• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.110-114
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• 2010

We describe a new method for text categorization using TextRank algorithm. Text categorization is a problem that over one pre-defined categories are assigned to a text document. TextRank algorithm is a graph-based ranking algorithm. If we consider that each word is a vertex, and co-occurrence of two adjacent words is a edge, we can get a graph from a document. After that, we find important words using TextRank algorithm from the graph and make feature which are pairs of words which are each important word and a word adjacent to the important word. We use classifiers: SVM, Na$\ddot{i}$ve Bayesian classifier, Maximum Entropy Model, and k-NN classifier. We use non-cross-posted version of 20 Newsgroups data set. In consequence, we had an improved performance in whole classifiers, and the result tells that is a possibility of TextRank algorithm in text categorization.

• The Journal of the Korea Contents Association
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• v.9 no.6
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• pp.436-443
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• 2009

There have been rapid increases to the demands for modeling diverse and complex spatial phenomena and utilizing spatial data through the computer across all the aspects of society. As a result, the importance and utilization of remote sensing and GIS's(geographic information systems) have also increased. It can produce digital data of enormous accuracy and value by incorporating remote sensing images into GIS analysis technology and make various thematic maps by classifying and analyzing land cover. Once such a map is made for the target area, it can easily do modeling and constant monitoring based on the map, revise the database with ease, and thus efficiently update geo-spatial information. Under the goal of analyzing changes to land cover along the road by combining the remote sensing and GIS technology, this study classified land cover from the images of two periods, detected changes to the six classes over ten years, and obtained statistics about the study area's quantitative area changes in order to provide basic decision making data for urban planning and development. By analyzing land use along the road, one can set up plans for the area along the road and the downtown to supplement each other.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.12
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• pp.2343-2348
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• 2008

Ant algorithm is new meta heuristic for hard combinatorial optimization problem. It is a population based approach that uses exploitation of positive feedback as well as greedy search. It was first proposed for tackling the well known Traveling Salesman Problem. In this paper, we propose the improved $AS_{rank}$ algorithms. The original $AS_{rank}$ algorithm accomplishes a pheromone updating about only the paths which will be composed of the optimal path is higher, but, the paths which will be composed the optimal path is lower does not considered. In this paper, The proposed method evaporate the pheromone of the paths which will be composed of the optimal path is lowest(worst tour path), it is reducing the probability of the edges selection during next search cycle. Simulation results of proposed method show lower average search time and average iteration than original ACS.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.189-189
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• 2019

도시화에 따른 토지이용패턴의 변화로 불투수면적이 증가하여 빗물의 침투량이 감소하고, 유출량은 증가하는 등 집중호우시 침수피해를 야기하게 된다. 또한 오염원의 증가로 수질오염과 지하수고갈에 따른 건천화 등 부정적 효과를 초래하는 것으로 알려져 있다. 최근 기후변화에 따라 물순환 체계가 변화하고 있으며, 이로 인해 도시의 홍수 및 가뭄이 극심해지고 시민의 삶의 질도 위협받고 있다. 우리나라의 경우 지속적으로 도시화 및 불투수면적이 증가하고 있으며, 집중호우의 발생빈도 또한 높아 심각한 수자원 물재와 홍수피해위험이 높다. 이에 도시의 물환경 변화 및 왜곡된 물순환 체계를 지속가능하도록 개선해야 할 필요성이 제기되었다. 환경부 및 국토부 등 정부기관에서는 물환경지속가능성을 위하여 저영향개발 기술요소를 도입하고 적용하고 있다. 본 연구에서는 침수위험지역의 저영향개발기법을 도입하여 유출저감 효과를 모의하고, 경제성 분석을 하였다. 본 연구의 대상지역은 경상남도 김해시 안동지구이며, 면적 364.2ha, 투수층면적 160.7ha, 불투수층면적 203.5ha로 불투수율은 55.90%로 산정되었다. 대상지역인 안동지구 우수관로현황 조사결과 (30년빈도 강우강도 적용) 관로의 통수능 검토시 전체관로 26.97km 중 통수능 부족관로는 15.60km로 전체대비 약 57.8%로 나타났다. 안동지구 내 우수관거는 간선관로의 경우 10년빈도, 지선관로의 경우 5년빈도로 설계, 시공되어 있으므로 각종 공단이 입지한 시가지인 안동지구는 도로포장등으로 인해 불투수층이 대부분을 차지해, 강우시 도로표면 유출수의 증대로 침수피해가 가중되는 것으로 판단되었다. 이에 저영향개발기법을 적용하여 맨홀로 유입되는 직접유출(DCIA, Directly Connected Impervious Area)를 줄이고, 유지관리 등을 고려하여 경제성을 평가하여 향후 침수위험지구 관거개량시 저영향개발기법을 활용할 수 있도록 하고자 한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.202-202
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• 2019

상수관망 시스템의 목적은 수요자에게 양적으로 안정하고 질적으로 안전한 용수를 적정 수압으로 공급하는 것이다. 그러나, 상수관망 시스템은 노후화, 시공 중 파손 등 다양한 내 외적 요인들에 의해 파괴가 불가피하며, 이를 복구하는 과정에서 단수는 필연적으로 발생하게 된다. 단수피해를 효율적으로 감소시키는 방법은 인근 배수블록과의 비상연계를 실시하는 것이다. 비상연계란, 관망의 파손 등 비정상상황 발생 시 단수구역에 용수를 공급하기 위해, 인접한 배수블록과 연결된 비상관로를 운용하여 인접 배수블록으로부터 단수구역에 용수를 공급하는 것을 의미한다. 본 연구에서는 비상연계 시 연계공급을 실시하는 배수블록에서의 문제점이 아닌 연계공급을 받는 배수블록에서의 문제점을 실제 A시 관망을 바탕으로 분석하고, 이에 대한 해결책을 제안하였다. 실제 A시에서는 직경 600mm 간선관로(수지식)의 파손으로 2지 배수블록 하단부가 단수되는 사고가 발생하였다. 이에 단수피해를 최소화하고자 인근 배수블록인 1지 배수블록과의 비상연계를 실시하였으나, 2지 배수블록 하단부의 말단부분에서 고압이 발생하고 관로 파손과 같은 추가적인 문제가 발생하였다. 본 연구에서는 A시에서 실시한 비상연계 시나리오를 구축한 후 수원에서의 유한함을 고려할 수 있는 A-PDA 기반 수리해석을 실시하여 대한 고압발생의 원인을 분석하였다. 고압 문제의 원인은 연계 공급을 실시하는 1지 배수블록과 2지 배수블록간의 고도차에 의해 발생한 것으로 사료되며, 이에 대한 해결책으로 감압밸브 추가 설치, 주요 관로 복수화 방안을 제시하였다. 이후 각 해결책에 따른 모델을 구축한 후 수리해석을 실시하여 해결책이 상수관망에 미치는 영향을 분석하였다. 본 연구는 실제 관망에서 비상연계 시 발생한 문제를 분석함으로써 비상연계 시스템 구축 시 추가적으로 발생 가능한 문제 및 해결방안을 제안하였다.

• Journal of Korea Port Economic Association
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• v.22 no.3
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• pp.79-96
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• 2006

In this paper, using the gravity model, I examined that the port traffic in the port of Pusan have been influenced by GDP of South Korea, GDP of trading countries, an agreement on maritime transport, maritime transport charge and the local economic integration, etc. In view of the policy implication based on the result of analysis by the gravity model, the port traffic and the transshipment in the port of Pusan is positively influenced by GDP of South Korea, GDP of trading countries and countries on the way of main sea route(LINE). But it is negatively influenced by maritime transport charge. Especially, when a maritime transport charge goes up 1 percentage point, it is estimated that a transshipment decreases about 0.586-0.895 percentage point. So, a maritime transport charge was found to have more effect on a transshipment than a port traffic(except transshipment).

• Journal of Korea Port Economic Association
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• v.32 no.1
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• pp.59-77
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• 2016

This paper reviews the current local logistics policy of the Incheon Metropolitan City and prioritizes policy agenda based on fuzzy AHP and IPA (Importance Performance Analysis). The analysis recommends that the city needs to keep up the current good works at the policy agenda such as early expansion of the international logistics hub and improvement of the provincial highway network.The policy agenda including the logistics parks, the transport networks and the hinterland activities are evaluated as overkilled agenda. Revitalization of the logistics database, establishment of an integrated business support center, modal shift, and public logistics support were classified as low-priority policy agenda. The policy agenda of urgent concentration includes development of new logistics business and air cargo industry.

• Journal of the Korea Society of Computer and Information
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• v.18 no.12
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• pp.75-82
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• 2013

This paper proposes a $O(n^2)$ polynomial time algorithm to obtain optimal solution for Traveling Salesman problem that is a NP-complete because polynomial time algorithm has been not known yet. The biggest problem in a large-scale Traveling Salesman problem is the fact that the amount of data to be processed is $n{\times}n$, and thus as n increases, the data increases by multifold. Therefore, this paper proposes a methodology by which the data amount is first reduced to approximately n/2. Then, it seeks a bi-directional route at a random point. The proposed algorithm has proved to be successful in obtaining the optimal solutions with $O(n^2)$ time complexity when applied to TSP-1 with 26 European cities and TSP-2 with 46 cities of the USA. It could therefore be applied as a generalized algorithm for TSP.

• Journal of the Korea Society of Computer and Information
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• v.25 no.4
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• pp.123-131
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• 2020

The pattern query in graph database has advantages of easy query expression and high query processing performance compared to relational database SQL. However, unlike the relational database, the graph database may not utilize the advantages of pattern query depending on modeling because the methodology for building the logical data model is not defined. In this study, in the is-a node modeling method that appears during the graph modeling process, we experiment that there is a difference in performance between graph pattern query when designing with a generalization model and designing with a specialization model. As a result of the experiment, it was shown that better performance can be obtained when the is-a node is designed as a specialization model. In addition, when writing a pattern query, we show that if a variable is bound to a node or edge, performance may be better than that of the variable of not bounded. The experimental results can be presented as an is-a node modeling method for pattern query and a graph query writing method in the graph database.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.84-94
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• 2021

Graph databases have been developed to efficiently store and query graph data composed of vertices and edges to express relationships between objects. Since the query types of graph database show very different characteristics from traditional NoSQL databases, benchmarking tools suitable for graph databases to verify the performance of the graph database are needed. In this paper, we propose an efficient graph database benchmarking system that supports diversity in graph inputs and queries. The proposed system utilizes OrientDB to conduct benchmarking for graph databases. In order to support the diversity of input graphs and query graphs, we use LDBC that is an existing graph data generation tool. We demonstrate the feasibility and effectiveness of the proposed scheme through analysis of benchmarking results. As a result of performance evaluation, it has been shown that the proposed system can generate customizable synthetic graph data, and benchmarking can be performed based on the generated graph data.