• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2004년도 하계학술발표 논문집
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• pp.224-224
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• 2004

• Journal of Biosystems Engineering
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• 제36권3호
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• pp.217-222
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• 2011

This study was carried out in order to reduce the amount of underground water which is used in the double layered single span plastic greenhouse for retaining heat. For this research, two plastic green houses of the double layered single span plastic greenhouse were installed. There was equipped of internal small tunnel for keeping warm air in the interior of the house. Then the internal small tunnel for keeping warm air was fitted with PVC duct of 50 cm in diameter filled with subsurface water. The surplus solar energy in the greenhouse was stored in the water in the PVC duct. Four FCUs (Fan Coil Unit), which has the capacity of 8,000 kcal per hour, were installed in the middle of the house, and a circulation motor in heat storage water tank was operated from 10:30 a.m. to 16:00 p.m. in order to circulate water between the water tank and the FCUs. Consequently about 5 degrees celsius could be maintained in the interior of the internal small tunnel for keeping warm air with the external temperature of lower than minus 5 degrees celsius. It appeared that the alteration of an internal temperature of the house was flexible depending on the sunlight during daytime. To prevent the water freezing, mixing antifreezing liquid in the water or operating FCU continuously was needed. Also, in order to use the surplus solar thermal energy on plastic green house of water curtain system efficiently, storing the surplus heat during daytime simultaneously finding a method of using water curtain systematic underground water happened to be important. As a result of this research, when the house's interior temperature is below zero the operation of FCU appeared to be impossible. Considering the amount of water used in the house with water-curtain-heating system is 150~200 ton per day, using the system mentioned in this research showed that reducing the underground water more than 80% in order to maintain the internal temperature as the level of 5 degree celsius at the extreme temperature of minus 5 degrees celsius.

• 한국지반신소재학회논문집
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• 제12권1호
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• pp.83-92
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• 2013

지중송전관로를 통한 송전용량 증대를 위해서는 송전 시 발생하는 열을 빠르게 소산시킬 수 있도록 습윤 시 $50^{\circ}C$-cm/Watt, 건조 시 $100^{\circ}C$-cm/Watt 이하의 열 저항률을 갖는 재료를 되메움재로 사용하는 것이 요구되며, 이를 위해 선행연구에서는 요구되는 조건을 만족시키는 열 소산 되메움재를 개발하였다. 이 연구에서는 개발된 열 소산 되메움재의 열 소산효과를 알아보기 위하여 1회선의 단면을 현장에 설치하고 개발된 열 소산 되메움재와 강모래, 현장토에 대하여 열을 직접 가하고 일정한 지점에서 온도를 측정함으로서 현장시험을 수행하였고, 시험결과와 유한요소해석과의 비교를 통해 열 소산효과를 비교하였다. 비교결과, 열원과 가까운 지점에서는 개발된 열 소산 되메움재가 강모래와 현장토에 비해 열평형상태에 빨리 도달하는 것으로 나타났으며, 열평형에 도달하는 온도도 높은 것으로 나타나 열 소산효과가 우수한 것으로 나타났다. 또한 다른 지점에서도 개발된 되메움재가 다른 재료보다 온도가 높아 열 소산효과가 우수한 것으로 나타났다. 또한 함수비의 변화에도 열 소산효과가 크게 변화하지 않는 것으로 나타났다.

• 농업과학연구
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• 제25권2호
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• pp.310-320
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• 1998

This study is aimed at identifying the socio-economic effects of storage of ginger in artificial caves. The gingers stored in artificial caves in Seochun, 12 sampled areas, were surveyed to get information on the socio-economic effects. The surveyed data were processed by TSP, Qbasic and B/C Ratio computer programs and analyzed the decision making criteria such as B/C ratio, NPV and IRR. The socio-economic effects of the storages of the gingers are as follows. 1. The storage benefits per ton was showed as 184,050won. 2. Considering 10% of the opportunity cost of capital, the uper limits of investments for the cave storages was analyzed as 6,784 thousand won for ginger. 3. The investment of the natural cave storages was revealed economically feasible considering the decision making criteria as B/C ratio = 1.33, NPV = 35.059 thousand won and IRR = more than 100%. The other socio-economic effects of the ginger storages was expected as ; 1. The cave storages will contribute to increase consumer's and producer's welfare through the control of supply and demand and price stability. 2. Long-term storage of ginger without damaging quality and grades will be made on account of the storage conditions as relatively low temperature, high humidity and indifferent affects from the outside climate. 3. Utilization of the underground space, the caves, for storage will maximize the land use and the sustainable environment considering the mountainous area, two third of the total national land area. 4. Construction costs of the underground storage facilities as caves are cheaper than the ground storage facilities by 15 to 20% in general. In conclusion, the underground space like natural and artificial caves are considered the most suitable for storage of ginger on account of the storage conditions as temperature, humidity and blocking the sun light. Accordingly a study on convenient utilization of new development of artificial caves should be made considering transportation and input-output of the farms. Financial support of the government should be institutionally rearranged for the successful implementation of storing farm products like ginger in natural and man-made caves.

• 한국터널지하공간학회 논문집
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• 제14권3호
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• pp.197-213
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• 2012

디스크커터는 암석의 절삭을 위해 TBM에 사용되는 핵심 굴착도구이다. 본 연구에서는 디스크커터에 의한 암석의 절삭 시에 커터 링에 발생하는 변형특성을 파악하기 위하여, 경암에 대한 선형절삭실험 시에 커터 링에 부착한 일련의 변형률게이지와 적외선 열화상 카메라에 의한 계측을 실시하였다. 실험결과, 커터 링은 매우 뚜렷한 선형탄성 거동을 보였으며, 암석 절삭에 의한 커터 링의 온도 상승은 $14.4^{\circ}C$ 이내로 나타났다. 따라서 본 연구에서 수행한 선형절삭실험 조건에서는 절삭으로 인한 커터 링의 변형과 온도상승이 크지 않았음을 알 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 하계학술대회 논문집
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• pp.304-307
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• 1990

Referring to the calculation of the continuous permissible current rating in 22.9kV CN/CV underground distribution power cables, the current and temperature have been fully discussed and analyzed based on their three different values: one is the actually measured value throughout our test and the other two are calculated in connection with different specifications IEC-287 and JCS-168-D respectively. For this purpose, our test has been carried out with real cables which have been under stress either with induced current or with rating voltage. In the former, the calculated current of IEC-287 shows closer value to the measured one than that of JCS-168-D does. In the latter, there has been little difference on the temperature comparing with that measured without voltage application. Therefore, we think that it is preferable to choose the IEC-287 specification for the calculation of the continuous permissible current rating in the commercially power cables.

• 한국태양에너지학회 논문집
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• 제30권2호
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• pp.87-95
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• 2010

This study analyzed the performance of solar chimney system for natural ventilation in underground space. A mathematical model of the solar chimney was proposed in order to predict its performance under varying parameters and Korea climatic condition. Steady state heat transfer equations were set up using a energy balanced equations and solved using a inverse matrix method. Numerical simulation program to analyze system was developed by using MATLAB. As the results, the ventilation performance of the solar chimney was determined by the temperature difference of air channel and inlet, and the temperature difference was influenced by insolation, stack height and distance of air gab. Also the solar chimney system can provide $262.9m^3/h$ of annual average ventilation rate. Because seasonal differences of ventilation rate was calculated within 25%, the solar chimney system can be used for every season in Korea climatic condition. Through this study, performance of solar chimney system for natural ventilation was verified by numerical method. Consequently, the solar chimney system is proved to be effective device for natural ventilation utilizing at all times, and the additional studies should be made through the experimental method for imagineering and commercialization.

• 한국터널지하공간학회 논문집
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• 제12권4호
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• pp.341-347
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• 2010

터널화재 시 위험을 경감시키기 위해 설치하는 물분무설비의 성능을 실대 시험을 통해 확인하였다. A급 화재, Pool 화재 및 차량화재시 물분무노즐은 뜨거운 연기의 온도를 낮추는데 효과가 큰 것으로 확인되었다. 또한 터널에 기류가 존재하는 경우에도 냉각효과가 큰 것으로 확인되었다. 이 결과를 통해 물분무설비는 터널화재 시 기류온도를 낮춤으로써 fire jump를 방지하고, 주위의 시설물을 보호할 수 있을 것으로 판단된다.

• 터널과지하공간
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• 제7권1호
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• pp.13-19
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• 1997

It is necessary to study on thermo-hydro-mechanical effect at rock mass performing project such as radiowaste disposal in deep rock mass. In this study, thermo-hydro-mechanical coupling analysis which is considered interaction and the variation of rock properties induced by temperature increase was performed for the circular shaft when appling temperature of 20$0^{\circ}C$ at the shaft wall. The shaft is diameter of 2 m and under hydrostatic stress of 5 MPa. In the cases, thermal expansion by temperature increase progress from the wall to outward and thermal expansion could induce tensile stress over the tensile strength of rock mass at the wall. When rock properties were given as a function of temperature, thermal expansion increased, tensile stress zone expanded. Lately, water flow is activated by increase of permeability and decrease of viscosity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.721-723
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• 2005

This paper analyses the characteristic of temperature and energy of oil field cable in transient state such as lightning surge. For analysis in various conditions, many actual underground power cable systems are modeled using ATP These results are applied for the examination of temperature increase when the hitting of lightning surge are occurred. The inner part temperature of OF cable is analysed according to the various kinds of cable using the thermal model of transient state. The temperature increase of sheath and crossbonded lead by fault current is also analysed using IEC 60949.