• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.21-25
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• 1998

탈황설비 배관내 연소가스의 삼차원 유동장에 대한 전산해석을 수행하였다. 복잡한 형상으로 주어진 배관내의 유동장 특성을 관찰하고 압력손실을 계산하였다. 특히 안개깃의 설치유무에 따른 유동장 특성 변화 및 압력손실 감소효과를 집중적으로 고찰하였다. 안내깃의 설치에 따라 유량배분이 적절하게 되고 압력손실이 현저하게 줄어듬을 알 수 있었다. 배관에서의 압력손실을 계산하여 배관설계 및 송풍기 용량 산정의 적절성을 확인할 수 있었다.

• Journal of the Economic Geographical Society of Korea
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• v.12 no.4
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• pp.540-556
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• 2009

The hub and spoke network is a critical network-based infrastructure that is widely applied in current transportation and telecommunications systems, including Internets, air transportation networks and highway systems. This main idea of hub location models is to construct a network system which achieves the economy of scale of flows. The main purpose of this study is to introduce new hub location problems that take into account network reliability. Two standard models based on assignment schemes are proposed, and a minimum threshold model is provided as an extension in terms of hub network design. The reliability and interaction potentials of 15 nodes in the U.S. are used to examine model behaviors. According to the type of models and reliability, hubs, and minimum threshold levels, relationships among the flow economy of scale, network costs, and network resiliency are analyzed.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.55-57
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• 2014

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.50-55
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• 2004

Performance predictions of the propulsion system were conducted for a 900㎏ class Canard Rotor/Wing vehicle. The main components of the propulsion system are turbojet engine, exhaust ducts and nozzles. The internal flow of the duct was considered as one-dimensional, compressible and viscous flow. Adequate governing equations including centrifugal force effect were applied to the analysis of the duct flows. Results such as available power, available thrust, engine throttle, mass flow rates, rotor RPM and cruise nozzle area were presented for rotary-wing mode and transition mode.

• KDI Journal of Economic Policy
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• v.17 no.4
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• pp.3-61
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• 1995

기업활동의 범세계화(汎世界化), WTO 출범 등으로 세계경제(世界經濟)의 통합(統合)과 무국경화(無國境化)가 진행되고 있다. 이에 따라 자본 고급인력 등 국제이동성(國際移動性)이 높은 자원들이 유동화(流動化)할 것이고, 그 결과 토지, 사회간접자본, 미숙련 노동력, '경기규칙', 사회 전반적인 과학기술수준, 문화 등 국제이동성(國際移動性)이 낮은 광의(廣義)의 생산요소(生産要素)들이 한 나라의 경제적 특성을 결정하고 경제 기반을 이룰 것이다. 무국경시대(無國境時代)에는 자원배분뿐 아니라 자원유치(資源幽致)가 한 나라의 경제성과에 큰 영향을 미칠 것이며, 따라서 자원유치가 경제운영의 중요한 과제로 등장할 것으로 예상된다. 자원의 국제적(國際的) 유동화(流動化)는 국제이동성(國際移動性)이 높은 생산요소들이 국제이동성이 낮은 생산요소들을 찾아 경제활동의 근거지를 선택하는 것이므로, 무국경시대(無國境時代)에는 저이동성(低移動性) 생산요소(生産要素)들의 양적(量的) 확충(擴充)및 질적(質的) 수준(水準) 제고(提高)를 통한 자원유치(資源誘致)의 가능성이 커지며, 따라서 일부 첨단기술산업의 육성보다는 전반적인 과학기술(科學技術) 수준(水準) 제고(提高)가, 소수의 고급인력 확보보다는 다수(多數) 미숙련(未熟練) 인력(人力)의 질적(質的) 수준(水準) 제고(提高)가 경제성과를 높이는 데 상대적으로 더 중요해진다. 또한 경제적(經濟的) 무국경화(無國境化)는 국적에 관한 속인주의(屬人主義)의 퇴조와 속지주의(屬地主義)의 보편화, 한 나라 국경 안에 상이한 특성을 가진 지방경제(地方經濟)들의 부상, 국내 산업들 사이의 산업연관관계(産業聯關關係) 약화(弱化) 등의 변화를 수반할 것으로 예상된다. 이같은 변화로 개방주의(開放主義) 및 무차별주의(無差別主義)의 확대(擴大)가 불가피하게 되고 특정 산업에 대한 정부지원 및 보호의 근거가 약화되는 반면, 자원배분의 참고단위로서 개별(個別) 경제주체(經濟主體)들의 중요성이 높아지며 그만큼 시장경쟁을 지배하는 '경기규칙(鏡技規則)'의 올바른 정립이 중요해진다. 그러므로 정부는 자원배분에 대한 개업을 축소하고, 저이동성(低移動性) 생산요소(生産要素)들의 양적 질적 수준 제고, 특히 '경기규칙(競技規則)'의 공정성(公正性) 및 투명성(透明性)을 높여야 한다. 즉 정부가 폐쇄성 높은 경제의 지배인으로부터 개방(開放)된 시장경제(市場經濟)의 후견인으로 바뀌어야 한다. 이것이, 시장질서(市場秩序)가 우리를 먹여 살리는 손이라는 인식이나 국제분업(國際分業)이 살 길이라는 확신이 부족한 우리 사회에 무국경시대(無國境時代)가 던지는 어려운 도전(挑戰)이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5661-5668
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• 2012

In the era of water scarcity, saving toilet water is one of the most effective ways to save water. In this study, two-phase flow for the development of highly-efficient toilet has been analysed with VOF(Volume Of Fluid) method. Since the whole model requires extensive computing time, part of the whole model has also been adopted to reduce the analysis time. Four different rim models were considered for flow distribution analysis and sizes of rim holes were found to become more important rather than locations or numbers of rim holes in achieving flow distribution effectively. In addition, velocity and pressure of two-phase flow due to siphon phenomenon have been studied through the analysis of whole model. Therefore, this study provides a variety of fundamental data for the development of highly-efficient toilet.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.51-62
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• 2022

Purpose: This study analyzes accessibility of outdoor evacuation places for earthquake and the accessibility improvement effects when expanding the evacuation places in accessibility-deficient areas. In order to consider real-world evacuees, the accessibility analysis is based on service population not on resident population. Method: Location-allocation model as a GIS-based spatial optimization mode is used to analyze accessibility and vulnerable areas to evacuation places. Of location-allocation problem types, 'Maximize Coverage' method is chosen to allocate as many potential evacuees as possible to evacuation places. And impedence cutoffs or evacuation distances (times) are applied to three classes: 500m (7.5 minutes), 1,000m (15 minutes), and 1,500m (22.5 minutes). Case study area is Jung-gu areas, Seoul as a high-density downtown area. Result: Results show that accessibility-deficient areas and population to evacuation places are much more in service population than in resident population. Accessibility is significantly improved when increases when expanding the evacuation places in accessibility-deficient areas. Yet, accessibility-deficient areas are still remained since available lands are insufficient in the high-density downtown area. Conclusion: The study suggests that temporary evacuation facilities like outdoor evacuation places for earthquake need to consider real potential evacuees based not only on resident population but also on service population. Also, policy measures to provide emergency shelters need to more utilize spatial optimization tools like location-allocation model.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.151-154
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• 2011

$NO_x$ 제어 기술로는 크게 연소 전 탈질, 연소 개선 및 연소 후 탈질 기술로 구분할 수 있으며, 연소 후 탈질 기술에 속하는 SCR은 촉매를 사용하여 $NO_x$를 환원하는 대표적인 배연탈질기술이다. SCR의 $NO_x$ 저감 성능은 촉매 요인(촉매 구성물질, 형태, 공간속도 등)과 배가스의 온도, 유속 분포, 공정 운전 조건 등의 다양한 인자에 의해 좌우되는데 특히, 촉매층으로 유입되는 유동의 균일도는 가장 중요한 요소가 된다. 유동이 균일하지 않을 경우 촉매 전단에 편류가 발생하게 될 것이며 일정 촉매만 사용하게 되어 촉매 사용주기 감소 및 SCR 성능 저하를 초래할 수 있기 때문이다. 본 연구에서는 3차원 수치 해석 기법을 이용하여 설계 초기의 SCR 반응기 내 유동 특성을 모사하여 기류 균일도 여부를 확인하고, SCR 내 유동 균일도를 최적화시키기 위한 설계를 목적으로 설치하는 가이드 베인과 배플, 다공판이 반응기 내부 유동 및 촉매층의 기류 균일도에 미치는 영향에 대하여 연구를 수행하였다. 그 결과, 유동 개선을 위해 인입 덕트 곡관부에 가이드 베인을 설치하여 처리가스를 적절하게 배분시키고, 반응기 상단에 3단 배플을 설치한 결과 반응기 내부 유동의 편류 개선에 매우 효과적임을 알 수 있었다. 또한 다공판을 예비 촉매층 하단부 위치에 추가로 설치함에 따라 유동을 한번 더 완충시킬 수 있어 기류 균일도가 매우 양호해짐을 알 수 있었다.

• Journal of computational fluids engineering
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• v.19 no.3
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• pp.20-23
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• 2014

The flow pattern inside the inlet chamber of the tube side is one of the key parameters influencing on the performances of the shell-and-tube type of heat exchangers(STHE). In order to improve the flow distribution, the baffle shaped as the porous plate is installed in the inlet chambers. In the present study, numerical simulation has been performed to investigate the flow features of the tube side of the STHE in sense of the hydraulic performances. The flow fields have been analysed by the three-dimensional Navier-Stokes solvers with the proper turbulent models. Computational domain is ranged in the whole of the tube side of the STHE. The numerical results showed that the presence of the baffles improves the redistribution of the flow injecting to the tube bundels. The good agreements of the numerical results with the experimental results of PIV measurements have been shown for the validation of the numerical methods adopted in the present papers.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.4
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• pp.418-425
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• 1988

Since conventional computer program is workable only with velocity boundary condition, in practical fluid passage such as clean room which usually have wide inlets and outlets, it is not easy to measure velocity itself because of its vector property. Furthermore a certain assumption of velocity at boundaries may lead to physically unreasonable results. From this motivation, we have developed a computer program to predict whole flow field imposed on pressure-based boundary condition which can be measured by relatively simple method. The only additional velocity boundary condition that should be imposed on to make the problem unique, are no slip condition at all walls and zero cross stream velocity at inlet. The result of present study was compared with that by Bernoulli equation being used practically. They were coincident well each other within 5%, therefore the validity of the present method is proved. In the present work, the flow field in a clean room subject to pressure-based boundary conditions at an inlet and two exits was predicted numerically. The pressure difference between the inlet and the left exit which keeps relatively low pressure among two exits is fixed as 150[Pa] and the pressure at the right exit is varied from zero to 150[Pa] by the increment of 25[Pa]. For each cases the flow characteristics in the clean room, the velocity profile at the inlet, and the flow rate through the two exits was predicted. The flow rate through the right exit imposed on relatively higher pressure than the left exit decreased linearly according to the increase of pressure of the right exit. When the pressure of the right exit is increased enough to cause back flow at the exit, the flow rate is rapidly decreased.