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Think Aloud 훈련이 ADHD 성향이 있는 아동의 주의력 결핍, 충동성 및 사회적 유능성에 미치는 효과
두정훈,손정락 한국임상심리학회 2003 Korean Journal of Clinical Psychology Vol.22 No.1
The purpose of this study was to explore the effects of Think Aloud(TA) training on attention deficit, impulsivity, and social competency of the ADHD-prone children. Fifteen second-grader boys in the elementary school with Abbreviated Conners Teacher Rating Scale(ACTRS) score above 17 were selected. The 7 boys were assigned in the TA training group and the 8 boys were assigned in the control group. The Stratified Test of Attention(STA) for children, the Korean Child Behavior Checklist(K-CBCL) for mother, and the Matson Evaluation of Social Skills with Youngsters (MESSY) for teachers were administerd before and after the TA training. After the all training sessions, there were significant reductions in the attention deficit and the impulsivity in the TA training group. But, there were no significant differences in the social competency between the TA training group and the control group. Finally, the suggestions and limitations of this study were discussed.
내부 냉각유로에서 열전달 강화와 압력손실 감소를 위한 표면 형상체의 개발
두정훈(Jeong Hoon Doo),윤현식(Hyun Sik Yoon),하만영(Man Yeong Ha) 대한기계학회 2009 大韓機械學會論文集B Vol.33 No.6
A new surface shape of an internal cooling passage which largely reduces the pressure drop and enhances the surface heat transfer is proposed in the present study. The surface shape of the cooling passage is consisted of the concave dimple and the riblet inside the dimple which is protruded along the stream-wise direction. Direct Numerical Simulation (DNS) for the fully developed turbulent flow and thermal fields in the cooling passage is conducted. The numerical simulations for five different surface shapes are conducted at the Reynolds number of 2800 based on the mean bulk velocity and channel height and Prandtl number of 0.71 . The driving pressure gradient is adjusted to keep a constant mass flow rate in the x direction. The thermoaerodynamic performance for five different cases used in the present study was assessed in terms of the drag, Nusselt number, Fanning friction factor, volume and area goodness factor in the cooling passage. The value of maximum ratio of drag reduction is -22.86 % , and the value of maximum ratio of Nusselt number augmentation is 7.05% when the riblet angle is 60°. The remarkable point is that the ratio of Nusselt number augmentation has the positive value for the surface shapes which have over 45° of the riblet angle. The maximum volume and area goodness factors are obtained when the riblet angle is 60°.
내부 냉각유로에서 열전달 강화와 압력손실 감소를 위한 표면 형상체의 개발
두정훈(Jeong Hoon Doo),윤현식(Hyun Sik Yoon),하만영(Man Yeong Ha) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
A new surface shape of an internal cooling passage which largely reduces the pressure drop and enhances the surface heat transfer is proposed in the present study. The surface shape of the cooling passage is consisted of the concave dimple and the riblet inside the dimple which is protruded along the stream-wise direction. Direct Numerical Simulation (DNS) for the fully developed turbulent flow and thermal fields in the cooling passage is conducted. The Numerical simulations for the 5 different surface shapes are conducted at the Reynolds number of 2800 based on the mean bulk velocity and channel height and Prandtl number of 0.71. The driving pressure gradient is adjusted to keep a constant mass flow rate in the x direction. The thermoaerodynamic performance for the 5 different cases used in the present study was assessed in terms of the drag, Nusselt number, Fanning friction factor, Volume and Area goodness factor in the cooling passage. The value of maximum ratio of drag reduction is -22.86 [%], and the value of maximum ratio of Nusselt number augmentation is 7.05 [%] when the riblet angle is 60˚ (Case 5). The remarkable point is that the ratio of Nusselt number augmentation has the positive value for the surface shapes which have over 45˚ of the riblet angle. The maximum Volume and Area goodness factor are obtained when the riblet angle is 60˚ (Case 5).
김민성,두정훈,박용갑,윤현식,하만영 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12
This paper presents the results of immersed boundary method–based two-dimension numerical simulations of natural convection in asquare enclosure with an inner circular cylinder at a Prandtl number of 0.7. This simulation spans three decades of Rayleigh number from103 to 106. This study focuses on the effect of the bottom wall temperature variation of the enclosure on thermal and flow structures ofnatural convection in the enclosure. The distribution of streamlines and isotherms in the enclosure depend strongly on the Rayleigh numberand the bottom wall temperature. When the Rayleigh number becomes larger, the variation in the distribution of streamlines and isothermsin the enclosure according to the bottom wall temperature becomes larger, resulting in the large variation in the number, size, andformation of the convection cells in the enclosure. The distribution of local and averaged Nusselt numbers on the cylinder surface and thetop and bottom walls of the enclosure depending on the Rayleigh number and the bottom wall temperature is presented in this paper.
이준명,두정훈,민준기,하만영,손창민 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.3
Diverse cross-corrugated surface geometries were considered to estimate the sensitivity of four variants of k-ε turbulence models (Low Reynolds, standard, RNG and realizable models). The cross-corrugated surfaces considered in this study are a conventional sinusoidal shape and two different asymmetric shapes. The numerical simulations using the steady incompressible Reynolds-averaged NavierStokes (RANS) equations were carried out to obtain the steady solutions of the flow and thermal fields in the unitary cell of the heat exchanger matrix. In addition, the experimental test for the measurement of local convective heat transfer coefficients on the heat transfer surfaces was performed by means of the Transient liquid crystal (TLC) technique in order to compare the numerical results with the measured data. The features on detailed flow structure and corresponding heat transfer in the unitary cell of the matrix type heat exchanger are compared and analyzed against four different turbulence models considered in this study.
회전하는 원형 실린더 주위의 층류 유동장에 관한 수치적 연구
이용석(Yong Suk Lee),두정훈(Jeong Hoon Doo),하만영(Man Yeong Ha),윤현식(Hyun Sik Yoon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
The present study numerically investigates three-dimensional laminar flow past a rotating circular cylinder placed in a uniform stream. For the purpose of a careful analysis of the modification of flow by the effect of the rotation on the flow, numerical simulations are performed at a various range of rotational speeds (0≤α≤2.5) at one Reynolds number of 300. As α increases, flow becomes stabilized and finally a steady state beyond the critical rotational speed. The 3D (three dimensional) wake mode of the stationary cylinder defined at this Reynolds number has been disorganized according to α, which were observed by the visualization of 3D vortical structures. The variation of the Strouhal number is significant when the wake pattern is changed according to the rotational speed. As α increases, the lift increases, whereas the drag decreases.
변압기용 방열기의 방열판 형상이 방열특성에 미치는 영향에 관한 수치적 연구
김영주(Y.J. Kim),두정훈(J.H. Doo),하만영(M.Y. Ha),손성완(S.W. Son),김중경(J.K. Kim),이승호(S.H. Lee) 한국전산유체공학회 2015 한국전산유체공학회지 Vol.20 No.1
In this study, the natural convection phenomenon of the air side and the forced convection phenomenon of the oil side were simulated in the radiator through a 3-D numerical analysis, and the total heat released by the oil side into the radiator heating plate and then to the air side was evaluated. Also, a quantitative analysis was carried out on the effect of each thermal resistance on the overall heat transfer coefficient through a 1-D thermal circuit analysis on the heat transfer mechanisms of the radiators considered in this study. In addition, for the diverse shapes of the heating plates considered in this study, the pressure drops of the oil side were quantitatively compared and evaluated. The temperatures at the air side and the oil side outlets of the radiators with 8 different fin shapes considered in this study had almost similar values showing a difference of +/-3% and, accordingly, the total heat transfer also showed similar heat dissipation performance in all the models. As a result of the 1-D hermal circuit analysis, in all the models considered in this study, while the thermal resistance of the air side accounted for 92% to 96% of the total, that of the oil side was 5 to 7%, and that of the heating plate showed a very small value of 0.02%.
내부에 원형 실린더가 존재하는 기울어진 정사각형 밀폐계 내부의 자연대류 현상에 Prandtl 수가 미치는 영향
문기수(Gisu Mun),두정훈(Jeonghoon Doo),하만영(Man Yeong Ha) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Two-dimensional numerical analysis were conducted to investigate the effect of Prandtl number on the natural convection in a cold outer tilted square enclosure with an inner hot circular cylinder for different Prandtl numbers (10-2≤Pr≤102) and Rayleigh numbers (103≤Ra≤106). The numerical solutions are obtained using immersed boundary method to configurate an inner circular cylinder based on the finite volume method. The outer square enclosure is tilted from γ=0˚ to γ=45˚ by each 5 degrees. The effect of the Prandtl number on natural convection in an enclosure is analyzed by the distribution of the streamlines, isotherms and surface-averaged Nusselt numbers.