• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.6
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• pp.25-32
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• 1999

The purpose of this study is to analyse the accuracy of weather forecasts of temperature, precipitation probability , and sky condition and to evaluate the applicability of weather forecasts for the estimation of potential evapotranspiration for irrigation scheduling. Five weather station s were selected to compare forecasted and measured climatcal data. The error between forecasted and measured temperature was calculated and discussed. The accuracy of temperature forecast using relative frequency of the error was calculated . The temperature forecasting showed considerably high accuracy. Average sunshine hours for forecasted sky conditions were calculated and showed reasonable quality. From the reliability graphs, the forecasting precipation probabililty was reliable. Potential evapotranspirations were calculated and compared using forecast and measured temperatures. The weather forecast is considered usable for irrigation scheculing.

• Korean Institute of Interior Design Journal
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• v.18 no.6
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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.

• Journal of information and communication convergence engineering
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• v.22 no.1
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• pp.70-79
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• 2024

Bad weather conditions such as haze lead to a significant lack of visibility in images, which can affect the functioning and reliability of image processing systems. Accordingly, various single-image dehazing (SID) methods have recently been proposed. Existing SID methods have introduced effective visibility improvement algorithms, but they do not reflect the image's perspective, and thus have limitations that distort the sky area and nearby objects. This study proposes a new SID method that reflects the sense of space by defining the correlation between image brightness and haze. The proposed method defines the haze intensity by calculating the airlight brightness deviation and sets the weight factor of the depth map by classifying images based on the defined haze intensity into images with a large sense of space, images with high intensity, and general images. Consequently, it emphasizes the contrast of nearby images where haze is present and naturally smooths the sky region to preserve the image's perspective.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.1
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• pp.19-26
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• 2017

Surface air temperature ($T_{air}$) is a key variable for the meteorology and climatology, and is a fundamental factor of the terrestrial ecosystem functions. Satellite remote sensing from the Moderate Resolution Imaging Spectroradiometer (MODIS) provides an opportunity to monitor the $T_{air}$. However, the several problems such as frequent cloud cover and mountainous region can result in substantial retrieval error and signal loss in MODIS $T_{air}$. In this study, satellite-based $T_{air}$ was estimated under both clear and cloudy sky conditions in Gangwon Province using Aqua MODIS07 temperature profile product (MYD07_L2) and GCOM-W1 Advanced Microwave Scanning Radiometer 2 (AMSR2) brightness temperature ($T_b$) at 37 GHz frequency, and was compared with the measurements from the Automated Mountain Meteorology Stations (AMOS). The application of ambient temperature lapse rate was performed to improve the retrieval accuracy in mountainous region, which showed the improvement of estimation accuracy approximately 4% of RMSE. A simple pixel-wise regression method combining synergetic information from MYD07_L2 $T_{air}$ and AMSR2 $T_b$ was applied to estimate surface $T_{air}$ for all sky conditions. The $T_{air}$ retrievals showed favorable agreement in comparison with AMOS data (r=0.80, RMSE=7.9K), though the underestimation was appeared in winter season. Substantial $T_{air}$ retrievals were estimated 61.4% (n=2,657) for cloudy sky conditions. The results presented in this study indicate that the satellite remote sensing can produce the surface $T_{air}$ at the complex mountainous region for all sky conditions.

• Journal of the Korean Solar Energy Society
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• v.26 no.3
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• pp.33-43
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• 2006

Daylight dimming control system was analyzed for an indirect lighting system in a small office space with a double skin envelope system. Computer simulations were performed for photosensors with three shielding conditions. The photosensors were placed on the center of ceiling, and backwall. Three sky conditions defined by CIE were considered. Overall, control performance was not very excellent for all conditions. Fully-shielded photosensor achieved good control performance for some cases, but partially-shielded and unshielded photosensors failed to achieve target illuminance. The variation in desktop illuminance due to daylight was examined for a variety of daylight conditions. Linear correlation between desktop illuminance and photosensor illuminance was analyzed using ANOVA.

• Journal of the Korean earth science society
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• v.40 no.2
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• pp.119-134
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• 2019

In order to analyze the observational environment of solar radiation stations operated by the Korea Meteorological Administration (KMA), we used the digital elevation model (DEM) and the solar radiation model to calculate a topographical shading, sky view factor (SVF) and solar radiation by surrounding terrain. The sky line and SVF were calculated using high resolution DEM around 25 km of the solar stations. We analyzed the topographic effect by analyzing overlapped solar map with sky line. Particularly, Incheon station has low SVF whereas Cheongsong and Chupungryong station have high SVF. In order to validation the contribution of topographic effect, the solar radiation calculated using GWNU solar radiation model according to the sky line and SVF under the same meteorological conditions. As a result, direct, diffuse and global solar radiation were decreased by 12.0, 5.6, and 4.7% compared to plane surface on Cheongsong station. The 6 stations were decreased amount of mean daily solar radiation to the annual solar radiation. Among 42 stations, eight stations were analyzed as the urgent transfer stations or moving equipment quickly and more than half of stations (24) were required to review the observational environment. Since the DEM data do not include artifacts and vegetation around the station, the stations need a detail survey of observational environment.

• Atmosphere
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• v.21 no.1
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• pp.57-67
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• 2011

Aerosol lidar ratio (extinction-to-backscatter ratio) at 532 nm was determined using 4-year measurements of elastic-backscatter lidar and sky radiometer at Seoul National University of Seoul, Korea. The mean lidar ratio (with standard deviation) based on 4 years of measurements is found to be $61.7{\pm}16.5$ sr, and weak seasonal variations are noted with a maximum in JJA ($68.1{\pm}16.8$ sr) and a minimum in DJF ($57.2{\pm}17.9$ sr). The lidar ratios for clean, dust, and polluted conditions are estimated to be $45.0{\pm}9.5$ sr, $51.7{\pm}13.7$ sr, and $62.2{\pm}13.2$ sr, respectively. While the lidar ratio for the polluted condition is appears to be consistent with previous studies, clean and dust conditions tend to have larger ratios, compared to previous estimates. This discrepancy is thought to be mainly due to the anthropogenic aerosols existing throughout the year around Seoul, which may cause increased lidar ratios even for clean and dust conditions.

• Journal of the Korean earth science society
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• v.26 no.2
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• pp.149-159
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• 2005

Simultaneous observations of MODIS (Moderate-resolution Imaging Spectroradiometer) onboard the Aqua and Terra satellites and weather station at ground near the Inchon International Airport (37.2-37.7 N, 125.7-127.2 E) during the period from December 2002 to September 2004 have been utilized in order to analyze the characteristics of satellite-observed infrared (IR) and visible data under fog and clear-sky conditions, respectively. The differences $(T_{3.7-11})$ in brightness temperature between $3.75{\mu}m\;and\;11.0{\mu}m$ were used as threshold values for remote-sensing fog (or low clouds) from satellite during day and night. The $T_{3.7-11}$ value during daytime was greater by about 21 K when it was foggy than that when it was clear, but during nighttime fog it was less by 1.5 K than during nighttime clear-sky. The value was changed due to different values of emission of fog particles at the wavelength. Since the near-IR channel at $3.7{\mu}m$ was affected by solar and IR radiations in the daytime, both IR and visible channels (or reflectance) have been used to detect fog. The reflectance during fog was higher by 0.05-0.6 than that during clear-sky, and varied seasonally. In this study, the threshold values included uncertainties when clouds existed above a layer of fog.

• Journal of the Korean earth science society
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• v.34 no.3
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• pp.249-256
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• 2013

For the purpose of recording polarization of the earth's atmosphere, the entire sky was photographed using the all-sky camera when the Sun was just above the horizon. The ratio and width of polarization were defined using the photograph, and a method to measure them was developed. Time-series photography of the polarization ratio and its width enabled us to qualitatively analyze the polarization phenomena which changes depending on the weather conditions. Findings indicated that polarization was co-related with air pollutants in a meaningful way. The polarization phenomena of the Earth's atmosphere are influenced by air pollutants. The more air pollutants exist in the air, the lower polarization ratio and the bigger polarization width it has. It is suggested that air pollutants disperses more photons, which makes it possible to observe the polarization phenomena in the vast area of the sky.

• Journal of Environmental Science International
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• v.16 no.3
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• pp.261-267
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• 2007

In this study, the Slab Ocean Model (SOM) is coupled with an Atmospheric General Circulation Model (AGCM) which developed in University of Kangnung based on the land surface model of Biosphere-Atmosphere Transfer Scheme (BATS). The purposes of this study are to understand radiative role of clouds considering of the atmospheric feedback, and to compare the Clouds Radiative Forcing (CRF) come from the analyses using the clear-cloud sky method and CGCM. The new CGCM was integrated by using two sets of the clouds with radiative role (EXP-A) and without radiative role (EXP-B). Clouds in this two cases show the negative effect $-26.0\;Wm^{-2}$ of difference of radiation budget at top of atmosphere (TOA). The annual global means radiation budget of this simulation at TOA is larger than the estimations ($-17.0 Wm^{-2}$) came from Earth Radiation Budget Experiment (ERBE). The work showed the surface negative effect with $-18.6 Wm^{-2}$ in the two different simulations of CRF. Otherwise, sensible heat flux in the simulation shows a great contribution with positive forcing of $+24.4 Wm^{-2}$. It is found that cooling effect to the surface temperature due to radiative role of clouds is about $7.5^{\circ}C$. From this study it could make an accurate of the different CRF estimation considering either feedback of EXP-B or not EXP-A under clear-sky and cloud-sky conditions respectively at TOA. This result clearly shows its difference of CRF $-11.1 Wm^{-2}$.