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Study on Exhaust Valve and Seat Insert Wear Depending on Fuel Type
홍재수,전경진,김양수 한국정밀공학회 2012 International Journal of Precision Engineering and Vol.13 No.2
This study used a dedicated wear tester to verify the cause and amount of wear depending on fuel type such as LPG and gasoline. Test conditions for general commercial vehicles, such as number of cycles (2 × 106), test speed (25Hz),temperature (350°C), and force (1960N) were applied to the specimens. This study utilized LPG and gasoline as test fuels. The maximum depth of wear (Dmax) of the exhaust valve and the seat insert was 74.7 (± 3.9)μm and 82.9 (± 2.9)μm,respectively, in the case of the test using LPG, and 64.6 (± 4.0)μm and 59.4 (± 1.2)μm, respectively, in the case of the test using gasoline. The result of the analysis performed on the compositions of the combustion products appearing on the exhaust valve and the seat insert using EDS (Energy Dispersive Spectroscopy) indicated that, in the case of the test performed with LPG, O and S were detected from the test specimen, and that in the case of the test specimen performed with gasoline, O, P, and Ca were detected from the test specimen. The analysis results from the composition of the seating faces indicated that the seating face of the exhaust valve had Cu and Mo existing only in the seat insert regardless of the type of fuel used. In addition, Si and Mn, which existed only in the exhaust valve, were detected in the seating face of the seat insert. The mean Dmax of the exhaust valve and the seat insert, for which the test was performed with LPG fuel, was greater than that of the exhaust valve and the seat insert for which the test was performed with gasoline fuel, 14.5% and 29.4%,respectively. The adhesive wear and tribochemical reaction products were observed regardless as to whether the fuel type was LPG or gasoline. However, the abrasive wear was observed only at the seating face of the seat insert for which the test was performed with LPG fuel. From the analysis performed based on the above results, it is thought that since LPG fuel has less combustion products that act as a gum component that lubricates the valve and the seat insert seating faces than gasoline fuel. The direct metal-to-metal collision between the valve and the seat insert seating faces may generate more particles with LPG fuel. Therefore, The abrasive wear was observed only in the specimen for the test performed with LPG fuel, however it was not observed in the specimen for the test performed with gasoline fuel.
Study of Muscle Strength Imbalance at the Shoulder Joint between the Young and the Old
홍재수,전경진,김종현,박병규,홍정화 한국정밀공학회 2013 International Journal of Precision Engineering and Vol.14 No.12
This study examined muscle imbalance in the cases of isokinetic movement of the shoulder joint, targeting the young and the old. The experiment was divided into the dominant and non-dominant sides and consisted of flexion, extension, abduction, adduction, external rotation, and internal rotation. Regarding the angular velocity, the peak torque was measured for the equal condition of 30, 60, and 120 deg/s. The concentric and eccentric muscular strengths were measured based on each motion. This study showed that concentric movement tended to decrease the peak torque on the dominant and non-dominant sides alike by increasing the angular velocity,whereas an eccentric movement had a tendency to boost the peak torque by increasing the velocity except for the dominant external rotation. In the case of the young, most of the motion showed that the dominant side had a higher peak torque than the non-dominant side regardless of the angular velocity. The results from the elderly were different from the young, and the non-dominant side tended to have a higher peak torque than the dominant one regardless of the angular velocity. According to the Antagonistic Strength relationships(Concentric) in the young and the old, young people’s flexion/ extension ratio was 3 ~ 13%, abduction/adduction 1 ~ 16%, and external rotation/internal rotation 5 ~ 10%. The data from the elderly showed that the ratio of abduction/adduction under concentric contraction ranged from 20 to 31%, which was higher than that reported previously. The elderly showed an imbalanced muscle tendency. This result is expected to provide a useful basic guideline for measuring the shoulder function of the young and old, and consisted rehabilitation equipment and its programs.
동작분석을 활용한 상지재활기기의 Arm support 디자인에 관한 연구
홍재수(Jaesoo Hong),심주현(Joohyun Sim),김종현(Jonghyun Kim),전경진(Keyoungjin Chun) 한국HCI학회 2012 한국HCI학회 학술대회 Vol.2012 No.1
최근 한국은 고령인구와 함께 뇌졸중 환자가 급속히 증가하고 있으며, 이로 인한 뇌졸중 환자의 재활운동이 중요시 되고 있다. 그러나 뇌졸중의 재활장비 개발에 대한 연구는 미진한 실정이다. 본 연구에서는 뇌졸중 환자의 재활에 일반적으로 사용되는 장비인 Grahamizer의 arm support에 대한 운동특성연구 등을 통하여 최적화된 arm support의 디자인 가이드라인 제시를 연구목적으로 한다. 본 연구에서는 다음과 같은 디자인 평가 방법을 실시 하였다. (1) 중심축의 변화에 따른 Arm support 동작분석, (2) Arm support의 길이 변화에 따른 동작분석. 실험 결과로 길이는 220mm, 중심축 위치는 손잡이 방향 쪽의 팔 받침대가 시작하는 곳에서 사용자 방향으로 100mm(3번 위치)에 위치했을 시 최적의 운동궤적이 나왔다. 향후 본 연구의 평가방법이 상지재활기기의 개발에 사용될 수 있을 것으로 기대된다. In this recent, population of elderly and stroke patients has increased in Korea. So, rehab exercise of stroke patients has been increased importance. However, the case study of developing rehabilitation equipment for stroke patients is still lack. The grahamizer is rehabilitation equipment of stroke patients generally. So, the aim of this study is suggest for design guideline through exercise Characteristic about arm support of grahamizer. In this study, usability evaluation of Arm support design was performed.; (1) Motion analysis of arm support by variation of central axis, (2) Motion analysis of armrest by variation of armrest's length. The results of this study showed that length of armrest: 220mm, Position of central axis: 3. In the results of this study, evaluation method of this study is expected to be used in development of upper limb rehabilitation equipment.
높이 조절 샤워의자의 개발을 위한 설계 가이드라인 분석
홍재수(Jaesoo Hong),전경진(KeyoungJin Chun) 한국HCI학회 2014 한국HCI학회 학술대회 Vol.2014 No.2
고령자에게 있어서 샤워는 삶의 질과 관련된 중용한 행위중에 하나이다. 본 연구에서는 고령자용 높이 조절 샤워의자를 개발하기 위한 설계 가이드라인을 제시하기 위한 것이다. 첫째, 높이 조절 샤워의자를 인체 치수를 적용하여 디자인하였다. 둘째, 기존 해외 제품을 가격, 형상, 기능 등을 분석하였다. 고령친화제품개발의 사례연구는 고령자를 위한 제품개발의 프로세스를 체계화함에 따라 타 복지기구 및 고령자들을 위한 다양한 종류의 생활지원기기뿐만 아니라 다른 관련 산업에도 응용이 가능한 요소 기술을 확보할 수 있었다. The shower to elderly people is an important activity that related to the quality of life. In this study, to develop a height adjustable shower chair for elderly people, firstly, a height adjustable shower chair was designed by applying human dimensions. Secondly, existing international products were analyzed the prices, features, and performance. Thus, the elderly a height adjustable shower chair was developed by ergonomic design procedure of three steps.