• Wind and Structures
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• v.22 no.4
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• pp.409-428
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• 2016

The mechanical and aerodynamic effect of building shape plays a dominate role in the pedestrian level wind environment. These effects have been presented in numerous studies and are available in many wind codes. However, most studies have focused on wind flow around conventional buildings and are limited to few wind directions. The present study investigated wind circulation in the re-entrant corners of cross-shaped high-rise buildings from various wind directions. The investigation focused on the pedestrian level wind environment in the re-entrant corners with different aspect ratios of building arrangements. Ninety cases of case study arrangements were evaluated using wind tunnel experimentation. The results show that for adequate wind circulation in the re-entrant corners, building orientations and separations play a critical role. Furthermore, in normal wind incident directions and at a high aspect ratio, poor wind flow was observed in the re-entrant corners. Moreover, it was noted that an optimized building orientation and aspect ratio significantly improved the wind flow in re-entrant corners and through passages. In addition, it was observed that oblique wind incident direction increased wind circulation in the re-entrant corners and through passages.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2589-2593
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• 2008

In a fuel cell vehicle using polymer electrolyte membrane fuel cell(PEMFC), hydrogen is over-supplied to gain higher stack efficiency. So it is needed considering fuel efficiency to re-circulate hydrogen which is not reacted in stack. And to re-circulate hydrogen, a blower or an ejector is used. Ejector re-circulation system has several merits compared with blower system, for example no parasite energy, simple structure and no lubrication system. But the secondary flow of an ejector in fuel cell vehicle, has high humidity because of crossover problem in stack. Therefore in this paper, ejector is designed by 1-D modeling and CFD with the primary and secondary flow of hydrogen. And the ejector which has the primary and secondary flow of air, is designed to have the same Reynolds number and Mach number at the nozzle exit as the hydrogen ejector's. And this air ejector is tested while the humidity of the secondary flow is varied.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.215-218
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• 2003

A 2R O/E/O wavelength converter is useful for bit rate transparency, though it has a limit on cascadability due to timing-jitter accumulation. In this paper, we propose a nonlinear signal model which is more practical than the commonly used sine wave model. With our model, we theoretically analyzed the effects of timing-jitter and the cascadability of a 2R O/E/O wavelength converter. To confirm the theoretical results, we measured the cascadability in a 40-km re-circulation loop for 10 Gb/s signal.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.59.5-60
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• 2008

• Progress in Superconductivity and Cryogenics
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• v.15 no.3
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• pp.49-52
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• 2013

An experiment to investigate the natural circulation of a cryogen has been performed. The study is motivated mainly by our recent development of cryogenic cooling system for prototype superconducting cyclotron without any circulating pump. In the natural circulation loop system, a cooling channel is attached on the outer surface of the aluminium block and the liquid nitrogen passes through inside of the channel to cool the block indirectly. A cryocooler as a heat sink is located at the top to re-condense cryogenic vapor coming from the aluminium block in which electrical heater is installed as a heat source. The main dimensions are determined using the relevant analysis and the natural circulation loop is successfully fabricated. The temperature distributions in the loop are measured during initial cool-down process and in steady state, from which the modified Grashof numbers are calculated and compared with the existing correlation estimated with one-dimensional analysis for steady state flow.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.299-302
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• 2009

The objective of the present study is to analyze the transient flow through theejector system with the help of a computational fluid dynamics (CFD) method. An attempt is made to investigate the interesting and conflicting phenomenon of the infinite entrainment into the primary stream without an infinite mass supply from the secondary chamber. The results obtained show that the one and only condition in which an infinite mass entrainment can be possible in such types of ejectors is the generation of a re-circulation zone near the primary nozzle exit. The flow in the secondary chamber attains a state of dynamic equilibrium of pressures at the onset of the recirculation zone. A steady flow in the ejector system is valid only after this point.

• Journal of Fashion Business
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• v.26 no.4
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• pp.136-153
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• 2022

The fashion industry is considered hazardous and a threatened to the environment. Due the negative perception, the industry should focus on sustainability as a social role. Therefore, several redesign fashion collaborations mainly focusing on renewing abandoned resources are already in place. The research method was based on previous studies, and 3 characteristics were derived: Redesign collaboration between fashion companies, Redesign collaboration between fashion & heterogeneous industries, and Redesign collaboration between the fashion industry & non-profit organizations. Those 3 characteristics were reviewed using 4 criteria. First, to establish and maximize the sustainable brand image and to be the best examples in environmental management, the organization endeavors to collaborate with various industries, institutions, and designers. Second is the expansion of the customer network through the spread of value consumption. Third is the creation of new values through a resource circulation structure. This means that the resource circulation structure system helps the partners to minimize on wastage. Fourth is the spread of de-boundary lines and the possibility of brand growth. Through collaboration with other industries, the boundaries of materials used in the fashion industry started to blur, thus expanding the continuous brand growth potential. The study derived the characteristics of redesign collaboration by systematically analyzing the cases. Further, the study looks forward to analyzing the characteristics of the products processed by redesign fashion collaborations in future research.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3320-3325
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• 2023

The scaled water-cooled Reactor Cavity Cooling System (RCCS) experimental facility reproduces a passive safety feature to be implemented in Generation IV nuclear reactors. It keeps the reactor cavity and other internal structures in operational conditions by removing heat leakage from the reactor pressure vessel. The present work uses Flownex one-dimensional thermal-fluid code to model the facility and predict the experimental thermal-hydraulic behavior. Two representative steady-state cases defined by the bulk volumetric flow rate are simulated (Re = 2,409 and Re = 11,524). Results of the cavity outlet temperature, risers' temperature profile, and volumetric flow split in the cooling panel are also compared with the experimental data and RELAP system code simulations. The comparisons are in reasonable agreement with the previous studies, demonstrating the ability of Flownex to simulate the RCCS behavior. It is found that the low Re case of 2,409, temperature and flow split are evenly distributed across the risers. On the contrary, there's an asymmetry trend in both temperature and flow split distributions for the high Re case of 11,524.

• Korean Institute of Interior Design Journal
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• v.24 no.5
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• pp.144-152
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• 2015

In modern city, art museum is regarded as significant institutions because it includes educational roles beyond the means of facilities for historical exhibitions. Based on these flow, various research of museum's space with view from the operational point to the spatial analysis point has been approached. Moreover, it is required to address human behavior in art museum space on the ground that lots of audience move simultaneously. In the field of interior architecture, it is also necessary to analyze how design elements affect the human behavior directly and use the method of controling a circulation. In this research, based on the role and importance of the basic components of the interior space, re-interprets the exhibition space based on the relevant theory, to comprehensively examine the influence the shape of the space is on the substantially walking behavior. Therefore, first is to determine whether the spatial type corresponding to the position of the connectors in the exhibition space. Second is to conduct the investigation observation for gathering the actual viewing exhibition circulation. Finally, it analyzed whether the observed actual circulation and planned circulation matched. As the result, the position of the connectors is that causes the difference of the spatial configuration, which affects the viewing circulation was found. The significance of the research is to present the form to plans of the interior space as a method of reducing congestion perception of viewing circulation.

• The Journal of the Korea Contents Association
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• v.16 no.9
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• pp.198-210
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• 2016

The purpose of this study is to analyze the tourists' circulations and behaviors at one of the representative dark tourism sites in Seoul, named Seodaemun Prison History Hall. This study conducts direct observation and behaviour tracking or follow-up survey based on traffic circulation and visitors' Muse-Ethogram extracted from the previous studies. The result of tourists' actual circulations shows that main tourists' flows of study areas consist of 3 approaches; suggested, unstructured and directed approaches. And tourists' behaviors such as moving(M), stop looking(SL), and reading(RE) reveal with the highest frequency. This study finds the 'expressing feeling(EXP)' as a new visitor' behavior in dark tourism site. The highest frequency of visitors' movement patterns is stop looking-reading-move(SL-RE-M). The results of this study could be used as a planning and design guidelines of dark tourism related to exhibition circulation, visitors' behaviors and development of exhibition content.