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윤명섭(Myung-Sup Yoon),이동혁(Dong-Hyuk Yi),윤원식(Won-Sik Yoon),서명교(Myung-Kyo Seo),유승엽(Seung-Yup Ryu) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
Supervised machine learning technique was applied to accurately predict the performance of the clean room air conditioner (CRAC) installed in the field. The performance of two neural networks was compared. One is the control group neural network using the laboratory sensor data and the other is the experimental group neural network using the product sensor data as an input. In both cases, they share laboratory performance results as an output label. Training data set of 2,816 combinations were acquired in the laboratory for the various indoor climate, outdoor climate and CRAC fan output conditions. When predicted with two trained ANNs, the control group showed better results thant the experimental group. In addition, the experimental group ANN performance prediction showed relatively more accurate results than the performance values calculated directly from the product sensors.
동심원 형상 홈이 파여진 원판이 회전하고 있을 때의 실린더 내부유동에 관한 연구
윤명섭(Myung Sup Yoon),박준상(Jun Sang Park),현재민(Jae Min Hyun) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
A numerical study is made of a flow in a cylinder with a rotating grooved endwall disk. The aim is<br/> to describe differences in the flow fields when there is concentrically-grooved obstacle characterized by<br/> amplitude(a) and wave number(N). The Reynolds number(Re) is varied from 103 to 104 and the aspect<br/> ratio(Ar) fixed to 1.0 for the most part of the simulation. For the various cases of amplitude(a) and<br/> wave number(N), numerical results are acquired. As the endwall groove roughness increases until<br/> certain limit, the interior azimuthal velocity component(v) increases drastically. But over the limit, the<br/> swirl motion chararcterized by velocity v decreases and finally it approaches much alike Ar=1.0-a case.<br/> The reason of activating swirl motion is based on increasing of torque transported by endwall disk.<br/> Torque coefficients(CT) are aquired for the various (a,N,Re) combinations and the limiting phenomena<br/> of swirl motion activation is explained.
윤명섭(Myung Sup Yoon),박준상(Jun Sang Park),현재민(Jae Min Hyun) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
A study is made of time-dependent flow of a viscous fluid driven by an infinite oscillating disk. Numerical solutions to the Navier-Stokes equations are obtained for the flow over a disk torsionally rotating at a velocity Ωcosλt. Details of the three-component velocity field are examined at high Reynolds number. The value of the nondimensional amplitude of disk oscillation, ε=Ω/λ, encompas ses a range up to ε≥O(1). The numerical results for the case of ε≪1 are consistent with the predictions of the earlier analytical model. The azimuthal flow is largely confined to the Stokes layer thickness. The steady meridional streaming at finite values of ε is exhibited. Finally, disk skin friction and heat transfer enhancement are analyzed.
윤명섭(Myung-Sup Yoon),이동혁(Dong-Hyuk Yi),윤원식(Won-Sik Yoon),서명교(Myung-Kyo Seo),유승엽(Seung-Yup Ryu) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
Supervised machine learning technique was applied to accurately predict the performance of the clean room air conditioner (CRAC) installed in the field. The performance of two neural networks was compared. One is the control group neural network using the laboratory sensor data and the other is the experimental group neural network using the product sensor data as an input. In both cases, they share laboratory performance results as an output label. Training data set of 2,816 combinations were acquired in the laboratory for the various indoor climate, outdoor climate and CRAC fan output conditions. When predicted with two trained ANNs, the control group showed better results thant the experimental group. In addition, the experimental group ANN performance prediction showed relatively more accurate results than the performance values calculated directly from the product sensors.
윤명섭(Myung Sup Yoon),박준상(Jun Sang Park),현재민(Jae Min Hyun) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
In this paper, the MHD flow of an incompressible, viscous and electrically conducting fluid above an infinite rotating axisymmetric wavy disk is analyzed by using transformed boundary layer equations. The fluid is subjected to an external uniform magnetic field parallel to the axis of the rotation. Generally, the flow fields in the r-z plane are weakened as the magnetic parameter becomes larger, thus the radial skin friction coefficient itself and the surface wave effect on it decrease. But the torque required to maintain steady rotation of the disk increases.
박준상(Jun Sang Park),윤명섭(Myung Sup Yoon),현재민(Jae Min Hyun) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
An analytic study has made of slip velocity on the rotating disk with micro surface roughness. The system Ekman number, E≡v/ΩR², has assumed to be very small value, in which v denotes kinematic viscosity of the fluid, Ω rotational angular velocity of the disk and R radius of the disk. Magnitude of the surface roughness is represented by a characteristic length scale, δ, as equal to or less than the thickness of Ekman boundary layer, i.e., δ ≤ O(E1/2). Implementing a strained coordinate method to the Ekman layer flow on a rotating disk with axisymmetric micro-roughness surface, the flow field solutions are obtained in an explicit formula, and then effective slip velocity condition are clearly defined at the geometrical mean plane. The results have been confirmed by comparing with numerical data. Several in-depth physics underlying the solution are discussed.