• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.688-698
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• 2015

This paper presents a modeling and a controller design for a hybrid wind turbine generator, especially with an operating mode of battery energy-storage system and a dumpload that contribute to the frequency control of the system while diesel-synchronous unit is not in operation. The proposed control scheme is based on a robust tracking controller, which takes an account of system uncertainties due to the wind flow and load variations. In order to provide robustness for system uncertainties, the range of operation is partitioned into three operating conditions as sub-models in the controller design. In the simulation study, the proposed robust tracking controller (RTC) is compared with the conventional proportional-integral (PI) controller. Simulation results show that the effectiveness of the RTC against disturbances caused by wind speed and load variation. Thus, better quality of the hybrid wind power system is achieved.

• 대한전자공학회논문지TC
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• 제49권1호
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• pp.59-67
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• 2012

본 논문은 10G G-PON(Gigabit passive optical network) 네트워크와 NGN(Next generation network) 연동 구조를 설계하고, 10G G-PON 연동 시 문제점 해결을 위한 동적 GEM(G-PON encapsulation mode) Port-ID 할당 방법을 제안했다. 동적 GEM Port-ID 할당 방법은 OMCI(ONT management control and interface) 구조 설계를 통해 IP 주소와 포트 번호를 혼합한 형태의 맵핑 구조를 갖는다. 이는 NGN이 요구하는 클래스 기반 QoS(Quality of service) 뿐만 아니라 트래픽 단위의 QoS 지원까지 가능한 구조로서, 기존 G-PON 네트워크를 NGN에 그대로 적용시킨 구조 보다 QoS 지원에 있어 30% 이상 성능을 향상 시킨다.

• 대한원격탐사학회지
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• 제36권6_2호
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• pp.1493-1507
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• 2020

KOMPSAT-3A는 2015년 3월 발사하여 약 6개월의 기간 동안 초기 검보정을 수행한 이후 지난 8년 동안 성공적으로 KOMPSAT-3A 자료를 사용자들에게 배포하였으며, 수집된 영상 자료는 지도제작, GIS, 국토관리 등의 다양한 분야에서 정성적, 정량적 정보 추출의 기초 자료로 활용되고 있다. 한국항공우주연구원에서는 KOMPSAT-3A의 영상제품군에서 추출되는 정보의 정확도 및 신뢰도를 확보하기 위해 주기적으로 영상 품질과 인공위성 하드웨어 특성을 확인하고 있다. 또한 KOMPSAT-3A의 탑재체, 자세제어 센서들의 노후화에 따른 영상 품질 저하 현상을 최소화하기 위해 지속적인 영상 품질 개선 작업을 수행하고 있다. 본 논문에서는 KOMPSAT-3A 개발 단계에서 정의된 발사 전후의 검보정 주요 과정 및 대표 영상 품질 인자인 MTF, SNR, Location accuracy 측정 방법을 설명하였다. 이를 바탕으로 발사 후 초기 LEOP Cal/Val이 완료된 이후 측정된 영상 품질 인자별 성능값과 최근 2016년부터 2020년 5월까지 KOMPSAT-3A호의 주요 품질 인자인 MTF, SNR, Location accuracy 현황과 특성을 기술하였다.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.725-731
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• 2009

Construction documents are recognized as an essential component for making a decision and supporting on construction processes. In construction, the management of project document is a complex process due to different factors such as document types, stakeholder involvement, document flow, and document flow processes. Therefore, inappropriate management of project documents can cause several impacts on construction work processes such as delay or poor quality of work. Several information and communication technologies (ICT) were proposed to overcome problems concerning document management practice in construction projects. However, the adoption of ICT may have some limitation on the compatibility of specific document workflow. Lack of understanding on designing document system may cause many problems during the use and implementation phase. Thus, this paper proposes the framework that integrates Soft System Methodology (SSM) concept and Integrated Definition Modeling Technique (IDEF) for analyzing document management system in construction project. Research methodology is classified as the case study. Five main construction building projects are selected as case studies. The qualitative data related to problems and processes are collected by interviewing construction project participants such as main contractors, owners, consultants, and designers. The findings from case study show the benefits of using SSM and IDEF. The use of SSM can help identify the problems in managing construction document in rich picture view whereas IDEF can illustrate the document flow in construction project in details. In addition, the idea of integrating these two concepts can be used to identify the root causes of process problems at the information level. As the results, this idea can be applied to analyze and design web-based document management system in the future.

• 한국산업정보학회논문지
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• 제10권3호
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• pp.48-56
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• 2005

본 논문에서는 패킷 손실율과 왕복 시간을 사용하여 기존 방식보다 효과적인 네트워크 종단간 동적 흐름 제어 알고리듬을 제안한다. 패킷손실율이 평균값이하이면 현재 네트워크 상태는 왕복시간을 사용하여 결정된 3가지 상태중 하나로 결정되며, 이것은 심각한 패킷 손실이 발생하기 전에 보다 정확한 대역폭 제어를 할 수 있게 한다. 만약 패킷손실율이 임계값이상이면 현재 네트워크상태는 혼잡상태가 된다. 적당한 전송률은 이들 네트워크의 각 상태에 따라 결정되며, 이때 프레임의 품질 뿐만 아니라 전송 프레임 숫자를 동시에 조절한다. 본 논문에서는 제안된 알고리듬에 대한 실험 결과를 보였다. 정량적 실험결과를 통하여 제안 방식이 기존 방식보다 1.6배에서 6배의 성능 향상을 나타냄을 보였다. 동시에 총 전송 패킷수 역시 증가되었음을 보였다. 이로써 제안 방식이 기존 방식보다 향상된 대역폭 성능을 나타냄을 알 수 있었다.

• 대한전기학회논문지:전력기술부문A
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• 제49권6호
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• pp.253-258
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• 2000

This paper presents an application of Kohonen neural networks to assess the dynamic security of power systems. The dynamic security assessment(DSA) is an important factor in power system operation, but conventional techniques have not achieved the desired speed and accuracy. The critical clearing time(CCT) is an attribute which provides significant information about the quality of the post-fault system behaviour. The function of Kohonen networks is a mapping of the pre-fault system conditions into the neurons based on the CCTs. The power flow on each line is used as the input data, and an activated output neuron has information of the CCT of each contingency. The trajectory of the activated neurons during load changes can be used in on-line DSA efficiently. The applicability of the proposed method is demonstrated using a 9-bus example.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(5)
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• pp.173-176
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• 2001

In this treatise information communication indust based change phenomenon of payment system of money explain and study and compare way ago value that use electronic comnunity of the world and presented correct electron money model in real condition of our country. Draw payment way that consider particular situation and korean situation and that wi introduce electron money model of the world and analyze merits and demerits and is money here upon. Electron money introduction of smart card way that support all off-line and on-line that I currency and the nearest topology here direction must is insisting and relate in use of this or presenting value of money flowchart and draw the validity and hangup by introducing electronic mono model who is presenting in Kyong-gi Province and Su-won current and go forward group. Proposed suitable electron money system in Korea situation by proposing money form and model of payment system that can satisfy all this at 1 situation and physical special quality of mon by conclusion and clarify flow of the value.

• 한국정보통신학회논문지
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• 제6권4호
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• pp.552-558
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• 2002

차별 서비스 모델은 IP 기반 네트워크에서 서비스 품질을 제공하기 위한 새로운 구조 모델이다. RIO 는 차별 서비스 네트워크 환경에서 라우터의 큐 관리 메커니즘으로 가장 널리 적용되고 있다. 본 논문은 패킷 길이에 따른 처리율의 영향을 완화하는 개선된 RIO 메커니즘을 제안한다. 트래픽 조절 기능인 TSW 기능과 결합하여 시뮬레이션을 수행한 결과, 제안된 메커니즘은 적절히 배치된 네트워크 상황에서 패킷 길이에 무관하게 안정된 처리율을 보장하고, 대역폭의 공평한 분배를 제공하는 것으로 분석된다.

• 한국지능시스템학회논문지
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• 제14권1호
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• pp.69-74
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• 2004

A sequencing problem is to find an ordered sequence of some entities which maximizes (or minimize) the domain specific objective function. As some typical examples of sequencing problems, there are traveling salesman problem, job shop scheduling, flow shop scheduling, and so on. This paper introduces a new type of sequencing problems, named a sequencing problem with fuzzy preference relation, where a fuzzy preference relation is provided for the evaluation of the quality of sequences. It presents how such a problem can be formulated in terms of objective function. It also proposes a genetic algorithm applicable to such a sequencing problem.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권10호
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• pp.5079-5099
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• 2018

Regarding to the huge number of connections and the large flow of data on the Internet, Intrusion Detection System (IDS) has a difficulty to detect attacks. Moreover, irrelevant and redundant features influence on the quality of IDS precisely on the detection rate and processing cost. Feature Selection (FS) is the important technique, which gives the issue for enhancing the performance of detection. There are different works have been proposed, but a map for understanding and constructing a state of the FS in IDS is still need more investigation. In this paper, we introduce a survey of feature selection algorithms for intrusion detection system. We describe the well-known approaches that have been proposed in FS for IDS. Furthermore, we provide a classification with a comparative study between different contribution according to their techniques and results. We identify a new taxonomy for future trends and existing challenges.