• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1046-1050
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• 2000

The necessity of diagnosis of the rotating machinery which is widely used in the industry is increasing. If rotating machinery has fault, we can detect fault using vibration or noise. But, in diagnosing rotating machinery, the end user who doesn't have expert knowledge needs the help of vibration diagnosis expert. However, vibration diagnosis experts who well satisfy the demand of end user are rare. So, this paper propose a development of the case-based reasoning system for abnormal vibration diagnosis of rotating machinery we construct the past experiences of vibration diagnosis expert into case base and shear the experiences of diagnosis expert with the end user. In this paper, we describe that process of structured system and adapting result of abnormal vibration diagnosis of electric motor.

• 한국통신학회논문지
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• 제32권6A호
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• pp.588-599
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• 2007

This paper presents the coexistence issues between M-WiMAX TDD and WCDMA FDD systems. To improve the M-WiMAX system performance and to reduce the adjacent channel interference to WCDMA FDD system, transmit and receive beamforming techniques are applied in the base stations of M-WiMAX system. Furthermore, we propose an adjacent channel interference modeling methodology, which captures the effect of transmit beamforming on the adjacent channel interference. Besides, we verify the performance improvement in the uplink of WCDMA system due to the transmit beamforming in M-WiMAX downlink based on the proposed adjacent channel interference modeling methodology. We also verify the performance enhancement due to the receive beamforming in the uplink of M-WiMAX system through system level Monte Carlo simulations, considering random user position, the effect of shadowing and multi-path fading channel. Discussions on the gain of applying transmit and receive beamforming in M-WiMAX system comparing the case of SISO system are also included. Furthermore, we present the performance of cosited M-WiMAX and WCDMA systems, considering commercial deployment, additional channel filter at base stations and the effects of TxBF and RxBF.

• 산업경영시스템학회지
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• 제32권1호
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• pp.147-156
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• 2009

The introduction and application of IT(Information Technology) to a company has become to be viewed as a key factor for the business competitiveness and improved productivity. This study presents an approach to evaluation of a company's informatization level, which is especially appropriate for small and medium enterprises. The proposed evaluation method, based on the traditional questionnaire approaches, considers the various characteristics of the company, e.g., types of business, characteristics of customers, and locations of supply chains etc. A web-based system was developed to enable users to obtain the evaluation results from the evaluation method. The system also provides a function to produce valuable strategies for informatization by utilizing the case base which will be cumulated by repetitive evaluation requests. Finally, a real case was analyzed in order to verify the practicality of the evaluation system.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1993년도 춘계공동학술대회 발표논문 및 초록집; 계명대학교, 대구; 30 Apr.-1 May 1993
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• pp.109-118
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• 1993

This paper describes the management of knowledge base and optimization models using knowledge-assisted optimization model formulation system UNIK-OPT (UNIfied Knowledge-OPTimization). We will illustrate UNIK-OPT with the case of production scheduling in refinery.

• 정보기술응용연구
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• 제1권
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• pp.99-127
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• 1999

최근 기업의 생산성 향상을 위한 설계 및 생산 환경의 분산화에 따른 원격지 공동설계의 필요성이 증대되고 있다. 마찬가지로 선박설계 과정도 그 과정이 매우 복잡하고 많은 양의 데이터를 다루고 있는 작업으로서 그 환경이 분산화, 이질화됨에 따라 최근 들어 CSCW (Computer Supported Collaborative Work)의 요구가 증대되고 있다. 본 논문에서는 분산된 선박설계 환경에서의 원격지 공동설계를 지원하기 위한 에이전트기반 선박설계 시스템을 개발하였다. 특히 여기서는 에이전트간의 정보교환 및 지식공유 과정에서 발생하는 의사충돌 문제를 해결하기 위하여 사례기반 추론 기법을 이용하여 이의 해결을 시도하였다. 설계 에이전트, 이들을 중재하는 퍼실리테이터, 충돌 처리기, 그리고 사례기반 시스템의 유기적인 도움을 받아 설계자는 설계과정에서 발생하는 설계 시스템간의 의사충돌 문제에 대한 의사결정을 과거의 유사한 문제해결 사례로부터 효과적으로 처리할 수 있다.

• 대한전기학회논문지:전력기술부문A
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• 제48권11호
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• pp.1457-1463
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• 1999

This paper develops an real-time expert system for the electronic interlocking system. it obtains the higher safety by determining the railway interlocking strategy in order to prevent trains from colliding, and derailing in the viewpoint of veteran expert, considering the situation of station in real-time. The expert system determines the real-time interlocking strategy by confirming the interlocking relationships among signal facilities based on the interlocking knowledge base from input information such as signal, points, and it is implemented as the rule-based system in order to represented accurately and effectively the interlocking relationships. Especially in case of emergency the function which determines the rational route coordinating with IIKBAG on the workstation is designed in order to minimize the spreading effect. It is implemented in C computer language for the purpose of the implementation of the inference engine using the dynamic memory allocation technique, the build and interface of the station structure database. And, the validity of the built expert system is proved by simulating the diversity cases which may occur in the real system for the typical station model.

• 대한임베디드공학회논문지
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• 제5권3호
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• pp.118-127
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• 2010

Inter-vehicle communication is one of the most important parts in Intelligent Vehicle System. Through this communication, drivers can recognize what is happening out of their sights, such as the freezing condition of the street, traffic accidents, and so on. Each car in IVS gives various services to the drivers after analyzing those received information from cars or a base station. If the message is, however, exchanged from car to car directly, the computation cost which is needed for all the car to authenticate the transmitted message between nearby cars is tremendously high. Therefore, one can naturally think that the message communication between cars is performed with the help of the base station to reduce the computation cost. In this case where the base station collects all the information transmitted from cars and broadcasts them nearby, there should be an efficient way both for the base station to authenticate the car message within its communication range and for the car to authenticate the information received from the base station. In this paper, we present a two-way authentication protocol using a hash chain to efficiently exchange GPS information between a car and a base station. This information can be used to provide a driver with the navigation which displays all the moving cars around him in real time. When a car goes into an area of a base station, the car authenticates itself to the base station using its private key of PKI, sends a commitment of a hash chain, then starts to send a message with the hash value for authentication. The message includes GPS information, driver's status and so on. The base station also authenticates itself to the nearby cars using its private key, transmits the commitment of the hash chain, and sends all the messages gathered from cars with authentication information.

• 물과 미래
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• 제18권1호
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• pp.85-94
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• 1985

수치해법와 경험적 방법을 합성함으로써 하천수문곡선의 기저유출을 분리하는 방법을 개발하였다. 기저유출 감수곡선에 대해서는 선형화된 Boussinesq 방정식과 저유함수를 적용하였으며, 또한 강우에 의하여 지하의 대수층에 침투된 량이 하천으로 유입되는 기저유출의 추정에는 Singh과 Stall의 도식적 방법을 이용하였다. 이들에대한 시간별 연속성은 다원적인 다항식 회귀론에 의하여 근사화시켰다. 본 연구과정은 자연하천에 성공적으로 적용할 수 있었으나, 감수곡선을 위한 동차선형2단상징분계의 직접적 수치해법은 부적합한 것으로 나타났으며, 손실이 발생되는 부분침투천의 기저유량은 본 연구방법에 의하여 추정할 수 없었다.

• Journal of Communications and Networks
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• 제6권3호
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• pp.226-234
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• 2004

This work presents a deterministic channel that rules according to inverse a power propagation law. The proposed channel model allows us to derive the lower bound and upper bound of packet's capture probability in Rayleigh fading and shadowing cellular mobile system. According to these capture probabilities, we analyze the system performance in the case of finite stations and finite communicated coverage of a base station. We also adopted a dynamic backoff window size to discuss the robustness of IEEE 802.11 draft standard. Some suggestions and conclusions from numerical results are given to establish the more strong CSMA/CA protocol.

• 산업경영시스템학회지
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• 제34권4호
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• pp.114-119
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• 2011

Process capability indices (PCls) have been widely used in manufacturing industries to provide a quantitative measure of process potential and performance. The previous studies have measured only one location on each part in the case of single variate. To calculate the reliable process capability, a couple of measuring locations on each part are required. In this paper, we propose a new system process capability index $SC_{pm}$ (m) which is the minimum value of the location PCls.