• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2005년도 추계학술대회 논문집
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• pp.28-35
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• 2005

Experiments were conducted to show the characteristics of the flow on triple parallel plane impinging jets. Measurements of mean velocity components and turbulent intensities were carried out with a particle image velocimetry(PIV) to investigate the flow field generated by the air issued from three identical plane parallel nozzles and mixed with the ambient air. The measurements range of these experiments were Reynolds number of 5000 and 1000 based on the nozzle width and the case of nozzle-to-plate distances were two times, six times and ten times the width of the nozzle. Results show that recirculation region of Re=5000 is the stronger than that of Re=1000. Therefore, velocity loss of centerline for Re=5000 that shows strongly recirculation region takes effect greatly.

• Journal of Mechanical Science and Technology
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• 제17권11호
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• pp.1628-1637
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• 2003

The vortex-induced vibrations of a circular cylinder at low Reynolds (Re) numbers are simulated by applying a method of the two-dimensional computational fluid dynamics coupled with the structural dynamics based on the multi-physics. The fluid solver is first tested on the case of a fixed cylinder at Re$\leq$160, and shows a good agreement with the previous high-resolution numerical results. The present study then reports on the detailed findings concerning the vibrations of an elastic cylinder with two degrees of translational freedom for a number of cases in which Re is fixed at 200, a reduced damping parameter Sg=0.01, 0.1, 1.0, 10.0 and the mass ratio M$\^$*/ = 1, 10.

• Journal of information and communication convergence engineering
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• 제7권3호
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• pp.351-355
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• 2009

The amount of incoming e-mails is increasing rapidly due to the wide usage of Internet. We often group e-mails into categories for maintaining e-mail efficiently. However reading the email messages and classifying them is still tedious task. Moreover, the number of e-mails and manual classifying is increasing everyday. So, automatic e-mail classification is important techniques. In this paper, we propose a multi-way e-mail classification method that uses PCA for automatic category generation and dynamic category hierarchy for re-organizing e-mail categories. It classifies a huge amount of receiving e-mail messages automatically, efficiently, and accurately.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.392-395
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• 2006

The configuration of coaxial co-rotating contained in shroud provides a useful model for investigating the characteristics of flow in the HDD. Reynolds number is defined as $Re_R={\Omega}{R_o}^2/{\upsilon},\;Re_H={\Omega}R_oH/{\upsilon}$ in present study. An experimental investigation was performed for turbulence profiles and PSD distribution and vortices frequency behavior for various range of $Re_R=2.43{\times}10^4{\sim}3.61{\times}10^5$. A laser Doppler anemometry (LDA) is used to obtain the velocity field of unobstructed co-rotating disks flow. Airflow pattern visualization between inner and outer region was compared with turbulence profiles measured from LDA. Outer detached shear layer and dead-zone without oscillating velocity fluctuation to circumferential mean were quantitively traced.

• 한국주거학회논문집
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• 제2권1호
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• pp.57-68
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• 1991

This study is concerned with the functions of dwelling space effected by the tendency that the number of furniture in the household has increased in recent years. The functions of dwelling space were grasped on the basis of dwelling - behavior tenitories. The possession of furniture was surveyed In 144 units of apartment house. Observation with questionnaire was carried out through pilot and main survey. 1) The dwelling - behavior territories of Anbang, Living Room and D.K. each were classified into 4 kinds. These territories were assorted into two categories ; first, the similar territories were integrated and specific various territories formatted, second, new kind dwelling spaces were required2) Accordingly, Anbang have to be re - setted up Anbang and storage, Living Room and D.K. re - setted up L.D.K. and Utility. In this way, it coudld be possible, that creative reasonable space were formated for more satisfactory. Therefore relationships between furniture possession and the usage of dwelling spaces wre identified.

• Journal of Advanced Marine Engineering and Technology
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• 제23권2호
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• pp.176-183
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• 1999

This paper is aimed to investigate behaviour of vortex in 2-D step cavity with high Reynolds numbers$(3.2{\times}10^{3},\;10^{4},\;3{\times}10^{4},\;5{\times}10^{4}\;and\;7{\times}10^{4})$. The SOLA algorithm which is MAC type was adopted to solution method computing the flow field on irregular grid. In case of $Re=7{\times}10^{4}$ flow behavior is steady bu periodic unsteady sinusoidal fluctuation of local velocity and kinetic energy is found for $Re=10^{4}$ Continuous movements of small eddies in the secondary flow regions are discov-ered for $3{\times}10^{4}$ Generation of eddies and their active migrating behavior are detected over $Re=5{\times}10^{4}$ resulting in complete unsteady and non-linear flow characteristics Furthermore a typhoon-like vortex(TLV) appears intermittently and rotates along the separation regions and boundary layers.

• 교육시설 논문지
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• 제20권1호
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• pp.3-14
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• 2013

The following research, analysis about an integral part of current elementary classroom, has been done to grasp the importance of re-organization of an elementary school classroom. For the research process 11 schools, 60 classrooms have been studied to analyze the physical elements of classroom(learning tools, equipment, etc.) to provide deeper understanding on their display, and spatial arrangement, as well as characteristic of a classroom. By looking at these analyzed elements with perspective to the grade, the number of students per class, the result turned out to be uninteresting. The observation that was made by this analysis was that there are more usages of multi-purpose desk in the classroom when there are only a few numbers of students. Also the observation could be made on the classroom wall-post. Each post had a tendency to have its defined area to be posted. The analysis showed that there are total of 24 corners can be created in the classroom, also it distinctly showed that the number of corners gets changed depending on the number of students in the classroom. The 24 corners including learning tools, equipment, and posts could be sorted to a minimum of 11 areas and a maximum of 22 areas depending on the educational purpose of the corners. The current layout of these corner and area will be the primary component that will be needed for the new coming classroom. For the future progress, depending on the system of education, the following needs to be done: (1) The installation of corners in the classroom (2) A small common-lounge area between two classrooms (3) A common-corner for each grade (4) Deeper research will be required to discuss the installation of a wide-educational area.

• International Journal of Naval Architecture and Ocean Engineering
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• 제4권2호
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• pp.151-161
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• 2012

The present study numerically investigates the aerodynamic characteristics of two-dimensional wings in the vicinity of the ground by solving two-dimensional steady incompressible Navier-Stokes equations with the turbulence closure model of the realizable k-${\varepsilon}$ model. Numerical simulations are performed at a wide range of the normalized ground clearance by the chord length ($0.1{\leq}h/C{\leq}1.25$) for the angles of attack ($0^{\circ}{\leq}{\alpha}{\leq}10^{\circ}$) in the prestall regime at a Reynolds number (Re) of $2{\times}10^6$ based on free stream velocity $U_{\infty}$ and the chord length. As the physical model of this study, a cambered airfoil of NACA 4406 has been selected by a performance test for various airfoils. The maximum lift-to-drag ratio is achieved at ${\alpha}=4^{\circ}$ and h / C = 0.1. Under the conditions of ${\alpha}=4^{\circ}$ and h / C = 0.1, the effect of the Reynolds number on the aerodynamic characteristics of NACA 4406 is investigated in the range of $2{\times}10^5{\leq}Re{\leq}2{\times}10^9$. As Re increases, $C_l$ and $C_d$ augments and decreases, respectively, and the lift-to-drag ratio increases linearly.

• 대한기계학회논문집B
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• 제39권4호
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• pp.325-333
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• 2015

본 연구에서는 층류 점성유동에서 원형 실린더를 기준으로 홈을 이용한 실린더의 형상변화가 유동 특성에 미치는 영향 분석을 2차원 수치 해석으로 수행하였다. 사용한 좌표계는 직교 좌표계로서 가상경계법과 표시 입자 기법을 사용하여 실린더를 구현하였다. 홈의 개수와 위치를 변수로 Re=40, 50에서 계산하였으며, 홈의 수와 위치에 의한 유동 불안정성을 해석하여 임계 레이놀즈 수를 구하였다.

• 대한기계학회논문집B
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• 제28권10호
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• pp.1139-1146
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• 2004

The effect of triangular tabs attached at the perimeter of jet nozzle on heat transfer enhancement was investigated experimentally. The modified flow structure was visualized using a smoke-wire method. Four different types of jet nozzle having 0, 4, 6 and 8 tabs were tested at jet Reynolds number Re=15,000 to investigate the effect of tabs on the variation of heat transfer rate. The local and average Nusselt numbers are increased with increasing the number of tabs. At nozzle-to-plate distance of L/D=4, the average Nusselt number was increased about 9.9% at Re=15,000 in the impingement region for the case of 8 tabs attachment. As the nozzle-to-plate distance increases, however, the heat transfer enhancement effect of triangular tabs is reduced. For the case of 4 tabs, the heat transfer enhancement is not so distinctive at L/D=8. As the protrusion depth of tabs into the jet flow increases, the heat transfer rate is also enhanced when the nozzle-to-plate distance is smaller than L/D=6.