• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2009년도 춘계학술대회 논문집
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• pp.254-259
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• 2009

In this study, Simplified Method for the Atmospheric Correction (SMAC) radiative transfer model (RTM) used to retrieve surface reflectance from MODIS Top Of Atmosphere (TOA) reflectance (MOD02). SMAC code provides coefficients which were previously yielded by Second Simulation of the Satellite Signal in the Solar Spectrum (6S) for each satellite sensor. We conducted error analysis of SMAC RTM using MOD02 over comparison with MODIS surface reflectance (MOD09) which was provided from 6S. It showed that low accuracy values such as, $R^2$ : 0.6196, Root Means Square Error (RMSE) : 0.00031, bias : - 0.0859. Thus sensitivity analysis of input parameters and coefficients was conducted to searching error sources. Coefficients about $\tau_p$ (average AOD) are more influence than any other coefficients of $\tau_{a550}$ (Aerosol Optical Depth at 550nm) from sensitivity test. Calibrated coefficients of $\tau_p$ from regression analysis were used to surface reflectance which showed that improve accuracy of surface reflectance ($R^2$ : 0.827, RMSE : 0.00672, bias : - 0.000762).

• 천문학회보
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• 제36권1호
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• pp.88.1-88.1
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• 2011

We present the FIMS/SPEAR FUV continuum map of The Taurus - Auriga - Perseus (TPA) complex, which is one of the largest local association of dark clouds located in (l,b)~([152,180],[-28,0]). We also present the result of FUV dust scattering simulation, which is based on Monte Carlo Radiative Transfer(MCRT) technique. Before the simulation we generate the model cloud using Hipparcos 77834 stars and the calculation of their E(B-V). From the density-integrated image and the cross section image of the modeled cloud we confirmed that the Taurus cloud is located in ~130pc. The cloud north of the California nebula is known for its two layered structure and we confirm that using the cross section image of the modeled cloud. In our modeled cloud, that two clouds are located at ~130pc and at ~300pc, respectively. Over the whole region the result image of simulation is well correlated with the diffuse FUV observed with FIMS/SPEAR. The dense core of the Taurus cloud, however, is not revealed completely in the map.

• 천문학회지
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• 제51권5호
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• pp.155-164
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• 2018

We present various infrared two-color diagrams (2CDs) using WISE data for asymptotic giant branch (AGB) stars and Planetary Nebulae (PNe) and investigate possible evolutionary tracks. We use the sample of 5036 AGB stars, 660 post-AGB stars, and 2748 PNe in our Galaxy. For each object, we cross-identify the IRAS, AKARI, WISE, and 2MASS counterparts. To investigate the spectral evolution from AGB stars to PNe, we compare the theoretical model tracks of AGB stars and post-AGB stars with the observations on the IR 2CDs. We find that the theoretical dust shell model tracks can roughly explain the observations of AGB stars, post-AGB stars, and PNe on the various IR 2CDs. WISE data are useful in studying the evolution of AGB stars and PNe, especially for dim objects. We find that most observed color indices generally increase during the evolution from AGB stars to PNe. We also find that $Fe_{0.9}Mg_{0.1}O$ dust is useful to fit the observed WISE W3-W4 colors for O-rich AGB stars with thin dust shells.

• 천문학회보
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• 제37권2호
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• pp.210.2-210.2
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• 2012

Using Fresnel reflection and Hapke BRDF model with Apollo 10084 soil sample's scattering properties, we constructed a real scale optical lunar model and used it to simulate lunar apparent albedo and moonshine. For Fresnel reflection, the refractive index of $1.68{\pm}0.5$ was used. For Hapke BRDF parameters from BUGs BRDF measurement, the single scattering with w=0.33, hot spot width h=0.017, average phase angle ${\zeta}$=-0.086 and Legendre polynomial coefficients b=0.308, c=0.425 in wavelength 700nm with two types of Henyey-Greenstein phase function was applied. The computation model includes the Sun as a Lambertian scattering sphere, emitting 1.5078 W/m2 at 700nm in wavelength. The Sun and Moon models were then imported into the IRT based radiative transfer computation. The trial simulation of the irradiance levels of moonshine lights shows that they agree well with the ROLO measurement data. We then estimate the lunar apparent albedo to 0.11. The results are to be compared with the measurement data.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1255-1257
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• 2003

This study proposes a single-channel satellite remote sensing algorithm for retrieving aerosol optical thickness over global ocean using FY-1C/1D data. An efficient lookup table (LUT)method is adopted in this algorithm to generate apparent reflectance in channel 1 and channel 2 of FY-1C/1D over ocean. The algorithm scale the apparent reflectance in cloud-free conditions to aerosol optical thickness using a state-of-art radiative transfer model 6S with input of the relative spectral response of channel 1 and 2 of FY-1C/1D. Monthly mean composite maps of the aerosol optical thickness have been obtained from FY-1C/1D global area coverage data between 2001 and 2003. Aerosol optical thickness maps can show the major aerosol source which are located off the west coast of northern and southern Africa, Arabian Sea and India Ocean. These result is very similar to other satellite sensors such as AVHRR and MODIS in the location area of heavy aerosol optical thickness over global ocean. The algorithm have been used to FY-1D operational performance and it is the first operational aerosol remote sensing product in China.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.667-669
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• 2003

A bio-optical model was developed specific for turbid and shallow waters. Special studies were carried out to estimate absorption and scattering properties as well as backscattering probability of suspended matter. The inversion of bio-optical model allows for direct retrieval of turbidity and chlorophyll- a from the visible-near infrared (VNIR) range sensor. Time-series satellite imagery from ASTER AM-1 sensor, were used to monitor the Laguna de Bay water quality condition. Spatial distribution of temperature for the lake was extracted from the thermal infrared (TIR) sensor. Corresponding field surveys were conducted to parameterize the bio -optical model. In-situ measurements include suspended particle and chlorophyll-a concentrations profiles from nephelometric devices and processing of water samples. Hyperspectral measurements were used to validate results of the bio -optical model and satellite- based estimation. This study provides a theoretical basis and a practical illustration of applying space- based measurements on an operational basis.

• 대한원격탐사학회지
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• 제32권1호
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• pp.67-71
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• 2016

The surface reflectance is essential to retrieval various indicators related land properties such as vegetation index, albedo and etc. In this study, we estimated surface reflectance using Himawari-8 / Advanced Himawari Imager (AHI) channel data. In order to estimate surface reflectance from Top of Atmosphere (TOA) reflectance, the atmospheric correction is necessary because all of the TOA reflectance from optical sensor is affected by gas molecules and aerosol in the atmosphere. We used Second Simulation of a Satellite Signal in the Solar Spectrum Vector (6SV) Radiative Transfer Model (RTM) to correct atmospheric effect, and Look-Up Table (LUT) to shorten the calculation time. We verified through comparison Himawri-8 / AHI surface reflectance and Proba-V S1 products. As a result, bias and Root Mean Square Error (RMSE) are calculated about -0.02 and 0.05.

• 대한기계학회논문집
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• 제12권5호
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• pp.1113-1120
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• 1988

본 연구에서는 4종류의 실험 모델을 채택하여 연소 반응용다공성 블럭(combu- stive reacting porous block)내의 화염대 위치와 화염의 온도 분포, 화염이 안정화 되는 범위를 고찰하여 내부 열재순환 효과를 규명하고 예열용 다공성 블럭(preheating porous block)과 복사 차폐용 다공성 블럭(radiative insulating porous block)의 효 과에 대한 연구와 초희박 혼합기나 저 발열량 연료의 연소 가능성을 제시하고 수치 계 산에 필요한 자료를 제시하는 것이다.

• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1329-1337
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• 2005

The OLED (Organic Light Emitting Diodes) display recently used for the information indicating device has many advantages over the LCD (Liquid Crystal Display), and its demand will be increased highly. The linear cell should be designed carefully considering the uniformity of thin film on the substrate. Its design needs to compute the temperature field analytically because the uniformity for the thin film thickness depends on the temperature distribution of the source (organic material). In the present study, the design of the linear cell will be modified or improved on the basis of the temperature profiles obtained for the simplified linear cell. The temperature distributions are numerically calculated through the STAR-CD program, and the grids are generated by means of the ICEM CFD program. As the results of the simplified linear cell, the temperature deviation was shown in the parabolic form among the both ends and the center of the source. In order to reduce the temperature deviation, the configuration of the rectangular ends of the crucible was modified to the circular type. In consequence, the uniform temperature is maintained in the range of about 90 percent length of the source. It is expected that the present methods and results on the temperature analysis can be very useful to manufacture the vapor deposition device.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2010년도 추계학술발표회 자료집
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• pp.144-147
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• 2010

방화선 구축 작업은 산불확산이 진행되고 있는 화선으로부터 확산진행방향의 연소물질을 제거하여 화염이 확산되지 않도록 하는 대표적인 간접진화 방법이다. 하지만 방화선 구축 폭에 대한 기준은 산불진화 경험을 통해 약 0.5~1.5m폭으로 작업하는 것으로 알려져 있고 열전달 수치해석 및 실험 등을 통해 아직 구명된 바 없다. 이에 본 연구에서는 소나무 낙엽층을 대상으로 풍속 0~5m/s, 경사 $0{\sim}50^{\circ}$의 조건에 대해 복사열전달 수치해석을 이용하여 방화선 구축 폭을 산정하였다. 그 결과, 복사열유속에 의한 낙엽의 발화가 발생하지 않는 거리는 각 조건별 평균화염높이에 대해서는 0.35~0.65m, 최대화염높이에 대해서는 0.75~1.05m로 산정되었다. 따라서 안전율을 고려한 적정 방화선 구축 폭은 최대화염높이를 적용한 1.05m가 적합할 것으로 판단되며 향후, 실험 및 현장사례조사를 통한 적정 방화선 구축 폭에 대한 비교분석 연구가 추가적으로 필요할 것으로 판단된다.