• Proceedings of the Korean Vacuum Society Conference
• /
• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
• /
• pp.69.1-69.1
• /
• 2015

우주환경은 고진공 환경과 태양 복사열에 의한 고온 환경 및 극저온이 반복되는 가혹한 환경으로 특징지어지는데, 위성체는 지상에서 발사되어 우주궤도에 진입한 순간부터는 계속해서 우주환경에 노출된다. 위성체가 이러한 가혹한 우주환경에 노출될 경우 주요부품에 기능장애가 초래되기도 하며 이는 결국 임무의 실패로 이어지도 한다. 따라서 위성체는 지상에서 우주환경시험을 거쳐 기능 및 작동상태를 점검해야 하며, 이를 위해서는 우주환경을 모사 할 수 있는 우주환경 모사장비가 필요하다. 우주환경모사장비라함은 우주환경의 주특징인 고진공상태와 극저온 및 고온 환경을 모사할 수 있는 지상장비를 말하며, 통상 열진공챔버라고 불린다. 한국항공우주연구원에서는 위성의 부품레벨에서부터 대형위성시스템의 열진공시험 수행을 위한 다양한 진공챔버를 보유하고 있으며, 그 직경이 0.7 m인 소형에서부터 직경 9 m, 길이 10 m급의 대형열진공챔버에 이른다. 대형 챔버의 경우 고기능화에 따라 대형화 되어 가는 위성의 국산화 개발을 위하여 순수 국내 기술로 제작된 우주환경모사용 챔버이다. 본 대형열진공챔버의 제작 및 유지 현황에 대해 논의한다.

• Transactions of the Korean Society of Mechanical Engineers
• /
• 제15권3호
• /
• pp.1021-1029
• /
• 1991

본 연구에서는 2차원 정사각형 밀폐공간내에서 흡수 및 방사하는 회기체에 대 한 자연대류-복사 열전달을 P-1 및 P-3 근사법을 이용하고 수치해석을 통하여 유동 및 열전달 특성을 연구하였고 Plank 수, 광학두께 및 벽방사율의 영향을 조사하였다. 또한 P-3 근사해와 비교함으로써 P-1 근사해의 적용범위를 고찰하였다.

• Congress of the korean instutite of fire investigation
• /
• 한국화재조사학회 2011년도 제21회 춘계학술대회
• /
• pp.127-129
• /
• 2011

• Fire Science and Engineering
• /
• 제22권5호
• /
• pp.72-78
• /
• 2008

The mass loss rate and heat release rate of EPS sandwich panel cores were analysed using variable external irradiation level. The experimental materials were exposed to incident heat fluxes form 20 to 50 kW/$m^2$. For the measurement of mass loss rate and heat release rate, the size of specimen was $100mm{\times}100mm{\times}50mm$ and the samples were 3 different kinds. The combustion heat were carried out from the Oxygen bomb calorimeter and the mass loss rate and heat release rate were carried out from the Mass loss calorimeter according to ISO 5660-1. As the results of this study, the mass loss rate of Type A, B, and C were 2.7 g/$m^2s$, 2.8 g/$m^2s$, and 2.3 g/$m^2s$ and the heat release rate of Type A, B, and C were 58.23 kW/$m^2$, 47.19 kW/$m^2$, and 50.06 kW/$m^2$ respectively at the heat flux of 50 kW/$m^2$. In conclusion, when the heat release characteristics applied to a classification system of Canada, Type A and C can be classified grade C-3, and Type C can be classified grade C-2 from all data of this study.

• Journal of the Korean Society of Clothing and Textiles
• /
• 제23권6호
• /
• pp.853-863
• /
• 1999

the change of physical properties (thickness, weight, air permeability) and mechanical properties(abrasion resistance breaking load and displacement) of samples were determined after heat exposure by a RPP tester. The effect of exposure time and heat flux intensity on the changes and the relationship between physical properties and mechanical properties were investigated. FR treated cotton Kevlar/PBI and Nomex with different structureal characteristics were chosen for specimens. The changes of physical properties and mechanical properties were calculated based on their initial values before heat exposure. The longer exposure time and the high heat flux intensity the more changes of those properties. Heat flux intensity was more effective on the changes, The showed to be affected by an interplay of shrinkage and pyrolysis products loss. The changes of thickness and abrasion resistance showed to be higher for plain weave fabric and those of air permeabiliyt and breaking load and displacement for twill weave fabric. While FR treated cotton which have high RPP value experienced serious and detrimental changes after heat exposure Kevlar/PBI which has low RPP value showed no high changes. In conclusion it could be confirmed that when total performance of a protective clothing is estimated retention capability of physical and mechanical properties after heat exposure as well as RPP value must be considered.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• 제20권8호
• /
• pp.2681-2692
• /
• 1996

The finite-volume method for radiation in a three-dimensional non-orthogonal gas turbine combustion chamber with absorbing, emitting and anisotropically scattering medium is presented. The governing radiative transfer equation and its discretization equation using the step scheme are examined, while geometric relations which transform the Cartesian coordinate to a general body-fitted coordinate are provided to close the finite-volume formulation. The scattering phase function is modeled by a Legendre polynomial series. After a benchmark solution for three-dimensional rectangular combustor is obtained to validate the present formulation, a problem in three-dimensional non-orthogonal gas turbine combustor is investigated by changing such parameters as scattering albedo, scattering phase function and optical thickness. Heat flux in case of isotropic scattering is the same as that of non-scattering with specified heat generation in the medium. Forward scattering is found to produce higher radiative heat flux at hot and cold wall than backward scattering and optical thickness is also shown to play an important role in the problem. Results show that finite-volume method for radiation works well in orthogonal and non-orthogonal systems.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• 제35권5호
• /
• pp.467-472
• /
• 2011

The heat transfer over a radial heat sink, adapted for LED (light emitting diode) downlights, was experimentally and analytically investigated. We added radiation heat transfer into a previous calculation that neglected this factor. The numerical results agreed well with experimental results. Parametric studies were performed to compare the effects of the geometric parameters (fin length, fin height, ideal number of fins) and the operating parameter (heat flux) on the average heat-sink temperature from the heat-sink array. We found the fin length that maximizes the heattransfer performance. As the emissivity increased, the effect of geometric parameters on the radiation heat transfer decreased.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 한국정보통신학회 2015년도 춘계학술대회
• /
• pp.326-328
• /
• 2015

Function of the window of the building is an environment of the room through the entry of solar radiation. It is vulnerable to significant energy conservation off the thermal efficiency. Also this summer, cooling costs are weighted because of excessive solar radiation. In this paper, we develop a windows automatic control system to use the indoor environmental information, such as home temperature, humidity, light intensity, solar radiation. The system collects the indoor environment information using a variety of sensor, using the collected information, and controls the motor to the system to control the window.

• Proceedings of the Korean Society of Dyers and Finishers Conference
• /
• 한국염색가공학회 2011년도 제45차 학술발표회
• /
• pp.15-15
• /
• 2011

본 연구는 기존의 하우스 랩이 가지는 방풍, 방수 기능 외에 복사열 차단성, 열반사성, 통기성, 투습성, 난연성, 방수성 및 단열성 등의 다기능성이 발현되는 우수한 건축용 하우스 랩을 제조하는 목적으로 시스-코어 섬유로 이루어진 부직포층, 통기성 합성수지 필름층, 니들펀칭 복합 부직포층 및 고분자 필름이 일면 또는 양면에 코팅된 내식성 알루미늄 필름층이 순차적으로 적층되고 핫-멜트 라미네이팅에 의하여 합지 된 다기능성 하우스 랩 및 그의 따른 제조방법에 관한 것이다. 상기 니들펀칭 부직포 내부에 포함 된 아라미드 섬유에 의해 우수한 난연효과를 가지며, 통기성 필름에 의하여 투습방수 기능을 가질 수 있으며, 니들펀칭 부직포층에 다량의 공기가 함유되어 보온성이 우수하고, 내식성 알루미늄 필름층이 가진 빛에 대해 우수한 방사성으로 복사열을 차단하여 단열효과를 나타내는 하우스 랩을 제조하였다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• 제18권4호
• /
• pp.287-296
• /
• 2006

In this paper, optimal control strategy of the air-conditioning system with slab thermal storage was investigated based on the optimal control theory. An optimal heat output to the plenum chamber and the air-conditioned room was determined based on two kinds of criterion functions. The first one requires small deviation in room air temperature from a set-point value and low energy consumption. It is shown that the optimized control is to store heat through the whole storage time and to increase storage rate gradually with time. As the second case, a criterion that both a deviation of operative temperature from a set-point temperature and the energy consumption should be minimized was adopted. The room air temperature was a little high and the cooling load during storage time was reduced, compared with the results when a criterion function considering only the room air temperature is used.