• 한국태양에너지학회 논문집
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• 제36권3호
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• pp.33-43
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• 2016

Daylight is an important factor which influences building energy efficiency and visual comfort for occupants. It is important to predict precise sky luminance at the early stages of design to reduce light energy in the building. This study predicted sky luminance distributions of standard sky model(CIE overcast sky, CIE clear sky) that was provided from the CIE(Commission internationale de $l^{\prime}{\acute{e}}clairage$). Afterward, result of sky luminance was compared and verified with simulation value of Radiance program. From the CIE overcast sky, zenith and horizon ratio is about 3:1. From the CIE clear sky, luminance value gets most high value around the sun. On the other hand, luminance value is the lowest in the opposite direction of the sun when angle is $90^{\circ}$ between the sun and sky element. As a result of comparing the calculation results with Radiance program, sky luminance prediction error rate is 0.4~1.3% when it is CIE overcast sky. Also, sky luminance prediction error rate is 0.3~1.5% when it is CIE clear sky. When compared with the results of radiance simulation, it was evaluated as fairly accurate.

• KIEAE Journal
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• 제12권2호
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• pp.25-32
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• 2012

This paper focused on the daylighting performance of residential high-rise buildings in South-Korea. the purpose of this study is to estimate the visual environment of sunlight coming into opening according to sky conditions, orientation of windows and each space of Apartment buildings. Season of the year, weather, and time of day combine with predictable movement patterns of the sun to create highly variable and dynamic daylighting conditions. Daylighting design is usually based on the dominant sky condition and the micro-climate for the building site. There are three common sky conditions: clear sky, overcast sky, and partly cloudy sky. The clear sky includes sunshine and is intense and brighter at the horizon than at the zenith, except in the area around the sun. Daylight received within a building is directly dependent upon the sun's position and the atmospheric conditions. Easily used charts, diagrams, and software programs allow study of solar geometry for any geographic location and time of day. on the other hand, the overcast sky is characterized by diffuse and variable levels of light and has dense cloud cover over 90% of the sky. This paper was calculated by a Desktop Radiance program. The space dimensions were based on a unit module of real constructed apartment having divided into five sections such as living room, room1, room2, room3 and kitchen.

• 한국실내디자인학회논문집
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• 제18권6호
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• pp.77-84
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• 2009

Daylighting is one of the major elements in architectural design. It also plays an important role in the museums focused on displaying artistic works. Many architects have tried to predict daylighting performances in exhibition spaces during the design process of museums. The aims of this study are to present the design methods using the computer program RADIANCE that is available for the evaluations of daylighting performances in indoor space and to help architects design daylighting systems for better exhibition spaces of museums. For this study, Seoul Museum of Art was chosen and it was evaluated the recommended illuminance and the impacts of direct sunlight under the conditions of overcast sky and clear sky with sun. According to simulation results, they indicated that the alternative toplight system(sawtooth shape) was more effective for daylighting of exhibition spaces than the existing toplight system(pyramid shape) and this study showed a method to evaluate daylighting effects in exhibition spaces with various shapes of toplight systems.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2002년도 학술대회논문집
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• pp.91-95
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• 2002

This study is using the RADIANCE lighting simulation tool to determine the transmittance where the horizontal blind is installed. The transmittance is applied to DayDim program which is a lighting calculation and analysis tool. Parameters such as clear sky type, seasonal changes(the summer solstice), altitude, azimuth and horizontal blind angle at a 0$^{\circ}$, 45$^{\circ}$, 90$^{\circ}$ were considered. The simulation results present that measured directional transmittances have different values according to each directional property of the horizontal blind.

• KIEAE Journal
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• 제5권3호
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• pp.3-9
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• 2005

Venetian blinds are used with windows to improve the uniformity ratio of illuminance and interior daylighting distribution under direct sunlit conditions. The main objective of Venetian blinds shading system is to obstruct direct sunlight and at the same time allow daylight to penetrate into the room. Venetian blinds would have greater effect on the interior daylighting condition under clear sky which has both skylight and sunlight than overcast sky which has only skylight. However, due to the lack of data, design and evaluation tools, it is difficult for architects to choose or install venetian blinds during the building design stages. The purpose of this study was to develop an analysis method for shading and daylighting effects of Venetian blinds using the RADIANCE program. The major variables related to the venetian blinds included blinds's slat angle and the ratio of slat width to window height, the radius slat of curvature and the building azimuth. In this study, a series of parametric physical mock-up model measurements and genblinds command in the RADIANCE simulations. The results of this study will provide building designers with the design data at early design stages.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.282-285
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• 2007

Satellite observed brightness temperature simulation using a radiative transfer model (here after, RTM) is useful for various fields, for example sensor design and channel selection by using theoretically calculated radiance data, development of satellite data processing algorithm and algorithm parameter determination before launch. This study is focused on elaborating the simulation procedure, and analyzing of difference between observed and modelled clear sky brightness temperatures. For the CMDPS (COMS Meteorological Data Processing System) development, the simulated clear sky brightness temperatures are used to determine whether the corresponding pixels are cloud-contaminated in cloud mask algorithm as a reference data. Also it provides important information for calibrating satellite observed radiances. Meanwhile, simulated brightness temperatures of COMS channels plan to be used for assessing the CMDPS performance test. For these applications, the RTM requires fast calculation and high accuracy. The simulated clear sky brightness temperatures are compared with those of MTSAT-1R observation to assess the model performance and the quality of the observation. The results show that there is good agreement in the ocean mostly, while in the land disagreement is partially found due to surface characteristics such as land surface temperature, surface vegetation, terrain effect, and so on.

• 대한원격탐사학회지
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• 제16권4호
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• pp.305-313
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• 2000

A vicarious calibration method was developed for the OSMI sensor calibration. Employing measured aerosol optical thickness by a sunphotometer and a sky radiometer and water leaving radiance by ship measurements as inputs, TOA (top of the atmosphere) radiance at each OSMI band was simulated in conjunction with a radiative transfer model (Rstar5b) by Nakajima and Tanaka (1988). As a case of examining the accuracy of this method, we simulated TOA radiance based on water leaving radiance measured at NASA/MOBY site and aerosol optical thickness estimated nearby at Lanai, and compared simulated results with SeaWiFS-estimated TOA radiances. The difference falls within about $\pm$5%, suggesting that OMSI sensor can be calibrated with the suggested accuracy. In order to apply this method for the OSMI sensor calibration, ground-based sun photometry and ship measurements were carried out off the east coast of Korean peninsula on May 31, 2000. Simulations of TOA radiance by using these measured data as input to the radiative transfer model show that there are substantial differences between simulated and OSMI-estimated radiances. Such a discrepancy appears to be mainly due to the cloud contamination because satellite image indicates optically thin clouds over the experimental area. Nevertheless results suggest that sensor calibration can be achieved within 5% uncertainty range if there are ground-based measurements of aerosol optical thickness, and water leaving radiances under clear-sky and optically thin atmospheric conditions.

• 대한원격탐사학회지
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• 제34권6_1호
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• pp.1101-1117
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• 2018

청천복사휘도는 히마와리-8호 정지궤도 기상위성에서 제공되는 주요 산출물 중의 하나로서, 자료동화 과정을 통해 수치예보 정확도 향상에 기여한다. 특히, 청천복사휘도는 대기운동벡터와 함께 대기 상층에서 자료동화의 효과를 보인다. 본 연구에서는 히마와리-8호 청천복사휘도의 편차 특성 분석과 평가를 통해 자료를 활용하는 사용자에게 정보를 제공해주고, 효과적으로 자료를 사용할 수 있도록 수치예보모델자료를 활용한 편차와 불확실성을 계산하였다. 일본 기상청에서 제공되는 청천복사휘도를 관측 자료로 사용하였고, 17 km 공간해상도의 기상청 전구 모델 Unified Model(UM) 자료와 복사전달모델 RTTOV-v11.2를 이용하여 청천복사휘도를 모의하였다. 먼저, 관측자료의 특성을 파악하고 관측자료와 모의된 청천복사휘도의 채널별 편차특성을 분석하였다. 전반적인 결과는 히마와리-8호 위성의 세 개의 수증기 채널(6.2, 6.9, $7.3{\mu}m$)에서는 양의 편차를 보인 반면에 대기창 적외 채널(10.4, 11.2, $12.4{\mu}m$)에서는 음의 편차를 보였다. 또한 분석결과는 계절과 영역에 따라 상이하게 나타났으며, 특히 사막이나 고지대 지역의 편차 특성이 뚜렷하게 나타났다. 이를 통해 청천복사자료를 활용할 때 시공간적인 특성을 고려해야 함을 확인할 수 있었다. 본 연구의 결과는 히마와리-8호 AHI의 청천복사휘도를 자료동화 할 때 전처리 과정에서 유용하게 활용될 수 있을 것이며, 2018년에 발사된 천리안-2A호의 산출물 활용에도 도움이 될 것으로 기대한다.

• Architectural research
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• 제4권1호
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• pp.17-23
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• 2002

Daylight simulation methods play an important role for the prediction of daylight illuminances in underground spaces. This daylighting project is designed to compare daylight prediction methods for the application of large underground spaces. In this study, actual measurements were conducted under overcast and clear sky conditions. Also, computer simulations by Radiance, Superlite IEA 2.0 program and scale model testings were conducted to be compared with measured data. Simulation results show the data by Radiance, Superlite IEA 2.0 and the scale model are similar to the measured data in two underground spaces in Seoul. Overall results show that Radiance and superlite IEA 2.0 proved to be useful to predict daylight illuminances even in big underground spaces.

• KIEAE Journal
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• 제13권3호
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• pp.97-104
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• 2013

This proposed simulation-based design study is based on the design of residential high-rise buildings in South-Korea. the purpose of this study is to evaluate the amount of daylighting performance passing through building glazing according to sky conditions, orientation of windows and each space of Apartment buildings. The clear sky includes sunshine and is intense and brighter at the horizon than at the zenith, except in the area around the sun. Daylight received within a building is directly dependent upon the sun's position and the atmospheric conditions. Orientation of the building generally used to refer to solar orientation which is the siting of building with respect to solar access. Although any building will have different orientations for its different sides, the orientation can refer to a particular room, or to the most important facade of the building. north-facing windows receive twice the winter sun than east and west facing windows, allowing light and warmth into the home. They can be easily shaded from the high summer sun to help keep the house cool. Ideally, the glazing area should be between 10-25% of the floor area of the room. This paper was calculated by a Desktop Radiance program. The space dimensions were based on a unit module of real constructed apartment having divided into five sections such as living room, room1, room2, room3 and kitchen.