• KIEAE Journal
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• 제15권1호
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• pp.83-88
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• 2015

This study aims to develope the light-weight PV blinds with windows and to investigate the shading analysis by the control conditions. For the study, the polycarbonate characteristics and coating methods are analyzed and the PV blind design for a small office is suggested. Also, the mock-up model of a suggesting system was made. The field tests were controled based on a solar altitude under clear sky conditions. As results, it is necessary to use a polycarbonate instead of a tempered glass for a light-weight PV. The shading effects of blind systems are high in slat angle $30^{\circ}$ and low in $0^{\circ}$. Also, the shading ratio is more affected by solar latitude than solar altitude. The shading change rate is relevantly constant on the solar altitude.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.34-37
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• 2005

An efficient and robust neural network-based scheme is introduced in this paper to perform automatic cloud detection. Unlike many existing cloud detection schemes which use thresholding and statistical methods, we used the artificial neural network methods, the multi-layer perceptrons (MLP) with back-propagation algorithm and radial basis function (RBF) networks for cloud detection from Geostationary satellite images. We have used a simple scene (a mixed scene containing only cloud and clear sky). The main results show that the neural networks are able to handle complex atmospheric and meteorological phenomena. The experimental results show that two methods performed well, obtaining a classification accuracy reaching over 90 percent. Moreover, the RBF model is the most effective method for the cloud classification.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.404-408
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• 1998

Yellow sand event has been studied using SeaWiFS data in order to examine the aerosol optical characteristics in the Yellow Sea and their influences on the atmospheric correction for the ocean color remote sensing. Two SeaWiFS images of April 18 and April 25, 1998, representing Yellow Sand event and clear-sky case respectively, are selected for emphasizing the impact of high aerosol concentration on the ocean color remote sensing. It was shown that NASA's standard atmospheric correction algorithm treats yellow sand area as either too high radiance or cloud area, in which ocean color information is not generated. SeaWiFS aerosol optical thickness is compared with nearby ground-based sun photometer measurements and also is compared with radiative transfer simulation in conjunction with yellow sand model, examining the performance of NASA's atmospheric correction algorithm in case of the heavy dust event.

• KIEAE Journal
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• 제4권4호
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• pp.45-52
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• 2004

Simulation of daylighting by computer program is a method to avoid unnecessary efforts in manufacture of its testing models, to reduce its measuring tolerances and be able to provide variations of various weather conditions as well. Many simulation programs on daylighting have been released freely or commercialized for selling, however, a demonstration of their availability and validity as a tool for evaluating daylighting performance is required since each one has its own characteristics. The objectives of this study lie in suggesting an application method of evaluation tools and demonstration of limits and characteristics so as to more easily determine the daylightingperformance in the very initial stages of planning for an arbitrary office space in which windows with daylight access are built. We produced scale model of the general light inducing type side lighting with lightshelfand ceiling, and the luminance (at 78 measuring points) and illuminance (at 84 measuring points) were measured in a clear sky. And a comparison of the measured values and the calculated values from a computer simulation using the Lightscape program was performed.

• Advances in Energy Research
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• 제8권2호
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• pp.111-123
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• 2022

Solar Energy is the energy of solar radiation carried by them in the form of heat and light. It can be converted into electricity. Solar potential depends on the site's atmosphere; the solar energy distribution depends on many factors, e.g., turbidity, cloud types, pollution levels, solar altitude, etc. We estimated solar radiation with the help of the Ashrae clear-sky model for three locations in Pakistan, namely Pasni, Gwadar, and Jiwani. As these locations are close to each other as compared to the distance between the sun and earth, therefore a slight change of latitude and longitude does not make any difference in the calculation of direct beam solar radiation (BSR), diffuse solar radiation (DSR), and global solar radiation (GSR). A modified formula for declination angle is also developed and presented. We also created two different models for Ashrae constants. The values of these constants are compared with the standard Ashrae Model. A good agreement is observed when we used these constants to calculate BSR, DSR, GSR, the Root mean square error (RMSE), Mean Absolute error (MABE), Mean Absolute percent error (MAPE), and chisquare (χ²) values are in acceptance range, indicating the validity of the models.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.655-659
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• 2006

Surface Solar Insolation is important for vegetation productivity, hydrology, crop growth, etc. In this study, Surface Solar Insolation is estimated using Multi-functional Transport Satellite (MTSAT-1R) in clear and cloudy conditions. For the Cloudy sky cases, the surface solar insolation is estimated by taking into account the cloud transmittance and multiple scattering between cloud and surface. This model integrated Kawamura's model and SMAC code computes surface solar insolation with a 5km ${\times}$ 5km spatial resolution in hourly basis. The daily value is derived from the available hourly Surface Solar Insolation, independently for every pixel. To validation, this study uses ground truth data recorded from the pyranometer installed by the Korea Meteorological Agency (KMA). The validation of estimated value is performed through a match-up with ground truth. Various match-up with ground truth. Various match-up window sizes are tested with 3${\times}$3, 5${\times}$5, 7${\times}$7, 9${\times}$9, 10${\times}$10, 11${\times}$11, 13${\times}$13 pixels to define the spatial representativity of pyranometer measurement, and to consider drifting clouds from adjacent pixels across the ground station during the averaging interval of 1 hour are taken into account.

• 대한원격탐사학회지
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• 제22권5호
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• pp.389-396
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• 2006

Surface Solar Insolation is important for vegetation productivity, hydrology, crop growth, etc. In this study, Surface Solar Insolation is estimated using Multi-functional Transport Satellite (MTSAT-1R) in clear and cloudy conditions. For the Cloudy sky cases, the surface solar insolation is estimated by taking into account the cloud transmittance and multiple scattering between cloud and surface. This model integrated Kawamura's model and SMAC code computes surface solar insolation with a $5\;km{\times}5\;km$ spatial resolution in hourly basis. The daily value is derived from the available hourly Surface Solar Insolation, independently for every pixel. To validation, this study uses ground truth data recorded from the pyranometer installed by the Korea Meteorological Agency (KMA). The validation of estimated value is performed through a match-up with ground truth. Various match-up with ground truth. Various match-up window sizes are tested with $3{\times}3,\;5{\times}5,\;7{\times}7,\;9{\times}9,\;10{\times}10,\;11{\times}11,\;13{\times}pixels to define the spatial representativity of pyranometer measurement, and to consider drifting clouds from adjacent pixels across the ground station during the averaging interval of 1 hour are taken into account.

• 한국측량학회지
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• 제30권6_1호
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• pp.519-528
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• 2012

SAR는 기상상태와 태양고도 제약을 받지 않고 영상을 취득할 수 있는 장점을 갖지만 측면 관측 촬영방식으로 인해 고도에 의한 왜곡이 발생하여 광학영상과의 통합적 활용을 위해서는 지형 보정 작업이 필수적이다. 일반적으로 SAR 영상의 지형보정은 대상지역의 수치표고모델(Digital Elevation Model, DEM)을 사용하여 수행되기 때문에 DEM 품질이 지형보정 정확도에 미치는 영향에 대한 평가가 이루어져야 한다. 이를 위해 본 연구에서는 1:5000 수치지도로부터 제작한 DEM, LiDAR DEM, ASTER GDEM, SRTM DEM을 비교 분석하여 고해상도 SAR 영상의 지형보정에 적합한 DEM을 탐색하였다. 실험데이터로는 KOMPSAT-5호와 동일한 고해상도 X-band SAR 시스템을 장착한 TerraSAR-X와 Cosmo-SkyMed 영상을 사용하였다. 지형보정 결과 평가를 위해 동일지역의 KOMPSAT-2 정사영상과의 정량적 비교평가를 수행하였다. 실험결과 수치지도로 제작한 DEM이 가장 정확한 지형보정 결과를 보였으며 현업에서 가장 많이 활용되고 있는 SRTM DEM의 경우 고해상도 SAR 영상의 지형보정에는 부적합 하였다.

• 천문학논총
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• 제27권4호
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• pp.353-356
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• 2012

We present new constraints on the cosmic optical background (COB) obtained from an analysis of the Pioneer 10/11 Imaging Photopolarimeter (IPP) data. After careful examination of the data quality, the usable measurements free from the zodiacal light are integrated into sky maps at the blue (${\sim}0.44{\mu}m$) and red (${\sim}0.64{\mu}m$) bands. Accurate starlight subtraction was achieved by referring to all-sky star catalogs and a Galactic stellar population synthesis model down to 32.0 mag. We find that the residual light is separated into two components: one component shows a clear correlation with the thermal $100{\mu}m$ brightness, whilst the other shows a constant level in the lowest $100{\mu}m$ brightness region. The presence of the second component is significant after all the uncertainties and possible residual light in the Galaxy are taken into account, thus it most likely has an extragalactic origin (i.e., the COB). The derived COB brightness is ($(1.8{\pm}0.9){\times}10^{-9}$ and $(1.2{\pm}0.9){\times}10^{-9}\;erg\;s^{-1}\;cm^{-2}\;sr^{-1}\;{\AA}^{-1}$ in the blue and red spectral regions, respectively, or $7.9{\pm}4.0$ and $7.7{\pm}5.8\;nW\;m^{-2}\;sr^{-1}$. Based on a comparison with the integrated brightness of galaxies, we conclude that the bulk of the COB is comprised of normal galaxies which have already been resolved by the current deepest observations. There seems to be little room for contributions from other populations including "first stars" at these wavelengths. On the other hand, the first component of the IPP residual light represents the diffuse Galactic light (DGL)-scattered starlight by the interstellar dust. We derive the mean DGL-to-$100{\mu}m$ brightness ratios of $2.1{\times}10^{-3}$ and $4.6{\times}10^{-3}$ at the two bands, which are roughly consistent with previous observations toward denser dust regions. Extended red emission in the diffuse interstellar medium is also confirmed.

• 대한원격탐사학회지
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• 제17권3호
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• pp.211-218
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• 2001

대기복사모델인 MODTRAN을 이용해 다목적실용위성 2호 탑재체인 Multispectral Camera (MSC)의 총복사량에 대한 계산을 수행하고 그 결과를 분석해 보았다. 모델 계산에서 4계절 조건을 모의실험하기 위해 1월 15일, 7월 15일 계산에 대해 중위도 동절기 및 하절기 모델대기를, 4월 15일, 10월 15일에 대해 US 표준대기를 각각 사용했다. 다목적실용위성 2호 궤도 조건과 각 계절에 대한 대표적인 태양천정각 (solar zenith angle)이 고려되었다. 시정거리는 대류권 에어로솔 소광계수 (tropospheric aerosol extinction)에 해당하는 50km가, 지표의 알베도는 맑은 날 지구 연평균 값에 해당하는 0.135가 가정되었다. MSC 계약서 값은 위 일반적 조건을 가정하고 얻은 모델 계산 총복사량보다 MSC 관측 파장대역 대부분에서 상당히 크다는 것을 알게 되었다. 또한 균일한 지표 알베도를 가정하고 얻은 모델 결과의 분광파장 특징이 MSC 계약서 값의 경향과 다름을 보였다. 이들 결과로부터 향후 획득될 MSC영상은 비교적 어두운 영상이 될 것으로 추론된다.