• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.1-9
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• 2001

This research chose the existing designed copier zoom lens system and analyzed to calculate the optical capacity. As this lens system was the zoom lens system of finite object point, differed form the general camera zoom lens of infinite object point, it got a limited movement range because it moved between the fixed object and the image. In the result of comparison the optical capacities between a symmetric form and a asymmetric form. We could find out the truth which a asymmetric form constituted comparative stable aberrations and existed a tracks of effort for aberration correction. Therefore, a symmetric form is allotted satisfactorily from improved aberrations by itself in the fixed focal lens system. However, it has a limit of improving for capacity when it is used a zoom lens system got a symmetric form.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.119-125
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• 2000

We analyzed to calculate optical capacity after we chose established 2 component zoom copier lens system in this research. As the lens system is zoom lens system of finite object point, it has moving area limited not like to use generally camera zoom lens of infinite object point because it moves between object and image plane. The magnification of optical system can obtain -1.41~-0.64 i.e., extended or shortened image as transverse magnification, and it acquires f/12 and about $20^{\circ}$ field of view. Although this 2 component zoom copier lens system will be down resolution and dark compared with f/2.8 acquired at camera lens, it will be possibile to be able to make large aperture and it can acquire more better correct aberration with the addition of auxiliary group forward or backward.

• Journal of the Korean earth science society
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• v.38 no.2
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• pp.129-140
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• 2017

Global solar radiation was calculated in this research using ground-base measurement data, meteorological satellite data, and GWNU (Gangneung-Wonju National University) solar radiation model. We also analyzed the accuracy of the GWNU model by comparing the observed solar radiation according to the total cloud cover. Our research was based on the global solar radiation of the GWNU radiation site in 2012, observation data such as temperature and pressure, humidity, aerosol, total ozone amount data from the Ozone Monitoring Instrument (OMI) sensor, and Skyview data used for evaluation of cloud mask and total cloud cover. On a clear day when the total cloud cover was 0 tenth, the calculated global solar radiations using the GWNU model had a high correlation coefficient of 0.98 compared with the observed solar radiation, but root mean square error (RMSE) was relatively high, i.e., $36.62Wm^{-2}$. The Skyview equipment was unable to determine the meteorological condition such as thin clouds, mist, and haze. On a cloudy day, regression equations were used for the radiation model to correct the effect of clouds. The correlation coefficient was 0.92, but the RMSE was high, i.e., $99.50Wm^{-2}$. For more accurate analysis, additional analysis of various elements including shielding of the direct radiation component and cloud optical thickness is required. The results of this study can be useful in the area where the global solar radiation is not observed by calculating the global solar radiation per minute or time.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.2
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• pp.94-99
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• 2010

This paper presents a charge pump architecture for correcting the current mismatch due to the PVT variation. In general, the current mismatch of the charge pump should be minimized to improve the phase noise and spur performance of the PLL. In order to correct the current mismatch of the charge pump, the current difference is detected by the replica charge pump and fed back into the main charge pump. This scheme is very simple and guarantees the high accuracy compared with the prior works. Also, it shows a good dynamic performance because the mismatch is corrected continuously. It is implemented in 0.13um CMOS process and the die area is $100{\mu}m\;{\times}\;160{\mu}m$. The voltage swing is from 0.2V to 1V at supply voltage of 1.2V. The charging and discharging currents are $100{\mu}A$, respectively and the current mismatch due to the PVT variation is less than 1%.

• Korean Journal of Remote Sensing
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• v.29 no.4
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• pp.399-406
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• 2013

The quality of satellite imagery should be improved and stabilized to satisfy numerous users. The radiometric characteristics of an optical sensor can be a measure of data quality. In this study, a band aggregation technique and spectral response function of hyperspectral images are used to simulate multispectral images. EO-1 Hyperion and Landsat-8 OLI images acquired with about 30 minutes difference in overpass time were exploited to evaluate radiometric coefficients of OLI. Radiance values of the OLI and the simulated OLI were compared over three subsets covered by different land types. As a result, the index of agreement shows over 0.99 for all VNIR bands although there are errors caused by space/time and sensors.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.6
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• pp.796-803
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• 2003

The discrete ordinates interpolation method (DOIM) has shown good accuracy and versatile applicability for the radiation $problems^{(1,2)}$. The DOIM is a nonconservative method in that the intensity and temperature are computed only at grid points without considering control volumes. However, when the DOIM is used together with a finite volume algorithm such as $SIMPLER^{(3)}$, intensities at the control surfaces need to be calculated. For this reason, a 'quadratic' and a 'decoration' schemes are proposed and examined. They are applied to two kinds of radiation problem in one-dimensional geometries. In one problem, the intensity and temperature are calculated while the radiative heat source is given, and in the other, the intensity and the radiative heat source are computed with a given temperature field. The quadratic and the decoration schemes show very successful results. The quadratic scheme gives especially accurate results so that further decoration may not be needed. It is recommended that the quadratic and the decoration schemes may be used together, or, one of them may be applied for control volume radiative energy balance.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.326-326
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• 2022

기후 변화 시나리오는 온실가스, 에어로졸, 토지이용 변화 등 인위적인 원인으로 발생한 복사강제력 변화를 지구시스템 모델에 적용하여 산출한 미래 기후 전망정보(기온, 강수량, 바람, 습도 등)를 생산하는데 활용된다. 또한, 미래에 기후변화로 인한 영향을 평가하고 피해를 최소화하는데 활용할 수 있는 선제적인 정보로 활용된다. GCM과 RCM은 구조 및 모수화 과정, 불확실성 등의 한계로 인하여 상대적으로 큰 시공간적 규모를 가지며, 실제 관측된 기상인자들을 재현하는데 시공간적 차이 즉 편의(bias)가 발생하며. 실제 관측된 기상인자의 시간적 변화 특성을 재현하지 못하는 문제점을 내재하고 있는 것으로 보고되고 있다. 이러한 점에서 기후모델에서 생산된 정보를 수문학적으로 적용하기 위해서는 시공간적 상세화와 편의 보정은 필수적이다. 본 연구에서는 관측자료를 사용하여 재해석 자료를 편의보정 한 뒤. 기후 변화 시나리오를 합성곱 신경망(CNN)을 기반으로 상세화 과정을 진행하여 고해상도 자료를 생산하였으며, CNN 기반 상세화 기법 적용성은 지상 관측자료 대상으로 평가하였다.

• The KIPS Transactions:PartB
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• v.16B no.4
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• pp.289-298
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• 2009

Active Contour Model, that is, Snake algorithm is effective for detection and tracking the objects. However, this algorithm has some drawbacks; numerous parameters must be designed(weighting factors, iteration steps, etc.), a reasonable initialization must be available and moreover suffers from numerical instability. Therefore we propose a novel Energy Corrected Snake(ECS) algorithm which improved on external energy of Snake algorithm for detection and tracking the moving object more effectively. The proposed algorithm uses the difference image, getting when the object is moving. It copies four direction images from the difference image and performs the accumulating compute to erasing image noise, so that it gets external energy steadily. Then external energy united with contour that is computed by internal energy. Consequently we can detect and track the moving object more speedily and easily. To show the effectiveness of the proposed algorithm, we experiment on 3 situations. The experimental results showed that the proposed algorithm outperformed by 6$\sim$9% of detection rate and 6$\sim$11% of tracker detection rate compared with the Snake algorithm.

• Korean Journal of Remote Sensing
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• v.37 no.6_3
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• pp.1951-1963
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• 2021

Remote sensing data using earth observation satellites in agricultural environment monitoring has many advantages over other methods in terms of time, space, and efficiency. Since the sensor mounted on the satellite measures the energy that sunlight is reflected back to the ground, noise is generated in the process of being scattered, absorbed, and reflected by the Earth's atmosphere. Therefore, in order to accurately measure the energy reflected on the ground (radiance), atmospheric correction, which must remove noise caused by the effect of the atmosphere, should be preceded. In this study, atmospheric correction sensitivity analysis, inter-satellite cross-analysis, and comparative analysis with ground observation data were performed to evaluate the application of KOMPSAT-3 satellite's atmospheric correction for agricultural application. As a result, in all cases, the surface reflectance after atmospheric correction showed a higher mutual agreement than the TOA reflectance before atmospheric correction, and it is possible to produce the time series vegetation index of the same standard. However, additional research is needed for quantitative analysis of the sensitivity of atmospheric input parameters and the tilt angle.

• Korean Journal of Remote Sensing
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• v.39 no.6_2
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• pp.1529-1539
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• 2023

The data from Geostationary Ocean Color Imager-II (GOCI-II), which observes the color of the sea to monitor marine environments, undergoes various correction processes in the ground station system, producing data from Raw to Level-2 (L2). Quality issues arising at each processing stage accumulate step by step, leading to an amplification of errors in the satellite data. To address this, improvements were made to the GOCI-II ground station system to measure potential optical quality and geolocation accuracy errors in the Level-1A/B (L1A/B) data. A newly established Radiometric and Geometric Performance Assessment Module (RGPAM) now measures five optical quality factors and four geolocation accuracy factors in near real-time. Testing with GOCI-II data has shown that RGPAM's functions, including data processing, display and download of measurement results, work well. The performance metrics obtained through RGPAM are expected to serve as foundational data for real-time radiometric correction model enhancements, assessment of L1 data quality consistency, and the development of reprocessing strategies to address identified issues related to the GOCI-II detector's sensitivity degradation.