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Hz변화에 따른 엔진 밸브 및 밸브시트의 마모에 관한 연구
전경진(Keyoung Jin Chun),홍재수(Jae Soo Hong),이호중(Ho Jung Lee) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The minimization of valve and valve seat wear is a critical pursuit of engine performance. In order to achieve this goal, we developed a new simulator, which can generate and control high temperature up to 900˚C, various speed up to 80Hz during the motion, like a real engine. The wear test rig is thought to be as a valid simulation of the engine valve and valve seat wear process with various speed during engine motions.<br/> The objective of this work focuses on the different wear from two different test speeds (10Hz, 25Hz). It was found that a higher speed (25Hz) cause more wear than a lower speed (10Hz) at the same test conditions (temperature, face force, cycle No.).<br/>
전경진(Keyoung jin Chun),홍재수(Jae Soo Hong) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
The minimization of valve and valve seat wear is a critical pursuit of engine performance. In order to achiere this goal, we developed a new simulator, which can generate and control high temperature up to 900℃, verious speed up to 80㎐ during the motion, like a real engine. The wear test rig is thought to be a valid simulation of the engine valve and valve seat wear process with various speed duting engine motions.
전경진(Keyoung Jin Chun),이호중(Ho Jung Lee) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.3
The functional external fixator system for bone deformity near joints in legs using the worm gear was developed for curing the difference angles in fracture bone and the lengthening bar for curing the difference length in fracture bone. Both experiments and FE analysis were performed to compare the elastic stiffness in several loading modes and to improve the functional external fixator system for the bone deformity. The FE model using the compressive and bending FE analysis was applied to the FE analysis due to the angle differences. The results show that the compressive stiffness value in experiment was 175.43N/㎜; the bending stiffness value in experiment was 259.74N/㎜; compressive stiffness value in FEM was 188.67N/㎜; bending stiffness value in FEA was 285.71N/㎜. The errors between experiments and FEA were less than 10%. The maximum stress (l57MPa) to the angle of clamp was lower than the yield stress (l76.4MPa) of SUS3l6L. The stiffnesses in both axial compressive and bending of the new fixator are about 2 times higher than other products except EBl (2003).
Flexible Flat Cable 생산성 향상을 위한 가압용 히팅롤러의 온도제어개선
전경진(Keyoung Jin Chun),김재학(Jae Hak Kim),이호중(Ho Jung Lee) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.7
Pressure heating rollers with temperature control were mounted to a flat cable laminating machine (FCLM). Pressure heating rollers should be heated up to the setting temperature (175°C) and kept on to producing good quality flexible flat cables (FFC). Existing Pressure heating rollers took more than 70minutes to the setting temperature and did not keep on the setting temperature in production. Temperature controller, electric power controller, material and diameter of rollers and heat capacities were changed to improve the temperature control of the pressure heat rollers for better production of the FFC. Thus, the reaching time to the setting temperature (RT), temperature stability time (TST) and temperature hunting (TH) were measured and compared with the existing pressure rollers case. The RT of A roller was shortened by 50minutes, and B roller was shortened by l5minutes. The TST of A roller was shortened by l3minutes, and B roller was shortened by 8minutes. The THs of both A and B rollers were settled up to ± 5°C. Finally, the productivity of the FCLM and the quality of the FFC were increased.
미세단층촬영기(Micro-CT)를 이용한 전자 근관장 측정기의 정확성에 관한 연구
전경진(Keyoung Jin Chun),김양수(Yang Soo Kim),남태계(Tae Kye Nam) Korean Society for Precision Engineering 2007 한국정밀공학회지 Vol.24 No.8
The length of root canal has to be measured for endodontic treatment. Several electronic apex locators were developed to measure the length of root canal by other researchers. And their accuracies were verified by X-ray or micrometer method. But these methods did not consider the non-linear bends of pulp and had ± 0.5 ㎜ error which was large enough to measure the length of root canal. The purpose of this study is the introduction of a new method to measure the length of root canal and the verification of the accuracy of an electronic apex locator using a Micro-CT. The length of root canal of 6 teeth were measured with the electronic apex locator. When the electronic apex locator reads 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 ㎜ length of the file which was inserted in the hole of the tooth to measure the length of root canal. The average (± Standard deviation) length of root canal of6 teeth measured by the Micro-CT was 0.49 ± 0.03, 0.59 ± 0.04, 0.68 ± 0.03, 0.78 ± 0.03, 0.90 ± 0.04 and 1.01 ± 0.03 ㎜, respectively. The maximum error of the electronic apex locator was 0.06 ㎜.