• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.178-179
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• 2005

Numerical and experimental investigation of incompressible turbulent flow and heat transfer through square channels with varying number of ribbed walls were conducted to determined pressure drop and heat transfer. The CFX solver used for the computation. The rough walls have a $45^0$ inclined square rib. Uniform heat flux is maintained on whole inner heat transfer channel area. The numerical results agreed well with experimental data that obtained for 7600$D_h$) of 0.0667. The results show that values of local heat transfer coefficient and friction factor increase with an increasing number of ribbed walls.

• 대한토목학회논문집
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• 제26권1D호
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• pp.185-193
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• 2006

현재 시행되고 있는 사전환경성검토는 부분 항목별 수치분석이 이루어지고 있어 종합적인 사전환경성검토가 어려운 실정이다. 또한, 수치자료의 활용이 미흡하여 환경성검토 분석결과의 객관성이 저하되고 있고, 평가비용과 시간도 많이 소요되고 있다. 본 연구에서는 8개 사전환경성 검토요소에 대한 지리정보체계의 공간분석기능을 도입하였으며, 개별 요소들의 평가결과를 통한 종합적인 검토를 수행할 수 있도록 사전 환경성검토 GIS 의사결정시스템을 구축하였다. 본 연구에서 개발한 사전환경성 검토 GIS 의사결정시스템과 기 구축된 GIS 데이터를 활용을 통해 환경성 검토에 객관성이 충족 및 시간 비용 절감이 가능하여 사업초기에 도로 노선선정 시 사전환경성 검토에 활용 가능할 것이다. 또한, 본 연구 개발된 시스템을 통하여 수치적이고 시각적인 자료를 활용한 평가로 주민의 합의를 보다 용이하게 이끌어 낼 수 있고, 사업초기에 비용과 시간을 절감하면서 도로건설에 따른 환경성을 검토할 수 있을 것으로 기대된다.

• 한국지리정보학회지
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• 제10권2호
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• pp.152-163
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• 2007

현재 시행되고 있는 사전환경성검토는 부분 항목별 수치분석이 이루어지고 있어 종합적인 사전환경성검토가 어려운 실정이다. 또한, 수치자료의 활용이 미흡하여 환경성검토 분석결과의 객관성이 저하되고 있고, 평가비용과 시간도 많이 소요되고 있다. 본 연구에서는 8개 사전환경성 검토요소에 대한 지리정보체계의 공간분석기능을 도입하였으며, 개별 요소들의 평가결과를 통한 종합적인 검토를 수행할 수 있도록 계층분석기법을 활용한 사전환경성검토 GIS 의사결정시스템을 구축하였다. 본 연구에서 개발한 사전환경성 검토 GIS 의사결정 시스템과 기 구축된 GIS 데이터의 활용을 통해 환경성 검토에 객관성의 충족 및 시간 비용 절감이 가능하여 사업초기에 도로노선선정 시 사전환경성 검토에 활용 가능할 것이다. 또한, 본 연구에서 개발된 시스템을 통하여 수치적이고 시각적인 자료를 활용한 평가로 주민의 합의를 보다 용이하게 이끌어 낼 수 있고, 사업초기에 비용과 시간을 절감하면서 도로건설에 따른 환경성을 검토할 수 있을 것으로 기대된다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권1호
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• pp.110-116
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• 2016

In this study an attempt has been made to study the hydrodynamic performance of pumpjet propulsor. Numerical investigation based on the Reynolds Averaged NaviereStokes (RANS) computational fluid dynamics (CFD) method has been carried out. The structured grid and SST ${\kappa}-{\omega}$ turbulence model have been applied. The numerical simulations of open water performance of marine propeller E779A are carried out with different advance ratios to verify the numerical simulation method. Results show that the thrust and the torque are in good agreements with experimental data. The grid independent inspection is applied to verify accuracy of numerical simulation grid. The numerical predictions of hydrodynamic performance of pumpjet propulsor are carried out with different advance ratios. Results indicate that the rotor provides the main thrust of propulsor and the balance performance of propulsor is generally satisfactory. Additionally, the curve of propulsor efficiency is in good agreement with experimental data. Furthermore, the pressure distributions around rotor and stator blades are reasonable. Beyond that, the existence of tip clearance accounts for the appearance of tip vortex that leads to a further loss in efficiency and a probability of cavitation phenomenon.

• 한국소음진동공학회논문집
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• 제24권3호
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• pp.180-188
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• 2014

현대자동차그룹은 HSM이라고 불리는 간략화된 차량 모델에 대하여 썬루프 버페팅 현상의 실험적인 조사를 시행하였다. 현대자동차그룹은 어떤 CFD솔버가 충분한 정확도를 가지고 썬루프 버페팅 현상을 예측하는지 조사하기 위해 상용CFD공급업체의 참여를 요청하였다. ANSYS Korea는 이번 조사에 참여하여 ANSYS fluent를 이용하여 HSM의 썬루프 버페팅에 대한 수치해석을 수행하였다. 먼저 유동장 검증을 위해 풍속 60 km/h에 대하여 썬루프가 닫힌 HSM모델에 대하여 해석을 수행하였다. HSM상부 면의 세 지점에서 속도 분포를 예측하였고, 이는 시험결과와 비교되었다. 그런 다음 고해상도 난류 모델인 DES를 이용한 해석이 전 풍속영역에 걸쳐 수행되었다. 버페팅 주파수와 버페팅 음압레벨이 예측되었고, 이는 시험결과와 비교되었다. 이를 통해 실제 차량 개발을 위한 CFD의 예측 가능성에 대하여 결론을 얻을 수 있었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.236-242
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• 2007

A theoretical and numerical investigation is performed on the flow in a micronozzle for precision-controlled seal dispenser. The working fluid is a highly viscous epoxy used as sealant in producing LCD panels, which contains a number of tiny solid spacers. Flow analysis is conducted in order to achieve the optimal design oj internal geometry of a nozzle. A simplified design analysis methodology is proposed for predicting the flow in the nozzle based on the assumption that the Reynolds number is much less than O(1). The parallel numerical computations are performed by using a CFD package FLUENT. Comparison discloses that the theoretical model gives a good prediction on the distribution of pressure and wall shear stress in the nozzle. However, the theoretical model has a difficulty in predicting the maximum wall shear stress as found in a limited region near edge by numerical computation. The theoretical and numerical simulations provide the good guideline for designing a dispensing micronozzle.

• Earthquakes and Structures
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• 제14권2호
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• pp.179-186
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• 2018

We present the accurate investigation the seismic behavior of the gravity retaining wall built near rock face based on numerical method. The retaining wall is a useful structure in geotechnical engineering, where the earthquake is a common phenomenon; therefore, the evaluation of the behavior of the retaining wall during an earthquake is essential. However, in all previous studies, the backfill behind the wall was usually approximated by a homogeneous region, while in contrast, in practice, in many cases retaining walls are used to support the soil pressure in, inhomogeneous, mountainous area. This suggests an accurate investigation of the problem, i.e., numerical analysis. The numerical results will be compared with some of recently proposed analytical methods to show the accuracy of the proposed method. We show that increasing the volume of the rock face yields decreasing the permanent horizontal displacement of the gravity retaining wall built near rock face. Besides, we see that the permanent horizontal displacement of the gravity retaining wall with homogenous backfill is more than permanent horizontal displacement of the gravity retaining wall case of the built near rock face in different frequency contents.

• International Journal of Fluid Machinery and Systems
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• 제5권4호
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• pp.168-173
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• 2012

This paper presents a numerical investigation on the aerodynamic performance according to the application of splitter blades in an impeller of a centrifugal fan used for a refuse collection system. Numerical analysis of a centrifugal fan was carried out by solving three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. A validation of numerical results was conducted by comparison with experimental data for the pressure and efficiency. From analyses of the internal flow field of the reference fan, the losses by the reverse-flows were observed in the region of the blade passage. In order to reduce these losses and enhance fan performance, two splitter blades were applied evenly between the main blades, and centrifugal impellers having the different numbers of the main blades were tested with their application. Throughout the numerical analyses of the centrifugal fan with splitter blades, it was found that the reverse-flow regions in the blade passage can be reduced by controlling the main blade numbers with splitter blades. The application of splitter blades in a centrifugal fan leads to significant improvement in the overall fan performance.

• 한국전산유체공학회지
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• 제12권4호
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• pp.54-60
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• 2007

A theoretical and numerical investigation is performed on the flow in a micronozzle for precision-controlled sealant dispenser. The working fluid is a highly viscous epoxy used as sealant in producing LCD panels, which contains a number of tiny solid spacers. Flow analysis is conducted in order to achieve the optimal design of internal geometry of a nozzle. A simplified design analysis methodology is proposed for predicting the flow in the nozzle based on the assumption that the Reynolds number is much less than O(1). The parallel numerical computations are performed by using a CFD package FLUENT. Comparison discloses that the theoretical model gives a good prediction on the distribution of pressure and wall shear stress in the nozzle. However, the theoretical model has a difficulty in predicting the maximum wall shear stress as found in a limited region near edge by numerical computation. The theoretical and numerical simulations provide the good guideline for designing a dispensing micronozzle.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.27-36
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• 2020

Natural convection and thermal stratification phenomena are found in large water pools that are being used as heat sinks for decay heat removal from the reactor core using passive heat removal systems. In this study, the two-phase (water and air) natural convection and thermal stratification phenomena with conjugate heat transfer in the rectangular enclosure were investigated numerically using ANSYS Fluent 17.2 code. The transient numerical simulations of these phenomena in the full-scale computational domain of the experimental facility were performed. Generation of water vapour bubbles around the heater rod and evaporation phenomena were included in this numerical investigation. The results of numerical simulations are in good agreement with experimental measurements. This shows that the natural convection is formed in region above the heater rod and the water is thermally stratified in the region below the heater rod. The heat from higher region and from the heater rod is transferred to the lower region via conduction. The thermal stratification disappears and the water becomes well mixed, only after the water temperature reaches the saturation temperature and boiling starts. The developed modelling approach and obtained results provide guidelines for numerical investigations of thermal-hydraulic processes in the water pools for passive residual heat removal systems or spent nuclear fuel pools considering the concreate walls of the pool and main room above the pool.