• Korean Journal of Remote Sensing
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• v.31 no.2
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• pp.111-125
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• 2015

In this study, the target detection using both high-resolution satellite SAR and Elecro-Optical (EO) images such as TerraSAR-X and WorldView-2 is performed, considering the characteristics of targets. The targets of our interest are featured by being stationary and appearing as cluster targets. After the target detection of SAR image by using Constant False Alarm Rate (CFAR) algorithm, a series of processes is performed in order to reduce false alarms, including pixel clustering, network clustering and coherence analysis. We extend further our algorithm by adopting the fast and effective ellipse detection in EO image using randomized hough transform, which is significantly reducing the number of false alarms. The performance of proposed algorithm has been tested and analyzed on TerraSAR-X SAR and WordView-2 EO images. As a result, the average false alarm for group of targets is 1.8 groups/$64km^2$ and the false alarms of single target range from 0.03 to 0.3 targets/$km^2$. The results show that groups of targets are successfully identified with very low false alarms.

• Korean Journal of Remote Sensing
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• v.31 no.2
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• pp.101-110
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• 2015

Synthetic Aperture Radar Interferometry (InSAR) is affected by various noise source such as atmospheric artifact, orbital error, processing noise etc.. Especially, one of the dominant noise source for long-wave SAR system, such as ALOS PALSAR (L-band SAR satellite) is the ionosphere effect because phase delays on radar pulse through the ionosphere are proportional to the radar wavelength. To avoid misinterpret of phase signal in the interferogram, it is necessary to detect and correct ionospheric errors. Recently, a MAI (Multipler Aperture SAR Interferometry) based ionospheric correction method has been proposed and considered one of the effective method to reduce phase errors by ionospheric effect. In this paper, we introduce the MAI-based method for ionospheric correction. Moreover we propose an efficient method that apply the method over non-coherent area using directional filter. Finally, we apply the proposed method to the ALOS PALSAR pairs, which include the west sea coast region in Korea. A polynomial fitting method, which is frequently adopted in InSAR processing, has been applied for the mitigation of phase distortion by the orbital error. However, the interferogram still has low frequency of Sin pattern along the azimuth direction. In contrast, after we applied the proposed method for ionospheric correction, the low frequency pattern is mitigated and the profile results has stable phase variation values within ${\pm}1rad$. Our results show that this method provides a promising way to correct orbital and ionospheric artifact and would be important technique to improve the accuracy and the availability for L-band or P-band systems.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1650-1654
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• 2007

홍수와 가뭄의 증가, 수질악화, 물부족 등 물 문제 해결을 위한 대안으로 통합수자원관리에 대한 논의가 국제사회에서 활발하게 진행되고 있다. 국내에서도 많은 학자들이 수자원관리를 위한 새로운 대안으로 통합수자원관리를 주장하고 있지만, 추상적인 설명이 대부분이다. 따라서 본 연구는 통합수자원관리에 대한 정의, 원칙, 추진전략 등을 정리하여 통합수자원관리에 대한 종합적이고 체계적인 정보를 제공하고자 한다. 본 연구는 다음과 같은 흐름을 갖는다. 첫째, 수자원관리를 위한 새로운 대안으로 통합수자원관리가 등장하게 된 배경을 살펴보았다. 물문제를 해결하기 위해서는 연속적이고 상호작용하는 하나의 '시스템(係)'으로 수자원을 인식하고 관리해야 한다는 주장이 확산되고 있으며, 통합수자원관리가 그러한 인식을 갖고 있는 대안으로 등장하였다. 둘째, 통합수자원관리의 정의, 원칙 등을 조사하였다. 통합수자원관리는 자연의 지속가능성을 훼손하지 않으면서 경제적, 사회적 복지를 최대화하기 위하여 물, 토지 및 관련 자원의 조화로운 개발을 위한 과정으로 정의된다. 이러한 통합수자원관리를 위한 원칙으로는 지속가능한 수자원의 개발, 이용 및 관리원칙, 물순환 체계 고려 및 유역관리원칙, 이해당사자 참여 및 조정의 원칙, 비용부담 및 편익 균형배분의 원칙 등이 있다. 셋째, 통합수자원관리를 위한 추진방안을 제시하였다. 법제도 정비 및 부문별 통합관리강화, 수자원 관련 자료의 신뢰도 제고 및 의사결정 체계 구축, 관련계획과의 연계, 계획-실행-평가의 순환구축, 물관리 비용부담체계 구축 등이 통합수자원관리의 실행을 앞당길 수 있을 것이다. 본 연구는 통합수자원관리에 대하여 종합적인 정보를 제공하고 개선을 위한 추진방안을 제시하여 국내 수자원관리의 문제해결을 위한 기반을 구축하는 데에 기여할 것으로 기대된다. 범람범위의 1차적인 정보에서 수립할 수 있었던 계획이 가질 수 있었던 한계점을 좀 더 향상된 정보를 이용하여 극복함으로써 효율적이고 체계적인 치수 방재 계획수립이 가능할 것으로 판단된다.group) 67개, 속(family) 161개로 분류되었으며, 가장 저차단위인 통(series)이 390개 분류되었다. 또한 작물이용측면에서 실용적 분류를 실시하였는데, 논토양의 경우 보통논, 미숙논, 사질논, 습논, 염해논, 특이산성논으로 분류할 경우 각각의 분포면적이 31.9%, 23.0%, 31.9%, 9.1%, 3.9%, 0.2%이었다. 밭토양의 경우에도 보통밭, 사질밭, 미숙밭, 중점밭, 고원밭, 화산회밭으로 6개 유형으로 분류할 경우 각각의 분포면적은 41.9%, 23.3%, 17.5%, 13.9%, 1.1. 2.2% 이었다. 도시화 및 도로확대 등 다양한 토지이용 및 지형개변으로 과거의 토양정보가 많이 변경되었다. 그래서, 앞으로는 인공위성자료 및 항공사진을 이용하여 빠르고 쉽게 활용할 수 있는 토양조사 방법개발과 기 구축된 토양도의 수정, 보완 작업이 필요한 절실히 요구되고 있는 현실이다.브로 출시에 따른 마케팅 및 고객관리와 관련된 시사점을 논의한다.는 교합면에서 2, 3, 4군이 1군에 비해 변연적합도가 높았으며 (p < 0.05), 인접면과 치은면에서는 군간 유의차를 보이지 않았다 이번 연구를 통하여 복합레진을 간헐적 광중합시킴으로써 변연적합도가 향상될 수 있음을 알 수 있었다.시장에 비해 주가가 비교적 안정적인 수준을 유지해 왔다고 볼 수 있다.36.4%)와 외식을 선호(29.1%)${\lrcorner}$ 하기 때문에 패스트푸드를 이용하게 된 것으로 응답 하였으며, 남 여 대학생간에는 유의한 차이(p<0.05)가 인정되었다. 응답자의 체형은 ${\

• 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.

• Economic and Environmental Geology
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• v.42 no.4
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• pp.343-356
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• 2009

SCS method was applied to make the assessments of direct runoff according to land use changes in Jeju island. Land uses were obtained from 5 year-period remote sensing time series data from 1975 to 2000 which are provided by Water Management Information System (WAMIS). Hydrologic soil groups were categorized based on soil series of National Academy of Agricultural Sciences (NAAS), and permeable geologic structures such as Sumgol, Gotzawal and so on. The land uses of Jeju island are obviously characterized by urban-agricultural areas increases, and forest areas decrease. According to land use changes, curve number (CN) for Jeju island was consistently increased from 65.3 in 1975 to 69.6 in 2000. From 1975 to 2000, the amount of direct runoff and ratios increased due to CN changes. When the rainfall data in 1995 was applied to each year, the direct runoff amounts were $299.0{\sim}351.6\;mm$, and runoff ratios were $15.1{\sim}17.7%$. In the case of the application of the rainfall data in 2000, the direct runoff amounts were $136.9{\sim}161.5\;mm$, and runoff ratios were $9.7{\sim}11.5%$. Since direct runoff can be closely related to groundwater recharge and sustainable groundwater yield, the groundwater influence caused by land use changes or district exploitations should be considered for the reasonable water management and development in Jeju island.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.2
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• pp.3-12
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• 2010

In previous studies, the digital measurement systems and analysis algorithms were developed by using the related techniques, such as the aerial photograph detection and high resolution satellite image process. However, these studies were limited in 2-dimensional geo-processing. Therefore, it is necessary to apply the 3-dimensional spatial information and coordinate system for higher accuracy in recognizing and locating of geo-features. The objective of this study was to develop a stochastic algorithm for the optimal sensor placement using the 3-dimensional spatial analysis method. The 3-dimensional information of the LiDAR was applied in the sensor field algorithm based on 2- and/or 3-dimensional gridded points. This study was conducted with three case studies using the optimal sensor placement algorithms; the first case was based on 2-dimensional space without obstacles(2D-non obstacles), the second case was based on 2-dimensional space with obstacles(2D-obstacles), and lastly, the third case was based on 3-dimensional space with obstacles(3D-obstacles). Finally, this study suggested the methodology for the optimal sensor placement - especially, for ground-settled sensors - using the LiDAR data, and it showed the possibility of algorithm application in the information collection using sensors.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.11
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• pp.984-997
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• 2015

Chang'e-3 consisting of a lunar lander and exploration rover was launched on December 1, 2013 aboard a Long March 3B rocket flying from Xichang space launch center. Chang'e-3 was inserted into the lunar orbit after about a 5-day transit to the Moon and landed on the targeted landing site after orbiting around the Moon for 8 days. The successful landing of the Chang'e-3 gives a lot of help to analyze the future needs of the subsystem technologies and to figure out the trajectory from launch to lunar landing as well as operation sequences in the development of Korean lunar exploration is scheduled. Therefore, the configuration and analysis of overall mission of Chang'e-3 is performed based on the public information from the press and website. As a result, overall mission trajectory is reconstructed by solving boundary condition and then estimating control variable. Visibility status and eclipse status also analyzes so communication and power charge condition is as good as to operate lunar lander. Mass budget of the lander is derived using ${\Delta}V$ according to specific impulse.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.2
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• pp.138-149
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• 2003

Korean regional network of tower flux sites, KoFlux, has been initiated to better understand $CO_2$, water and energy exchange between ecosystems and the atmosphere, and to contribute to regional, continental, and global observation networks such as FLUXNET and CEOP. Due to heterogeneous surface characteristics, most of KoFlux towers are located in non-ideal sites. In order to quantify carbon and energy exchange and to scale them up from plot scales to a region scale, applications of various methods combining measurement and modeling are needed. In an attempt to infer regional-scale flux, four methods (i.e., tower flux, convective boundary layer (CBL) budget method, MM5 mesoscale model, and NCAR/NCEP reanalysis data) were employed to estimate sensible heat flux representing different surface areas. Our preliminary results showed that (1) sensible heat flux from the tower in Haenam farmland revealed heterogeneous surface characteristics of the site; (2) sensible heat flux from CBL method was sensitive to the estimation of advection; and (3) MM5 mesoscale model produced regional fluxes that were comparable to tower fluxes. In view of the spatial heterogeneity of the site and inherent differences in spatial scale between the methods, however, the spatial representativeness of tower flux need to be quantified based on footprint climatology, geographic information system, and the patch scale analysis of satellite images of the study site.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.152-158
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• 2004

A low phase noise frequency synthesizer at X-Band which employs the subharmonic injection locking was designed and tested. The designed frequency synthesizer consists of a 1.75 GHz master oscillator - which also operates as a harmonic generator - and a 10.5 GHz slave oscillator. A 1.75 GHz master oscillator based on PLL technique used two transistors - one constitutes the active part of VCO and the other operates as a buffer amplifier as well as harmonic generator. The first stage operates a fixed locked oscillator and using the BJT transistor whose cutoff frequency is 45 GHz, the second stage is designed, operating as a harmonic generator. The 6th harmonic which is produced from the harmonic generator is injected into the following slave oscillator which also behaves as an amplifier having about 45 dB gain. The realized frequency synthesizer has a 7.4 V/49 mA, -0.5 V/4 mA of the low DC power consumption, 4.53 dBm of output power, and a phase noise of -95.09 dBc/Hz and -108.90 dBc/Hz at the 10 kHz and 100 kHz offset frequency, respectively.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1155-1161
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• 2001

Yittrium Iron Garnet(YIG) has been used as an important material in the circulator/isolator which is used in RF communication system, mobile phone, adn satellite broadcasting, etc. In this study, we investigated the microstructural and magnetic properties of YIG ferrites with the sintering temperature and additives. We fabricated the YIG ferrites substituted with Ca, In, V by the traditional ceramic sintering method at 1250$\^{C}$, 1275$\^{C}$, 1300$\^{C}$ and 1325$\^{C}$. Powders were granulated by using a spray dryer. Crystallographic and microstructural properties were measured by using XRD and SEM. Magnetic properties were measured by using a VSM for saturation magnetization (4$\pi$M$\_$s/) and FMR (Ferromagnetic Resonance) experiment for ferromagnetic resonance line width (△H). The YIG ferrite, Y$\_$1.6/Ca$\_$1.4/Fe$_4$V$\_$0.7/In$\_$0.3/O$\_$12/, sintered at 1300$\^{C}$, showed higher saturation magnetization and lower ferromagnetic resonance line width than any other sintering temperatures.