• 한국수자원학회논문집
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• 제43권12호
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• pp.1083-1091
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• 2010

분포형 수문 모형의 일강우 입력 자료는 불가피하게 불규칙하고 밀도가 낮은 관측망에서 기록된 값을 내삽해 사용하게 되나, 흔히 사용되는 대부분의 내삽법들은 실제 일강우의 다양한 공간적 분포를 잘 재현하지 못하는 문제가 있다. 본 연구에서는 널리 사용되는 다섯 가지의 강우 내삽 방법을 두개의 유역에 사용하여 비교하고 실제 공간적 분포를 보다 잘 나타낼 수 있는 2단계 내삽법을 제안하였다. 비교에 사용된 내삽법은 (1) 역가중치 방법(IDW), (2) 다중회귀분석 (MLR), (3) 월강우를 이용한 다중회귀분석법(CMLR), (4) 국지가중치 다중회귀분석(LWP) 등이다. 보다 향상된 내삽을 위한 2단계 내삽법은 먼저 로지스틱 회귀분석으로 강우-비강우 지역을 구분하고 강우 지역에서만 기존의 내삽법을 적용하여 강우량을 구하는 방법이다. 기존 방법과의 비교결과 공간적인 편차가 심한 일강우의 특성을 2단계 내삽법에서 잘 표현하고 있는 것으로 나타났다. 제안된 방법은 수문모형에의 적용뿐만 아니라 유출량의 예보 및 대기 순환 모형의 다운 스케일링에도 효과적으로 사용될 수 있을 것으로 기대된다.

• 한국산학기술학회논문지
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• 제21권5호
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• pp.466-475
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• 2020

콜센터 성과평가 및 인적자원 관리는 상담원의 개인적, 사회적 특성을 고려하지 않고 해결 콜 수에만 의존적으로 평가되고 있다. 그러나 콜센터는 대부분 업무가 고객과의 공동 문제해결에 기반하고 있어 상담원의 개인적 역량 및 사회적 역량이 업무성과에 직접적인 영향을 미친다. 따라서 본 연구는 콜센터 상담원을 대상으로 개인적 역량 및 조직 내 사회적 특성이 업무 성과에 미치는 영향을 분석함으로써 콜센터 성과평가 및 상담원의 채용관리에 도움을 주고자 한다. 이를 위해 본 연구는 RGT를 이용하여 개인적 특성을 도출하였고, 네트워크 분석을 통해 사회적 관계를 분석하였다. RGT와 네트워크 분석을 통해 도출된 변수를 바탕으로 회수실적과의 상관계수가 높은 항목을 선정한 후 회귀 분석을 실시하였다. 실험 결과, 회식망 내향 중앙성, 업무 적극성, 개방적 성향, 배우는 것을 즐기는 성향의 네 가지 특성이 회수실적에 유의미한 영향을 미치는 것으로 나타났다. 본 연구 결과는 콜센터 상담원 성과평가 뿐 아니라 상담원의 채용 및 관리에도 의미있는 정보를 제공할 수 있을 것으로 기대된다.

• 대한원격탐사학회지
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• 제20권2호
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• pp.65-76
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• 2004

본 연구는 위성으로부터 얻어진 지표온도와 Elevation Derivative Database(EDD)를 사용하여 일 최고기온을 산출하기 위해 수행되었다. 실험은 다중 회귀 분석을 통하여 일 최고기온의 반 경험적 산출 시스템을 구축하는데 초점이 맞추어졌다. 회귀식 내에서 EDD가 하나의 독립변수로 추가되었을 때 온도 산출에 어떤 영향을 미치는지도 테스트 되었다. 본 연구에서는 EDD가 회귀식에 추가되었을 때가 그렇지 않았을 때 보다 좋은 상관을 보였고 이는 EDD가 좀 더 정확한 산출을 위해 필요한 자료임을 나타낸다. 진보된 산출시스템을 만들기 위해 본 연구는 3가지 접근을 시도하여 그 결과론 비교하였다. 3가지 접근방법은 다음과 같다: 1) 토지피복을 고려하지 않은 계절별 산출법, 2) 토지피복을 고려한 계절별 산출법, 그리고 3) 계절의 구분이 없는 토지피복 형태별 산출법이다. 세번째 방법이 0.56$^{\circ}C$에서 3.14$^{\circ}C$ 사이의 정확도와 함께 가장 최상의 결과를 보여주었다. 산출결과를 검증하기 위해 가장 정확도가 좋았던 세 번째 산출 시스템에 대한 교차검증을 농경지와 산림지역을 대상으로 수행하였다. 검증결과는 토지 피복의 종류에 관계없이 좋은 결과를 보였다. 따라서 제시된 일 최고기온 산출 시스템은 남한의 대부분 지역에서 적용 가능하리라 사료된다.

• 한국토양비료학회지
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• 제44권5호
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• pp.944-958
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• 2011

Soil hydraulic properties such as hydraulic conductivity or water retention which are costly to measure can be indirectly generated by soil pedotransfer function (PTF) using easily obtainable soil data. The field soil structure description which is routinely recorded could also be used in PTF as an input to reduce the uncertainty. The purposes of this study were to use qualitative morphological soil structure descriptions and soil structural index into PTF and to evaluate their contribution in the prediction of soil hydraulic properties. We transformed categorical morphological descriptions of soil structure into quantitative values using categorical principal component analysis (CATPCA). This approach was tested with a large data set from the US National Pedon Characterization database with the aid of a categorical regression tree analysis. Six different PTFs were used to predict the saturated hydraulic conductivity and those results were averaged to quantify the uncertainty. Quantified morphological description was successively used in multiple linear regression approach to predict the averaged ensemble saturated conductivity. The selected stepwise regression model with only the transformed morphological variables and structural index as predictors predicted the $K_{sat}$ with $r^2$ = 0.48 (p = 0.018), indicating the feasibility of CATPCA approach. In a regression tree analysis, soil structure index and soil texture turned out to be important factors in the prediction of the hydraulic properties. Among structural descriptions size class turned out to be an important grouping parameter in the regression tree. Bulk density, clay content, W33 and structural index explained clusters selected by a two step clustering technique, implying the morphologically described soil structural features are closely related to soil physical as well as hydraulic properties. Although this study provided relatively new method which related soil structure description to soil structure index, the same approach should be tested using a datasets containing the actual measurement of hydraulic properties. More insight on the predictive power of soil structure index to estimate hydraulic properties would be achieved by considering measured the saturated hydraulic conductivity and the soil water retention.

• 응용통계연구
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• 제37권1호
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• pp.1-12
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• 2024

동일한 설명변수 집합에 여러 개의 반응 변수들이 종속되어 있는 경우를 많은 실제 자료에서 볼 수 있다. 특히, 여러 개의 반응변수가 서로 상관관계를 가지고 있으면 각각의 반응변수에 대한 개별적인 분석보다는 반응변수들 사이의 상관관계를 고려한 동시 추정(simultaneous estimation)이 매우 효과적이다. 이러한 다변량 회귀분석에서 최소거리추정량(least distance estimator; LDE)은 반응변수들간의 상관관계를 모형 적합 과정에 반영하여 다차원 유클리드 공간에서 각 훈련 개체와 추정값 사이의 거리를 최소화하도록 회귀계수들을 동시에 추정한다. 뿐만 아니라 최소거리추정량은 이상치에 대한 강건성을 제공한다. 본 논문에서는 다변량 선형 회귀분석에서의 최소거리추정법에 대해 살펴보고, 나아가 효율적인 변수선택을 위한 벌점화 최소거리추정량을 제시하였다. 본 연구에서 제안하는 adaptive group LASSO 벌점항을 적용한 AGLDE 기법은 반응변수들간의 상관관계를 모형 적합에 반영함과 동시에 설명변수의 중요도에 따라 효율적으로 변수선택을 수행할 수 있다. 제안 방법의 유용성은 모의실험과 실제 자료 분석을 통해 확인하였다.

• 한국경영과학회지
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• 제37권4호
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• pp.211-223
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• 2012

This study purposed to evaluate the influences of rival hospitals on the number of patients who visited the a study territory hospital. Spatial analysis technique was used to measure the impact of rival hospitals in study region. Selected hospitals were all medical school affiliated hospitals which were located in Daejeon metropolitan city and Chungchungnamdo. Patient data was collected from the claims data of the study hospital, and the number of inpatient and outpatients who visited the study hospital between January and June in 2008 were calculated on the smallest administrative district, Eup, Myeon, and Dong, in study region. To control the differences of regional characteristics among Eup, Myeon, Dong, socio-economic variables (total population, number of people aged over 65, number of basic livelihood security recipients, distance from the study hospital to the centroid point of each Eup, Myeon, Dong, number of business, and number of employees) were included in analysis model. These variables were collected from the annual year book of city as well as county located in study region. Cluster analysis classified the study region into three groups by using the difference of between th actual number of inpatient/outpatient and the predicted number of inpatient/outpatient in Eup, Myeon, and Dong. Most areas around the rivalry hospitals were categorized into same group. Multiple regression analysis indicated that areas around rivalry hospitals had statistically significantly negative relationship with the number of inpatients and outpatients who visited the study hospital. As the buffer size was increased from 5Km to 10Km, the standardized regression coefficients were decreased. These study results confirmed that rivalry hospitals in region had negative impacts on the performance of hospitals. It suggests that hospitals will require not only to select their location to minimize the effects of rivalry hospitals, but also to establish their strategy to cope with the rivalry's threats in their region.

• 한국국방경영분석학회지
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• 제29권1호
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• pp.88-111
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• 2003

This paper is to suggest strategic options for improving the export performance of the plant and construction industry. The overall objective of this study is to explore the feasibility of a sustained export performance in the plant and overseas construction industry by an analysis of its international competitiveness and technological competence. The empirical work of this study relates to a chosen sample of Korean and non-Korean firms in the plant and construction industry sector. Primary data was collected through a comprehensive questionnaire survey administered to plant and construction firms in twelve countries, including Korea. The actual number of firms for which full information at a sufficient level of disaggregation was obtained was 62, a response rate of 44.6％. Of these, 42 firms were drawn from Korean plant and construction firms and the remaining 20 firms from 11 other countries. The structure of responding firms by industry shows a total of 29 plant exporters and 33 construction firms. Data analysis was carried out using SPSS statistical technique such as Multiple Regression in order to examine the linear relationship among variables. The findings of the study indicate that export success and failure in plant and construction export markets is determined by firm size and by various qualitative variables. The high export volume (export success) of Plant and construction exporters is more strongly influenced by mutual economic cooperation and number of employees than by sales volume and competent knowledge of the plant and construction markets. It was also found that weak political and diplomatic relation between countries, low sales volume and lack of bid experience have an adverse effect and represent serious barriers to exports.

• 한국임상약학회지
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• 제18권1호
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• pp.60-67
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• 2008

This study aimed to compare a microparticle enzyme immunoassay (MEIA) with a liquid chromatography-tandem mass spectrometry (LC/MS/MS) technique for the measurement of tacrolimus concentrations in adult liver transplant recipients, to investigate how the assay choice influenced the population pharmacokinetics of tacrolimus and to identify patient characteristics that affected pharmacokinetic parameters in each assay. Tacrolimus concentrations from 29 liver (n=52 paired-samples) transplant recipients measured by both MEIA and LC/MS/MS were used to evaluate the performance of these methods in the clinical setting. Tacrolimus pharmacokinetics was studied independently using MEIA and LC/MS/MS data in 70 adult patients using a population approach performed with NONMEM. Patient characteristics which influenced pharmacokinetic parameters in each assay were compared. The relation between LC/MS/MS and MEIA measurements was best described by the regression equation MEIA=1.465*LC/MS/MS-1.336 (r=0.91). Multiple linear regression analysis showed significant inverse relationships between assay difference and hematocrit (Hct) (p<0.025) in liver graft recipients. In MEIA, the population estimate of tacrolimus CL/F and apparent volume of distribution (Vd/F) were found to be 10.1 L/h and 226 L, and in LC/MS/MS, 13 L/h and 305 L respectively. Neither patient's age, weight, gender, grafted hepatic weight, albumin concentration, nor markers of liver function influenced tacrolimus CL/F The final model of CL/F was found to be 10.1+(Hct/Hct mean)$^{12.0}$ in MEIA and 13+(1+Hct/578) in LC/MS/MS indicating that CL/F was influenced by hematocrit.

• Journal of Preventive Medicine and Public Health
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• 제39권2호
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• pp.165-170
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• 2006

Objectives : The determination of oxalate in urine is required for the diagnosis and treatment of primary hyperoxaluria, idiopathic stone disease and various intestinal diseases. We examined the possibility of using Fourier transform near-infrared (FT-NIR) spectroscopy analysis to quantitate urinary oxalate. The practical advantages of this method include ease of the sample preparation and operation technique, the absence of sample pre-treatments, rapid determination and noninvasiveness. Methods : The range of oxalate concentration in standard urine solutions was $0-221mg/{\ell}$. These 80 different samples were scanned in the region of 780-1,300 nm with a 0.5 nm data interval by a Spectrum One NTS FT-NIR spectrometer. PCR, PLSR and MLR regression models were used to calculate and evaluate the calibration equation. Results : The PCR and PLSR calibration models were obtained from the spectral data and they are exactly same. The standard error of estimation (SEE) and the % variance were $10.34mg/{\ell}$ and 97.86%, respectively. After full cross validation of this model, the standard error of estimation was $5,287mg/{\ell}$, which was much smaller than that of the pre-validation. Furthermore, the MCC (multiple correlation coefficient) was 0.998, which was compatible with the 0.923 or 0.999 obtained from the previous enzymatic methods. Conclusions : These results showed that FT-NIR spectroscopy can be used for rapid determination of the concentration of oxalate in human urine samples.

• Earthquakes and Structures
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• 제20권1호
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• pp.109-122
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• 2021

Significant progress in the oil and gas industry advances the application of pipeline into an intelligent era, which poses rigorous requirements on pipeline safety, reliability, and maintainability, especially when crossing seismic zones. In general, strike-slip faults are prone to induce large deformation leading to local buckling and global rupture eventually. To evaluate the performance and safety of pipelines in this situation, numerical simulations are proved to be a relatively accurate and reliable technique based on the built-in physical models and advanced grid technology. However, the computational cost is prohibitive, so one has to wait for a long time to attain a calculation result for complex large-scale pipelines. In this manuscript, an efficient and accurate surrogate model based on machine learning is proposed for strain demand prediction of buried X80 pipelines subjected to strike-slip faults. Specifically, the support vector regression model serves as a surrogate model to learn the high-dimensional nonlinear relationship which maps multiple input variables, including pipe geometries, internal pressures, and strike-slip displacements, to output variables (namely tensile strains and compressive strains). The effectiveness and efficiency of the proposed method are validated by numerical studies considering different effects caused by structural sizes, internal pressure, and strike-slip movements.