• Journal of Biosystems Engineering
• /
• 제34권5호
• /
• pp.325-330
• /
• 2009

This study was performed to develop accelerated life test methods for agricultural tractor transmission receiving variable load. To acquire parameters for calculation of accelerated life test, endurance tests were performed under different torque conditions. Test results showed that the shape factor of Weibull distribution was 1.5 and fatigue damage exponent was 5.4. The calculated test time was 5,877 hours under the conditions of average life (MTBF) 3,000 hours and 90% reliability for one test sample. According to the linear cumulative damage rule, test time could be reduced using increased test load. Test time could be reduced by 252 hours when 1.2 times of the rated load compared with 0.67 times of the rated equivalent load calculated by load spectrum of the agricultural tractor. Calculated acceleration coefficient was 23.3.

• Journal of Biosystems Engineering
• /
• 제42권4호
• /
• pp.242-250
• /
• 2017

Purpose: This study was conducted to determine the appropriate operating conditions through a factorial experiment for the secondary separating part of the self-propelled pepper harvester. Methods: An experimental setup that simulates the secondary separating part of the self-propelled pepper harvester was organized. Test samples were classified into three types according to the number of peppers on a stem, and 12 sets were prepared for each type. Among the operating conditions of the secondary separating part, the rotational speed of drum B (four levels), radial clearance between drums and cylindrical teeth (three levels), and speed ratio between the three drums (two levels) were set as the test factors, and tests were repeated three times for different levels of each factor. The appropriate operating conditions were determined by analyzing the separation ratio and damage ratio of the peppers collected through the secondary separating part. Results: The test factors changed the overall separation ratio and overall damage ratio in similar trends. In other words, the conditions that caused high overall separation ratios also exhibited high overall damage ratios. Owing to the high overall damage ratio in the condition with the highest overall separation ratio, the operating conditions should be selected considering both ratios. Conclusions: When the condition with more than 60% of overall separation ratio and less than 15% of overall damage ratio was considered as the appropriate operating condition, 70 rpm of the rotational speed of drum B, 5 mm of the radial clearance between drums and cylindrical teeth, and 7:3:5 for the speed ratio of the three drums A, B, and C should be applied for the secondary separating part used in this study. Supplementary studies will be required in the future to find optimal operating conditions through the actual field test under further divided test factors.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1999년도 춘계학술대회논문집
• /
• pp.119-124
• /
• 1999

Quantitative evaluation of the tribological conditions at the tool-workpiece interface in metal forming is usually accomplished by the ring-compressinon. test This paper describes an experimental investigation into shear friction factor under cold and hot forming conditions according to materials and lubricants using the ring compression test. Six different materials and five different lubricants were applied in the experiments. calibration curves with the friction coefficient were obtained using FEM analysis and verified by the verified by the experimental results. The influence of materials and lubricants level on friction are discussed. In the ring compression test the shear friction factor has a different from steels and aluminum water base graphite lubricants on cold working conditions and hot working conditions.

• 한국기계가공학회지
• /
• 제8권3호
• /
• pp.7-12
• /
• 2009

This study aims to find the friction welding and induction harden conditions, which are obtained by welding conditions, and the friction welding characteristics and induction harden conditions of tubular shaft were investigated with respect to low load test, high load test. Friction welding and induction harden machine have been widely used in manufacturing reflects of metal. The material of solid and tubular shaft selected that is used for parts of automobile steel. Such as steel are easy to be machined because of their proper material. As a result I obtained the data of friction welding conditions makes good and the condition of friction and get the tubular condition. The purpose of this study is to find fatigue test condition and induction harden characteristics design for tubular shaft.

• Physical Therapy Rehabilitation Science
• /
• 제3권2호
• /
• pp.134-141
• /
• 2014

Objective: The purpose of this study was to compare with different distance across three conditions in stroke survivors with the grading of cognitive state. Design: Cross-sectional study. Methods: Twelve stroke patients who agreed to active participation were included. Participants were allotted to normal cognitive (CN) group (n=7) and cognitive impairment (CI) group (n=5) and then walked on a self-paced walkway at three conditions on the Time Up and Go (TUG) test and the 6 minute walk test (6MWT): 1) walking with your comfortable speed, 2) walking while carrying a tray with glasses, 3) walking with a verbal cognitive task. The TUG test was repeated three successful times on each condition. For the 6MWT, participants were tested one time. Results: The CI group walked slower than the CN group at the three conditions on the TUG test. However, there was no significant difference between two groups to each condition. A significant effect of dual tasking was found only in error of verbal cognitive task condition for the TUG test (p<0.05). On the 6MWT, the participants in the CI group walked short distance rather than the CN group (p<0.05). There were significant differences between two groups not only at all conditions but also at error of verbal cognitive task condition as well (p<0.05). Conclusions: To consider the results of different distances such as the TUG test and the 6MWT, we think that exercises in long distance would be more effective to patients with CI. Those would be improved patient's endurance in cognitive problem.

• 대한물리의학회지
• /
• 제12권1호
• /
• pp.43-49
• /
• 2017

PURPOSE: This study investigated the relationship among hip adduction angle, tibial rotation, and ITB length during an Ober test to determine the most appropriate position for performing the test. METHODS: The study included thirty-nine asymptomatic participants (23 males, 16 females). Their hip adduction angles were measured using the Ober test during three tibial rotation conditions (internal tibial rotation, external rotation, and neutral position). ITB length was calculated by measuring the position of the patella to lateral femoral condyle using ultrasonography (patella-condyle distance; PCD). RESULTS: The relationship among hip adduction angle, tibial rotation, and ITB length was analyzed under the three conditions using the Pearson correlation. The hip adduction angle of the internal tibial rotation, the external rotation, and the neutral position were significantly related to ITB length. Moreover, the hip adduction angle measured during the internal tibial rotation had the highest correlation with ITB length among the three conditions (r=.58, p<.001). CONCLUSION: Internal tibial rotation caused by the Ober test led to increased iliotibial band (ITB) tension and a decreased adduction angle. These findings support that tibial rotation influences the flexibility of ITB. Therefore, therapists should consider the position of the internal tibial rotation when taking measurements using an Ober test.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제18권1호
• /
• pp.40-48
• /
• 2018

Purpose: This research is to develop Trailer Durability Test of towing device, in order to cover usage conditions of bike type as well as general type trailer. With the diversification of leisure activities, the population that enjoys various sports and leisure has increased rapidly, and the number of vehicles equipped with camping trailers and bike carriers is also increasing steadily. The purpose of this study is to develop a durable vehicle that has no problem in various customer conditions. Methods: We measured the input load under various conditions of the user by attaching load cell to the body fixing part and towing ball of the towing device. The load in various modes was measured, and the difference between the trailer and the bike carrier type was compared and analyzed. Results: Due to the difference in fixing method and weight between the two types, the trailer has a large longitudinal force and the bike type has a large vertical force. Therefore, it is necessary to durability test method capable of satisfying all longitudinal force and vertical force. Conclusion: We improved the durability test of the towing device by changing the test surface. The new mode has made it possible to shorten the durability test schedule by increasing test efficiency.

• 소성∙가공
• /
• 제26권3호
• /
• pp.137-143
• /
• 2017

In this study, a wear test method was proposed to predict the wear life of the CrN layer coated on the surface of the press tools for manufacturing the auto-parts with ultra high strength steel (UHSS) with a tensile strength of 1.5 GPa. The pin-on-disc type wear test was carried out to confirm the feasibility and the reproducibility of the wear amount according to the test conditions such as the normal force, the sliding velocity, and the sliding speed. The test conditions were obtained from the finite element stamping analysis and the wear simulation. With the wear amount from the wear test, a prediction model of the wear depth in the CrN coating layer was proposed according to the test conditions with the design of experiments such as Taguchi method and the response surface method. The derived prediction model was then compared to the result of the Archard wear model, fully describing that the proposed model can effectively predict the wear life of the press tools for the auto-parts with UHSS.

• 한국자동차공학회논문집
• /
• 제16권6호
• /
• pp.58-64
• /
• 2008

An aluminum radius rod using rheo-forging method has been developed for heavy commercial vehicles to decrease vehicle unsprung weight. To design the shape of the rod, structural simulations are performed using two load cases. To evaluate durability performance of the rods, a test system which has simultaneous 3 axes actuating system is developed. And 3 axes durability test conditions are established based on vehicle field tests. Using the test systems and the conditions, the durability test is carried out and the rods have passed the test conditions of 700,000 cycles. The weight of a developed aluminum radius rod is 4.2kg and it was drastically reduced by 48.8 percent in comparison with the weight of a steel radius rod.

• 한국구조물진단유지관리공학회 논문집
• /
• 제11권3호
• /
• pp.167-175
• /
• 2007

정밀한 구조물의 상태진단 혹은 안전성 평가는 비파괴 시험의 정밀성(Accuracy), 변이성(Variability) 등과 같은 여러 가지 요소에 의하여 좌우된다. 특히 비파괴 시험을 이용한 측정값과 구조물의 상태에 있어서의 불확실성(Uncertainty)은 정밀한 상태진단에 큰 영향을 미친다. 비파괴 시험을 활용함에 있어서의(간접조사) 신뢰할만한 비파괴 장비라면 현 구조물의 상태(피해면적)를 정확하게 나타낼 수 있어야 한다. 본 논문은 현재 사용이 증가되고 있는 비파괴 장비의 올바른 선택과 정확한 구조물의 안전 진단을 위하여, 비파괴장비의 성능 평가에 있어 확률적 기초를 제공한다.