• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.633-636
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• 2005

An electro-optical camera system consists of many subsystems such as the optics, the detector, and the electronics and so on. They may create variations in the processed image that were not present original scene. The performance analysis of the electro-optical camera system is a mathematical construct that provides an optimum design through appropriate trade off analysis. The SNR(Signal to Noise Ratio) is one of the most important performance for the electro-optical camera system. The SNR analysis shown in this paper is performed based on the practical high resolution satellite camera design. For the purpose of the practical camera design, the analysis assumes that the defined radiance, which is calculated for the Korean peninsula, reached directly to the telescope entrance. In addition, the actual operation concept such as integration time and the normal operation altitude is assumed. This paper compares the SNR analysis results according to the various camera characteristics such as the optics, the detector, and the camera electronics. In detail, the optical characteristics can be split into the focal length, F#, transmittance, and so on. And the system responsivity, the quantum efficiency, the TDI stages, the quantization noise and the analogue noise can be used for the detector and the camera electronics characteristics. Finally this paper suggests the optimum design to apply the practical electro-optical system.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.604-607
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• 2005

All CCD pixels do not react uniformly even if the light of same radiance enters into the camera. This comes from the different camera optical characteristics, the read-out characteristics, the pixel own characteristics and so on. Usually, the image data of satellite camera can be corrected by the various image-processing methods in the ground. However, sometimes, the in-orbit correction is needed to get the higher quality image. Especially high frequency pixel correction in the middle of in-orbit mission is needed because the in-orbit data compression with the high frequency loss is essential to transmit many data in real time due to the limited RF bandwidth. In this case, this high frequency correction can prevent have to have any unnecessary high frequency loss. This in-orbit correction can be done by the specific correction table, which consists of the gain and the offset correction value for each pixel. So, it is very important to get more accurate correction table for good correction results. This paper shows the new algorithm to get accurate pixel correction table. This algorithm shall be verified theoretically and also verified with the various simulation and the test results.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.219-219
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• 2009

ceramic metal halide lamps are a subset of high intensity discharge lamps so named because of their high radiance These lamps weak ionized plasma in a fire-resisting but light transmissive wrapping by the corridor of current through atomic and molecular vapors. for commercial applications, For commercial applications, the conversion of electric power to light must occur with good efficiency and with sufficient spectral content throughout the visible (380-800 nm) to permit the light so generated to render colors comparable to natural sunlight. the purpose of this paper is to carry out a study on the variation of ageing time(2000 On/Off[hr]) on the performance of 150W CMH lamps. Experimental results show that the blackening by reacting W(tungsten)with I atomic has been created in the arc tube of an ageing lamp(2000 On/Off[hr]), the arc was unstable, and increased a lamp resistance made lamp voltage increases significantly. Also, Color temperature of the ageing lamp was moved by the losses of Ho with Dy atomics and by recombination of Na with I.

• 한국지구과학회지
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• 제26권2호
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• pp.109-113
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• 2005

In this study, the estimation of the temperature distribution of Jeju Island with coastal ocean derived from the thermal band of Landsat 7/ETM+ of January 6, 2003 was carried out. For the computation of the temperature of the island and the coastal ocean based on the thermal band, we used NASA method wiich is the 8 bit Digital Number(DN) converted into spectral radiance. The computed results showed that the land temperature variations were from 0 to 12 Celsius degrees, and a good agreement with the observation ones based on the method. However, the ocean surface temperature was not much changed ground 15 degree since the water was well mixed between the coastal and the offshore ocean. The interesting results were that the temperature distributions of the southern part(Seogwipo City) of Jeju Island were higher than those of the north one(Jeju City) by more than 2 Celsius degree at the same height although the distance between the Jeju and the Seogwipo is only about 35km in winter season. The reason was found that the solar irradiance intensity of the south part was stronger than the north one by Halla mountain in winter season only. From the results, we found that the seasonal variations of solar irradiation and the height of Mt. Halla were an important role of temperature distribution of Jeju Island.

• 정보과학회 논문지
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• 제44권4호
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• pp.411-416
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• 2017

적외선 표적의 정밀한 모델링을 위해서는 정확한 표면온도 계산이 필요하다. 본 논문에서는 전도, 대류, 복사를 고려한 복합 열해석 모듈을 소프트웨어로 구현하고, 이를 통하여 표적 재질 및 자세, 환경 요건에 따른 표적의 표면온도 해석을 수행 하였다. 구현된 결과는 상용 소프트웨어인 OKTAL-SE 와의 비교를 통하여 결과의 신뢰성을 검증하였다. 그 결과 자체 검증이 완료된 상용 소프트웨어인 OKTAL-SE 와 약 1% 이내의 오차를 보였다. 계산된 온도 결과를 바탕으로 적외선 표적 모델링을 수행하였으며 OKTAL-SE와의 연동을 통해 적외선 신호 해석을 수행하였다.

• 대기
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• 제20권4호
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• pp.495-503
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• 2010

Satellite data have an intrinsic problem due to a number of various physical parameters, which can have a similar effect on measured radiance. Most evaluations of satellite performance have relied on comparisons with limited spatial and temporal resolution of ground-based measurements such as soundings and in-situ measurements. In order to overcome this problem, a new way of satellite data evaluation is suggested with statistical tools such as empirical orthogonal function(EOF), and singular value decomposition(SVD). The EOF analyses with OMI and OMI HCHO over northeast Asia show that the spatial pattern show high correlation with population density. This suggests that human activity is a major source of as well as HCHO over this region. However, this analysis is contradictory to the previous finding with GOME HCHO that biogenic activity is the main driving mechanism(Fu et al., 2007). To verify the source of HCHO over this region, we performed the EOF analyses with vegetation and HCHO distribution. The results showed no coherence in the spatial and temporal pattern between two factors. Rather, the additional SVD analysis between $NO_2$ and HCHO shows consistency in spatial and temporal coherence. This outcome suggests that the anthropogenic emission is the main source of HCHO over the region. We speculate that the previous study appears to be due to low temporal and spatial resolution of GOME measurements or uncertainty in model input data.

• 대기
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• 제17권3호
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• pp.291-298
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• 2007

The precipitable water vapors (PWVs) obtained from Global Positioning System (GPS) and Microwave Radiometer (MWR) measurements have been compared for validation of precision of the GPS PWV at Daegwallyoung station for 21 days from Sep. 30 to Oct. 20, 2006. The GPS PWV is estimated using the delay of GPS signals due to the water vapor in the atmosphere with a local mean temperature equation, called HP model, and the MWR PWV by the combinational radiance observation of two channels (23.8 and 31.4 GHz). During the co-observation period, the MWR and GPS PWV show a similar trend, and the bias between the PWVs is 1.7 mm on average. When the bias is removed, the PWV of GPS gives good agreement with that of MWR, having about 1 mm for both the standard deviation and RMS error between the GPS and MWR PWV.

• 방송공학회논문지
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• 제23권3호
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• pp.369-382
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• 2018

본 논문은 딥 컨볼루션 뉴럴 네트워크(CNN)를 이용하여 행 별로 서로 다른 노출로 촬영된 단일 영상을 HDR 영상으로 변환하는 기법을 제안한다. 제안하는 알고리즘은 먼저 입력 영상에서 저조도 또는 포화로 인해 발생하는 정보 손실 영역을 CNN을 이용하여 복원하여 휘도맵을 생성한다. 또한, CNN 학습 과정에서 인간의 시각 인지 특성을 고려할 수 있는 손실 함수를 제안한다. 마지막으로 복원된 휘도맵에 디모자이킹 필터를 적용하여 최종 HDR 영상을 획득한다. 컴퓨터 모의실험을 통해 제안하는 알고리즘이 기존의 기법에 비해서 높은 품질의 HDR 영상을 취득하는 것을 확인한다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.274-277
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• 2006

KARI is currently developing a geostationary ocean color imager (GOCI) for COMS. We report the progress in integrated optical modeling and analysis for stray light suppression and the end-to-end instrument performance verification including in-orbit calibration. The Sun is modeled as the emitting light source and the selected area around Korean peninsular as the observation target that scatters the sun light towards GOCI in orbit. The optical ray tracing employing active geometric scaling was then used for precise characterization of the spatial and radiometric performance at the instrument focal plane. The analysis results show positive reduction in the simulated stray light level with the design improvement including baffles. It also indicates that the ray traced in-orbit radiometric performances are effective tools for the independent assessment of more traditional linear and quadratic equation based estimation of water leaving radiance. The concept of integrated GOCI optical model and the computational method are presented.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.651-654
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• 2006

Infrared channels of newly launched Japanese geostationary satellite, MTSAT-1R are compared with well calibrated MODIS/Terra infrared measurements at 3.7, 6.7, 11, 12 ${\mu}m$ bands. There are four steps in this intercalibration method: 1) data collection, 2) spectral response function correction, 3) data collocation, and 4) calculation of mean bias and conversion coefficients. In order to minimize the navigation error of MTSAT-1R, comparisons are made over the area in which the viewing angle of MTSAT-1R is less than 50$^{\circ}$. The calibration method was tested for August 2005 and within the 40$^{\circ}N$-40$^{\circ}S$, 100$^{\circ}$E-180$^{\circ}$E domain. The differences of spectral response functions were corrected through radiative transfer model simulation. Constructing collocated data differences in viewing geometry, observation time and space were taken into account. In order to avoid the radiance variation induced by cloud presence, clear-sky targets are selected as intercalibration target. The mean biases of 11, 12, 6.7, and 3.7 ${\mu}m$ bands are about -0.16, 0.36, 1.31, and -6.69 K, suggesting that accuracies of 3.7 ${\mu}m$ is questionable while other channels are comparable to MODIS