• 한국화재소방학회논문지
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• 제24권5호
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• pp.87-93
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• 2010

화재 시 피난 및 소화활동에 큰 지장을 초래하고, 인명안전에 가장 큰 위협이 되고 있는 연기의 제어를 위한 제연시스템의 중요성이 강조되고 있다. 국내에서는 고층 건축물의 화재 시 피난계단으로의 연기 침투를 방지하여 안전한 피난경로를 확보하기 위하여 화재안전기준 NFSC501A의 "특별피난계단의 계단실 및 부속실 제연설비의 화재안전기준"이 제시되어 있으며, 이를 위하여 국내에서 일반적으로 사용하고 있는 방법이 제연용 송풍기와 수직풍도를 이용하여 거실과 계단실 사이에 위치하는 부속실에 외기를 급기함으로써 부속실을 단독으로 제연하는 급기가압 제연시스템이다. 본 연구에서는 20층 규모의 모델 건축물을 대상으로 NFSC501A 기준과 엔지니어링 설계방안을 바탕으로 급기가압제연시스템을 설계하였으며, 네트워크 모델의 수치해석기법을 사용하여 급기가압 제연시스템에 의해 형성되는 건축물 내 압력장을 분석 하였다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 추계학술발표회논문집(1)
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• pp.97-102
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• 1996

A methodology for estimating the number of failed fuel rods bused on the primary coolant activity in operating PWRs has been developed. This method deals with both the diffusion and the kinetic models. In case of small or medium cladding failures, the diffusion model which can consider different sizes of failure is used, whereas for large cladding failures the kinetic model is used. From the kinetic model, the release-to-birth rate ratio (R/B) is represented as a linear function of the number of failed fuel rods. This has been done by expressing the escape rate coefficient in terms of the slope of log(R/B) versus $log\;{\lambda}$. The present method has been applied to the cases of 26 cycles of several nuclear power plants for which ultrasonic testings were performed. The results show that the present method gives better predictions than the existing computer codes such as IODYNE and CADE.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.163-167
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• 2008

In this study, the 1/35 reduced-scale model experiment were conducted to investigate designed ventilation effect on the smoke movement at rescue station fire in railway tunnel. A model tunnel with 2 mm thick, 10 m long, 0.19 m high and 0.26 m was made by using Froude number scaling law. The cross-passages installing escape door at the center were connected between incident tunnel and rescue tunnel. The n-heptane pool fires with heat release rate 698.97W were used as fire source. The fire source was located at the center and portal of incident tunnel as worst case. A operating ventilation system extracted smoke amount of 0.015 cms(cubic meters per second). The smoke temperature and CO gas concentration in cross-passage were measured to verify designed ventilation system. The result showed that, at center fire case without ventilation, smoke did not propagate to rescues station. In portal fire case, smoke spreaded to rescues station without ventilation. But smoke did not propagated to rescues station with designed ventilation.

• Tribology and Lubricants
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• 제36권6호
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• pp.359-364
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• 2020

Numerical investigation of the groove trap effect with variation in the groove-edge radius of curvature is presented here. The trap effect is evaluated in a two-dimensional sliding bearing using computational fluid dynamics (CFD). This simulation is based on the discrete phase model (DPM) and standard k - ε turbulence model using commercial CFD software, FLUENT. The numerical results are evaluated by comparisons with streamlines and particle trajectories in the grooves. Grooves are applied to various lubrication systems to improve their lubrication characteristics, such as load carrying capacity increment, leakage reduction, frictional loss reduction, and preventing three-body abrasive wear due to trapping effect. This study investigates the grove trapping effect for various groove-edge radius of curvature values and Reynolds numbers. The particle is assumed to be made of steel, with a circular shape, and is injected as a single particle in various positions. One-way coupling is used in the DPM model because the single particle injection condition is applied. Further, the "reflect" condition is applied to the wall boundary and "escape" condition is used for the "pressure inlet" and "pressure outlet" boundaries. From the numerical results, the groove edge radius is found to influence the groove trap effect. Moreover, the groove trap effect is more effective when applying the groove edge radius.

• Journal of Astronomy and Space Sciences
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• 제30권3호
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• pp.133-140
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• 2013

Most of high energy cosmic rays (CRs) are thought to be produced by diffusive shock acceleration (DSA) at supernova remnants (SNRs) within the Galaxy. Fortunately, nonthermal emissions from CR protons and electrons can provide direct observational evidence for such a model and place strong constraints on the complex nonlinear plasma processes in DSA theory. In this study we calculate the energy spectra of CR protons and electrons in Type Ia SNRs, using time-dependent DSA simulations that incorporate phenomenological models for some wave-particle interactions. We demonstrate that the time-dependent evolution of the self-amplified magnetic fields, Alfv$\acute{e}$nic drift, and escape of the highest energy particles affect the energy spectra of accelerated protons and electrons, and so resulting nonthermal radiation spectrum. Especially, the spectral cutoffs in X-ray and ${\gamma}$-ray emission spectra are regulated by the evolution of the highest energy particles, which are injected at the early phase of SNRs. Thus detailed understandings of nonlinear wave-particle interactions and time-dependent DSA simulations of SNRs are crucial in testing the SNR hypothesis for the origin of Galactic cosmic rays.

• 천문학회지
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• 제27권1호
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• pp.45-53
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• 1994

We present the calculation of X -ray spectra produced through Compton scattering of soft X-rays by hot electrons in the spherical shell geometry, using fully relativistic Monte Carlo simulation. With this model, we show that the power-law component, which has been observed in the low luminosity state of low-mass X-ray binaries (LMXBs), is explained physically. From a spectral. analysis, we find that spectral hardness is mainly due to the relative contribution of scattered component. In addition, we see that Wi en spectral features appear when the plasma is optically thick, especially in the high energy range, $E{\gtrsim}100keV$. We suggest that after a number of scattering the escape probability approaches an asymptotic form depending on the geometry of the scattering medium rather than on the initial photon spectrum.

• 항공우주기술
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• 제7권2호
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• pp.53-57
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• 2008

지식경제부 과제인 중형위성급 제어모멘트자이로 성능검증모델 개발 사업을 수행하면서 연구한 CMG 클러스터의 구동법칙에 대해 알아본다. 본 논문에서는 MP, SR, SR 탈출/회피 구동법칙에 대해 비교를 하고, 각 구동법칙의 성능을 시뮬레이션과 실험을 통해서 확인해보았다.

• 한국IT서비스학회지
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• 제8권4호
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• pp.1-16
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• 2009

Although the Internet has been a important communication tool in modern societies, researchers did not pay attention to its' positive impacts on individual's psychological process. The Internet provides users with a unique environment such as visual isolation, non face-to-face communication, and easiness to escape from social influences. This environment enables people to take free action according to their personality and disclose themselves. The findings indicate that individuals' social use of the Internet may reflect their personality. To fill the research void like this, this study proposes a new research model in which well bing as well as perceived value are positively linked to satisfaction and continuance to use. The statistical results obtained by applying PLS to the valid 150 questionnaires showed that the well bing has stronger positive influence on satisfaction and continuance to use. Therefore, a practical implication is suggested that the web site need to be designed in a way of arousing users' well bing more strongly.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(II)
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• pp.265-270
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• 2003

Though the probability of tunnel fire accident is very low, but critical fatalities are expected when it occurred. In this study the effect of critical safety parameters on tunnel fire accident are examined using probabilistic technique. Fire detection time, smoke spread velocity, passenger escape velocity, flash-over time, and emergency service arrival time are considered. In order to estimate the uncertainties of input parameters Monte Carlo simulation are used, and fatalities for each assumed accident scenarios are obtained as results. For the efficiency of iterative calculation PRA(Probabilistic Risk Analysis) code is developed in this study. As a result fire detection have large effect.

• 한국지역사회생활과학회지
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• 제27권1호
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• pp.67-81
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• 2016

Responsible tourism has become an established area of the tourism industry. This study aims to identify the factors that influence re-participation in responsible tourism in rural Korea. On-site survey was conducted on 436 tourists by seven responsible tourism agencies in Korea. The motivation for responsible tourists was categorized into seven types: family togetherness, escape and relaxation, personal growth, social interaction, various experiences, learning, and natural experience. The estimation of a binary logistic regression model determined the characteristics of responsible tourists who are most likely to opt for re-participation in responsible tourism. Results indicated that important factors for re-participation in responsible tourism were 'age', 'educational level', 'accompany', 'length of stay', and 'motivation'. The results implied that tourists' internal and external factors are important for re-participation in responsible tourism. It is expected that this study will contribute to the market expansion of responsible tourism.