• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.10
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• pp.967-975
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• 2007

A rotordynamic analysis was performed with a dry vacuum pump, which is a major equipment in modern semiconductor and LCD manufacturing processes. The system is composed of screw rotors, lobes picking air, helical gears, driving motor, and support rolling element bearings of rotors and motor. The driving motor-screw rotor system has a rated speed of 6,300 rpm, and was modeled utilizing a rotordynamic FE method for analysis, which was verified through 3-D FE analysis and experimental modal analysis. As loadings on the bearings due to the gear action were significant in the system considered, each resultant bearing load was calculated by considering the generalized forces of the gear action as well as the rotor itself. Each resultant bearing loading was used in calculating each stiffness of rolling element bearings. Design goals are to achieve wide separation margins of lateral and torsional critical speeds, and favorable unbalance responses of the rotor in the operating range. Then, a complex rotordynamic analysis of the system was carried out to evaluate its forward synchronous critical speeds, whirl natural frequencies and mode shapes, unbalance responses under various unbalance locations, and torsional interference diagram. Results show that the entire system is well designed in the operating range. In addition, the procedure of rotordynamic analysis for dry vacuum pump rotor-bearing system was proposed and established.

• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.543-554
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• 1995

This paper describes the improvement of driving stability and the control system for INMEL-VII which is motorized manual wheelchair to satisfy requirements of the disabled The INMEL-VI was based on high maneuverability of the omnidirection drive and safety But the results of field tests about two years showed some problems to the disabled in daily life such as driving stability, Pm switching noise, and rotation of motor without driving command on negative slope. To solve the problems due to an increased DC motor power and applied to direct connection method in INMEL- VII. It improved the driving circuits and set switching frequency to 5KHz to eliminate the switching noise caused by PWM control of DC motor, As compare with the INMEL-VI, INMEL-VII is improved in driving stability by transfer the weight center to forward. The results of field testing proved the improvement of the driving stability and software algorithm It has been estimated to have a hlgh practical use for powered walking aids to the disabled's daily life.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.82-90
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• 2013

In this paper, conducted emission from the MDS(Motor Drive System) of a HEV/EV was analyzed using high- frequency circuit modeling in system-level approach. The conducted emission by PWM process can cause RFI(radio- frequency interference) problems in the AM/FM frequency range. In order to mitigate this conducted emission, a high-frequency equivalent circuit model is proposed by analyzing the fundamental circuits, parasitic components in their parts and connections and non-linear characteristics of IGBTs, high-power capacitors, inverters, motors, high-power cables, and bus bars which are composed of the MDS. It is confirmed that the simulated result by the proposed model is well agreed with measured results in spite of a large-scaled analysis in system level. We are looking forward that this approach can be effectively used in the EMC design of HEV/EV.

• Journal of Korean Physical Therapy Science
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• v.22 no.2
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• pp.1-10
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• 2015

Background : This study verified a correlation between gross motor performance measure (GMPM) and pediatric balance scale (PBS) for children, which are most widely used for assessment of children with cerebral palsy. Methods : The study subjects are 20 children aged between five and 13 who were diagnosed with cerebral palsy. Their mean age was $8.15{\pm}2.96years$ and consists of 15 males and 5 females. The subjects were divided into three groups according to muscle tone and motility disorders and then GMPM and PBS were assessed. In the assessment items in the GMPM, alignment, coordination, dissociated movement, stability, and weight shift were measured. The PBS consists of sitting to standing, standing to sitting, moving between chairs, standing without using hands, standing with one foot, turning 360 degrees, turning to look behind, retrieving object from floor, and reaching forward with outstretched arm while standing. A correlation of the collected data was analyzed using SPSS 18.0 for windows. Results : From Significant correlations were shown between items of GMPM and PBS as well as total scores of GMPM and PBS. Among them, coordination and weight transfer in the GMPM items had a high correlation with the PBS. In addition, the higher the GMPM total score was, the higher the PBS score was. Conclusion : This study result showed a significant correlation between GMPM and PBS, and this relation can be used to pediatric physical examination.

• Journal of Korean Physical Therapy Science
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• v.31 no.1
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• pp.33-45
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• 2024

Background: This study aimed to investigate the effect of elastic band-resistive exercise using audio-visual medium on pain, proprioception, and motor function in adults with chronic neck and shoulder pain. Design: One group pretest-posttest follow-up experimental design. Method: Twenty adult women with neck and shoulder pain voluntarily participated in this study. Elastic band-resistive exercise using audio-visual medium including cervical flexion and extension, shoulder external rotation, and scapular retraction-protraction motions was conducted 5 times a week for 3 weeks. The Numerical Rating Scale, pressure threshold tool, CROM goniometer, and Image J software were used to assess subjective pain level, tenderness threshold (pain), joint position sense error (proprioception), joint range of motion, and postural alignment (motor function), respectively. Result:: The pain intensity and threshold and joint position sense error showed significant decreases after the intervention, whereas the joint range of motion angle revealed significant increases. The postural alignment including forward head posture and rounded shoulder revealed significant improvements after the intervention. Conclusions: Therefore, we suggest that elastic band-resistive exercise through audio-visual medium would be helpful in preventing and managing pain and physical dysfunction in individuals with chronic neck and shoulder pain, and then it would support the development of health management-related online education content.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1256-1263
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• 2015

A novel vector control strategy for a permanent magnet synchronous motor (PMSM) based on the kinetic energy stored in the rotor is proposed in this paper. The novel strategy is composed of two closed loops, in which the current loop is the inner loop, and the kinetic energy serves as the outer loop. The theoretical basis and the design procedure of the two loops are given. The feasibility of the proposed control strategy is verified by experimental results. When compared with traditional vector control strategies, the proposed vector control strategy based on energy feedback has better dynamic performance. In addition, an effective estimation solution for the load variation is put forward.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.8
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• pp.592-599
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• 2014

A torsional vibration at driveline happens seriously at rapid vehicle acceleration. The torsional vibration at driveline can be reduced by optimization of joint angle and yoke phase angle of driveline. But, the joint angle of driveline is changed according to vehicle driving condition as acceleration, deceleration, forward and backward driving, so that excessive vibration is transmitted to vehicle body at specific driving condition. Especially under rapid acceleration condition, vibration transmitted to body could be maximized because excitation force at rapid acceleration is bigger than that at normal driving condition due to changed joint angle. The torsional vibration of driveline can be kept at low level by controlling suspension parameter to minimize rigid axle displacement as well as optimizing joint angles considering the vehicle acceleration condition.

• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.23-27
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• 2006

The power split hybrid powertrain is considered to be one of the most prospective configuration for the hybrid electric vehicle (HEV). Toyota Prius, representing this type of vehicle, showed outstanding performances in fuel efficiency, emission reduction and acceleration. The excellence is largely due to the fact that it utilizes almost all operation modes of HEV. Those modes include ZEV (Zero Emission Vehicle) driving, idle stop, fuel cut-off, power assist, active charging, regenerative braking and so forth. In this paper, a few of the mode operations were simulated using AVL Cruise. Also, control logics to operate the powertrain in each mode were developed. The states of powertrain components were displayed and analyzed. By controlling the three components (engine, motor and generator), it was possible to run the powertrain in several hybrid operation modes.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.89.2-89
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• 2001

Wheel chair bound persons need assistance since there are many steps or curbs or other obstacles blocking their path in the roadways and walkways. Although a step may be small, it may be very difficult for such a person to climb over it. Therefore, we are proposing a power assist wheel chair robot that enables a wheel chair bound person to climb over steps up to about 10 centimeters in height without assistance from others. By using the proposed wheel chair robot, a user can maintain inverse pendulum control after raising its front wheels Then, a user can move forward to the step maintaining the inverse pendulum control, and can climb over the step using motor force of a rear wheel shaft ...

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.319-320
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• 2006

In this paper, automatic sunvisor system is introduced for driver's safety and convenience. This system has the mechanism which keeps the sun off without obstruction of driver's sight. The mechanism can make the sunvisor move forward or rotate left while remaining inside inner roof. The control system consists of a CPU, a motor driver, light sensors, and the algorithm that can control the movement of sunvisor efficiently. When the light sensors take the sun light, they give the signal to the CPU and the CPU calculates the best position of the sunvisor with the information of driver's eyes height. Then, the CPU gives the signal to motors that can move the sunvisor.