• KIEAE Journal
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• v.15 no.1
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• pp.5-12
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• 2015

Recently, natural disasters have unexpectedly occurred at various places in the world and the countermeasure of them become the social issues. Many of victims in disasters need temporary residential facilities above all things and many of researches have been conducted in order to develop simple, safe, and economic designs of them. Moreover, indoor thermal comfort and air quality must be considered in the facilities against a disaster, because clean and healthy space should be provided to the suffered victims. In this research, in order to estimate the indoor environment of the developed modular building for disaster preparation, CFD simulation was conducted in the various condition. In this paper, indoor air quality such as the age of air, the concentration of $CO_2$ was estimated by the case study

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.59-62
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• 2007

연료전지는 수소를 이용하여 전기를 생산하는 발전 시스템으로 운전 중 수소 누출과 폭발의 위험성을 항상 수반하고 있다. 따라서 안전성의 확보를 위해 연료전지 시스템 내부에서 수소 누출 시 유e동 특성으로 인한 특정 부근 농도 정체와 환기의 영향을 파악하는 것이 필요하다. 실험 장치와 전산유체역학 프로그램을 사용하여 챔버 내 수소의 유통 특성과 환기구에 따른 환기의 영향을 확인하였다. 수소의 누출 속도와 양에 따라 유동장의 형태는 크게 변하였으며 환기구의 위치와 크기는 특정 부근의 농도정체와 챔버 내 전체적인 수소 농도에 영향을 미침으로서 안정성을 확보하는 중요한 인자임을 알 수 있었다. 예측 결과를 실제 실험 모델과 비교하여 그 타당성을 검토하였으며 차후 가정용 연료전지 모듈의 환기구 설계에 적용할 수 있다.

• Prospectives of Industrial Chemistry
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• v.22 no.4
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• pp.20-34
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• 2019

수소경제 시대의 도래와 함께 연료전지에 관한 연구가 크게 주목받고 있다. 그중 실험적으로 분석이 어려운 부분에 관하여 비용과 시간이 요구되는 실험적인 방법을 배제할 수 있는 모델링 기법인 전산유체역학(computational flow dynamics, CFD)이 큰 관심을 받고 있다. 연료전지의 연구에 주로 사용되는 전산유체역학에 관한 연구는 열분포, 유체의 흐름, 각종 반응물의 농도, 그리고 전기화학반응 등의 실험적인 분석이 현실적으로 불가능한 부분의 분석으로 통하여 실험을 줄이고도 많은 결과를 얻을 수 있는 연구가 활발하게 진행되고 있다. 본 기고문에서는 전산유체역학을 이용한 연료전지 내부에서 벌어지고 있는 각종 유체, 열, 전기화학반응 등에 관한 연구동향을 소개하고자 한다.

• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.65-77
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• 2016

Modeling for complex reacting flow in Fischer-Tropsch reactor is one of the challenges in the field of Computational Fluid Dynamics (CFD). It is hard to derive each and every reaction rate for all chemical species because Fisher-Tropsch reaction produces many kinds of hydrocarbons which include lots of isomers. To overcome this problem, after analyzing the existing methodologies for reaction rate modeling, non-Anderson-Schulz-Flory methodology is selected to model the detailed reaction rates. In addition, the inside flow has feature of multi-phase flow, and the methodologies for modeling multi-phase flow depend on the interference between the phases, distribution of the dispersed phase, flow pattern, etc. However, existing studies have used a variety of inside flow modeling methodologies with no basis or rationale for the feasibility. Modeling inside flow based on the experimental observation of the flow would be the best way, however, with limited resources we infer the probable regime of inside flow based on conventional fluid dynamics theory; select the appropriate methodology of Mixture model; and perform systematic CFD modeling. The model presented in this study is validated through comparisons between experimental data and simulation results for 10 experimental conditions.

• Journal of Biosystems Engineering
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• v.33 no.6
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• pp.390-395
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• 2008

Current high oil price and the agreement on global climate change prevention have increased worldwide investment and research on renewable energy. In Korea, development of a rapeseed dryer for bio-diesel production has been started in 2007. Usually, rapeseeds are harvested in early summer, because rice cultivation is followed right after rapeseed harvesting. Early harvest and bad summer results in highly moistured rapeseed and development of artificial drying system is required to dry great amount of rapeseed that couldn't be processed by sun drying alone. The rapeseed dryer was modified from an existing circulation type grain dryer. Modification of the dryer was performed with the aid of CFD simulation. Drying test showed that drying rate of rapeseed was 1.51%/h and germination rate reduction was 4.5%p for the drying temperature of $60^{\circ}C$.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.297-306
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• 2014

The paper presents the numerical analysis of wave run-up over rubble-mound breakwaters covered by antifer units using a technique integrating Computer-Aided Design (CAD) and Computational Fluid Dynamics (CFD) software. Direct application of Navier-Stokes equations within armour blocks, is used to provide a more reliable approach to simulate wave run-up over breakwaters. A well-tested Reynolds-averaged Navier-Stokes (RANS) Volume of Fluid (VOF) code (Flow-3D) was adopted for CFD computations. The computed results were compared with experimental data to check the validity of the model. Numerical results showed that the direct three dimensional (3D) simulation method can deliver accurate results for wave run-up over rubble mound breakwaters. The results showed that the placement pattern of antifer units had a great impact on values of wave run-up so that by changing the placement pattern from regular to double pyramid can reduce the wave run-up by approximately 30%. Analysis was done to investigate the influences of surface roughness, energy dissipation in the pores of the armour layer and reduced wave run-up due to inflow into the armour and stone layer.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.455-460
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• 2009

A number of factors combine to make ultraviolet radiation a superior means of water purification for ground water, rainwater harvesting systems and so on. Ultraviolet radiation is capable of destroying all types of bacteria. Additionally, ultraviolet radiation disinfects rapidly without the use of heat or chemical additives which may undesirably alter the composition of water. In a typical operation, water enters the inlet of a UV lamp and flows through the annular space between the quartz sleeve and the outside chamber wall. The irradiated water leaves through the outlet nozzle. Several design features are combined to determine the dosage delivered. The first is Wavelength output of the lamp, the Second is Length of the lamp - when the lamp is mounted parallel to the direction of water flow, the exposure time is proportional to the length of the lamp, the third is Design water flow rate - exposure time is inversely related to the linear flow rate, the forth is Diameter of the purification chamber - since the water itself absorbs UV energy, the delivered dosage diminishes logarithmically with the distance from the lamp. In this paper, It describe the how to design optimal UV disinfection device for ground water and rainwater. To search the optimal design method, it was performed computer simulation with 3D-CFD discrete ordinates model and manufactured prototype. Using proposed design method manufactured prototype applied to disinfection test and proved satisfied performance.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.35-38
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• 2007

The comparisons between measured performance of lab-scale PEMFC and calculation were conducted to understand the detail phenomena of PEMFC for the various inlet oxygen humidity of cathode side. Experiments were performed at $65^{\circ}C$ operation temperature and different inlet humidity conditions such as 40%, 60% and 80%. We used the MEA manufactured by oneself which include $Nafion^{(R)}$ 112 membrane, Nafion solution 20%, and carbon paper(E-TEK). As a result of this experiment, cell performance was getting higher by increasing inlet humidity condition at cathode side because ion conductivity of electrolyte membrane is increased. A 3D CFD simulation model of PEMFC was developed using commercially available CFD code that is one of the STAR-CD module, es-pemfc under same operating conditions. Model calculations results were compared with experimental ones on the polarization curves and calculation results are in good agreement with the experimental ones. Local water distribution and current density inside PEMFC are discussed in detail.

• Journal of computational fluids engineering
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• v.17 no.3
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• pp.11-17
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• 2012

In this study, aerodynamic analyses have been conducted for 4-Bladed Vertical-Axis Wind Turbine (VAWT) configuration and the results are compared with experimental data. Reynolds-averaged Navier-Stokes equation with LES turbulence model is solved for unsteady flow problems. In addition, the computation results by standard k-${\omega}$ and SST k-${\omega}$ turbulence models are also presented and compared. An experiment model of 4-Bladed VAWT model has been designed and constructed herein. Experimental tests for aerodynamic performance of the present VAWT model are practically conducted using the vehicle mounted testing system. Comparison results between the experiment and the computational fluid dynamics (CFD) analyses are presented in order to show the accuracy of CFD analyses using the different turbulent models.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.513-523
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• 2014

A fluid transport technique is a key issue for the development of microfluidic systems. In this study, the movement of a droplet on horizontal hydrophilic/hydrophobic surfaces, which is a new concept to transport droplets without external power sources that was recently proposed by the author, was simulated using an in-house solution code(PowerCFD). This code employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with interface capturing method(CICSAM) in a volume of fluid(VOF) scheme for phase interface capturing. The droplet transport mechanism is examined through numerical results that include velocity vectors, pressure contours, and total kinetic energy inside and around the droplet.