• 대한수학회보
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• 제44권3호
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• pp.547-567
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• 2007

We obtain spatial-temporal decay rates of weak solutions of incompressible flows in exterior domains. When a domain has a boundary, the pressure term yields difficulties since we do not have enough information on the pressure term near the boundary. For our calculations we provide an idea which does not require any pressure information. We also estimated the spatial and temporal asymptotic behavior for strong solutions.

• 대한수학회지
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• 제49권6호
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• pp.1163-1174
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• 2012

This paper examines a temperature dependent Stokes flow in a semi-infinite cylinder. Under appropriate initial and boundary conditions the author establishes exponential decay of solutions in energy norm with distance from the finite end of the cylinder.

• 조명전기설비학회논문지
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• 제29권7호
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• pp.80-86
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• 2015

As wind farm outputs depend on natural wind resources that vary over space and time, spatial correlation analysis is needed to estimate power outputs of wind generation resources. As a result, geographic information such as latitude and longitude plays a key role to estimate power outputs of spatially distributed wind farms. In this paper, we introduce spatial correlation analysis to estimate the power outputs produced by wind farms that are geographically distributed. We present spatial correlation analysis of empirical power output data for the JEJU Island and ERCOT ISO (Texas) wind farms and propose the Correlation Decay Distance (CoDecDist) model based on geographic correlation analysis to enhance the estimation of wind power outputs.

• 한국환경과학회지
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• 제27권7호
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• pp.499-507
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• 2018

Agricultural meteorological information is an important resource that affects farmers' income, food security, and agricultural conditions. Thus, such data are used in various fields that are responsible for planning, enforcing, and evaluating agricultural policies. The meteorological information obtained from automatic weather observation systems operated by rural development agencies contains missing values owing to temporary mechanical or communication deficiencies. It is known that missing values lead to reduction in the reliability and validity of the model. In this study, the hierarchical Bayesian spatio-temporal model suggests replacements for missing values because the meteorological information includes spatio-temporal correlation. The prior distribution is very important in the Bayesian approach. However, we found a problem where the spatial decay parameter was not converged through the trace plot. A suitable spatial decay parameter, estimated on the bias of root-mean-square error (RMSE), which was determined to be the difference between the predicted and observed values. The latitude, longitude, and altitude were considered as covariates. The estimated spatial decay parameters were 0.041 and 0.039, for the spatio-temporal model with latitude and longitude and for latitude, longitude, and altitude, respectively. The posterior distributions were stable after the spatial decay parameter was fixed. root mean square error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE), and bias were calculated for model validation. Finally, the missing values were generated using the independent Gaussian process model.

• 대한수학회지
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• 제48권6호
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• pp.1153-1170
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• 2011

In this paper, spatial decay estimates for the time dependent compressible viscous isentropic flow in a semi-infinite three dimensional pipe are derived. An upper bound for the total energy in terms of the initial boundary data is obtained as well. The results established in this paper may be viewed as a version of Saint-Venant's principle in transient compressible Navier-Stokes flow.

• 지역연구
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• 제31권2호
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• pp.47-61
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• 2015

이 연구의 목적은 수도권을 대상으로 입지를 변경한 기업들의 거리감쇄효과를 실증분석하는 것이다. 기업은 이전할 때 이전비용부담과 해당지역의 고객확보, 관련업체와의 협력 등으로 해당지역과 근접한 지역으로 재입지 하려는 경향을 나타낸다. 따라서 기업의 입지변경 시 이동거리는 기존 입지지역과 최대한 가까운 지역에 재입지하려는 거리감쇄효과가 발생한다. 본 연구는 수도권 소재의 서비스업과 제조업, 건설업 기업들의 기업이동 거리감쇄함수를 구축하고 그 효과를 실증분석하였다. 실증분석결과 서비스업과 제조업, 건설업 모든 기업의 거리감쇄효과가 있음을 확인하였으며, 구축한 거리감쇄함수의 설명력($R^2$)은 제조업은 .802, 서비스업은 .812, 건설업은 .728로 높은 설명력을 나타냈다. 이는 기업이동에 대한 거리감쇄효과가 있음을 실증한 것이며, 또한 건설업과 서비스업, 제조업 순서로 거리감쇄효과가 큼을 도출하였다.

• 대한원격탐사학회지
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• 제36권3호
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• pp.401-410
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• 2020

최근 지구 온난화의 영향으로 변화하는 한반도 식물계절에 대한 연구가 많이 이루어지고 있다. 그러나 지리적인 특성상 봄철 식물계절에 비해 실측이 어려운 가을철 식물계절의 연구는 미비한 실정이다. 이에 본 연구에서는 대표적인 가을철 식물계절인 단풍과 낙엽 등을 '마른 잎'으로 정의하고 Landsat-8 위성영상을 기반으로 마른 잎 탐지를 수행하였다. NDVI를 이용하여 마른 잎의 1차 경계 값을 산출하고, 건강한 잎과의 분광특성 차이 및 NDWI를 이용하여 마른 잎의 2차 경계 값을 산출하였다. 본 연구의 마른 잎 탐지 알고리즘의 정확도 검증을 위해 POD, FAR 값을 이용하였으며, 검증 결과 POD는 98.619, FAR은 1.203으로 높은 정확성을 보였다.

• 한국수학사학회지
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• 제13권2호
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• pp.87-94
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• 2000

This paper investigates history and modern developments concerning spatial decay estimates for solutions in a semi-infinite cylinder or strip, in which model equations are defined with appropriate homogeneous lateral boundary conditions and initial conditions but left end boundary data are assumed. Our aim is to show this Saint-Venant type decay rate dependent critically on the Poincare constant resulting from characterizing variational principles.

• 한국주거학회논문집
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• 제20권2호
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• pp.109-118
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• 2009

In general, the decay of the residential district has been considered a phenomenon of old towns. But now it has become a problem of new development areas too, which have been a cause of the decay of old town. This study aims to investigate the decay of the residential district in the new development area. The survey site was Dunsan, a town-intown of Daejeon metropolitan city. The findings were as follows (:) 1) even in the new development area, a high level of vacancy ratio was evident. ; 2) among the buildings above ground, 1st floor showed the highest vacancy ratio, which means the 1st floor was allotted to too many commercial facilities relative to the buying power size in this district. ; 3) there were many conversions in response to the decay of the district, from residential to commercial, and commercial to residential. ; and 4) the allocation of each type of conversion showed a spatial pattern.

• 대한수학회보
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• 제48권2호
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• pp.397-412
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• 2011

In this paper, the equation of the transient Stokes flow of an incompressible viscous fluid is studied. Growth and decay estimates are established associating some appropriate cross sectional line and area integral measures. The method of the proof is based on a first-order differential inequality leading to an alternative of Phragm$\'{e}$n-Lindell$\"{o} $f type in terms of an area measure of the amplitude in question. In the case of decay, we also indicate how to bound the total energy.