• Journal of Korea Society of Industrial Information Systems
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• v.28 no.6
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• pp.21-27
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• 2023

Modern naval ships install an Infra-Red Signature Suppression system (IRSS) in their exhaust pipe to reduce infrared signature emitted to the outside. In addition, naval ships are strategic assets with a very long life cycle, so high reliability of the performance of the equipment on board must be guaranteed. Therefore, equipment such as IRSS is evaluated for performance through model testing at the design stage. A variety of measuring instruments are used in IRSS model testing, and the reliability of these instruments must also be guaranteed. In this paper, a study was conducted to evaluate the reliability of measurement equipment used in IRSS model testing. The test equipment and instruments used were a hot gas wind tunnel, pitot tube, digital differential pressure gauge, thermocouple sensor, and digital recorder. As the fan speed of the hot gas wind tunnel increased, the measurement deviation of the flow decreased, and the temperature output of the thermocouple sensor showed differences in response time and stability depending on the method used.

• Journal of Korea Port Economic Association
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• v.26 no.1
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• pp.172-194
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• 2010

External costs emerge as a consequence of negative external effects. The EU commission and national government in Europe made themselves the internalization of external costs and began to make various measures. The traffic sector plays an important role. At the same time, it affects as financial loads to logistics service providers and carriers in Europe. This study examines current development in european logistic market conditions. It describes the reaction of different market players and stakeholders in the logistic value chain in EU, Switzerland and Germany. A portfolio of different strategic answers to the changing market environment is being developed. Therefore, different options for the internalization of external costs are proposed. This study finally derives propositions for future research.

• Korean Security Journal
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• no.56
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• pp.9-30
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• 2018

Crime prevention strategies are introduced to reduce the loss caused by crimes, and Target hardening against domestic burglary attacks is broadly accepted as one of such physical security strategies. In terms of business and home security, target hardening is one of the suite of protective measures that are included in crime prevention through environmental design(CPTED). This can include ensuring all doors and windows are sourced and fitted in such a way that they can resist forcible and surreptitious from the attack of intruder. Target hardening with certified security doors, security windows and secure locks are revealed to be much more effective to deter burglary attacks than other security devices, such as CCTV, lightings and alarms which have largely psychological and indirect impact. A pilot program of target hardening utilizing certified security window and locks was carried out in Ansan city, South Korea in 2016. This study is based on the quasi-experimental design of this program for a residential area. The researchers tried to verify the crime displacement effect of the target hardening program and the diffusion effects of crime prevention benefits by analysing the crime statistics. The evaluation utilized WDQ(Weighted Displacement Quotient) technique to analyze whether the crime displacement occurred, compared the crime statistics of the experimental area with that of buffer zone and controlled areas. The result showed that the target hardening program was significantly effective in crime prevention. The number of burglary in the experimental site with target hardening intervention reduced by 100%, although the areas without the intervention showed reduction in the burglary. The crime displacement was not found at all, and the number of burlary at the buffer zone also reduced significantly.

• Proceedings of the Korea Database Society Conference
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• 1997.10a
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• pp.504-514
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• 1997

관계형 데이터베이스의 성능을 향상시키는데 중요한 요소 중의 하나는 트랜잭션을 처리하기 위해 데이터를 디스크에서 주기억장치로 옮기는데 필요한 디스크 액세스(access) 횟수이다. 본 연구는 관계형 데이터베이스에서 트랜잭션을 처리할 때, 릴레이션(relation)을 수직분할하여 디스크에 단편(fragment)으로 저장하므로써 필요한 단편만 액세스하여 액세스 횟수를 감소시키는데 목적이 있다. 단편에 속성을 중복할당하여 수직분할하므로써 트랜잭션을 만족시키는 단편의 수를 감소시켜 중복할당을 고려하지 않은 방법보다 디스크 액세스 횟수를 감소시킬 수 있다. 갱신트랜잭션의 경우 하나의 속성이 갱신되면 중복된 속성을 모두 갱신하여야 하므로 액세스 횟수가 증가하지만, 조회트랜잭션의 경우 각 단편에 속성을 중복할당하여 액세스 횟수를 감소시킬 수 있다. 본 연구에서는 속성의 중복을 허용하여 단편을 구성하는 경우에 중복을 고려하지 않은 경우를 포함하므로 효과적으로 디스크 액세스 횟수를 감소시킬 수 있다. 본 연구에서는 중복할당을 고려하여 디스크의 액세스 횟수를 최소화시킬 수 있는 수직분할문제의 0-1 정수계획모형을 개발하고, 모형에 대한 최적해법으로 분지한계법을 제안한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.121-129
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• 2000

In this paper, we discuss how to operate a buffer yard in an automated container terminal, which will be used for resolving the difficulties to which the interaction between external manned trucks and internal unmanned equipment led. The determination of fleet size of material handling equipment is an important issue in designing of buffer yard in automated container terminals. This research also addresses the issue of determining buffer capacities through simulation. By using response surface methodology (RSM) for efficient experimentation, the optimal combination of design parameters under applicable operational strategies is obtained.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.403_404
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• 2009

전력은 공공재화로서 광역정전이나 전역정전이 발생하면 전력공급에 매우 심각한 문제가 발생하므로 이에 대한 합리적인 분석과 효과적인 대책 수립이 필요하다. 송전계통의 주 구성요소인 선로, 철탑, 변압기, 개폐장치들은 장기 사용에 따른 노후화와 같은 문제와 절연의 특성상 초고압전기 절연의 근원적 난점 등으로 다수의 절연파괴 고장이 불시에 발생하게 되어 전력공급의 신뢰성을 떨어뜨리게 된다. 이와 같이 전력기기들은 사전에 진단을 하여 기기의 상태를 알아내는 것이 필요하다. 주요 기기에 대한 진단은 데이터베이스의 구축과 이로부터 고장을 예측하고 신뢰성을 평가하는 것으로 이루어진다. 이를 위해 보다 정교하고 정확한 고장 예측 기술, 진단기술, 신뢰성 평가기술을 개발할 필요가 있다. 본 논문에서는 송전기기의 유지보수를 위한 기기 상태 추정 모델을 제시하고, 송전유지보수 전략 수립을 위한 방법을 제시한다.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.209-217
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• 2013

This paper presents a control strategy of 4 wheel drive (4WD) vehicles. Proposed control strategy has simple structure and can easily apply to various vehicles with low cost and time. It is consist of feedforward control for traction ability, fedback control for minimizing the wheel speed difference and yaw control for lateral stability. In addition, to integrate the traction and stability control, a blending function is applied. To evaluate the feasibility of the proposed control strategy, actual vehicle experiment is conducted after deciding the tuning parameter through the simulation. The simulation is accomplished by CarSim and Matlab/Simulink and the actual vehicle test is conducted using full size Sports Utility Vehicle (SUV) equipped rear wheel based solenoid type 4WD device.

• Venture DIGEST
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• s.87
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• pp.16-17
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• 2005

지난 11월 22일 코엑스 인터콘티넨탈호텔에서 '벤처기업 투명경영 실천포럼'이 개최되었다. 최근 일부 벤처기업의 분식회계 문제와 관련하여 건전한 기업경영을 하고 있는 대다수 벤처기업인들의 사기가 저하되고, 재무 및 회계투명성에 대한 인식제고의 필요성이 대두됨에 따라 마련된 이번 포럼에서는 각 분야 전문가들의 의견이 활발히 개진됐다 협회 조현정 회장의 개회사와 중소기업청 이승훈 차장의 격려사로 시작된 이번 포럼에는 벤처윤리위원회 강석진 위원장의 기조발제에 이어, 금융감독원 전홍렬 부원장의 '금융감동정책방향'. 다산회계법인 김일섭 대표의 '벤처기업의 회계투명성 제고', 한양대 한정화 교수의 '벤처기업의 위기관리 전략'에 관한 주제 발표와 PSIA 박상일 대표의 '우수사례'발표가 있었다. 포럼 내용을 간략하게 정리해 본다.

• Journal of the Korean Operations Research and Management Science Society
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• v.26 no.4
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• pp.143-153
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• 2001

In this study we develop a computer simulation model to evaluate the effects of various production and order processing policies measured in terms of on-time delivery rate and average waiting time of job orders. Policies considered include : eliminating inflated due date, lot splitting, loss time reduction, attaining full flexibility in production lines, and selective order promising scheme. Actual order-production data from a chemical company were used in the simulation model. Based on the simulation results, we make several suggestions that can significantly reduce the production lead time and increase the on-time delivery rate.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.266-268
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• 2006

In this paper, we design a Linear Quadratic Gaussian(LQG) controller for active suspensions. We can improve the inherent suspension problem, trade-off between the ride quality and the suspension travel by selecting appropriate weights in the LQ-objective function. Using an optimization-algorithm, Evolution Strategy(ES), we find the proper control gains for selected frequencies, which have major effects on the vibrations of the vehicle's state variables. The frequencies and proper control gains are used for the neural network data. During a vehicle running, the trained on-line neural network is activated and provides the proper gains for non-trained frequencies.