• Journal of the Korea Society for Simulation
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• v.19 no.3
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• pp.91-98
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• 2010

This paper is on the research result for analyzing the performance of GLORY(GLobal Resource management sYstem) used for Web Server Cluster system, which was developed at ETRI(Electronic and Telecommunication Research Institute). The paper includes the definition of Web Server Cluster System, the characteristics of the system, user oriented system performance, current performance enhancement methods, computer simulation model for GLORY and its experimental results for the performance of GLORY. GLORY is composed of 2048~1,000,000 units of PCs, and is used for Internet servers. From the results of the simulation experiments, we notice that GLORY has enough capacity to fully serve the appropriate level of Internet services. Also, the results show that Web server service time is longer than that for network transmission time but requires more DNS than expected, and that 100Mbps LAN is good enough for directly connecting Internet to the Web servers while not affecting the total system performance.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.87-91
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• 2006

With the growth of the internet, the number of wireless internet users has increased continuously up to date. However, mobile communications could not support high speed transmission rate with cheap communication fee and wireless LAN has problems in providing terminal mobility and wide area connectivity, respectively. So the WMAN standard has been newly designed to make up for these limits. The initial 802.16 specification effectively offers a solution for providing fixed users with high speed wireless communication but it does not offer terminal mobility. So the 802.16d and 802.16e have been developed as the next generation solution that can support various PHY layer (SC, SCa, OFDM, OFDMA) and offer the terminal mobility. In this paper, we propose an effective uplink scheduling algorithm for VoIP with using UGS, and we show that our proposed algorithm is superior in view of average delay and management of uplink bandwidth to conventional rtPS algorithm and the scheme in reference, with using NS-2 network simulator.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.3
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• pp.620-628
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• 2017

In this paper, we suggest a route plan sharing service for the navigation assistance service which is the second item of 16 items in maritime service portfolios (MSPs) for safety navigation based on interview process. Also, we developed scenarios for effectiveness evaluation of the proposed service, and conducted simulations using full mission ship handling simulator (FMSS) for effectiveness evaluation of proposed services based on the developed scenarios. Through the simulations, we analyzed proximity measures, controllability statistics and subjective evaluations to assess the usefulness of suggested service. If accomplishing the test for new services to apply real ships and vessel traffic (VTS) center, there has possibilities to occur various risks in terms of time/cost problems. Therefore, there is needs for the preliminary effectiveness evaluation processes necessarily when adopts and implements new services. Because we expected the service that is helpful for safety navigation, but the test results are not when conducted a simulation.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.8
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• pp.915-920
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• 2015

Recently, many companies try to offer various services using drones. Especially, the drone delivery system is a good example. However, the drone delivery service has some problems since the heavy parcels flies over the people walking down streets, so many things must be considered such as dropping mails by collision of drones. To resolve the problem, in this paper, a inter-drone network communication will be used to design the topology and to simulate in the Opnet simulator for the performance evaluation. Additionally, the topology with random mobility of trajectory of drones is also designed and simulated for the result.

• Proceedings of the Korean System Dynamics Society
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• 2003.02a
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• pp.29-55
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• 2003

최근의 통신서비스 시장은 경쟁의 도입과 기술의 발전이라는 두 축에 힘입어 양질의 서비스를 보다 저렴한 요금으로 소비자들에게 제공하고자 노력하여 왔다. 그러나 이러한 통신서비스의 질적 향상 노력에도 불구하고 여전히 통신서비스의 품질은 소비자들의 기대수준에는 미치지 못하고 있다는 지적이 있다 더욱이 문제가 되는 것은 소비자가 인지하고 있는 통신 서비스 품질의 기대수준은 시간의 흐름에 따라 동태적으로 변화하는 것이어서 한 시점에서의 통신 서비스 품질 수준의 측정으로는 정책적으로 큰 의미를 설명하기 어려운 실정이다. 이와 관련하여 많은 선행 연구들이 다양한 측면에서 시행되어져 왔지만 이제까지의 많은 선행 연구들은 대부분이 통신서비스의 특성을 제대로 고려하지 않고, 고객만족의 향상과 불일치를 가져오고 있는 성능품질만을 측정한다거나, 시간의 흐름에 따라 변화해 가는 소비자가 서비스에 대해 인지하고 있는 중요도나 기대수준을 고려하지 않고 있으며, 각 구성요소간의 동태적 인과고리에 대한 고려 없이 연구가 이루어져 전반적인 통신 서비스의 고객만족을 전체적인 시각에서 평가한 연구는 극히 드물다. 따라서 본 연구는 통신서비스의 고객만족을 피드백 관점, 동태적 관점, 사실적 관점의 시스템 다이내믹스 방법론을 적용하여 전반적인 동태적 고객만족 모형을 구현하고 이를 정책적으로 활용할 수 있는가에 대한 접근을 시도하였다. 고객만족은 결코 한순간에 머물러 있는 것이 아니며 체감품질 및 기대수준의 영향을 받아 지속적으로 변화해간다 따라서 어떻게 기대수준을 관리하고 고객의 기대에 부응하는 체감품질을 관리하는 것이 지속적인 고객만족을 획득할 수 있는 가를 시뮬레이션 모형을 통해 가시적으로 시스템의 행태를 구현함으로써 그 이해의 폭을 넓히고자 시도하였다.으로써 웹에서의 혁신적이며 크로스 사이트, 크로스 장르적인 컨텐츠 플래닝의 가능성을 시사하는데 의의가 있다고 하겠다.y used to some of interactive storytelling through hyper text in CD-ROM and web sites. More complicated and different structured models were born through games that offered graphics, virtual spaces and interactivity. When drawn onto a structural graph, few attributes and similarities seem to occur. This paper will try to outline and discuss structural graphs of interactive storytelling methods and suggest some ways for better storytelling design.eal sales volume, but the case study could verified that this method is effective to the evaluation of marketability in case of completely new product got on the typical category and the product category could be set up the population clearly.의 무게와 부피는 24주간 다소 감소하는 경향을 보였으나 통계적인 유의차는 없었다. 냉동저장 감자의 무게와 부피 변화는 48주간 전혀 없었다. 상온 냉장저장 감자의 조직의 강도(hardness)는 24주

• Proceedings of the Korean Information Science Society Conference
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• 2010.06b
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• pp.77-82
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• 2010

서비스 지향 아키텍처 기반의 소프트웨어 시스템은 서비스 단위의 컴포넌트 조합에 의해 기능이 수행된다. 이러한 조합된 서비스에 대한 테스팅은 주로 서비스 조합 명세서인 WS-BPEL 명세를 기반으로 기능적인 측면에 초점을 두어 수행 되었다. 최근에 서비스 지향 아키텍처가 임베디드 소프트웨어 분야에 적용되면서 서비스 조합에 대한 성능 관련 요구사항의 중요성이 부각되고 있다. 그러나 기존의 성능 테스트는 각 서비스의 응용 어플리케이션에 성능 측정을 위한 코드삽입을 필요로 함으로써 테스트 비용을 증가시킨다. 또한 시뮬레이션을 통한 성능 테스트가 이루어지기 때문에 정확한 성능을 테스트하기 어렵다. 따라서 본 논문에서는 WS-BPEL을 이용한 조합된 서비스의 효과적인 성능 테스트를 위해 WS-BPEL을 확장하는 방법을 제안한다. 제안하는 확장 기법은 관점 지향 프로그래밍의 Aspect 개념을 WS-BPEL에서 사용할 수 있도록 함으로써 WS-BPEL을 이용한 테스팅에서 조합된 서비스의 성능 테스트를 효과적으로 수행할 수 있는 기회를 제공한다. 또한 본 확장 기법은 성능 테스트뿐만 아니라 다른 비 기능적 요구사항에 대한 테스트에도 활용될 수 있다.

• Spatial Information Research
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• v.17 no.1
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• pp.25-37
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• 2009

In this paper, we propose techniques for hazard analysis of curved road based on USN. The techniques consist of models and algorithms. Models of curved road, road direction, sensor, vehicle and hazard are proposed. To analyze hazard in curved road and give warning to corresponding vehicle in realtime multi-level algorithms are proposed. An application program implements the models and algorithms to simulate proposed techniques with real-time visualization.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.466-469
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• 2011

Recently, a new theoretical and methodological approach for computational science is becoming more and more popular for analyzing and solving scientific problems in various scientific disciplines such as Computational fluid dynamics, Chemistry, Physics, Structural Dynamics, Computational Design and applied research. Computational science is a field of study concerned with constructing mathematical models and quantitative analysis techniques and using large computing resources to solve the problems which are difficult to approach in a physical experimentally. In this paper, we present R&D of EDISON open integration platform that allows anyone like professors, researchers, industrial workers, students etc to upload their advanced research result such as simulation SW to use and share based on the cyber infrastructure of supercomputer and network. EDISON platform, which consists of 3 tiers (EDISON application framework, EDISON middleware, and EDISON infra resources) provides Web portal for education and research in 5 areas (CFD, Chemistry, Physics, Structural Dynamics, Computational Design) and user service.

• Journal of the Korea Society for Simulation
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• v.24 no.3
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• pp.61-68
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• 2015

Mobile ad hoc networks (MANETs) are self-organized dynamic networks populated by mobile nodes. This paper presents the improved cross-layer approach to complement the recent works for video transmission services on MANET. We use a statistical design of experiment and analysis in order to investigate interactions between major factors of each layer effectively with minimizing ns-3 simulation run time. The proposed cross-layer approach considers MANET protocol layers (i.e., physical, network and transmission layers) and an application layer (i.e., a video encoder) as factors simultaneously. In addition, the approach defines an objective video quality metric as a response variable. The result of this paper can be applicable as a preliminary research to design an optimized video transmission application which has ability to adjust controllable factors to dynamic uncontrollable factors.

• Journal of Korea Port Economic Association
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• v.32 no.2
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• pp.137-156
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• 2016

This study analyzes the optimal service levels of exclusive container terminals in terms of the optimal berth occupancy rate and the ships' waiting ratios, based on the number of berths. We develop a simulation model using berth throughput data from pier P, Busan New Port, a representative port in Korea, and apply the simulation results to different numbers of berths. In addition to the above results, we analyze the financial data and costs of delayed ships and delayed cargoes for the past three years from the viewpoints of the terminal operation company (TOC), shipping companies, and shippers to identify the optimal service level for berth occupancy rates that generate the highest net profit. The results show that the optimal levels in the container terminal are a 63.4% berth occupancy rate and 10.6% ship waiting ratio in berth 4,66.0% and 9.6% in berth 5, and 69.0% and 8.5% in berth 6. However, the results of the 2013 study by the Ministry of Maritime Affairs and Fisheries showed significantly different optimal service levels: a 57.1% berth occupancy rate and 7.4% ship waiting ratio in berth 4; 63.4% and 6.6% in berth 5; and 66.6% and 5.6% in berth 6. This suggests that optimal service level could change depending on when the analysis is performed. In other words, factors affecting the optimal service levels include exchange rates, revenue, cost per TEU, inventory cost per TEU, and the oil price. Thus, optimal service levels can never be fixed. Therefore, the optimal service levels for container terminals need to be able to change relatively quickly, depending on factors such as fluctuations in the economy, the oil price, and exchange rates.