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전경진(Keyoung Jin Chun),이호중(Ho Jung Lee),정동택(Dong Teak Chung) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.2
Tooth morphology is the most important scientific aspect of dental medicine in regards to the treatment and study of teeth attrition relating to the absence of teeth due to dental caries or the occlusion of teeth due to external force. Most of the studies have focused on the external morphology in cutting teeth regardless of sex and age. However, the importance of internal morphology in the treatment of damaged teeth has been increased. Therefore, this study established the measurement criteria for the morphology of the mandibular first premolar which had never been presented, in order to investigate the external and internal morphologies of mandibular first premolars, and introduced a non-destructive method such as a microcomputed tomogrphy. Mandibular first premolars in superlative state were taken from molars of middle aged males and females and used as specimens for this study. Criteria relating to the internal and external morphology measurements were established to quantify the length of the teeth in identical state. Two dimensional image data for the selected mandibular first premolar were obtained by taking the image of each 0.022㎜ section, which is perpendicular to the vertical direction using the microcomputed tomography. The Vworks program was applied to measure the length of each morphological part according to the set measurement criteria. These measured data were compared with the data presented by G. V. Black and the internal and external morphologies of the teeth of middle aged Koreans were also compared according to gender. In addition, the methodology for measurement of the mandibular first premolar was presented and according to this, the standardized mandibular first premolars of middle aged Korean males and females were made by using a rapid prototyping system.
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.
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).