph; Meinel, Christoph (2011).

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Towards exploratory video search using linked data. Waitelonis, Jörg; Sack, Harald (2011). (Vol. 53) 1–28.

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WhoKnows? - Evaluating Linked Data Heuristics with a Quiz that Cleans Up DBpedia. Waitelonis, Jörg; Ludwig, Nadine; Knuth, Magnus; Sack, Harald (2011). (Vol. 8) 236–248.

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RISQ! Renowned Individuals Semantic Quiz – A Jeopardy like Quiz Game for Ranking Facts. Wolf, Lina; Knuth, Magnus; Osterhoff, Johannes; Sack, und Harald in ICPS (2011).

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Automatic Lecture Video Indexing Using Video OCR Technology. Yang, Haojin; Siebert, Maria; Lühne, Patrick; Sack, Harald; Meinel, Christoph (2011).

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Lecture video indexing and analysis using video ocr technology. Yang, Haojin; Siebert, Maria; Luhne, Patrick; Sack, Harald; Meinel, Christoph (2011). 54–61.

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Community Tagging in Tele-Teaching Environments. Grünewald, Franka; Siebert, Maria; Meinel, Christoph (2011).

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Named Entity Recognition for User-Generated Tags. Ludwig, Nadine; Sack, Harald in CS (2011).

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Unsupervised Matching of Object Models and Ontologies. Quasthoff, Matthias; Völkel, Max; Meinel, Christoph (2010). 7.

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Enabling Reputation Interoperability through Semantic Technologies. Alnemr, Rehab; Paschke, Adrian; Meinel, Christoph (2010). No.13.

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The Path is the Destination -- Enabling a New Search Paradigm with Linked Data. Waitelonis, Jörg; Knuth, Magnus; Wolf, Lina; Hercher, Johannes; Sack, Harald in CEUR Workshop Proceedings (2010). (Vol. 700)

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Distributed Recognition of Content Similarity in a Tele-Teaching Portal. Siebert, Maria; Moritz, Franka; Meinel, Christoph (2010).

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A Linked Data Web Programm Framework. Quasthoff, Matthias; Meinel, Christoph in LNCS (2010).

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Tracing the Provenance of Object-Oriented Computations on RDF Data. Quasthoff, Matthias; Meinel, Christoph in 576 (2010). paper 4.

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Exploratory Semantic Video Search with yovisto. Waitelonis, Jörg; Sack, Harald (2010). 446–447.

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Indexing German Audiovisual Heritage - SKOSification Made Easy. Hercher, Johannes; Sack, Harald (2010).

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Community Rating in the Tele-Lecturing Context. Moritz, Franka; Siebert, Maria; Meinel, Christoph (2010).

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Semantically Enabled Exploratory Video Search. Waitelonis, Jörg; Sack, Harald; Kramer, Zalan; Hercher, Johannes (2010). 8:1–8:8.

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Establishing an Expandable Architecture for a tele-Teaching Platform. Siebert, Maria; Moritz, Franka; Meinel, Christoph in ACIS (2010). 323–328.

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Realization of an Expandable Search Function for an E-Learning Web Portal. Siebert, Maria; Meinel, Christoph in ACIS (2010). 361–366.

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Use What You Have -- Yovisto Video Search Engine Takes a Semantic Turn. Waitelonis, Jörg; Ludwig, Nadine; Sack, Harald (2010).

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SEMANTISCHE SUCHE-Theorie und Praxis am Beispiel der Videosuchmaschine yovisto.com. Sack; Harald (2010). 13–25.

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Semantische Suche - Theorie und Praxis am Beispiel der Videosuchmaschine yovisto.com. Sack, Harald in Web 3.0 & Semantic Web, HMD - Praxis der Wirtschaftsinformatik, (U. Hentgartner; A. Meier, reds.) (2010). 271

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Linking the tele-TASK Video Portal to the Semantic Web. Baumann, Bert; Sack, Harald; Groß, Andreas; Meinel, Christoph (2009). (Vol. 148) 205–216.

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Can Software Developers Use Linked Data Vocabulary?. Quasthoff, Matthias; Sack, Harald; Meinel, Christoph in J.UCS Conference Proceedings Series (2009). 542–549.

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How to Simplify Building Semantic Web Applications. Quasthoff, Matthias; Sack, Harald; Meinel, Christoph in CEUR Workshop Proceedings (2009). (Vol. 524)

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Augmenting Video Search with Linked Open Data. Waitelonis, Jörg; Sack, Harald in J.UCS Conference Proceedings Series (2009). 550–558.

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Towards Exploratory Video Search Using Linked Data. Waitelonis, Jörg; Sack, Harald (2009). 540–545.

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Semantic Web Admission Free – Obtaining RDF and OWL Data from Application Source Code. Quasthoff, Matthias; Meinel, Christoph (2008).

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Automatische Erzeugung Semantischer Annotationen für Vorlesungsvideos. Repp, Stephan; Linckels, Serge; Meinel, Christoph (2008). (Vol. 132GI) 149–160.

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Who Reads and Writes the Social Web? A Security Architecture for Web 2.0 Applications. Quasthoff, Matthias; Sack, Harald; Meinel, Christoph (2008). 576–582.

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Retrieval Optimization of Pertinent Answers for NL Questions with the E-Librarian Service. Linckels, Serge; Sack, Harald; Meinel, Christoph (2007).

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Encouraging Participation in Virtual Communities - The IT-Summit Blog Case. Bross, Justus; Sack, Harald; Meinel, Christoph in Int. Journal on WWW/Internet (2007). 5(2) 113–129.

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Encouraging Participation in Virtual Communities: The "IT-summit-blog" Case. Bross, Justus; Sack, Harald; Meinel, Christoph (2007). 245–254.

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Segmentation and Annotation of Audiovisual Recordings based on Automated Speech Recognition. Repp, Stephan; Waitelonis, Jörg; Sack, Harald; Meinel, Christoph in LNCS (2007). (Vol. 4881) 620–629.

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Optimizing the Retrieval of Pertinent Answers for NL Questions with the E-Librarian Service. Linckels, Serge; Sack, Harald; Meinel, Christoph in LNCS (2007).

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Why HTTPS Is Not Enough - A Signature-Based Architecture for Trusted Content on the Social Web. Quasthoff, Matthias; Sack, Harald; Meinel, Christoph (2007). 820–824.

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Probabilistic Equivalence Checking of Multiple-Valued Functions. Dubrova, Elena; Sack, Harald in Multiple-Valued Logic and Soft Computing (2004). 10(4) 395–414.

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Adapted Variable Reordering for XOR-OBDDs. Meinel, Christoph; Sack, H. (2003). 135–144.

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VisBDD - A Webbased Visualization Framework for OBDD Algorithms. Meinel, Christoph; Sack, Harald; Schillings, Volker (2002). 385–390.

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Course Management in the Twinkle of an Eye. Meinel, Christoph; Sack, Harald; Schillings, Volker (2002). 281–283.

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A Simple Heuristic for Mod2-OBDD Minimization. Meinel, Christoph; Sack, Harald (2001). 304–309.

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Improving XOR-node Placement for Mod2-OBDD Minimzation. Meinel, Christoph; Sack, Harald (2001). 51–56.

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IDDS: An Interactive Decentralized Documentation System. Meinel, Christoph; Sack, Harald; Schillings, Volker (2001).

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Representation of Multiple-Valued Functions with Mod-p Decision Diagrams. Sack, Harald; Dubrova, Elena; Meinel, Christoph (2000). 341–348.

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Mod-p-DDs: A Data-Structure for Multiple-Valued Functions. Sack, Harald; Dubrova, Elena; Meinel, Christoph (2000). 233–238.

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Functional Extension of Decision Diagrams in Practice. Sack, Harald; Meinel, Christoph (2000). 195–196.

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A Search-Engine-Topology to Improve Document Retrieval on the Web. Roth, Uwe; Heuer, Andreas; Haffner, Ernst-Georg; Meinel, Christoph (2000). 470–475.

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Integration der Schleusentechnologie "Lock-Keeper" in moderne Sicherheitsarchitekturen. Haffner, Ernst-Georg; Engel, Thomas; Meinel, Christoph (2000).

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Probabilistic Symbolic Simulation and Verification with Mod2-OBDDs. Sack, Harald; Meinel, Christoph in Electronic Notes in Theoretical Computer Science (1999). 22 156–170.

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Projects and Partners

AV-Portal Gottfried-Leibnitz-Universität Hannover, project with Technische Informationsbibliothek Hannover (TIB)
Semantic Media Explorer (SEMEX)
The Semantic Media Explorer is a demonstrator that combines the latest media analysis processes to provides optimal access to video content.
MEDIAGLOBE Project
The aim of MEDIAGLOBE is to open and interlink heterogenouse and currently isolated information sources in media archives and broadcasting corporation. Project partners: DEFA-spektrum, Medienbildungsgesellschaft Babelsberg mbH, Blue Order GmbH
THESEUS/CONTENTUS Project
The purpose of CONTENTUS is to develop basic technologies with which to access, archive and search for multi-media cultural assets and works of art.
YOVISTO
Yovisto is a video search engine specialized in academic content. Yovisto's search index is based on the combination of automated content based video analysis with user generated collaborative annotation (collaborative tagging, discussions, and comments). In difference to traditional video search engines, Yovisto enables pinpoint access within video data by providing fine-granular, time-dependent metadata.
Semantic Games
Games with a purpose that are dedicated to create and curate semantic content.

Current News

Invited Keynote: 21.06.2013: Harald Sack "Semantic Multimedia Analysis and Search", Symposium on Future Trends in Service-Oriented Computing, HPI, Potsdam.
Invited Talk: 18.03.2013: Harald Sack "Context-driven Semantic Multimedia Search", GoPortis Conference 2013 on non-textual Information - Strategy and Innovation Beyond Text, Hannover.
Invited Talk: 21.01.2013: Harald Sack "Strukturelle und semantische Analyse audiovisueller Medien - von der automatischen Schnitterkennung zur semantischen Suche", Gastvorlesung in den Medienwissenschaften, Universität Potsdam.
Invited Talk: 09.10.2012: Harald Sack "Semantics and Media Analysis"(6th_tele_task_symposium_2012) HPI-Potsdam.
Invited Talk: 25.09.2012: Harald Sack "Summarization and Relevance of Linked Data Facts"(LSWT2012) , Leipzig.
Invited Talk: 25.09.2012: Magnus Knuth "Linked Data Cleansing" (LSWT2012) , Leipzig.
Invited Talk: 25.09.2012: Nadine Steinmetz"How to Use Suggestion Services in Semantic Applications" (LSWT2012) , Leipzig.
Invited Talk: 20.09.2012: Harald Sack "Der Weg ist das Ziel – Explorative semantische Suche" (IVDW2012) Braunschweig.
20.09.2012: Jörg Waitelonis "Widen the Peepholes! Entity-based Auto-Suggestion as a rich and yet immediate Starting Point for Exploratory Search" (IVDW2012) Braunschweig.
Invited Talk: 29.05.2012: Magnus Knuth "Semantic Web Technologies" at TMF Forum Metadata and Linked Data, Berlin.
23.05.-25.05.2012: Bernhard Quehl "A Skeleton Based Binarization Approach for Video Text Recognition" at 13th International Workshop on Image Analysis for Multimedia Interactive Services (WIAMIS2012), Dublin.
10.05.2012: Harald Sack "Medienanalyse", at the Mediaglobe concluding event, Berlin
10.05.2012: Jörg Waitelonis "Semantische Suche" at the Mediaglobe concluding event, Berlin
07.05.2012: "Neues Sucherlebnis beim Stöbern in Videoarchiven", HPI press release, Potsdam
10.05.2012: Meet us at the Mediaglobe concluding event in Berlin.
08.05.2012: Meet us at the Infomare satelite event "Lange Nacht der Suchmaschinen" in Berlin.
27.04.2012: Meet us at the CONTENTUS concluding event in Berlin.
18.04.2012: Christian Hentschel "High Performance Visual Video Analysis" at Future SOC Lab Day, Potsdam.
17.04.2012: Magnus Knuth "Colaboratively Patching Linked Data" at 2nd International Workshop on Usage Analysis and the Web of Data (USEWOD2012), Workshop at WWW 2012, Lyon.
12.04.2012: Bernhard Quehl "Text Detection in Video Images Using Adaptive Edge Detection and Stroke Width Verification" at 19th International Conference on Systems, Signals and Image Processing (IWSSIP2012).
23.03.2012: Johannes Hercher "Quo vadis nutzergenerierte Metadaten" at 2. DGI-Konferenz, Düsseldorf.
06.03.-10.03.2012: Meet us at the CeBIT Hannover, Hall 26 (H12).
13.02-15.02.2012: Meet us at the THESEUS congress in Berlin.
10.01.2012: Harald Sack Bildersuche im Netz, Interview on DRadio Wissen.
Invited Talk - 18. Jan 2012: Harald Sack, "Semantic Multimedia Analysis and Exploration", 63. Theorietag - Workshop über Algorithmen und Komplexität, Fachhochschule Brandenburg.

Prior Events and Activities

2011

Invited talk: 19.11.2011: Harald Sack, "Vom Suchen und Finden im Internet", for "Flüchtige Worte - Leben im digitalen Zeitalter" Tagung des Forum OST-WEST e.V. Potsdam, Seddiner See, Potsdam.
15.11.2011: Harald Sack, "Milliarden neuer Internetadressen - Verloren im Adressdschungel oder Raum für neue Geschäftsideen?", Keynote im Rahmen der Zukunftsdialoge, ständige Vertretung des Landes Brandenburgs beim Bund, Berlin.
Invited talk: 30.09.2011: Harald Sack, "Enabling Exploratory Video Search by Semantic Video Analysis" atLearning, Knowledge, Adaptation (LWA) 2011, Magdeburg.
19.09.2011: Harald Sack, "Suchen ist nicht immer gleich Suchen" at Corporate Semantic Web (CSW) Workshop, Xinnovations, Berlin.
Invited talk: 01.09.2011: Jörg Waitelonis, "Inhaltsbasierte Erschließung und Suche in multimedialen Objekten" at 35. Jahrestagung der Gesellschaft für Klassifikation, Frankfurt.
31.08.2011: Nadine Ludwig, "Named Entity Recognition for User-Generated Tags" at Text-based Information Retrieval (TIR) Workshop at DEXA 2011, Toulouse.
Invited talk: 20.06.2011: Harald Sack, "Semantic Search for audiovisual media" at THESEUS Thementag, Effiziente Erschließung digitaler Medien, Berlin.
16.06.2011: Harald Sack, Panel Discussion at 10th Innovative Internet Community Systems (I2CS 2011), Berlin: "Blessing or Curse for Online Communities? The Influence of Social Media, Mobile Internet and Clouds on Communities"
09.06.2011: Harald Sack / Jörg Waitelonis, "Projekt Mediaglobe im Theseus Forschungsprogram / Yovisto Akademische Videosuche", Workshop Inhaltsbasierte Erschließung und Suche in multimedialen Objekten, 100. Bibliothekartag 2011, Berlin.
Invited talk: 25.05.2011:Harald Sack, "Wie Sie schon immer finden wollten, was Sie noch nie gesucht haben", Leibniz Kolleg Potsdam, Potsdamer Naturwissenschaftliche Vorträge, Universitätscampus Golm, Potsdam.
Invited talk: 05.05.2011: Harald Sack, "Semantic Media Explorer - Neue Wege der Suche in Medienarchiven", Leipziger Semantic Web Tag 2011, Leipziger Mediencampus, 5. Mai 2011, Leipzig.
Invited talk: 22.03.2011: Johannes Hercher, "Semantische Suche im audiovisuellen Kulturerbe – Das Projekt mediaglobe", 2. I-Science Tage, March 22th, 2011, University of Applied Sciences, Potsdam.
01.-05. Mar. 2011: We present our research at CEBIT Hannover, Hall 9 (C15).
VISSW 2011, Visual Interfaces to the Social and Semantic Web, in conjunction with the International Conference on Intelligent User Interfaces (IUI 2011), Palo Alto, CA, USA, 13 Feb 2011.
Invited talk: 7. Feb. 2011: Harald Sack, "Semantik - Die nächste Herausforderungen für Anwendungen in der IT", HPI Academy, Feburary 7th, 2011, Hasso Plattner-Institute for IT Systems Engineering, Potsdam.
Invited talk: 7. Feb. 2011: Harald Sack, "Semantische Multimediasuche - CONTENTUS, MEDIAGLOBE und yovisto", Berlin Semantic Meetup, Feburary 6th, 2011, Konrad Zuse Zentrum für Informationstechnik, Freie Universität Berlin, Berlin.

2010

Invited talk: 2. Dec. 2010: Harald Sack, "Explorative und semantische Suche mit Mediaglobe", IRT-Symposium "Vom Suchen zum Finden - in multimedialen Archiven der nächsten Generation", December 1-2, 2010, Institut für Rundfunktechnik, München.
5th Int. Conference on Semantic and Digital Media Technologies (SAMT 2010), December 1-3, 2010, Saarbrücken, Germany.
Invited talk: 13. Oct. 2010: Harald Sack, "Archivierung, Analyse, Interaktion und Remix von wissenschaftlichen Online-Vorträgen", Wissenschaft auf neuer Bühne, 2. Meilensteintagung des Forschungsverbundes "Interactive Science - Interaktive Wissenschaftskommunikation über digitale Medien, Schloss Rauischgolzhausen, Justus-Liebig-Universität Gießen.
4th IEEE International Conference on Semantic Computing (ICSC 2010), September 22-24, 2010, Carnegie Mellon University, Pittsburgh, PA, USA.
Invited Talk:Harald Sack, "Semantic Search Technologies for Video Archives", Sino-German Forum on 'Digital University and Higher Education', in conjunction with 5th tele-TASK Symposium, Sept. 15-17, 2010, Bejing, China.
3rd KRDB school on 'Trends in the Web of Data' (KRDBs-2010), Brixen-Bressanone, Italy, 17-18 September 2010
9th European Workshop on Networked Knowledge Organization Systems and Services (NKOS 2010), Sep 9-10, 2010, at 14th European Conference on Digital Libraries 2010 (ECDL 2010), Glasgow, Scottland
Invited talk: 08. Sept. 2010: Harald Sack, "Semantic Web - Vom WWW zum Web of Data", Workshop 'Future Internet: Web 3.0 - Social, Service, Semantic Web' im Rahmen des 7. Fernausbildungskongresses 2010 der Bundeswehr, 7.-9. Sept. 2010, Helmut-Schmidt-Universität / Universität der Bundeswehr, Hamburg
Semantic Search Workshop (SemSearch10) at the 19th Int. World Wide Web Conference (WWW2010), 26-30 April 2010, Raleigh, NC, USA, 2010
Invited Talk: 15. Juni 2010: Harald Sack:"Linked Open Data Universe", Eröffnung FutureSOC-Lab, 5th Annual Symposium on Future Trends in Service-Oriented Computing, Hasso-Plattner-Institut für Softwaresystemtechnik, Potsdam.
Invited Talk: 26. Feb. 2010:Harald Sack:"Der Weg ist das Ziel - Explorative Videosuche jenseits des gängigen Suchparadigmas", 4. tele-TASK Symposium, Hasso-Plattner-Institut für Softwaresystemtechnik, Potsdam.

2009

International Symposium on Multimedia (ISM2009), December 14-16, 2009, San Diego
Invited Talk: 07. Dez. 2009: Harald Sack, "Das Semantic Web als kulturelles Phänomen", Impuls-Referat im Seminar "Web-Tendenzen als kulturelles Phänomen" an der FH-Potsdam, 07. Oktober 2009.
International Conference on Semantic Systems, I-SEMANTICS '09, 02.-04. September, Graz, Austia
Invited Talk: 07. Okt. 2009: Harald Sack, "Semantische Co-Annotation und Videosuche mit YOVISTO", Multimedia-Forum der DFN-Betriebstagung, 06./07. Oktober 2009, Johannesstift Berlin-Spandau.
Invited Talk: 09. Sep. 2009: Harald Sack, "Wie Sie schon immer finden wollten, was Sie noch nie gesucht haben - Paradigmenwechsel in der (Web)Suche", Keynote, 13. Verbundkonferenz des GBV, 9.-10.09.2009, Hamburg.
Summer School on Multimedia Semantics 2009, 23.-28. August, Koblenz, Germany
Open Video Conference, Metadata-Round-Table, 19.-21. June 2009, New York City

Teaching

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2014 (SS)

Seminar (Master): Semantic Multimedia (Blog)
Seminar (Master): Principles of Linked Data Publishing (Blog)

2013/14 (WS)

Lecture (Master): Semantic Web Technologien (Blog)

2013 (SS)

Seminar (Master): Semantic Multimedia (Blog)
Seminar (Bachelor): Multimedia Analyse Technologien (Blog)
Schülerkolleg (für Schüler der 8. bis 10. Klasse): Internetsuche und Google PageRank - Wie wird was durch wen gefunden?
- Woche 1 - 09.04.2013: Die Geschichte der Web-Suchmaschinen (pdf)
- Woche 2 - 23.04.2013: Term- und Dokumentenranking (pdf)
- Woche 3 - 07.05.2013: Google Page Rank (pdf)
- Woche 4 - 21.05.2013: Personalisierung und Web Crawling (pdf)
- Woche 5 - 04.06.2013: Semantische Suche

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Supervised Master Theses

Gerald Töpper: Erweiterung der DBpedia Ontologie und des Extraction Frameworks zur Sicherung der Datenqualität. (finished April 2012)
Peter Retzlaff: Visualisierung von Bag-of-Visual-Words-Vektoren für die Visual Concept Detection (finished March 2014)
Sebastian Stange: Evaluierung einer semantischen Videosuche und Ermittlung geeigneter Videoanalysetechniken (finished March 2014)
Michael Wolowyk: Semantic Recommender Systems (preliminary title) (in progress)

Open Master Theses

Please find a list of possible topics for Master Theses. Contact us, if you are interested in one of these topics or have own suggestions.

Video Analysis:
- OCR Spellcorrection
- Tag Relevance Estimation in Photo Communities
- Learning Local Image Descriptors
Linked Data and Semantic Web:
- Named Entity Evolution
- Authority File Mapping
- A Mereology for Media Fragments