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김종수,조강래,Kim, J.S.,Cho, K.R. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.2
The effects of duct inlet conditions on fan characteristics and upper wind velocity fields were investigated for two kinds of impellers. As the duct inlet condition, the relative positions between duct inlet and fan impeller and the size of baffle plate mounted on a duct inlet were selected. The 3-dimensional velocity components in flow fields were measured by a 5-holes pitot tube. From the results of measurements, it was found that the size of baffle plate scarecely effect on upper wind flow fields and characteristics of fan. It was also confirmed that the upper wind velocity distributions can be estimated by the potential flow field with large baffle plate at duct inlet.
김종수,강정길,Kim, J.S.,Kang, J.K. 대한설비공학회 1991 설비공학 논문집 Vol.3 No.4
Recently, automotive air conditioning system manufacturers have been made a great efforts on the system compactness and high efficiency. This growing interest comes improvements in evaporator thermal performance, one of the most important factors affecting the performance of air conditioning system. In order to improve design of compact type evaporator, this study executes performs to develop a computer program for evaporator thermal performance prediction of automotive air conditioning system. The brief summaries of this study are as follows: 1) To predict the overall thermal performance of serpentine type evaporator, the new simulating method is developed. 2) The calculations are performed as functions of oil mass concentration and refrigerant two-phase distribution at inlet manifold of evaporator. 3) The validity of this simulating program is confirmed by comparing the predicted thermal performance results to experimental results of practical available evaporator. 4) Based on these results, suggestions are made to improve the thermal performance of evaporator.
김종수(J.S. Kim),김형식(H.S. Kim),현기탁(K.T. Hyun) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.1
Acoustic pressure field around the centrifugal fan is predicted by a aero-acoustic splitting method. Unsteady flow field is obtained by solving the incompressible Navier-Stokes equations using commercial code, while the acoustic waves generated inside the centrifugal fan and shroud are predicted by solving the far field acoustics analysis. Computational results show that the acoustic waves of BPF tone are generated by interactions of the blades with the shroud. Acoustic results is validated by experimental results This paper describes the influence of geometric parameters on the noise generation from the section of blades and shroud. One of the effective ways to reduce BPF noise is optimization method using Genetic Algorithm, which effectively minimize eccentricity, is suggested. New improving design was developed by optimization method.
김종수(J.S. Kim),조태수(T.S. Cho),안형택(H.T. Ahn) 한국전산유체공학회 2016 한국전산유체공학회지 Vol.21 No.3
In speed skiing, aerodynamic forces play an important role in determining performance of the skier. To predict aerodynamic effects of the posture of the skier on alpine downhill skiing, we constructed equation of motion of the skier and performed the corresponding CFD simulations. Comparing drag and lift of three different skier postures, it has been shown that drag decreases significantly by tucking upper body to lower body and stretching arms forward. Also, aerodynamic lift which worked as downforce in standing posture worked upward in tuck posture, reducing friction force between snow and ski. This indicates that tuck posture have advantages over standing posture in dual mechanism, namely by reducing drag and also increasing lift. By this two-dimensional initial study we could reveal the general tendency of the aerodynamic force over the skiers body. This study not only provides a theoretical foundation for the athletes to understand the aerodynamic effects of skier postures but also shed a light on towards more accurate and rational three-dimensional CFD simulation of skiers in the near future study.
전산유체역학을 활용한 가전 제품용 원심팬 블레이드의 단계별 형상 최적화
김종수(J.S. Kim),강태곤(T.G. Kang) 한국전산유체공학회 2016 한국전산유체공학회지 Vol.21 No.3
We conducted a multi-stage optimization to secure the desired performance of a centrifugal fan for home appliance in an early stage of product development. In optimization, the static pressure at the outlet of the fan is chosen as an objective function that is to be maximized, providing the required flow rate at the operating point of the fan. The optimization procedure begins with parameters for an initial baseline fan design. The baseline design is optimized by using a commercial optimization package. Accordingly, the corresponding blade models with a set of geometrical parameters are generated. Flow through a fan is simulated by solving the Reynolds-averaged Navier-Stokes equations. A multi-stage optimization scheme is employed to determine the family of optimum values for the parameters, leading to the pressure increase at the outlet of the fan. To validate the numerically obtained optimal design parameters, we fabricated the three types of fans using rapid prototyping and assessed the performance using a fan tester. Experimental results show that the design parameters at each stage satisfy the goal of optimization. The multi-stage optimization process turned out to be a useful tool in the development of a centrifugal fan.
박막 형광체 ZnGa₂O₄:Mn<SUP>2+</SUP>의 RF Magnetron Sputtering법을 이용한 생장
김종수(J. S. Kim),이성훈(S. H. Lee),박재홍(J. H. Park),박형원(H. W. Park),최진철(J. C. Choi),박홍이(H. L. Park) 한국진공학회(ASCT) 2006 Applied Science and Convergence Technology Vol.15 No.4
RF magnetron sputtering법을 이용하여 quartz 기판 위에 spinel 구조의 ZnGa₂O₄:Mn<SUP>2+</SUP> 박막 형광체를 상온에서 증착 하였다. 후 열처리 온도에 따라 박막의 결정성, 표면 거칠기와 조성비가 변하였으며 이는 박막 형광체의 발광특성에 영향을 주었다. 후 열처리 온도가 500 ℃에서 900 ℃로 올라감에 따라, 후 열처리 온도가 700 ℃일 때 가장 낮은 수치의 표면 거칠기를 보였고 이로 인한 낮은 외부 양자 효율로 인하여 발광특성이 좋지 않았다. 후 열처리 온도가 800 ℃일때 결정화 정도가 좋았으며 적당한 표면 거칠기와 화학적 조성비로 인해 최적의 발광특성을 보였다. 반면 후 열처리 온도가 900 ℃일 때 결정성은 가장 좋았으나 Zn의 높은 증기압으로 인한 화학적 조성비의 깨짐으로 발광특성이 좋지 못하였다. Thin-film ZnGa₂O₄:Mn<SUP>2+</SUP> phosphors of spinel structure were grown on quartz substrate by RF magnetron sputtering method at room temperature. As an increase of post-annealing temperatures, crystallinity, surface roughness and stoichiometry of thin films were varied. At the post-annealing temperatures of 500 ℃ and 600 ℃, the luminescence intensity was poor due to the poor crystallinity. The smallest surface roughness was observed at the sample post-annealed at 700 ℃ leading to low external extraction efficiency, and poor luminescence intensity. The highest luminescence intensity was shown at the sample post-annealed at 800 ℃. It was because both the surface roughness and crystallnity were optimized. On the other hand, at 900 ℃, the luminescence intensity was poor due to the violation of stoichiometry.