• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.579-586
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• 2011

During a reactor normal operation, a primary coolant was designed to remove the fission reaction heat of the reactor. When one pump is failure and the other pump shall supply the cooling water to cool the reduced power, it is necessary to estimate how much flow will be supplied to cool the reactor. We carried a flow net work analysis for two parallel pumping system as based on the piping net work of the primary cooling system in HANARO. As result, it is estimated that the flow of one pump increased than the rated flow of the pump below the cavitation critical flow.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.337-339
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• 1998

This paper deals with the design and fabrication of a novel superconducting power supply system, and characteristics have been analyzed through experiments. Superconducting power supply consists of rotating and static parts, and superconducting magnet. In this experiment, the current-pumping characteristics have been analyzed with superconducting sheets placed in parallel within the static part of the machine. In addition, in order to observe the 3-dimensional flux distribution in the superconducting sheet, several hall-sensors were placed in it. With the flux distribution acquired, the effect of the flux on the superconducting sheet during the process of current pumping have been analyzed. Also, general operational characteristics of the superconducting power supply system have been investigated on the basis of the current and voltage data and magnetic field values acquired through the experiments. In this experiment, maximum pumping current has been achieved to about 1280 amps.

• 한국자동차공학회논문집
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• 제19권2호
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• pp.26-34
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• 2011

Hybrid powertrain systems have been developed to improve the fuel efficiency of internal combustion engines. In the case of a parallel hybrid powertrain system, an engine and a motor are directly coupled. Because of the hardware configuration of the parallel hybrid system, friction and the pumping losses of internal combustion engines always exists. Such losses are the primary factors that result in the deterioration of fuel efficiency in the parallel-type hybrid powertrain system. In particular, the engine operates as a power consumption device during the fuel-cut condition. In order to improve the fuel efficiency for the parallel-type hybrid system, cylinder deactivation (CDA) technology was developed. Cylinder deactivation technology can improve fuel efficiency by reducing pumping losses during the fuel-cut driving condition. In a CDA engine, there are two operating modes: a CDA mode and an SI mode according to the vehicle operating condition. However, during the mode change from CDA to SI, a serious fluctuation of the air-fuel ratio can occur without adequate control. In this study, an air-fuel ratio control algorithm during the mode transition from CDA to SI was proposed. The control algorithm was developed based on the mean value CDA engine model. Finally, the performance of the control algorithm was validated by various engine experiments.

• 한국전산유체공학회지
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• 제17권4호
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• pp.1-8
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• 2012

During a reactor normal operation, two parallel 50% capacity cooling pumps circulate primary coolant to remove the fission reaction heat of the reactor through heat exchangers cold by a cooling tower. When one pump is failure, the other pump shall continuously circulate the coolant to remove the residual heat generated by the fuels loaded in the reactor after reactor shutdown. It is necessary to estimate how much flow rate will be supplied to remove the residual heat. We carried out a flow network analysis for the parallel primary pumps based on the piping network of the primary cooling system in HANARO. As result, it is estimated that the flow rate of one pump increased about 1.33 times the rated flow of one pump and was maintained within the limit of the cavitation critical flow.

• Journal of Mechanical Science and Technology
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• 제18권4호
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• pp.671-680
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• 2004

We present numerical and experimental results of the periodic flows inside a rectangular container under a background rotation. In numerical computation, a parallel-computation technique with MPI is implemented. Flow visualization and PIV measurement are also performed to obtain velocity fields at the free surface. Through a series of numerical and experimental works, we aim to clarify the fundamental reasons of discrepancy between the two-dimensional computation and the experimental measurement, which was detected in the previous study for the same flow model. Specifically, we check if the various assumptions prerequisite for the validity of the classical Ekman pumping law are satisfied for periodic flows under a background rotation.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권12호
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• pp.771-777
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• 2000

This paper deals with the design and fabrication of a novel superconducting power supply system, and characteristics have been investigated through experiments. Superconducting power supply consists of rotating and static parts, and superconducting magnet. In this experiment, superconducting foils were placed in parallel within the static part of the machine, pumping currents were measured with respect to rotor speeds and excitation currents. In addition, in order to observe the rotating flux distribution in the superconducting foils, several hall-sensors were placed in it. With the flux distribution acquired, effect of the flux on the superconducting foil during the process of current pumping has been discussed. Also, the general operational characteristics of the superconducting power supply system have been investigated on the basis of the current and voltage data, and magnetic field values acquired through the experiments.

• International Journal of Air-Conditioning and Refrigeration
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• 제15권3호
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• pp.114-121
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• 2007

In this study, a modified reverse flow type, one of the triple effect absorption cycles, is studied for performance improvement. The cycle simulation is carried out by using EES(Engineering Equation Solver) program for the working fluid of $H_2O/LiBr$ solution. The split-ratios of solution flow rate, UA of each component, pumping mass flow rate of solution are considered as key parameters. The results show that the optimal SRH (split ratio of high side) and SRL (split ratio of low side) values are 0.596 and 0.521, respectively. Under these conditions, the COP is maximized to 2.1. The optimal pumping mass flow rate is selected as 3 kg/s and the corresponding UAEV A is 121 kW/K in the present system. The present simulation results are compared to the other literature results from Kaita's (2002) and Cho's (1998) triple effect absorption systems. The present system has a lower solution temperature and a higher COP than the Kaita's modified reverse flow, and it also gives a higher COP than the Cho's parallel flow by adjusting split ratios.

• 자원환경지질
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• 제37권5호
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• pp.499-508
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• 2004

창원시는 전국에서 최초로 2001년에 북면과 대산면에 강변여과수 취수장을 건설하여 운영하고 있다. 본 연구는 창원시 북면 낙동강 본류 하안의 강변여과수 취수장 주변에 대해서 수리지질 특성을 평가하고 낙동강과 강변대수층간의 지하수유동 모델링을 수행하였다. 이를 통하여 강변여과수 취수에 따른 낙동강물과 지하수 유입량을 평가하였다. 지하수모델링에서는 시추자료, 입도분석자료, 양수시험분석자료, 지하수위 측정자료, 낙동강 수위 측정자료, 강수량 자료를 이용하였다. 정상류 모델링으로 강변여과수 취수 이전의 자연상태의 지하수위를 잘 모사할 수 있었다. 부정류 상태 모델링에서는 7개 취수정의 최대 양수량인 총 14,000$m^3$/day로 취수시의 지하수위 하강을 모사하였으며, 이때 낙동강으로부터의 유입량, 배후지쪽의 지하수 유입량 그리고 강변대수층의 동측과 서측으로부터 유입량은 전체 유입량의 각각 8,390$m^3$/day(60%), 590$m^3$/day(4%), 5,020$m^3$/day(36%)이다. 입자 추적 모사 결과, 낙동강쪽으로부터 취수정 쪽으로의 유입속도는 약 1.85m/day이고, 배후지로부터 취수정 쪽으로의 유입속도는 약 0.75m/day이다. 본 연구는 지표수/지하수 연계관리 모델링에 공헌하며, 강변여과수 취수량, 수질, 자연적인 함양량이 계절적으로 어떻게 영향을 받는지를 이해하는데 도움을 줄 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.244-246
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• 1999

This paper deals with the design and fabrication of a novel superconducting power supply system, and characteristics have been analyzed through experiments. Superconducting power supply consists of rotating and static parts, and superconducting magnet. In this experiment, the current pumping characteristics have been analyzed with superconducting sheets placed in parallel within the static part of the machine. In addition, in order to observe the rotating flux distribution in the superconducting sheet, several hall-sensors were placed in it. With the flux distribution acquired, the effect of the flux on the superconducting sheet during the process of current pumping have been analyzed. Also, general operational characteristics of the superconducting power supply system have been investigated on the basis of the current and voltage data, and magnetic field values acquired through the experiments.

• 상하수도학회지
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• 제19권4호
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• pp.487-496
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• 2005

Chlorine bulk decay tests were carried out by bottle test under controlled conditions in a laboratory. Experiments were performed at different temperatures: $5^{\circ}C$, $15^{\circ}C$, $25^{\circ}C$, and the water temperatures when samples were taken from the effluent just before entering to its distribution system. 38 bulk tests were performed for water of Al (water treatment plant), 4 bulk tests for A2 (large service reservoir), and A3(pumping station). Residual chlorine concentrations in the amber bottles were measured over time till about 100 hours and bulk decay coefficients were evaluated by assuming first-order, parallel first-order, second-order. and $n^{th}-order$ reaction. The $n^{th}-order$ coefficients were obtained using Fourth-order Runge-Kutta Method. A good-fit by the average coefficient of determination ($R^2$) was first-order ($R^2=0.90$) < parallel first-order ($R^2{_{fast}}=0.92$, $R^2{_{slow}}=0.95$) < second-order ($R^2=0.95$) < $n^{th}-order$ ($R^2=0.99$). But if fast reaction of parallel first-order bulk decay were applied to the effluent of large service reservoir with ca. 20 hours of travel time and slow reaction in the water distribution system following the first 20 hours, parallel first-order bulk decay would be best and easy for application of water quality modeling technique.