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조호준(Hojoon Cho),조종두(Chongdu Cho),김명구(Myoung-Gu Kim),맹주원(Juwon Maeng),이용산(Yongsan Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Hot spot phenomenon that occurs, during judder vibration, is locally concentrated heat due to friction between brake disk and pad. It is important to understand the reason behind hot spot phenomenon, for reduction of judder vibration. In this experimental study, experiments were performed in accordance with rotation speed of brake disk, pressure of master cylinder and pad length for achieving different aspects of hot spot phenomenon. Temperature distribution of hot spot was obtained by using the infrared camera. As the hot spot occurred, vibration was measured and frequency analysis was performed. Finite element analysis of thermal deformation of disk was performed by using temperature distribution that was achieved by experimental results. It was observed that the excitation frequency band of frictional contact and frictional force mainly affects the hot spot phenomenon.
디스크 브레이크에서 열섬 천이가 저더 현상 발생에 미치는 영향
조호준(Hojoon Cho),조종두(Chongdu Cho),맹주원(Joowon Maeng),이용산(Yongsan Lee),조기철(Kicheul Cho) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Hot judder phenomenon makes serious problems such as to be uneasiness to drivers or to decrease braking force of vehicle. Because judder vibration makes high magnitude vibration occurrence and thermal problem of brake disk in accordance with hot spots growth at the same time. Therefore it is necessary to reduce or eliminate judder phenomenon by understanding and analyzing origins of hot spot phenomenon. In this experimental study, mode shapes and frequencies related to hot spots were measured by modal testing. For increasing results of modal testing, mode analysis was calculated by finite element analysis. For coupled analysis of disk thickness variation (DTV) and judder vibration, temperature distribution of brake disk, DTV and vibration were measured by interval of 30 seconds in accordance with pressure of master cylinder at the same time. These were conducted by chassis-dynamometer. Hot spot measurements were photographed by using infrared camera. As results, coupled analysis of DTV and judder vibration was performed and relationship between temperature distribution and mode shapes was analyzed.
Printing the products: An overview of the Three Dimensional Printing (3DP) process
Mohib(모힙),Chongdu Cho(조종두) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
This paper work presents an overview of the three dimensional printing process (3DP), its features, capabilities and applications. 3DP has generated a lot of interest in recent years as a tool for creating rapid prototypes, and thereby reducing the design cycle of product development. With the advances in the field, nowadays, it is being used for many purposes other than rapid prototyping, and in fields as diverse as medicine, automobile engineering and art-restoration. Several such case studies covering a wide range of applications are discussed in this paper work. It also analyses the future of 3DP in view of recent developments, and its transformation from rapid prototyping to rapid manufacturing.
자기변형현상을 이용하는 MEMS 작동기의 유한요소 모델링
시호문(Ho-Mun Si),조종두(Chongdu Cho) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.8
This paper describes finite element models for MEMS actuators utilizing magnetostriction. The models are proposed to resolve the difficulties encountered in the finite element modeling of magnetostrictive thin film structures of large aspect ratios. They are applied to the bending of the cantilever and the membrane structure coated with magnetostrictive thin films. Their results are compared with those obtained form theoretical calculations and experiments elsewhere.
송중록(Zenglu Song),조종두(Chongdu Cho),반강(Qiang Pan),김재민(Jaemin Kim),김웅지(Woongji Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
A wireless magnetic torque sensor is utilized to measure the torque generated in the rotating shaft in magnetic field without connecting to the shaft by any wire. In this study, a new wireless magnetic torque sensor was introduced. The structure of the sensor was explained detailed as well as its operation principle. Resulting from the torque measurement experiment results, the sensor was proven to measure the generated torque effectively. Compared with traditional contact torque sensor, the wireless one has low cost and good environment adaptation ability. Moreover, the intractable wrapping wires around the shaft are removed in this design. Hence the wireless torque sensor may be expected as a possible sensing device for many applications, such as the electric assisting rotation system in automobiles, the torque sensing system in motors, the arm rotation system in robotics and so on.