• Korean Journal of Remote Sensing
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• v.13 no.1
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• pp.57-73
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• 1997

This paper is related to the correction of radiometric distortions induced by topographic relief. RADARSAT SAR image data were obtained over the mountainous area near southern part of Seoul. Initially, the SAR data was geometrically corrected and registered to plane rectangular coordinates so that each pixel of the SAR image has known topographic parameters. The topographic parameters (slope and aspect) at each pixel position were calculated from the digital elevation model (DEM) data having a comparable spatial resolution with the SAR data. Local incidence angle between the incoming microwave and the surface normal to terrain slope was selected as a primary geometric factor to analyze and to correct the radiometric distortions. Using digital maps of forest stands, several fields of rather homogeneous forest stands were delineated over the SAR image. Once the effects of local incidence angle on the radar backscatter were defined, the radiometric correction was performed by an empirical fuction that was derived from the relationship between the geometric parameters and mean radar backscatter. The correction effects were examined by ground truth data.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.6_1
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• pp.519-528
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• 2012

It was pointed out that the terrain distortion of SAR image is even worse than that of optical image although SAR imagery has the advantages of being independent of solar illumination and weather conditions. It is thus necessary to correct terrain distortion in SAR image for various application areas to integrate SAR and optical image information. There has to be a clear evaluation of terrain correction of high resolution SAR image according to the quality of DEM because the DEM of study site is generally used in the process of terrain correction. To achieve this issue, this paper compared the effects of quality of Digital Elevation Model(DEM) in the process of terrain correction of high resolution SAR images, using the DEM produced from 1:5000 topographic contour maps, LiDAR DEM, ASTER GDEM, SRTM DEM. We used TerraSAR-X and Cosmo-SkyMed, as the test data set, which are constructed on the same X-band SAR system as KOMPSAT-5. In order to evaluate quantitatively the correction results, we conducted comparative evaluation with the KOMPSAT-2 ortho image of the same region. The evaluation results showed that the DEM produced from 1:5000 topographic contour maps achieved successful results in the terrain correction of SAR image compared with the other DEM data, and the widely used SRTM DEM data in various applications was not suitable for the terrain correction of high resolution SAR images.

• Journal of Information Processing Systems
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• v.11 no.1
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• pp.134-147
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• 2015

This paper presents the applications of Kriging spatial interpolation methods for meteorologic variables, including temperature and relative humidity, in regions of Vietnam. Three types of interpolation methods are used, which are as follows: Ordinary Kriging, Universal Kriging, and Universal Kriging plus Digital Elevation model correction. The input meteorologic data was collected from 98 ground weather stations throughout Vietnam and the outputs were interpolated temperature and relative humidity gridded fields, along with their error maps. The experimental results showed that Universal Kriging plus the digital elevation model correction method outperformed the two other methods when applied to temperature. The interpolation effectiveness of Ordinary Kriging and Universal Kriging were almost the same when applied to both temperature and relative humidity.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.165-168
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• 2010

This paper describes the results of complete Bouguer anomalies computed from the Free-air anomalies that derived from Sandwell and DNSC08 mairne gravity models. Complete bouguer corrections consist of three parts: the bouguer correction (Bullard A), the curvature correction (Bullard B) and the terrain correction (Bullard C). These all corrections have been computed over the East Sea on a $1'{\times}1'$ elevation data (topography and bathymetry) derived from ETOPO1 global relief model. In addition, a constant topographic (sea-water) density of $2,670kg/m^3$ ($1,030kg/m^3$) has been used for all correction terms. The distribution of complete bouguer anomalies computed from DNSC08 are -34.390 ~ 267.925 mGal, and those from Sandwell are -32.446 ~ 266.967 mGal in East Sea. The mean and RMSE value of the difference between DNSC08 and Sandwell is $0.036{\pm}2.373$ mGal. The highest value of complete bouguer anomaly are found around the region of $42{\sim}43^{\circ}N$ and $137{\sim}139^{\circ}E$ (has the lowest bathymetry) in both models. Theses values show that the gravity distribution of both models, DNSC08 and Sandwell, are very similar. They indicate that satellite-based marine gravity model can be effectively used to analyze the geophysical, geological and geodetic characteristics in East Sea.

• Atmosphere
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• v.27 no.3
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• pp.331-344
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• 2017

Solar energy is calculated using high-resolution digital elevation model (DEM). In focus on Seoul metropolitan area, correction coefficients of direct and diffuse solar energy with the topographic effect are calculated from DEM with 1720, 900, 450, 90 and 30 spatial resolutions ($m{\times}m$), respectively. The solar energy on the real surface with high-resolution is corrected using by the correction coefficients with topographic effect from the solar energy on horizontal surface with lower resolution. Consequently, the solar energy on the real surface is more detailed distribution than those of horizontal surface. In particular, the topographic effect in the winter is larger than summer because of larger solar zenith angle in winter. In Seoul metropolitan area, the monthly mean topographic effects are more than 200% in winter and within 40% in summer. And annual topographic effects are negative role with more than -60% and positive role with below 40%, respectively. As a result, topographic effect on real surface is not a negligible factor when calculating and analyzing solar energy using regional and global models.

• Journal of the Korea Society of Computer and Information
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• v.16 no.8
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• pp.129-135
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• 2011

In this paper, we propose a multi target's elevation angle estimation method using multi beam forming technique. This method make a stacked beam to digital processing a received signal in array element. There can be desired receiving beam to application weight value at antenna element in beam forming. Currently, we are to make multi stacked beam using fast fourier transform in stead of phase shifter to be a computer performance much improvement. Also, we improve multi beam directivity using beam steering error correction technique in order to beam steering to desired direction in receiver. Through simulation, we show that the proposed elevation estimation method based on fast fourier transform and beam steering error correction technique, improves th performance of target estimation compared to previous method.

• Journal of the Korean Association of Geographic Information Studies
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• v.2 no.3
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• pp.91-100
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• 1999

To extract value-added products from satellite images for the benefit of science and human life, the Satellite Technology Research Center at Korea Advanced Institute of Science and Technology has developed an integrated software 'Valadd-Pro'. In this paper, the 'Valadd-Pro' software is briefly introduced and its main components such as geometric correction, ortho correction and digital elevation model extraction are described. The performances of the 'Valadd-Pro' was assessed on $60km{\times}60km$ SPOT panchromatic images using ground control points from GPS measurements. Also, the height accuracy was measured by comparing our results with the $DTEDs^3$ produced by USGS and the DEM generated from the digitized countours of maps produced by the National Geographic Institute. In geometric correction, the 'Valadd-Pro' software needed fewer ground control points than a commercial software 'P' for the satisfactory results. In ortho correction, the 'Valadd-Pro' software show the similar performance to a commercial software 'P'. In digital elevation model extraction, the 'Valadd-Pro' software is two times more accurate and four times faster than a commercial software 'P'.

• Archives of Plastic Surgery
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• v.33 no.2
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• pp.135-143
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• 2006

The characteristics of the cleft lip nasal deformity is defined in this article in three planes. The alar flaring is explained in X axis, the lower positioning of the alar free margin is imagined in Y axis and the short hemicolumella is in Z axis. Most cleft surgeons have focused on the malposition of the lateral crus of alar cartilage while the author defined it in X and Y axises and tried to correct that deformity of short hemicolumella in Z axis. For the last 13 years the author applied that method in 818 cases of secondary cleft lip nose deformity. Through the columellar splitting incision extended to free margin of the alar not beyond the nasal dorsum, the skin and soft tissue of the webbing deformed the nasal tip was excised in crescent fashion. The dissected short hemicolumella including the medial crus was thus elevated and advanced into the space of the deformed nasal tip after the crescent excision. This procedure should be followed by the correction of the deformities in X and Y axis. The medial crus elevation is more effective and critical way to have the constant and nice outcome than the lateral crus reposition in secondary cleft lip nasal deformity

• Journal of The Korean Astronomical Society
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• v.22 no.2
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• pp.141-160
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• 1989

In order to derive time dependence of the atmospheric diffuse light, which consists of the airglow continuum emission and diffusely scattered radiations of the intergrated starlight, the diffuse Galactic light, and the zodiacal light, we have analyzed the meridian scan observations of the sky brightness at $5,080\;{\AA}$ and $5,300\;{\AA}$. Amplitude of the time-variation becomes larger for lower elevation, and maximum amplitude is found to be about $50\;S_{10}(V)_{G2V}$ at elevation $10^{\circ}$. The atmospheric diffuse radiation attains maximum brightness at around midnight, and afterward it decreases slowly with time. The time-variations for the two wavelengths are similar to each other. The observed brightness distribution of the diffuse light along the zenith distance is fitted to an empirical relation of two parameters. By making the two parameters time-dependent, we describe the spatial and time variations of the atmospheric diffuse light. This enables us to make time dependent correction for the atmospheric diffuse component in the reduction of zodiacal light brightness.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.1
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• pp.35-40
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• 2011

While high-definition precipitation maps with a 270 m spatial resolution are available for South Korea, there is little information on geospatial availability of precipitation water for the famine - plagued North Korea. The restricted data access and sparse observations prohibit application of the widely used PRISM (Parameter-elevation Regressions on Independent Slopes Model) to North Korea for fine-resolution mapping of precipitation. A hybrid method which complements the PRISM grid with a sub-grid scale elevation function is suggested to estimate precipitation for remote areas with little data such as North Korea. The fine scale elevation - precipitation regressions for four sloping aspects were derived from 546 observation points in South Korea. A 'virtual' elevation surface at a 270 m grid spacing was generated by inverse distance weighed averaging of the station elevations of 78 KMA (Korea Meteorological Administration) synoptic stations. A 'real' elevation surface made up from both 78 synoptic and 468 automated weather stations (AWS) was also generated and subtracted from the virtual surface to get elevation difference at each point. The same procedure was done for monthly precipitation to get the precipitation difference at each point. A regression analysis was applied to derive the aspect - specific coefficient of precipitation change with a unit increase in elevation. The elevation difference between 'virtual' and 'real' surface was calculated for each 270m grid points across North Korea and the regression coefficients were applied to obtain the precipitation corrections for the PRISM grid. The correction terms are now added to the PRISM generated low resolution (~2.4 km) precipitation map to produce the 270 m high resolution map compatible with those available for South Korea. According to the final product, the spatial average precipitation for entire territory of North Korea is 1,196 mm for a climatological normal year (1971-2000) with standard deviation of 298 mm.