• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.804-806
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• 2003

In these days the Vacuum Circuit Breaker(VCB) is used in most medium voltage level because VCB has merits of simple structure, long life, free maintenance and environment friendly characteristics. Most of VCBs adopt mechanical spring drive mechanism to operate vacuum interrupter, but this mechanism is composed of many components and needs frequent maintenance works. In this paper, we study about the VCB drive mechanism with Permanent Magnet Actuator (PMA). Design methods and design flows about PMA are presented. The magnetic equivalent circuit is used for elementary and detailed design to determine the size of PMA. Finite Element Method (FEM) analysis is performed to evaluate the behavior characteristics of PMA in both static and transient state. Finally we manufacture sample PMA and verify FEM analysis through experiments.

• International Journal of Advanced Culture Technology
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• v.10 no.2
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• pp.116-121
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• 2022

Digital technology has now pervaded and become an inseparable part of our daily life. The art museum sector is evolving into a business model that adapts to the new digital format due to the requirement for survival and development. This study examines the development state of China's art museum industry and investigates the current business model innovation trend in the art museum industry from three perspectives: reorganization and development of the art museum industry's business model theory; reconstruction of the art museum industry's display and marketing logic; and innovation of the art museum industry's operation mechanism, based on a systematic assessment of domestic and international research. This research can provide reference value for digital technology to drive the innovation of business model in art museum industry. Moreover, the study has important reference significance for the development strategy of art museum industry.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.8
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• pp.759-765
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• 2016

The PTO (Power Take-Off) shaft for aircraft, with welded construction using multiple thin membranes, was developed in the 1950s to improve the elasticity of the part. As it is lightweight, stable at high speeds, and has good flexibility, it is used in most of the fighter aircraft. It connects the AMAD (aircraft mounted accessory drive) gearbox with the EMAD (engine mounted accessory drive) gearbox and transmits the rotational power between them. It operates in the high speed range of 10,000-18,000 rpm. In this study, the safety of the PTO shaft made of Ti alloy was investigated using finite element analysis, and the ability to transmit power was demonstrated through a high-cycle fatigue test conducted in a laboratory. Further, the life of the ball joints of the aircraft under high-cycle fatigue test conditions was predicted, and the wear characteristics were analyzed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.425-431
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• 2011

The harmonic distortion level may be significant in electric propulsion systems, as the main loads usually are variable speed propulsion/thruster drives. Distortion of currents and supply voltage waveforms may lead to: Increased power dissipation(losses) in equipment connected to the network, such as generators, motors, transformers, cables, etc., from the harmonic currents, may cause overheating and deterioration of the insulation, and reduced life time of the equipment. In this paper introduced the canceling method of harmonic currents by a multipulse drive with phase shifting transformer. The simulation results indicated a good speed response to the middle speed range of electric propulsion motor. And also, THD(total harmonic distortion) and torque ripple could be reduced in comparing the 12-pulse drive with 6-pulse drive.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.10
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• pp.339-345
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• 2020

Human resource is considered as an important resource that enables organizations to achieve competitive advantage. As such, it is important to have engaged employees to drive the strategic objectives of the organization. The study focuses on variables that can promote employee engagement. Work-life balance and employee engagement have received attention in both academia and practice. Engaged employees are crucial in the achievement of the strategic objectives of organizations. Besides, the role of religious orientation in life and work has been gaining attention from management scholars. The paper attempts to fill the research gap by developing a conceptual model and propositions for empirical testing. Specifically, the study proposes that work-life balance is expected to act as a mediator in the relationship between religiosity and employee engagement. Furthermore, religiosity is included as a moderator since religious belief can strengthen the positive relationship between work-life balance and employee engagement. A systematic literature review was carried out. A framework and propositions for future studies have been developed. The proposed framework provides direction for scholars to empirically test the indirect relationship between work-life balance, religiosity and employee engagement. Empirical testing of the framework could provide insights into how work-life balance and religiosity promote employee engagement.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.7
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• pp.475-484
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• 2018

The propulsion control device of an electric railway vehicle is a key main component corresponding to an engine of an automobile, and a device for controlling this is a device called a GDU (Gate Drive Unit). Also, when the frequency of failure of the propulsion control system was analyzed, the nonconformity ratio of GDU was the highest. GDU was not able to access core technologies due to the introduction of foreign products, and there were general problems with overall maintenance activities due to discontinuation of GDU of the manufacturer. The GDU has reached the end of its life with 23 to 14 years of long-term use.In order to solve these problems, this study was designed to identify the proper life span by analyzing compatible GDU's acquisition and failure, and to improve the existing system of maintenance focusing on health inspection. Maintenance of the components with a short life span compared to the entire service life is essential. Most foreign parts introduced at the beginning of the construction are not replaced due to technical problems or long-term operation. However, due to the characteristics of railway vehicles with a long life span of more than 25 years, it is necessary to maintain them for a long period of time. The study should be more concrete and empirical. The replacement type GDU of capacitors was able to easily measure the life of the capacitance by removing the capacitor modules, measure the life span of each unit test, and accurately perform preventive maintenance of the capacitor.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.247-251
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• 2001

Universal motors are mainly used for vacuum cleaner application. There are a lot of researches on SRM that applys home appliance throughout the world. The manufacturing cost of SRM drive makes it hard to expand its application to home appliance. This paper presents Single Phase SRM for the vacuum cleaner that has advantge in cost and performance over conventional universal motor. This paper proposes new power device driving scheme by using SRM switching characteristic. The driving scheme is very simple and inexpensive. Dwell Time Control method is used for the minimum switching loss of power device. The switching frequency of power device is less than 4.5kHz at 45,000rpm. By use of this scheme, power device based on very small switching losses can be used on SRM drive. Also, the biggest problem in single phase SRM is starting, this paper shows a new starting algorithm with two hall sensors, accelerating and running sensors, respectively. Finally, the proposed Single Phase SRM achieves higher efficiency and long life time compared to universal motor. Its life time is more than 1500 hours. Its life time is extended 4 times than that of conventional motor and its suction power is increased $20\%$ at the same volume of conventional universal motor.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.185-194
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• 1998

In this study, the rotary bending fatigue test was carried out with two kinds of material, S43C and S50C, using in the Front engine and Front drive wheels(F.F.) of vehicle. The one part of specimens was heated by high frequency induction method(about 1mm depth and $H_RC$ 56~60) and tested environment temperature were $-30^{\circ}C$, $+25^{\circ}C$ and $+80^{\circ}C$ in order to look over the influence of the heat treatment and the temperatures. In the experimented result at $+25^{\circ}C$ and $+80^{\circ}C$, the fatigue life of non-heated specimens were decreased about 35%, but that of heated specimens were decreased about only 5% at $+80^{\circ}C$ more than at $25^{\circ}C$. And in the experiment result at $-30^{\circ}C$ and $+25^{\circ}C$, the non-heated and heated specimens were about 110%, 120% higher fatigue life at $-30^{\circ}C$ than at the $+25^{\circ}C$ each other. On the other hand, the fatigue crack propagation rate of S50C was higher than that of S43C.

• Korean Journal of Applied Biomechanics
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• v.20 no.2
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• pp.155-165
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• 2010

The purpose of this study was to analyze kinematic quantitative factors required of a forehand counter drive in table tennis through 3-D analysis. Four national table tennis players participated in this study. The mean of elapsed time for total drive motion was $1.009{\pm}0.23\;s$. At the phase of impact B1 was the fastest as 0.075 s. This may affect efficiency in the initial velocity and spin of the ball by making a powerful counter drive. The pattern of center of mass showed that it moved back and returned to where it was then moved forward. At the back swing, lower stance made wide base of support and a stronger and safer stance. It may help increasing the ball spin. Angle of the elbow was extended up to $110.75{\pm}1.25^{\circ}$ at the back swing and the angle decreased by $93.75{\pm}3.51^{\circ}$ at impact. Decreased rotation range of swinging arm increased linear velocity of racket-head and impulse on the ball. Eventually it led more spin to the ball and maximized the ball speed. Angle of knee joint decreased from ready position to back swing, then increased from the moment of the impact and decreased at the follow thorough. The velocity of racket-head was the fastest at impact of phase 2. Horizontal velocity was $7796.5{\pm}362\;mm/s$ and vertical velocity was $4589.4{\pm}298.4\;mm/s$ at the moment. It may help increase the speed and spin of the ball in a moment. The means of each ground reaction force result showed maximum at the back swing(E2) except A2. Vertical ground reaction force means suggest that all males and females showed maximum vertical power(E2), The maximum power of means was $499.7{\pm}38.8\;N$ for male players and $519.5{\pm}136.7\;N$ for female players.

• Korean Journal of Applied Biomechanics
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• v.26 no.1
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• pp.21-30
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• 2016

Objective: This study aimed to examine the characteristics of joint kinematics and synchronicity of rowing motion between elite and non-elite rowers. Methods: Two elite and two non-elite rowers performed rowing strokes (3 trials, 20 strokes in each trial) at three different stroke rates (20, 30, 40 stroke/min) on two stationary rowing ergometers. The rowing motions of the rowers were captured using a 3-dimensional motion analysis system (8-infrared camera VICON system, Oxford, UK). The range of motion (RoM) of the knee, hip, and elbow joints on the sagittal plane, the lead time ($T_{Lead}$) and the drive time $T_{Drive}$) for each joint, and the elapsed time for the knee joint to maintain a fully extended position ($T_{Knee}$) during the stroke were analyzed and compared between elite and non-elite rowers. Synchronicity of the rowing motion within and between groups was examined using coefficients of variation (CV) of the $T_{Drive}$ for each joint. Results: Regardless of the stroke rate, the RoM of all joints were greater for the elite than for non-elite rowers, except for the RoMs of the knee joint at 30 stroke/min and the elbow joint at 40 stroke/min (p < .05). Although the $T_{Lead}$ at all stroke rates were the same between the groups, the $T_{Drive}$ for each joint was shorter for the elite than for the non-elite rowers. During the drive phase, elite rowers kept the fully extended knee joint angle longer than the non-elite rowers (p < .05). The CV values of the TDrive within each group were smaller for the elite compared with non-elite rowers, except for the CV values of the hip at all stroke/min and elbow at 40 stroke/min. Conclusion: The elite, compared with non-elite, rowers seem to be able to perform more powerful and efficient rowing strokes with large RoM and a short $T_{Drive}$ with the same $T_{Lead}$.