• 대한기계학회논문집
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• 제18권12호
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• pp.3149-3158
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• 1994

In this paper, using the formulation of dynamic equivalent load considering the effects of moment load and the equation to estimate the cage rotational speed, the new life equation of deep groove ball bearing under radial and moment loads was proposed. Fatigue life test apparatus with the measuring equipment of shaft and cage speed was designed and developed to be capable of subjecting combined radial and moment load. Fatigue life tests were executed by sudden death test method and the reliability of fatigue lives was evaluated by Weibull distribution analysis. From the results of fatigue tests and analysis, the relationships between film parameters and life adjustment factors were acquired. And it was turned out that so as to estimate the effect of moment load on fatigue life, the life adjustment factor as well as the dynamic equivalent load must be taken into account.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.690-693
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• 2005

In this paper, probabilistic distribution of fatigue life of chassis component is determined statistically by applying the design of experiments and the Pearson system. To construct $p-\varepsilon-N$ curve, the case that fatigue data are random variables is attempted. Probabilistic density function(p.d.f) for fatigue life is obtained by design of experiment and using this p.d.f fatigue reliability about any aimed fatigue life can be calculated. Lower control arm and rear torsion bar of chassis component are selected as examples for analysis. Component load histories, which are obtained by multi-body dynamic simulation for Belsian load history, are used. Finite element analysis are performed using commercial software MSC Nastran and fatigue analysis are performed using FE Fatigue. When strain-life curve itself is random variable, probability density function of fatigue life has very little difference from log-normal distribution. And the case of fatigue data are random variables, probability density functions are approximated to Beta distribution. Each p.d.f is verified by Monte-Carlo simulation.

• International Journal of Reliability and Applications
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• 제15권2호
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• pp.125-150
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• 2014

Accelerated life tests (ALTs) are extensively used to determine the reliability of a product in a short period of time. Test units are subject to elevated stresses which yield quick failures. ALT can be carried out using constant-stress, step-stress, progressive-stress, cyclic-stress or random-stress loading and their various combinations. An ALT with linearly increasing stress is ramp-stress test. Much of the previous work on planning ALTs has focused on constant-stress, step-stress, ramp-stress schemes and their various combinations where the stress is generally increased. This paper presents an optimal design of ramp soak-stress ALT model which is based on the principle of Thermal cycling. Thermal cycling involves applying high and low temperatures repeatedly over time. The optimal plan consists in finding out relevant experimental variables, namely, stress rates and stress rate change points, by minimizing variance of reliability function with pre-specified mission time under normal operating conditions. The Burr type XII life distribution and time-censored data have been used for the purpose. Burr type XII life distribution has been found appropriate for accelerated life testing experiments. The method developed has been explained using a numerical example and sensitivity analysis carried out.

• 한국정밀공학회지
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• 제24권2호
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• pp.110-117
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• 2007

In this paper, probabilistic distribution of chassis component fatigue life is determined statistically by applying the design of experiments and the Pearson system. To construct p - ${\varepsilon}$ - N curve, the case that fatigue data are random variables is attempted. Probabilistic density function (p.d.f) for fatigue life is obtained by the design of experiment and using this p.d.f fatigue reliability, any aimed fatigue life can be calculated. Lower control arm and rear torsion bar of chassis components are selected as examples for analysis. Component load histories which are obtained by multi-body dynamic simulation for Belsian load history are used. Finite element analysis is performed by using commercial software MSC Nastran and fatigue analysis is performed by using FE Fatigue. When strain-life curve itself is random variable, the probability density function of fatigue life has very little difference from log-normal distribution. And the cases of fatigue data are random variables, probability density functions are approximated to Beta distribution. Each p.d.f is verified by Monte-Carlo simulation.

• 대한기계학회논문집
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• 제15권6호
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• pp.1908-1918
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• 1991

본 연구에서는 피로 잔류강도저하(fatigue residual strength degradation) 개념을 이용하여 복합재료의 잔류강도와 피로수명을 예측하고 실험을 통하여 비교 평 가하였으며, 설계시 고려되어야 할 인자를 파악하여 파손방지를 위한 유한 수명설계 및 손상허용설계의 기본자료를 집적함으로서 새로운 소재인 탄소섬유 강화 복합재료의 신뢰성 향상을 위한 개발과 고강도 경량화를 위한 이용설계에 활용할 수 있도록 하는 데 그 목적이 있다.

• The Plant Pathology Journal
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• 제39권6호
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• pp.575-583
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• 2023

Fusarium root rot is an increasingly severe problem in soybean cultivation. Although several Fusarium species have been reported to infect soybean roots in Heilongjiang province, their frequency and aggressiveness have not been systematically quantified in the region. This study aimed to investigate the diversity and distribution of Fusarium species that cause soybean root rot in Heilongjiang province over two years. A total of 485 isolates belonging to nine Fusarium species were identified, with F. oxysporum and F. solani being the most prevalent. Pot experiments were conducted to examine the relative aggressiveness of different Fusarium species on soybean roots, revealing that F. oxysporum and F. solani were the most aggressive pathogens, causing the most severe root rot symptoms. The study also assessed the susceptibility of different soybean cultivars to Fusarium root rot caused by F. oxysporum and F. solani. The results indicated that the soybean cultivar DN51 exhibited the most resistance to both pathogens, indicating that it may possess genetic traits that make it less susceptible to Fusarium root rot. These findings provide valuable insights into the diversity and distribution of Fusarium species that cause soybean root rot and could facilitate the development of effective management strategies for this disease.

• 한국디지털건축인테리어학회논문집
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• 제7권2호
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• pp.73-78
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• 2007

Proper methods for facilities distribution are suggested by the examination of researches on facilities distribution, the analysis of the scope that facilities are used, and the consideration of facilities demand, and proper distribution and placement of facilities suitable for each stage is suggested. The theoretical examination for proper distribution and the analysis of the use scope is made. As a result. the area covers four dongs(administrative unit) within 1km. The $80{\sim}90%$ of residents who use the existing facilities are the ones living within 1km and so the zone of life in everyday life depending on walking as a means of movement is found to be expanded by the developments in transportation means and road construction. Therefore I suggested that lifetime sports facilities be established within the use scope whose radius and area are 1km and 4km2, respectively, regarding the sports facilities as a community center which can playa role of an institution of community center.

• Journal of applied mathematics & informatics
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• 제41권6호
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• pp.1275-1301
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• 2023

This paper introduced the Weibull Marshall-Olkin Power Lomax (WMOPL) distribution. The statistical aspects of the proposed model are presented, such as the quantiles function, moments, mean residual life and mean deviations, variance, skewness, kurtosis, and reliability measures like the residual life function, and stress-strength reliability. The parameters of the new model are estimated using six different methods, and simulation research is illustrated to compare the six estimation methods. In the end, two real data sets show that the Weibull Marshall-Olkin Power Lomax distribution is flexible and suitable for modeling data.

• 산경연구논집
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• 제10권12호
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• pp.25-34
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• 2019

Purpose - In this study, we would like to analyze how the general characteristics of retired senior citizens affect directly the satisfaction of retirees' lives. As the life cycle continues to grow longer, post-retirement environment is recognized as important, and this study is conducted to analysis the factors that concerns which parts influence future retirement life. Research design, data, and methodology - First, Pearson's correlation analysis was conducted to analyze the correlation between the satisfaction of retirement life and the characteristics of the elderly. Secondly, a one-way analysis of variance was conducted to find out the difference in the satisfaction level of post-retirement life depending on the characteristics of the elderly. Results - First, the demographic factors for the satisfaction of retirement life have shown a definite difference. Second, the family factors for the satisfaction of retirement life have shown a clear difference. Third, financial factors for the satisfaction of retirement life have shown a clear difference. Conclusions - Early retirement, especially in major jobs, is the basis for incomplete retirement preparation, which is a factor in unstable later life. If a prospective retiree can retire in a predictable retirement age, it would be sufficient to prepare for retirement in various areas, or to prepare for further directions.

• 산경연구논집
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• 제10권10호
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• pp.15-21
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• 2019

Purpose - This study is intended to explore influential factors on the life satisfaction of physically challenged laborers preparing for support plans for their future. This is to enjoy a better life and have social opportunities and to review institutional support or plans for implementation to be applied for physically challenged people. Research design, data, and methodology - 4,161 disabled people participated in the Panel Survey of Employment of the Disabled. Among 2,124 physically challenged people, 957 wage workers (45%) were primarily extracted in this study, and a total of 581 (27%) with sufficient responses on the questionnaires were finally selected. Results - First, physical preparation for later life had a positive influence on retired life satisfaction among retirement satisfaction. People showed higher retired life satisfaction. Secondly, physical preparation for later life had a positive influence on satisfaction over relationship after retirement among retirement satisfaction. Conclusions - In this study, it was found that job satisfaction was the variable with the highest influential power on life satisfaction. Therefore, it seems to be necessary to proceed a research as to which factors influence life satisfaction in the medium of job satisfaction and also about plans to improve job satisfaction on experts or the disabled.