• Journal of the Korean Society for information Management
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• v.21 no.1
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• pp.173-186
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• 2004

This study examines coverage and coverage overlap of the three major Korean web directories, Naver, Yahoo Korea, and Empas. This study also suggests a methodology for collecting and processing web sites provided by these web directories. A method for napping main categories was developed. Each directory provided registered web pages in a slightly different way. Reference links had a significant influence on the coverage of each web directory. The overlap of pages among three directories was quite low, It is expected that this study could contribute to the field of web research by providing insights to how directories provide web pages and suggesting a methodology for the analysis of directory coverage.

• Journal of the Korean Geographical Society
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• v.43 no.2
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• pp.220-234
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• 2008

In many security monitoring contexts, the performance or efficiency of surveillance sensors/networks based on a single sensor type may be limited by environmental conditions, like illumination change. It is well known that different modes of sensors can be complementary, compensating for failures or limitations of individual sensor types. From a location analysis and modeling perspective, a challenge is how to locate different modes of sensors to support security monitoring. A coverage-based optimization model is proposed as a way to simultaneously site k different sensor types. This model considers common coverage among different sensor types as well as overlapping coverage for individual sensor types. The developed model is used to site sensors in an urban area. Computational results show that common and overlapping coverage can be modeled simultaneously, and a rich set of solutions exists reflecting the tradeoff between common and overlapping coverage.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.437-439
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• 2021

SPL 방법론을 적용하여 개발한 제품군 시험은 모든 제품에서 사용되는 공통 부분과 일부 또는 단일 제품에서만 사용되는 가변 부분을 종합적으로 고려해야 하기 때문에 단일 소프트웨어 시험과는 상당히 다르다. 시험 커버리지는 작성된 시험에 대한 적절성을 측정하는 데에 사용되는 동시에 적절한 시험을 작성하기 위한 가이드로 사용되기 때문에 중요하다. SPL 시험에서 시험 커버리지 측정은 제품군을 구성하는 멤버제품 별로 측정될 수도 있지만, 이는 재사용을 기반으로 중복된 개발관련 활동의 최소화를 지향하는 SPL 의 원칙에 맞지 않다. 따라서 개별 제품이 아닌 SPL 수준에서 시험 커버리지 기준을 측정하고 시험의 적절성을 평가하기 위해서는 다른 방법이 필요하다. 이 논문에서는 구성가능한 소프트웨어 시스템(highly configurable software system)에 SPL 시험 방법을 적용하여 SPL 기반 제품군을 위한 시험 커버리지의 측정 방법을 제안하고 실험의 수행 결과를 기술하여 제안한 방법의 적절성을 검증한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.1
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• pp.183-189
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• 2018

This paper proposes distributed file placement and coverage expansion techniques for mitigating the traffic bottleneck in backhaul for small-cell networks. In order to minimize the backhaul load with limited memory space, the proposed scheme controls the coverage and file placement of base station according to file popularity distribution and memory space of base stations. In other words, since the cache hit ratio is low when there is small memory capacity or widespread file popularity distribution, the base stations expand its coverage and cache different set of files for the user located in overlapped area to exploit multiple cached file sets of base stations. Our simulation results show that the proposed scheme outperforms the conventional cache strategy in terms of network throughput when there is small memory capacity or widespread file popularity distribution.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.10
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• pp.365-370
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• 2014

Although Internet of Things already became a new paradigm on service on network, we should pay more effort for studying about its testing method, since humans, things and environments in IoT are connected to each other without any restrictions. Earlier researches based on emulators showed that such virtual devices on emulators had unavoidable gap between them and real things. Furthermore, growth of connection complexity between the devices and loosing of restrictions make the gap wider. Accordingly, in this paper, we suppose a method of test coverage measurement based on BitTorrent for IoT environment. It has cooperation features among homogeneous devices with avoiding the overlapping on each part of whole test process.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1A
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• pp.41-49
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• 2009

A crucial issue in deploying wireless sensor networks is to perform a sensing task in an area of interest in an energy-efficient manner since sensor nodes have limited energy Power. The most practical solution to solve this problem is to use a node wake-up scheduling protocol that some sensor nodes stay active to provide sensing service, while the others are inactive for conserving their energy In this paper, we present a simple wake-up scheduling protocol, which can maintain sensing coverage required by applications and yet increase network lifetime by turning off some redundant nodes. In order to do this, we use the concept of a weighted average distance. A node decides whether it is active or inactive based on the weighted average distance. The proposed protocol allows sensor nodes to sleep dynamically while satisfying the required sensing coverage.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.110-113
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• 2022

인터넷을 통해 주위 사물과 연결된 차량은 사용자에게 편리성을 제공하기 위해 다양한 콘텐츠를 요구하는데 클라우드로부터 가져오는 시간이 비교적 오래 걸리기 때문에 차량과 물리적으로 가까운 위치에 캐싱하는 기법들이 등장하고 있다. 본 논문에서는 기반 시설이 밀집하게 설치된 도시 환경에서 maximum distance separable(MDS) 코딩을 사용해 road side unit(RSU)에 캐싱하는 방법에 대해 연구하였다. RSU의 중복된 서비스 커버리지 지역을 고려하여 차량의 콘텐츠 요구에 대한 RSU hit ratio를 높이기 위해 deep Q-learning(DQN)를 사용하였다. 실험 결과 비교 알고리즘보다 hit raito 측면에서 더 높은 성능을 보이는 것을 증명하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.129-131
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• 2017

In the special situations such as the extension or construction of networks, network sharing can be a more favorable alternative. In this point, this research is to review the types and characteristics related to network sharing among mobile network operators(MNOs).

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.2
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• pp.7-12
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• 2010

In this paper, we analyze and simulate the performance of a cooperative communication system adopting a maximum likelihood (ML) equalizer. In wireless communication systems, cooperative communication schemes employing several relays can be applied for extending the communication coverage. It is assumed that both relays and user terminals can move. Therefore, coverages of two or more relays can overlap each other. If wanted and interfering signals are transmitted through the same channel and there are one terminal in the overlapped region, its performance is degraded due to interference. Hence, we use a ML equalizer for rejecting the effect of interfering signal and enhancing the communication system performance. The cooperative system performance is evaluated in terms of bit error probability. From the simulation results, it is demonstrated that the ML receiver shows good interference cancellation performance although its complexity is high.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.10
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• pp.708-714
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• 2014

Wireless sensor networks (WSNs) generally consist of densely deployed sensor nodes that depend on batteries for energy. Having a large number of densely deployed sensor nodes causes energy waste and high redundancy in sensor data transmissions. The problems of power limitation and high redundancy in sensing coverage can be solved by appropriate scheduling of node activity among sensor nodes. In this paper, we propose a cellular automata based node scheduling algorithm for prolonging network lifetime with a balance of energy savings among nodes while achieving high coverage quality. Based on a cellular automata framework, we propose a new mathematical model for the node scheduling algorithm. The proposed algorithm uses local interaction based on environmental state signaling for making scheduling decisions. We analyze the system behavior and derive steady states of the proposed system. Simulation results show that the proposed algorithm outperforms existing protocols by providing energy balance with significant energy savings while maintaining sensing coverage quality.