• Journal of the Korean earth science society
• /
• v.30 no.1
• /
• pp.58-68
• /
• 2009

Three-dimensional distributions of longwave radiation flux for the April-September 1998 period are generated from radiative transfer calculations using the GEWEX Asian Monsoon Experiment (GAME) reanalysis temperature and humidity profiles and International Satellite Cloud Climatology Project (ISCCP) cloudiness as inputs to understand the effect of cloud radiative forcing in the monsoon season. By subtracting the heating of the clear atmosphere from the cloudy radiative heating, cloud-induced atmospheric radiative heating has been obtained. Emphasis is placed on the impact of horizontal gradients of the cloud-generated radiative heating on the Asian monsoon. Cloud-induced heating exhibits its maximum heating areas within the Indian Ocean and minimum heating over the Tibetan Plateau, which establishes the north-south oriented differential heating gradient. Considering that the differential heating is a ultimate source generating the atmospheric circulation, the cloud-induced heating gradient established between the Indian Ocean and the Plateau can enhance the strength of the north-south Hadley-type monsoon circulation. Cooling at cloud top and warming at cloud bottom, which are the vertical distributions of cloud-induced heating, can exert on the monsoon circulation by altering the atmospheric stability.

• 한국지구과학회:학술대회논문집
• /
• 2003.09a
• /
• pp.112-125
• /
• 2003

구름의 몬순의 활동에 있어서 직접적으로나 간접적으로 영향을 준다. 본 연구에서는 이러한 구름이 몬순의 활동에 어떠한 영향을 주는지를 알아보기 위해 ISCCP 구름자료와 GAME 재분석 자료를 입력자료로한 장파 복사 모델을 수행하였다. 모델 수행의 결과로 얻어진 대기 상부에서의 플럭스는 CERES 관측치와 비교하였으며, 구름에 의한 가열율은 몬순활동을 해석하기 위해 사용하였다. 구름이 몬순에 끼치는 영향을 파악하기 위해 맑은 대기의 가열율과 구름을 포함한 평균 대기의 가열율의 차이를 구하였으며, 이를 수평과 연직분포의 관점에서 해석하였다. 가열율의 지리적 분포는 수평적으로는 인도양에서 장파 복사 가열율의 최대가 나타났으며, 가열의 최저 (냉각)은 티벳고원에 나타났다. 이러한 공간적 분포는 구름이 남북방향으로 차등가열을 유발시키고 있음을 보여주고 있어 구름의 분포가 열적인 몬순순환을 강화시켜주고 있음을 시사하고 있다. 이러한 차등가열의 강화는 동서방향으로도 나타나 구름이 동서방향 순환에도 영향을 줄 수 있음을 보여준다. 구름에 의한 복사 가열의 연직구조는 운정에 의한 냉각과 운저에 의한 가열이 일어날 수 있음을 보여주고 있으며, 이로 인해 대기의 불안정성이 높아져 연직 운동을 향상시킬 수 있는 역할을 하고 있음이 밝혀졌다. 즉 몬순순환에 의해 생성된 구름은 구름 생성의 원인이 되었던 순환을 더욱 강화시키고 있음을 보이고 있다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1993.05a
• /
• pp.112-115
• /
• 1993

복사관을 이용한 가열방식은 복사관내에서 연료를 연소시킬 때 얻어지는 열이 관을 통하여 복사됨으로서 피가열물을 가열하는 방식으로서 분위기제어가 필요한 열처리로 등에 널리 사용되고 있다. 본 연구에서는 연속 소둔설비용으로서 저 NOx화 및 복사관의 표면온도를 상대적으로 균일하게 가열시키는 특성을 가진 버너의 개발을 위한 것으로서 실기규모 연소실험을 수행하였다. 연소실험은 기존버너 및 편심노즐버너에 대해서 수행하였으며 특히 개발실험용 버너의 실험과정에서는 새로 고안된 버너의 성능평가로부터 최적화에 이르기까지의 종합적인 실험을 수행하였다. 개발실험에 의해 편심노즐을 특징으로 하는 2단연소식 복사관버너를 고안하였으며 시제품버너의 성능실험결과 기존버너보다 NOx방출량에서 30%의 감소를 보여주었으며 복사관에서의 온도의 균일성이 향상되었음을 확인하였다.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.9 no.3
• /
• pp.85-91
• /
• 2005

Radiative heating of a liquid rocket base plane due to plume emission is numerically investigated. Calculation of flow and temperature fields around rocket nozzle precedes and thereby realistic plume shape and temperature distribution inside the plume are obtained. Based on the calculated temperature field, radiative transfer equation is solved by discrete ordinate method. With the sample rocket plume, the averaged radiative heat flux reaching the base plane is calculated about 5 kw/m$^{2}$ at the flight altitude of 10.9 km. This value is small compared with radiative heat flux caused by constant-temperature (1500 K) plume emission, but it is not negligibly small. At higher. altitude (29.8km), view factor between the base plane and the exhaust plume is increased due to the increased expansion angle of the plume. Nevertheless, the radiative heating disappears since the base plane is heated to high temperature (above 1000 K due to convective heat transfer.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.9
• /
• pp.737-744
• /
• 2012

The finite volume method for radiation is applied for the analysis of radiative base heating by SE and PE of the aircraft exhaust plume. The exhaust plume is considered as an absorbing, emitting, and scattering medium, while the base plane is assumed to be cold and black. The radiative properties of non-gray gases are obtained through the WSGGM, and the particle is modelled as spheres. The present method is validated by comparing the results with those of the backward Monte-Carlo method and then the radiative base heating characteristics are analyzed by changing such various parameters as particle concentration, temperature, and scattering phase function. The results show that the radiative heat flux coming into the base plane decreases with altitude and distance, but it increases as the particle temperature increases. The forward scattering of particles increases PE while it decreases SE.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.8
• /
• pp.553-561
• /
• 2017

The main motivation for this study was to establish a CFD-based procedure for the analysis of heating characteristics, particularly in industrial furnaces. As certain open-source software packages have gained popularity in dealing with complex industrial problems, the OpenFOAM framework was selected for further development of advanced physical models to meet industrial requirements. In this study, the newly developed comprehensive model was applied to simulate physical processes in the full-scale horizontal furnace of a continuous galvanizing line (CGL). The numerical results obtained indicate that the current approach predicts heating characteristics reasonably well. It was also found that radiative heat transfer plays a dominant role in heating the moving strip. To improve the predictability of our method, further work is required to model the turbulence-chemistry interaction realistically, as well as to impose a physically correct thermal wall boundary condition.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.10 no.3
• /
• pp.408-418
• /
• 1986

본 연구에서는 표면은 단단하고 내면은 강인한 조직을 얻기위하여 대형 성형 탄 로울에 대하여 노에서의 급속가열 및 대기 상태에서의 자연냉각의 열처리가 수행 되어진다. 급속가열 및 냉각시 성형탄 로울 내부의 온도 분포 예측을 위하여 대류 및 복사 열전달 경계조건을 가지는 1차원 비정상 열전도 방정식이 유한 차분법을 사 용하여 해석되어졌다. 여기서 급속가열시 연소가스로 부터 기체복사에 의하여 성 형탄 로울의 바깥표면을 통하여 흡수되는 열량은

• Applied Chemistry for Engineering
• /
• v.2 no.4
• /
• pp.393-398
• /
• 1991

An experimental reactor system was devised and employed to examine catalytic coal gasification. A 4-kw tungsten halogen lamp heater combinded with a graphite sample basket coated with silicon nitride film made rapid heating and cooling possible. Also a small graphite cap on the thermocouple tip which located just beneath the sample basket helped remarkably to read real temperatures. Silicon nitride film on the basket and the cap showed very good protection against the reaction between graphite and oxidant gases during the experiments. The weight of specimen could be continuously measured without disturbance.

• Atmosphere
• /
• v.23 no.1
• /
• pp.85-92
• /
• 2013

We estimate atmospheric radiative heating effect of aerosols, based on AErosol RObotic NETwork (AERONET) and lidar observations and radiative transfer calculations. The column radiation model (CRM) is modified to ingest the AERONET measured variables (aerosol optical depth, single scattering albedo, and asymmetric parameter) and subsequently calculate the optical parameters at the 19 bands from the data obtained at four wavelengths. The aerosol radiative forcing at the surface and the top of the atmosphere, and atmospheric absorption on pollution (April 15, 2001) and dust (April 17~18, 2001) days are 3~4 times greater than those on clear-sky days (April 14 and 16, 2001). The atmospheric radiative heating rate (${\Delta}H$) and heating rate by aerosols (${\Delta}H_{aerosol}$) are estimated to be about $3\;K\;day^{-1}$ and $1{\sim}3\;K\;day^{-1}$ for pollution and dust aerosol layers. The sensitivity test showed that a 10% uncertainty in the single scattering albedo results in 30% uncertainties in aerosol radiative forcing at the surface and at the top of the atmosphere and 60% uncertainties in atmospheric forcing, thereby translated to about 35% uncertainties in ${\Delta}H$. This result suggests that atmospheric radiative heating is largely determined by the amount of light-absorbing aerosols.

• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 1997.11a
• /
• pp.217-222
• /
• 1997

본 연구에서는 국내에서 원심주조로 제작되어 소둔로내에서 사용되는 복사전열 튜브의 손상 및 균열발생 기구(mechanism)를 조사한 후, 파손된 튜브 샘플의 균열주위를 금속학적으로 관찰하고, 관찰결과 및 재료의 성분분석 결과를 분석하여, 튜브의 파손원인을 분석함으로써, 향후 균열발생을 방지할 수 있는 대책에 대해 연구하였다. 우선 복사전열 튜브의 내면 균열발생 부위에 대해 현미경 관찰을 실시하였으며, 균열부의 산화물 및 균열부근 튜브모재에 대해서 성분분석을 실시하고, 전자현미경(SEM, Scanning Electron Microscope)으로 균열을 상세히 관찰하여 그 결과로부터 파손원인을 규명하였다. (중략)