• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1112-1113
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• 2007

능동형 자기베어링과 보(Beam)와 피봇으로 구성되는 시소 (SISO)는 제어적 관점에서 보면 많은 유사성이 있다. 본 논문에서는 Carl R. Knospe 등이 제안한 보와 피봇을 이용한 1자유도 자기베어링 시뮬레이터를 실제 제작하여, 비레 미분 적분 제어 알고리즘을 적용한 디지털 제어기와, 큰 힘을 발생시키기 위해서는 필연적인 전자석 코일의 큰 인덕턴스에 의해 제한되는 Bandwidth(BW)를 보상하기 위해 앞섬 보상기를 가지는 전류제어기를 구현하였다. 복잡한 자기베어링 시스템을 기구적으로 간단한 보와 피봇 시스템으로 상사시킴으로써, 자기베어링 제어 알고리즘 개발 및 파라미터 튜닝의 목적을 달성할 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.1
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• pp.150-155
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• 1994

An Approximate solution for plane two-dimensional incompressible laminar jet issuing from a finite opening with arbitrary initial profile into the same ambient fluid is proposed. For an arbitrary initial velocity profile, the problem is generated from the well known similarity solution for the jet of infinitesimal opening and provides good approximations in the region where the similarity solution cannot be used as an approximation. The asymptotic behavior of this solution is investigated and it is shown that, as goes downstream, the present solution approachs the similarity solution.

• Korea Journal of Hospital Management
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• v.26 no.4
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• pp.38-50
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• 2021

Purpose: The purpose of this study was to identify the relation among affect climate, organizational commitment and organizational performance. Methodology: The survey was conducted through online questionnaires from April 28 to May 1, 2020 for workers in medical institutions. Multiple regression analysis and mediating effects test were performed to identify the influence relationship. Findings: The results, based on a sample of 344 workers in medical institutions, indicate that Positive display climate, Positive experiential climate and Authentic experiential climate are positively related to both organizational commitment and organizational performance. We also found that the lemotional sharing has a partial mediation effect in the relationship that positive display climate, positive experiential climate, and authentic experiential climate affect affective organizational commitment. Practical Implications: Emotional sharing is encouraged for hospital's workers, and the authentic experiential climate contributes to improving work efficiency as well as organizational performance.

• Korean Journal of Social Issues
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• v.18 no.1
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• pp.57-81
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• 2017

이 연구는 인천광역시 소재 사회복지시설에 근무하는 사회복지사 274명을 대상으로 2015년 5월 및 7월에 실시한 설문조사 결과 중 사회복지사들이 겪은 인권침해와 불이익 경험 여부 및 영향요인을 분석하였다. 이를 위하여 이 연구는 인권침해는 상사나 동료 및 클라이언트의 폭언, 폭력, 성희롱의 경험으로, 불이익은 임금과 수당, 복리후생, 기관운영에서의 차별로 구분하였다. 로지스틱 회귀분석 결과, 이 연구는 사회복지사가 여성일수록, 연령이 낮을수록, 기혼자일수록, 고용형태가 비정규직일수록, 근로시간은 길수록 인권침해와 불이익을 경험하게 되는 확률이 상대적으로 높으며, 대학원 이상의 학력 소지 사회복지사의 경우 불이익 경험 보다 인권침해 경험을 받을 가능성이 높은 것으로 확인하였다. 또한, 이 연구는 사회복지사들은 인권침해 경험에도 불구하고 직장 내에서 이를 문제로 제기한 경우는 10.3%에 불과한 것도 확인하였다. 전국 및 기초지자체 차원에서 사회복지사의 근로환경과 인권침해에 관한 조사연구가 있는 상황에서, 처음으로 광역지자체차원에서 이를 분석한 이 연구는 사회복지사의 인권침해와 불이익의 예방과 피해구제를 위한 적극적 조치가 필요하다는 의견도 제시하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.331-345
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• 2018

Sports participation can contribute to organization members' work-life balance and work motivation in order to increase performance. Based on the achievement motivation theory, this study tested the effect of sports participation on leaders' effectiveness and employees' performance. Data was collected from 213 leaders and subordinates in the South Korean army. Results indicated that leader effectiveness mediated the positive relationship between sports participation of leaders and subordinates' outcomes, such as task performance and OCB. We also found that sports participation of subordinates moderated the positive relationship between leader effectiveness and subordinates outcomes (i.e., task performance and OCB). These findings further suggest that sports participation plays an important role for leaders and subordinates to increase leader effectiveness and in/extra-role behaviors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.569-578
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• 2017

The purpose of this study is to investigate the effects of informational diversity-sensitive orientation on employee attitudes, focusing on the moderating effects of communication. Recently, diversity within organizations has intensified and the importance of diversity management within organizations is increasing. Diversity studies have focused on the variance of objective diversity characteristics, and have provided mixed results. In order to overcome limitations in the research, this study focuses on members' perception of diversity. To this end, the variable of informational diversity-sensitive orientation(IDSO) was used. Sample data is derived from 301 surveys of employees in firms located in South Korea. Results show that informational diversity-sensitive orientation(IDSO) had a positive effect on job satisfaction and organizational commitment. Regarding the moderating effect of communication, a positive moderating effect was exhibited only in co-worker communication, and differential influence derived from communication type. Based on the analysis results, we discuss research implications and directions for future research.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.259-268
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• 2012

This study measured the natural-convection heat transfer of two vertically staggered cylinders with varying vertical pitch-to-diameter ($P_v$/D) and horizontal pitch-to-diameter ($P_h$/D) ratios. The measured heat-transfer rates for the lower cylinder agreed well with the existing heat-transfer correlations for a single cylinder. At the smallest $P_v$/D, the rising plume from the lower cylinder provides the upper cylinder with a preheated flow, and the heat-transfer rates of the upper cylinder decrease, but increase very sensitively with $P_h$/D. However, at the largest $P_v$/D, the velocity effect dominates, and the heat-transfer rates of the upper cylinder are larger than that of a single cylinder, and decrease less sensitively with $P_h$/D. Even if $P_h$/D is increased, the heat-transfer rate of the upper cylinder is higher than that of the lower cylinder because of the chimney and side flow effects. This work expanded the flow ranges to turbulent flows. The cupric acid-copper sulfate ($H_2SO_4-CuSO_4$) electroplating system was adopted for the measurements of the mass-transfer rates instead of the heat-transfer experiments based on the analogy concept. The measurements were made by varying $P_v$/D (1.02-5) and $P_h$/D (0-2) in both laminar and turbulent flows. The Rayleigh number ranged from $1.5{\times}10^8$ to $2.5{\times}10^{10}$, and the Prandtl number was 2,014.

• Journal of Energy Engineering
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• v.21 no.1
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• pp.18-25
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• 2012

This work investigated the influence of the chimney dimensions(exit and entrance length, and diameter) on the heat transfer of a vertical cylinder in a duct. The measured mass transfer rates for the natural convection of vertical cylinder in a duct were presented for Prandlt number 2,094, Rayleigh number in the range of $4.55{\times}10^9$, $5.79{\times}10^{10}$, and $1.69{\times}10^{11}$. Experiments were performed using a copper sulfate electroplating system to simulate heat transfer based upon the analogy concept. The diameter of the duct was varied from 0.06 m to 0.14 m, and the heights from 0.30 m to 1.10 m. Nusselt numbers measured at open channel condition agreed well with the existing laminar heat transfer correlations for vertical plate developed by Le Fevre. The increase of the exit length enhanced the heat transfer up to a certain duct height but further increase does not affects the heat transfer. The heat transfer decreased with increasing the entrance length up to a certain duct height and was constant at further increase. The Nusselt number decreased with increasing the diameter of duct, until Nusselt number becomes similar to that at open channel beyond a certain diameter.

• Journal of Energy Engineering
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• v.20 no.3
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• pp.242-251
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• 2011

The effects of top and bottom lids on the natural convection heat transfer phenomena inside vertical cylinders were investigated experimentally for $Ra_{Lw}$ from $9.26{\times}10^9$ to $7.74{\times}10^{12}$. Using the concept of analogy between heat and mass transfer, a cupric acid-copper sulfate electroplating system was employed as mass transfer experiments replacing heat transfer experiments. The natural convection heat transfer of both-open cylinders in laminar and turbulent flows was in good agreement with the existing heat transfer correlations developed for vertical plates. The effects of top and bottom lids on the heat transfer rates were very similar to the studies of Krysa et al. and Sedahmed et al. and Chung et al. With the copper lids, the bottom-closed cavity showed the highest heat transfer rates and then followed both-closed, top-closed, both-open ones in both laminar and turbulent flows. However with the acryl lids, the similar trends were observed except that the heat transfer rates for both-open were higher than top-closed one. The use of the copper lids increased the heat transfer rates compared to the acryl lids due to the hydrodynamic interaction of the flows developed for the different heated faces. This study extended the ranges of flow conditions of the existing literatures and proposed the empirical correlations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.2169-2177
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• 2010

The effects of job related factors on psychosocial health status were examined by taking job stress into account. The self-administered questionnaires were performed, during the period between Oct. 1st, 2009 and Nov. 30th, 2009, to 805 individuals in the service of general administration located in Daejeon City. Causal relationships between job related factors, job stress, and, psychosocial health status were examined by structural equation model. The main finding as follows: For correlations of such indices of psychosocial health status as PWI and MFS with various studied items, all of these two indices were found to be in a negative correlation with the job position, job career, satisfaction in job life, autonomy of job, supervisors support and coworkers support, whereas in positive correlation with the experience of sick absence per year and job demand. With the analysis of structural equation model, the degree of job stress factors was more influential on the level of psychosocial health status than job related factors in such a manner as that the greater the job stress, while the lower the job related factors, the higher the psychosocial health status(PWI and MFS). Moreover, it was found to have the inter-relational effects that the greater the job related factors, the lower the job stress factors. Thus the effective strategy for stress and fatigue symptoms reduction among governmental employees requires additional programs focusing on innovated job specifications.