• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.173-176
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• 2002

This report summarizes the results of MODTRAN model that are used for the calculation of input radiance of the KOMPSAT-2 Multispectral Camera (MSC). We have calculated the input radiances for four months: January 15, April 15, July 15 and October 15. Annual averages are the arithmetic mean of results from four months. We used the mid-latitude winter and summer for the month of January and July, respectively, while US standard atmospheres are used for April and October. The orbital characteristics of KOMPSAT-2 and the seasonal variations of solar zenith angle over the Korean peninsula were incorporated as inputs to the model. The tropospheric aerosol extinction (visibility = 50 km) was assumed. The surface albedo used in the model calculation represents the global annual mean clear-sky albedo. MSC contract values are found to be considerably greater in the MSC spectral range than the total radiances calculated with the above general conditions. From these results, it can be inferred that the forthcoming MSC images would be somewhat dark. We certainly need a countermeasure for this issue.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.19-25
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• 2019

The CleanSYS(Clean SYStem) is operated to monitor air pollutants emitted from specific industrial complexes in Korea. So the industrial complexes without the system are directly monitored by the control officers. For efficient monitoring, studies using various sensors have been conducted to monitor air pollutants emitted from industrial complex. In this study, hyperspectral sensors were used to model and verify the equations for estimating the concentration of $NO_2$(nitrogen dioxide) in air pollutants emitted. For development of the equations, spectral radiance were observed for $NO_2$ at various concentrations with different SZA(Solar Zenith Angle), VZA(Viewing Zenith Angle), and RAA(Relative Azimuth Angle). From the observed spectral radiance, the calculated value of the difference between the values of the specific wavelengths was taken as an absorption depth, and the equations were developed using the relationship between the depth and the $NO_2$ concentration. The spectral radiance mixed gas of $NO_2$ and $SO_2$(sulfur dioxide) was used to verify the equations. As a result, the $R^2$(coefficient of determination) and RMSE(Root Mean Square Error) were different from 0.71~0.88 and 72~23 ppm according to the form of the equation, and $R^2$ of the exponential form was the highest among the equations. Depending on the type of the equations, the accuracy of the estimated concentration with varying concentrations is not constant. However, if the equations are advanced in the future, hyperspectral sensors can be used to monitor the $NO_2$ emitted from the industrial complex.

• Korean Journal of Remote Sensing
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• v.30 no.1
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• pp.47-59
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• 2014

Volcanic ash (VA) can be estimated by remote sensing sensors through their spectral signatures determined by the inherent optical property (IOP) including complex refractive index and the scattering properties. Until now, a very limited range of VA refractive indices has been reported and the VA from each volcanic eruption has a different composition. To improve the robustness of VA remote sensing, there is a need to understanding of VA - radiation interactions. In this study, we calculated extinction coefficient, scattering phase function, asymmetry factor, and single scattering albedo which show different values between andesite and pumice. Then, IOPs were used to analyze the relationship between theoretical remote sensed radiation calculated by radiative transfer model under various aerosol optical thickness (${\tau}$) and sun-sensor geometries and characteristics of VA. It was found that the mean rate of change of radiance at top of atmosphere versus ${\tau}$ is six times larger than in radiance values at 0.55 ${\mu}m$. At the surface, positive correlation dominates when ${\tau}$ <1, but negative correlation dominates when ${\tau}$ >1. However, radiance differences between andesite and pumice at 11 ${\mu}m$ are very small. These differences between two VA types are expressed as the polynomial regression functions and that increase as VA optical thickness increases. Finally, these results would allow VA to be better characterized by remote sensing sensors.

• Korean Journal of Remote Sensing
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• v.28 no.5
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• pp.531-548
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• 2012

To identify Cochlodinium polykrikoides red tide from non-red tide water (satellite high chlorophyll waters) in the South Sea of Korea (SSK), we improved a spectral classification method proposed by Son et al.(2011) for the world first Geostationary Ocean Color Imager (GOCI). C. polykrikoides blooms and non-red tide waters were classified based on four different criteria. The first step revealed that the radiance peaks of potential red tide water occurred at 555 and 680 nm (fluorescence peak). The second step separated optically different waters that were influenced by relatively low and high contributions of colored dissolved organic matter (CDOM) (including detritus) to chlorophyll. The third and fourth steps discriminated red tide water from non-red tide water based on the blue-to-green ratio, respectively. After applying the red tide classification, the spectral response of C. polykrikoides red tide water, which is influenced by pigment concentration as well as CDOM (detritus), showed different slopes for the blue and green bands (lower slope at blue bands and higher slope at green bands). The opposite result was found for non-red tide water. This modified spectral classification method for GOCI led to increase user accuracy for C. polykrikoides and non-red tide blooms and provided a more reliable and robust identification of red tides over a wide range of oceanic environments than was possible using chlorophyll a concentration, or proposed red tide detection algorithms. Maps of C. polykrikoides red tide in SSK outlined patches of red tide covering the area near Naro-do and Tongyeong during the end of July and early of August, 2012 and extending into from Wan-do and Geoje-do during the middle of August, 2012.

• Korean Journal of Remote Sensing
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• v.17 no.3
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• pp.211-218
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• 2001

We have performed the calculation of total radiances for the KOMPSAT-2 Multispectral Camera (MSC) using a radiative transfer model of MODTRAN and examined its results. To simulate four seasonal conditions in the model calculation, we used model atmospheres of mid-latitude winter and summer for calculations of January 15 and July 15, and US standard for April 15 and October 15, respectively. Orbital parameters of KOMPSAT-2 and the seasonal solar zenith angles were taken into account. We assumed that the meteorological range is the tropospheric aerosol extinction of 50 km and surface albedo is the global average of clear-sky albedo of 0.135. MSC contract values are found to be considerably greater in the MSC spectral range than the total radiances calculated with the above general conditions. It is also shown that the spectral behavior of model results with the constant surface albedo differs from the pattern of MSC contract values. From these results, it can be inferred that the forthcoming MSC images would be somewhat dark.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.266-274
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• 2023

Recently, sterilization technology has received increasing interest due to the COVID-19 pandemic and required safety precautions. Particularly, sterilization devices using near ultraviolet (UV) with a 405 nm wavelength are also drawing attention. It has a UV-C wavelength and other sterilization effects. Its blue-colored light on the boundary between UV and visible light is used as a light-emitting diode (LED) lamp for 405 nm sterilization, owing to its longer wavelengths than UV rays. However, the 405 nm wavelength contains blue light that can damage the eyes and skin during prolonged exposures and affect the emotional and biological parts of the body. Currently, 405 nm sterilization LED light registers are circulating in the market. However, they have not undergone safety tests for blue-light hazards. Thus, with the active distribution of sterilization LED lights, solid safety standards and management systems are essential to protect users from blue-light hazards. Accordingly, in this study, we conducted spectral radiance and spectral radiative luminance tests on 405 nm sterilization LED registers available in the market by the measurement criteria of IEC 62471. Safety standards must be established to secure users' safety against blue light hazards at a time when 405nm sterilization LED lights are actively distributed due to COVID-19.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.1 s.151
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• pp.40-47
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• 2007

This study is focused on developing a software that predicts the temperature distribution and infrared Emission from 30 objects considering the solar radiation through the atmosphere. The solar radiation through the atmosphere is modeled by using the well-known LOWTRAN7 code. Surface temperature information is essential for generating the infrared scene of the object. Predictions of the transient surface temperature and the infrared emission from a naval ship by using the software developed here show fairly good results by representing the typical temperature and emitted radiance distributions expected for the naval ship considered in mid latitude. Emissivity of each material is appeared to be an important parameter for recognizing the target in Infrared band region. The numerical results also show that the low emissivity surface on the heat source can be helpful in reducing the IR image contrast as compared to the background sea.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.569-572
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• 2002

Terra MODIS is one of the few space-borne sensors currently capable of acquiring radiometric data over the range of view angles. Institute of Industrial Science, University of Tokyo, has been receiving Terra MODIS data at Tokyo since May 2001 and Asian Institute of Technology at Bangkok since May 2001. They can cover whole East Asia and is expected to monitor environmental changes regularly such as deforestation, forest fires, floods and typhoon. Over eight hundred scenes have been archived in the storage system and they occupy 2 TB of disk space so far. In this study, MODIS data processing system on WWW is developed including following functions: spectral subset (250m, 500m, 1000m channels), radiometric correction to radiance, spatial subset of geocoded data as a rectangular area with latitude-longitude grid system in HDF format, generation of a quick look file in JPEG format. Users will be notified just after all the process have finished via e-mail. Using this system enables us to process MODIS data on WWW with a few input parameters and download the processed data by FTP access. An easy to use interface is expected to promote the use of MODIS data. This system is available via the Internet on the following URL from September 1 2002, "http : //webmodis.iis.u-tokyo.ac.jp/".

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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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.

• Journal of the Korean earth science society
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• v.26 no.2
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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.