• Tunnel and Underground Space
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• v.16 no.1 s.60
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• pp.85-94
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• 2006

In this study, scaled model tests were carried out to decide the optimal critical velocity, to prevent back layering in the case of fire in a long traffic tunnel. Realistic estimates were made for the time required for people to escape ken the tunnel and far the time required by the ventilation operator to increase the system speed to full capacity. The analysis, predicts that the emergency ventilation will start about 240 seconds after the tunnel fire. It was also found that prevention of back layering would occur within 4 minutes after fan operation. To find out optimal critical velocity, a 1/50 scaled model tunnel(diameter : 0.2 m and length : 20 m) based on the Froude similarity technique was constructed. Changing $\beta$ values in the Tetzner's equation, smoke propagation was observed. From the experiment, it was concluded that using a $\beta$ value of 0.5 to prevent back layering successfully allowed time for safe evacuation.

• Korean Security Journal
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• no.36
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• pp.469-492
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• 2013

While the average age of population increases, so as the number elderly workers employed in the private security in Korea. However, not many studies have examined the issues related to elderly security guards so far, especially regarding the experience of workplace violence victimization even though they are quite vulnerable. The current study surveyed elderly private security guards across the nation in an attempt to ask about their workplace violence victimization experience, including both physical and verbal ones. The researchers investigated if victimization experiences affect the elderly security guards' perception of occupational stress. The result indicated that the respondents experienced verbal violence more than physical violence, and perpetrators were usually customers, not their supervisor or coworkers. In addition, those who experienced verbal violence in the workplace, perceived a higher level of occupational stress. The experience of physical violence did not make a significant impact. Policies are discussed in order to decrease workplace violence towards elderly security guards.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1822-1826
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• 2009

최근 국내 하천복원사업의 방향(패러다임)이 구하도를 포함한 홍수터의 중요성을 인식하게 됨에따라 과거 하천사업 시 발생되었던 폐천구역을 가능한 한 하천구역에 편입하여 보존하려는 노력이 시도되고 있다. 본 연구는 하천복원사업의 일환으로 함평천 구하도 복원을 함으로써 발생할 수 있는 흐름특성변화 및 하상변화를 파악하기 위한 목적으로 수리모형실험과 수치모의를 수행하였다. 실험대상구간은 함평천 중류 구하도 복원구간(1.34 km)이며, 수리모형은 Froude 상사법칙에 따라 수평축척 1/50, 연직축척 1/25의 모형으로 제작하였다. 실험조건으로는 재현기간 50년, 100년의 홍수량과 강턱유량 두 케이스$(100\;m^3/s$, $120\;m^3/s)$를 적용하였고, 구하도 복원수로의 흐름특성은 고정상 조건에 대해 분석하였다. 구하도 복원전/후의 홍수위 비교를 통해 구하도 복원후의 하도에서는 단면확대로 인한 통수능 증가로 홍수위 저감효과를 확인 할 수 있었다. 구하도 복원후의 유속변화는 통수능의 증가로 복원전에 비해 저감되었다. 기존하도와 복원하도간의 유속차가 다소 크게 나타났는데 이는 복원하도의 단면형상과 와류발생으로 인해 나타난 것으로 판단된다. 복원하도내의 유황은 일부구간에서 흐름정체현상과 역류현상이 발생되는데 이 구간에는 퇴적현상이 예측된다. 수리모형실험의 유사퇴적경향과 FESWMS 모형의 하상전단력을 비교한 결과는 유사하게 나타났으며, 복원하도의 넓은 둔치지역에 넓은 퇴적층이 형성되어 차후 환경구조물 등을 이용한 흐름제어 및 유지관리대책에 의한 문제해결이필요할 것으로 판단된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3374-3383
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• 2011

In this study, numerical analyses for slamming impact phenomena have been carried out using a 2-dimensional wedge shaped structure having finite deadrise angles. Fluid is assumed incompressible and entry speed of the structure is kept constant. Geo-reconstruct(or PLIC-VOF) scheme is used for the tracking of the deforming free surface. Numerical analyses are carried out for the deadrise angles of $10^{\circ}$, $20^{\circ}$ and $30^{\circ}$. For each deadrise angle, variations are made for the grid size on the wedge bottom and for the entry speed. The magnitude and the location of impact pressure and the total drag force, which is the summation of pressure distributed at the bottom of the structure, are analyzed. Results of the analyses are compared with the results of the Dobrovol'skaya similarity solutions, the asymptotic solution based on the Wagner method and the solution of Boundary Element Method(BEM).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.868-874
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• 2007

Noises from the helicopter rotor model are calculated numerically at various pitch angles. The aerodynamic data are calculated by using prescribed wake model and unsteady panel method. The distribution of aerodynamic loads on the blade surface are obtained from $0^{\circ}$ to $9^{\circ}$ pitch angles with equiangular increments of $1.5^{\circ}$. Although thickness noise is not related to the change of pitch angles, loading noise level increases about 3~4dBA every $1.5^{\circ}$ increment of pitch angle. The additive noise level shows sufficient value to perceive the loudness. From the result of directivity pattern the sound level at the lower region of the blade disc plane is higher than that of the upper region.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6146-6154
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• 2013

This study examined the status on job satisfaction and job performance of Advanced Practice Nurses (APNs) in Korea. The data was obtained from the 2009 APNs' job satisfaction survey of 452 nurses who received the certificate of APN between 2005 and 2008 conducted by the Korean Accreditation Board of Nursing Education. ANOVA and t-test analyses using SPSS version 14.0 were performed. The average job satisfaction level of the APNs was 2.94 out of 5.00. APNs who were performing jobs as a certified APN had a higher level of job satisfaction (t=.23, p<.001), higher wages (t=2.23, p<.05), promotion in rank (t=2.56, p<.05), more professional job performance (t=10.52, p<.001), greatest trust in their bosses and coworkers (t=5.31, p<.001), and higher confidence in their job performance (t=5.07, p<.001) than those who were not. The government and the nursing community need to provide the APNs' with the appropriate supply and demand polices, as well as a proper incentive system and job improvement.

• The Journal of the Korea Contents Association
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• v.9 no.2
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• pp.279-288
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• 2009

The purposes of this study were to understand the differences of general characteristics, to compare understanding level of the organization cultures, and to develop more good management methods between outsourcing workers and regular workers in hospitals. Major results of this study were as follows: First, regular workers had higher level than outsourcing workers in major understanding on job satisfaction and organization cultures(pride of their jobs, recognition level of job performance ability, satisfaction on ordering method. etc.). Second, the results showed that the level of job performances related with effective management of the factors in job satisfaction and involvement. Third, through multiple regression analysis to understand factors on job satisfaction and involvement, we understood that regular workers were effected by vision performance of hospital and their value view-point, and outsourcing workers were influenced by recognition levels and education levels of hospital vision, Therefore, to maximize level of job satisfaction and involvement. we have interest in development of education program for outsourcing workers, and selection of adequate persons in hospital culture.

• Journal of Advanced Navigation Technology
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• v.13 no.1
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• pp.1-10
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• 2009

In this study, what effects corporate culture of airlines' flight attendants has on job satisfaction was analyzed and the following results were derived. First, it showed that flight attendants of airlines feel job satisfaction with the ability of handling works by themselves before supervisors order something, with the faith of supervisors that subordinates will be able to work well, and with being able to talk about difficulties of the company open-minded. Second, flight attendants inairlines showed different levels of recognition about corporate culture based on age, married or not, position and how long they have worked in the company. Especially, it showed a big difference by their positions. Third, looking into the effect demographical characters have on job satisfaction, it indicated that the higher the positions were, the higher job satisfaction was, and especially, compared that job satisfaction of flight attendants having 4-7 years' careers is low, that of the flight attendantsmore than 8 years is high.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.231-235
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• 2009

The mainly objectives of this study was a combustion dynamics and instability characteristics in a model dump type combustor which is scale down of GE 7FA+e DLN 2.6 gas turbine combustor with running at Seo-Inchon combined cycle power plant. Model gas turbine injector has 2-stage swirl vane and it's reduced 1/3 size of the original one. The shape of plenum and combustor were designed for similar acoustic characteristics. As the result, this research have been shows the peak frequency of model combustor was changed quarter-wave mode to Helmholtz resonator mode in plenum and longitudinal mode in dump combustor at unstable flame conditions caused by the different of combustor temperature and fuel-air mixture distributions.

• The Korean Journal of Applied Statistics
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• v.21 no.3
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• pp.469-484
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• 2008

This study was intended to examine various work and environmental variables explaining newcomers' turnover intentions. Data were collected from 901 newcomers using online survey. Results of multiple regression analyses showed that individual-job fit, reward dissatisfaction, fringe benefit dissatisfaction, vision in organization, participation in decision making, realistic job preview, leader dissatisfaction, co-worker relationship and work environment explained significant variances of turnover intentions. Data were classified into full-time and part time employees based on employment type and into a large and a small-medium company based on company size. There were small differences in significant variables explaining turnover intentions based on company size as well as employment type. Finally implications and future research were discussed.