• Communications for Statistical Applications and Methods
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• 제26권2호
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• pp.205-216
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• 2019

Diagnostic tests in medical fields detect or diagnose a disease with results measured by continuous or discrete ordinal data. The performance of a diagnostic test is summarized using the receiver operating characteristic (ROC) curve and the area under the curve (AUC). The diagnostic test is considered clinically useful if the outcomes in actually-positive cases are higher than actually-negative cases and the ROC curve is concave. In this study, we apply the stochastic ordering method in a Bayesian hierarchical model to estimate the proper ROC curve and AUC when the diagnostic test results are measured in discrete ordinal data. We compare the conventional binormal model and binormal model under stochastic ordering. The simulation results and real data analysis for breast cancer indicate that the binormal model under stochastic ordering can be used to estimate the proper ROC curve with a small bias even though the sample sizes were small or the sample size of actually-negative cases varied from actually-positive cases. Therefore, it is appropriate to consider the binormal model under stochastic ordering in the presence of large differences for a sample size between actually-negative and actually-positive groups.

• 한국습지학회지
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• 제19권3호
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• pp.335-344
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• 2017

본 연구에서는 미계측유역의 설계홍수량을 산정하는 방안으로 유역의 면적비를 적용하는 방안을 제안하였다. 이를 위해 유역출구에서의 실측자료를 활용하여 유출매개변수를 결정하고 면적비를 적용하여 첨두홍수량을 산정하였다. 위 방법론을 검증하기 위해 소하천 유역의 관측유량 및 하천정비종합계획의 설계홍수량과의 비교를 통해 면적비 전이 방법론의 타당성을 검토하였다. 그 결과를 정리하면 다음과 같다. 면적비를 적용한 유출량과 관측유량자료를 비교한 결과 14~25% 정도의 차이를 보였다. 제안된 방법론의 타당성을 재확인하기 위해 하천정비종합계획에서 산정된 첨두유량과 소유역과의 면적비로 계산한 첨두유량을 비교하였다. 이를 위해 31개소의 소하천을 대상으로 설계홍수량을 비교한 결과, 20% 정도의 홍수량의 차이가 발생하였다. 따라서 면적비를 적용한 미계측지역에서의 첨두유량 산정방법론이 타당하다고 판단된다.

• 한국측량학회지
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• 제33권6호
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• pp.497-506
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• 2015

Gravity variations due to the 2011 Tohoku (M9.0) earthquake, which occurred at the plate boundaries near the northeastern coast of Japan, were estimated through the GRACE spherical harmonic (Stokes) coefficients derived from the CSR. About -5 μGal gravity variation by the GRACE data was found in the back-arc basin area with respect to a reference gravity model. The mean gravity variations in the back-arc basin area and the Japan Trench area were -4.4 and -3.2 μGal in order. The small negative gravity variations around the Japan Trench area can be interpreted by both crustal dilatation and the seafloor topography change in comparison with the large negative gravity variations in the back-arc basin area by co-seismic crustal dilatation of the landward plate. From the results of the gravity variations, vertical displacements generated from relatively short wavelength caused by the earthquake were estimated by use of multi-beam bathymetric measurements obtained from JAMSTEC. The maximum seafloor topography changes of about ±50 m were found at west side of the Japan Trench axis by the earthquake. The seafloor topography change by the megathrust earthquake can be considered as the results of the landslide of the seafloor throughout the landward side.

• 한국농공학회논문집
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• 제52권6호
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• pp.1-7
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• 2010

This study was carried out to investigate the effect of hydro power factors (e.g., irrigation area, watershed area, active storage, gross head) on annual generation capacity and operation ratio for agricultural reservoirs in Chungbuk Province with active storage of over 1 million $m^3$. The annual generation capacity and operation ratio were estimated using HOMWRS (Hydrological Operation Model for Water Resources System) from last 10-year daily hydrological data. The correlation coefficients between annual generation capacity and the hydro power factors except gross head were high (over 0.87), but the correlation coefficients between operational rate and the factors were low (below 0.28). The optimum multiple regression equations of the annual generation capacity were expressed as the functions of watershed area, active storage, and gross head. Also, the simple regression equation of annual generation capacity was expressed as a function of watershed area. The average relative root-mean-square-error (RRMSE) between observed and estimated values by the optimum multiple regression equations was smaller than that by the simple regression equation, suggesting that the former has more accuracy than the latter.

• 한국습지학회지
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• 제8권4호
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• pp.33-40
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• 2006

The water of rivers and lakes in Korea is the main sources for drinking, industrial and agricultural purposes. However, various pollutants washed-off from watershed area make worse and worse the water quality. Particularly, the changes of land uses in watershed area is the main pollutant sources in many cases in Korea, it is usually called to nonpoint pollution sources. In this reason, the Ministry of Environment are programing the total maximum daily load for four major large rivers in order to improve the water quality by controlling the watershed area. Therefore, this research was performed to estimate the total pollutant input from watershed areas to lakes of Ganwol and Boonam located in Chungnamdo. The AGNPS water quality model and monitoring were used to estimate the pollutant loading rates with unit pollutant concentration of each land use. The main landuse of the research area are forest, wet and dry paddy field and small urban area. The research shows that the pollutant sources in Ganwol and Boonam lakes are from the various landuses. In this manuscripts, the results will provide important informations for mitigating the pollutants to the lakes.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.4-4
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• 2020

Three wildfires severely damaged local towns and forests in Gangwon-do, South Korea in 2019 April 4-5. Local hydrological regime could be greatly altered by the wildfires, therefore it is important to assess its damage (e.g. area and severity) and also resultant changes in hydrological fluxes. We retrieved the Normalized-Burned Ratio (NBR) index using remote-sensing data (Moderate Resolution Imaging Spectroradiometer (MODIS) 500-m 8-day surface reflectance data), and delineated the damaged-area based on the difference in the NBR (dNBR) before and after the wildfires. We then estimated changes in the annual evapotranspiration (AET) in 2019 using the MODIS evapotranspiration data (500-m 8-day). It was found that the damaged-area of the three wildfires was 29.50 km^2 in total, which take up 1.00-6.19% area of five catchments. It was estimated that the AET would be decreased as 0.05-1.56% over those five catchments, as compared to the pre-fire AET (2004-2018). The impact of the wildfires on the catchment AET was less severe than expected (i.e. up to 1.56%) mostly because two big wildfires were distributed across two catchments respectively (i.e. four catchments for the two wildfires) and the other wildfire was small and not severe. This study highlights the importance of assessing the area and severity of a wildfire when estimating its impact on the local hydrological cycle.

• 한국방재학회 논문집
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• 제1권1호
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• pp.103-115
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• 2001

현재 소규모 유역에서의 수공구조물의 설계시 확률강우강도식을 사용하여 강우량을 산정하는 것이 일반적인 적용방법으로 이용되어지고있다. 확률강우의 산정은 그 자체로서 불확실성을 많이 내포하고 있으나 현실적으로 강우의 비선형성을 해석함에 있어 단순화는 배제 할 수 없는 필요사항이다. 따라서 본 연구에서는 확률강우량 산정을 위한 강우강도식의 산정에 있어서 그 비선형성을 잘 모의할 수 있는 방법에 관하여 연구하여 보았다. 연구결과에 의하면 유전자 알고리즘이 시산법이나 비선형계획법의 일종인 Powell 기법에 비하여 더 신뢰성 높은 방법임을 알 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권12호
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• pp.5978-5999
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• 2018

Pedestrian detection is a challenging area in the intelligent vehicles domain. During the last years, many works have been proposed to efficiently detect motion in images. However, the problem becomes more complex when it comes to detecting moving areas while the vehicle is also moving. This paper presents a variational optical flow-based method for motion estimation in vehicular traffic scenarios. We introduce a framework for detecting motion areas with small and large displacements by computing optical flow using a multilevel architecture. The flow field is estimated at the shortest level and then successively computed until the largest level. We include a filtering parameter and a warping process using bicubic interpolation to combine the intermediate flow fields computed at each level during optimization to gain better performance. Furthermore, we find that by including a penalization function, our system is able to effectively reduce the presence of outliers and deal with all expected circumstances in real scenes. Experimental results are performed on various image sequences from Daimler Pedestrian Dataset that includes urban traffic scenarios. Our evaluation demonstrates that despite the complexity of the evaluated scenes, the motion areas with both moving and static camera can be effectively identified.

• 한국도서관정보학회지
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• 제42권4호
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• pp.375-393
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• 2011

작은도서관이 공공도서관의 영역에 포함되면서 작은도서관의 제도적 보완, 지원 정책틀 마련, 운영활성화를 위한 정책적 결정을 하여야 하는 시기에 이르렀다. 이러한 정책결정 도구로서 도서관통계가 충실하게 이루어지도록 작은도서관 통계지표를 개선할 필요가 있다. 현재의 작은도서관통계(문고)는 2008년 마련된 공공도서관 통계의 틀에 일부항목을 수정하여 국가도서관통계에서 활용하고 있다. 하지만 항목의 불합리성으로 91.3%의 무응답율과 수집된 데이터의 오류가 상당히 많다. 본 연구에서 개선을 위하여 작은도서관 현황조사 4종, 평가기준 7종을 분석하고, 이를 기초로 하여 2차에 걸친 자문회의, 경기도 지역의 3개 지자체 작은도서관 108개관의 현장조사 결과를 반영하여 개선된 통계지표를 제시하였다. 제시된 통계는 7개 영역 37개 항목이다.

• 한국수자원학회논문집
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• 제37권5호
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• pp.397-406
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• 2004

어떤 특정 지역의 지하수 개발량을 적적히 파악하기 위해서는 지하수함양량의 산정이 필요하다. 경상북도에 위치한 위천 유역내의 소유역에 대하여 지하수 함양량을 산정하였다. 기저유출분리법과 SCS-CN방법을 이용하여 갈수년과 풍수년이 존재하는 1992년∼1997년간의 년 평균 지하수 함양량을 추정하였다. 기저유출분리법을 이용하여 추정한 결과, 연평균 지하수 함양률이 11.9%∼18.7%로 변화하였으며 계산기간 중의 년 평균 강수에 의한 지하수 함양량은 141.6mm로 지하수함양률은 14.5%이었다. SCS-CN방법을 이용하여 추정한 결과, 연평균 지하수 함양균이 7.9%∼20.9%로 변화하였으며 계산기간 중의 년 평균 강수에 의한 피하수 함양량은 147.4mm 로 지하수 함양률은 15.1%이었다. 두 방법으로 산정한 갈수년과 풍수년이 존재하는 장기간 동안의 년 평균 강수에 의한 지하수 함양량은 지하수 개발에 유용하게 사용할 수 있음을 나타낸다.