• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.267-272
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• 2002

The electric heat pump requiring HCFCs as a refrigerant has been for most residential air-conditioners in Korea. They cause a surge up electric power demand during summer. Moreover, the use of HCFCs and HFCs causes a serious problem to the global environment such as global warming and ozone layer destruction. An absorption chiller and heater could solve such problems. It was built and tested for analyzing the performance of the absorption chiller/heater. Experiment was done with a 1.5RT household absorption chiller and heater. It was experimented that the cooling capacity, gas capacity, COP were researched by the temperature of cooling water. The change of the cooling water temperature have effect the temperature(or pressure) of the parts on absorption chiller The result of the change of the cooling water temperature have the effects of the absorption chillers. This data will help to operate the household absorption chiller and heater.

• Current Optics and Photonics
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• v.2 no.1
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• pp.90-95
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• 2018

Stimulated polariton scattering from the $B_1$-symmetry modes of a $KNbO_3$ crystal to generate a terahertz wave (THz-wave) with a noncollinear phase-matching scheme is investigated. The frequency-tuning characteristics of the THz-wave by varying the phase-matching angle and pump wavelength are analyzed. The expression for the effective parametric gain length under the noncollinear phase-matching condition is deduced. Parametric gain and absorption characteristics of the THz-wave in $KNbO_3$ are theoretically simulated. The characteristics of $KNbO_3$ for a terahertz parametric oscillator (TPO) are compared to those of $MgO:LiNbO_3$. The analysis indicates that $KNbO_3$ is an excellent optical crystal for a TPO, to enhance the THz-wave output.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.3
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• pp.149-157
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• 2010

The electromagnetic characteristics of FCEVs (fuel cell electric vehicles) are much different from the existing combustion engine cars as well as hybrid, plug-in-hybrid, and pure electric vehicles due to the high voltage/current generated by a fuel cell stack which uses a compressed hydrogen gas reacted with oxygen. To operate fuel cell stack efficiently, BOP (Balance of Plant) is essential. BOP systems are used many not only for motors in water pump, air blower, and hydrogen recycling pump but also inverters for these motors. Since these systems or components are connected by high voltage cables, EMC (Electromagnetic compatibility) analysis for high voltage/current cable is the most important element to prevent the possible electric functional safety errors. In this paper, electromagnetic fields of high current/voltage cable for FCEVs is studied. From numerical analysis results, time harmonic magnetic field strength of high current/voltage cable have difference of 20～28 dB according to phase. EMI result considered ground effect of FECV at 10 m shows difference of 14.5 dB at 30 MHz and 2.8 dB at 230 MHz compared with general cable.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.1
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• pp.1-7
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• 1998

Due to the increase in capacity of auxiliary machinery in power plant, the importance of energy saving has been greatly emphasized. If the speed of fans or pumps is controlled in accordance with the variation of load, large electric energy can be saved. Large capacity inverter, 2MVA GTO inverter, has been developed by operating two of 1MVA unit inverters in parallel. The parallel operation of the unit inverter is accomplished through two output transformers of which the secondary windings are connected in series. The system is composed of one control cubicle, one rectifier cubicle and 2 unit inverter cubicles. This inverter system was applied to the sea water lift pump(SLP) driven by a 6.6KV 1500KW induction motor in Seo-Inchon power plant to save the electric energy. The parallel operation of inverters by 180 degrees apart in switching frequency helps to reduce the harmonic components.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2006.04a
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• pp.145-148
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• 2006

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.243-247
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• 2005

Hydraulic performance test was conducted for a fuel pump of a liquid rocket engine turbopump. The pump driven by an electric motor was tested in water environment. It is experimentally shown that the inducer had very small effect on the pimp's head and efficiency but great effect on the pump's cavitation performance. Additionally, inducer test was carried out to investigate the effect of the inducer on the pump in detail, and it was found that the pump had a critical cavitation number when the inducer head dropped by $55\%$.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1157-1163
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• 2008

Fuel represents a significant portion of the operating costs of voyages of the vessel. Under this situation, dramatic increase in fuel price caused a problem that earnings of ship becomes decreased seriously. Pumps in a cooling system of the vessel are often operated inefficiently. The reasons will vary from process to process and application to application. Inefficiency of pumps is one of the reason for making the cost of operating the vessel increased. This paper suggests energy-effective cooling system that controls sea water pumps with inverters to reduce energy consumption in vessel by conducting simulation with LabVIEW. Results shows that electric energy consumption of pumps are significantly deceased. If this energy-effective cooling system is applied to other systems which need cooling, it could be useful in reducing electric energy wastage.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.296-299
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• 2008

In the present research, the exclusive analysis system based on the CFD method were suggested to predict the fire-suppression performance of water mist fire-suppression equipments for design applications. The computing scope is ranged from starting pump to fire-suppression equipments, composed of three parts that calculation of flow rate and pressure distribution at each nozzle, examining of spray performance and predicting of fire-suppression performance in the fire space. Application were done to the fire-suppression system for electric power generation plants. The results were analyzed by comparison between numerical results and initial design conditions in terms of thermal and fluid mechanics.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.383-397
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• 2012

In this study, a System Dynamics (SD) simulation model for the efficient operations of an industrial water supply system was developed by investigating the feedback loop mechanisms involved in the operations of the system. The system was modeled so that as demand is determined the water supply quantity of intake pumping stations and dams are allocated. The main feedback loop showed that many variables such as the combinations of pump operation, unit electric power(kWh/$m^3$), unit electric power costs(won/$m^3$), water level of water way tunnel, suction pressure and discharge of pumping station, and tank and service reservoir water level had causal effects and produced results depending on their causal relationship. The configurations of the model included an intake pumping station model, water way tunnel model, pumping station model (including the tank and service reservoir water level control model), and unit electric power model. The model was verified using the data from the case study industrial water supply system that consisted of a water treatment plant, two pumping stations and four dams with an annual energy costs of 5 billion won. It was shown that the electric power costs could have been saved 7~26% during the past six years if the operations had been based on the findings of this study.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.1
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• pp.9-16
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• 1983

흔히 자동차용 belt를 단순한 소모품으로 생각하여 대수롭지 않게 여기는 경향이 있으나 belt slip에 의한 동력의 손실은 매우 큰 것이며 특히 자동차용 belt에 있어서 그 중요성은 상당한 것이다. 왜냐하면 crankshaft에서의 중력이 belt를 통해서 water pump나 air compressor등에 전달되며 이때 동력전달이 제대로 안되는 경우에는 engine은 냉각수와 냉각팬에 의해 냉각이 되지 않아서 금방 고은소착 되기 때문이며, 또한 belt를 너무 조이는 경우에는 water pump bearing의 파손 등을 초래하기 때문에 belt의 정확한 길이 계산이 매우 중요하다. 그러나 이러한 중요성에도 불구하고 belt의 설계계산을 행하는 데는 많은 시간이 걸리며, 간혹 잘못 계산을 하는 경우에는 큰 문제가 발생할 수도 있기 때문에 belt계산의 기본이론식들을 전부 computer program 화하여 시간의 절약과 계산의 오류를 피하고자 한다. Program을 만들기 위해서 사용한 computer는 micro-computer로서 PET (Personal Electric Transactor)2001이며 사용한 언어는 BASIC이다.