Research

• General Research Topics: Data Mining & Big Data Analytics, Computer & Information Security, Social Network Analysis, Recommender System & Personalization, Database
• Specific Research Topics: Analytic & Optimization Approach, Algorithmic Method, Data Analysis, Empirical Analysis

1. S.K. Dewitz, Y.U. Ryu, & R.M. Lee. "Defeasible Reasoning in Law," Decision Support Systems, Vol. 11, No. 2, pp. 133-155, 1994.
2. Y.U. Ryu & R.M. Lee. "Defeasible Deontic Reasoning and Its Applications to Normative Systems," Decision Support Systems, Vol. 14, No. 1, pp. 59-73, 1995.
3. R.M. Lee & Y.U. Ryu. "DX: A Deontic Expert System," Journal of Management Information Systems, Vol. 12, No. 1, pp. 145-169, 1995.
4. Y.U. Ryu. "Conditional Deontic Logic Augmented with Defeasible Reasoning," Data & Knowledge Engineering, Vol. 16, No. 1, pp. 73-91, 1995.
5. Y.U. Ryu. "A Hierarchical Constraint Logic Modeling of Multilateral Trade Matching in a Commodity Auction Market," Annals of Operations Research, Information Systems and Operations Research, Part I: Models of Systems (R. Ramesh and H. R. Rao, Editors), Vol. 71, pp. 317-334, 1997.
6. Y.U. Ryu. "Logic Based Representation and Reasoning about Knowledge of Constrained Resources," Knowledge-Based Systems, Vol. 10, No. 2, pp. 71-80, 1997.
7. Y.U. Ryu. "Constraint Logic Programming Framework for Integrated Decision Support," Decision Support Systems, Vol. 22, No. 2, pp. 155-170, 1998.
8. Y.U. Ryu. "Specification of Contractual Obligations in Formal Business Communication," Data & Knowledge Engineering, Vol. 26, No. 3, pp. 309-326, 1998.
9. Y.U. Ryu. "Logic-Based Modeling of Resource Consumption and Production," Decision Support Systems, Vol. 22, No. 3, pp. 243-257, 1998.
10. Y.U. Ryu & S.-C. Hong. "A Computational Model of Continuous Trading in Auction Markets: A Parallel Expert System Approach," New Review of Applied Expert Systems, Vol. 4, pp. 33-45, 1998.
11. Y.U. Ryu. "A Hierarchical Constraint Satisfaction Approach to Product Selection for Electronic Shopping Support." IEEE Transactions on Systems, Man, and Cybernetics (Part A: Systems and Humans), Vol. 29, No. 6, pp. 525-532, 1999.
12. J. Lee & Y.U. Ryu. "Exploration, Exploitation, and Adaptive Rationality: The Neo-Schumpeterian Perspective." Simulation Modelling Practice and Theory, Vol. 10, Nos. 5-7, pp. 297-320, 2002.
13. Y.U. Ryu, R. Chandrasekaran, & V. Jacob. "Prognosis Using an Isotonic Prediction Technique," Management Science, Vol. 50, No. 6, pp. 777-785, 2004.
14. I. Choi, H. Jung, M. Song, & Y.U. Ryu "IPM-EPDL: An XML-Based Executable Process Definition Language," Computers in Industry, Vol. 56, No. 1, pp. 85-104, 2005.
15. Y.U. Ryu & W.T. Yue. "Firm Bankruptcy Prediction: Experimental Comparison of Isotonic Separation and Other Classification Approaches," IEEE Transactions on Systems, Man, and Cybernetics (Part A: Systems and Humans), Vol. 35, No. 5, pp. 727-737, 2005.
16. R. Chandrasekaran, Y.U. Ryu, V. Jacob, & S. Hong. "Isotonic Separation," INFORMS Journal on Computing, Vol. 17, No. 4, pp. 462-474, 2005.
17. V. Jacob, R. Krishnan, & Y.U. Ryu. "Internet Content Filtering Using Isotonic Separation on the PICS Specification," ACM Transactions on Internet Technology, Vol. 7, No. 1, Article No. 1, 2007.
18. Y.U. Ryu, R. Chandrasekaran, & V. Jacob. "Data Classification Using the Isotonic Seeparation Technique: Application to Breast Cancer Prediction," European Journal of Operational Research, Vol. 181, No. 2, pp. 842-854, 2007.
19. W.T. Yue, M. Cakanyildirim, Y.U. Ryu & D. Liu. "Network Externalities, Layered Protection and IT Security Risk Management," Decision Support Systems, Vol. 44, No. 1, pp. 1-16, 2007.
20. Y.U. Ryu & H.-S. Rhee. "Improving Intrusion Prevention Models: Dual-Threshold and Dual-Filter Approaches," INFORMS Journal on Computing, Vol. 20, No. 3, pp. 356-367, 2008.
21. Y.U. Ryu & H.-S. Rhee. "Evaluation of Intrusion Detection Systems under an Inspection Constraint," ACM Transactions on Information and System Security, Vol. 11, No. 4, Article No. 20, 2008.
22. W.T. Yue, M. Cakanyildirim, & Y.U. Ryu. "The Management of Intrusion Detection: Configuration, Inspection, and Investment," European Journal of Operational Research, Vol. 195, No. 1, pp. 186-204, 2009.
23. M. Mannino, Y. Yang, & Y.U. Ryu. "Classification Algorithm Sensitivity to Training Data with Non Representative Attribute Noise," Decision Support Systems, Vol. 46, No. 3, pp. 743-751, 2009.
24. H.K. Kim, J.K. Kim, & Y.U. Ryu. "Personalized Recommendation over a Customer Network for Ubiquitous Shopping," IEEE Transactions on Services Computing, Vol. 2, No. 2, pp. 140-151, 2009.
25. H.-S. Rhee, C.-T. Kim, & Y.U. Ryu. "Self-Efficacy in Information Security: Its Influence on End Users' Information Security Practice Behavior," Computers & Security, Vol. 28, No. 8, pp. 816-826, 2009.
26. J. Lee, S.H. Park, Y.U. Ryu & Y.S. Baik. "A Hidden Cost of Strategic Alliances under Schumpeterian Dynamics," Research Policy, Vol. 39, No. 2, pp. 229-238, 2010.
27. J.K. Kim, H.K. Kim, H.Y. Oh, & Y.U. Ryu. "A Group Recommendation System for Online Communities," International Journal of Information Management, Vol. 30, No. 3, pp. 212-219, 2010.
28. H.K. Kim, Y.U. Ryu, Y. Cho, & J.K. Kim. "Customer-Driven Content Recommendation over a Network of Customers," IEEE Transactions on Systems, Man, and Cybernetics (Part A: Systems and Humans), Vol. 42, No. 1, pp. 48-56, 2012.
29. H.-S. Rhee, Y.U. Ryu, & C.-T. Kim. "Unrealistic Optimism on Information Security Management," Computers & Security, Vol. 31, No. 2, pp. 221-232, 2012.
30. M. Chen & Y.U. Ryu. "Facilitatin Effective User Navigation through Website Structure Improvement," IEEE Transactions on Knowledge and Data Engineering, Vol. 25, No. 3, pp. 571-588, 2013.
31. Y.U. Ryu, J.K. Kim, & I.Y. Choi. "The Role of IT in Korea's Economic Development," Information Technology and Management, Vol. 14, No. 1, pp. 3-6, 2013.
32. H.S. Moon, J.K. Kim, & Y.U. Ryu. "A Sequence-Based Filtering Method for Exhibition Booth Visit Recommendations," International Journal of Information Management, Vol. 33, No. 4, pp. 620-626, 2013.
33. M. Chen, V.S. Jacob, S. Radhakrishnan, & Y.U. Ryu. "Can Payment-Per-Click Induce Improvements in Click Fraud Identification Technologies?" Information Systems Research, Vol. 26, No. 4, pp. 754-772, 2015.
34. I.Y. Choi, M.G. Choi, J.K. Kim, & Y.U. Ryu. "Collaborative Filtering with Facial Expression for Online Video Recommendation," International Journal of Information Management, in press.

1. R.M. Lee & Y.U. Ryu. "Event Grammars: A Modeling Representation for Business Procedures," in Proceedings of the 22nd Hawaii International Conference on System Sciences, Vol. 2, pp. 553-559, 1989.
2. Y.U. Ryu. "Tuning Database Management Systems to Management Information Systems (Extended Abstract)," in Proceedings of the 2nd International Conference of the Information Resource Management Association, 1991.
3. Y.U. Ryu & R.M. Lee. "Defeasible Deontic Reasoning: A Logic Programming Model," in Proceedings of the 1st International Workshop on Deontic Logic in Computer Science, Amsterdam, The Netherlands, pp. 347-363, 1991.
4. Y.U. Ryu. "Logical Specification of Resource Consumption and Production," in Proceedings of the 29th Hawaii International Conference on System Sciences, Vol. 2, pp. 39-46, 1996.
5. Y.U. Ryu. "Relativized Deontic Modalities for Contractual Obligations in Formal Business Communication," in Proceedings of the 30th Hawaii International Conference on System Sciences, Vol. 4, pp. 485-493, 1997.
6. Y.U. Ryu. "Approximate Constraint Satisfaction over a Constraint Hierarchy: A Preliminary Study," in Proceedings of the 31st Hawaii International Conference on System Sciences, Vol. 5, pp. 134-141, 1998.
7. Y.U. Ryu. "Dynamic Construction of Product Taxonomy Hierarchies for Assisted Shopping in Electronic Marketplaces," in Proceedings of the 31st Hawaii International Conference on System Sciences, Vol. 5, pp. 196-204, 1998.
8. Y.U. Ryu & S.-C. Hong. "Negotiation Support in a Commodity Trading Market," in Proceedings of the 31st Hawaii International Conference on System Sciences, Vol. 5, pp. 233-241, 1998.
9. V. Jacob, R. Krishnan, Y.U. Ryu, R. Chandrasekaran, & S. Hong. "Filtering Objectionable Internet Content," in Proceedings of the 20th International Conference on Information Systems, pp. 274-278, 1999.
10. Y.U. Ryu, R. Chandrasekaran, & V. Jacob. "Disease Prognosis with an Isotonic Prediction Technique," in Proceedings of the 9th Workshop on Information Technologies and Systems, pp. 26-31, 1999.
11. W.T. Yue, M. Cakanyildirim, Y.U. Ryu, & D. Liu. "IT Security Risk Management under Network Effects and Layered Protection Strategy," in Proceedings of the 2nd Symposium on Intelligence and Security Informatics, 2004.
12. H.-S. Rhee, Y.U. Ryu, & C.-T. Kim. "I Am Fine but Your Are Not: Optimistic Bias and Illusion of Control on Information Security," in Proceedings of the 26th International Conference on Information Systems, 2005.
13. Y.U. Ryu & H.-S. Rhee. "Operational Models of Intrusion Prevention Systems," in Proceedings of the 15th Workshop on Information Technologies and Systems, pp. 63-68, 2005.
14. Y.U. Ryu, H.K. Kim, Y.H. Cho, & J.K. Kim. "Peer-Oriented Content Recommendation in a Social Network," in Proceedings of the 16th Workshop on Information Technology and Systems, pp. 115-120, 2006.
15. M.V. Mannino, Y. Yang, & Y.U. Ryu. "Classification Algorithm Sensitivity to Training Data with Non-Representative Attribute Noise," in Proceedings of the 13th Americas Conference on Information Systems, 2007.
16. Y.U. Ryu, H.K. Kim, J.K. Kim, & Y.H. Cho. "Experimental Evaluation of Recommendation over a Customer Network," in Proceedings of the 17th Workshop on Information Technology and Systems, pp. 158-163, 2007.
17. M. Chen & Y.U. Ryu. "Improving Web Site Structure to Facilitate Effective User Navigation," in Proceedings of the 29th International Conference on Information Systems, 2008.
18. M.V. Mannino, Y. Yang, & Y.U. Ryu. "Understanding the Relationship between Actual and Artificial Deception: Reducing the Cost of Collecting Deceptive Data," to appear in Proceedings of the 18th Workshop on Information Technologies and Systems, pp. 43-48, 2008.
19. S. Lee, Y.U. Ryu, & J.K. Kim. "IT Investment and Economic Performance: A Causality Analysis over Multiple Countries," in Proceedings of the 18th Workshop on Information Technologies and Systems, pp. 230-235, 2008.
20. J.K. Kim, M.K. Jang, H.K. Kim, & Y.U. Ryu. "A Personalized Preference Boundary-Based Procedure for Recommending New Items," in Proceedings of the 8th Workshop on eBusiness, 2009.
21. H.K. Kim, J.K. Kim, & Y.U. Ryu. "A Local Scoring Model for Recommendation," in Proceedings of the 20th Workshop on Information Technologies and Systems, 2010.
22. I.Y. Choi, H.K. Kim, Y.U. Ryu, & J.K. Kim. "A Tourism Recommender System Based on Approximate Constraint Satisfaction," in Proceedings of LC CNS/KrAIS Workshop on the Future of IS Research, 2010.
23. Y.U. Ryu, J.K. Kim, K.H. Im, & H. Hong. "Neural Network Analysis of Right-Censored Observations for Occurrence Time Prediction," in Lecture Notes in Business Information Processing (LNBIP), 2011. (Proceedings of the 10th Workshop on eBusiness)
24. M. Chen, V.S. Jacob, S. Radhakrishnan, & Y.U. Ryu. "The Effect of Fraud Investigation Cost on Pay-Per-Click Advertising," The 11th Annual Workshop on the Economics of Information Security, 2012.
25. H.S. Moon, J.K. Kim, Y.H. Kim, & Y.U. Ryu. "A Booth Recommendation Procedure Using Visit Sequences in Exhibitions," in Proceedings of International Conference on Marketing Studies (ICMS2012), 2012.
26. M.K. Jung, J.K. Kim, Y.U. Ryu, & H.C. Ahn. "An Intelligent Determination Model of Users' Emotion Using Sequential Neural Network," in Proceedings of International Conference on Marketing Studies (ICMS2012), 2012.
27. D. Kim, Y. Kwark, & Y.U. Ryu. "The Effect of Collective Efficacy and Network Dependence on Managers' Information Security Risk Perception," in Proceedings of KrAIS/LG CNS Research Workshop, 2012.
28. M. Chen, V.S. Jacob, S. Radhakrishnan, & Y.U. Ryu. "The Effect of Third Party Investigation on Pay-Per-Click Advertising," in Proceedings of the 33rd International Conference on Information Systems, 2012.
29. D.J. Kim, Y.U. Ryu, & Y. Kwark. "Information Security Collective Efficacy and Vulnerability: A Cross-Country Comparison," in Proceedings of the 34th International Conference on Information Systems, 2013.
30. Y.U. Ryu, J.K. Kim, & H.K. Kim. "A Local Scoring Model for Diversified Recommendation," in Proceedings of the 34th International Conference on Information Systems, 2013.
31. I.Y. Choi, M.G. Oh, J.K. Kim, & Y.U. Ryu. "Analysis of Facial Expression for Online Video Recommendation," in Proceedings of the 24th Workshop in Information Technologies and Systems, 2014.
32. I.Y. Choi, J.K. Kim, & Y.U. Ryu. "A Two-Tiered Recommender System for Tourism Product Recommendations," in Proceedings of the 48th Annual Hawaii International Conference on System Sciences, pp. 3354-3363, 2015.
33. Y.U. Ryu. "Firm Failure Timeline Prediction: Math Programming Approaches," in Proceedings of the 49th Annual Hawaii International Conference on System Sciences, pp. 1181-1187, 2016.
34. S. Oh, Y.U. Ryu, & H. Yang. "Supply Chain Capabilities and Information Technology Charcteristics: Interaction Effects on Firm Performance," in Proceedings of the 49th Annual Hawaii International Conference on System Sciences, pp. 1417-1425, 2016.

1. Y.U. Ryu & R.M. Lee. "Defeasible Deontic Reasoning: A Logic Programming Model," in J.-J.Ch. Meyer & R.J. Wieringa (Editors), Deontic Logic in Computer Science, John Wiley & Sons, pp. 224-241, 1993.
2. Y.U. Ryu & R.M. Lee. "Deontic Logic Viewed as Defeasible Reasoning," in D. Nute (Editor), Defeasible Deontic Logic, Synthese Library Volume 236, Kluwer, pp. 123-137, 1997.

1. I. Choi & Y.U. Ryu. Visual Logic Modeling Environment and Its Application to Network Flow Optimization Problems. Research Report CBDA-162, Center for Business Decision Analysis, The University of Texas at Austin, 1990
2. Y.U. Ryu & R.M. Lee. Defeasible Deontic Reasoning and Its Applications to Normative Systems. Technical Report TR-1992-07-01, Erasmus University Research Institute for Decision and Information Systems (EURIDIS), Erasmus University, Rotterdam, The Netherlands, 1992.
3. Y.U. Ryu & R.M. Lee. A Formal Representation of Normative Systems: A Defeasible Deontic Reasoning Approach. Research Monograph RM-1992-08-01, Erasmus University Research Institute for Decision and Information Systems (EURIDIS), Erasmus University, Rotterdam, The Netherlands, 1992.

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