• 대한원격탐사학회지
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• 제29권2호
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• pp.197-207
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• 2013

복사율 및 대기효과는 대상지표의 온도 추정에 오차를 발생시키는 주요 원인이 된다. 일반적인 경우, 대상지표에 대한 정확한 복사율 정보를 알 수 없으므로, 단일밴드로 이루어진 열적외선영상으로부터 대상지표의 정확한 온도를 추정하는 것은 매우 어렵다. 따라서, 본 연구에서는 대상지표의 온도를 추정하기보다는 Landsat 위성영상을 이용한 지표 간 지표온도차 추정기법을 제안하고자 한다. 연구를 위하여 대기효과가 전체영상에 동일하게 적용된다고 가정하였다. 수분량 및 온도의 오차로부터 제안된 기법에 대한 오차분석을 수행하였다. 오차분석 결과, 수분량의 오차범위가 ${\pm}0.302g/cm^2$일 때, 제안된 기법의 오차는 복사휘도차이가 0.2, 0.5 및 $1.0Wm^{-2}sr^{-1}{\mu}m$일 때 각각 약 ${\pm}0.06K$, ${\pm}0.15K$, ${\pm}0.30K$임을 보였다. 또한, 온도의 오차가 ${\pm}2.41K$일 때, 온도차의 오차범위는 복사휘도차이가 0.2, 0.5 및 $1.0Wm^{-2}sr^{-1}{\mu}m$일 때 각각 약 ${\pm}0.037K$, ${\pm}0.089K$, ${\pm}0.168K$이고, 온도의 오차가 ${\pm}0.56K$일 때에는 약 ${\pm}0.008K$, ${\pm}0.020K$, ${\pm}0.038K$의 오차가 있음을 보였다. 이는 제안된 기법이 높은 정밀도로 지표 간 지표온도차를 추정할 수 있음을 의미한다.

• 항공우주기술
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• 제12권1호
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• pp.40-45
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• 2013

적외선 영상을 획득하는 인공위성의 적외선 검출기는 임무 궤도에서 정확한 성능을 보장받기 위해 발사 전 지상에서 흑체를 이용한 검보정 환경시험을 거쳐야 한다. 적외선 탑 재체의 검보정 기준이 되는 대구경흑체는 궤도환경 지상시험을 위해 진공환경에 적합한 재질로 구성되어야 하며, $-40^{\circ}C$에서 $+40^{\circ}C$까지의 온도 범위에서 중심 80 %의 영역에 대해 $2^{\circ}C$ 이하의 표면 온도 균일도와 0.95 이상의 방사율을 가져야 한다. 열유동해석 결과로 도출된 대구경흑체는 $1m{\times}1m{\times}8mm$의 크기의 구리판에 방사율을 높이기 위한 알루미늄 하니콤 코아를 부착하고, 블랙페인트를 도포하여 제작되었으며, 온도 조절을 위해 뒷면에는 질소가스 흐름을 위한 구리튜브가 용접되었다. 한국항공우주연구원의 광학열 진공챔버에서 수행된 대구경흑체 검증시험에서 20개의 저항온도센서와 적외선카메라를 이용하여 표면 온도 분포를 측정하여 ${\pm}40^{\circ}C$의 온도 범위에서 약 $1^{\circ}C$의 온도 균일도를 가짐을 확인하였다. 표면방사율은 대기압, $40^{\circ}C$에서 0.975로 측정되었다.

• 생물환경조절학회지
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• 제28권4호
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• pp.311-321
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• 2019

온실에서 겨울철 야간에는 열손실을 줄이기 위한 목적으로, 여름철 주간에는 차광을 위한 목적으로 스크린을 사용하고 있다. 온실의 냉난방 에너지 절감효과에 큰 영향을 미치는 스크린의 장파복사 방사율과 흡수율은 온실에 설치할 적절한 스크린을 선택하는데 있어서 중요한 요소가 되며 이러한 특성값들을 정확하게 측정할 수 있는 방법이 필요하다. 외부 환경조건에서 스크린의 장파복사 특성의 측정과 관련된 연구가 일부 수행된 바 있지만 모든 종류의 스크린에 적용할 수 있는 방법은 아니고 공극이 있는 스크린 자재에만 적용이 가능한 방법이다. 본 연구에서는 순복사계 및 야간복사계를 사용하여 온실 스크린의 장파복사 흡수량과 방사량을 측정하고, 방사율, 흡수율 및 투과율을 결정하는 새로운 방법을 제시하였다. 특성값의 측정은 공극이 0인 4가지 종류의 스크린 자재에 대하여 수행하였다. 모든 자재가 장파복사 방사량이 흡수량보다 높게 나타났다. PE, LD-13, LD-15 and PH-2의 장파복사 방사율은 각각 $0.439{\pm}0.020$, $0.460{\pm}0.010$, $0.454{\pm}0.004$, and $0.499{\pm}0.006$ 범위로 나타났다.

• 한국표면공학회지
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• 제52권2호
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• pp.58-61
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• 2019

The aim of this study is to quantitatively demonstrate the possibility of heat transfer by thermal radiation by comparing heat transfer by conventional heat transfer and radiation by radiation. 1) The heat transfer was measured by using filler of TIM material with low thermal conductivity (CuS). As a result, heat transfer was easier than ceramic with high thermal conductivity ($Al_2O_3$ and $Si_3N_4$). 2) The reason for this is thought to be that the infrared wave due to radiation of the air diaphragm has moved easily. 3) From the above results, the heat dissipation of the TIM material indicates the possibility of heat transfer by thermal radiation.

• 천문학회지
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• 제29권spc1호
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• pp.169-170
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• 1996

In the past, it. was very difficult to distinguish thermal and non-thermal emission. Broadbent et a1. (1989) has developed a new technique with the help of the IRAS 60 micron emission. The distribution of non-thermal or synchrotron emission in the Galactic disk has been modeled from the 408 MHz all sky survey of Haslam et a1. (1982) after removal of the thermal component.. At. 408 MHz, t.here is very little absorption in the interstellar medium and the distribution along the line-of-sight. is inferred mainly from its presumed relationship to other tracers of spiral structure via a. number of fitted parameters. But. at lower frequencies, free-free absorption becomes important and can give some direct. information on the line of sight. distribution. We have modeled the thermal electron density according to the spiral arm models and the distribution of ionized hydrogen in the Galactic plane by Lockman (1976) and Cersosimo et. al. (1989) and have made predictions to compare with the surveys of Dwarakanath et al. (1990) at. 34.5 MHz and .Jones and Finlay (1974) at 29.9 MHz. The result confirms that the absorption model of the synchrotron emissivity in the Galactic plane is broadly corrected and illustrates the potential of the absorption technique.

• 한국군사과학기술학회지
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• 제22권5호
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• pp.644-653
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• 2019

With the development of themal observatory device(TOD), thermal camouflage system has been applied not only to the weapon system but also to the combat suit for soldiers. In this paper, the characteristic of thermal radiation of human body depending on the clothing material properties was analyzed through numerical simulations. The bioheat equation with thermoregulatory model was solved to obtain the realistic surface temperature of human body and these results are combined with the emissivity of human skin and clothing in order to calculate the thermal signature from the human body. According to each thermal resistance of clothing, the optimal background radiance which makes contrast radiance intensity(CRI) be lowest is different. Also, the average CRI variation per thermal resistance change is about twice as much as the case of evaporative resistance change.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1457-1459
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• 2003

This study reports the surface temperature pattern of the Tokyo Metropolitan area using the ASTER surface temperature product. The product is an image processed by applying temperature-emissivity separation to atmospheric corrected infrared thermal radiance of the land surface, then converted to surface temperature by using Planck's function. Daytime and nighttime observation in a cold season and a warm season were used in this study. As a result, 1) contrast between urban and suburban, 2) extraction of heating area in urban, 3) measurement of cooling effect of green space were achieved.

• 천문학회지
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• 제36권1호
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• pp.21-31
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• 2003

ASTRO-F /FIS will carry out all sky survey in the wavelength from 50 to 200 ${\mu}m$. At far infrared, stars and galaxies may not be good calibration sources because the IR fluxes could be sensitive to the dust shell of stars and star formation activities of galaxies. On the other hand, asteroids could be good calibration sources at far infrared because of rather simple spectral energy distribution. Recent progresses in thermal models for asteroids enable us to calculate the far infrared flux fairly accurately. We have derived the Bond albedos and diameters for 559 asteroids based on the IRAS and ground based optical data. Using these thermal parameters and standard thermal model, we have calculated the spectral energy distributions of asteroids from 10 to 200 ${\mu}m$. We have found that more than $70\%$ of our sample asteroids have flux errors less than $10\%$ within the context of the best fitting thermal models. In order to assess flux uncertainties due to model parameters, we have computed SEDs by varing external parameters such as emissivity, beaming parameter and phase integral. We have found that about 100 asteroids can be modeled to be better than $5.8\%$ of flux uncertainties. The systematic effects due to uncertainties in phase integral are not so important.

• 방사성폐기물학회지
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• 제21권3호
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• pp.359-370
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• 2023

The thermal integrity of spent nuclear fuels has to be maintained during their long-term dry storage. The detailed temperature distributions of spent fuel assemblies are essential for evaluating the integrity of their dry storage systems. In this study, a subchannel analysis model was developed for a canister of a single fuel assembly using the COBRA-SFS code. The thermal parameters affecting the peak cladding temperature (PCT) of the spent fuel assembly were identified, and sensitivity analyses were performed based on these parameters. The subchannel analysis results indicated the presence of a recirculation flow, based on natural convection, between the fuel assembly and downcomer region. The sensitivity analysis of the thermal parameters indicated that the PCT was affected by the emissivity of the fuel cladding and basket, convective heat transfer coefficient, and thermal conductivity of the fluid. However, the effects of the wall friction factor of the canister, form loss coefficient of the grid spacers, and thermal conductivities of the solid materials, on the PCT were predominantly ignored.

• 천문학회보
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• 제42권1호
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• pp.55.3-55.3
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• 2017

The L1641 cloud in Orion is an active site of star formation. We mapped a square region of 60 arcmin by 60 arcmin in the continuum emission from 0.89 mm to 2.0 mm wavelength using MUSIC mounted on the Caltech Submillimeter Observatory 10.4 m telescope. Eight sources were detected in at least two wavelength bands, and all the detected emission comes from thermal dust continuum radiation of dense cloud cores. Their spectral energy distributions were characterized. The dust emissivity spectral index is beta = 1.3 on average, within the range of typical cores in nearby star-forming regions. Two cores, V380 Ori NE and HH 34 MMS, have unusually low emissivity index of beta = 0.3. These cores may contain millimeter-sized dust grains, which suggests that the lifetime of some dense cores can be much longer than the free-fall timescale.