• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2007년도 학술발표회 논문집
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• pp.253-257
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• 2007

Channel-aquifer interaction is one of the key hydrological processes that determine water flows in the stream/river channel. Field measurements of channel-aquifer interaction, however, is very difficult and costly, particularly when one intends to understand its variations across a catchment for a long period. Hydrological simulations using a catchment model are a relatively easier and cheaper alternative provided the model structure is appropriate for describing channel-aquifer interaction. In this study, a catchment model called CAMEL (Chemicals from Agricultural Management and Erosion Losses) is used for estimating channel-aquifer interaction over time and space. CAMEL is a distributed catchment model to simulate transformation and transport processes of sediment and pollutants as well as water flows at the catchment scale. In the model, a catchment is represented using a network of square columns each of which is comprised of various storages of water. CAMEL explicitly simulates both surface and subsurface processes including channel-aquifer interaction. This paper presents an application study results of CAMEL for the Tarland Burn Catchment, a small (catchment area $52\;km^2$) rural catchment in Scotland, UK, demonstrating some of the channel-aquifer interaction dynamics across the catchment during a 2-year period.

• 한국공간정보시스템학회:학술대회논문집
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• 한국공간정보시스템학회 2004년도 국내 LBS 기술개발 및 표준화 동향세미나
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• pp.147-152
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• 2004

OGC에서는 다양한 분야의 지리공간 정보를 손쉽게 상호 운용하기 위해 이질적인 환경의 지리공간 정보를 XML로 인코딩하는 GML 명세를 제시하였다. 그러나 GML 문서는 텍스트 구조로 되어있어 데이타 용량이 커지며 전송 시 속도가 현저히 저하되고, 문서 스캔 비용이 많이 든다는 문제가 있다. 그러므로, 대용량의 GML 문서를 정보 손실 없이 변환하여 전송 속도와 문서 스캔 속도를 향상시키기 위한 방법이 필요하다. 이에 OGC에서는 최근 바이너리 XML 형식인 BXML을 제안하였다. 본 논문에서는 BXML 형식을 사용하여 GML 문서를 토큰화하고, 토큰을 정의된 바이트 코드로 변환하여 문서의 크기를 줄이고 전송 속도와 문서 스캔 속도를 향상시키는 효율적인 GML 문서 변환 및 전송 시스템을 설계하고 구현하였다. GML 운서 변환 및 전송 시스템은 GML 문서와 BXML 문서를 상호 변환하는 기능과 BXML 문서에서 공간 데이타를 추출하여 디스플레이 하는 기능을 제공한다. 성능 평가 결과 GML 문서 변환 및 전송 시스템 사용시 GML 문서의 크기는 최대 80% 감소하였고 전송 속도는 최대 3.5배 향상되었다.

• 한국환경복원기술학회지
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• 제15권2호
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• pp.149-162
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• 2012

Habitat loss and fragmentation are ongoing major anthropogenic impacts on landscapes, which can strongly affect ecosystems, populations and species. The studies on forest fragmentation have been progressed, but the studies on definition of forest fragmentation and their synthetic trend in South Korea still leaves much to be desired. Therefore we set the definition of forest fragmentation and reviewed the related papers. We can give a definition that forest fragmentation is not only a process of spatial landscape transformation, but also a process of ecosystem change by it. The trend of studies on forest fragmentation divided into two fields, landscape and ecosystem changes. Forest fragmentation caused by land change altered the composition and configuration of forest patches. Most studies related on that analyzed the change using landscape index. The effects of forest fragmentation on ecosystem subdivided into three fields : biodiversity, edge effects, and invasive species, but the studies in South Korea is short. The study on relations between forest fragmentation and ecosystem change is necessary to face the Convention on Biological Diversity in South Korea. In addition, the fundamental studies on biodiversity is important to mitigate against forest fragmentation.

• 대한공간정보학회지
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• 제12권2호
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• pp.67-71
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• 2004

위성영상의 종류가 증가하고 취득이 용이해 짐에 따라 위성영상을 이용한 수치고도모형의 생성에 관한 연구가 활발히 진행되어 왔다. SPOT의 경우 $60km{\times}60km$에 해당하는 광범위한 지역에 대한 영상을 취득할 수 있어 넓은 지역에 대한 수치고도모형을 생성 할 수 있는 이점이 있다. 기존의 엄밀센서모형(Rigorous Sensor Model)의 경우 위성의 천문력자료(Ephemeris Data)와 지상기준점을 사용하여 복잡한 과정을 거쳐 DEM을 생성하였으나 본 연구에서는 직접선형변환(DLT)에 기반을 둔 대안적 모형화 기법을 이용하여 DEM을 생성해 보았다. 결과적으로 직접선형 변환의 경우 소수의 기준점을 통하여 양호한 품질의 DEM을 취득할 수 있음을 확인 할 수 있었다.

• 대한공간정보학회지
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• 제8권2호
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• pp.47-60
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• 2000

본 연구에서는 인공위성영상을 이용한 토지피복 분류방법 중 파라메트릭한 분류와 비-파라메트릭한 분류의 대표성을 띤 최대우도 분류법과 신경망을 이용한 분류방법을 사용하여 분류정확도를 비교하였다. 분류정확도의 평가에 있어서 일반적인 분석가들이 사용하는 훈련지역에 대한 분류 정확도의 분석뿐만 아니라, 시험지역에 대한 정확도분석을 하였다. 그 결과, 최대우도분류기에 비하여 신경망의 분류기가 일반적인 훈련데이터의 분류에 있어서 약 3% 우월하였으며, 지상검증데이터를 사용한 분류결과에서는 시험에 사용된 두 분류기 모두 빈약한 분류결과를 나타내었으나, 신경망에 의한 분류가 최대우도에 비하여 약 10%정도 보다 신뢰할 수 있는 결과를 얻을 수 있었다.

• 소음진동
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• 제5권2호
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• pp.169-181
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• 1995

A theoretical model has been studied to describe the sound radiation analysis for structural vibration noise control of tire under the action of random moving line forces. When a tire is analyzed, it has been modeled as a curved beam with distributed springs and dash-pots which represent the radial, tangential stiffness and damping of tire, respectively. The reaction due to fluid loading on the vibratory response of the curved beam is taken into account. The curved beam is assumed to occupy the plane y = 0 and to be axially infinite. The material of curved beam and elastic foundation are assumed to be lossless, and governed by the law of Bernoulli-Euler beam theory. The expression for sound power is integrated numerically and its results examined as a function of Mach number(M), wavenumber ratio(.gamma.) and stiffness factor(.PSI.). The experimental investigation for structural vibration noise of tire under the action of random moving line forces has been made. Based on the STSF(Spatial Transformation of Sound Field) techniques, the sound power and sound radiation are measured. The experimental results show that operating condition, material properties and design factors of the tire have a great effect on the sound power and sound radiation characteristics.

• 대한전자공학회논문지SD
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• 제37권9호
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• pp.38-46
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• 2000

본 논문에서는 신뢰성이 높고, 효율적으로 최적해에 도달하는 GA 학습기법을 광 연결에 응용하기 위한 소자 설계에 적용하였다. 실시간에 가까운 광 신호 처리를 위해 프로그래머블 SLM에 CGH 공간 필터를 입력하여 복합 광 신호 처리 시스템을 구성하여 실험하였다. 광학 실험에 의해 실제로 CCD 배열 검출기에서 얻어진 스폿 빔을 정략적인 데이터로 측정하기 위해 기하학적인 변형을 수행한 결과, $3{\times}3$ 스폿 빔에 대하여 그레이 레벨로서 스폿 빔들의 평균이 202, 최대값이 225, 최소값이 186으로 얻어졌고, 균일도가 $1.93{\times}10^{-1}$ 로서 시뮬레이션 결과와 유사하게 안정된 분포로 출력되었다.

• 한국실내디자인학회논문집
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• 제23권4호
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• pp.63-71
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• 2014

Anamorphosis is highly favored in modern days as the atmosphere of pursuing unusual manners is growing while transformation and distortion of images are freely available. This research is to understand the affect of these distorted images on space designs and the close connection between anamorphosis and visual perceptions, and to identify the new perceptual phenomenon created through it, and the methods of expressing those. Four expressional methods were defined through the process of studying Anamorphosis based on its definition by Niceron, examining artworks such as paintings and photographs, and case-studying example spaces of visual perception experiments. Expressing anamorphosis through visual perceptions are broadly categorized to directional, dimensional, flatness, and optical. The analysis of 10 case projects suggests that the experimental spaces offer joys of finding and interpreting metaphorical forms and meanings caused by the four characteristic categories above. Also, they artificially show the boundaries between reality and virtual spaces in 2-dimensional or 3-dimensional spaces, and form hyper-boundaries, new experience, and an internal mechanism that is vague and chaotic. Therefore, this research concludes that anamorphosis which is a distorted perspective, is not only a simple measure to overcome perspectival errors, but is an existence suitable to the current era, that will extend its potential and value in spatial design.

• 해양환경안전학회지
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• 제3권2호
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• pp.23-31
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• 1997

The results of high speed photography, acoustic emission detection and plasma UV radiation intensity measurement during CO2 laser welding of stainless steel 304 are presented. Video images with high spatial and temporal resolution allowed to observe the melt dynamics and keyhole evolution. The existence of a high speed melt flow which originated from the part of weld pool and flowed along the sides wall of keyhole was confirmed by the slag motion on the weld pool. the characteristic frequencies of flow instability and keyhole fluctuations at different welding speed were measured and compared with the results of Fourier analyses of temporal acoustic emission (AE) and light emission (LE) spectra. The experimental results were compared with the newly developed numerical model of keyhole dynamics. (The model is based on the assumption that the propagation of front part of keyhole into material is due to the melt ejection driven by laser induced surface evaporation.) The calculations predict that a high speed melt flow is induced at the front part of keyhole when the sample travel speed exceeds several 10mm/s. The numerical analysis also shows the hump formation on the front keyhole wall surface. Experimentally observed melt behavior and transformation of the AE and LE spectra with variation of welding speed are qualitatively in good agreement with the model predictions.

• 전자공학회논문지A
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• 제30A권3호
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• pp.76-87
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• 1993

We present a self-consistent, 2-dimensional solution of the Poisson and Sch rodinger equation based on the finite difference method with a nonuniform mesh size for a AlGaAs/GaInAs/GaAs HEMT devide. During the interative self-consistent calculation, however, we calculate Schrodinger equation only a some region of device, not a fully region in order to save the moemory and the speed-up of computation, and then use the approximated data for the other region using by a interpolation method with a given values. Also we adopt the proper matrix transformation method that allows preservation of the symmetric, form of the discretized Schrodinger equation, even with the use of a nonumiform mesh size, therefor, can reduce the computation time. We calculate the wavefunction, eigenstates and the electron concentration uat channel layer nder the thermal equilibrium and the biased conditions, respectively. Also,these parameters are used to solve 2-dimensional tdistribution of potential in he entire region of device. It is proved that the method is very efficient in finding eigenstages extending over relatively large spatial area without loss of accuracy. So, it can be used rather easily in any sarbitrary modulation doped utucture.