• 한국초전도ㆍ저온공학회논문지
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• 제14권2호
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• pp.32-35
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• 2012

The objective of the present work is to develop a precise instrument for measuring the thermal property of insulating material over a temperature range from 30 K to near room temperature by utilizing a cryocooler. The instrument consists of two thermal links, a test sample, heat sink, heat source and vacuum vessel. The cold head of the cryocooler as a heat sink is thermally anchored to the thermal link and used to bring the apparatus to a desired temperature in a vacuum chamber. An electric heater as a heat source is placed in the middle of test sample for generating uniform heat flux. The entire apparatus is covered by thermal shields and wrapped in multi-layer insulation to minimize thermal radiation in a vacuum chamber. For a supplied heat flux the temperature distribution in the insulating material is measured in steady and transient state. The thermal conductivity of insulating material is measured from temperature difference for a given heat flux. In addition, the specific heat of insulating material is obtained by solving one-dimensional heat diffusion equation.

• 한국기계기술학회지
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• 제20권6호
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• pp.763-769
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• 2018

In this research, in order to improve the heat retention of greenhouse, comparative analysis of the heat flux of the marketed multi-later insulating curtain was carried out. Experiments is conducted by fabricating a test apparatus for investigating the heat flux characteristics. The multi-later insulating curtain used for the experiment was compared using the P, N, S, U and T company, which are commercially available, and the heat flux due to temperature difference between the experimental apparatus and the outside was compared and analyzed. When the internal temperature of the experimental result is the maximum temperature $60^{\circ}C$, the heat flux of multi-later insulating curtain is T Co.($73.1W/m^2$) > S Co.($119.5W/m^2$) > U Co.($155W/m^2$) > N Co.($163.1W/m^2$) > P Co.($177.7W/m^2$). The heat flux means the quantity of heat passing through the unit time per unit area, and the higher the numerical value, the higher the quantity of heat passing through the multi-layer insulating curtain. This can be determined that high heat fluxes produce low heat resistance. Further, it has been found that the weight of the insulating curtain is largely unrelated to the heat insulating property, and the heat insulating curtain having a thickness containing a high internal air layer is excellent in the heat insulating property. In the future when manufacturing a heat insulating curtain, It is judged that it is desirable to manufacture a combination of heat insulating materials that contain a high internal air layer content and that can maintain the air layer even for long-term use while minimizing the volume.

• 한국포장학회지
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• 제12권1호
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• pp.45-53
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• 2006

Thermal insulation is used in a variety of applications to protect temperature sensitive products from thermal damage. Several factors affect the performance of insulation packages. Among these factors, the thermal resistance of the insulating wall is the most important factor to determine the performance of the insulating package. In many cases, insulating wall consists of multi-layered structure and the heat transfer through this structure is a very complex process. In this study, an one-dimensional mathematical model, which includes all of the heat transfer principles covering conduction, convection and radiation in multi-layered structure, were developed. Based on this model, several heat transfer phenomena occurred in the air space between the layer of the insulating wall were investigated. From the simulation results, it was observed that the heat transfer through the air space between the layer were dominated by conduction and radiation and the low emissivity of the surface of each solid layer of the wall can dramatically increase the thermal resistance of the wall. For practical use, an equation was derived for the calculation of the thermal resistance of a multi-layered wall.

• 한국화재소방학회논문지
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• 제17권1호
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• pp.76-84
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• 2003

본 연구는 산업현장에서 단열재로 .사용되고 있는 폴리스티렌 폼, 폴리우레탄 폼, 폴리에틸렌 폼과 같은 플라스틱 단열재의 화재특성을 구명하고자 하였다. 플라스틱 단열재의 화재특성은 ISO 5660에 따라 콘칼로리미터 시험을 수행하였다. 사용된 실험재료는 국내에서 생산되는 상업용 플라스틱 단열재를 사용하였고 그들의 조성은 제조자에 의해 밝혀지지 않았다. 연구 결과플라스틱 단열재의 열방출율은 재료의 밀도와 열플럭스의 증가에 따라 증가하였다. 플라스틱 단열재 중 폴리에틸렌 폼이 최대열방출율 및 평균열방출율이 가장 크게 나타났고, 열플럭스 및 밀도의 증가에 따른 최대열방출율의 증가율도 가장 큰 것으로 나타났다. 플라스틱 단열재에 의한 화재예방을 위해 제품의 종류 및 열플럭스의 크기에 따른 열방출 평가 기준을 제시하였다.

• 대한안전경영과학회지
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• 제20권4호
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• pp.15-19
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• 2018

The purpose of this study is to enhance heat insulation effect and to decrease fire hazard by attaching aluminum foil to expanded polystyrene, which is mainly used for insulating materials, to have fire retardant. The result of the test confirmed that the insulating materials, expanded polystyrene of $10kg/m^3$ and $14kg/m^3$ of density attached aluminum foil on both sides, showed 12%, 14% of improved heat transfer coefficient respectively compared to existing expanded polystyrene of the same density. Besides, they met all the standards for the testing of heat release and gas hazard. On the other hand, the one made of general expanded polystyrene could not meet the standards of the heat release test and the gas hazard test.

• 전기학회논문지
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• 제61권4호
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• pp.580-584
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• 2012

The insulating oils perform a cooling and insulation action in electric power transformer. The mineral oil has immanent fire dangerousness and environmental contamination problem. Vegetable insulating oil has higher ignition point, flash point and more excellent biodegradability than conventional mineral oil. In a real oil-filled transformers, some of the power is dissipated in the form of heat. And transformer require the heat to be removed from the winding and insulator by forced convection of the insulating oil. The flow electrification occurs when insulating oil was forced to be circulated. In this paper, influence of temperature, velocity of flow, and insulating pipe and diameter on streaming electrification of vegetable insulating oil was investigated using forced circulation apparatus. Temperature effects were most significant, and it showed a peak in the temperature $30^{\circ}C$ to $35^{\circ}C$ at insulating and copper pipe. The change of flow electrification according to area variety could be checked by change of diameter.

• 공업화학
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• 제17권4호
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• pp.357-360
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• 2006

본 연구에서는 단열재로서의 페놀수지(PF) 발포폼의 물성과 응용가능성을 검토하였다. 실험결과 페놀수지 발포폼의 밀도는 $0.030g/cm^3$를 나타내었고, 열전도율은 $0.026kcal/m.h.^{\circ}C$를 나타내었다. 또한 페놀수지 발포폼은 $500^{\circ}C$로 1 h 동안 열을 가했을 경우 약 71.7 wt%가 휘발되었다. 그리고 페놀수지 발포폼의 화학구조는 단열재로서의 중요 물성인 closed cell 구조형태를 갖는 것으로 분석되었다. 따라서 제조된 페놀수지 발포폼은 단열소재로서의 우수한 물성을 갖는 것으로 확인되었다.

• 한국산학기술학회논문지
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• 제12권11호
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• pp.5188-5193
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• 2011

본 연구는 변압기 내부에 있는 절연유의 온도제어를 목적으로 열전소자인 펠티어 소자와 무전력 냉각장치인 Heat pipe를 이용한 다양한 시스템을 설계 제작하여, 절연유의 용량별 온도제어에 적용함으로써 최적의 시스템을 구현할 수 있었다. 실험을 통하여 $60^{\circ}C$ 이내의 상태에서는 Heat pipe 100 W + 펠티어 100 W의 조합형이 순수 Heat pipe 300 W보다 탁월한 성능을 확인할 수 있었다. 이를 통하여 조합형의 적정설계 방식이 우수하다는 것을 증명하고, 조합형을 사용함으로써 전기절약 효과와 수배전반의 보다 더 효율적인 관리에 기여하고자 한다.

• 설비공학논문집
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• 제21권12호
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• pp.656-662
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• 2009

In this paper, the heat resistance reliability of an axial smoke exhaust fan was investigated. An axial smoke exhaust fan should be capable of operating at $250^{\circ}C$ for 2 hours. The heat resistance reliability was evaluated by the heat resistance reliability test. A B10 life with a 90% confidence level was estimated to be about 48 minute. The failure occurred in the motor due to high temperature. The main failure mechanisms of the motor were melting of bond and insulating paper and burning of insulating materials in the coil. The heat resistance reliability was improved by changing the way to unite the core and the coil and by replacing the insulating paper and the insulating materials of the coil. A B10 life with a 90% confidence level of a modified axial smoke exhaust fan was estimated to be over 120 minute.

• 한국지반환경공학회 논문집
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• 제18권7호
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• pp.5-12
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• 2017

강원권의 동절기에는 한랭기후로 인한 복합적으로 터널 라이닝 표면이 열화되는 형태와 외관상의 문제 및 균열이 발생하게 된다. 이에 따른 재해복구 관련 기술 개발을 통한 복구비용의 절감이 필요한 실정이지만, 국내에서는 기온에 따른 도로터널 라이닝의 피해 저감에 대한 연구는 미비한 상태이다. 따라서, 본 논문에서는 터널 라이닝의 단열성능을 개선하기 위하여 단열재료(에어로젤, 액상단열재)에 열전달량 실험을 실시하였다. 실험결과 단열재의 도포에 따라 열전달량이 상당히 감소하는 것으로 나타나, 동결지역에서의 터널라이닝 피해저감 효과를 확인할 수 있었다.