• 사물인터넷융복합논문지
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• 제9권3호
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• pp.1-6
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• 2023

웹 서비스 환경에서 사용자가 원하는 서비스 품질을 만족하는 경제적인 방법의 하나는 객체의 크기를 조절하는 것이다. 이를 위해 본 연구에서는 서비스 품질로 평균 응답 시간이 임의의 임계값 이하로 주어질 때, 이 제약 조건을 만족하는 최대 객체의 크기를 구한다. 시스템이 정상 상태일 때, 라운드-로빈을 사용하는 결정 모델의 평균 응답 시간은 일반 분포를 따르는 큐잉 모델에서의 평균 응답 시간과 같아질 것으로 추론할 수 있다. 이를 기반으로 최대 객체 크기를 발견하기 위한 해석적 수식과 절차를 수립한다. 웹 트래픽은 서비스 분포로 Pareto 분포가 적합하므로 M/G(Pareto)/1 모델과 지수 분포를 사용한 M/G/1/PS를 적용하여 최대 객체의 크기를 구한다. 수치 계산을 통한 성능평가는 Pareto 분포의 형상 파라미터(shaping parameter)가 커짐에 따라 M/G(Pareto)/1 모델과 M/G/1/PS 모델의 최대 객체 크기가 같아짐을 보여준다. 본 연구의 결과는 경제적인 웹 서비스 제어를 위해 객체의 크기를 조절하는 환경에 사용될 수 있다.

• 한국생산제조학회지
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• 제9권5호
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• pp.127-134
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• 2000

This paper presents the development of a semi-active seat damper using MR fluids and the performance analysis of seat suspension system with a MR seat damper. An annular orifice type MR seat damper is proposed for a seat suspension of a commercial vehicle. After formulating the governing equation of motion, then an appropriate size of the seat damper is designed and manufactured. Following the evaluation of field-dependant damping force characteristics, the controllability of the damping force is experimentally demonstrated in time domain by adopting PID controller. A semi-active seat suspension with the proposed MR damper is constructed and its dynamic model is established. Subsequently, vibration control capability of the semi-active suspension system is investigated by employing the sky-hook controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.244-246
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• 2006

Softwares in railway system are being used in the area of railway control system, directly associated to safety. Because the instinct characteristic of Software is uncertainty, Software development without safety insurance is very hazardous situation. In order to derive safety certification process in the railway system, certification and approval processes in the nuclear, aviation, and military area are studied. Software quality should be improved by two aspects : one is product aspect, another is process aspect. GS(Good Software) and ES(Excellent Software) certification can be exemplified in a product aspect approach. In those process certification, CMMI (Capability Maturity Model Integration) or SPICE (Software Process Improvement and Capability dEtermination : ISO/IEC15504) is being used as models for assessing process maturity of organization. Following the studies, safety management procedure in the railway system is suggested.

• 한국통신학회논문지
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• 제16권4호
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• pp.309-318
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• 1991

본 논문에서는 기준신호와 응답의 편차를 억제하기 위해서 이용하는 적분기와 직류전동기를 본드그래프로 구성하여 직류전동기의 속도 제어계에서 관성이나 외란 그리고 부하변동에 의한 파라미터나 응답변동에 대해서 높은 적응성을 갖는 모델추종형 servo 제어기를 본드그래프로 설계하였으며 이 본드그래프 모델링기법이 제어기의 동작 해석 및 설계에 유효함을 확인하였다.

• 한국대기환경학회지
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• 제10권1호
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• pp.49-56
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• 1994

Electrostatic Precipitators( EP ) are widely used in industry for controlling the emission of particulate pollutant Recently, a number of researches have been conducted to solve performance and reliability problems of EP, As a result of researches in the laboratory and of pilot scale, a technology of wide-pitch-spacing has been successfully applied to full scale units. It has been known that the wide-pitch-spacing can reduce the capital cost of newly installed precipitators, and the cost of rebuilding existing uints. In this paper, a systematic study was performed to develop a wide-pitch electrostatic precipitator. The study includes experimental and numerical work on the following : Particle collection characteristics for a bench-scale unit; gas flow characteristics( temperature and velocity distributions): other EP operating variables such as electric Power supply/control. The results are applied directly to design of wide-pitch-spacing EP and the developed numerical model was found to be a good argreement with the experimental results. The EHD simulation program is necessary to design the high efficiency EP.

• 한국경영과학회지
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• 제18권3호
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• pp.51-63
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• 1993

We consider a cyclid server system under N-policy. This system consists of multiple queues served in a cyclic order by a single server. In this paper, we consider the following control policy. Every time server polls one queue, the server inspects the state of the queue. If the total number of units is found to have reached or exceeded a pre-specified value, the server begins to serve the queue until it is empty. As soon as the queue becomes empty, the server polls next queue. An approximate analysis of this system is presented. Sever vacation model is used as an analytical tool. However, server vacation periods are considered to be dependent on the service times of respective queues. The results obtained from the approximate analysis are ompared with simulation results.

• 대한전기학회논문지
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• 제36권6호
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• pp.381-389
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• 1987

This paper presents a method for optimal load shedding in preserving a system security following abnormal condition as well as a sudden major supply outage. The method takes account of static characteristic of generators control and voltage and system frequency characteristic of loads. The optimization problem is solved by a gradient technique to get the maximal effect by the least quantity of load shedding considering line overloads as well as voltage disturbances and system frequency. The method is illustrated on a 8-bus system. It has been found that the use of the proposed algorithm for model systems alleviate the line overload more efficiently than the former method. It is believed that this method will be useful in security studies and operational planning.

• International Commerce and Information Review
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• 제2권1호
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• pp.49-68
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• 2009

In 2003, the Uniform Commercial Code(UCC) which is a kind of model law to unify commercial law between several states in US was amended to use electronic document of title including bill of lading. It is the second following the Australia legislation in 1996. Also, the Korean government amended Commercial Act and made the Presidential Decree for using electronic bill of lading in 2008. In this paper the authors reveal the characteristics of the clause of UCC for electronic bill of lading. The characteristics of the clause are on the technical neutrality of the signature, the possibility of reissuance in alternative medium, and adoption of the concept of "control." It helps to suggest some implications for Korean government authority. The authors suggest the amendment of the Presidential Decree to the Korean government authority to use additionally digital signature authorized by non Korean government such as VeriSign. It will activate the use of electronic bill of lading issued by Korea repositary out of Korea.

• 통상정보연구
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• 제11권2호
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• pp.281-300
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• 2009

In 2003, the Uniform Commercial Code(UCC) which is a kind of model law to unify commercial law between several states in US was amended to use electronic document of title including bill of lading. It is the second following the Australia legislation in 1996. Also, the Korean government amended Commercial Act and made the Presidential Decree for using electronic bill of lading in 2008. In this paper the authors reveal the characteristics of the clause of UCC for electronic bill of lading. The characteristics of the clause are on the technical neutrality of the signature, the possibility of reissuance in alternative medium, and adoption of the concept of "control." It helps to suggest some implications for Korean government authority. The authors suggest the amendment of the Presidential Decree to the Korean government authority to use additionally digital signature authorized by non Korean government such as VeriSign. It will activate the use of electronic bill of lading issued by Korea repositary out of Korea.

• 대한치과교정학회지
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• 제5권1호
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• pp.21-24
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• 1975

The purpose of this study was to investigate the effect of sinc phosphate cement on the enamel surface of extracted teeth. The tooth was placed in a test tube, which was subjected to 5ml of 0.2M acetate buffer at pH 4 by 'window technique.' The calcium content of the acetate buffer was determined by the Perkin-Elmer Model 303 Atomic Absorption Spectrophotometer. The obtained results were summarized in the following. 1. The solubility of enamel is $0.92mg/cm^2$. ml in control group. 2. The solubility of enamel is increased by treating these with zinc phosphate cements. 3. The solubility of enamel is $0.69mg/cm^2$. ml by treating with Lee Smith cement. 4. The solubility of enamel is $0.30mg/cm^2$. ml by treating with G-C's cement.