• Nuclear Engineering and Technology
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• 제36권2호
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• pp.153-164
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• 2004

A computational fluid dynamics (CFD) analysis has been performed to investigate the turbulent flow and heat transfer in a triangular rod bundle with pitch-to-diameter ratios (P/D) of 1.06 and 1.12. Anisotropic turbulence models predicted the turbulence-driven secondary flow in a triangular subchannel and the distributions of the time mean velocity and temperature, showing a significantly improved agreement with the measurements from the linear standard $k-{\epsilon}$ model. The anisotropic turbulence models predicted the turbulence structure for a rod bundle with a large P/D fairly well, but could not predict the very high turbulent intensity of the azimuthal velocity observed in the narrow flow region (gap) for a rod bundle with a small P/D.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.619-621
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• 2003

We have presented in the paper preliminary results on physical characteristic parameters of a photopolymer LPPF 301 CP. The weak azimuthal anchoring energy (${\sim}5.0{\times}10^{-6}J/m^2$) of a photopolymer was measured by using a simple optical method. High pretilt up to $30^{\circ}$ has been achieved in the photoaligned cell by irradiating an obliquely incident UV light.

• 한국수소및신에너지학회논문집
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• 제11권3호
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• pp.127-136
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• 2000

Molecular dynamics simulations have been carried out to investigate the scattering and penetration properties of hydrogen ions with the normal incident angle to Ni (100) surface. The initial kinetic energies of hydrogen ions range from 100 to 1,600 eV. The simulation results are used to assess the applicabilities of theoretical predictions based on the binary collision approximation, and, in the high kinetic regime, theoretical results for scattering energies were shown to he a good agreement with molecular simulations. The angle dependencies on both scattering and penetration distributions were found in the longitudinal direction, but not in the azimuthal direction except for the high kinetic energy of 1,600 eV.

• Journal of Information Display
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• 제7권1호
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• pp.12-18
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• 2006

We investigated the horizontal alignment properties such as surface morphology, pretilt angle, and polar and azimuthal anchoring energy of organic alignment material-coated surface treated by ion beam. In this investigation the energy and incident angle of ion beam were changed. We also fabricated an in-plane switching (IPS) cell by ion beam alignment. The results showed similar voltage-transmittance characteristics to those of a rubbed cell and better dark state.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.531-533
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• 2007

A new method is developed for the measurement of twist angles of LC molecules in an LC panel with angular resolution of 0.01degree, which allows measurement of LC panels with small twist angles. The method is based on the analysis of the change in polarization state of a light beam as it passes through the LC panel in test is rotated in-plane. Compared to other traditional method, including the analysis of transmittance change, our method is more sensitive and more precise. This method allows accurate determination of anchoring energy and close analysis of the rubbing process in the fabrication of IPS mode LC panels.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.480-484
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• 2001

본 연구에서는 실제 풍력 자원 측정용 Pole에 설치된 풍속계가 mast에 의한 후류와 풍속계 설치시 기울어짐에 의해 풍속 data가 어떠한 영향을 받는가에 대하여 고찰하였다. 먼저 mast은 직경 4", 6" Pipe에 대하여 각각 실험하였고, 측정 mast의 방위각은 풍속에 평행한 방향을 $0^{\circ}$ 로 정하고 측정 mast 중심으로부터 $0^{\circ}{\sim}20^{\circ}$ 까지 $5^{\circ}$ 간격으로 측정하였다. 이 연구를 통해 실제 일정 두께를 갖는 mast에 설치되어 있는 풍속계에서의 풍속이 풍향에 대한 boom의 위치와 기울어짐에 따라 영향이 있음을 확인할 수 있었고, mast의 직경에 대한 영향도 크게 있음을 확인할 수 있었다. 따라서, 본 연구의 결과를 이용하여 향후의 풍력자원 자료 측정설비의 설치상의 정확도 검증이나 혹은 측정된 자료의 보정등에도 광범위하게 이용될 수 있을 것이다.

• 신재생에너지
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• 제4권3호
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• pp.36-44
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• 2008

This paper discusses about the mathematical modelling of a new conceptual shape of horizontal axis wind turbine. The geometrical characteristic of wind turbine is studied for the variation of azimuthal angles and elevation angles. The projecting trajectories of Cuban-8 blade due to rotation are analyzed on the each plane in the Cartesian coordinate system. Trajectories show several interesting graphical patterns since the geometrical shape is complicated with the rotational motion of two twisted circumferential blades with elevation angles.

• 한국응용과학기술학회지
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• 제16권1호
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• pp.15-20
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• 1999

Photo-crosslinkable polyimide(PI) which contains CF3 moiety was synthesized. Polarized UV light transformed ketone group of PI to hydroxyl group, which was confirmed by IR and UV-visible spectroscopy. We investigated the dichroic UV-absorption before and after photo-reaction with linearly polarized light. In particular we have attempted to clarify the relationship between the anisotropy of surface region and surface azimuthal anchoring energy and knew that the anchoring energy of photo-alignment PI is comparable with that of mechanical rubbing.

• 설비공학논문집
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• 제14권11호
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• pp.972-980
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• 2002

This work is aimed at estimating the effects of various factors on the energy consumption of Korean-style apartment houses using TRNSYS. The factors considered here include the nominal size of floor area, type of remodeling, azimuth, sidewall insulation, and window type. Based on some assumptions, an actual apartment house is simplified into a model that is used for thermal load calculations. The simplified model is validated by showing a good agreement with the actual one in the predicted result. Remodeling balconies into unconditioned buffer spaces yields a favorable thermal performance in comparison with the original type regardless of the nominal size. Incorporating balconies into a conditioned indoor space leads to sharp increases in thermal loads, which must be avoided in view of energy conservation as well as structural problem. A quantitative assessment on the azimuthal effect indicates that the heating energy can be saved up to 16％ by taking the south or southeast direction. Reduction in the heating load with enhancing the sidewall insulation is gradual, so that a cost-effectiveness analysis may be needed when amending the regulations concerned. Glazing appears to significantly affect the heat transfer through window. A typical case illustrates that the heating load is decreased about 25％ by simply adopting triple glazing instead of double glazing.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.95-101
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• 1996

In this paper, the steady 2-dimensional model for a long horizontal line with different end temperatures undergoing natural convection at very high Rayleigh number is proposed to numerically investigate the heat transfer and flow characteristics. The dimensionless governing equations are solved by using SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm which is developed using control volumes and staggered grids. The numerical results are verified by comparison with the operating PWR test data. The analysis focuses on the effects of variation of the heat transfer rates at the pipe surface, the thermal conductivities of the pipe material and the thickness of the pipe wall on the thermal stratification. The results show that the heat transfer rate at the pipe surface is the controlling parameter. A significant reduction and disappearance of thermal stratification phenomenon is observed at the Biot number of 5.0$\times$10$^{-2}$. The results also show that the increment of the thermal conductivity and thickness of the wall weakens the thermal stratification and somewhat reduces azimuthal temperature gradient in the pipe wall. Those effects are however minor, when compared with those due to the variation of the heat transfer rates at the surface of the pipe wall.