• 디지털융복합연구
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• 제12권9호
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• pp.209-217
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• 2014

현대인의 피로누적과 스트레스로 인한 근육 뭉침이나 어깨 결림과 같은 고통을 호소하는 사람들을 위해 힐이, 피로회복 개념으로 안마에 대한 욕구가 계속 증가하고 있다. 이를 위해 안마의자가 개발되고 있으나 한국인의 체형에 맞지 않아 가장 효율적인 안마를 제공하지 못하고 있다. 본 논문에서는 관련연구로 안마, 어셈블러, 안마강도, 한국인의 체형을 분석하고 효율성을 극대화하기 위한 기능을 분석하였다. 또한 한국인 체형에 맞는 동작제어기 및 알고리즘을 개발하였다.

• Journal of Power Electronics
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• 제15권3호
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• pp.587-601
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• 2015

A high step-up dc-dc converter is proposed for photovoltaic power systems in this paper. The proposed converter consists of an input current doubler, a symmetrical switched-capacitor doubler and an active-clamp circuit. The input current doubler minimizes the input current ripple. The symmetrical switched-capacitor doubler is composed of two symmetrical quasi-resonant switched-capacitor circuits, which share the leakage inductance of the transformer as a resonant inductor. The rectifier diodes (switched-capacitor circuit) are turned off at the zero current switching (ZCS) condition, so that the reverse-recovery problem of the diodes is removed. In addition, the symmetrical structure results in an output voltage ripple reduction because the voltage ripples of the charge/pump capacitors cancel each other out. Meanwhile, the voltage stress of the rectifier diodes is clamped at half of the output voltage. In addition, the active-clamp circuit clamps the voltage surges of the switches and recycles the energy of the transformer leakage inductance. Furthermore, pulse-width modulation plus phase angle shift (PPAS) is employed to control the output voltage. The operation principle of the converter is analyzed and experimental results obtained from a 400W prototype are presented to validate the performance of the proposed converter.

• 임상간호연구
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• 제22권3호
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• pp.314-326
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• 2016

Purpose: The purpose of this study was to understand the experience of emotional labor of clinical nurses in medical institutes. Methods: A total of 26 nurses from 11 hospitals participated in the study. Six focus groups were organized and 4 to 5 nurses took part in each group. The compositional factors of groups included clinical experience, age, gender, work place and position. Data collection was conducted through focus group interview and it was proceeded by the time of data saturation. In this qualitative study, content analysis was conducted. Results: Five themes, 14 categories, and 33 subcategories, were emerged. The themes were 'Restrain themselves', 'Communion to the patients', 'Working environment provoking emotional tension', 'Respond to emotional events', 'Recovery of emotional energy'. Conclusion: Results indicated that surface acting of emotional labor such as, repression of personal desire and presenting the emotions that the organization ask nurse to express was related to psychosomatic symptoms, depression, burnout, poor job performance, increased mistakes, and low job satisfaction which eventually leads to nurses' turnover. In order to reduce negative influence of emotional labor, it is necessary to build positive organizational culture, to provide support from managers and co-workers. It is also important to improve work environment in order to do more deep acting since sharing emotions with patients can reduce the negative influence of emotional labor.

• 가정과삶의질연구
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• 제33권6호
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• pp.15-33
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• 2015

The present study conducted ethnography of a welfare facility for single-father families. The participants were 13 single-fathers living in a welfare facility. To explore life within the welfare facility, the qualitative research method of ethnography was used with Spradley's developmental research sequence (DRS). The major results of this study were as follows. The first theme was 'finding a way to overcome the crisis: the facility is a lifeline.' For fathers, choosing to enter a facility meant enduring a social stigma, but the decision was made with the hope of achieving successful parenting and economic independence amidst pressing difficulties. The category of living in the facility was represented by the theme 'build the family: preparing for independence through living in a welfare facility.' The fathers achieved psychological recovery through the decrease in parenting stress, improvements in their economic situation brought by living in a facility, and used this time as the foundation to gain independence and build a stable life. The event of departure from the facility was seen as 'incomplete preparation for departure' by the single fathers. The fathers with infants or younger children admitted to being anxious about leaving the facility, which involved the burden of raising the children on their own. There are practical and policy-related implications based on the results of this study.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.335-336
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• 2016

This paper introduces a bidirectional full-bridge converter with new active damp structure. The proposed active damp circuit can damp the oscillating voltage across the rectifier diodes with a smaller voltage stress of the damping capacitor and eliminate the circulating current. In addition, the proposed converter can achieve additional advantages such as nearly ZCS switching for leading-leg switches and no recovery current for rectifier-bridge by the suitable design of the damp capacitor to resonate with leakage inductor. Since the ZVS is achieved for both leading-leg and lagging-leg switches by the magnetizing current of the transformer, it can be achieved regardless of the load variation. A 3.3 kW prototype converter is implemented for vehicle-to-grid (V2G) application and the advantages of the proposed converter are verified by the experiments. The maximum efficiencies of 98.2% and 97.6% have been achieved for the buck mode and boost mode operation, respectively.

• 소성∙가공
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• 제11권2호
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• pp.171-178
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• 2002

The elastic deflections of the cold forging die influence the dimensional accuracy of forged parts. The die dimension is continuously changed during the loading, unloading, and ejecting stage. In this paper, we evaluated the elastic deflections of cold forging die during the loading, unloding and ejecting stage with experimental and FEM analysis. Uni-axial strain gages are used to measure elastic strain of die during each forging stage. Strain gages are attached un the upper surface of die. A commercial F.E.M. code, DEFORM$-2D^{TM}$ is used to predict the elastic strains of die, to be compared those by experiments. Two modelling approaches are used to define the reasonable analysis method. The first of the two modelling approaches is to regard the die as rigid body over forging cycle. And then, the die stress is analyzed by loading the die with pressure from the deformed part. The other is to regard the die as elastic body from forging cycle. The elastic strain of tool is calculated and the tool is elastically deformed at each strep. The calculated results under the elastic die assumption are well agreed wish experimental data using the strain gages.

• 대한기계학회논문집
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• 제16권10호
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• pp.1971-1978
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• 1992

본 연구에서는 원형 파이프에 원추형 디퓨져가 연결된 덕트 내의 유동장에 대 하여 Launder-Sharma의 저 레이놀즈수 k-.epsilon. 난류모델을 이용하여 수치해석을 수행하였 으며, 수치해석 방법으로는 타원형 방법을 사용하였으며, 앞으로 일반적인 단면의 곡 관이나 스크롤 내부 유동 등의 연구 수행을 감안하여 지배방정식을 일반 비직교 좌표 계로 변환하여 계산을 수행하였다.

• 대한의생명과학회지
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• 제17권4호
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• pp.321-328
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• 2011

This study divided a group of healthy adults aged 20 or older who had a health examination at J General Hospital in Gyeonggi Province into three groups according to the degrees of metabolic syndrome risk factors. They include the normal group (n=58), the pre-metabolic syndrome group (n=112) and the metabolic syndrome group (n=32). They were compared in exercise capacity and cardiac structure and function and impacts of exercise capacity on the cardiac diastolic function. All the groups took echocardiography to have their cardiac structures and functions examined and an exercise stress test to have their exercise capacity measured. The research findings were as follows: There were differences in exercise capacity, cardiac structure, and diastolic heart function among three groups. Between exercise capacity and diastolic heart function was found to be related. It turned out exercise capacity affected the cardiac diastolic functions. In conclusion, there were significant differences in exercise capacity between the normal group and the metabolic syndrome group and in the cardiac structure and function among the normal, metabolic syndrome, and pre-metabolic syndrome group. In addition, METs (metabolic equivalents) and heart rate recovery of exercise capacity turned out to affect cardiac diastolic functions.

• 한국가시화정보학회지
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• 제14권3호
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• pp.28-31
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• 2016

In this study, we investigate the wake characteristics in two cases which are laminar inflow and turbulent inflow. To solve the flow with wind turbines and its wake, we use large eddy simulation (LES) technique with actuator line method (ALM) and turbulent inflow of Turbsim. Turbulent inflow which contains the characteristic of the stable atmospheric boundary layer is used. We perform the quantitative analysis of velocity deficit and turbulence intensity in two cases. Time series of velocity deficit at the first, the second column in two cases are compared to observe the performance of wind turbine. The performance in the first column in laminar inflow is overestimated compared to that in turbulent inflow. And we observe that wake in the case with turbulent inflow drive to the span-wise direction and wake recovery in turbulent inflow is more effective. In quadrant analysis of Reynolds stress, the ejection and the sweep motion in turbulent inflow case are bigger than those in laminar inflow case.

• Tribology and Lubricants
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• 제22권5호
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• pp.243-251
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• 2006

Molecular dynamics simulations of nanoimprint lithography NIL) are performed in order to investigate effects of process parameters, such as stamp shape, imprinting temperature and adhesive energy, on nanoimprint lithography process and pattern transfer. The simulation model consists of an amorphous $SiO_{2}$ stamp with line pattern, an amorphous poly-(methylmethacrylate) (PMMA) film and an Si substrate under periodic boundary condition in horizontal direction to represent a real NIL process imprinting long line patterns. The pattern transfer behavior and its related phenomena are investigated by analyzing polymer deformation characteristics, stress distribution and imprinting force. In addition, their dependency on the process parameters are also discussed by varying stamp pattern shapes, adhesive energy between stamp and polymer film, and imprinting temperature. Simulation results indicate that triangular pattern has advantages of low imprinting force, small elastic recovery after separation, and low pattern failure. Adhesive energy between surface is found to be critical to successful pattern transfer without pattern failure. Finally, high imprinting temperature above glass transition temperature reduces the imprinting force.