• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.371-377
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• 2002

근래 정보 시스템의 흐름은 생산 분야의 관리뿐만 아니라, 고객과의 관계를 중시하는 CRM(Costumer Relation Management)과 공급업체와의 협업 관계를 유지하는 eProcurement시스템에 초점을 맞추고 있다. 즉, 기존에는 단위 생산 시스템의 관리에 중점을 두었지만 최근에는 그 외부 요소들에 대한 관리의 중요성을 인식하게 되었고 이를 통징하여 공급망 관리(SCM Supply Chain Management)라고 한다. 본 논문에서는 공급망 관리에서 필요한 생산 계획수립 문제에 대해서 살펴본다. 특히 고객과의 관계에서 중요한 기능인 납기 회답을 지원하는 생산 계획 수립의 실행 주기에 대해서 살펴본다. 첫째, 단위 생산 시스템에서 사용하는 작업지시(Work Order)와 구매 지시(Purchase Order)를 생성하는 정규계획 모델에 대해서 설명한다. 정규계획 모델에서 필요로 하는 정적 정보와 동적 정보의 수집 및 계획의 실행을 담당하는 ERP 시스템과의 관계에 대해서 정의하고 정규계획 모델의 운영 주기를 정의한다. 둘째, 정규계획 모델과 상호 협조하면서 납기 회답을 지원하는 납기회답 모델의 설계에 대해서 살펴본다. 정규계획 모델과 달라지는 입력 부분의 정의와 정규계획 모델과의 상호 관계를 정의한다. 다음으로, 정해진 납기를 지키기 위해서 정규계획 모델에서 고려래야 하는 요소에 대해서 알아본다. 가장 중요한 것으로 작업 부하와 생산 용량을 고려한 계획 일자(PST)와 고객 납기와 제조 공정 LT를 고려한 계획 일자(LPST)중 최소값을 원자재의 납기 일자로 사용하는 것을 제안한다. 동시에 신규 구매 지시 계획을 생성하기보다는 기존에 발생된 구매 지시의 우선적 사용과 기존 구매 지시의 납기 일자를 고객 납기에 가장 잘 맞출 수 있도록 변경하는 방안을 제시한다. 이렇게 함으로써 최대한 고객 납기를 만족하도록 계획을 수립할 수 있게 된다. 본 논문에서 제시하는 계획 모델을 사용함으로써 고객 주문에 대한 대응력을 높일 수 있고, 계획의 투명성으로 인한 전체 공급망의Bullwhip effect를 감소시킬 수 있는 장점이 있다. 동시에 이것은 향후 e-Business 시스템 구축을 위한 기본 인프라 역할을 수행할 수 있게 된다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.42-51
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• 2007

An AC electrical railroad system has rapidly changing dynamic single-phase load, and at a feeding substation, three-phase electric power is transformed to the paired directional single-phase electric power. There is a great difference in electrical phenomenon between the load of AC electrical railroad system and that of general power system. Electric characteristics of AC electrical railroad's trainload are changed continuously according to the traction, operating characteristic, operating schedule, track slope, etc. Because of the long feeding distance of the dynamic trainload, power quality problems such as voltage drop, voltage imbalance and harmonic distortion my also occur to AC electrical railroad system. These problems affect not only power system stability, but also power quality deterioration in AC electrical railroad system. The dynamic simulation model of AC electrical railroad system presented by PSCAD/EMTDC is modeled in this paper, andthen, it is analyzed voltage drop for AC electrical railroad system both with single-phase distributed STATCOM(Static Synchronous Compensator) installed at SP(Sectioning Post) and without.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.187-188
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• 2011

This paper proposes the hybrid Complex-PSO algorithm based on the complex search method and particle swarm optimization (PSO) for unconstrained optimization. This hybridization intends to produce faster and more accurate convergence to the optimum value. These hybrid will concentrate on determining the dynamic load model parameters, the ZIP model and induction motor model parameters. Measurement-based parameter estimation, which employs measurement data to derive load model parameters, is used. The theoretical foundation of the measurement-based approach is system identification. The main objective of this paper is to demonstrate how the standard particle swarm optimization and complex method can be improved through hybridization of the two methods and the results will be compared with that of their original forms.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.3-4
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• 2006

본 논문에서는 계통의 불확실성을 고려한 확률론적인 방법으로 전력계통의 신뢰도를 평가한다. 발전기 3 state modeling 및 부하의 정규분포 곡선으로 확률론 신뢰도 평가 모델을 가정하였다. 그리하여 Adequacy 및 계통의 전압 및 송전선제약 조건 외에도, 소신호 안정도 항목을 추가하여 보다 동적인 측면에서의 신뢰도 평가가 이루어지도록 하였다. 이러한 평가 방법의 결과에 의하여 각 평가 항목간의 비율을 비교하였으며, 이를 통한 PSS의 설치 위치 선정의 근거를 마련하였다. 모의 방법은 Monte Carlo Simulation방법을 사용하였으며, WSCC 3기 9모선과 New England 10기 39모선을 모의계통으로 하였다.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.411-413
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• 2005

Static approaches usually employed in voltage stability analysis are based on the pre-determined scenarios of varying load and generation patterns. Thus, even though the approaches are applied to the same system condition, one may obtain different voltage instability phenomena using different scenarios. In the stage of concrete control strategy determination against voltage instability, dynamic approaches with full-time and/or quasi steady-state simulations need to be applied in order to confirm the effectiveness of the established control strategies. This paper describes the ULTC and dynamic load models, and discusses characteristics of the models.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.121-122
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• 2002

When a power system experiences a serious disturbance on insufficient power, the system frequency may drop. For system frequency will be maintain standard value, under_frequency relay will reconstruct balance of power and load by load shedding. Currently load shedding scheme is due to establishment plan by fixed scenario. Where compare current scheme with past scheme, system frequency should be recovered by load shedding using rate of frequency decline. This paper suggests the dynamic load shedding scheme by using the rate of change of frequency when The Korea Electric power system is happened the large disturbance.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.379-384
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• 2014

This article describes the dynamic behaviors of a rubber tired gantry crane(RTGC) under typical load conditions which are used in the design of gantry cranes. In order to investigate the dynamic characteristics of an RTGC, we developed a finite element crane model for its huge structure. The finite element model was validated with the modal test results, e.g., natural frequencies and normal modes. And other components of RTGC were converted into detailed 3D CAD models and finally transformed to rigid body models in a dynamic simulation program ADAMS. The load conditions considered in this paper were a normal operating condition(OP1) and container hanging condition with no external loads. As a result, we could find there was large influence of crane's vibration owing to its structural stiffness and deformation. And the vibration of crane could made the movements of RTGC, which occurs crash or malfunction of crane works.

• The Journal of the Korea Contents Association
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• v.8 no.5
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• pp.1-8
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• 2008

The centralized conference architecture, one of the conference architectures in SIP(Session Initiation Protocol) environment, is widely used as it has the advantage of conference management and control. However it has been limited in scalability. Therefore we have proposed an efficient distributed conference architecture to improve scalability of centralized conference model. In our architecture, if the number of conference participants exceeds the predefined maximum number, a new conference server is added to the conference dynamically. In this case, the focus of existing server acts as primary focus and the focus of added server acts as secondary focus, and dynamic reallocation of participants between servers is done to equally divide the loads. This process is repeated as the number of conference participants increases. For this behavior, we have proposed procedure of adding the conference server, SIP call signal exchange, signaling procedure for RTP(Real Time Transport Protocol) sessions between conference servers, and procedure of conference event package between conference servers. The performance of our proposed model is evaluated by experiments.

• Journal of the Korea Society of Computer and Information
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• v.9 no.1
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• pp.55-62
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• 2004

The computer security is considered important due to the side effect generated from the expansion of computer network and rapid increase of the use of internet. Therefore, Intrusion detection system has been an active research area to reduce the risk from intruders. A number of advantages of using mobile agent computing paradigms have been Proposed. These advantages include : overcoming network latency, reducing network load, executing asynchronously and autonomously, adapting dynamically, and operating in heterogeneous environments. Many information security models have been proposed to mitigate agent-to-agent. agent-to-platform, and platform-to-agent element risks . In these paper, We have an object which is that through intrusion detection system development, the mobile agent is managed and through the analysis of performance data. the best environment is served.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.1
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• pp.60-68
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• 1999

This paper deals with the tracking control problem of industrial robotic manipulators with unknown or changing dynamics. The proposed method makes use of multiple moodels and switching mechanism by fuzzy inference of the manipulator in an indirect adaptive controller architecture. The models used for the indmtification of the manipliator are identical, except for the initial estimates of the unknown inertial pararmeters of the manipulator and its load. The torque input that is applied to the joint actuators is determined at every instant by the identification model that best approximates the robot dynamics. Simulation results are also included to dermnstrate the improvement in the tracking perfermance when the proposed method is used.s used.