• Proceedings of the KSME Conference
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• 2003.04a
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• pp.445-450
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• 2003

This study was performed 10 develop the accelerated life test method using Weibull-IPL(Inverse Power Law) model for mechanical components. Weibull-IPL model is concerned with determining the assurance life with confidence level and the accelerated life test time From the relation of weibull distribution factors and confidence limit, the testing times on the no number of failure acceptance criteria arc determined. The mechanical components generally represent wear and fatigue characteristics as a failure mode. IPL based on the cumulative damage theory is applied effectively the mechanical components to reduce the testing time and to achieve the accelerating test conditions. As the actual application example, accelerated life test method of agricultural tractor transmission was described. Life distribution of agricultural tractor transmission was supposed to follow Weibull distribution and life test time was calculated under the conditions of average life (MTBF) 3,000 hours and 90% confidence level for one test sample. According to IPL, because test time call be shorten in case increase test load test time could be reduced by 482 hours when we put the load 1.1 times of rated load than 0.73 times of rated load that is equivalent load calculated by load spectrum of the agricultural tractor. This time, acceleration coefficient was 11.7.

• Journal of Korean Society of Rural Planning
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• v.21 no.4
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• pp.139-155
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• 2015

This study was conducted to effectively develop rural tourism in Korea. For the purpose, tourism that can develop with local industries and cultures together was designated as life-type tourism and development models of such tourism were reviewed based on an understanding that province-oriented tourism is necessary. An analysis of three actual cases of Japan led to following results. First, life-type tourist destinations can be developed in connection with making local areas based on their special themes, can be developed in relation to their life cultures based on their peculiar life cultures and can be developed in creative forms using characteristic environment and organizational culture of those areas. In pursuing life-type tourist attractions, it will be possible to make practical development using it with those three basic models. Second, it is important to form a flow covering the entire regions based on their own special themes, to build cyclical structure of regions and tourism and tourism and industries and to create overall conditions that can help local residents get benefits and join together, in order to develop such life-type tourist destinations. Development of life-type resort tourist destinations needs roles of practical organizations that can effectively manage them, but such organizations should be dynamic and should be distant from management of money as much as possible.

• Korean Journal of Adult Nursing
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• v.20 no.2
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• pp.187-199
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• 2008

Purpose: This study is to develop a hypothetical structural model of the quality of life of single aged women and to explain the compatibilities between the models and actual data. Methods: Ten theoretical variables were used to evaluate of the quality of life of single aged women. 300 of single aged women were selected as the subjects. A hypothetical prediction model of quality of life was tested by the covariance structure analysis with PC-LISREL 8.12. Results: Economy, religion activity, leisure activity, social support, self-esteem, depression and health prompting behavior were the significant variables which affected to the quality of life directly in the single aged women. But social support, self-esteem affected to them indirectly. Knowing perceived health status directly but it affected indirectly to the quality of life in single aged women. Conclusion: In this study, it was discovered that self-esteem was the most important factor to affect to the quality of life in single aged women and the next was the depression and health promoting behavior. As a result, it was discovered that age, economic status, self-esteem and depression were the significant factors to affect to the quality of life in single aged women.

• 연구논문집
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• s.32
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• pp.35-43
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• 2002

This study was performed to develop accelerated life test method of machanical parts using cumulative damage theory that used to model the fatigue of parts that receive variable load. The cumulative damage theory was introduced, and the estimation of life and calculation of accelerated life test time was illustrated. As the actual application example, accelerated life test method of agricultural tractor transmission was described. Life distribution of agricultural tractor transmission was supposed to follow Weibull distribution and life test time was calculated under the conditions of average life (MTBF) 3,000 hours and 90% reliability for one test sample. According to the cumulative damage theory, because test time can shorten in case increase test load, test time could be reduced by 482 hours when we put the load 1.1 times of rated load than 0.73 times of rated load that is equivalent load calculated by load spectrum of the agricultural tractor. This time, acceleration coefficient was 11.7. This accelerated test method was used to develop accelerated test method of gear reducer, hydraulic hose and bearing as well as agricultural tractor transmission and it is considered to be applied comprehensively to machanical parts the fatigue of which is happened by load or pressure etc.

• IE interfaces
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• v.4 no.2
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• pp.35-42
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• 1991

Many authors derived MTTF/MTBF for an operating system by analyzing its actual life time data. However, it is difficult to derive MTTF/MTBF when few breakdowns accur throughout a year. In this paper, we address a new approach to solve that problem under a preventive maintenance policy, in which few breakdowns occur, and also introduce a case study using the results obtained.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.764-771
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• 2012

In order to develop constructed wetlands for treating hydroponic wastewater in greenhouse, actual constructed wetlands were used the obtained optimum condition in previous study, and the removal rate of pollutant in the water according to 4 kinds connection method of piping such as system A (UP-UP stream), system B (UP-DOWN system), system C (DOWN-UP stream) and system D (DOWN-DOWN stream) were investigated. Removal rate of biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), total nitrogen (T-N) and total phosphorus (T-P) by system A (UP-UP stream) connection method in actual constructed wetlands were slightly higher than other systems. At the system A, the removal rate of BOD, COD, SS, T-N and T-P were 88, 77, 94, 54 and 94%, respectively. Under different hydroponic wastewater loading, the removal rates of pollutants were higher in the order of $75L\;m^{-2}day^{-1}{\fallingdotseq}150L\;m^{-2}day^{-1}$ $$\geq_-$$ $300L\;m^{-2}day^{-1}$. Therefore, optimum connection method was system A for treating hydroponic wastewater in greenhouse.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.12
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• pp.1153-1157
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• 2013

A steam turbine blade is one of the core parts in a power plant. It transforms steam energy into mechanical energy. It is installed on the rim of a rotor disk. Many failure cases have been reported at the final stage blades of a low-pressure (LP) turbine that is cyclically loaded by centrifugal force because of the repeated startups of the turbine. Therefore, to ensure the safety of an LP steam turbine blade, it is necessary to investigate the fatigue strength and life. In this study, the low cycle fatigue life of an LP steam turbine blade is evaluated based on actual damage analysis. To determine the crack initiation life of the final stage of a steam turbine, Neuber's rule is applied to elastic stresses by the finite element method to calculate the true strain amplitude. It is observed that the expected life and actual number of starts/stops of the blade were well matched.

• Korean Journal of Agricultural Science
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• v.47 no.1
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• pp.43-58
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• 2020

Mulching plastic is used for the purpose of maintaining soil temperature, moisture, and weed and pest prevention in agriculture. Any remaining plastic after use may contaminate the soil and damage crop growth. To solve this problem, mulching plastic wrappers have been studied and developed, but the actual use rate is quite low due to their poor performance and frequent tearing of the plastic on the field. In this study, we developed a tractor attachable mulching plastic wrapper to minimize the tearing of the mulched plastic. The developed mulching plastic wrapper consists of hydraulic motors and pumps, valves, a microcontroller, and sensors. The collecting speed of the plastic mulch was calculated considering the tractor's travel speed and the radius of the collecting drum. A proportional controller was designed to control the rotating speed of the hydraulic motor as the plastic was wound around the collection drum and the radius increased. The performance of an indoor experiment was quite promising because the difference between the collecting speed predicted by the calculation and the actual collecting speed was 2.71 rpm. Based on a field verification test, the speed difference was max. 14.28 rpm; thus, the, proportional integral derivative (PID) controller needs to be considered to control the drum speed precisely. Another issue was found when the soil covered at the edge of the plastic was hardened or the road surface was uneven, the speed control was unstable, and the plastic was torn. In future research, vibrational plows will be equipped to break-up the harden soil for collecting the plastic smoothly.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.34 no.4
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• pp.5-27
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• 2023

Gagné proposed nine instructional events, gain attention of the students, inform students of the objectives, stimulate recall of prior learning, present the content, provide learning guidance, elicit performance(practice), provide feedback, assess performance, enhance retention and transfer for effective teaching & learning practice. Gagné's theory is widely applied in various subjects because it increases student participation and allows classes to be developed systematically. The purpose of this study is to develop a lesson plans for the 'library and information life' subjects in middle school using Gagné's nine instructional events theory, conduct actual instructions, and verify its effectiveness. The research procedure was conducted as follows. Development of lesson plan that using Gagné's theory to Section III (Information Analysis and Interpretation) of 'Library and Information Life' in middle school. Actual instruction were conducted and student survey, peer teacher assessment, and instructor self-assessment were conducted. Based on the evaluation results, a elements to revise and improve the lesson plan was presented.

• Proceedings of the Korean Reliability Society Conference
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• 2006.05a
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• pp.116-125
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• 2006

Piston assemblies, which are key components of hydraulic high pressure pumps & motors, are major failure products operating at high pressure and high speed, and the main failure mode is wearout of the shoe surface. To predict the actual life of piston assemblies. we require to find out the most sensitive parameters and establish related empirical formula. In this study, we analyzed the life of piston and shoe assemblies in accordance with variation of speed, pressure, and temperature to reduce the life test time, then analyzed the result of combined accelerated life test which is applied by high speed, speed pressure, and high temperature simultaneously, and finally developed combined accelerated life test model.