• 통합자연과학논문집
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• 제2권2호
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• pp.101-130
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• 2009

In recent years, South Korea has often witnessed damages by gusts caused by thunderstorms in summer. The Korea Meteorological Administration defines that a gust happens when the maximum instantaneous wind velocity is 10m/s or more and draws up hourly observation reports. When a cumulonimbus develops due to an ascending current and reaches the height of 12~16 km, the temperature of the cloud top drops and a lightening happens, which causes a gust accompanied by a thunderstorm and further regional meteorological damage. It's difficult to predict a regional gust with the mesoscale prediction model at the administration. Thus this study set out to analyze the damage cases by a gust accompanied by a thunderstorm and to make a contribution to the prediction and understanding of a gust by a thunderstorm. A gust by a thunderstorm happens where potential equivalent temperature converges or is higher than the surrounding areas. The convergence area of potential equivalent temperature matches the track of thunderstorm cells. The Kimje gust took place where high potential equivalent temperature converged, and the Jangsu gust did as the area of high potential equivalent temperature approached. There should be a good amount of vapor supply with the moisture flux converging at the bottom layer in order to bring instability. In addition, it should collide into a dry and cold atmosphere at 700 hPa. The moving track at the center of the low dew point spread corresponds to that of a gust.

• Journal of Power Electronics
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• 제8권2호
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• pp.121-130
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• 2008

This paper introduces a design and implementation of a digital control unit for an Oxygenaire Servo Baby Incubator. The control unit is designed and implemented according to international standards. The control unit is based on an AVR Atmel microcontroller unit. It is built for monitoring and control and displays the three main temperature values: set point temperature, baby skin temperature and air temperature. User friendly software is implemented. The implemented control unit was tested in the laboratory as well as in the field. The control unit is sensitive to change of $0.1^{\circ}C$. At startup, based on a unique control strategy, the incubator reaches its steady state in about 14 minutes. The system schematic diagrams are shown in the paper. Also, programs flow charts are presented. The control unit was designed and implemented based on a contract between the Electronics Research Institute (ERI) and ENGIMED Company. The authors would like to thank ERI and ENGIMED for introducing all required finance and shoring to complete this work.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 추계학술발표회논문집(2)
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• pp.669-674
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• 1996

The theory of quantum mechanics states that for any system there are a set of discrete physical states, quantum states, which corresponds a particular energy level of the system. The lowest energy the system can have, corresponding to its ground state, is not necessarily zero, but depends only on the precise microscopic nature of the system under consideration. At the absolute zero of temperature all systems will be in their lowest energy state (zero point energy) and as the system is warmed from OK, the higher energy states become occupied. The probability of occupancy of the excited states relative to that of the ground state is proportional to the absolute temperature. Therefore we can obtain nuclear dipole and quadrupole moment very accurately at ultra low temperature (<15mk) by NMR and from the destruction of anisotropy. The former is called LTNO/NMR and the latter is called LTNO (Low Temperature Nuclear Orientation). In this paper we discuss and introduce only an experimental apparatus with results of cooling power test, a helium dilution refrigerator, which can reache 8mK, and an actual technique for the experiment, a theory and results will be presented in another papers.

• Journal of the Korean Wood Science and Technology
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• 제36권6호
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• pp.41-48
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• 2008

본 연구에서는 소나무 원목의 열처리 시 소요에너지에 대해 분석하였다. 소나무재선충 감염목에 대한 적절한 열처리는 소나무 재선충의 감염 확산을 막고, 감염목의 용재로서의 사용 가능성을 높인다. 본 연구에서는 병해충 감염목의 FAO 열처리 기준(International standards for phytosanitary measures (ISPM) No.15)에서 제시한 병해충 사멸 조건인 '목재 중심부 온도를 $56^{\circ}C$에서 30분 유지'를 위하여 소요되는 에너지를 평가하였다. 열처리에 소요되는 총 소요에너지는 초기 열처리 설정조건 도달에 필요한 처리기 벽체 가열, 처리기 내 공기 가열, 목재가열, 습도유지, 벽체 열손실로 구성되는 초기소요에너지와 열처리 설정조건 도달 이후의 열손실 보완 소요에너지, 즉 목재가열, 습도유지 및 처리기 벽체 열손실을 보완하기 위한 열손실 보완 에너지로 구분하였다. 단위시간당 초기소요에너지는 열처리 설정조건 도달 이후의 단위시간당 열손실 보완 에너지량보다 크며, 설정조건도달 이후의 단위시간 당 소요에너지는 거의 일정한 값을 가졌다. 시험결과 실험조건에 있어서 건조 온도와 더불어 상대습도가 매우 큰 영향을 미쳤으며 목재조건으로는 함수율 차이에 의해 변하는 밀도가 큰 영향을 미쳤다. 고온과 높은 상대습도 및 낮은 함수율, 즉 낮은 밀도가 열처리 속도를 증가시켰다. 이 연구를 통하여 소나무재의 열처리에 있어서 보다 효율적인 에너지 관리 방안을 마련할 수 있을 것으로 기대된다.

• 한국산학기술학회논문지
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• 제16권10호
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• pp.6759-6765
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• 2015

본 연구에서는 자연외기를 활용하여 건물의 중앙냉방시스템에 대한 에너지를 절약하기 위한 제어방법으로서 외기온도 조건을 고려한 나이트 퍼지제어의 적용방안에 대해 시뮬레이션 연구가 수행되었다. 외기온도의 변화특성 및 건물의 축냉성능 등이 고려되었으며, 나이트 퍼지제어를 위한 운전시작시간과 제어설정온도의 선정방안이 연구되었다. 본 연구를 위하여 TRNSYS 프로그램을 활용하여 시스템 해석 모델링을 수행하였으며, 기존 제어방식 대비 제안된 제어방법의 에너지 절약성능을 비교 분석하였다. 연구결과로 외기온도 변화에 따라 나이트 퍼지제어를 위한 운전조건을 선정한 제안된 제어방법이 기존의 나이트 퍼지제어 제어방식과 비교하였을 때는 최대 16.8%, 나이트 퍼지제어를 적용하지 않은 경우에 비해서는 최대 28.6%의 에너지 절감이 가능함을 알 수 있었다.

• 한국자동차공학회논문집
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• 제20권2호
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• pp.21-29
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• 2012

A dual loop waste heat recovery system with Rankine steam cycles for the improvement of fuel efficiency of gasoline vehicles has been investigated. A high temperature loop (HT loop) only recovers the heat of the exhaust gas. A low temperature loop (LT loop) recovers the residual heat from the HT loop, the coolant heat and the remaining exhaust gas heat. The two separate loops are coupled with a heat exchanger. This paper has dealt with a layout of the dual loop system, the review of the working fluids, and the design of the cycle. The design point and the target heat recovery of the HT boiler, a core part of a HT loop, have been presented. The prototype of the HT boiler was evaluated by experiment. For the performance evaluation of the HT boiler, inlet temperature of the HT boiler working fluid was set equal to the temperature degree of sub-cool of $5^{\circ}C$ at the condensing pressure. The exit condition was the degree of super-heat set at $5^{\circ}C$. The characteristics of the HT boiler such as heat recovery and pressure drops of fluids were evaluated with varying flow rates and inlet temperatures of exhaust gas under various evaporating pressure conditions.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.613-616
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• 2008

Assessment of geothermal resources like other earth resources is a starting point for decision makers or stakeholders to set up basic plan on its development and R&D policies. In this context, there have been various works on world geothermal assessment, to report different estimates from each other. In this paper, we first introduce the definition of geothermal potential mainly adopted from the article by Muffler and Cataldi (1978) and then summarize the estimates made so far referring the work by Bertani (2003). An updated estimates by Stefansson (2005) are also reviewed in terms of identified resources separately for high-temperature resources for power generation and low-temperature ones for direct-use. Recent estimate of US geothermal resources by MIT (2006) using a volumetric method with extensively accumulated data base is discussed. Finally, we introduce the first geothermal assessment in Korea recently made and discuss its importance.

• 설비공학논문집
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• 제23권5호
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• pp.327-333
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• 2011

In the present work, a new freeze protection method has been proposed for a natural circulation system of solar water heater. Though electrothermal wire is popularly used for the purpose, there are freezing troubles by wire cut-off and shortage of excessive electric power consumption. In the experimental device, hot water in storage tank was used to heat the outlet pipe from the tank if the pipe surface temperature falls lower than a set point. The cold water pipe to the storage tank was installed to directly contact the hot water pipe surface temperature rose by transferred heat.

• 한국생물환경조절학회:학술대회논문집
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• 한국생물환경조절학회 1995년도 특강 및 학술논문발표요지
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• pp.60-63
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• 1995

우리나라 기상여건을 고려하여 온실의 여름철 고온에 대한 체계적인 연구는 아직 미비한 상태이며 거의 이루어지고 있지 않다. 더우기 많은 자본과 기술이 투자된 현대화 하우스에서 여름철 고온화현상에 대처하는 재배기술부족으로 7, 8월 2개월간 작물을 재배하지 못하고 대부분 휴작을 하므로서 시설의 주년이용과 고도활용에 심각한 문제점으로 대두되고있으며 온실의 주년재배를 위한 여름철의 하우스환경의 적정화연구는 온실재배의 당면과제라 할수 있다. (중략)

• 한국지열·수열에너지학회논문집
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• 제13권4호
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• pp.8-13
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• 2017

The effects of operational conditions of cooling water system on energy consumption for central cooling system are researched by using TRNSYS program. Cooling tower water pump flow rate, cooling tower fan flow rate, and condenser water temperature with various dry-bulb and wet-bulb temperatures are varied and their effects on total and component power consumption are studied. If the fan maximum flow rates of cooling tower is decreased, cooling tower fan and total power consumptions are increased. If the cooling tower water pump maximum flow rates is decreased, chiller and total power consumptions are increased. If condenser water set-point temperature is increased, chiller power consumption is increased and cooling tower fan power consumption is decreased, respectively.