• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.475-480
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• 2000

A new positioning mechanism with Parallel type actuator using piezoelectric material and with dual type actuators using voice coil motor (VCM) and piezoactuator is proposed for optical disk drive or near-field recording type drive, and high speed position and vibration control are investigated. Parallel type bimorph piezoactuator is used as a fine motion actuator with self-sensing technique, which allows a piezoelectric material to concurrently sense and actuate in a closed loop frame work, and positive position feedback control algorithm is adopted to further control residual vibration. For positioning control of VCM, PID control algorithm is adopted.

• 한국항공운항학회지
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• 제15권3호
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• pp.24-32
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• 2007

In this research, using Terfenol-D actuator composed of magnetostrictive material as shaker and controller, active vibration control theory was applied and verified by experiments. PPF(positive Position Feedback) algorithm which is effective for the control of low frequency vibration was used for the control of a structure. Responses of inputs due to various design variable used for the PPF filter were observed. To investigate the characteristics of magnetostrictive materials, actuator responses were measured for known inputs and satisfactory results were obtained to reduce the vibration level after applying the control input for the actuator.

• East Asian Economic Review
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• 제27권2호
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• pp.89-114
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• 2023

This paper empirically examines how controlling strategic goods affects productivity by focusing on Korean industries from 2015 to 2019. We hypothesize that strategic goods control positively affects productivity because it promotes international trade by making up for market failures, building up national credibility, and stabilizing market environment; in turn, international trade contributes to productivity growth. The regression results are congruent with our hypothesis. The effects of strategic goods control on productivity were positive and statistically significant in general. These positive effects were more prominent in the group of industries that include strategic goods and, thus, are technologically intensive. The results also support that international trade is a key medium for the effects of strategic goods control on productivity. Consequently, our empirical results support government policy on strategic goods control, ensuring that strategic goods control can contribute to economic growth by reducing diplomatic friction and stabilizing the global market.

• 보건행정학회지
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• 제9권1호
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• pp.201-233
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• 1999

This study was carried out to find out the factors affecting on organizational commitment of hospital employees. For the purpose, the questionnaire-based research was done with 1280 hospital employees who were working in 2 university hospitals and 4 general hospitals located in Taegu City and Kyungpook Province from November 20, 1997 to December 22, 1997. The results of the study were summarized as follows. There were significant correlations among environmental variables, psychological variables, structural variables, vertical conflict, horizontal conflict, job satisfaction, and organizational commitment. By path analysis, variables such as pay, work involvement, work definiteness, met expectations, positive affectivity, distributive justice, job security, expectations before entering a hospital had significant positive effect on job satisfaction in order of size, while, vertical conflict, job opportunity, and horizontal conflict had significant positive effect on job satisfaction in order of size, while, vertical conflict, job opportunity, and horizontal conflict had signifecant negative effect in order of size. Variables such as job satisfaction, job security, work involvement, pay, vertical conflict, met expectations, distributive justice, positive affectivity, work unit control, job autonomy, and job routinization had significant positive direct effect on organizational commitment in order of size, while, job opportunity, job hazards and resource inadequacy had significant negative direct effects in order of size. It was found that the following variables, listed in order of size, had significant total effects on organizational commitment : job satisfaction, job security, job opportunity, work involvement, pay, met expectations, distributive justice, positive affectivity, job hazards, and work unit control. In considering abovc findings, it is recommended that programs for job satisfaction promotion, job security, decrease of intent to leave, work involvement promotion, adequate pay, met expectations, distributive justice, positive affectivity promotion, job hazards decrease, and work unit control grant should be implemented to increase organizational commitment.

• 복식문화연구
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• 제21권4호
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• pp.478-493
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• 2013

The purpose of this study is to examine the online WOM effect of blog review depending on brand awareness and message direction. The theory of planned behavior was applied to understand online WOM acceptance. A survey was conducted targeting female in 20s and 30s and 312 questionnaires were used for analysis. Frequency analysis, reliability analysis, t-test, and regression analysis were conducted using SPSS ver. 18.0. The results are as follows. First, purchase intention and online re-WOM intention are higher when brand awareness is higher. Second, subjective norm, perceived behavioral control, WOM acceptance intention, purchase intention and off-line re-WOM intention show higher values when negative information is afforded. Third, in type 1 (high brand awareness/positive message) and type 3 (low brand awareness/positive message), attitude, subjective norm and perceived behavioral control have a positive effect on WOM acceptance intention. In type 2 (high brand awareness/negative message), subjective norm and attitude have a positive effect on WOM acceptance intention. In type 4 (low brand awareness/negative message), subjective norm and perceived behavioral control have a positive effect on WOM acceptance intention. Forth, in type 1 and type 3, WOM acceptance intention has a positive effect on purchase intention, offline re-WOM intention and online re-WOM intention. In type 2 and type 4, WOM acceptance intention has a negative effect on purchase intention, and a positive effect on offline re-WOM intention. The results show that blog review has ripple effect on consumer behavior by affecting purchase intention and offline re-WOM intention.

• 대한간호학회지
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• 제37권4호
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• pp.510-518
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• 2007

Purpose: This study examined the effects of an insight-oriented nursing program on schizophrenic patients' insight, positive and negative syndromes, and depression. Method: A non-equivalent control group non-synchronized design was utilized. For this research, a total of 34 subjects were selected at a psychiatric hospital in Daegu during the period ranging from Oct. 1st, 2005 to Feb. 11th, 2006 (experimental group=17, control group=17). Result: After the treatment, between the experimental and control groups, there wasa significant difference in the level of SUMD(t=-4.52, p=.000) and positive syndrome(t=6.97, p=.013), but no significant difference in the negative syndrome(t=-1.81, p=.079) and depression(t=2.23, p=.145). Conclusion: The results of this study show that the insight-oriented nursing program works well for schizophrenic patients. Therefore, it is recommended that this program should be used in clinical practice as an effective nursing intervention for schizophrenic patients.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.524-526
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• 2011

This paper focuses on study on PWM converter control under unbalanced network condition. Voltage unbalance in a three-phase system causes the performance deterioration by producing 120 Hz voltage ripples in the DC link and 120 Hz ripple in reactive power. To eliminate the ripples, both positive and negative sequence currents should be controlled simultaneously. In this paper four PI controllers on synchronous reference frame is implemented to control D and Q currents in both positive and negative sequence. Positive and negative sequence signal extraction is done using delay signal cancellation method. Simulation results show satisfactory performance in suppressing 120 Hz ripples.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권4호
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• pp.203-209
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• 2002

This paper presents a new control scheme for a DVR(Dynamic Voltage Restorer) system consisting of series voltage source PWM converters. To control negative sequence component of source voltage the detection of negative sequence is necessary. Generally, filtering process is used tn do that. Through this filtering process has some problems. This paper suggests a new method of separating positive and negative sequences. This control system is designed using differential controllers and digital filters, and positive sequence and negative sequences are controlled respectively. The performance of the presented controller and scheme are confirmed through simulation and actual experiment by 2.5kVA prototype DVR.

• 제어로봇시스템학회논문지
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• 제5권7호
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• pp.787-793
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• 1999

A self-sensing magnetic suspension system utilizing a LC resonant circuit is proposed by using the characteristic that the inductance of the magnetic system is varied with respect to the air gap displacement. An external capacitor is added into the electric system to make the levitation system be statically stable system, which much relieves the control effort required to stabilize the magnetic suspension system of haying an intrinsic unstable nature. For the realization of the self- sensing magnetically levitated system, an amplitude modulation / demodulation method is used with a positive position feedback controller Experimental results are presented to validate the proposed method.

• 산업기술연구
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• 제19권
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• pp.217-226
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• 1999

A single phase to three phase power converter with cost effective and simple structure is proposed. The converter consists of rectifier and inverter. The rectifier is composed of a half wave rectifier, a dc link capacitor, and a current limiting inductor, and the inverter is of only two switches with PWM control. For negative sequence operation the inverter output voltage leads the line input by $60^{\circ}$, and for positive sequence operation the inverter output voltage leads by $60^{\circ}$. We can see that positive sequence operation shows higher output voltage, slight harmonic distortion(2%), and better performances such as high efficiency and high power factor. A mathematical model for system analysis is provided, and specifications for selection and control scheme both for start-up and for steady state are analyzed. comparison and operational limits of positive and negative sequence operation are performed, and simulations and experiments are executed to verify the proposed.