• 한국시뮬레이션학회논문지
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• 제20권1호
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• pp.107-116
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• 2011

최근 가정 또는 사무실과 같은 실내 환경에서 음영지역을 해소하고 고품질의 서비스 제공을 위한 방안으로 초소형 기지국인 펨토셀(Femtocell)이 많은 관심을 받고 있다. 펨토셀은 사업자 및 사용자에게 다양한 이점을 제공하지만 펨토셀의 도입을 위해 서는 채널 선택에 따른 간섭제어, 네트워크 동기화, 자기 최적화 등 다양한 기술적 문제점이 해결되어야 한다. 이를 위해 본 연구에서는 펨토셀의 도입으로 인하여 발생 가능한 다양한 신호간섭 문제들에 대한 분석을 용이하게 하기 위한 LTE(Long Term Evolution) 시스템 기반 펨토셀 시뮬레이터를 개발하였다. 개발된 시뮬레이터는 단말 이동성, 스케줄러, 호 수락 제어, 트래픽 생성, MCS(Modulation and Coding Scheme) 결정의 5개의 블록과 이를 연결하고 관리하는 메인 모듈로 구성되어 있다. 또한 사용자의 편의성을 도모하기 위하여 시뮬레이션 결과를 실시간으로 관측할 수 있는 GUI(Graphical User Interface)를 적용하였다. 본 시뮬레이터는 실제와 유사한 환경에서 매크로셀과 펨토셀 사이의 간섭영향을 면밀히 분석하고 이동통신 시스템의 성능을 효과적으로 평가할 수 있도록 지원하며, 다양한 펨토셀 시스템을 개발하는데 크게 기여할 수 있을 것으로 예상된다.

• 전기학회논문지
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• 제58권1호
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• pp.63-68
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• 2009

As the complexity of the power system becomes higher, tests of the new devices, such as exciter and PCS(Power Conversion System) of the distributed generation sources, in the real operating condition are more important. However tests of the unverified devices in the real power system may cause hazardous malfunction of the system. In order to avoid this problem, power devices may be tested with the real-time simulators instead of the real power system. This paper presents an real-time multi machine power system simulator using PCs(Personal Computer) and Fast Ethernet. Developed real-time simulator performs the electro-mechanical dynamic simulation of multi-machine power system by the network distributed computing technique. Because the simulator consists of usual PCs and Fast Ethernet, it is possible to make up a simulation system very cheaper than the conventional real-time simulator which consists of dedicated expensive hardware devices. The performance of the developed simulator is tested and verified with the scaled model excitation system. The test which adjust the control parameters of the exciter is performed with the well-known New England 10 generator 39 bus sample power system.

• 한국컴퓨터산업학회논문지
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• 제2권12호
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• pp.1505-1516
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• 2001

The goal of Medical multimedia server is to develop computer hardware and software which would enable electronic access, storage, transmission, and display of patient data and images. Since the current network only provides so called "best-effort" services, it is impossible to satisfy QoS guarantee that is required for real time application services for emergency room, operating room etc. Accordingly, world-wide research is being made for a variety of services to provide QoS. he goal of DiffServ is to offer scalable differentiated service in Internet which are made possible by traffic classification and conditioning only performed at an edge(or a boundary) node. In case DiffServ was deployed in the Medical multimedia network, it is difficult to estimate how the QoS mechanism would affect totally the network performance. Therefore, we need to verify by simulation the design of algorithm which provide a variety of differentiated services. In QoS for Medical multimedia network, a simulator is designed and implemented using OPNET to investigate the performance of DiffServ QoS support mechanism. The developed DiffServ simulator may generate packets according to random, and bursty traffic models in order to incorporate diverse traffic conditions in the Medical multimedia network environment. Based on our simulation results, we confirmed that service differentiation is possible by using the EF(Expedited Forwarding) class in DiffServ networks.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.370-375
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• 2006

This paper suggests the method for estimating a partial discharge (PD) location using divide of the inside transformer as a grid. The PD location is found swiftly and economically compared with the typical method detecting a PD. The reason is that the location of PD is detected in the section. The estimation of PD location is trained using the Neural Network. JavaNNS(Java Neural Network Simulator) and SNNS(Stuttgart Neural Network Simulator) are used for searching the location of PD. The simulation procedure is following, The transformer is assumed that the case is a regular hexahedron. The sensor is installed in a proper location. A section of PD location is set as a target, and training set is studied with several PD locations in the inside of the transformer. As a result of training process, the learning capability of neural network is excellent. The PD location is detected by division of internal structure of transformer and application of neural network.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2112-2115
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• 2003

In this paper, we describe a SSAS (stepping stones attack simulator) that is automatic tool for testing and evaluation in TCP connection traceback system. The SSAS can pass multiple hosts that are included with hacker, middle-path hosts and victim’s system. And SSAS can also attack through commands to exploit the victim’s system. Usually, hackers do not expose their real attack positions through compromising the middle-path hosts like stepping-stones. Namely, hackers perform the stepping stones attacks in Internet. The SSAS can be utilized by developments and tests of the various countermeasure techniques of hacking. Specially, in this paper, it is used to test the performance of TCP connection traceback system.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.25-28
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• 2000

As Internet users and network traffics are explosively increased, many researches have been done to provide fast and guaranteed Internet services. The results of these efforts are Multiprotocol Lab el Switching(MPLS) and differentiated service(Diff serv) emerging as a next generation backbone net work. In this paper, we make a research on gearing (or interworking) two technology needed to support end-to-end QoS and explain sequential procedure. And we simulate the L-LSP/E-LSP proposed by Working Group of IETF to be deployed to the DiffServ module which is implemented based on the MPLS network simulator and analyze the performance of the simulation result.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.505-507
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• 2005

In this paper, a timing analysis is performed for the CAN-based simulator system for a fuel cell hybrid electric vehicles. The CAN protocol is recently being used for conventional vehicles, however, the network-induced delay can make the in-vehicle network system unstable. This problem may be occurred in the future vehicles because more ECUs are being required than recent vehicles. In order to develop a stable network-based control system, timing analysis is required at the design process. Throughout this analysis, timing parameters that affect transmission delay are examined and an effective method of predicting a sampling time for a stable communication via CAN protocol. In order to show the validityof suggested timing analysis. some experiments are performed using DSPs with CAN module.

• Journal of Communications and Networks
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• 제5권3호
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• pp.202-214
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• 2003

The central challenge in the design of ad-hoc networks is the development of dynamic routing protocol that efficiently finds route between mobile nodes. Several routing protocols such as DSR, AODV and DSDV have been proposed in the literature to facilitate communication in such dynamically changing network topology. In this paper, a Node Transition Probability (NTP) based routing algorithm, which determines stable routes using the received power from all other neighboring nodes is proposed. NTP based routing algorithm is designed and implemented using Global Mobile Simulator (GloMoSim), a scalable network simulator. The performance of this routing algorithm is studied for various mobility models and throughput, control overhead, average end-to-end delay, and percentage of packet dropped are compared with the existing routing protocols. This algorithm shows acceptable performance under all mobility conditions. The results show that this algorithm maximizes the bandwidth utilization during heavy traffic with lesser overhead.

• 한국항해항만학회지
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• 제38권4호
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• pp.385-390
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• 2014

시뮬레이터는 다양한 형태와 기능을 갖춘 여러 장치들로 구성되어 있으며, 이 장치들이 네트워크로 연동된 복잡한 구조를 이루고 있다. 이러한 이유로 시뮬레이터 개발 및 유지보수 과정에 많은 시간과 비용이 소요된다. 시뮬레이터의 성공적인 개발을 위해서는 관련 전문가들이 협력하고 업무를 분담하여 병렬적으로 수행하는 것이 이상적이지만 업무의 상호 의존성이 이를 어렵게 한다. 본 논문에서는 시뮬레이터 개발 업무를 알고리즘 구현과 이를 제외한 시스템 구현으로 나누어 두 업무의 상호 의존성을 낮추고 전문가를 지원하는 방안을 검토하였다. 특히 알고리즘 구현을 담당하는 도메인 전문가의 요구 사항을 분석함으로써 시뮬레이터 개발 지원 도구를 설계하고, 이를 활용한 시뮬레이터 개발 절차를 제안하였다. 또한 도메인 전문가의 알고리즘 개발 지원과 유연한 데이터 관리를 위해 데이터셋 개념을 도입하였고, 시뮬레이터 장비들이 유연하게 재구성될 수 있도록 네트워크 구조를 설계 하였다. 시뮬레이터 개발 지원 도구를 통해서 도메인 전문가는 알고리즘 개발에 전념할 수 있고, 효율적인 협업이 가능할 것으로 기대된다. 또한 개발 절차가 체계화 되고 더 명확해지기 때문에 개발 계획 및 관리가 용이해질 것으로 예상 된다.

• 인터넷정보학회논문지
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• 제15권3호
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• pp.53-62
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• 2014

DTN(Delay/Disruption Tolerant Network)은 행성과 행성 간의 통신, 행성과 인공위성과의 통신과 같이 종단 간 연결이 보장되지 않고, 빈번한 연결 부재가 발생하고 기존 인터넷 인프라가 충분히 갖춰지지 않는 네트워크에 적합한 차세대 네트워크이다. 본 논문에서는 DTN 환경에서의 노드 간에 접촉한 기록 데이터를 이용하여 주기적으로 만나는 것을 확인하고, 향후 만나는 시간을 예측하여, 예측한 시간을 토대로 메시지를 누구에게 보내야 효율적인지를 선별하여, 메시지를 보내도록 한다. 또한 기존 라우팅 기법인 Spray and Wait 라우팅을 선별된 노드에게 적용하는 Hybrid Spray and Wait 알고리즘을 제안한다. 제안 알고리즘을 검증하기 위해 헬싱키 대학의 ONE(Opportunistic Network Environment) Simulator를 이용하여 이를 실험하였다. 제안하는 알고리즘의 전달성공률을 Binary Spray and Wait 라우팅의 성능과 비교하였고, 10% 적은 오버헤드를 보임을 확인하였다. 또한 불필요한 메시지의 복사를 줄일 수 있음을 확인하였다.