• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권2호
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• pp.68-73
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• 2002

In compared with air insulated switchgear, GIS has a high efficiency and confidence. Insulation method using $SF_6$ gas has a very excellent insulation characteristic for high voltage equipment but has a characteristic that insulation heredity is changed for internal unequal electric field. So analysis of time varying electromagnetic field in GIS is very important for structure design and trouble diagnosis process. In compared with established method, the SNM(Spatial Network Method) in this Paper can observe variation of electromagnetic field with real time and get result very similar to measurement. In order to Know variation of electromagnetic field distribution in fast moving particle, we make used of SNM.

• 한국농림기상학회지
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• 제4권3호
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• pp.175-196
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• 2002

The increase of meteorological uncertainty and unstable fluctuation of its behavior due to the global warming affect the temporal variation and spatial distribution of water resources and water use patterns in agriculture. There have been steady efforts to understand hydrological components and deal with such water related problems. This paper reviews firstly, the future effect of water resources due to climate changes, secondly, recent progress for precipitation, evapotranspiration, soil moisture, and thirdly, GIS/RS based integrated information systems conducted by both researchers and government ministries. There should be continuous studies and investments to cope with climate changes, and to accomplish sustainable development with the help of agricultural water resources. Some research topics were suggested to attempt with substantial contents considering our present capability and situation.

• 생명과학회지
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• 제20권9호
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• pp.1287-1293
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• 2010

RAPD에 의한 지리산 내 산거울 집단의 유전자 빈도와 지리적 거리에 따른 공간적 상관관계를 분석하였다. 전체 102 DNA 분절(밴드)이 107 개체에서 탐지되었다. 102 밴드 중 48(47.1%)개 밴드는 다형성을 나타내었다. 분집단간 다형성의 비교에서 거리 구간 I와 V가 가장 낮은 변이(16.7%)를 나타내었고, 거리 구간 VIII이 가장 높은 변이를 나타내었다(22.6%). 전체 다양도는 0.076이었다. 구간 VIII이 가장 높은 다양도(0.093)를 나타내었고, 구간 I가 가장 낮았다(0.063). 구간 사이의 유전적 유사도는 60 m 거리까지는 유사하였다. 지리산 집단에서 산거울은 강한 공간구조를 나타내고 있음이 RAPD 마커로 알 수 있었다. 이는 지리산 집단에서 낮은 이주자수와 개체들이 덩어리 모양의 분포를 나타내기 때문으로 판단된다. 본 연구에서 RAPD 마커로 산거울의 공간구조와 유전적 구조를 파악하는데 유용하게 이용될 수 있음을 입증하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.82-84
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• 2003

Watershed boundaries and flow paths within the watershed are the most important factors required in watershed analysis. Most often the derivation of watershed boundaries and stream network and flow paths is based on topographical maps but spatial variation of flow direction is not clearly understandable using this method. Water resources projects currently use 1: 50, 000-scale ground survey or aerial photography-based topographical maps to derive watershed boundary and stream network. In basins, where these maps are not available or not accessible it creates a real barrier to watershed geo-spatial analysis. Such situations require the use of global datasets, like GTOPO30. Global data sets like ETOPO5, GTOPO30 are the only data sets, which can be used to derive basin boundaries and stream network and other terrain variations like slope aspects and flow direction and flow accumulation of the watershed in the absence of topographic maps. Approximately 1-km grid-based GTOPO 30 data sets can derive better outputs for larger basins, but they fail in flat areas like the Karkheh basin in Iran and the Amudarya in Uzbekistan. A new window in geo-spatial hydrology has opened after the launching of the space-borne satellite stereo pair of the Terra ASTER sensor. ASTER data sets are available at very low cost for most areas of the world and global coverage is expected within the next four years. The DEM generated from ASTER data has a reasonably good accuracy, which can be used effectively for hydrology application, even in small basins. This paper demonstrates the use of stereo pairs in the generation of ASTER DEMs, the application of ASTER DEM for watershed boundary delineation, sub-watershed delineation and explores the possibility of understanding the drainage flow paths in irrigation command areas. All the ASTER derived products were compared with GTOPO and 1:50,000-based topographic map products and this comparison showed that ASTER stereo pairs can derive very good data sets for all the basins with good spatial variation, which are equal in quality to 1:50,000 scale maps-based products.

• Journal of Electrochemical Science and Technology
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• 제8권4호
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• pp.331-337
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• 2017

A simple strategy is proposed herein for attaining uniform current distribution in direct methanol fuel cells by varying the catalyst loading over the electrode. In order to use the same total catalyst amount for a serpentine flow field, three spatial variation types of catalyst loading were selected: enhancing the cathode catalyst loading (i) near the cathode outlet, (ii) near the cathode inlet, and (iii) near the lateral areas. These variations in catalyst loading are shown to improve the homogeneity of the current distribution, particularly at lower currents and lower air-flow rates. Among these three variations, increased loading near the lateral areas was shown to contribute most to achieving a homogenous current distribution. The mechanism underlying each catalyst loading variation method is different; very high catalyst-loading is shown to decrease the homogeneity of the distribution, which may be caused by water management in the thick catalyst layer thereof.

• 한국수산과학회지
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• 제46권1호
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• pp.59-69
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• 2013

Temporal and spatial variation in the freshwater region, created by river runoff, of a small bay, caused by the passage of typhoons was examined using a three-dimensional primitive equation model (the Princeton Ocean Model, POM). Numerical experiments were implemented focusing on temporal evolution in the freshwater region in association with typhoon tracks. The model domain covered most of the estuary around the Nakdong River, including Noksan Bay, where river water is periodically released from upstream (Noksan dam). The model showed that the extension of the freshwater region outside of the bay depended strongly on the tracks of typhoons, specifically the associated wind directions and inner flow fields that are accompanied by new clockwise eddies. The model also showed that entrainment from typhoon passage frequently creates salt wedges in the estuary, indicating that organisms in the bay are biologically and chemically influenced with variation in the freshwater region.

• 한국공간구조학회논문집
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• 제18권3호
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• pp.67-74
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• 2018

Recently, measuring instruments for SHM of structures has been developed. In general, the wireless transmission of sensor signals, compared to its wired counterpart, is preferable due to the absence of triboelectric noise and elimination of the requirement of a cumbersome cable. However, in extreme environments, the sensor may be less sensitive to temperature changes and to the distance between the sensor and data logger. This may compromise on the performance of the sensor and instrumentation. Therefore, in this paper, free vibration experiments were conducted using wireless MEMS sensors at an actual site. Measurement was assessed in time and frequency domain by changing the temperature variation at($-8^{\circ}C$, $-12^{\circ}C$ and $-16^{\circ}C$) and the communication distance (20m, 40m, 60m, 80m).

• Journal of the Optical Society of Korea
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• 제20권6호
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• pp.752-761
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• 2016

Hyperspectral images are often contaminated with stripe noise, which severely degrades the imaging quality and the precision of the subsequent processing. In this paper, a variational model is proposed by employing spectral-spatial adaptive unidirectional variation and a sparse representation. Unlike traditional methods, we exploit the spectral correction and remove stripes in different bands and different regions adaptively, instead of selecting parameters band by band. The regularization strength adapts to the spectrally varying stripe intensities and the spatially varying texture information. Spectral correlation is exploited via dictionary learning in the sparse representation framework to prevent spectral distortion. Moreover, the minimization problem, which contains two unsmooth and inseparable $l_1$-norm terms, is optimized by the split Bregman approach. Experimental results, on datasets from several imaging systems, demonstrate that the proposed method can remove stripe noise effectively and adaptively, as well as preserve original detail information.

• Geomechanics and Engineering
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• 제38권1호
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• pp.93-106
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• 2024

The present paper investigates the spatial variability effect of soil property on the three-dimensional probabilistic characteristics of the bearing capacity factor (i.e., mean and coefficient of variation) of a circular footing resting on clayey soil where both mean and standard deviation of undrained shear strength increases with depth, keeping the coefficient of variation constant. The mean trend of undrained shear strength is defined by introducing the dimensionless strength gradient parameter. The finite difference method along with the random field and Monte Carlo simulation technique, is used to execute the numerical analyses. The lognormal distribution is chosen to generate random fields of the undrained shear strength. In the study, the potential failure of the structure is represented through the failure probability. The influences of different vertical scales of fluctuation, dimensionless strength gradient parameters, and coefficient of variation of undrained shear strength on the probabilistic characteristics of the bearing capacity factor and failure probability of the footing, along with the probability and cumulative density functions, are explored in this study. The variations of failure probability for different factors of safety corresponding to different parameters are also illustrated. The results are presented in non-dimensional form as they might be helpful to the practicing engineers dealing with this type of problem.

• 한국지리정보학회지
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• 제17권3호
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• pp.147-159
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• 2014

높은 수준의 TOD(대중교통 지향형 도시개발 : Transit Oriented Development)계획요소는 도시민의 대중교통 이용수요를 상승시키고 이는 지역의 보행환경을 개선하는 결과를 가져올 수 있다. 일반적으로 TOD 계획요소는 역세권 주변의 토지이용에 대한 다양성과 대중교통의 접근성, 그외 도시디자인 측면에서 평가되어 왔다. 특히 지하철역을 중심으로 하는 역세권 개발의 특성상 TOD 계획요소의 공간특성은 주변지역의 범위설정에 의존적일 가능성이 존재한다. 또한 물리적 TOD계획요소 이외에 지역의 사회경제적 특성 또한 대중교통의 수요에 큰 영향을 미칠 수 있다. 따라서 TOD에 관한 연구 시 권역설정에 따른 계획요소의 공간특성 변화와 해당지역의 사회경제적 특성을 주목할 필요가 있다. 본 연구에서는 부산시 지하철 역 주변을 대상으로 상이한 공간단위별로 도출된 TOD 계획 수준의 변화를 분석하였다. 또한 지하철 이용객 수와의 다중회귀분석을 통해 효과적인 TOD계획요소의 분석 공간단위를 탐색하였다. 이와 병행하여 사회경제적 요소를 추가적으로 적용한 다중 회귀모형과의 비교분석을 수행하여 TOD계획지표 이외에 사회경제적 변수의 적용 가능성을 검토하였다. 분석결과 공간단위의 설정에 따라 TOD계획지표의 공간분포에 변동성을 발견하였고 연구지역에서 효과적으로 적용 가능한 특정 공간단위를 도출하였다. 또한 물리적 TOD계획요소 이외에 추가적으로 사회경제적 변수를 적용한 다중 회귀모형이 보다 개선된 추론결과를 도출하였다.