• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.444-446
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• 2003

This paper deals with an allocation strategy for the resources of direct load control program, which is considered the operating states in power systems. The existing approaches, load shedding priority algorithm, curtailment payback based algorithm and mixed curtailment algorithm, are based on the uniform allocation strategy. These approaches are not taken into account the operating states in power systems. So, under the critical operating condition, direct load control resource is evaluated by introducing the congestion factor.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.625-633
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• 2011

Characteristics of a commercial metal hydride (MH) hydrogen supply system have been investigated and an operating strategy was developed based on the experimental data. As a prior step, charging/discharging capacity, thermal properties such as heat capacity, heat of reaction of MH system were experimentally measured. And then P-C-T data for various operating conditions were collected and a correlation between P, C and T predicting the behavior of MH was derived. Based on the basic experimental data, an operating strategy of MH system was developed, in which the hot water temperature supplied into the water jacket of MH was controlled depending on the pressure of MH, thereby the pressure of MH could be maintained at a suitable range. By adjusting the temperature of hot water from $40^{\circ}C$ to $60^{\circ}C$, the maximum discharging capacity of hydrogen could be increased by 4.7%, and consequently more stable hydrogen supply and longer operation time of fuel cell system could be achieved.

• 한국자동차공학회논문집
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• 제8권3호
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• pp.85-97
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• 2000

In this paper, static and dynamic shift control stategies of CVT speed ratio are suggested. For the static shift control, in order to operate engine on the optimal operating region, a fuzzy control logic is used. In the fuzzy logic, S- factor that is defined as a degree of sportiness is introduced. Simulation results show that the static shift control strategy based on the fuzzy logic selects the optimal operating point automatically between the economy and the sporty mode corresponding to the driver's desire and the driving condition. For the dynamic shift control strategy, a shift speed map is suggested which determines the shift sped as fast or slow based on Δi, the difference between the desired speed ratio id and the actual speed ratio i, and throttle opening. It is seen from the simulation results that the CVT shift speed is determined by the dynamic shift control strategy to provide appropriate performance and comfort for the driver's demand and driving condition. Additionally, experiments are performed to investigate the dynamic performance of the shift speed for the lift foot up. From the experimental results, it is found that improved shift feeling can be obtained by the dynamic shift control strategy when lift foot up occurs.

• 한국항해항만학회지
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• 제35권3호
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• pp.271-279
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• 2011

국제적으로 기업활동의 수직적 분화와 현지경영이 가속화 됨에 따라 국제특송시장규모가 확대되고 있다. 글로벌 특송기업들은 확대되고 있는 국제물류시장에서 점유율을 증대시키고자 M&A를 통해 대형화하고 글로벌화하고 있는 데 반하여 우리나라 특송업체들은 규모의 영세성으로 국제물류시장에서 경쟁에 밀리고 있다. 본 연구에서는 우리나라 국제특송업체의 현황을 진단하고 경쟁력을 제고할 수 있는 방안을 탐색하고자 하였다. 연구결과에 의하면 국제특송산업의 특성요인과 이러한 시장에서의 경쟁적 특성요인이 특송업체의 두 유형의 글로벌 전략에 중요한 영향을 미치고 있는 것으로 나타나고 있다. 첫 번째 유형의 전략은 특성화전략(SCM전략, 3자물류전략, 토탈물류전략 및 차별화전략)이며 두 번째 유형의 전략은 M&A와 종하물류기업화에 의한 규모확대와 단계별 시장진출전략이다. 이러한 두 유형의 전략이 제대로 실행되어야만 국제특송업체의 경쟁력을 증대시킬 수가 있으며 이를 위한 정부의 체계적인 지원이 필요한 것으로 나타나고 있다.

• Journal of Electrical Engineering and Technology
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• 제4권4호
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• pp.515-520
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• 2009

According to the operating characteristics of pump applications, they should exhibit high efficiency and energy saving capabilities throughout the whole operating process. A novel efficiency optimization control strategy is presented here to meet the high efficiency demand of a variable speed Permanent Magnet Synchronous Motor (PMSM). The core of this strategy is the excellent integration of mended maximum torque to the current control algorithm, based on the losses model during the dynamic and the grade search method with changed step by fuzzy logic during the steady. The performance experiments for the control system of a variable speed high efficiency PMSM have been completed. The test results verified that the system can reliably operate with a different control strategy during dynamic and steady operation, and the system exhibits better performance when using the efficiency-optimization control.

• Journal of Power Electronics
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• 제17권5호
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• pp.1317-1326
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• 2017

The cascaded H-bridge (CHB) multilevel converter is a promising topology for large-scale photovoltaic (PV) systems. The output voltage over-modulation derived by the inter-module active power imbalance is one of the key issues for CHB PV systems. This paper proposed a dynamic power distribution strategy to eliminate the over-modulation in a CHB PV system by suitably redistributing the reactive power among the inverter modules of the CHB PV system. The proposed strategy can effectively extend the operating region of the CHB PV system with a simple control algorithm and easy implementation. Simulation and experimental results carried out on a seven-level CHB grid-connected PV system are shown to validate the proposed strategy.

• Journal of Power Electronics
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• 제18권1호
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• pp.225-233
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• 2018

This paper proposes a universal system control strategy for voltage source converter (VSC) based high voltage direct current (HVDC) systems. The framework of the designed control strategy consists of five layer structures considering the topology and control characteristics of the VSC-HVDC system. The control commands sent from the topmost layer can be transmitted to the next layer based on the existing communication system. When the commands are sent to each substation, the following transmission of commands between the four lower layers are realized using the internal communication system while ignoring the communication delay. This hierarchical control strategy can be easily applied to any VSC-HVDC system with any topology. Furthermore, an integrated controller for each converter is designed and implemented considering all of the possible operating states. The modular-designed integrated controller makes it quite easy to extend its operating states if necessary, and it is available for any kind of VSC. A detailed model of a VSC-HVDC system containing a DC hub is built in the PSCAD/EMTDC environment. Simulation results based on three operating conditions (the start-up process, the voltage margin control method and the master-slave control method) demonstrate the flexibility and validity of the proposed control strategy.

• 대한조선학회논문집
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• 제57권3호
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• pp.152-159
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• 2020

Ship owners had pursued higher benefits by demanding the new design and construction of ships with higher operational efficiency. There was a necessity for shipyards to suggest a more economical design and advanced operation concept in order to meet the demands. Especially, since BOG combustion and activation of the re-liquefaction unit had to be taken into account in ship design in addition to fuel oil and gas consumption, the evaluation of the operating efficiency considering the technological trends was necessary. In this paper, it was aimed to study the design philosophy and operation strategy by considering the effect of fuel oil and gas consumption, BOG combustion, and activation of the re-liquefaction unit on the operating cost for laden voyage according to ship speed, BOR, and activation of the re-liquefaction unit. For this purpose, the costs were acquired by conducting the sailing simulation of an LNGC based on a mathematical model including the maneuvering equations of motion. The design philosophy and operation strategy was reviewed in terms of the operating cost.

• 식품과학과 산업
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• 제53권3호
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• pp.307-315
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• 2020

식품산업과 국내외 환경변화 등에 따라 식품 R&D 추진체계에 대한 변화가 필요한 시점에서 유망 식품산업 육성을 위한 미래지향적 식품 R&D 추진 및 식품산업정책과 연계한 R&D 추진전략을 제안하였다. 국내외 식품산업 동향 및 글로벌 트렌드 분석에 기초하여 미래지향적인 식품산업 성장을 위한 연구개발 분야의 전략적 대응방안을 정리하고, 식품산업 R&D 현황과 개선점을 검토하여 향후 식품산업 R&D 추진방향을 설정하였다. 식품산업 R&D 추진체계를 고도화하기 위해 구체적으로 효율적인 R&D 사업추진을 위한 연구기획체계 강화, 연구수행 주체간의 역할 분담 및 협업 강화, 미래 기술기반 확보, 현안문제 해결 및 산업현장 맞춤형 지원체계 강화, 정책사업 연계 및 식품 R&D 관리시스템 효율화 방안을 제시하였다.

• 대한기계학회논문집A
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• 제33권1호
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• pp.42-48
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• 2009

A design methodology for control strategy and control structure gives a direct impact on wind turbine's performance and life cycle. A baseline control law which is a variable rotor speed and variable pitch control strategy is introduced, and a mathematic performance model of a wind turbine dynamics is derived. By using a numeric optimization algorithm, the steady state operating conditions of wind turbines are identified. Because aerodynamic interaction of winds with rotor blades is basically nonlinear, a linearization procedure is applied to analyze wind turbine dynamic variations for whole operating conditions. It turns out the wind turbine dynamics vary much depending on its operating condition.