• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.441-443
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• 2007

In this paper, The authors design the current controller which independently control the d, q axis current transformed by the synchronously rotating d, q axis and a Space Vector Pulse Width Modulation(SVPWM) to steadily control the output DC-Link voltage against the variable load of the three phase PWM converter. Also, This study improves the high power factor, stability, and rapid response by the phase angle control using the digital Phase Locked Loop(PLL).

• The Research Journal of the Costume Culture
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• v.24 no.5
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• pp.600-616
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• 2016

The purpose of this study was to investigate the effects of power blog self-presentation and on-line shopping mall reviews on the word of mouth (WOM) effect and apparel purchasing behavior. Consumers living in Seoul and Gyeonggi received questionnaires. There were 303 usable forms that could be analyzed by descriptive statistics, factor analysis, Cronbach's alpha, and regression analysis. The results were as follows: There was a significant effect of power blog self-presentation such as interactivity, media effect, and business intention on information acceptance through WOM. Power blog self-presentation, such as interactivity and business intention, affect information delivery by WOM significantly. There was a significant effect of review consideration, such as agreement, usefulness, enjoyment, and purity, on information acceptance of WOM. Reviews describing enjoyment, purity, and usefulness affect information delivery of WOM significantly. Business intention, media effect, and purity directly affect apparel-purchasing behavior, and affect the WOM effect as a mediator variable and then purchasing behavior. Whereas, interactivity, overstatement, and enjoyment affect the WOM effect as a mediator variable, and then affect overall purchasing behavior. Therefore, fashion firms consider active interaction with power blog visitors and promote the way of enjoying with fun through review of apparel on-line shopping mall when they try to implement viral marketing with WOM effect.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.513-516
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• 2004

In this paper, a PWM Cuk AC-AC converter for power quality improvement of custom power is presented. The PWM Cuk AC-AC converter that is used in VVCF applications such as AC line conditioner, phase shifter is modelled by using complex circuit DQ transformation whereby the static characteristics equations such as voltage gain and power factor is analytically obtained. Finally, the PSIM simulation show the validity of the modelling and analysis.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.10
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• pp.625-633
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• 2004

This paper proposed a boost input type single stage resonant power supply for driving magnetron device. The proposed power supply can control both input power factor and output power at the same time. Also, because ZVS is achieved using the resonance between leakage inductance and resonant capacitance, switching losses are drastically reduced. To prevent breakdown or moding phenomenon of the magnetron due to excessive starting voltage, variable frequency ignition method is also proposed. Experimental results for the prototype power supply are presented and discussed to verify the validity of the proposed power supply.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.150-157
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• 2005

This paper presents the simulation modeling and analysis of variable wind speed turbine system(VWTS) using the doubly fed induction generator(DFIG) connected the back to back converter system in the rotor side. In the simulation, using the model system which has the 660[kW] rated power, blade control and the dual converter system are modeled for verifying the control characteristics. The VWTS is controlled by the optimal pitch angle for maximum output power under the rated wind speed, and for the rated output power over the rated wind speed. And also power factor is controlled by the reactive power. To verify the effectiveness of the proposed method, simulation results are compared with the actual data from the V47 VWTS located in Hangwon wind farm in Jeju-Do. According to the comparison of these results, this method shows excellent performance.

• International Journal of Advanced Culture Technology
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• v.6 no.3
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• pp.163-172
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• 2018

The power train of hydro-mechanical continuously variable transmission(HMCVT) for the middle class forklift makes use of an hydro-static unit, hydraulic multi-wet disc brake & clutches and complex helical & planetary gears. The complex helical & planetary gears are a very important part of the transmission because of strength problems. The helical & planetary gears belong to the very important part of the HMCVT's power train where strength problems are the main concerns including the gear bending stress, the gear compressive stress and scoring failures. The present study, calculates specifications of the complex helical & planetary gear train and analyzes the gear bending and compressive stresses of the gears. It is necessary to analyze gear bending and compressive stresses confidently for an optimal design of the complex helical & planetary gears in respect of cost and reliability. This paper not only analyzes actual gear bending and compressive stresses of complex helical & planetary gears using Lewes & Hertz equation, but also verifies the calculated specifications of the complex helical & planetary gears by evaluating the results with the data of allowable bending and compressive stress from the Stress - No. of cycles curves of gears. In addition, this paper explains actual gear scoring and evaluates the possibility of scoring failure of complex helical & planetary gear train of hydro-mechanical continuously variable transmission for the forklift.

• Journal of the Ergonomics Society of Korea
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• v.36 no.5
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• pp.559-568
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• 2017

Objective: The aim of this study is to investigate the effective managerial factors influencing dose reduction of the nozzle dam installation and removal tasks ranking within top 3 in viewpoint of average collective dose of nuclear power plant maintenance job. Background: International Commission on Radiation Protection (ICRP) recommended to reduce unnecessary dose and to minimize the necessary dose on the participants of maintenance job in radiation fields. Method: Seven sessions of nozzle dam installation and removal task logs yielded a multiple regression model with collective dose as a dependent variable and work time, number of participants, space doses before and after shield as independent variables. From the sessions in which a significant reduction in collective dose occurred, the effective managerial factors were elicited. Results: Work time was the most important factor contributing to collective dose reduction of nozzle dam installation and removal task. Introduction of new technology in nozzle dam design or maintenance job is the most important factor for work time reduction. Conclusion: With extended task logs and big data processing technique, the more accurate prediction model illustrating the relationship between collective dose reduction and effective managerial factors would be developed. Application: The effective managerial factors will be useful to reduce collective dose of decommissioning tasks as well as regular preventive maintenance tasks for a nuclear power plant.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1664-1667
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• 2005

The main function of Ball-Stop part is to operate power shift for vehicle with more than 5 ton when a driver changes gear using suitable force. This paper presents the implementation of a DFSS(Design For Six Sigma) for robust design of Ball-Stop part of power shift. The factors influencing Ball-Stop part performance is derived to find control factor. Based on this factor, contact force between head and detent pin analysis is performed to get optimal factor is analyzed and compared with contact force test result to verify reliability of design. This makes clear the reason why the proposed one is necessary and the role of DFSS.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.216-219
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• 2003

The resonant inverter is widely used for induction heating, electronic ballast and supersonic motor driving circuit. In the meantime, control techniques of PWM, PFM etc.. are mainly applied to control the output power of the resonant inverter. But, in the case of using the half bridge resonant inverter, it is difficult to control the output power by PWM, because its main circuit does not provide the load free-wheeling mode. Therefore, PAM or PFM was usually applied to control output power of half bridge resonant inverter. However, PAM needs a variable DC voltage source, which makes the system structure more complex. On the other hand, in case of PFM, efficiency is declined by operation with poor power factor. This paper Proposed the novel half bridge resonant inverter which can provide the load free-wheeling mode. Also its analysis results for PWM operation with unity fundamental power factor are Presented and compared with other resonant inverters using PWM and PFM.

• Advances in materials Research
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• v.4 no.1
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• pp.31-44
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• 2015

This paper presents a simple n-order four variable refined theory for buckling analysis of functionally graded plates. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations of the present theory is reduced, and hence, makes it simple to use. The present theory is variationally consistent, uses the n-order polynomial term to represent the displacement field, does not require shear correction factor, and eliminates the shear stresses at the top and bottom surfaces. A power law distribution is used to describe the variation of volume fraction of material compositions. Equilibrium and stability equations are derived based on the present n-order refined theory. The non-linear governing equations are solved for plates subjected to simply supported boundary conditions. The thermal loads are assumed to be uniform, linear and non-linear distribution through-the-thickness. The effects of aspect and thickness ratios, gradient index, on the critical buckling are all discussed.