• Journal of Mechanical Science and Technology
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• v.18 no.11
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• pp.1989-1995
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• 2004

Finite element analysis(FEA) is the most popular numerical method to simulate plasticity-induced fatigue crack closure and can predict fatigue crack closure behavior. Finite element analysis under plane stress state using 4-node isoparametric elements is performed to investigate the detailed closure behavior of fatigue cracks and the numerical results are compared with experimental results. The mesh of constant size elements on the crack surface can not correctly predict the opening level for fatigue crack as shown in the previous works. The crack opening behavior for the size mesh with a linear change shows almost flat stress level after a crack tip has passed by the monotonic plastic zone. The prediction of crack opening level presents a good agreement with published experimental data regardless of stress ratios, which are using the mesh of the elements that are in proportion to the reversed plastic zone size considering the opening stress intensity factors. Numerical interpolation results of finite element analysis can precisely predict the crack opening level. This method shows a good agreement with the experimental data regardless of the stress ratios and kinds of materials.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.3
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• pp.151-162
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• 2000

This study is concerned with computerized multi-level substructuring methods and stress analysis of coil springs. The purpose of substructuring methods is to reduce computing time and capacity of computer memory by multiple level reduction of the degrees of freedom in large size problems that are modeled by three dimensional continuum finite elements. In this paper, the spring super element developed is investigated with tension, torsion, and bending of a cylindrical bar in order to verify its accuracy and efficiency for the multi-level substructuring method. And then the algorithm is applied to finite element analysis of coil springs. The result demonstrates the validity of the multi-level substructuring method and the efficiency in computing time and memory by providing good computational results in coil spring analysis.

• Journal of Navigation and Port Research
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• v.30 no.8 s.114
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• pp.669-674
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• 2006

The purpose of this study is to examine the effects of the factors on the usage level of e-business in the shipping companies. In order to do empirical analysis, firstly, this study carried out reliability analysis and factor analysis. Secondly, this study examined the effects of the factors on the usage level of e-business in the shipping companies by multiple regression analysis. In conclusion, the analysis result revealed that 5 factors effect on the service business usage's level and 4 factors effect on the real transaction usage's level of e-business.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.319-326
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• 2004

Uncertainty is inevitably involved in rock slope engineering since the rock masses are formed by natural process and subsequently the geotechnical characteristics of rock masses cannot be exactly obtained. Therefore the reliability analysis method has been suggested to deal properly with uncertainty. The reliability analysis method can be divided into level I, II and III on the basis of the approach for consideration of random variable and probability density function of reliability function. The level II approach, which is focused in this study, assumes the probability density function of random variables as normal distribution and evaluates the probability of failure with statistical moments such as mean and standard deviation. This method has the advantage that can be used the problem which the Monte Carlo simulation approach cannot be applied since the complete information on the random variables are not available. In this study, the analysis results of level II reliability approach compared with the analysis results of level III approach to verify the appropriateness of the level II approach. In addition, the results are compared with the results of the deterministic analysis.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.1
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• pp.94-106
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• 2024

In this study, we conducted a survival analysis on battalion-level commanders(leaders), focusing on infantry battalion defensive operations using the big data of brigade-level KCTC(Korea Combat Training Center) training results. Unlike previous studies, we utilized the brigade-level KCTC training results data for the first time to conduct a survival analysis, and the research subjects were battalion-level commanders(leaders), which can affect the battle. At this time, the battle results were defined, and through cluster analysis, infantry battalions were divided into excellent, average, and insufficient units, and the difference in the survival rate of the commanders was analyzed through the Kaplan-Meier survival analysis. This provided an opportunity to objectively compare the differences between excellent and insufficient units. Subsequently, factors affecting the survival of commanders were derived using the Cox proportional hazard model, and it was possible to confirm the influencing factors from various angles by also using the survival tree model. Significance and limitations confirmed in the research process were presented as policy suggestions and future research directions.

• Journal of Families and Better Life
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• v.8 no.2
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• pp.101-118
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• 1990

The purpose of this study is to examine the stress level and factors percepted by the married women during family life, and to identify the related variables influencing on stress level. For this purpose, questionnaires were distributed to the 650 married women who have been living in seoul. Among them 463 data were selected. For data analysis, the statistical method such as the factor analysis frequency distribution percentile , t-test, ANOVA, Duncan's Multiple Range Test and Stepwise Regression Analysis were used. the major findings were summarized as follows; 1) The general tendancy of the stress level percepted by the married women during family life was relatively low. 2) The household background variables(age, level of education, income, type of family, number of children, status of employment ) have turned out to be significant on the stress level of married women except family type. 3) All the social-psychological variables(socio-economic status, communication interaction, resources perception, psychological satisfaction) showed significant differences according to the stress level percepted by the married women during family life. 4) The level of work identity was the important factor on the stress level percepted by the married women during family life. 5) In Stepwise Multiple Regression Analysis, the married women's stress level during family life was greatly influenced by variables such as the resource perception and the psychological satisfaction.

• Journal of Korean Society on Water Environment
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• v.26 no.6
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• pp.954-962
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• 2010

The objective of this study was to develop automatic event detection algorithm for groundwater level rise. The groundwater level data and rainfall data in July and August at 37 locations nationwide were analyzed to develop the algorithm for groundwater level rise due to rainfall. In addition, the algorithm for groundwater level rise by ice melting and ground freezing was developed through the analysis of groundwater level data in January. The algorithm for groundwater level rise by rainfall was composed of three parts, including correlation between previous rainfall and groundwater level, simple linear regression analysis between previous rainfall and groundwater level, and diagnosis of groundwater level rise due to new rainfall. About 49% of the analyzed data was successfully simulated for groundwater level rise by rainfall. The algorithm for groundwater level rise due to ice melting and ground freezing included graphic analysis for groundwater level versus time (day), simple linear regression analysis for groundwater level versus time, and diagnosis of groundwater level rise by new ice melting and ground freezing. Around 37% of the analyzed data was successfully simulated for groundwater level rise due to ice melting and ground freezing. The algorithms from this study would help develop strategies for sustainable development and conservation of groundwater resources.

• Journal of Fisheries and Marine Sciences Education
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• v.23 no.1
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• pp.67-74
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• 2011

The study was constructed an analysis of postures of a expert diver's wearing and taking off with skinscuba equipment using ergonomics tools(REBA, RULA, OWAS) for prevention of Musculoskeletal injuries. This survey is consisted of 4 postures in terms of wearing and taking off : Crouching(alone), Standing(alone), Helping of assistance, Using of stanchion. Their rate of injuries is getting higher due to instability postures, exposed dangers and excessive physical actions. So this study provides basic and educational information for prevention of that. The result is as follows : The result of crouching postures of wearing alone was REBA 9(Ac Level 3), RULA 7(Ac Level 4), OWAS AC 2, and crouching postures of taking off alone was REBA 12(Ac Level 4), RULA 7(Ac Level 4), OWAS AC 4. The result of standing postures of wearing alone was REBA 8(Ac Level 3), RULA 7(Ac Level 4), OWAS AC 3, and standing postures of taking off alone was REBA 8(Ac Level 3), RULA 7(Ac Level 4), OWAS AC 3. The result of helping of assistance postures of wearing was REBA 4(Ac Level 2), RULA 3(Ac Level 2), OWAS AC 2, and standing postures of taking off alone was REBA 4(Ac Level 2), RULA 4(Ac Level 2), OWAS AC 1. The result of using of stanchion postures of wearing was REBA 3(Ac Level 1), RULA 3(Ac Level 2), OWAS AC 1, and standing postures of taking off alone was REBA 3(Ac Level 1), RULA 3(Ac Level 2), OWAS AC 1. Especially both postures of wearing and taking off alone showed high results in the analysis of postures using ergonomics tools(REBA, RULA, OWAS).

• Journal of the Korea Society of Computer and Information
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• v.22 no.12
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• pp.163-170
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• 2017

The purpose of this study is to introduce policy and theoretical implications by analyzing affecting factors for the elder's happiness. For this study, we analyzed data using HLM. Data include a world value survey(hereafter, WVS) as personal level analysis data and also OECD's Social Expenditure Database(hereafter, SOCX) and database from the World Bank as national level analysis data. The subjects of personal level analysis were the elder who are over 65-years od age, and they were total 3,297 people, and while the subjects of national level analysis were total 9 OECD countries. For the data analysis, hierarchial linear model(HLM) analysis was done by using HML 7.0 program. As a result of analysis, First, for the elderly's happiness, they should improve self-disposition, members of social groups, and social class. Second, the old-age pension and the survivor's pension had no meaningful effect on the happiness. but it was found that self - disposition, social class, gender, and health status showed meaningful interaction effect according to old - age pension, survivor pension, per capita GDP, income inequality. This suggests that efforts to improve the happiness of the elderly should be made at the individual level and the national level at the same time.

• Research in Community and Public Health Nursing
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• v.29 no.4
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• pp.414-428
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• 2018

Purpose: The purpose of this study is to identify the spatial distribution of hypertension prevalence and to investigate individual and regional-level factors contributing to the prevalence of hypertension in the region. Methods: This study is a cross-sectional research using the 2015 Community Health Survey. Total 64,473 people from 7 metropolitan cities were used for the final analysis. Geoda program was adopted to identify the regional distribution of hypertension prevalence and analyzed by descriptive statistics, one-way ANOVA and correlation analysis using SPSS statistics 23.0 program. Multi-level analysis was performed using SPSS (GLMM). Results: The prevalence of hypertension was related to individual level factors such as age, monthly household income, normal salt intake, walking practice days, and regional level factors including number of doctors per 10,000 population, number of parks, and fast food score. Besides, regional level factors were associated with hypertension prevalencies independently without the effects of individual level factors even though the influences of individual level factors ware larger than those of regional factors. Conclusion: Respectively, both individual and regional level factors should be considered in hypertension intervention programs. Also, a national level research is further required by exploring various environmental factors and those influences relating to the hypertension prevalence.