• Korean Journal of Remote Sensing
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• v.26 no.2
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• pp.251-262
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• 2010

In order to provide quantitative control of the standard products of Geostationary Ocean Color Imager (GOCI), on-board radiometric correction, atmospheric correction, and bio-optical algorithm are obtained continuously by comprehensive and consistent calibration and validation procedures. The calibration/validation for radiometric, atmospheric, and bio-optical data of GOCI uses temperature, salinity, ocean optics, fluorescence, and turbidity data sets from buoy and platform systems, and periodic oceanic environmental data. For calibration and validation of GOCI, we compared radiometric data between in-situ measurement and HyperSAS data installed in the Ieodo ocean research station, and between HyperSAS and SeaWiFS radiance. HyperSAS data were slightly different in in-situ radiance and irradiance, but they did not have spectral shift in absorption bands. Although all radiance bands measured between HyperSAS and SeaWiFS had an average 25% error, the 11% absolute error was relatively lower when atmospheric correction bands were omitted. This error is related to the SeaWiFS standard atmospheric correction process. We have to consider and improve this error rate for calibration and validation of GOCI. A reference target site around Dokdo Island was used for studying calibration and validation of GOCI. In-situ ocean- and bio-optical data were collected during August and October, 2009. Reflectance spectra around Dokdo Island showed optical characteristic of Case-1 Water. Absorption spectra of chlorophyll, suspended matter, and dissolved organic matter also showed their spectral characteristics. MODIS Aqua-derived chlorophyll-a concentration was well correlated with in-situ fluorometer value, which installed in Dokdo buoy. As we strive to solv the problems of radiometric, atmospheric, and bio-optical correction, it is important to be able to progress and improve the future quality of calibration and validation of GOCI.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.205-209
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• 2003

The urbanization of Korea has been rapidly progressed since 1960. Current available satellite images used in various fields are obtained after 1975. The CORONA Image data declassified in 1995, and are the only source of image which provide 1960's topographic information of the Korean Peninsula. In this sense CORONA imagery can be readily applicable for change detection in various fields such as urban, forest and environmental planning. To generate CORONA mosaic image of Korea we undertook comparative analysis of the various geocoding methods. We also applied the linear regression method to perform the radiometric balance between the strips.

• Korean Journal of Remote Sensing
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• v.27 no.6
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• pp.693-701
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• 2011

Image registration is an essential process to analyze the time series of satellite images for the purpose of image fusion and change detection. The Mutual Information (MI) is commonly used as similarity measure for image registration because of its robustness to noise. Due to the radiometric differences, it is not easy to apply MI to multi-temporal satellite images using directly the pixel intensity. Image features for MI are more abundantly obtained by employing a Gabor filter which varies adaptively with the filter characteristics such as filter size, frequency and orientation for each pixel. In this paper we employed Bidirectional Gabor Filter Energy (BGFE) defined by Gabor filter features and applied the BGFE to similarity measure calculation as an image feature for MI. The experiment results show that the proposed method is more robust than the conventional MI method combined with intensity or gradient magnitude.

• Korean Journal of Remote Sensing
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• v.14 no.1
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• pp.95-101
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• 1998

This paper describes an algorithm which was developed for removing along-track and across-track striping effect shown in JERS-1 OPS/VNIR images. A statistical algorithm was implemented based on the mean brightness value of each along-track and across-track line. Different from any filtering techniques in either spatial or frequency domain, the developed algorithm does not change the radiometric characteristics of image pixels. The algorithm will be inserted to the JERS-1 OPS image data processing chain in the Satellite Technology Research Center direct receiving station.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.5
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• pp.383-392
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• 2007

This study focuses on co-registration and band selection, which are one of the pre-processing steps to apply the change detection technique using hyperspectral images. We carried out automatic co-registration by using the SIFT algorithm which performance was already established in the computer vision fields, and selected the bands fur change detection by estimating the noise of image through the PIFs reflecting the radiometric consistency. The EM algorithm was also applied to select the band objectively. Hyperion images were used for the proposed techniques, and non-calibrated bands and striping noises contained in Hyperion image were removed. Throughout the results, we could develop the reliable co-registration procedure which coincided with accuracy within 0.2 pixels (RMSE) for change detection, and verified that band selection depending on the visual inspection could be objective by extracting the PIFs.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.3
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• pp.13-20
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• 2009

Techniques for change detection using satellite images enable efficient detection of natural and artificial changes in use of land through multi-phase images. As for change detection, different results are made based on methods of calibration of satellite images, types of input data, and techniques in change analysis. Thus, an analytic technique that is appropriate to objectives of a study shall be applied as results are different based on diverse conditions even when an identical satellite and an identical image are used for change detection. In this study, Normalized Difference Vegetation Index (NDVI) and Principal Component Analysis (PCA) were conducted after geometric calibration of satellite images which went through absolute and relative radiometric calibrations and change detection analysis was conducted using Image Difference (ID) and Image Rationing (IR). As a result, ID-NDVI showed excellent accuracy in change detection related to vegetation. ID-PCA showed 90% of accuracy in all areas. IR-NDVI had 90% of accuracy while it was 70% and below as for paddies and dry fields${\rightarrow}$grassland. IR-PCA had excellent change detection over all areas.

• Economic and Environmental Geology
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• v.29 no.2
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• pp.119-127
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• 1996

Electrum-sulfide minerals of the Namsan Au-Ag mine were deposited in two stages of quartz and calcite veins that fill fault planes in Mesozoic granitic rocks (230~155 Ma). The K/Ar radiometric dating of hydrothermal sericite indicates that mineralization is early Cretaceous age ($127{\pm}3.0Ma$). Mineralogic, fluid inclusion and sulfur isotopic data show that ore minerals were deposited at temperatures between $340^{\circ}C$ and $200^{\circ}C$ from fluid with salinities of 3 to 6 equiv. wt % NaCl. Evidence of fluid boiling (and $CO_2$ effervescence) indicates a maximum pressures of 100 bars. The formation temperature and $fs_2$, of Au-mineralization from the Namsan mines are mainly $280{\sim}230^{\circ}C$ and $10^{-11}{\sim}10^{-13}$ atm, respectively. Au deposition was likely a result of boiling caused to chemical change (pH, $f_{O2}$, ${\Sigma}_{H_2S{\cdot}{\cdot}}$) of ore-fluids. Sulfur isotope composition of sulfide minerals (${\delta}^{34}S=5.1$ to 8.2‰) are consistent with ${\delta}^{34}S_{{\Sigma}{H2S}}$ value of +6 to +7‰, suggesting an igneous source of sulfur partially mixed with wall-rock sulfur.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.3983-3991
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• 2013

Census transform is one of the stereo vision methods which is robust to radiometric distortion and illuminance change. This paper proposes a hybrid census transform using the mini census transform and the generalized census transform concurrently. This method uses simplicity of mini census transform and noise feature of generalized census transform together. This paper performed stereo matching containing post processing to evaluate each methods. The result shows that hybrid census transform has similar performance to generalized census transform and mean value of calculation complexity between mini census transform and generalized census transform.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.152-152
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• 2019

This study demonstrates a novel approach of remotely sensed estimates of stream flow at fifteen hydrological station in the Han River Basin, Korea. Multi-temporal data of the European Space Agency's Sentinel-1 SAR satellite from 19 January, 2015 to 25 August, 2018 is used to develop and validate the flow estimation model for each station. The flow estimation model is based on a power law relationship established between the remotely sensed surface area of water at a selected reach of the stream and the observed discharge. The satellite images were pre-processed for thermal noise, radiometric, speckle and terrain correction. The difference in SAR image brightness caused by the differences in SAR satellite look angle and atmospheric condition are corrected using the histogram matching technique. Selective area filtering is applied to identify the extent of the selected stream reach where the change in water surface area is highly sensitive to the change in stream discharge. Following this, an iterative procedure called the Optimum Threshold Classification Algorithm (OTC) is applied to the multi-temporal selective areas to extract a series of water surface areas. It is observed that the extracted water surface area and the stream discharge are related by the power law equation. A strong correlation coefficient ranging from 0.68 to 0.98 (mean=0.89) was observed for thirteen hydrological stations, while at two stations the relationship was highly affected by the hydraulic structures such as dam. It is further identified that the availability of remotely sensed data for a range of discharge conditions and the geometric properties of the selected stream reach such as the stream width and side slope influence the accuracy of the flow estimation model.

• Korean Journal of Remote Sensing
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• v.26 no.2
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• pp.157-165
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• 2010

In June 2010, Geostationary Ocean Color Imager (GOCI), the world's first ocean color observation satellite will be launched. GOCI is planned for use in real-time monitoring of the ocean environment around Korean Peninsula by daily analysis of ocean environment measurements of chlorophyll concentration, dissolved organic matter, and suspended sediments taken eight times per day for seven years. GOCI primary data will support a fishery information service and red tide forecasting, and ocean climate change research. In this paper, the development background of GOCI, user requirements, GOCI architecture, and the GOCI on-orbit operational concept are explained.