• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.528-532
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• 1987

Closed-loop fiber-optic gyroscope with linear scale factor for a wide dynamic range is demonstrated using a gating process and two-harmonic phase modulation, of which the second harmonic is obtained by a frequency doubler. Also the effects of the second harmonic and duty cycle of gating signal on the linearity of scale factor are estimated theoretically and compared with the measured data. The experimental results show the best linearity of scale factor is about 0.5% within the rotation rate 90.deg./sec. The closed-loop fiber-optic gyroscope with gated two-harmonic phase modulation can be used in the application demanding less sensitive performance and modest scale factor linearity.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.242-245
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• 1995

In this paper the multiple three rectifiers for the power factor correction are proposed, analyzed and designed. The multiple three phase rectifiers draw sinusoidal ac currents from the ac voltage sources with nearly unity input power factor and operate with PWM making the control circuit simple and system cost low. Outstandingly it reduces the rated power capacity of devices and the input filter size by reducing input current ripples. Moreover design rules can be obtained from input and output current equations. With the proposed rules, input power factor and output power capacity are determined approximately. Finally these design rules are verified with computer simulations.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.10
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• pp.555-569
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• 2020

This study examines the impact of corporate tax, a fiscal measure along with trade liberalization and research and development on total factor productivity for a panel of 153 industrial firms listed on the Pakistan Stock Exchange over the period 1997-2017. For empirical analysis, we employ the system generalized method of moment estimator. In the first step, we estimate industrial production function and the results reveal that raw material, industrial labour force and energy play vital role in enhancing industrial production. Whereas, industrial capital exerts negative impact on industrial output. We also measured total factor productivity using the production elasticities. In the second step, we examine the impact of corporate tax, trade liberalization and research and development on total factor productivity. The results indicate that higher level of corporate tax exerts negative impact on total factor productivity. The findings reveal that higher corporate taxation discourages industrial firms to undertake research and development thereby exerting adverse impact on total factor productivity of firms. The impact of trade liberalization proxied by average tariff is positive while customs duty and sales tax negatively impact firm-level total factor productivity. These findings provide useful insights for managers, investors and policy makers in Pakistan.

• Journal of Digital Convergence
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• v.11 no.1
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• pp.1-11
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• 2013

This study attempt to explore how much characteristics of personal and institutional of staffs in shelter for teenage runaway influence to client's violence, and which factor of them are relative to client's violence. For this aims, we carried out a survey, survey subjects in shelter for teenage runaway participated in this research. T-test and variance analysis attempted to compare degree of violence experience of respondents by personal and institutional characteristics. According to result of analysis, age in the midst of personal characteristics is meaning difference and duty-time and type of shelter in the midst of institutional characteristics revealed meaning difference. Next, Multi-regression analysis tried to explore relative factor influencing on client's violence. The results, age in the midst of personal characteristics is relative with physical violence, duty-year in present institution is relative with etc harm. Also, duty-time per week of institutional characteristics is relative all with four type of violence. Type of shelter is relative with property harm, emotional violence and etc harm. Counseling time during duty is relative with physical violence. Above results provide basic data to find ways preventing client's violence to staffs in shelter for teenage runaway.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.2
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• pp.199-208
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• 2012

This paper proposes a quasi Z-source DVR(Dynamic Voltage Restorer) system with a series connection of the output terminals, to compensate the voltage variations in the 6.6[kV]/60[Hz] power distribution system. The conventional DVR using one quasi Z-source AC-AC converter has the advantage which it can compensate the voltage variations without the need for the additional energy storage device such as a battery, but it is impossible to compensate for the 50[%] under voltage sags. To solve this problem, a DVR system using two quasi Z-source AC-AC converters with the series connection of the output terminals is proposed. By controlling the duty ratio D in the buck-boost mode, the proposed system can control the compensation voltage. For case verification of the proposed system, PSIM simulation is achieved. As a result, in case that the voltage sags-swells occur 10[%], 20[%], 60[%] in power distribution system, and, in case that the 50[%] under voltage sags-swells continuously occur, all case could compensate by the proposed system. Especially, the compensated voltage THD was examined under the condition of the 10[%]~50[%] voltage sags and the 20[${\Omega}$]~100[${\Omega}$] load changes. The compensated voltage THD was worse for the higher load resistances and more severe voltage sags. Finally, In case of the voltage swells compensation, the compensation factor has approached nearly 1 regardless of the load resistance changes, while the compensation factor of voltage sags was related to the load variations.

• Korean Journal of Community Nutrition
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• v.14 no.3
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• pp.316-326
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• 2009

The purposes of this study were to identify the significance of a nutrition teacher, to analyze the importance of competence as a nutrition teacher and to evaluate the importance and difficulty for duties of nutrition teachers. The questionnaire was distributed to 554 preliminary teachers and a total of 468 usable data were collected with 84.5% of response rate from August to October 2006. The statistical data analysis was completed by using SPSS Win (ver. 10.0) for descriptive analysis, t-test, ANOVA and ${\chi}^2-test$. The results were as follows: Preliminary nutrition teachers expected that conversion of a school dietitian into a nutrition teacher could lead to systematic and constant nutrition education and come into synergic effect by doing meal service with nutrition education. For a teacher's competence, all three paradigms were perceived as important. It was evaluated to be high for a knowledge factor in the empirical analytic paradigm, a personality factor in the practical interpretive paradigm and an attitude factor in the critical emancipatory paradigm. And 'a knowledge for nutrition and sanitation (4.59)' and 'an ability to raise a self-management capacity for right food habit and dietary life (4.59)' were showed as most important in a nutrition teacher. It appeared that both important and difficult duties of nutrition teachers were nutrition education, nutrition counseling and sanitation quality of nutrition education; the most necessary solution was to develop a reference and program for nutrition education (37.4%). In conclusion, the systematic supports of district offices of education and associated institutions as well as sustained efforts of preliminary nutrition teachers for themselves should lead to establish a successful system of nutrition teachers.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.318-320
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• 2003

This paper presents a novel single-stage high frequency resonant DC-DC converter using zero voltage switching with high input power factor. The proposed high frequency resonant converter integrates half-bridge boost rectifier as power factor corrector (PFC) and half-bridge resonant converter into a single stage. The input stage of the half-bridge boost rectifier is working in discontinuous conduction mode(DCM) with constant duty cycle and variable switching frequency. So that a high power factor is achieved naturally. Simulation results through the Pspice have demonstrated the feasibility of the Proposed DC-DC converter. This proposed converter will be able to be practically used as a power supply in various fields as induction heating applications, DC-DC converter etc.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1030-1033
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• 2002

This paper, a new simple controller operates in continuous conduction mode (CCM) for Boost power factor collection converter is introduced. The duty ratios are obtained by comparisons of a sensed signal from inductor current and a negative ramp carrier waveform in each switching period. By using the proposed controller, input voltage sensing, error amplifier in the current feedback loop, and analog multiplier／divider are not required, then, the control circuit implementation is very simple. To verify the proposed controller, the circuit simulation for Boost power factor correction converter was applied. For the results, the input current waveform was shaped to be closely sinusoidal, implying low THD.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.264-269
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• 1998

A proposed soft-switching buck-boost PWM converter has a lot of advantages, Viz., electric isolation, a high power factor, low switching losses, low EMI noise, reduction of the voltage and current stresses, etc. In a new PFC converter, the switching device is replaced by the loss-less snubber circuit to achieve the zero voltage switching (ZVS) at the maximum current. However, the charging current of the capacitor in the loss-less snubber circuit distorts the input current waveforms. To improve the input current waveform, a new duty factor control method is proposed in this paper.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.635-636
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• 2006

A pulse with modulation(PWM) that keeps a constant angle of dwell and adjust duty ratio is a good method to control a speed of SRM. And a method of one pulse control is proper a operation on range of high speed in SRM for a good energy efficiency. Because PWM method is more safety than one pulse method, conversion of those is best choice according the speed range. So, some algorithm is need for smooth conversion of the mode of control. This paper presents a factor of conversion that proper the conversion of control mode between PWM and one pulse method This factor is from estimation of torque and proper at the variable range of conversion and show the better conversion characteristic than constant factor of conversion.