• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1154_1155
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• 2009

본 논문은 철도부하의 이동을 고려한 전력조류계산 알고리즘에 기반하여, 에너지 저장장치를 설치하였을 때 철도계통의 영향 해석에 관한 논문이다. 철도부하는 위치적 변화 뿐 만 아니라 기동-타행-제동의 운전모드의 변화에 따라 전력소비 패턴이 달라지는데, 제동 시에 발생하는 회생에너지를 에너지 저장장치를 이용하여 활용함으로서 에너지 절감 효과 및 가선전압 안정화를 구현할 수 있다. 본 논문에서는 서울지하철 2호선의 실계통에 대한 사례연구를 수행하여, 실계통에 에너지 저장장치를 적용함으로서 그 필요성을 증명하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.460-465
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• 2007

유출지하수는 지하공간이 깊고 넓게 분포하는 건물에서 자연적으로 유출되어 배출되는 낮은 심도의 지하수이다. 본 연구에서는 신축된 교회건물에서 유출되는 지하수를 열원으로 밀폐형태와 개방형태의 열교환기를 활용하여 각각 5RT급 히트펌프시스템을 난방모드로 운전한 결과를 정리하였다. 실험은 난방순환수의 온도를 $43{\sim}49$ $^{\cdot}C$ 범위에서 제어하면서 진행하였으며, 시스템 COP에 있어서 밀폐형은 $4.12{\sim}4.75$, 개방형은 $3.42{\sim}3.98$의 범위에서 측정되었다. 이는 기존의 지열히트펌프시스템의 COP와 대동 소이한 우수한 성능이라고 판단된다. 또한 펌프동력을 제외한 히트펌프 자체 난방COP에 있어서 밀폐형은 $4.69{\sim}5.81$, 개방형은 $4.38{\sim}5.43$의 범위에서 나타났다. 유출지하수의 온도가 겨울철에도 약 $12{\sim}14^{\cdot}C$를 유지하므로 히트펌프와 시스템전체의 COP가 매우 우수한 값을 나타내고 있음이 확인되었다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.340-343
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• 2007

In this paper, we present our method to reduce vibration of the base plate of a refrigerator by avoiding resonance between base plate and compressor operation. To verify the modes of the base plate, FE models of the base plate with free-free condition and applied boundary condition were built and validated by results from experimental modal analysis. Operating Deflection Shape analysis was applied to find the sensitive area on the base plate during compressor operation. In optimization process, Finite Difference Method - based sensitivity analysis is used to detect the most sensitive area. Finally, based on this numerical result, we will make beads on the base plate to reduce vibration of refrigerator.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1504-1506
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• 2004

The platform screen door(PSD) hasn't been installed yet within the manual operation system, that is, ATS & ATC Signal system. In other countries, it is mostly installed and operated within automatic operation system, that is, ATO. Especially, as a part of the environment friendly system installation, the installation of PSD shall be considered aggressively to improve the air quality in the underground area and to maintain the air-conditioning. Besides the number of suicides in the subway station gets increased these days causing safety hazard, so the installation of PSD is positively reviewed. To install PSD in the manual operation system, it is important to stop the train at the correct position. So we would like to suggest the technical system thereby.

• Progress in Superconductivity and Cryogenics
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• v.2 no.1
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• pp.31-34
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• 2000

this paper deals with the initial magnetic field decay for a large scale superconducting magnet e.g. NMR/MRI magnet. The high resolution image can not be obained during the periods of the initial field decay. It is known that all superconducting materials have the property of diamagnetism. This diamagnetism is usually explained with the concept of screening current. We assumed that the existence of the screening currebt. we assumed that the existence of the screening current makes the current distribution in the superconducting wire non-uniform. And the initial magnetic field decay is caused steady current state in the view of its pattern. The initial magnetic field decay is caused by the change of the current distribution between the energizing state and persistent current mode. in this paper the theoretical analysis for the current distributions has been introduced for each state. The experiments have been carried out to verify transport currents in order to veperiments, it small at the higher transport current.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.3
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• pp.457-465
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• 2004

Environmental protection on the ocean has been interested and nowadays the International Maritime Organization(IMO) has advanced on the prevention of air pollution from ships. This study presents the performance and the emission characteristics of 4 stroke marine diesel engines for generation application in D2 cycle(IMO mode). The effects of important operating parameters, such as intake air pressure. intake air temperature and maximum combustion pressure on NOx emissions were also described. Emissions measurement and calculation are processed according to IMO Technical Code. The results show that the maximum combustion pressure by fuel injection timing control and intake air temperature has strong influence on NOx emission production. But NOx emission is not affected by intake air pressure and exhaust gas back pressure.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.885-890
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• 2001

This simulation shows turbine trip on range mode, combined operation of 4 boilers and 5 turbines, for shoaiba desalination plant which is being operated in Saudi Arabia. In this model, unit master controller controls load demand, fuel and air flowrate to be consumed during operating of the plant. Feedwater controller controls drum level to compensate feedwater with superheater steam flow. This analysis was performed by constructing a dynamic model of the plant using ProTRAX and running it through the appropriate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.04a
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• pp.34-38
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• 1994

진동계측, 충격실험 및 진동해석등을 통하여 대형 다기능 공작기계(planomiller) 구조의 진동특성을 규명하고자 하였다. 정상적인 기존 모델에 대해 다양한 운전조건에서의 진동을 계측하여 그 주파수 특성으로부터 실험과 해석의 대상 주파수대역을 선정하고 주된 진동의 성분과 수준을 조사하여 향후 유사공작기계의 개발시 비교평가의 기준으로 삼고자 하였다. 또한 정지상태의 공작기계 구조물에 대한 충격시험을 통하여 실험 주파수응답함수를 구하고 이로부터 공작기계가 가지는 기본적인 고유진동수와 진동모드, 동강성 수준등을 파악하였다. FEM 모델에 대한 진동해석을 수행하여 실험결과와 비교함으로써 이러한 대형공작기계의 동특성 규명에 대한 해석적 예측의 가능성을 검토하였는데 특히 하부지지조건, 습동면 접촉부의 연결조건 및 감쇠력등이 동특성에 미치는 영향을 고찰하였다.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1226-1231
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• 2009

This paper presents operating characteristics of internal heat exchanger(IHX) for $CO_2$ geothermal heat pump in the heating mode. Mass flow rate of $CO_2$, inlet temperatures of $CO_2$ at high and low pressure side were selected as main effect factors by using fractional factorial DOE(Design of Experiments). And RSM(Response Surface Method) was used in optimization phase. The results show that heat transfer rate of IHX increases when either inlet temperature of low pressure side decreases or inlet temperature of high pressure side increases. Effectiveness of IHX increases with increasing of inlet temperature of either high pressure side or low pressure side. Finally, performance contour map was provided over the operation ranges of the main design factors.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.2
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• pp.166-171
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• 2010

Wired monitoring systems have been used for damage detection and dynamic analysis of large structures(bridges, dams, plants, etc.). However, the real-world applications still remain limited, mainly due to time and cost issues inherent to wired systems. In recent years, an increasing number of researchers have adopted WSN(wireless sensor network) technologies to the field of SHM(structural health monitoring). Accurate time synchronization is most critical for the wireless approach to be feasible for SHM purpose, along with sufficient wireless bandwidth and highly precise measuring resolution. To satisfy technical criteria stated above, a wireless vibration monitoring system that uses high-precision MEMS(micro-electro-mechanical system) sensors and A/D convertor is discussed in detail. It was found experimentally that the level of time synchronization fell within $200\;{\mu}sec$.