• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.4
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• pp.252-261
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• 2001

Room air flow and temperature distribution was numerically investigated where a PAC(personal air conditioning) system was installed. The calculated results were compared with those from experiments. The effects of the important operation parameters such as the air flow rate, velocity, and temperature at the diffuser on the thermal performance of the system were studied. The possibility of energy saving using the PAC system was verified from the results, It was shown that the warm air from the diffuser could not spread over the whole task area if the inlet temperature was too high.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.191-196
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• 2001

In the systems with largely pipe head loss, variable speed pumps are generally used because substantial energy saving can be expected from such systems by controlling pump speed and also they offer simpler maintenance and operational ease even in conditions where abrupt changes In flow rate and head can occur. The invertor or the fluid coupling system are mainly adopted to control the rotating speed. In this paper, operating conditions at Migum pressing pump station(5 stage), where the fluid coupling system was the first installed for KOWACO, are investigated and analysed so that information thus gained can be usefully employed in the efficient operation of variable speed pump in new installations of in-line booster pumping station.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.177-184
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• 2001

Combustion using oxygen enriched air is an energy saving technology that can increase thermal efficiency by the improvement of burning rate and high temperature flame. But information about it is not so enough yet. Flame figure, temperature distribution and emission concentration were measured with oxygen enriched concentration and swirl number in a turbulent diffusion flame to investigate the combustion characteristics. The results showed that flame figure became different as long as oxygen enriched concentration varied and that concentration of NO increased suddenly around $O_2$ 60%.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.101-106
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• 2002

In the Refrigeration and air conditioning industrial circles, refrigerator is demands a high degree of efficiency due to the Environmental Preservation Law. Many researchers are working on factors to improve the efficiency of the refrigerator In this paper, a study of the factors on the decrease of electric power consumption, several experiments are performed to improve the fluid flow in the refrigerator machine room. As a results, average temperatures of compressor and condenser are reduced 3.1$^{\circ}C$, 2.$0^{\circ}C$. The consuming electric power rate is reduced 0.7kWh/month.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1332-1336
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• 2009

If water-chillers are arranged in series-series counterflow, compressor lift of each chiller will be decreased in comparison with water-chillers in parallel. That means that compressor power of the chillers in series will be lower than that of chillers in parallel. However, the pressure drop of the water flow through the chillers in series will increase, and thus increase the power of water pumps. This disadvantage will be made good by increasing the temperature difference of water flow through evaporator and condenser, but the water flow rates will decrease. This paper explores the optimal parameters in system of series-series counterflow for central chilled water plants such as the leaving chilled water temperature, the leaving condenser water temperature, condenser water flow rate and number of chillers in series.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.863-866
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• 2005

Low-power design is one of the most important challenges encountered in maximizing battery life in portable devices as well as saving energy during system operation. In this paper we propose a low-power DCT (Discrete Cosine Transform) architecture using a modified Computation Sharing Multiplication (CSHM). The overall rate of power consume is reduced during DCT: the proposed architecture does not perform arithmetic operations on unnecessary bits during the Computation Sharing Multiplication calculations. Experimental results show that it is possible to reduce power dissipation up to about $7{\sim}8%$ without compromising the final DCT results. The proposed lowpower DCT architecture can be applied to consumer electronics as well as portable multimedia systems requiring high throughput and low-power.

• Journal of the Korean Society of Combustion
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• v.8 no.3
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• pp.1-7
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• 2003

Combustion using oxygen enriched air is an energy saving technology that can increase thermal efficiency by the improvement of burning rate and by the high temperature flame. Flame figures, OH radical intensities, temperature distributions and emission concentrations were measured according to oxygen enriched concentration and swirl number in a turbulent diffusion flat flame. It appeared that flame figure became flat and NO concentration decreased with increase of swirl number, and that the flame temperature increased high with increase of oxygen enriched concentration. In particular, it was most significant between oxygen concentration $40{\sim}60%$.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.97-104
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• 2002

The conventional regenerative system has a high thermal efficiency as well as energy saving using the high preheated combustion air. in spite of these advantages, it can not avoid high nitric oxide emissions. Recently, flameless combustion has received much attention to solve these problems. In this research, numerical analysis is performed for flow-combustion phenomena in the self regenerative burner. In this analysis we used Fluent 6.0 code. the that is developed for commercial use, Methane gas is used as a fuel and two-step reaction model for methane and Zeldovich mechanism for NO generation are used. the velocity of the preheated combustion air is used as a parameter and we analyze the characteristics of flow-field, temperature distributions and NO emissions. Due to the increased recirculation rate, the maximum temperature of flame is significantly increased and NOx emissions is reduced

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.333-339
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• 2000

This study was performed to investigate the performance of heat recovery device attached to exhaust gas funnel connected to combustion chamber of greenhouse heating system. The experiment heat recovery system is mainly consisted of LPG combustion chamber and two heat recovery units; unit-A is attached directly to the exhaust gas funnel, and unit-B is connected with unit-A. Heat recovery performance was evaluated by estimating total energy amount by using enthalpy difference between two measurement points together with mass flow rate of gas and/or air passing through each heat recovery unit depending on 5 different flow rates controlled by voltage meter. The results of this experimental study, such as heat exchange behavior of supply air pipes and exhaust air passages crossing the pipes, pressure drop between inlet and outlet, heat recovery performance of exchange unit, etc., will be used as fundamental data for designing optimum heat recovery device to be used for fuel saving purpose by reducing heat loss amounts mostly wasted outside of greenhouse through funnels.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.124-126
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• 2004

본 논문은 CAM(Constant Awake Mode), 및 PSM(Power Saving Mode)을 지원하는 IEEE 802.l1b[1] Infrastructure 환경에서 전송 프로토콜이 이동기기의 WNIC(Wireless Network Interface Card) 에너지 소비에 미치는 영향을 분석하고 단위 시간 동안 전송되는 데이터 양에 기반한 IEEE 802.l1b WNIC 에너지 모델을 제안한다. 제안하는 에너지 모델은 IEEE 802.l1b 환경에서 CAM 및 PSM 모드를 사용할때, 실제 측정한 값을 기반으로 설계되었다. 제안된 에너지 모델은 실험을 통하여 정확성을 검증하고, IEEE 802.l1b를 기반으로한 저전력 통신 관련 연구에서 시뮬레이션 시 사용 가능한 에너지 모델임을 밝힌다.