• Journal of Environmental Impact Assessment
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• v.21 no.6
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• pp.917-925
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• 2012

In this study, we report the runoff characteristics of pollutants for Tamjin A and B watershed in Tamjin river basin using statistical analysis, such as correlation analysis and regression equation. Flow rate and water qualtiy data collected from 2 sampling sites(Tamjin A and B watershed) during 3 years(2009~2011) were analyzed for biochemical oxygen demand(BOD), total nitorgen(TN), total phosphorus(TP) and suspended solid(SS). The results showed that strong correlations were observed between flow rate and SS in Tamjin A, while weak correlations were observed among the BOD, TN, and TP. In Tamjin B, strong correlations were observed among the flow rate, SS and T-P except BOD and TP. Meanwhile, the values of $R^2$ for regression equations between flow rate and pollutants load were greater than 0.7. Results of these statistics indicated that there was a good agreement between flow rate and pollutants load. Also, the flow rate exponents of regression equations for BOD, TN, and TP were smaller than 1 in Tamjin A. In Tamjin B, flow rate exponents of regression equation for BOD and TP were smaller than 1. These results indicated that concentrations of BOD, TN, TP in Tamjin A and concentrations of BOD and TP were decreased as the flow rate was increased. This means that rater than nonpoint sources, point sources affect BOD, TN and TP in Tamjin A and BOD and TP in Tamjin B.

• Journal of the Korean Statistical Society
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• v.35 no.1
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• pp.105-114
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• 2006

In this paper we propose a simple and computationally attractive difference-based variance estimator in nonparametric regression models with multivariate predictors. We show that the estimator achieves $n^{-1/2}$ rate of convergence for regression functions with only a first derivative when d, the dimension of the predictor, is less than or equal to 4. When d > 4, the rate turns out to be $n^{-4/(d+4)}$ under the first derivative condition for the regression functions. A numerical study suggests that the proposed estimator has a good finite sample performance.

• The Korean Journal of Cytopathology
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• v.18 no.1
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• pp.13-19
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• 2007

An aim of this study was to evaluate an effect of misinterpretation of pregnancy related cellular changes on the postpartum regression rate of abnormal cervical smears in pregnancy. A series of 265 cases with abnormal cervical smears in pregnancy were selected from a database of cervical smear results. The selected cases were classified as regression, persistence, and progression based on the results of postpartum cervical smears and histology. Of the selected cases, 162 cases were classified as regression and the postpartum regression rate was 61.1% (162/265). We reviewed abnormal cervical smears in pregnancy these cases. The primary cytologic diagnoses of these cases were ASCUS (118 cases), AGUS (2 cases), ASCUS/AGUS (1 case), LSIL (25 cases), LSIL R/O HSIL (2 cases), and HSIL (14 cases). With information of the pregnacy, we identified decidual cells in 24 cases, but cells identified by the Arias-Stella reaction and trophoblasts were not found. Sixteen cases out of 162 cases were reclassified as a pregnancy related change rather than an abnormal. Desidual cells were considered as ASCUS in 15 cases and as LSIL in one case. The revised postpartum regression rate was 55.5%(147/265) and was lower than the original. Consequently, misinterpretation of the pregnancy related cellular changes has an effect on a rise of the postpartum regression rate of the abnormal cervical smear in pregnancy. Pathologists may diagnose pregnancy related cellular changes as abnormal findings if they do not have information regarding the pregnancy. Therefore, clinical information of pregnancy and knowledge about the pregnancy related cellular changes are essential to prevent misinterpretation.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.71-78
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• 2007

An experimental investigation was conducted to clarify the combustion characteristics of Polyethylene-GOX(PE-GOX) hybrid motor using a single-port fuel grain configuration. Data from the experiments were analyzed to evaluate the length-averaged regression rate of PE-GOX propellants. Based on the existing theories, the empirical regression rate formulas provided from Marxman[3,4] and Altman[14] showed good concordance with the PE-GOX experiments. The accuracy of the regression rate was then evaluated and compared with the measured one. As a result, Marxman's model was somewhat more precise than Altman's model in these experiments. Moreover, the consideration of the empirical regression rate showed that O/F ratio has minor variation due to the quasi constant inflow of the fuel during motor firing.

• East Asian Journal of Business Economics (EAJBE)
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• v.3 no.4
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• pp.9-15
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• 2015

The exchange rate is a very important macro variable that has influence on the whole economy and has, therefore, been the topic of many discussions amongst policymakers, academics and other economic agents. The issue of whether to have a fixed, pegged or floating exchange rate regime was highly debated during the 1970s. The purpose of this paper is to investigate what factors determine the exchange rate in Somalia. Quantitative research methodology has been employed to develop regression model using time series data for the period of 12 years. The regression model has been developed based on Quantity theory of money, purchasing power parity and uncovered interest rate parity theory. Somalia is on the countries where the highest exchange rate volatility exists; for example in 2012, the rate jumped 29% percent and two weak later dropped 21%, when Turkish humanitarian aid agencies injected the market a lot of U.S dollar. Based on my study using regression model for time series data of 12 years, the four factors are mainly attributable for the exchange rate volatility of Somalia; these factors include the balance of payment, inflation rate, money supply (mostly come from remittance and NGOs) and Bank profits.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.323-326
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• 2005

In this study, experimental studies were performed the combustion characteristics of end- burning hybrid propulsion system. PMMA, PE were used as fuel and gas oxygen as oxidizer. The regression rate depend on oxidizer flow rate also on thermodynamic properties of fuel. as result, empirical formula for regression rate was deduces with oxidizer flow rate and mass transfer coefficient B number.

• 중국학논총
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• no.67
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• pp.157-177
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• 2020

The rapid change in the university environment due to the decrease in the school-age population calls for enhancing the competitiveness of China-related departments. In this paper, the university's competitiveness and dropout rate were studied in combination with various factors such as geographical location of Chinese-related departments set up at national universities, convergence with other departments, competition rate for entrance exams, scholarships, and employment rate that have a comprehensive impact on student satisfaction. In particular, the dropout rate presented research results that could help universities strengthen their competitiveness in China-related departments, such as by differentiating customized academic strategies according to the atmosphere of elimination through multiple regression analysis and quantile analysis. We hope this thesis will be the basis for policymaking and judgment in China-related departments.

• Journal of Environmental Health Sciences
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• v.7 no.1
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• pp.9-20
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• 1981

This study was performed to determine the correlationship between temperature and overall removals of BOD, SS and to demonstrate the effect of temperature on treatment performance. These data for a period from February 1, 1977 to January 31, 1980 were obtained from the Cheong-Gye Cheon Sewage Treatment plant. The results of correlation and stepwise multiple regression analysis were as follows. 1) Secondary effluent BOD and SS showed negative correlationship with water temperature, with correlation coefficient of -0.1710, and -0.1654 respectively. 2) Correlation coefficient of BOD, SS removal rate and water temperature were 0.1823 and 0.0429 respectively. 3) Regresion equation for estimate of BOD removal rate was as follows $\widehat{Y}_1$ (BOD removal rate)=63.9994+0.5442X(water temperature). And BOD removal rate showed non significant change according to the water temperature. 4) Regression equation for estimate of SS removal rate was as follows $\widehat{Y}_2$ (SS removal rate)=61.6881+0.1514X(Water temperature). And SS removal rate showed non significant change according to the water temperature. 5) According to the Stepwise Multiple Regression analysis, water temperature ranked second order in the BOD removal rate estimation and the equation was as follows $\widehat{Y}_1$ (BOD removal rate)=69.7398+0.2665 $X_1$ (Primary effluent BOD)+0.3562 $X_2$ (Water temperature)-0.0122 $X_3(Flow)+4413.271X_4$ (Organic Loading).

• Health Policy and Management
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• v.27 no.4
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• pp.296-303
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• 2017

Background: This study purposed to analyze regional factors related to gastric cancer screening rate provided by national cancer screening program in Korea. Methods: The unit of analysis was administrative districts of si gun gu level. Dependent variable was regional gastric cancer screening rate provided by national cancer screening program, and regional variables were selected to represent the regional characteristics such as demographic, health behavior and status, socioeconomic, and health resource. Tobit regression was applied for the analysis. Results: Analysis results showed that gastric cancer screening rate was varied depending on regions from 47.8% to 69.1%. Tobit regression showed that gastric cancer screening rate had negative relationships with smoking rate, financial independence rate, and National Health Insurance premium per capita. And regional gastric cancer screening rate had positive relationships with sex ratio and number of gastric cancer screening center. Conclusion: Regional characteristics should be considered in establishing regional policies for increasing the gastric cancer screening rate.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.3
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• pp.113-118
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• 2011

It is not easy to predict the shrinkage rate of a plastic injection mold in its design process. The shrinkage rate should be considered as one of the important performances to produce the reliable products. The shrinkage rate can be determined by using the CAE tools in the design produces. However, since the analysis can take minutes to hours, the high computational costs of performing the analysis limit their use in design optimization. Therefore this study was carried out to presume for mutual relation of analysis condition to get the optimum average shrinkage by regression analysis. The results shown that coefficient of determination of regression equation has a fine reliability over 87% and regression equation of average shrinkage is made by regression analysis.