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배터리로 구동되는 이동 로봇의 에너지 소모 최소화를 위한 3-구간 속도 제어
김병국,김종희,Kim Byung-Kook,Kim Chong-Hui 제어로봇시스템학회 2006 제어·로봇·시스템학회 논문지 Vol.12 No.3
Energy of wheeled mobile robot is usually supplied by batteries. In order to extend operation time of mobile robots, it is necessary to minimize the energy consumption. The energy is dissipated mostly in the motors, which strongly depends on the velocity profile. This paper investigates various 3-step (acceleration - cruise - deceleration) speed control methods to minimize a new energy object function which considers the practical energy consumption dissipated in motors related to motor control input, velocity profile, and motor dynamics. We performed an analysis on the energy consumption various velocity profile patterns generated by standard control input such as step input, ramp input, parabolic input, and exponential input. Based on these standard control inputs, we analyzed the six 3-step velocity profile patterns: E-C-E, P-C-P, R-C-R, S-C-S, R-C-S, and S-C-R (S means a step control input, R means a ramp control input, P means a parabolic control input, and E means an exponential control input, C means a constant cruise velocity), and suggested an efficient iterative search algorithm with binary search which can find the numerical solution quickly. We performed various computer simulations to show the performance of the energy-optimal 3-step speed control in comparison with a conventional 3-step speed control with a reasonable constant acceleration as a benchmark. Simulation results show that the E-C-E is the most energy efficient 3-step velocity profile pattern, which enables wheeled mobile robot to extend working time up to 50%.
김병국,나기상,신시옥,Kim, Byung-Kook,Rha, Ki-Sang,Shin, See-Ok 대한기관식도과학회 2000 大韓氣管食道科學會誌 Vol.6 No.1
Objectives : This study was designed to compare the morphological changes in the nasal, tracheal and main bronchial mucosa in rats exposed to 0, 0.3, 0.6, 0.9 and 1.2 ppm ozone for 7 days, 6 hours per day. Materials and Methods : We observed the nasal, tracheal and main bronchial mucosa in rats exposed to 0, 0.3, 0.6, 0.9 and 1.2 ppm ozone for 7days, 6hours per day with LM, SEM and TEM. Results : In light microscopy, influx of inflammatory cells, epithelial hyperplasia, loss of cilia and increased goblet cells were observed in all rats except those exposed to 0.3 ppm. these findings increased with the increase of ozone concentration, but there were no significant differences among the nasal, tracheal and main bronchial mucosa in rats exposed to the same ozone concentration. In scanning electron microscopy, a loss of cilia was observed in rats exposed to 0.3 ppm in some sections and 0.6 ppm and 1.2 ppm in all sections. In transmission electron microscopy, vacuolization of epithelial cells was observed in rats exposed to 0.3 ppm in some sections and 0.6 ppm in all sections. These results suggest that electron microscopic observation is necessary to study morphology of airway mucosa in rats exposed to ozone below 0.3 ppm. And also the morphological changes in nasal septal epithelium may reflect those of tracheal and bronchial epithelium after high concentration ozone-exposure.
접촉 조건에 따른 C/C-SiC-Cu복합재와 Al/SiC복합재의 마모 특성에 관한 연구
김병국(Byung-Kook Kim),신동갑(Dong-Gap Shin),김창래(Chang-Lae Kim),구병춘(Byeong-Choon Goo),김대은(Dae-Eun Kim) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.1
디스크 브레이크의 온도는 제동 시 변할 수 있으며 이러한 표면 온도의 변화는 마찰/마모 특성에 영향을 줄 수 있다. 따라서 효율이 우수한 브레이크 개발을 위해서는 브레이크 소재의 마찰/마모 특성에 대한 이해가 필요하다. 본 연구에서는 디스크 브레이크 시스템에 사용되는 C/C-SiC-Cu복합재와 Al/SiC복합재에 대하여 표면 온도와 접촉압력에 따른 마찰/마모 특성을 비교하였다. 이를 위해 온도 및 하중조절이 가능한 pin-on-reciprocating방식의 마찰실험기를 사용하였다. 실험결과, 마찰은 온도와 거리에 따라 현저하게 변하였다. 또한 마모로 인하여 생성된 입자가 접촉 압력에 의해 표면에 뭉쳐져 transfer layer가 형성되었고, 표면 거칠기가 증가하였다. 이러한 연구 결과는 다양한 조건에서 작동하는 브레이크 시스템개발을 위한 기초자료로 활용될 수 있을 것이다. The surface temperature of disc brakes varies during braking, which can affect the friction and wear behavior of braking systems. In order to develop an efficient braking system, the friction and wear behaviors of brake materials need to be clearly understood. In this work, the friction and wear behavior of the C/C-SiC-Cu composite and the Al/SiC composite, which are used in disc braking systems, were investigated. Both the surface temperature and contact pressure were studied. A pin-on-reciprocating tribotester was used for this purpose, in order to control temperature and load. Results showed that the friction varied significantly with temperature and sliding distance. It was found that a transfer layer of compacted wear debris formed on the wear track of the two materials. These layers caused the surface roughness of the wear track to increase. The outcome of this work is expected to serve as a basis for the development of braking systems under various operating conditions.