• Title/Summary/Keyword: Dummy variables

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Workers' Compensation Insurance and Occupational Injuries

  • Shin, Il-Soon;Oh, Jun-Byoung;Yi, Kwan-Hyung
    • Safety and Health at Work
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    • v.2 no.2
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    • pp.148-157
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    • 2011
  • Objectives: Although compensation for occupational injuries and diseases is guaranteed in almost all nations, countries vary greatly with respect to how they organize workers' compensation systems. In this paper, we focus on three aspects of workers' compensation insurance in Organization for Economic Cooperation and Development (OECD) countries - types of systems, employers' funding mechanisms, and coverage for injured workers - and their impacts on the actual frequencies of occupational injuries and diseases. Methods: We estimated a panel data fixed effect model with cross-country OECD and International Labor Organization data. We controlled for country fixed effects, relevant aggregate variables, and dummy variables representing the occupational accidents data source. Results: First, the use of a private insurance system is found to lower the occupational accidents. Second, the use of risk-based pricing for the payment of employer raises the occupational injuries and diseases. Finally, the wider the coverage of injured workers is, the less frequent the workplace accidents are. Conclusion: Private insurance system, fixed flat rate employers' funding mechanism, and higher coverage of compensation scheme are significantly and positively correlated with lower level of occupational accidents compared with the public insurance system, risk-based funding system, and lower coverage of compensation scheme.

The Effect of Urban and Climate Characteristics on Energy Resilience - Focusing on Blackout Time - (도시 및 기후특성이 에너지 회복력에 미치는 영향 - 정전발생시간을 중심으로 -)

  • Lee, DongSung;Moon, Tae-Hoon
    • Journal of Korea Planning Association
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    • v.54 no.4
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    • pp.122-130
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    • 2019
  • The purpose of this study is to analyze effect of climate and urban factors on energy resilience, and to explore policy alternatives to strengthen resilience of energy system. For this purpose, this study used extensive literature review on resilience studies and multiple regression analysis. In this study, blackout time was set as a dependent variable. And the independent variables were divided into climate and urban (robustness, countermeasure capacity) characteristics. As a result of the analysis, in terms of climate characteristics, maximum wind speed and cooling/heating degree-day have statistically significant impact on blackout time. With regard to urban characteristics, number of consumer, ratio of deteriorated housing and coast dummy variables have statistically significant impact on blackout time. And the ratio of government employees and road ratio were found to be the most influencing factors to shorten time taken to restore original level of electricity supply. Based on the study results, several policy suggestions to improve energy resilience were made such as continuous management of vulnerable areas and strengthening disaster response services. This study only considered engineering dimension of resilience. Further studies need to be approached on ecological & social-ecological dimension.

The Effect of U.S. Protectionist Trade Policy on Foreign Ownership: A Study of Korea's Data Set

  • Jung, Hyun-Uk;Mun, Tae-Hyoung
    • Journal of Korea Trade
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    • v.23 no.7
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    • pp.83-95
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    • 2019
  • Purpose - This study analyzed the effect of the Trump Government's protectionist trade policies on foreign ownership. Specifically, this study empirically analyzes the hypothesis that foreign ownership will decrease after the Trump Government rather than before the Trump Government. Design/methodology - The hypothesis of this study is based on the expectation that US protection trade policy will negatively affect the profitability of Korean companies. The dependent variable in this study is the foreign ownership ratio, and the independent variable is a dummy variable representing before and after the Trump Government. Multiple regression analysis was performed, including the control variables suggested in previous studies related to foreign ownership. Findings - As a result, foreign ownership increased after the Trump Government rather than before the Trump Government. This study further analyzes whether the main variables affecting foreign investor's decision-making are differences before and after Trump Government. The export ratio, profitability and dividends did not differ before and after Trump Government. However, the level of information asymmetry decreased after the Trump Government than before the Trump Government. This suggests that US protection trade policies do not adversely affect the profitability of Korean companies. However, Korean firms are improving their information environment because US protectionist trade policies can lower profitability and negatively impact capital raising. In this regard, the foreign ownership ratio seems to differ before and after the Trump Government. Originality/value - This study contributes in that it presents data that US protectionist policies can affect Korean corporate governance. This study has implications from the short-term analysis of US protection trade policy.

Risk Prediction Process for Access to Hazard Workplaces in Construction Sites (건설현장 내 위험작업구역 접근 시 위험도 예측 프로세스)

  • Ha, Min-woo;Cho, Yu-jin;Son, Seok-hyun;Han, Seung-woo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2020.11a
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    • pp.69-70
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    • 2020
  • Accidents in the construction industry are very high compared to other industries, and the number is also increasing steeply every year. Relevant studies were limited for solving the problems. The purpose of this study is to develop a comprehensive risk prediction process for personnel deployed at construction sites on safety management. First of all, the variables were divided into fixed, real-time and working types variables, and the relevant comprehensive data were collected. Second, the probability of a disaster was derived based on the collected data, and weights for each variable were calculated using the dummy regression analysis method using statistical methodology. Lastly, the resulting weighting and disaster probability equation was constructed, and The Final Risk Calculation Formula was developed. The Final Risk Calculation Formula presented in this study is expected to have a significant impact on the establishment of effective safety management measures to prevent possible safety accidents at construction sites

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Housing Transaction Prices and Depression Experience Rates According to Housing Types Before and After the COVID-19 Pandemic (코로나19 유행 시기 전후 주택유형에 따른 주택실거래가와 우울감 경험률)

  • Kangjae Lee;Yunyoung Kim;Keonyeop Kim
    • Journal of agricultural medicine and community health
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    • v.49 no.1
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    • pp.59-70
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    • 2024
  • Objectives: This research analyzed and compared housing transaction prices and depression rates according to housing types before and after the COVID-19 pandemic. Methods: Data on housing transaction prices and depression rates from 2018 to 2022 in 25 districts of Seoul, South Korea, were utilized. Dummy variables were employed to account for potential confounders influencing the relationship between the variables. Statistical analysis was conducted using R, and the relationship between depression rates and housing transaction prices was examined through Ordinary Least Squares (OLS) and panel data regression analysis. Results: The results of OLS and one-way random effects models indicated a significant relationship between apartment (p<.05) and officetel (p<.001) transaction prices and depression. However, detached/semi-detached and row/townhouse transaction prices did not exhibit a significant relationship with depression. Conclusion: It was observed that as apartment and officetel transaction prices increased in Seoul before and after the COVID-19 pandemic, depression rates also increased. Considering that changes in housing prices by housing type in South Korea may impact the mental health of local residents, it is deemed necessary to consider healthy housing and housing prices as comprehensive determinants of mental health.

Development and application of prediction model of hyperlipidemia using SVM and meta-learning algorithm (SVM과 meta-learning algorithm을 이용한 고지혈증 유병 예측모형 개발과 활용)

  • Lee, Seulki;Shin, Taeksoo
    • Journal of Intelligence and Information Systems
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    • v.24 no.2
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    • pp.111-124
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    • 2018
  • This study aims to develop a classification model for predicting the occurrence of hyperlipidemia, one of the chronic diseases. Prior studies applying data mining techniques for predicting disease can be classified into a model design study for predicting cardiovascular disease and a study comparing disease prediction research results. In the case of foreign literatures, studies predicting cardiovascular disease were predominant in predicting disease using data mining techniques. Although domestic studies were not much different from those of foreign countries, studies focusing on hypertension and diabetes were mainly conducted. Since hypertension and diabetes as well as chronic diseases, hyperlipidemia, are also of high importance, this study selected hyperlipidemia as the disease to be analyzed. We also developed a model for predicting hyperlipidemia using SVM and meta learning algorithms, which are already known to have excellent predictive power. In order to achieve the purpose of this study, we used data set from Korea Health Panel 2012. The Korean Health Panel produces basic data on the level of health expenditure, health level and health behavior, and has conducted an annual survey since 2008. In this study, 1,088 patients with hyperlipidemia were randomly selected from the hospitalized, outpatient, emergency, and chronic disease data of the Korean Health Panel in 2012, and 1,088 nonpatients were also randomly extracted. A total of 2,176 people were selected for the study. Three methods were used to select input variables for predicting hyperlipidemia. First, stepwise method was performed using logistic regression. Among the 17 variables, the categorical variables(except for length of smoking) are expressed as dummy variables, which are assumed to be separate variables on the basis of the reference group, and these variables were analyzed. Six variables (age, BMI, education level, marital status, smoking status, gender) excluding income level and smoking period were selected based on significance level 0.1. Second, C4.5 as a decision tree algorithm is used. The significant input variables were age, smoking status, and education level. Finally, C4.5 as a decision tree algorithm is used. In SVM, the input variables selected by genetic algorithms consisted of 6 variables such as age, marital status, education level, economic activity, smoking period, and physical activity status, and the input variables selected by genetic algorithms in artificial neural network consist of 3 variables such as age, marital status, and education level. Based on the selected parameters, we compared SVM, meta learning algorithm and other prediction models for hyperlipidemia patients, and compared the classification performances using TP rate and precision. The main results of the analysis are as follows. First, the accuracy of the SVM was 88.4% and the accuracy of the artificial neural network was 86.7%. Second, the accuracy of classification models using the selected input variables through stepwise method was slightly higher than that of classification models using the whole variables. Third, the precision of artificial neural network was higher than that of SVM when only three variables as input variables were selected by decision trees. As a result of classification models based on the input variables selected through the genetic algorithm, classification accuracy of SVM was 88.5% and that of artificial neural network was 87.9%. Finally, this study indicated that stacking as the meta learning algorithm proposed in this study, has the best performance when it uses the predicted outputs of SVM and MLP as input variables of SVM, which is a meta classifier. The purpose of this study was to predict hyperlipidemia, one of the representative chronic diseases. To do this, we used SVM and meta-learning algorithms, which is known to have high accuracy. As a result, the accuracy of classification of hyperlipidemia in the stacking as a meta learner was higher than other meta-learning algorithms. However, the predictive performance of the meta-learning algorithm proposed in this study is the same as that of SVM with the best performance (88.6%) among the single models. The limitations of this study are as follows. First, various variable selection methods were tried, but most variables used in the study were categorical dummy variables. In the case with a large number of categorical variables, the results may be different if continuous variables are used because the model can be better suited to categorical variables such as decision trees than general models such as neural networks. Despite these limitations, this study has significance in predicting hyperlipidemia with hybrid models such as met learning algorithms which have not been studied previously. It can be said that the result of improving the model accuracy by applying various variable selection techniques is meaningful. In addition, it is expected that our proposed model will be effective for the prevention and management of hyperlipidemia.

A Study on the Determinant of Korean Fisheries Export to ASEAN (한국의 대ASEAN 수산물 수출결정요인에 관한 연구)

  • Lin, Xuemei;Kim, Ki-Soo
    • The Journal of Fisheries Business Administration
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    • v.47 no.2
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    • pp.15-32
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    • 2016
  • The Association of Southeast Asian Nations(ASEAN) has been the most essential organization in Asia. In spite of the world economic crisis, Southeast Asian countries have shown fast economic growth since 2000, and they have been actively expanding investments and trades especially with major countries. Research on competitiveness in ASEAN market has spawned an increasingly large literature, but empirical research on the determinants of Korea's export to ASEAN is limited. The purpose of this study is to draw out the determinant of Korean fisheries export to ASEAN by carrying out a panel analysis. For achieving such a purpose, pooled OLS, Hausman Test, Fixed Effect, Random Effect are performed. The last 20 years' data over the period of 1995 to 2014 concentrated on the ASEAN 6 countries such as Indonesia, Malaysia, Philippine, Singapore, Thailand, Vietnam is used in this study. Amount of aquatic products export to ASEAN is used as the dependent variable; real exchange rate, real GDP, relative price level and GDP per capita are used as the explanatory variables and FTA as dummy variable. Empirical results show that fixed-effect analysis is the best model among all the models. As the fixed effect model shows, real exchange rate, real GDP, GDP per capita and dummy variable(FTA) play positive and statistically significant roles in fisheries export to ASEAN, while price variable plays a negative and statistically significant role to the dependent variable.

An Adaptive Synchronization by Analyzing the Delay Time of Media (미디어 지연시간 분석에 의한 가변적 동기화)

  • Seo, Yeong-Geon;O, Hae-Seok;Sim, Jong-Chae;Kim, Ho-Yong;Kim, Hyeon-Ju
    • The Transactions of the Korea Information Processing Society
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    • v.4 no.11
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    • pp.2801-2811
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    • 1997
  • This thesis Proposes a media synchronization mechanism for video conferencing system by analyzing a variation of the delay time of media. Using this mechanism, this thesis analyzes the media traffics and determines the values of external variables important on waiting time. This system uses some dummy streams to get the time. When two hosts are initially connected, they change the dummy streams by which a logical time of the sender may be extracted. The time presenting a media stream is a sum of base time, logical time and the waiting time. At this time, for the purpose of optimally adjusting the waiting time, this mechanism uses the rate of updating the waiting time and the sampling unit of media. These values are acquired by analyzing the waiting times, the delay rates and the delayed arrival times.

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The Effect of the Auditor Designation System on the Efficiency of the KOSDAQ IPO Market (감사인지정제도가 KOSDAQ IPO 시장의 효율성에 미치는 효과)

  • Jin-Hwon Lee;Kyung-Soon Kim
    • Asia-Pacific Journal of Business
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    • v.14 no.3
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    • pp.167-186
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    • 2023
  • Purpose - The purpose of this study is to empirically investigate whether the auditor accreditation system for IPO firms improves the efficiency of the KOSDAQ IPO market. To verify the effectiveness of the auditor designation system, we time series compare four measures of IPO firms (earnings management, long-term stock performance, change in operating performance, and possibility of delisting). Design/methodology/approach - We test the hypothesis through event research method and regression analysis. Specifically, the dependent variables of the regression model are discretionary accruals in the year of IPO, 36-month holding period excess return after IPO, change in operating performance for 3 years after IPO, and dummy variable for delisting. And the explanatory variable is a dummy variable that separates the period before and after the implementation of the auditor designation system. Findings - We find that earnings management and delisting risks decreased more in the period after the implementation of the auditor accreditation system than in the previous period. In addition, we find that long-term stock performance and operating performance after IPO increase further after the implementation of the auditor accreditation system. Research implications or Originality - Overall, the results of this study suggest that the implementation of the auditor accreditation system for IPO firms contributes to improving market efficiency in the KOSDAQ market, where information asymmetry is high. Our study differs from previous studies in that it demonstrates the effectiveness of the auditor designation system using various measures.

Models for Estimating Yield of Italian Ryegrass in South Areas of Korean Peninsula and Jeju Island

  • Peng, Jing Lun;Kim, Moon Ju;Kim, Byong Wan;Sung, Kyung Il
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.36 no.3
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    • pp.223-236
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    • 2016
  • The objective of this study was to construct Italian ryegrass (IRG) dry matter yield (DMY) estimation models in South Korea based on climatic data by locations. Obviously, the climatic environment of Jeju Island has great differences with Korean Peninsula. Meanwhile, many data points were from Jeju Island in the prepared data set. Statistically significant differences in both DMY values and climatic variables were observed between south areas of Korean Peninsula and Jeju Island. Therefore, the estimation models were constructed separately for south areas of Korean Peninsula and Jeju Island separately. For south areas of Korean Peninsula, a data set with a sample size of 933 during 26 years was used. Four optimal climatic variables were selected through a stepwise approach of multiple regression analysis with DMY as the response variable. Subsequently, via general linear model, the final model including the selected four climatic variables and cultivated locations as dummy variables was constructed. The model could explain 37.7% of the variations in DMY of IRG in south areas of Korean Peninsula. For Jeju Island, a data set containing 130 data points during 17 years were used in the modeling construction via the stepwise approach of multiple regression analysis. The model constructed in this research could explain 51.0% of the variations in DMY of IRG. For the two models, homoscedasticity and the assumption that the mean of the residuals were equal to zero were satisfied. Meanwhile, the fitness of both models was good based on most scatters of predicted DMY values fell within the 95% confidence interval.