• Journal of the Korean Data and Information Science Society
• /
• v.23 no.4
• /
• pp.627-641
• /
• 2012

We consider a model estimation and model selection methods for the multi-way contingency table data with non-response or missing values. We also consider hierarchical Bayesian model in order to handle a boundary solution problem that can happen in the maximum likelihood estimation under non-ignorable non-response model and we deal with a model selection method to find the best model for the data. We utilized Bayes factors to handle model selection problem under Bayesian approach. We applied proposed method to the pre-election survey for the 2004 Korean National Assembly race. As a result, we got the non-ignorable non-response model was favored and the variable of voting intention was most suitable.

• The Journal of the Korea Contents Association
• /
• v.13 no.9
• /
• pp.227-235
• /
• 2013

This study aims to testify the effect of self-esteem improvement program for elementary school children from single-parent families on their self-esteem and depression. Methods: The research design used in this study was a non-equivalent control group pretest-posttest research design. The participants were divided into two groups, an experimental group(n=11) and a control group(n=13). Data were analysed by using Mann-Whinety U test, Wilcoxon Signed Ranks, Cohen's d with SPSS(PASW)18.0 program. Result: Significant differences were found in scores for self-esteem(z=-2.499, p<.012, ES(d)=0.7) and depression(z=-2.145, p<.032, ES(d)=-0.4) in experimental group. Conclusion: The results indicate that the self-esteem improvement program should be used with elementary school children from single-parent families to help them and to improve their psycho-social adaptation.

• Communications for Statistical Applications and Methods
• /
• v.15 no.3
• /
• pp.353-365
• /
• 2008

The sample size in a clinical trial is determined by the hypothesis, the variance of observations, the effect size, the power and the significance level. Dropouts in clinical trials are inevitable, so we need to consider dropouts on the determination of sample size. It is common that some proportion corresponding to the expected dropout rate would be added to the sample size calculated from a mathematical equation. This paper proposes new equations for calculating sample size dealing with dropouts. Since we observe data longitudinally in most clinical trials, we can use a last observation to impute for missing one in the intention to treat (ITT) trials, and this technique is called last observation carried forward(LOCF). But LOCF might make deviations on the assumed variance and effect size, so that we could not guarantee the power of test with the sample size obtained from the existing equation. This study suggests the formulas for sample size involving information about dropouts and shows the properties of the proposed method in testing equality of means.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.7 no.4
• /
• pp.13-24
• /
• 2008

Real-time traffic data are readily obtainable by traffic surveillance systems of intelligent transportation systems (ITS). Such data greatly support further applications in the field of traffic operations, planning, and safety. However, traffic data should be appropriately processed to fully exploit the benefits of data collection capability. Rather than developing individual data processing techniques, which is major concern of existing studies, this study proposes a novel methodology for evaluating data processing techniques in an integrated manner. Also, a tool for implementing the proposed methodology is developed. Users can extract useful and more reliable traffic data based upon their ultimate purpose of data usage by the evaluation tool developed in this study. Actual freeway traffic data are, as an example, fed into the evaluation tool, and results are discussed.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.468-468
• /
• 2017

최근 기후변화로 인해 수자원 위험요소인 가뭄 및 홍수피해가 증가하고 있으며, 인구증가에 따른 수량감소로 수자원관리가 더욱 어려워지고 있는 실정이다. 효율적인 수자원관리 및 기후변화 대응을 위해 세계 물시장은 점점 증가하고 있으며, 이에 따라 국내기업 또한 해외사업 진출을 추진하고 있으나, 사업에 필수적인 기상, 수문 등 기초자료의 부재로 어려움을 겪고 있다. 본 연구에서는 국내기업의 해외사업 진출 시 필요한 기상, 지형, 수문, 인문 사회 등 기초자료를 제공하는 글로벌 수자원정보제공시스템(Global Water Bank, GWB)을 설계 및 개발하고자 한다. 국내 외 예비타당성보고서 및 국내에서 수집 가능한 국외 정보현황을 분석하여 자료 제공인자를 도출하였으며, 이를 토대로 시스템 내 제공항목을 기상, 지형, 수문해석, 인문 사회, 기후변화 자료로 구분하였다. 해외시장 진출범위를 고려하여 자료의 공간적인 범위를 전지구로 설정하였으며, 전지구 자료의 가용성을 검토하여 제공자료를 구축하였다. 기상자료는 NCDC (National Climate Data Center)의 관측 지점자료와 APHRODITE (Asian Precipitation - Highly-Resolved Observational Data Integration Towards Evaluation) 격자자료를 수집하였으며, 오 결측 자료는 품질검토를 수행하여 보정하였다. 지형자료의 경우 USGS (U.S. Geological Survey)의 DEM, FAO (Food and Agriculture Organization of the United Nations)의 토양도, UMD (University of Maryland)의 토지피복도를 구축하였다. 수문자료는 GRDC(Global Runoff Data Centre)의 관측 지점자료를 수집하였으며, 미계측 지역의 수문자료 구축을 위해 VIC(Variable Infiltration Capacity) 수문모형을 활용하여 $0.5^{\circ}$ 공간해상도의 격자 유출량 자료를 생산하였다. 인문 사회자료로 World Bank의 국가별 통계자료를 수집하였으며, 구축된 각 자료는 GWB 시스템을 통해 제공된다. 시스템의 시범운영을 위해 아시아 지역을 대상으로 GWB- 버전을 개발하였으며, 시범지역 내 관측자료와 비교분석하여 자료의 활용성을 검증하였다. 추후 GWB 시스템은 해외진출 사업 우선지역 선정 근거로 활용될 수 있는 가상수 및 물산업지수 등의 추가정보를 제공하고 타 지역으로 확대적용 예정이다.

• Journal of Korea Port Economic Association
• /
• v.37 no.1
• /
• pp.121-142
• /
• 2021

The purpose of this study is to identify environmental factors affecting manpower utilization of container terminals. 300 questionnaires were distributed to employees working in terminal operators in Busan and Gwangyang port. Based on the results of multiple regression analysis, first, it is proved that technology development, organizational culture and social·external environment have a significant impact on manpower utilization of container terminals. Second, this study found that technology development and social·external environment have a significant impact on manpower utilization of container terminals system. Third, it is found that technology development, social·external environment, safety and security change the composition of the workforce between office and field employees. Forth, the number of workforce is expected to gradually decrease due to technology development. Finally, it is found that technology development, organizational culture, social·external environment and terminal operation have a impact on specialization and training system of human resoures.

• Therapeutic Science for Rehabilitation
• /
• v.8 no.1
• /
• pp.27-39
• /
• 2019

Objective: The purpose of this study was to examine the effect of the experiences of neglect on adolescent smart phone dependency, exploring the pathways through self-resilience and alienation. Methods: This study utilized the 7th wave data from the Korean Child Youth Panel Survey(KCYPS), and the sample included 1,805 participants with no missing data. The data was analyzed using SPSS 23.0 and AMOS 23.0 programs. Results: First, the experiences of neglect directly affected adolescent smart phone dependency. Second, the experiences of neglect indirectly affect smart phone dependency partially mediated by self resilience and alienation. Conclusions: The ways to prevent adolescent smart phone dependency were discussed.

• KIPS Transactions on Software and Data Engineering
• /
• v.8 no.2
• /
• pp.67-78
• /
• 2019

Accurate electric load forecasting is very important in the efficient operation of the smart grid. Recently, due to the development of IT technology, many works for constructing accurate forecasting models have been developed based on big data processing using artificial intelligence techniques. These forecasting models usually utilize external factors such as temperature, humidity and historical electric load as independent variables. However, due to diverse internal and external factors, historical electrical load contains many missing data, which makes it very difficult to construct an accurate forecasting model. To solve this problem, in this paper, we propose a random forest-based missing data recovery scheme and construct an electric load forecasting model based on multilayer perceptron using the estimated values of missing data and external factors. We demonstrate the performance of our proposed scheme via various experiments.

• Journal of Digital Convergence
• /
• v.17 no.4
• /
• pp.203-210
• /
• 2019

This study analyzed the size and influence factors of annual average health expenditure according to job type. Using data from the Korea Health Panel (2012), the final analysis was conducted on adults aged 20 years or older, excluding the missing data. Data analysis was done by logistic regression analysis to analyze the factors affecting medical expenditure. As a result of the study, Model 1 showed higher expenditure on medical expenses by skilled workers in agriculture and forestry fishery than those in simple labor. Model 2 was analyzed as having a positive effect on the increase of medical expenditure by the simple worker in the sales of the occupation, statistically significant by sex, marriage, income level and chronic disease. Therefore, it would be necessary to establish social security and health care & welfare policies, in order to grasp the disease with a high frequency rate according to occupation status and activate the physical examination and preventive actions.

• The Journal of the Korea Contents Association
• /
• v.21 no.2
• /
• pp.343-350
• /
• 2021

This study aims to investigate the relationship between depression, self-esteem and parental attachment·peer attachment. The study also examines the mediating effect of parental attachment·peer attachment between depression and self-esteem. For these purposes, 315 school dropout adolescent, excluding missing values, were finally analyzed from the 5th School Dropout Adolescent Panel Study(SDAPS). Correlation analysis, mediation analysis performed using SPSS(21.0 version). The findings of the study were as follows. First, it was identified that parental attachment significantly mediated the relationship between depression and self-esteem. Second, it was identified that peer attachment significantly mediated the relationship between depression and self-esteem. Based on the study results, this research suggested the practice and policy implications to increase parental attachment·peer attachment, especially to the school dropout adolescent as well as to increase their self-esteem.