• Journal of Preventive Medicine and Public Health
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• v.40 no.6
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• pp.495-504
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• 2007

Objectives : This study attempts to show how studies using non-experimental data can strengthen causal inferences by applying propensity score and instrumental variable methods based on the counterfactual framework. For illustrative purposes, we examine the effect of having private health insurance on the probability of experiencing at least one hospital admission in the previous year. Methods : Using data from the 4th wave of the Korea Labor and Income Panel Study, we compared the results obtained using propensity score and instrumental variable methods with those from conventional logistic and linear regression models, respectively. Results : While conventional multiple regression analyses fail to identify the effect, the results estimated using propensity score and instrumental variable methods suggest that having private health insurance has positive and statistically significant effects on hospital admission. Conclusions : This study demonstrates that propensity score and instrumental variable methods provide potentially useful alternatives to conventional regression approaches in making causal inferences using non-experimental data.

• Environmental and Resource Economics Review
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• v.20 no.3
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• pp.531-565
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• 2011

All previous studies analyzing multivariate time series data of EUA (European Union Allowance) price commonly used endogenous variables within the four variables and included the period from April to June of 2006 in the analysis, when the price distortion occurred. This study uses graph theory and structural vector error correction model (SVECM) to analyze the daily time series data of the EUA (European Union Allowance) price. As endogenous variables, five variables are considered for the analysis, including prices of crude oil, natural gas, electricity and coal in addition to carbon price. Data period is Phase 2 period (April 21, 2008 to March 31, 2010) to avoid the EUA price distortion of Phase 1 period (2005~2007). Further, the monthly data including the economic variables as endogenous variables are analyzed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.2
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• pp.523-531
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• 2016

This paper studies the empirical relationship between various privacy protection measures and personal information invasion experience of firms and individuals using rich and heterogeneous survey data. By analyzing PSM models. we get the following results: first, the treatment group which have more technical measures and/or IS investment tends to experience more privacy invasion than the control group which have less of them. second, the reverse causality, that is firms and individuals with more experience of privacy invasion tends to take more measure for personal information protection, is found to exist. From these result, we discuss proper privacy policies implications in respects of attackers benefits and individual irrationality.

• 한국경영정보학회:학술대회논문집
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• 2008.06a
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• pp.585-589
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• 2008

LCD (Liquid Crystal Display)는 디지털 기기의 주요 구성 요소이며, 모든 크기의 FPD (Flat Panel Display) 시장에서 지배적인 시장점유율을 보인다. 그러나 많은 전문가들은 LCD 산업이 수년 내에 OLED (Organic Light Emitting Diodes), 3차원 디스플레이, 플렉서블 디스플레이와 같은 차세대 디스플레이 기술의 강력한 도전에 직면할 것이라고 예상한다. 이러한 경쟁환경에서 LCD 산업이 살아남기 위한 방안으로 본 연구에서는 LCD 산업의 경쟁력의 원천을 밝혀내고, 이를 극대화하는 전략적 방향을 제시한다. 이를 위해 먼저 LCD 산업구조와 가치사슬을 분석하여 LCD 산업의 경쟁력을 제고하기 위한 기본적인 전략적 대안을 개발한다. 이 단계에서 얻어진 통찰력을 바탕으로, 인과지도(causal loop diagram)와 시스템 다이나믹스 (system dynamics) 방법론을 활용하여 기존의 LCD 산업구조에서 판매량, 시장점유율 및 이익 등의 핵심 지표에 가장 큰 영향을 미치는 구조적 특징을 규명한다. 또한, 여기서의 다이나믹스 모형을 바탕으로, LCD 제조업자의 관점에서 프로세스 역량을 극대화할 수 있는 전략적 대안을 모색한다.

• The Journal of the Korea Contents Association
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• v.18 no.11
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• pp.611-622
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• 2018

In this study, I was to investigate the trends in research on walking and positioning in Korea and to compare the results of researches on the Visually Impaired and the Non-disabled. I selected 113 papers in order to know the current status of the study for the visually impaired and to suggest future research directions. This study analyzed the general features (publication year, academic journals, number of authors, keywords, research methods, research types, implementation methods, research support, references) and research themes and contents of domestic research on walking and positioning. As a result, there was no an upward trend in number of publications by the Visually Impaired compared to the Non-disabled. In addition, in the case of the non-disabled, Research topics, types of research, implementation include various attempts of location-related technologies, and system development, improvement, stabilization, and accuracy, whereas in the case of the visually impaired, there were focused on development of systems, portable or attachable devices that reflect the characteristics of the visually impaired. There were not many studies on system improvement. Research support also showed that the non-disabled received various research support. Therefore, I suggested the need to continuously develop and improve the research, to diversify research topics and research types, to expand the research scope, to improvement feasibility for the visually impaired.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.2
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• pp.263-277
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• 2020

Children's use of the Internet is growing. Each company collects children's personal information. However, it is also difficult for children to recognize the concept of personal information. In this study, based on the analysis of newspaper children's personal information leakage, we investigated the occurrence of personal information leakage in children through ground theory, one of qualitative research methods used in the social science field. The ground theory is thought to be able to derive a causal relationship by identifying the leakage of children's personal information. As a result of the study, it was collected through the consent of the legal representative, but depending on the situation, the consent process was not performed. Even with the consent, it was found that due to insufficient measure to protect personal information, various situation(criminal damage, anxiety, embarrassment, anger, etc.) occurred the legal representative. As a result, children's personal information collection providers paid fines according to the situation.

• Journal of Service Research and Studies
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• v.6 no.4
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• pp.75-85
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• 2016

Coal can be divided into thermal coal and coking coal. The price of thermal coal is basically affected by demand and supply. However, many other factors with regard to economic condition such as exchange rate, economy growth rate also make an influence on the price. This study is targeted to develop a forecast model for thermal coal price by using System Dynamics Method. System dynamics provides results that better reflect the real world by employing an inter-dependent system of variables. This study found out that 8 factors have important influence on the thermal coal price. Most of the data of the variables were acquired from the Bloomberg Database. The period extends to 2 years and 4 months, from May of 2011 to August of 2013. The causal relations among the variables were acquired by regression analysis

• Journal of the Society of Disaster Information
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• v.13 no.1
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• pp.89-95
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• 2017

The cases of animals unusual behavior have been reported occasionally before a major disaster occurs. Could animals unusual behavior associated with a major disaster occurrence, if so, could we foreknow a disaster occurrence? The purpose of study is to quest an answer through literature reviews on the relation between animals unusual behavior and premonitory symptoms of an earthquake. These empirical studies are classified three parts according as methodological framework; statistical analysis, experimental analysis, observation analysis. The results are simply divided as two, 'animals unusual behavior may be seen as a precursor of pre-disaster phenomena' and 'difficult to see.' A number of studies have been performed abroad, however there is no one in Korea. Most of the studies point out common limitations-difficult to verify the reliability of data, accidentally get and fewer samples of data, difficulty of ensuring appropriate data, etc. That is why more related research with animals unusual behavior and disaster occurrence is needed to validate cause-and-effect relation of animal unusual behavior and pre-disaster phenomena.

• Clinics in Shoulder and Elbow
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• v.15 no.1
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• pp.52-64
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• 2012

Acute traumatic shoulder injuries related to motor vehicle accidents and industrial accident has shown a steep increase recently. In regard to the causal relationship and the previous illness, the rotator cuff tear and SLAP lesion are the mostly debated among shoulder injuries related to trauma. Both the possibility of spontaneous occurrence related to their degenerative etiology and the discordance between the extent of injury and the symptom of the rotator cuff tear and SLAP lesion, make it difficult and obscure to estimate the extent of involvement of accident. Therefore, the Insurance Committee of Korean Shoulder and Elbow Society performed a questionnaire for the shoulder specialists to investigate their criteria about deciding the treatment modalities and SLAP lesion and reviewed literatures regarding the causal relationship between the accident and the rotator cuff tear and SLAP lesion. The committee recommended the diagnostic criteria to judge contribution of the accident on traumatic shoulder injuries, and to offer a guideline for disabilities.

• Korea journal of population studies
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• v.34 no.2
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• pp.135-162
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• 2011

Given the 4 contexts-parents, friends, teachers and community- of adolescents, this research verified the casual relationships between each contextual support and the suicidal impulse, and the gender difference. The 4-year longitudinal data(KYPS) collected from 3,697 adolescents were used in this study. Using the Autoregressive Cross-Lagged Model, the suicidal impulse was consistently present from the 3rd grade in middle school to the 3rd grade in high school with significant stability. Gender differences were founded in the effect of parental support among the 3rd grade in middle school. Also the negative effect of friends' support on the suicidal impulse among the first grade high school students. The effects were more stronger for girls than boys. Previous supports by teachers and community had no significant effects on later suicidal impulses. These results suggest that the study of suicidal impulse needs to examine the complex support system of multiple context layers.