• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.445-450
• /
• 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.

• 농촌계획
• /
• 제21권4호
• /
• pp.139-155
• /
• 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.

• 성인간호학회지
• /
• 제20권2호
• /
• pp.187-199
• /
• 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
• /
• 통권32호
• /
• pp.35-43
• /
• 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.

• 산업공학
• /
• 제4권2호
• /
• pp.35-42
• /
• 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.

• 한국토양비료학회지
• /
• 제45권5호
• /
• pp.764-771
• /
• 2012

질소 및 인 함유 폐양액 처리를 위한 최적 인공습지 시스템을 선정하기 위해 처리조의 연결방식을 달리하여 최적 system을 선정하였고, 선정된 최적조건하에서 폐양액 부하량에 대한 적응성을 평가하였다. 현장 폐양액처리장에서 시스템별 정화효율을 평가한 결과 system A의 BOD, COD, SS, T-N 및 T-P의 처리효율은 각각 88, 77, 94, 54 및 94%로서 다른 시스템에 비해 가장 높은 정화효율을 보였다. 현장 폐양액처리장에서 폐양액 부하량별 수처리 효율을 조사한 결과 system A의 BOD, COD, SS, T-N 및 T-P의 처리효율은 폐양액 부하량에 따라 별 차이 없이 각각 87-89, 76-79, 93-94, 52-55 및 91-94%로 전반적으로 높고 안정적으로 처리되었다. 하지만 T-N의 처리효율은 55% 정도 수준으로 폐수배출기준을 안정적으로 만족하기 위해서는 질소처리효율을 좀 더 향상시킬 필요가 있을 것으로 판단된다.

• 대한기계학회논문집B
• /
• 제37권12호
• /
• pp.1153-1157
• /
• 2013

증기터빈의 터빈 블레이드는 발전소 핵심설비 중 하나로, 로터의 디스크에 결합되어 회전함으로 써 증기 에너지를 기계적 에너지로 변환시켜주는 역할을 하고 있다. 최근 터빈의 잦은 기동정지로 인해 블레이드 회전에 따른 원심하중이 반복적 작용하고 이에 따른 저압 증기터빈 최종단 블레이드의 손상이 자주 보고되고 있다. 본 논문에서는 터빈 블레이드에 발생되는 손상을 분석하여 블레이드에 발생되는 저주기 피로수명을 평가하였다. 증기터빈 최종단 블레이드의 균열발생 수명을 결정하기 위해 유한요소법으로 계산한 탄성응력에 Neuber's rule을 적용하여 진변형율 진폭을 계산하였으며, 예측된 수명과 블레이드 실제 기동정지횟수가 잘 일치됨을 보였다.

• 농업과학연구
• /
• 제47권1호
• /
• pp.43-58
• /
• 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.

• 한국비블리아학회지
• /
• 제34권4호
• /
• pp.5-27
• /
• 2023

가네는 효과적인 교수·학습을 위한 9가지의 교수사태-주의집중, 학습목표 제시, 선수학습능력 재생, 학습자료 제시, 학습지침 제공, 학생수행 요구, 피드백 제공, 성취행동 평가, 파지와 전이-를 제안하였다. 가네의 이론은 학생들의 참여를 높이고, 체계적으로 수업을 전개할 수 있기 때문에 여러 교과에서 널리 적용되고 있다. 본 연구의 목적은 가네의 교수사태 이론을 적용하여 중학교 '도서관과 정보생활' 교과의 학습지도안을 개발하고 그 효과를 검증하는데 목적이 있다. 연구절차는 다음과 같다. 중학교 '도서관과 정보생활'의 정보분석과 이해)을 가네의 교수사태이론을 적용하여 학습지도안을 개발하고 실제 수업을 진행한 후, 학생 평가, 동료교사 평가, 교수자 자기 평가를 실시하였다. 평가 결과를 바탕으로 학습지도안의 수정 및 개선 방안을 제시하였다.

• 한국신뢰성학회:학술대회논문집
• /
• 한국신뢰성학회 2006년도 학술발표대회 논문집
• /
• pp.116-125
• /
• 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.