• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.179-185
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• 2008

The purpose of this paper is to propose a systematic method on the weld pitch design of a vehicle sub-frame considering the fatigue life of spot welding points. The input data, which perform the fatigue analysis on the spot welding nuggets, are obtained by both the dynamic analysis of the multi-body vehicle model passing through the virtual proving ground of a typical Belgian road and the quasi-static analysis with the finite element model of the vehicle sub-frame. By utilizing the life cycle data obtained from the fatigue analysis, the welding points to perform the pitch change are determined. The sensitivity analysis on the fatigue life of the welding points is carried out by using the three-level orthogonal array design, and through the results of the sensitivity analysis, the best combination on the welding pitch is determined. This study shows that as compared with the baseline design, the sub-frame redesigned by the proposed technique improves the fatigue life about 7 percent while reducing the number of welding points about 19 percent.

• International Journal of Advanced Culture Technology
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• v.11 no.2
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• pp.256-266
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• 2023

The purpose of this study is to investigate the relationship between stress and school life adaptation according to the degree of participation in physical education class and perception of middle school students. In order to achieve this research objective, the subjects of this study were sampled using cluster random sampling from male and female students attending middle schools in Gwangju Metropolitan City and Jeollanam-do in 2020. 150 males and 150 females, a total of 300 people were sampled. The statistical analysis used for data analysis was frequency analysis, exploratory factor analysis, reliability analysis, and multiple regression analysis using SPSS Windows 21.0 Version. The conclusions obtained in this study through data analysis by such methods and procedures are as follows. First, it was found that middle school students' participation in physical education classes and perceptions had a partial effect on stress. Second, it was found that the degree of participation and awareness of middle school students' physical education class had a partial effect on their adaptation to school life. Third, middle school students' stress was found to have a partial effect on school life adaptation.

• Journal of the Korean Operations Research and Management Science Society
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• v.28 no.4
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• pp.39-60
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• 2003

In this study, we evaluate financial performance of 21 domestic life insurers using SAW (simple additive weighting), ELECTREII, cluster analysis respectively, and suggest a hybrid approach of combining cluster analysis and ELECTREII to reclassify the life insurers into more meaningful groups according to their respective financial features. We also perform the sensitivity analysis employing ANOVA and Tukey's test to examine the robustness of ELECTREII, which would be influenced by decision maker's subjective preference parameters. Consequently, it is shown that ELECTREII turns out to be a flexible method providing decision makers with useful ranking Information especially under fuzzy decision making situation with incomparable alternatives, and hence it can serve as a complementary method to overcome the weakness of classical cluster analysis.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.2
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• pp.134-142
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• 2002

LCC (Life-Cycle Cost) analysis is a practical method and a guideline for evalua-ting the economic performance of building service systems. By using the LCC analysis, the most cost-effective design decision can be made, which has the lowest LCC during the project study period among the various design alternatives. The present case shows an example of appro-priate use of the LCC analysis, by demonstrating the procedures of decision making among at-tarnative building HVAC systems at community center and congress hall of a local government.

• Journal of Family Resource Management and Policy Review
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• v.16 no.1
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• pp.85-101
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• 2012

This study aims to identify the propensity to consume and housing characteristics according to life cycle as the main independent variable. It also tries to understand the consumption power and housing style of each cycle and analyze whether there are differences between each life cycle, ultimately aiming to match the propensity to consume and housing style with each cycle. For empirical analysis, on and off-line surveys of 488 people were collected and analyzed by cross analysis, factor analysis and analysis of variance. The prime research findings are as follows: First of all, factor analysis on propensity to consume showed four main sub-factors as rational consumption, conspicuous consumption, trend consumption, and status consumption. Secondly, current and preferred housing styles ranked from modern, natural, casual, classic and romantic, which proved that people are currently housed in preferred housing styles. Thirdly, in case of housing-related characteristics of life cycles, the size of the house increased as the levels progressed, and then decreased at level 6 when the children grew into adulthood. The majority of the population was paying a monthly rent, a few were leasing, and a very few owned their housing. 58% were living in apartments, but in levels 1-2, more were living in row houses and high-rise residential buildings, while in level 6 it was detached houses. Fourthly, the propensity to consume according to life cycle tended to shift from conspicuous and trend-based consumption to rational consumption as the cycles progressed. Fifthly, the preferred housing styles were modern and natural styles, regardless of life cycle. These study results can be applied to product development and marketing activities based on their accurate analysis of customers' needs, which can thus bring further customer satisfaction.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.10
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• pp.1528-1534
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• 2001

In order to improve Leak-Be(ore-Break methodology, more precisely the crack growth evaluation, a round robin analysis was proposed by the CEA Saclay. The aim of this analysis was to evaluate the crack initiation life, penetration life and shape of through wall crack under cyclic bending loads. The proposed round robin analysis is composed of three main topic; fatigue crack initiation, crack propagation and crack penetration. This paper deals with the first topic, crack initiation in a notched pipe under four point bending. Both elastic-plastic finite element analysis and Neuber's rule were used to estimate the crack initiation life and the finite element models were verified by mesh-refinement, stress distribution and global deflection. In elastic-plastic finite element analysis, crack initiation life was determined by strain amplitude at the notch tip and strain-life curve of the material. In the analytical method, Neuber's rule with the consideration of load history and mean stress effect, was used for the life estimation. The effect of notch tip radius, strain range, cyclic hardening rule were examined in this study. When these results were compared with the experimental ones, the global deformation was a good agreement but the crack initiation cycle was higher than the experimental result.

• Journal of the Korean Home Economics Association
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• v.42 no.9
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• pp.111-134
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• 2004

The purpose of this dissertation is firstly to examine the level of pro-environmental behavior of urban employed wives depending on their life style type and secondly to identify effective ways to promote their pro-environmental behavior. A structured questionnaire interview was conducted with 700 urban employed wives who lived in the Seoul Metropolitan area, and 566 of the responses were valid for analysis. For statistical analysis, this research reviewed the frequencies, percentage, mean, standard deviation(SD), Pearson's correlations, Cronbach's u, factor analysis, cluster analysis, ANOVA, $\chi$$^2$-test, Duncan's Multiple Range Test, and multiple regression using SPSS/PC WIN. The findings of analysis of the study are as follows: 1. Among life style types of employed wives, the order of ecological value was orientation type (37.3%), followed by economical value orientation type (25.8%), uninterested type (18.7%), and convenience-centric value orientation type (18.2%).Pro-environmental behavior scored relatively highly at 3.45 in average. 2. In the analysis of the relationship between life style and background variations, every variation except environmental knowledge was meaningful. 3. In the relationship between pro-environment behavior and background variations, every variation was meaningful except housing types, having helper or not, and environmental knowledge. 4. The recognition level of environmental pollution was important among the variations affecting pro-environmental behavior. 5. There was a difference in pro-environmental behaviors by the following life style types: ecological value orientation, economical value orientation, convenience centric orientation and uninterested. 6. For the relative contribution comparison of background variations (socio-economic variation and environmental variation) and life style variations to the pro-environmental behavior of urban empolyed wives, this research additionally applied each independent variable group. As a result, the explanation level drastically increased in the third step that analyzed the relationship with life style.

• Tribology and Lubricants
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• v.31 no.6
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• pp.272-280
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• 2015

Recently, Luu suggested fatigue life equation that uses every term of the Crossland equation with stress gradient effect. Luu’s model, however, has a limit of being unable to coverage small radii that are less than a specified length. Furthermore, rolling model has a very small contact area compared to the rolling element size, and fatigue failure occurs on the small radius such as surface asperity by cyclic loading. Therefore, it is necessary to modify fatigue life equation in order to enable fatigue analysis for a small radius. In this paper, the fatigue life considering a stress gradient effect in rolling contact was obtained using Luu’s modified equation. Fatigue analysis was performed to study the effect of stress gradient on the fatigue life using newly adopted equation and to compare the results with pervious models. In order to do this, a series of simulation such as surface stress analysis, subsurface stress analysis, and fatigue analysis are conducted for two rolling balls of same size that contact each other. Through such a series of processes, the fatigue life can be calculated and equation that is proposed in this paper evaluates the fatigue life in case the contact area is small.

• Molecules and Cells
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• v.42 no.3
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• pp.237-244
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• 2019

Understanding the mechanisms of cancer drug resistance is a critical challenge in cancer therapy. For many cancer drugs, various resistance mechanisms have been identified such as target alteration, alternative signaling pathways, epithelial-mesenchymal transition, and epigenetic modulation. Resistance may arise via multiple mechanisms even for a single drug, making it necessary to investigate multiple independent models for comprehensive understanding and therapeutic application. In particular, we hypothesize that different resistance processes result in distinct gene expression changes. Here, we present a web-based database, CDRgator (Cancer Drug Resistance navigator) for comparative analysis of gene expression signatures of cancer drug resistance. Resistance signatures were extracted from two different types of datasets. First, resistance signatures were extracted from transcriptomic profiles of cancer cells or patient samples and their resistance-induced counterparts for >30 cancer drugs. Second, drug resistance group signatures were also extracted from two large-scale drug sensitivity datasets representing ~1,000 cancer cell lines. All the datasets are available for download, and are conveniently accessible based on drug class and cancer type, along with analytic features such as clustering analysis, multidimensional scaling, and pathway analysis. CDRgator allows meta-analysis of independent resistance models for more comprehensive understanding of drug-resistance mechanisms that is difficult to accomplish with individual datasets alone (database URL: http://cdrgator.ewha.ac.kr).

• Journal of Industrial Convergence
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• v.21 no.4
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• pp.111-121
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• 2023

The purpose of this study is to provide basic data for improving life satisfaction by verifying the mediating effect of self-esteem in the relationship between physical health awareness, depression, self-esteem, and life satisfaction of middle-aged. Analysis data were collected through online and offline questionnaires for 320 middle-aged people for 10 days from August 15, 2021, and the SPSS WIN 23.0 program was used. As for the analysis method, frequency analysis, descriptive statistical analysis, and correlation analysis Baron & Kenny (1986) were performed in three stages of regression analysis. The research results showed First, that physical health awareness and depression of middle-aged people had a statistically significant effect on life satisfaction. Second, in the relationship between physical health awareness and life satisfaction, self-esteem showed a partial mediating effect. Third, in the relationship between depression and life satisfaction, self-esteem showed a partial mediating effect. In other words, in order to improve life satisfaction for middle-aged people, the basis for improving physical health awareness and self-esteem and reducing depression was prepared, and implications and suggestions for practice were presented.