• Journal of the Korean Data and Information Science Society
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• v.2
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• pp.45-62
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• 1991

In this paper we propose new nonparametric estimators of the survival function using spline function under the progressively random censoring scheme. This sampling scheme is applied in many practical situations such as clinical trials or the life testing problems. We also investigate the behaviors for some estimators in the proposed class and the performance of progressively random censoring scheme through the numerical examples and Monte Carlo simulation.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.43-44
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• 2023

항공기 사고시에 탑승객의 생존성을 제고하기 위한 방법으로 충돌/충격 전, 충격방지자세 Brace Position를 취하도록 하는 것이 전 세계 항공사의 공통적인 안전 매뉴얼이다. 해당 매뉴얼은 1980년대 미국 NTSB에서 항공기 사고를 조사하면서 생존 특성을 연구한 이후 처음 정형화 되었고 이후 현재까지 일반적으로 적용되고 있다. 그러나 허드슨강의 기적으로 불리는 2009년 1월 15일 US Airways 1549편의 비상착수 사고에서 항공기의 큰 구조적인 손상이 없었음에도 불구하고 탑승객 일부가 중상을 입는 결과를 초래하여 이를 계기로 기존의 충격방지자세 적절성을 재검토하여 개선하는 움직임이 있었다. 이에 관련 연구자료를 분석하여 국내 적용 방안을 살피고 또한 추가적인 개선방안을 제시하고자 한다.

• Journal of Korea Society of Industrial Information Systems
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• v.28 no.2
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• pp.1-9
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• 2023

Research using AI and big data is also being actively conducted in the health and medical fields such as disease diagnosis and treatment. Most of the existing research data used cohort data from research institutes or some patient data. In this paper, the difference in the prediction rate of survival and the factors affecting survival between breast cancer patients in their 40~50s and other age groups was revealed using health insurance review claim data held by the HIRA. As a result, the accuracy of predicting patients' survival was 0.93 on average in their 40~50s, higher than 0.86 in their 60~80s. In terms of that factor, the number of treatments was high for those in their 40~50s, and age was high for those in their 60~80s. Performance comparison with previous studies, the average precision was 0.90, which was higher than 0.81 of the existing paper. As a result of performance comparison by applied algorithm, the overall average precision of Decision Tree, Random Forest, and Gradient Boosting was 0.90, and the recall was 1.0, and the precision of multi-layer perceptrons was 0.89, and the recall was 1.0. I hope that more research will be conducted using machine learning automation(Auto ML) tools for non-professionals to enhance the use of the value for health insurance review claim data held by the HIRA.

• The Korean Journal of Applied Statistics
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• v.15 no.1
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• pp.57-71
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• 2002

We introduce three types of exponential survival models, such as simple model, change-point model and finite mixture model in this paper. Among these models, in order to choose the best model, the model choice method is proposed using Gelfand and Ghosh(1998)'s idea. Then to avoid the computational difficulties, data augmentation method (Tanner and Wong, 1987) and Gibbs sampler (Gelfand and Smith, 1990) are employed. Our methodology is applied to both simulated data and Stangl (1991)'s On-impramint Hydrochloride data.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.1
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• pp.12-20
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• 2021

The purpose of this retrospective study was to evaluate the survival rate by comparing Class II restoration using flowable resin composite with stainless steel crown in primary molars. Electronic medical records and radiographs of 1,504 primary molars with proximal caries of 590 patients from June 2015 to August 2019 were analyzed. With the collected data, survival analysis was performed using the Kaplan-Meier method. The 1-year survival rate of flowable resin composite in the primary molar was 98.5%, 3-year survival rate was 87.7%, and mean survival time was 39 months. There was no statistically significant difference between flowable resin composite and stainless steel crown (p = 0.896). Within the limits of this study, Class II restoration using flowable resin composite can be considered a promising option for the treatment of proximal caries in primary molars.

• Industry Promotion Research
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• v.7 no.1
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• pp.1-8
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• 2022

We investigated various types of machine learning methods that can be applied to censored data. Exploratory data analysis reveals the distribution of each feature, relationships among features. Next, classification problem has been set up where the dependent variable is death_event while the rest of the features are independent variables. After applying various machine learning methods to the data, it has been found that just like many other reports from the artificial intelligence arena random forest performs better than logistic regression. But recently well performed artificial neural network and gradient boost do not perform as expected due to the lack of data. Finally Kaplan-Meier and Cox proportional hazard model have been employed to explore the relationship of the dependent variable (t_i, δ_i) with the independent variables. Also random forest which is used in machine learning has been applied to the survival analysis with censored data.

• Korea journal of population studies
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• v.29 no.3
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• pp.159-188
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• 2006

This study attempts to create a longitudinal dataset by linking tdata on the identical individuals across the monthly sample household management lists of the Economically Active Population Survey(EAPS) and the Household Income and Expenditure Survey(HIES). Using the data constructed through such process, the study also tryies to analyze the duration of longitudinal responses and the characteristics of nonrespondents. Between 1998 and 2002, longitudinal response rates had declined to 46% of total EAPS and 34% of total HIES. The fact that nonresponse was not a random phenomenon leads to concerns about the representativeness of the remaining sample. Using Cox's proportional hazard model the study revealed that the duration of longitudinal responses is affected by the ownership of house and the age of the respondent.

• Journal of the Korean Society for information Management
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• v.6 no.1
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• pp.57-70
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• 1989

Computerization of Newspaper productio~~ will lielp reducing a tremendous labor cost that has been a serious element for survival of Newspaper i~tduslry. The purpose of this paper is to en~plrasve a urgent 11ecd for the co~~strrlction of Newspaper database.

• Journal of Convergence for Information Technology
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• v.11 no.8
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• pp.201-206
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• 2021

The aim of this study was to examined the dermatoxicity of ferrous chloride (FeCl2) and the antioxidative effect of Stachys japonica Miq (SJ) extract on FeCl2-induced cytotoxicity. For this study, superoxide anion-radical (SAR)-scavenging and superoxide dismutase (SOD)-like abilities with cell viability were done. FeCl2 showed a significant decrease of cell viability in dose-dependent manner, and it was mid-toxic. The caffeic acid showed a significant increase of cell viability against FeCl2-induced cytotoxicity. In the protective effect of SJ extract on FeCl2-induced cytotoxicity, it showed SAR-scavenging and SOD-like abilities with a significant increase of cell viability. From these results, the cytotoxicity of FeCl2 is correlated with oxidative stress, and SJ extract effectively protected the cytotoxicity of FeCl2 by antioxidative effect. Conclusively, the natural resources like SJ extract may be a useful fundamental materials for the development of an alternative antioxidant.

• The Monthly Diabetes
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• s.261
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• pp.24-26
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• 2011

신장이식은 국내에서 가장 많이 이루어지고 있는 장기이식수술 중 하나이다. 대한이식학회에서 발표한 자료에 따르면(2009년) 국내 신장 이식자의 5년 생존율은 85.6% 로, 최근 면역억제제의 개발에 따라 성공률이 증가하고 있다.