• Journal of Korean Society of Transportation
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• v.21 no.2
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• pp.107-118
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• 2003

Highway Capacity Manual (HCM) provides an analytical delay estimation model to assist the evaluation of traffic at a signalized intersection. The model revised and included in the HCM published in the year 2000 reflects the results of recent studies and is utilized in various fields of transportation studies. For the implementation of the model in the case of permitted left turns, the HCM supplement provides a computational procedure to adjust the saturation flow rate of permitted left toms. The model however, is originally designed for a protected movement and thus underestimates the delay of permitted left turns due to its difference right-of-way nature. This document describes (1) a review of the theoretical background of the HCM delay estimation model, (2) problems embedded in the model for the delay estimation of permitted left turns, (3) a proposed model developed in this study to improve the delay estimation for permitted left turns and (4) a set of verification tests. In order to reflect various traffic and control conditions in the test, simulation studies were performed to by using the field data based on 120 different permitted left-turn scenarios. Comparison studies conducted between sets of delays estimated by the HCM and the proposed models against a set of the CORSIM delays and showed that the proposed model improved the estimation of the permitted left-turn delays. The explanatory variable of the relationship between the HCM delay and the simulation delay was 0.47 and the one between the delay estimated by the proposed model and the simulation delay was 0.77.

• Journal of Technology Innovation
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• v.20 no.3
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• pp.57-91
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• 2012

This paper investigates determinants of litigation success in the two distinctive types of patent litigations, ex-parte and inter-parte cases, which are brought in the process where a filed application becomes a valid patent right. We regress winning rates of patent applicants on the characteristics of firms, trials, patent lawyer, and patent itself, using a probit model with sample selections. The paper finds that the relative suit rate of a firm, time to be sued, changes of patent agents by applicants, and multiple agents among explanatory variables affect ex-parte reexamination and in-parte post-grant patent trials differently in the point of average marginal effects. These variables lower the probability of applicant's victory in the ex-parte cases, while they raise the probability in the inter-parte trials. However, the experience that agents represent applicants is a winning rate-increasing factor both in inter-parte and ex-parte reexamination, unexpectedly. This result cannot be applied to the entire domain of the variable, since sample selection effects are reflected in the result. The number of claim increases the winning probability of the applicant in the both types of patent litigations. This study has some limitations because it ignores the information on the legal person to which a patent agent belongs, and confined agent's experience to patent filing. We leave it future studies to investigate the effects of lawsuit experience of patent agent, and those of characteristics of the law firm to which individual patent lawyer is affiliated.

• Journal of the Korean association of regional geographers
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• v.9 no.1
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• pp.86-96
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• 2003

The purpose of this paper is to explore the relationship between central city and suburban areas. In particular, we examine the relationship of construction activities in suburban areas with construction activities in central city. That is because if the construction activities in central city are correlated with those in suburban areas, the economic trends in those two parts would become interdependent. The construction permit data in 114 Metropolitan Statistical Areas (MSAs) for the past 11 years are used as a central explanatory variable of influencing the relationship, as construction permits issued would reflect population growth, economic growth and housing price in certain area. The main findings of our analysis are as follows. First, MSAs classified as showing high population growth has higher correlation between central city and suburban area than MSAs showing low population growth rate except for only office construction. However, there is little difference in correlation characteristic by the size of MSA Second, most of the MSAs show little causality between the central city and suburban area in lagged situation. Therefore, it is hard to say that the past trend of construction activity in central city reflects in direct the future trend of construction activities in suburban area.

• Journal of Educational Research in Mathematics
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• v.23 no.4
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• pp.467-490
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• 2013

Correlation is a basic statistical concept which is necessary for understanding the relationship between two variables when they change values. In the middle school curriculum of Korea, only informal definition of correlation is taught with two-way data representations such as scatter plots and contingency tables. In this study, we investigated Korean high school students' understanding of correlation using a test consisting of 35 items about interpretation of scatter plot, contingency table, and text in realistic situation. 216 students from a high school in Seoul took the test for 20 minutes. From the results, we could observe the following: First, students did not have right criteria for determining the strength of correlation presented in scatter plots. Most of students could determine if there is correlation/no correlation and if the correlation is positive/negative by seeing the data presented in scatter plots. However, they did not judge by the closeness to the regression line but rather judged by the closeness between data points. Second, when statements about comparing the strength of correlation in the context of real life situation were given in text, the students had difficulty in understanding the distribution-related characteristic of the bi-variate data. Students had difficulty in figuring out the local distribution characteristic of data, which cannot be guessed merely based on the expression 'The correlation is strong' without statistical knowledge of correlation. Third, a large number of students could not judge the association between two variabels using conditional proportions when qualitative data are given in 2-by-2 tables. They made judgement by the absolute cell count and when the marginal sum of two categories are different for explanatory variable they thought the association could not be determined. From these results, we concluded that educational measures are required in order to remove such misconceptions and to improve understanding of correlation. Considering that the current mathematics curriculum does not cover the concept of correlation, we need to improve the curriculum as well.

• Journal of Service Research and Studies
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• v.10 no.1
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• pp.55-67
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• 2020

Fine dust has recently become one of the greatest concerns of Korean people and has been a target of considerable efforts by governments and local governments. In the academic world, many researches have been carried out in relation to fine dust, but the research on the economic field has been relatively few. So we wanted to know how fine dust affects the economy. Big data of PM10 concentration for fine dust and fine dust theme stock price were collected for five years from 2013 to 2017. Regression analysis was performed using the linear regression model, the generalized least squares method. As a result, the change in the fine dust concentration was found to have a effect on the related theme stocks' price. When the fine dust concentration increased compared to the previous day, the fine dust theme stocks' price also showed a tendency to increase. Also, according to the analysis of stock price change from 2013 to 2017 based on fine dust theme stocks, companies with large regression coefficients were changed every year. Among them, the regression coefficients of Monalisa were repeatedly high in 2014, 2015, 2017, Samil Pharmaceutical in 2015, 2016 and 2017, and Welcron in 2016 and 2017, and the companies were judged to be sensitive to the concentration of fine dust. The companies that responded the most in the past 5 years were Wokong, Welcron, Dongsung Pharmaceutical, Samil Pharmaceutical, and Monalisa. If PM2.5 measurement data are accumulated enough, it would be meaningful to compare and analyze PM2.5 concentration with independent variables. In this study, only the fine dust concentration is used as an independent variable. However, it is expected that a more clear and well-explained result can be found by adding appropriate additional variables to increase the explanatory power.

• The Journal of the Korea Contents Association
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• v.18 no.1
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• pp.196-209
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• 2018

This study is founded on banks' profitability factors. Unlike the previous study in terms of diversification of the banks' funding structure, this research performs multiple regression analysis during the entire period and examines the comparative analysis of before and after the financial crisis. the study establishes hypotheses by using the wholesale funding ratio as a key focus variable with 8 explanatory variables and the operating profit on assets as a profitability index. The Loan-deposit rate gap, the Number of stores and the Non-performing loan ratio prove to be a significant profitability factor for all periods of time. Korean banks are also more profitable when their the Loan-deposit rate gap get bigger and the Number of stores grows. The wholesale funding ratio is analyzed to have no statistically significant effect on the profitability of banks. Rather than being influenced by macroeconomic indicators, it is indicated that the situation of individual banks and other financial environments have been affected. And banks increase profitability as banks increase their loan after the financial crisis. The empirical analysis shows that profitability factors have periodical distinctions, and in this aspect, this research has implications. The study needs to be expanded to cover the entire domestic banking sector, in consideration of the profitability of the banking industry in the future.

• Journal of Digital Convergence
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• v.18 no.1
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• pp.257-263
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• 2020

This study was conducted to improve the quality of National Health Policy by analysing the effects of sociodemographic characteristics, Medical institutions characteristics and characteristics of Admission-Discharge on the length of stay in hospital for schizophrenic patients from the data of Health Insurance Review & Assessment Service. The subjects were 4,692 patients who were diagnosed with schizophrenia as main diagnosis from the data records of HIRA-NIS 2016. Regression analysis was performed to evaluate the effect on the length of stay. Sociodemographic characteristics, hospital characteristics and characteristics of Admission-Discharge were used as explanatory variables and length of stay in hospital was used as a dependent variable. The result of study showed that female, age, medical aid, the kind of hospital, gangweon-do and with mental disease were found to be the factors that affect the length of stay. The significance of this study is to use the public data for evaluating factors that affect the length of stay in hospital for schizophrenic patients. But this study did not consider disease severity, so further study is needed for evaluation of the effects of factors on the length of stay according to disease severity.

• Management & Information Systems Review
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• v.36 no.3
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• pp.113-130
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• 2017

This study examines the effect of direct investment in Asia on firm value for nonfinancial firms listed on KRX between 2006 and 2015. We also explore whether the mediating effects of cashholdings the relationship between direct investment in Asian markets and corporate value. Recently, companies are increasing their cash holdings for risk management. Cashholdings are causing agent problems, which has a negative impact on corporate value. In this case, when the company conducts active investment activities such as foreign direct investment, it is possible to supply the appropriate funds in a timely manner, thereby cashholdings increase the possibility of success of foreign direct investment and alleviate the agent problem of cash holdings. For the analysis, the number of directly invested firms in Korean listed firms is used as the explanatory variables for the Chinese and Vietnamese markets where foreign direct investment is the most active, and cash holding is set as the moderating variable. As a result, direct investment in China and Vietnam showed a positive (+) relationship with firm value, and cashholdings have a positive the relationship between foreign direct investment and firma value. The implications of this paper are as follows. First, it is suggested that the direct value of direct investment can be enhanced the relationship between direct investment and firm value in Asia. In addition, it can be suggested that cash holdings play a role of effective investment supply in firms that implement foreign direct investment, positively affecting corporate value.

• Journal of the Korea Society of Computer and Information
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• v.16 no.7
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• pp.183-190
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• 2011

Loan amount of housing mortgage is composed of various factors. This study paper studies focuses on estimating the determinants of a loan amount of housing mortgage. The region for analysis consist of seven groups, that is, metropolitan city (such as Busan, Daegu, Incheon, Gwangiu, Daejeon, Ulsan.) and Seoul. Analyzing period be formed over a 45 time points(2007. 01.~ 2010. 09). In this paper the dependent variable setting up loan amount of housing mortgage, explanatory(independent) variables are composed of the consumer price index, unemployment rate, average monthly household income per household, expenditure rate of health care, composite stock price index and overdue rate of household loans for commercial bank. In looking at the factors which determine loan amount of housing mortgage, evidence was produced supporting the hypothesis that there is a significant positive relationship between the consumer price index and unemployment rate. The study also produced evidence supporting the view that there is a significant negative relationship between expenditure rate of health care. The study found that average monthly household income per household, expenditure, composite stock price index and overdue rate of household loans for commercial bank were not significant variables. The implications of these findings are discussed for further research.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5692-5699
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• 2011

This study aims to determine potential differences in self-perceived oral health levels between blue-collar and white-collar workers. It is based upon questionnaire survey data dating from Mar. 1 to 30, 2011. All the data collected from 200 blue-collar workers and 100 white-collar worker was analyzed using statistical tools like SPSS ver. 19.0. Self-perceived oral health levels were analysed across three sub-factors - physical, psycho-social, and psychological factors - which were confirmed through factor analysis. The psycho-social factor was statistically significant for age and shift work. Self-perceived oral health levels across the three factors were quantitatively correlated except for psychological factors in blue-collar workers. The study found that occupational group affects workers' self-perceived oral health level. The explanatory power of these 4 variables total 51% in blue-collar group. In case of white-collar group, it was found one variable total 30%. Since oral health levels differ between blue-collar and white-collar workers, oral health promotion projects should differentiate between the two groups, and workers with an interest in their tooth for the prevention, yet negligent act because it will keep your personal oral health care in the prevention-oriented oral health promotion.