• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.369-371
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• 2002

The railway power feeding system is divided into AC power feeding system and DC power feeding system. In downtown area. DC power feeding system is used and AC power feeding system is used in intercity railway system. AC power feeding system raises a inductive disturbance that is divided into electrostatic induction and electromagnetic induction. Especially, it has a bad effect on communication lines. So inductive disturbance reduction method has been adopted in many system. In this paper, we deals with the inductive disturbance reduction method of railway power feeding system and of sides affected by inductive disturbance.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.359-361
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• 1987

It is known that the reactive component of AC power in the Power system gives no energy to outside and causes enlargement of power apparatus, voltage fluctuation and unstability of power system. The power conversion system and control system which are composed of power semiconductor devices such as Thyrisor, transistor, GTO and so on have been appeared as new sources of Harmonics. So the reduction of harmonics in power semiconductor system is one of impending problems on the point of energy conservation and improvement of power factor. This paper treates the fundamental review of the harmonics reduction by Current type PWM-Inverter. This Inverter-detects not only the fundamental wave but also that of all harmonics created in the power semiconductor system and is scheduled to control by sampled value.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.3
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• pp.251-257
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• 2000

District heating and cooling systems offer highly efficient energy utilization and maintenance by centralizing heat management. More pumping power, however, is required because the water has to travel long distance from heat source to the users. In the present study, a trace of drag reduction additives is added to the District Cooling system to achieve a significant drag reduction and save pumping power. Water-soluble polymers, surfactants, and environment-friendly degradable polymers are used as effective drag reducing additives. Time dependent percent drag reductions are compared for various additive solutions at 100 wppm concentration for different water velocity. Without as an anionic surfactant, copolymer was most effective in percent drag reduction. It is found that there exists an optimal condition when copolymer is mixed with SDS. An environment-friendly degradable polymer, xanthan gum, is found to be a significant drag reduction additive. Ice slurry systems, can give less pressure drops compared with chilled water system for certain condtions. Drag reduction additives were also effective for the ice slurry system.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.137-143
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• 2003

Annual radiation dose limit to radiation worker was substantially lowered in Korea by the adoption of 1990 recommendations of the International Commission on Radiation Protection (ICRP 60) in its legislation. On the other hand, radiation management environment in nuclear power plants is getting more worse because of the accumulation of radiation sources inside the system and the frequent need for maintenance according as the operation years of nuclear power plants increase. Therefore, Korea Hydro & Nuclear power Co., Ltd. (KHNP) has established a long-term 10 years plan from 2001 to 2010 for the reduction of radiation dose to workers. The plan is aimed for the reduction of annual dose per unit averaged over 5 years from 0.9 man-Sv in 2001 to 0.75 man-Sv in 2010 by radiation source reduction, equipment/tool improvement or new equipment development for easy maintenance, and the improvement of administration and system.

• KIEE International Transactions on Power Engineering
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• v.12A no.1
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• pp.1-5
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• 2002

This paper presents the procedure to construct equivalent model of large power system based on nonlinear time simulation responses. It consists of coherency identification, generator aggregation and network reduction. Coherency index that can be directly implemented to this procedure is proposed. Generator aggregation based on detailed model is performed. This procedure can be used to construct equivalent model in PSS/E. It is also possible to reduce the large power system directly from the nonlinear time responses. This procedure is applied to the transient stability analysis of Korea power system that now experiences rapid changes. The equivalent model is compared with the original model in its size, accuracy, speed and performance. This paper shows that the developed equivalent model is a good estimate of the original system.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.119-124
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• 2006

This paper deals with energy-saving effort in the hydraulic power steering system. Commonly, the hydraulic power steering systems are used for passenger cars and the reduction of pumping loss under non-steering condition is important to improve fuel economy. Experiments and simulations are performed simultaneously to examine the main factors to reduce the pumping loss-pressure loss and flow rate of the power steering systems. Fuel economy effect of the optimal design of power steering system is verified by vehicle test - more than 1% fuel consuming reduction is attained.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.2
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• pp.261-266
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• 2015

Power system for renewable energy is composed of module, transform DC power into AC power inverter, control power flow and device for a charge of the grid-connected. Power system for renewable energy produce the most DC power, when this system is much insolation in summer and daytime. But if the certain temperature rises above, the essential grid-connected power inverter is take a nose dive. There, in this paper, we propose an improved reduction of heating system. In addition, selection of the most serious heat region and through analysis of temperature characteristics according to location and distance derive the optimal model.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.1
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• pp.24-31
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• 2012

This study is designed to predict the overall electric power load, to apply the method of time sharing and to reduce simultaneous load factor of electric power when authorized by user entering demand plans and using schedules into the user's interface for a certain period of time. This is about smart grid, which reduces electric power load through simultaneous load factor of electric power reduction system supervision agent. Also, this study has the following characteristics. First, it is the user interface which enables authorized users to enter and send/receive such data as demand plan and using schedule for a certain period of time. Second, it is the database server, which collects, classifies, analyzes, saves and manages demand forecast data for a certain period of time. Third, is the simultaneous load factor of electric power control agent, which controls usage of electric power by getting control signal, which is intended to reduce the simultaneous load factor of electric power by the use of the time sharing control system, form the user interface, which also integrate and compare the data which were gained from the interface and the demand forecast data of the certain period of time.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.7
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• pp.1039-1046
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• 2017

Campus microgrid is designed and built by considering not only power generation but also power consumption management as connected microgrid type because the main goal of the campus microgrid is to save power consumption costs. There are many functions to achieve the goal and they are mainly to use generation-based functions such as islanding operation for peak management and for emergency events. In power distribution operation, Conservation Voltage Reduction (CVR) is applied in order to reduce power consumption. The CVR is defined as a function for load consumption reduction by voltage reduction in order to reduce peak demands and energy consumption. However, application of CVR to microgrid is difficult because the microgrid cannot control a tap of transformer in a substation and the microgrid normally is not designed with phase modifying equipment like a step-voltage-regulator which can control voltage in power distribution system operation. In addition, an impact of the CVR is depended on load characteristics such as a normal load, a rated power, and synchronous motors. Therefore, this paper proposes an application of CVR using linear voltage control based AVR in campus microgrid with power consumption reduction considering characteristics of load and component in the microgrid. The proposed system can be applied to each buildings by a configuration of power distribution cables; and the application results and CVR factor are presented in this paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1902-1910
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• 2009

This paper presents a graphical windows-based program for the education and training for novel network reduction. The object of developed simulator is to provide users with a simple and useable tool for gaining an intuitive feel for power system analysis. The developed simulator consists of the main module (MMI,GUI), the location marginal price module (LMP), the clustering module and network reduction module. Each module has a separate graphical and interactive interfacing window. The developed simulator needs with the PSS/E input data format, generator cost function, location information. Line admittances of reduced network was determined by using the power flow method(Newton-Raphson). So line flow of reduced network is almost same to original power system. Results of reduced network are compared on the window in the tabular format. Therefore, the developed simulator can be utilized as a useful tool for effective education and training for power system analysis.