• Journal of KIISE:Software and Applications
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• v.28 no.5
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• pp.422-430
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• 2001

웹 에이전트는 사용자가 웹을 브라우징하는 행위를 모니터하여 사용자의 관심 정보를 학습하고 사용자가 필요로 하는 웹 상의 정보를 자동 제공하는 지능형 시스템이다. 웹 에이전트가 사용자의 선호도를 학습하기 위해서는 귀납적 기계학습을 수행하는데, 이때 학습의 효율을 높이기 위해서는 사용자가 관심있어하는 문서들을 유사한 문서들로 클러스터링하여 학습 시스템에 제공하여야 한다. 본 논문에서는 웹 에이전트의 학습 시스템에 입력되는 학습대상 문서들을 보다 정확하고 효율적으로 클러스터링하여 제공하기 위해서 Top-down 방식과 Bottom-up 방식을 통합 적용한 통합방식 문서 클러스터링과 초기 클러스터 생성을 위한 평가함수를 제시한다. Top-down 방식으로는 개념적 클러스터링 알고리즘인 COBWEB을 적용하고, Bottom-up 방식으로는 교차기반(Intersection-based) 클러스터링 방식인 Etzioni의 클러스터링 알고리즘을 적용하였다.

• Annual Conference of KIPS
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• 2010.04a
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• pp.135-138
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• 2010

무선 센서 네트워크 (WSN)를 구성하는 노드들은 그 크기가 매우 작고 보유 에너지 량이 한정되어 있는 등의 제약적인 환경 때문에 에너지 효율 및 보안적인 면에서 취약하다. EECCH (Energy-Efficient Clustering scheme with Concentric Hierarchy)는 WSN에서 동심원 기반의 계층화를 통해 에너지 효율을 높인 중앙 처리 방식의 클러스터링 기법이다. WSN에서 보안 위협에 대처하기 위해 키 분배 문제를 해결해야 한다. EECCH의 계층적인 환경에서 안전한 보안 기능을 제공하기 위해 여러 기법이 복합적으로 사용되어야 한다. 본 논문에서는 사전 키 분배 기법, 단일 해쉬 함수 등의 기법을 적용하여 기밀성, 무결성, 적시성 등의 보안 요구 사항을 제공하는 향상된 EECCH 기법을 제안한다.

• Annual Conference of KIPS
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• 2008.11a
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• pp.215-218
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• 2008

최근 개인의 업무 능률 향상을 위해 일정 관리를 대행해주는 지능형 에이전트에 대한 연구가 진행중이다. 사용자는 쉽고 친숙한 인터페이스 환경을 제공하며 유연하고 풍부한 의사전달 과정인 대화를 보다 선호하게 되는데, 본 논문에서는 CAML를 사용하여 효율적인 대화 스크립트 설계 방법을 제안한다. 스크립트 설계 시, 예외처리에 시간이 많이 소요 되는 등 기존 연구에서의 문제점을 해결하기 위해 스크립트는 도메인 분석, 대화흐름 설계, 대화로그 수집 및 대화 스크립트 생성, 외부 함수 정의, 실제 일정관리에이전트에서의 적용의 단계를 거쳐 생성되며, 생성된 스크립트는 실제 대화 에이전트를 통해 일정관리의 기능을 수행한다. 10명의 사용자를 대상으로 비교 평가를 통해 제안하는 스크립트 설계방법이 우수함을 보였고, 사람 간 대화와의 유사성 역시 높음을 보였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3C
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• pp.286-292
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• 2006

Both composition and XOR are operations widely used to enhance security of cryptographic schemes. The more number of random permutations we compose (resp. XOR), the more secure random permutation (resp. random function) we get. Combining the two methods, we consider a generalized form of random function: $SUM^s - CMP^c = ({\pi}_{sc} ... {\pi}_{(s-1)c+1}){\oplus}...{\oplus}({\pi}_c...{\pi}_1)$ where ${\pi}_1...{\pi}_{sc}$ are random permutations. Given a fixed number of random permutations, there seems to be a trade-off between composition and XOR for security of $SUM^s - CMP^c$. We analyze this trade-off based on some upper bound of insecurity of $SUM^s - CMP^c$, and investigate what the optimal number of each operation is, in order to lower the upper bound.

• Journal of Korea Port Economic Association
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• v.25 no.3
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• pp.251-268
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• 2009

This study analyzes price competition between two ports theoretically using a game model. We considered two cases: in Case I, consignors are located in a given position, and in Case II, consignors are distributed uniformally between two ports. The results are as follows. In Case I, the higher consignors' preferences for quality are, the more two ports' prices increase. As the locations of consignors are closer to Port H, the price of Port H increases and that of the low quality port(Port L) decreases. In addition, when transportation cost increases, the price of Port L decreases and the price of Port H tends to increase. If the quality of Port H improves, the price of the port H increases but the price of Port L is not clearly determined. In Case II, the higher consignors' preferences for quality are, the more two ports' prices increase. As transportation cost increases, the prices of both ports decrease but the price of Port L decreases twice as fast as that of Port H. In addition, if the quality of Port H improves, the price of Port H increases but the price of Port L decreases when transportation cost is high.

• Journal of Korean Society of Transportation
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• v.26 no.1
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• pp.145-153
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• 2008

Existing shortest-path algorithms mainly consider a single attribute. But traveler actually chooses a route considering not single attribute but various attributes which are synthesized travel time, route length, personal preference, etc. Therefore, to search the optimal path, these attributes are considered synthetically. In this study route searching algorithm which selects the maximum utility route using discrete choice model has developed in order to consider various attributes. Six elements which affect route choice are chosen for the route choice model and parameters of the models are estimated using survey data. A multinomial logit models are developed to design the function of route choice model. As a result, the model which has route length, delay time, the number of turning as parameter is selected based on the significance test. We use existing shortest path algorithm, which can reflect urban transportation network such as u-turn or p-turn, and apply it to the real network.

• Journal of Technology Innovation
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• v.23 no.3
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• pp.43-65
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• 2015

Technology standard continues to exist as an social agreement throughout all industry. With development of Information and Communication, it is recently considered as a strategic factor for enhancing interoperability and increasing market dominance. Hence, technology standard research(standardization research) have a significance in analyzing the process of standard adoption and its economic effect and deriving theoretical and policy implications. However, as existing relative researches are lack in consideration on indigenous value of technology and its interoperability, there exists limitation in drawing the result of technology centered analysis. The goal of this study is to suggest new technology centered standard method by implying function of technology differentiation rate and technology preference that are deduced by technology network analysis into two stage game theory. As an example of empirical case, we selected wireless pan technology of Internet of Things, and derive its technological structure and implications related to standard.

• Journal of the Korea Society for Simulation
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• v.17 no.3
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• pp.1-8
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• 2008

It is essential to maintain constant QoS despite of cell overload or erroneous wireless link during transmission because QoS of a multimedia service may be severely degraded by small delay or packet loss. This paper deals with a cell selection method for supporting the QoS of multimedia services over heterogeneous networks. The proposed scheme is based on Fuzzy Multi-Criteria Decision Making (FMCDM), in which uncertain parameters such as user system preference, the communication cost and cell load, and the transmission delay are used in the decision process using the aggregation function in fuzzy set theory. In this scheme, errors in the evaluation parameters impose milder changes on the total evaluation value than in binary logics. Simulation is focused on the average delay and packet loss rate, and the simulation results show that our proposed method provides mobile terminals the optimal performance.

• Journal of the HCI Society of Korea
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• v.5 no.2
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• pp.25-31
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• 2010

This paper proposes a hybrid tour path planning system for multiple visitors in a museum. The proposed path planning system merges individual user profiles into a group profile by exploiting the multiplicative utilization algorithm. It then generates a tour path for the users based on mixed initiative decision of the system and the involved visitors. It automatically selects visiting sites when group users have highly similar preferences while it asks users to select their appropriate visiting sites among available sites when their preferences are different. We developed the hybrid path planning system based on a tabletop display and evaluated it with four different exhibition settings and 11 participants. We found that the mixed decision of the system and users was useful in building a tour path for a group of visitors.

• Journal of Navigation and Port Research
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• v.35 no.8
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• pp.657-665
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• 2011

This study deals with an integrated problem for deciding sequencing and storage location of export containers together at its receiving operation in the container terminal with a perpendicular layout. The preferred storage location of an export container varies with the priority of the corresponding loading operation and the waiting time of an external truck depends on its storage time. This paper proposes the mixed integer programming model considering the expected arrival time and expected finish time of an external truck and the preferred storage location for its loading operation. And we suggest the heuristic algorithm based on a simulated annealing algorithm for real world adaption. We compare the heuristic algorithm with the optimum model in terms of the computation times and total cost and the performance of the heuristic algorithm is analyzed through a numerical experiment.