• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.709-711
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• 2006

According as optical storage becomes high-density, numerical aperture increases. Therefore, the shift characteristic of moving parts in an actuator for optical pickup becomes a critical design factor because of decrease in the tilt margin. The tilt angle is maximized when the position of moving parts is in a diagonal direction within a moving range. This is determined by design of structure and magnetic circuit of an actuator. Previous analysis method only predicts linear characteristics of moving parts. However, the result of shift characteristics of the moving parts considering structural and magnetic circuit's nonlinearity following the every position simultaneously shows us more realistic result. Therefore, we present analysis method considering nonlinearity of moving parts' position through FEM package using coupled-field analysis. Then, we will suggest hereafter a design guide by comparing the above results with experimental ones.

• Journal of Korean Academy of Nursing Administration
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• 제21권5호
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• pp.519-529
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• 2015

Purpose: This study was performed to identify perceptions on fixed night shift system and turnover intention of general hospital nurses and to explore a desirable application plan for a fixed night shift system. Methods: This study was a cross-sectional survey. Participants were 300 nurses working at one general hospital in GyeongGi-Do, Korea. Data were collected from November 3 to 7, 2014, with a structured questionnaires and analyzed using SPSS/PC ver 20.0 programs. Results: Of the participants 73.5% had thought about turnover because of night shifts and the preconditions for desirable fixed night shift system were a payment plan differentiated according to work conditions and an adequate number of nursing staff. Economic and administrative supports like 'raising extra-pay for night shift' and 'increasing the number of paid holidays' were very important for a desirable fixed night shift system. Conclusion: The results indicate that the most important factor for a desirable fixed night shift system to decrease nurses' turnover intention is economic and administrative support according to the needs of the nurses. So nursing managers need to find a desirable fixed night shift system considering nurses' demographic characteristics and organizational characteristics.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제38권5호
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• pp.456-466
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• 2010

Typical combustion instability such as DC-Shift found in the hybrid rocket motor is characterized by non-linearity. DC-Shift can occur in two different realizations. One is so-called a positive shift of measured DC voltage where the pressure increase suddenly. The other is a negative shift where the pressure drops abruptly. In the present work, specifically the negative DC-Shift was investigated to analyze the effect of oxidizer flow condition and the resonance between fundamental frequency and other ones, such as Helmholtz frequency, and acoustic frequency. Results show a peak frequency of several hundreds HZ shifts as combustion proceeds. A negative DC-shift was found as the result of phase cancellation between two dominant frequency, combustion frequency and flow related frequency. Still is it required to study further to identify the change of dominance of frequency during the combustion.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• 제20권5호
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• pp.639-645
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• 2011

Wheel-loader is a construction vehicle for uploading soil or sand into truck and transportation of materials, which requires large driving power and high rotational speed. To improve the working efficiency, the operator has to shift gears and control levers for bucket & boom simultaneously. Therefore, the automatic transmission has been introduced to enhance operator's convenience and enable effective operation. To develop the automatic transmission for the wheel-loader, technologies such as gears and a clutch-pack design and shift algorithm are required for improvement of shift quality. In this paper, the shift algorithm for the wheel-loader was developed and its shift pattern was analyzed. As the shift control is affected by the pressure profile for the clutch control, the shift quality depending on the pressure profile has been evaluated using experiment and simulation model analysis.

• Journal of muscle and joint health
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• 제21권2호
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• pp.135-144
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• 2014

Purpose: The purpose of this study was to analyze and clarify the concept of shift work maladaptation syndrome and to facilitate development of interventions for the shift work adaptation. Methods: This study used Walker and Avant's concept analysis process. Results: Shift work maladaptation syndrome can be defined as the following attributes: 1) destruction of the circadian rhythm, 2) existence of a threshold, 3) individual characteristics (year of career, type of personality, and type of coping) 4) somatization, and 5) negative emotional conditions. The antecedents of shift work maladaptation syndrome consist of counterclockwise shift work, irregular shift cycle, night work which is breaking circadian rhythm, and lifestyle changing. The consequences as a result of shift work maladaptation syndrome are deterioration of health (gastrointestinal, neuro-psychic, cardiovascular function), reduction of social relationships, and turnover or resign. Conclusion: The results of this study can be useful as the foundation of shift work adaptation implementation.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제56권1호
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• pp.156-160
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• 2007

Surface plasmon resonance(SPR) has been widely studied for biological and chemical sensing applications. The present study conducts numerical simulation for the single and bimetallic layer SPR configurations by using the multiple beam interference matrix(MBIM) method to investigate the influence of wave interference and complex refractive indices of materials on optical characteristics such as reflectance and optical phase shift which are used for sensing. First, calculated reflectances are compared with experimental data for validation. In addition, in the single film structures this study finds out the appropriate film thicknesses with minimum reflectance for cases of gold film and silver film. For a bimetallic silver-gold film structure, in particular, the bimetallic film thicknesses that has the minimum reflectance are found 36 nm for silver and 5 nm for gold. From the results, the use of phase shift would be useful compared to reflectance in determining the SPR configuration because the phase shift becomes more sensitive than reflectance.

• Proceedings of the KIEE Conference
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1168-1170
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• 2000

A half bridge time sharing type high frequency resonant inverter to give VVVF function in the inverter used as power source of induction heating at high frequency is presented in this paper, this paper also realize the output control of independence irrespective of the switching frequency using Phase-Shift. The analysis of the proposed circuit is generally described by using the normalized parameters. Also, the principle of basic operation and the its characteristics are estimated by the parameters, such as switching frequency, the variation of phase angle(${\varphi}$) of Phase-Shift. It is certain that the proposed circuit will be used and expanded in the high frequency power supplies like induction heating systems.

• The Transactions of the Korean Institute of Electrical Engineers A
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• 제49권10호
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• pp.486-493
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• 2000

This paper presents an application to a multimachine power system of power system stabilizer using revised pole shift adaptive algorithm. Controller parameters are determined by using adaptive control theory in order to maintain optimal operation of generator under the various operating conditions. To determine the optimal parameters of controller and overcome the problem of pole placement algorithm, this paper presents pole shift algorithm revised pole shift factor. Also, the difference between the speed deviation with weighted factor and voltage deviation is used as the input signal of adaptive controller, which provides good damping characteristics. The results tested on a multimachine power system verify that the proposed controller has better dynamic and transient performance than conventional controller.

• Transactions of the Korean Society of Automotive Engineers
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• 제8권1호
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• pp.63-71
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• 2000

A shift control algorithm of a newly developed two-speed gear shift system is proposed for electric vehicle applications. The algorithm is formulated according to the motor torque map and optimized to obtain the adequate propulsion characteristics for vehicle. Two speed gear system with shift control algorithm has proved greater efficiencies in terms of energy economy with its simplified hardware and software structures. The gear shifting is designed to be carried out by an actuator and the control signal from a vehicle control unit equipped with $\mu$-processor. The results of performances and efficiency of the algorithm by simulation and vehicle test are described.

• Transactions of The Korea Fluid Power Systems Society
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• 제6권3호
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• pp.10-15
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• 2009

The major system of an agricultural power-shift tractor is the transmission, using power-shift. Because the transmission performance depends on the hydraulic control system, the most important aspect of the optimization is the design of the hydraulic control system. This study was conducted to improve a pressure modulation characteristics of the power-shift transmission hydraulic system. It has been tried to replace an existing pressure modulation method with a digital control by using HSSV(High Speed Solenoid Valve). The performance of the PWM control system in power-shift hydraulic transmission has been evaluated by means of experiment.