• 한국신뢰성학회지:신뢰성응용연구
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• 제17권1호
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• pp.38-49
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• 2017

Purpose: The purpose of this study is to introduce the assessment model for industrial accidents prevention policy. Methods: 10 years of industrial accidents data are explored through EDA approach. Case control study is tried in order to assess the effectiveness of the measures taken by Korea Safety and Health Agency, Civilian, and 'Ministry of Employment and Labor'. Propensity score matching is used to match the characteristics of the two groups compared, and then case control study is again conducted. Next, logistic and Poisson regressions are used to assess the risk factors. Results: According to case control study involvement of 'Korea Safety and Health Agency' and 'Ministry of Employment and Labor' were not effective, but Civilian was. Propensity score matching leads to the same conclusion. Poisson regression reveals the impact of the risk factors on the industrial accidents. Industrial accidents occur more often as the number of employees grows. Mining, farming, fishing, 'transportation storage and telecommunication' and forestry have a higher level of industrial accidents but service industry has a lower level. It is odd that more involvement of Korea Safety and Health Agency, Civilian, and Ministry of Employment and Labor means more industrial accidents. Conclusion: 'Korea Safety and Health Agency', Civilian, and 'Ministry of Employment and Labor' seem to visit those industries with more industrial accidents.

• KDI Journal of Economic Policy
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• 제39권1호
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• pp.1-18
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• 2017

This paper empirically studies the effect of public procurement on small and medium-sized enterprises (SMEs) in the Republic of Korea using firm-level data. Public procurement, the purchase of goods and services from private firms by the public sector, is regarded as an important policy measure for providing support to firms, particularly SMEs. This study uses establishment-level panel data of the mining and manufacturing sectors from the Korean National Bureau of Statistics (Statistics Korea) and procurement history from the Korean Public Procurement Service to empirically estimate the effects of public procurement on firms' productivity (total factor productivity) and survivability. Using a propensity score matching estimation method, we find that participating firms showed higher productivity than non-participating ones in the control group only for the year of participation, that is, 2009. After two years, in 2011, they exhibited significantly lower productivity. In contrast, establishments that participated in public procurement for SMEs in 2009 were more likely to survive than those that did not do so in 2011. These results can be interpreted as the negative consequences of government intervention. The market's efficiency enhancement is hindered if underserving companies survive owing to government intervention but fail to improve efficiency.

• Journal of Yeungnam Medical Science
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• 제34권2호
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• pp.216-221
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• 2017

Background: This study was conducted to investigate preoperative carcinoembryonic antigen (CEA) as a prognostic factor in colorectal cancer. Methods: Between January 2000 and July 2011, 1298 patients with primary adenocarcinoma colorectal cancer without metastasis, who underwent curative resection were retrospectively identified. The patients were divided into two groups according to serum CEA level at primary diagnosis: a high CEA (HCEA) group (serum CEA ${\geq}6ng/mL$) and a normal CEA (NCEA) group (serum CEA <6 ng/mL). A 1:1 propensity score matching analysis was applied to reduce bias. Finally, 364 patients were enrolled in this study. Matched variables were age, gender, preoperative chemoradiotherapy, tumor site, cell differentiation and pathologic stage. Results: The clinicopathological characteristics of the two groups did not differ significantly difference. The systemic metastasis rate was 16.5% (30/182) and 25.3% (46/182) in the NCEA and HCEA groups, respectively (p=0.039). There were no significant differences in local recurrence or metastatic sites between groups. The 5-year disease-free survival (DFS) rate of the HCEA group was worse than that of the NCEA group; however, there was no significant difference in overall survival between the two groups. Conclusion: Elevated preoperative CEA was related to frequent systemic recurrence and low DFS. Therefore, elevated preoperative CEA could be considered a prognostic factor for worse clinical outcomes in patients with colorectal cancer.

• KDI Journal of Economic Policy
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• 제32권2호
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• pp.27-53
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• 2010

본 논문은 우리나라에서 직업능력 향상을 위한 교육훈련이 개인의 임금에 어떤 영향을 미치는지를 "경제활동인구조사" 자료를 통해 분석한다. 교육훈련의 내생성을 통제하기 위하여 실증분석 방법으로 (1) 고정효과 추정법과 (2) 성향점수 매칭법을 적용한다. 고정효과 추정법(매칭법)의 결과에 따르면, 지난 1년 동안에 이수한 교육훈련으로 인하여 개인의 월평균 임금수준은 평균 2.6~4.7%(7.5~9.8%) 정도 상승한다. 상이한 두 가지 추정방법의 분석 결과를 종합하면, 우리나라에서 직업능력 향상을 위한 교육훈련의 임금 상승효과는 평균 2.6~9.8% 수준인 것으로 추정된다.

• 한국병원경영학회지
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• 제21권4호
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• pp.45-54
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• 2016

The purpose of this study is to identify patient and hospital characteristics with pulmonary tuberculosis and to analyze factors which were influencing length of stay and treatment. The Korean National Hospital Discharge In-depth Injury Survey database from 2006 to 2012 was used for analysis. Study subjects were 4,704 patients and analyzed by using frequency, chi-square and logistic regression through using STATA 12.0. To avoid selection bias, we used propensity score matching. Analysis results show that the length of stay and treatment of pulmonary tuberculosis was different between insurance types. Patients characteristic(female, comorbidity, admission by outpatient department, medical insurance type) and hospital characteristic(500-999 beds, over 1000 beds) significantly influence length of stay. Admission by outpatient department and over 1000 beds are significantly influence treatment. Based on these findings, it is necessary to clarify between length of stay and treatment outcome by medical aids beneficiaries and audit hospitals follow discharge guidelines in pulmonary tuberculosis patients.

• 무역학회지
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• 제44권3호
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• pp.227-252
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• 2019

This study explores the effects of exports on the innovation of Korean firms listed on two Korean stock markets, the Korean Stock Exchange and the Korean Securities Dealers Quotations, between 1999 and 2016. By matching exporting firms to non-exporting ones with propensity score matching, this study accounts for a problem from sample selection bias that may arise from differences in firm-characteristics between the two groups. From the study results, first, both export participation and export volume significantly increase subsequent innovation performance, as measured by the number of patent applications. This result seems to support the "learning by exporting" hypothesis for Korean listed firms. Second, both export participation and export volume narrow innovation scope, proxied as the number of unique International Patent Classification (IPC) codes of the patent applied, the degree to which patents are concentrated in a particular class, and the degree of proximity in the patents. The findings of innovation scope suggest a possible explanation that the learning effect appears in familiar technology fields that firms have previously held, rather than in unfamiliar ones. Third, these results are robust using alternative proxies in the innovation scope, Tobit regressions to consider the non-trivial portion of sample firms with patent applications equal to zeros, and generalized method of moments (GMM) to control for the persistence of innovation measures hearing over years. Finally, the two main results are more pronounced in large firms than in small and medium-sized ones. As for Chaebol firms, however, these results do not appear.

• 한국산업보건학회지
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• 제31권4호
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• pp.367-377
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• 2021

Objectives: Taxi drivers are exposed to various hazards, such as long periods of sedentary work and traffic-related air pollutants. However, studies on the health effects among taxi drivers in South Korea are insufficient. Methods: To assess subclinical hematologic change related to cardiovascular disease among male taxi drivers, we analyzed data from the second Korean National Environmental Health Survey. Fifty-nine taxi drivers and 1,912 controls were included in the analysis. Propensity score matching was performed to adjust for age, body mass index, and urinary cotinine. A total of 295 subjects were matched with 59 taxi drivers. Leukocyte count, platelet count, hematocrit, triglyceride, total cholesterol, HDL cholesterol land total IgE of the taxi drivers were compared with the control groups. Results: Taxi drivers showed significantly elevated blood leukocytes and platelets. Serum total IgE was significantly reduced in taxi drivers. However, blood leukocytes, platelets, and serum total IgE were not significantly correlated with work period among taxi drivers. Conclusions: Regarding the change of the blood leukocyte count, platelet count, and serum total IgE, taxi driving has the possibility to be associated with peripheral inflammation, humoral immunity and cardiovascular risk.

• 농촌계획
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• 제30권1호
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• pp.81-97
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• 2024

This study examines the effects of adopting Information and Communication Technology (ICT) in livestock farm management on farm sales revenue. Using the 2020 Census of Agriculture, Forestry, and Fisheries, a nationally representative data set constructed by Statistics Korea, this study focuses on a sample of 9,020 livestock farms in South Korea. We employ Propensity Score Matching (PSM) methods to address the potential selection bias between 2,076 farms that used ICT for livestock farm management and 6,944 farms that did not. The findings consistently show that the use of ICT significantly increases farm revenue, taking into account the selection bias. The utilization of ICT in livestock farms leads to a higher increase in sales revenue, particularly for farms with greater sales.

• 농촌계획
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• 제30권3호
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• pp.29-35
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• 2024

The Facility Modernization Policy for Improvement of Fruits Quality was implemented to improve the competitiveness of the domestic fruit tree sector, and as a result of analyzing samples of participating and non-participating farmers, it is judged to have contributed to the improvement of high-quality fruit production. As a result of analysis using the propensity score matching method, it was found that the Facility Modernization Policy for apple farms contributed to the improvement of fruit quality such as sweetness and high-quality product ratio. In addition, the fruit tree high-quality facility modernization project was found to reduce working hours by about 30 hours per 10a. In the case of grapes, it contributed to quality improvement, including increased sugar content, and reduced working hours by about 15.5 hours per 10a. This study has a limitation in that the number of samples subject to the survey is not large enough, and because of this, it appears that no statistically significant differences in performance variables such as production per unit area and management costs per unit area were found between participating and non-participating farms.

• 대한지구과학교육학회지
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• 제15권1호
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• pp.117-131
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• 2022

본 연구는 환경교육용 보드게임 디자인 활동을 개발하고, 이 활동이 고등학생들의 환경 개념적 지식, 환경 소양 및 창의 공학적 문제해결성향에 미치는 영향을 조사한 것이다. 환경동아리에 소속된 25명의 고등학고 1, 2 학년 학생들이 연구에 참여 하였다. 보드게임 디자인 활동은 총 10차시 수업으로 공학적 설계에 기반하여 개발되었다. 연구의 주요 데이터는 환경 주제(기후온난화와 생태계 파괴)에 관한 학생들의 지식을 측정하기 위해 실시된 사전-사후 개념도와 환경 소양 측정지 및 창의적 공학적 문제해결성향 측정지이다. 연구 결과 환경교육용 보드게임 디자인 활동을 수행한 후 학생들이 제시한 개념도의 환경관련 단어의 개수가 지식 영역에서 증가한 것을 알 수 있었다. 또한 환경 소양측정지와 창의공학적 문제해결성향 측정지의 평균도 사전에 비해 사후에 유의미하게 증가하였다. 이러한 결과를 통해 보드게임을 활용한 수업 방법이 학생들이 다양한 역량을 기를 수 있도록 돕는다는 것을 알 수 있다. 이와 같이 보드게임과 중등 교육을 접목한 연구는 활성화되어야 하며 이를 현장에 적용하기 위해 현직 교사들의 새로운 교육 방식에 대한 교육과 지원이 필요하다.