• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.6
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• pp.118-125
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• 2011

In this paper, a WCDMA experimental base station is constructed for power management of mobile communication base station and effective isotropic radiated power is determined by using received power of pilot channel measured on the line-of sight. The measurement system was constructed by a experimental base station and a measurement receiver and the common pilot channel (CPICH) power of the base station was measured. Effective isotropic radiated power (EIRP) of the base station obtained by the measurement value considering correction factor for the errors represented the difference of 0.5 dB compared to the established EIRP of the base station.

• Korean Journal of Remote Sensing
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• v.29 no.2
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• pp.209-218
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• 2013

The Sonoran Desert, which is located in North America, has been frequently used for vicarious calibration of many optical sensors in satellites. Although the desert area has good conditions for vicarious calibration (e.g. high reflectance, little vegetation, large area, low precipitation), its adjacency to the sea and large variability in atmospheric water vapor are the disadvantages for vicarious calibration. For vicarious calibration using top-of-atmospheric (TOA) reflectance, the atmospheric variability brings about degraded precision in vicarious calibration results. In this paper, the location with the smallest radiometric variability in TOA reflectance is sought by using 12-year Landsat 5 data, and corrected the TOA reflectance for bidirectional reflectance distribution function (BRDF) which is another major source of variability in TOA reflectance. Experiments show that the mid-western part of the Sonoran Desert has the smallest variability collectively for visible and near-infrared bands, and the variability from the sunarget-sensor geometry can be reduced by the BRDF correction for the visible bands, but not sufficiently for the infrared bands.

• Journal of Climate Change Research
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• v.1 no.2
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• pp.147-161
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• 2010

The temporal and spatial distributions of surface solar radiation were calculated by the one layer solar radiative transfer model(GWNU) which was corrected by multi layer Line-by-Line(LBL) model during 2009 in South Korea. The aerosol optical thickness, ozone amount, cloud fraction and total precipitable water were used as the input data for GWNU model run and they were retrieved from Moderate Resolution Imaging Spectrometer(MODIS), Ozone Monitoring Instrument(OMI), MTSAT-1R satellite data and the Regional Data Assimilation Prediction System(RDAPS) model result, respectively. The surface solar radiation was calculated with 4 km spatial resolution in South Korea region using the GWNU model and the results were compared with surface measurement(by pyranometer) data of 22 KMA solar sites. The maximum values(more than $5,400MJ/m^2$) of model calculated annual solar radiation were found in Andong, Daegu and Jinju regions and these results were corresponded with the MTSAT-1R cloud amount data. However, the spatial distribution of surface measurement data was comparatively different from the model calculation because of the insufficient correction and management problems for the sites instruments(pyranometer).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.65-70
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• 2003

In this work variations of orbital parameters are first derived from the perturbation equations using difference equation method under Earth oblateness and atmospheric drag. A simple and effective scheme is proposed to compute the required delta v and fuel consumption to compensate for atmospheric drag. The scheme is applied to KOMPSAT example. And by means of numerical simulations we quantitatively analyze influences due to each perturbation source, i.e., nonspherical Earth, atmospheric drag, third body gravities (Sun, Moon), and solar radiation.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.4
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• pp.45-59
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• 2006

In this study, the effects of the surface topographical characteristics on the meteorological fields are examined in a mesoscale meteorlolgical model. We calculated the direct solar radiation using the illumination angle considering the inclination of topography and tried to find out its effect on meteorological fields. In above experiments, we selected two cases for the clear day and the cloudy day to show the effect of weather and represented the results for two cases. In the correction of the direct solar radiation, the results of two cases indicate that there are obvious differences on the steep Taeback and Soback mountains. And on the time-series analysis the east-facing slope of these mountains receives the more direct solar radiation about $10-60W/m^2$ in the morning hours but lesser in the afternoon hours than the horizontal surface while it is opposite on the west-facing slope. And the results mentioned above are more obvious at clear day. With the same analysis method, at clear day, the surface skin temperature is higher at all hours than that on horizontal surface on the both of slope. At cloudy and rainy day, the surface skin temperature on the east-facing slope is higher in the morning hours but lower in the afternoon hours than that on horizontal surface. But on the west-facing slope, it is higher at all hours than that on horizontal surface. In the two cases, the temperature considering the slope of surface is almost higher than that on the horizontal surface. The wind is stronger than that on the horizontal surface with increasing pressure gradient force according as increasing temperature gradient around the Taeback and the Soback mountains.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.40.1-40.1
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• 2010

인간의 삶과 밀접한 관련이 있는 태양 에너지는 전세계적으로 에너지 부족 문제 해결방안을 위한 대체 에너지 자원으로 각광 받고 있다. 즉 태양으로부터 방출되어 지표면에 도달하는 태양광은 연간 약 23,000 TW(Perez et al., 2009)로써 다른 어떤 종류의 에너지원보다 풍부하기 때문에 태양광 발전은 양적인 측면에서의 무한한 잠재력뿐만 아니라 환경적인 측면에서 무공해라는 장점을 가진다. 특히 국내에서는 2030년까지 태양광 에너지와 풍력 및 수소에너지들은 3대 국가 에너지 전략 분야로 집중 육성되고 있다(한국과학기술정보연구원, 2007). 지표면에 도달하는 태양 에너지 평가 및 분석을 위하여 일사계에 의한 관측 자료가 이용될 수 있으나 관측 영역 및 관측 정밀도 문제 때문에 태양 복사 모델(Solar Radiative Transfer Model)에 의한 계산 자료가 중요하게 활용된다. 이 연구에서 한반도의 지표면 태양광 계산을 위하여 사용된 모델은 Iqbal(1983)에 근거한 것으로써 단일 기층의 모형대기를 가정한 모델이며 상세 모델(Line-by-Line Model)에 의하여 보정하여 2009년 1월부터 2009년 12월까지 한반도의 지표면 태양광 시공간 분포를 계산하였다. 이 계산을 위하여 대기 중의 가스와 에어로졸 및 구름 성분들에 대한 모델 입력자료 등이 요구되며 이 자료들은 기상청의 수치 모델(Regional Date Assimilation and Prediction System; RDAPS)과 기상 관련 인공위성(OMI와 MODIS 및 MTSAT-1R 등)으로부터 발췌하여 사용하였다. 그 결과 이 연구 기간(2009년 1월 ~ 2009년 12월)동안 1 km 간격의 수평면에 대하여 계산된 한반도의 지표면 태양광은 안동과 대구 및 진주를 연결하는 지역에서 최대값($5400MJ/m^2$ 이상)이 나타났다. 그러나 지표면 일사 관측 자료의 공간 분포는 이 연구 결과와 차이가 있었으며 그 원인은 관측소 일사계의 보정 및 관리운영에 따른 자료 정확성 결여 때문으로 평가된다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1128-1139
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• 2013

KOMPSAT-5(KOrea Multi-Purpose SATellite-5) has a benefit of continuously conducting its mission in all weather and even night by loading SAR(Synthetic Aperture Radar) payload, which is different from optical sensor of KOMPSAT-2 satellite. During IOT(In-Orbit Test) periods, SAR image calibration should be conducted through ground target of which location and RCS is pre-determined. Differently from the conventional corner reflector, active transponder has a capability to change its internal transfer gain and delay, which allows active transponder to be shown in a pixel of SAR image with very high radiance and virtual location. In this paper, the development of active transponder is presented from design to I&T(Integration and Test).

• Atmosphere
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• v.21 no.2
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• pp.151-162
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• 2011

One-layer solar radiation(GWNU; Gangneung-Wonju National University) model is developed in order to resolve the lack of vertical observations and fast calculation with high resolution. GWNU model is based on IQBAL(Iqbal, 1983) and NREL(National Renewable Energy Laboratory) methods and corrected by precise multi-layer LBL(Line-by-line) model. Input data were used 42 atmospheric profiles from Garand et al.(2001) for calculation of global radiation by the Multi-layer and one-layer solar radiation models. GWNU model has error of about -0.10% compared with LBL model while IQBAL and NREL models have errors of about -3.92 and -2.57%, respectively. Global solar radiation was calculated by corrected GWNU solar model with satellites(MODIS, OMI and MTSAT-1R), RDPS model prediction data in Korea peninsula in 2009, and the results were compared to surface solar radiation observed by 22 KMA solar sites. All models have correlation($R^2$) of 0.91 with the observed hourly solar radiation, and root mean square errors of IQBAL, NREL and GWNU models are 69.16, 69.74 and $67.53W/m^2$, respectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.1
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• pp.1-9
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• 2015

A remote sensed image simulation following to weather and season conditions can be performed by a reverse atmospheric correction which is a function of image preprocessing. In this study, we have made an experiment to generate the simulated image to the raw image, which is prior to the atmospheric corrected images under the specific weather conditions. The applied methods in this study were the Forster algorithm (1984) and 6S RTM (Radiative Transfer Model). The simulated images has been compared with the original image to analyze compliances. In fact, the results from 6S RTM method show better compliances than Forster, with a mean of RMSE of DN difference 9.35 and a mean of $R^2$ 0.7. In conclusion, a simulated image has practical feasibility when similar to the period and season as the reference image.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.4
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• pp.414-423
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• 2015

Array error analysis and correction of active array antenna are described in this paper. Array elements composed of radiator and TR(Transmit & Recive) module have error(magnitude and phase difference among array elements) which affects SLL(Side Lobe Level). Error affectedness level depends on ideal SLL according to antenna aperture weighting, number of array elements and antenna effective aperture. To satisfy required SLL, correction of array elements is necessary; adopted differently per errors, and weighted differently per shapes of antenna and required SLL. Errors of every individual element had been defined, performance of the antenna with or without error correction had been estimated and proved through near field test.