• 한국항해항만학회지
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• 제44권5호
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• pp.414-422
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• 2020

In this study, an empirical analysis of 55 ship finance cases executed by a specific ship finance bank from 2009 to 2016 during the recession period was conducted. The purpose of this study was to find the factors affecting changes in the debt performance of Korean shipping companies. The main factors were the loan nature (investment purpose, loan-to-value (LTV), syndicated loans, loan terms, put-option, balloon, and spread), financial nature (total assets turnover, net profit-to-sales ratio, debt ratio, quick ratio, total borrowing, bonds payable to total assets, interest expenses-to-sales ratio, debt service coverage ratio (DSCR), and total assets), and the company nature (company age, chief executive officer's (CEO's) shares, and listing status). In this study, the factors affecting the debt repayment capability of domestic shipping companies (loan nature, financial nature, and company nature) were verified. The credit rating was used to measure the dependent variable, debt repayment ability. The variables of investment purpose, put-option, balloon, and spread in the loan nature, debt ratio in the financial nature, and the CEO's shares and company age in the company nature were found to be significant.

• 한국분무공학회지
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• 제4권2호
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• pp.47-52
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• 1999

The prediction of the critical Reynolds number in the stability curie of liquid jet was mainly analyzed by the empirical correlations and the experimental data through the literature. The factors affecting the critical Reynolds number include Ohnesorge number, nozzle length-diameter ratio, ambient pressure and nozzle inlet type. The nozzle inlet type was divided into two groups according to the dependence of the critical Reynolds number on the length-to-diameter ratio of nozzle. The empirical correlations for the critical Reynolds number as a function of above factors mentioned are newly proposed.

• Communications for Statistical Applications and Methods
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• 제19권5호
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• pp.663-671
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• 2012

In the present study, a combined ratio cum regression estimator is proposed to estimate the population mean of the study variable in the presence of a non-response using an auxiliary variable under double sampling. The expressions of bias and mean squared error(MSE) based on the proposed estimator is derived under double (or two stage) sampling to the first degree of approximation. Some estimators are also derived from the proposed class by allocating the suitable values of constants used. A comparison of the proposed estimator with the usual unbiased estimator and other derived estimators is carried out. An empirical study is carried out to demonstrate the performance of the suggested estimator and of others; it is endow that the empirical results backing the theoretical study.

• 경영과정보연구
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• 제22권
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• pp.1-23
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• 2007

This paper investigates the relationships between exports, firm size, and firm dynamics. It is based on a longitudinal data covering listed firms in the Korean manufacturing industry. We found the stylized fact that the probability that a firm is exporter increases with firm size. A regression model for the determinant of export/sales ratio including dynamic adjustment process is tested on a cross-section sample for the year 2001. Empirical findings suggest that there is a positive and inversely U-shaped relationship between firm size and export/sales ratio, just for basic material and capital good industry. Except for firm size, the hypotheses concerning human capital intensity, physical capital intensity, R&D intensity, and patent are rejected. Using Granger causality test, we found that the rate of growth of total sales influences the change of the export/sales ratio with time lag for medium-sized firms. Finally, some policy implications are presented.

• Current Optics and Photonics
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• 제2권5호
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• pp.413-421
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• 2018

We propose a novel methodology based on the multiplication function to improve the signal-to-noise ratio (SNR) for vibration detection in a phi optical time-domain reflectometer system (phi-OTDR). The extreme-mean complementary empirical mode decomposition (ECEMD) is designed to break down the original signal into a set of inherent mode functions (IMFs). The multiplication function in terms of selected IMFs is used to determine a vibration's position. By this method, the SNR of a phi-OTDR system is enhanced by several orders of magnitude. Simulations and experiments applying the method to real data prove the validity of the proposed approach.

• Geomechanics and Engineering
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• 제20권5호
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• pp.371-384
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• 2020

A settlement prediction method based on shear wave velocity measurements and soil nonlinearity was recently developed and verified by means of centrifuge tests. However, the method was only applicable to heavily overconsolidated soil deposits under enlarged yield surfaces. In this study, the settlement evaluation method was refined to consider the stress history of the sublayer, based on an overconsolidation ratio evaluation technique, and thereby incorporate irrecoverable plastic deformation in the settlement calculation. A relationship between the small-strain shear modulus and overconsolidation ratio, which can be determined from laboratory tests, was adopted to describe the stress history of the subsurface. Based on the overconsolidation ratio determined, the value of an empirical coefficient that reflects the effect of plastic deformation over the elastic region is determined by comparing the overconsolidation ratio with the stress increment transmitted by the surface design load. The refined method that incorporate this empirical coefficient was successfully validated by means of centrifuge tests, even under normally consolidated loading conditions.

• 수산경영론집
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• 제34권1호
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• pp.31-44
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• 2003

The purpose of this study is to investigate empirically interaction among the financing decision, investment decision, and profitability by using 41 fisheries corporations in Korea, and to suggest implications of the empirical results for government's financial policy for fisheries corporations. Sample period is 19 years from 1982 till 2000. This analysis method employs the two stage least squares(2SLS) estimation method. From the results of regression analysis by 2SLS estimation method, the adjusted $R^2$ values were high and the overall F values indicated significant. The empirical results of this study are as follows; (1) determinant factors of capital structure model for fisheries are profitability, firm-size, fisheries investment of total asset, and business risk. As pecking order theory explains, the higher is profitability the lower is debt ratio. The larger firm-size, the higher is debt ratio. The higher is fisheries investment of total asset and business risk, the higher is debt ratio. (2) determinant factors of investment model for fisheries are the change of sales, business risk, and debt ratio. These factors have positive relation to fisheries investment of total asset (3) determinant factors of profitability model for fisheries are fisheries investment of total asset and debt ratio. These factors have negative relation to profitability. On the basis of analysis results, on the government's financial policy for fisheries corporations, I suggests that with interest rate reduction, the government should lend more funds to solve the crisis in the financial structure of the fisheries firms

• 대한교통학회지
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• 제24권4호
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• pp.31-42
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• 2006

본 연구는 도로안전개선사업의 공간적범위 (지점단위/구간단위)에 따른 도로안전시설물의 효과도 비교를 목적으로 한다. 분석자료는 전라북도 지역 국도를 대상으로 사고잦은지점개선사업과 국도17호선 구간안전개선사업 시행도로에 대한 사전 사후 사고자료와 도로 교통특성자료를 이용하였다 경험적베이즈기법(Empirical Bayes ; EB)을 이용한 시설물별 효과도 산정모형을 구축하고, 비교를 위해서는 승산비 (Odds Ratio)를 이용하여 상대효과도 산정기법을 제시하였다. 분석결과 구간사업에서 설치한 안전시설물이 지점단위 개선사업보다 상대적으로 $7.09%{\sim}77.27%$ 안전성을 개선시키는 것으로 나타났다. 사업의 공간적 범위에 상관없이 구간특성을 가지는 시설물인 중앙분리대와 가드레일은 상대효과도가 크지 않게 나타났으나, 대표적인 지점설치 시설물인 갈매기표지나 미끄럼방지포장 등은 구간사업에서 그 상대효과도가 매우 크게 나타나 향후 시설물 설치시 구간측면에서 고려가 필요함을 알 수 있었다. 이와 같은 연구결과를 토대로 보았을 때 향후 안전시설물 설치와 같은 도로안전개선사업은 구간단위 사업이 확대되어야 할 것으로 보인다.

• 한국수자원학회논문집
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• 제54권12호
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• pp.1305-1316
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• 2021

본 연구에서는 과거 추적자실험결과를 이용하여 2차원 횡분산계수에 대한 새로운 추정식을 개발하고 추정식을 이용한 횡 분산계수 산정결과의 정확도를 검증했다. 다수의 추적자실험이 하폭 대 수심비가 50보다 작은 조건에서 수행되었기 때문에 기존 추적자실험결과만을 이용하여 개발한 추정식은 하폭 대 수심비가 50보다 큰 조건의 하천에 적용하는데 한계를 보인다. 따라서 특정 수리조건에 편중된 횡 분산계수 자료로부터 횡 분산계수 추정식을 개발하기 위해 SMOTE (Synthetic Minority Oversampling TEchnique)를 적용하여 기존 자료의 특성을 반영한 새로운 데이터를 생성했다. SMOTE 기법으로 하폭 대 수심비가 50보다 큰 조건에 대한 수리량과 횡 분산계수 데이터를 생성하였으며, ROC (Receiver Operating Characteristic) 곡선으로부터 생성된 데이터의 신뢰성을 검증했다. 새롭게 생성된 데이터를 포함하여 횡 분산계수 추정식을 개발했고, 추정식을 이용하여 계산한 횡 분산계수의 R²(결정계수)를 계산하여 기존 연구에서 제안한 추정식과의 정확도를 비교했다. 그 결과, 본 연구에서 개발한 추정식을 이용하여 계산한 횡 분산계수의 R²가 W/H < 50인 조건에서 0.81, 50 < W/H 인 조건에서 0.92를 나타내어 기존 추정식과 비교하여 향상된 정확도를 나타냈다.

• 대한토목학회논문집
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• 제37권6호
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• pp.989-999
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• 2017

본 연구에서는 분기수로에서 발생되는 에너지손실을 계산하기 위한 손실계수의 경험식을 산정하기 위해 수리모형실험을 수행했다. 수리모형은 유입수로와 90도의 각도를 갖는 두 유출수로로 구성되어 있으며, 유입수로과 유출수로에서 압력수두와 속도수두를 측정하여 분기수로에서 발생되는 에너지손실을 분석했다. 각 측선에서 동수경사선의 변화를 비교한 결과, 수로의 분기점에서 동수경사선이 급격히 하강하여 에너지손실이 분기점에서 발생되었으며, 유량비의 증가에 따라 속도수두의 감소폭이 증가했다. 유량비와 Froude수가 증가함에 따라 유출량이 더 큰 수로에서 수두손실량이 지수적으로 증가하는 결과를 보였으며, 손실계수 또한 증가했다. 반면에, 유출량이 작은 수로에서는 유량비와 Froude수의 증가에 따라 손실계수가 감소하는 결과가 나타났다. 손실계수 계산결과를 이용하여 두 유출수로에서 손실계수 경험식을 제안하였으며, 경험식의 계산오차가 각각 3.91%, 5.19%로 나타났다. 그리고 두 경험식을 이용하여 계산한 총 손실계수를 실험결과와 비교하여 3.62%의 오차가 발생했다.