• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.34.1-34.1
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• 2011

태양전지 모듈의 25년 이상 보증을 위해 태양전지 모듈을 구성하는 부품 소재의 장기 열화메카니즘 연구가 중요시되고 있다. 그 중 봉지제(Encapsulation) 부품으로 적용되고 있는 태양전지 모듈용 에틸렌 비닐 아세테이트(Ethylene Vinyl Acetate, EVA)는 셀을 보호하는 폴리머 부품으로 장기 열화특성 연구가 중요하다. 따라서 EVA를 가속열화하여 25년 보증 내구성을 보유하고 있는지 연구가 필요하다. 본 연구에서는 태양전지 모듈을 구성하는 재료 중 외부환경에 민감한 폴리머 소재인 EVA의 Ultraviolet (UV), 온도 두 환경스트레스 조건을 적용한 가속수명시험을 수행하고 장기 열화메카니즘을 분석하였다. 시험에 앞서 UV/온도 가속수명시험을 설계하였다. UV/온도 가속조건을 설정하기 위해 실환경에서 변화하는 UV와 온도를 일정한 값으로 나타낼 수 있는 유효 UV (Effective UV)와 유효 온도(Effective temperature)를 도출하였다. 이를 통해 UV/온도 가속조건을 설정하였고 1년 및 25년 동안 EVA에 인가되는 stress와 동일한 양을 인가할 수 있는 시험시간을 결정하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.100.1-100.1
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• 2012

태양전지 모듈의 25년 이상 장기간 정상 발전을 위해 태양전지 모듈을 구성하는 부품 소재의 장기 열화메커니즘 연구가 중요시되고 있다. 결정질 및 박막 태양전지 모듈 내 셀을 보호하기 위한 봉지재(Encapsulation)로 다양한 폴리머 재료가 적용되고 있다. 봉지재 부품으로 적용되고 있는 에틸렌 비닐 아세테이트(Ethylene Vinyl Acetate, EVA)는 장기 열화특성 및 내구성 개선 연구가 중요하다. 따라서 EVA를 가속열화하여 열화메커니즘 분석과 25년 보증 내구성을 보유하고 있는지 연구가 필요하다. 본 연구에서는 EVA의 Ultraviolet(UV), 온도 복합 환경스트레스 조건을 적용한 가속시험을 수행하고 장기 열화메커니즘을 분석하였다. 수명 및 손상모델을 이용하여 실환경에서 변화하는 UV와 온도를 일정한 값으로 나타낼 수 있는 UV/온도 가속조건을 설계하였다. 이를 통해 UV/온도 가속조건을 설정하였고 1년 및 25년 동안 EVA에 인가되는 stress와 유사한 양을 인가할 수 있는 시험시간을 결정하였다. 시험 후 전자현미경, AFM, FT-IR, TGA, DSC 등의 분석을 통해 열화메커니즘을 도출하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.386-391
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• 1998

국내 가압경수로 가압기 안전밸브는 운영기술지침서에 따라 운전 중과 같은 환경조건에서 압력설정치(2,485 psig) 시험을 수행하도록 규정되어 있다. 가압기 안전 밸브는 일정한 주기로 압력설정치 시험이 수행되고 있으나, 시험시의 주변 온도, 사용 유체 등 그 시험 조건에 따라 압력설정 허용치 $\pm$1% 이상의 편차가 발생할 수 있음이 확인되고 있다. 본 연구에서는 압력설정치 시험시의 주변온도 상태에 따른 설정치 변동 사례를 조사하고, 보수 후 압력설정치 조정을 위한 대체 방안과 그 문제점을 고찰하였다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.203-208
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• 2016

In this study, to clarify the differences rebar corrosion beginning, through the actual corrosion accelerated test in corrosion time and laboratory test chamber of the structure of the marine environment results in both environments, it is an object of correlation coefficient derived. The accelerated corrosion test was carried out by two case, I.e., one is $20^{\circ}C$ of low temperaure codition(case 1), and the other is $65^{\circ}C$ of high temperaute codition(case 2). Whether corroions occurs, it was measures using half-cell potential method. The results indicated that case 2 is to acclerate the corrosion of rebar about 1.7~1.8 times as compared with case 1, thenthe corrosion of rebar embadded in concrete occurred according to the order of OPC60, FA, BS, OPC35. Correlation coefficient between acclerated corrosion test and long-term exposure test, case 1 is 2.45 to 2.94, and case 2 is 4.37~4.99.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.5
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• pp.466-473
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• 2011

The purpose of satellite thermal control design is to maintain all the elements of a spacecraft system within their temperature limits for all mission phases. The thermal analysis model for Low Earth Orbit satellite payload level simulation is established by considering thermal vacuum test environment condition, thermal vacuum chamber configuration, and satellite's payload inner thermal environment. The established thermal analysis model is used to determine thermal vacuum test conditions and test case requirements.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.259-261
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• 2012

The effect of high-temperature on the flexural modulus of epoxy resin were evaluated using universal testing machine with 3-point bending and dynamic mechanical analyzer. Temperatures of $30^{\circ}C$, $100^{\circ}C$, and $140^{\circ}C$ were considered for flexural test. The specimens having aspect ratio of 16, 32, and 40 were used. The results of storage modulus from DMA were similar to those from flexural test along with given temperatures. It is found that the flexural modulus increased with increasing aspect ratio and the specimen having aspect ratio of above 32 would be suitable for the evaluation of composite material properties under high temperature condition.

• Electronics and Telecommunications Trends
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• v.12 no.6 s.48
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• pp.131-135
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• 1997

본 고는 ATM교환기 고온 상태 동작 특성을 시험하기 위하여 온도 조건, 시험 시간, 시험 절차, 시험 방법, 세부 기준, 판정 기준 등을 정한 것으로, 고온 동작 기준은 한국통신 환경 관리기준 및 품질 표준서-4101을 근거로 하였다. 온도 조건은 평균 $49^{\circ}C$를 유지하되 허용편차는 $1^{\circ}C$내외로 시험되어야 하며, 시험 시간은 온도 상승 및 하강 시간과 장애 발생시 고장 조치 시간 등을 포함하여 최대 72시간을 넘지 않아야 하고, 고온 유지시간은 48시간으로 채택한, ATM 교환기 고온 시험 방법과 기준을 제시하였다.

• Journal of Aerospace System Engineering
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• v.13 no.3
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• pp.87-94
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• 2019

In this paper, we test procedures to demonstrate operating environmental conditions that can be exposed to UAV during its life-cycle are proposed. They are set up to be used in a large-sized climate chamber, one of the facilities of the Agency for Defense Development corresponding with the system requirements. The test steps and profile details were more specifically suggested for rainfall, humidity, and temperature (low-temperature storage and operation, high-temperature operation and solar radiation), and MIL-STD-810G w/Change-1-based.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.283-288
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• 2018

Since the crack self-healing materials are activated according to the exposure environmental conditions from the time of crack occurrence, it is very important to clarify the relationship between the healing performance and the exposure environmental conditions of the crack surface. In this paper, the influence of the exposure environmental conditions on the crack healing performance of self-healing repair mortar was investigated through the water permeability test. The influence of temperature and humidity on the crack width of cracked specimens was evaluated. As a result of measuring the change of the crack width, the effect of curing temperature was negligible but it was confirmed that crack-closing occurred due to the change of dry-wet condition. The healing materials produced on the crack surface of the specimens was identified as calcite minerals. Since the minerals with high density are precipitated under the influence of gravity, the healing performance is somewhat different according to the direction of the crack surface, and the healing performance was significantly improved in the wet exposure condition than the air exposure condition.

• Journal of the Korean GEO-environmental Society
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• v.13 no.11
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• pp.51-60
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• 2012

In order to characterize the shear strength of the frozen sand for foundation design in cold region and prediction of adfreeze bond strength, many researchers developed test techniques and carried out many tests to analyze shear strength properties of the frozen sand for half a century. However, many studies for shear strength properties of the frozen sand have been carried out with limited circumstances, even though shear strength of the froze sand can be affected by various influence factors such as soil type, temperature conditions, and magnitude of normal stress. In this study, direct shear test equipment was used to analyze the shear strength characteristics of the frozen sand. Direct shear test equipment was designed for cold weather, and the direct shear tests were carried out inside of large-scaled low temperature chamber. Three soil types-two uniform sands and one well graded soil were used to analyze the shear strength of the frozen sand with three different temperature conditions and three different vertical confining pressures. In this research, a series of direct shear tests for shear strength of the frozen sand have been conducted to demonstrate the efficiency of effectiveness of the test equipment and low temperature chamber. This research also showed that shear strength of the froze sand increased with decreasing temperature condition, but the influence of vertical confining pressure was insignificant to the shear strength of the frozen sand.