• Solar Energy
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• v.8 no.2
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• pp.66-72
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• 1988

Natural convection in a horizontal annulus with spacers has been studied on the effects of diameter ratio and Rayleigh numbers and position of spacers by experimental method. In case of vertical spacers, the local spacer Nusselt numbers show positive values on the lower spacer, but negative values on the upper spacer. In case of horizontal spacers, the local spacer Nusselt numbers show positive values on the upward surface of spacer, but negative values on the downward surface of spacer. The mean tube Nusselt numbers and mean cylinder Nusselt numbers with vertical spacer are increased 10% and 2.1%, respectively by those of horizontal spacer.

• Journal of the Korean Solar Energy Society
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• v.27 no.4
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• pp.147-155
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• 2007

It is essential to investigate the structure and the main characteristic of Home USN (Ubiquitous Sensor Network) technologies in built ubiquitous environment while designing future residential space. For this study, three different housing types have been selected to implement ubiquitous technologies for residential space; those are regular, elderly, and single residence units. It is certain that efficiency of ubiquitous home design is improved if main components of each specific housing type are analyzed precisely in digital way and design models are prepared accordingly. Ubiquitous technology, in conclusion, has to be applied not on)r with systematical mechanism or electronic setting but in human-centered atmosphere as well, keeping with deep consideration for bio-housing service factors in eco-friendly surrounding; we call this Ubiquitous Humanism.

• Journal of the Korean Solar Energy Society
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• v.40 no.1
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• pp.35-47
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• 2020

Due to the large window area, the lighting environment of the educational space between the window and deep part of the room is not uniformly illuminated, and the phenomenon of glare is severe. For this reason, the daylight performance of DSC-BIPV windows was analyzed in order to improve the natural lighting in the educational sector. The method derives the correlation with natural lighting by measurement and simulation. Dynamic simulation confirmed that the average illuminance of the target space was higher at later than the early afternoon. The performance of natural lighting at 40% and 30% transmission of DSC has the effect of significantly reducing the amount of excess light in existing windows. Nevertheless, the actual average illuminance in all seasons corresponds to the standard illuminance of the educational facility, 300 Lux. In addition, the uniformity is also seen through the skylight illuminance ratio.

• Solar Energy
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• v.12 no.3
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• pp.21-27
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• 1992

This study is presents model testing to evalute daylighting performance in Atrium Building. There are several methods fof the prediction of Daylighting level in a Atrium Building, But they are not sufficient to estimate intreior daylight level of each different hights onleaner Atrium Building. In this study provide with making the model to estimate the environmental effect for the daylight on leaner Atrium, measuring the model in 80 variable sky condition, building direction, interior length-width ratio through the variation of floor-hight and space ratio.

• Solar Energy
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• v.20 no.4
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• pp.53-60
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• 2000

An experimental study was carried out in a cavity with upper channel and square heat surface by visualization equipment with Mach-Zehnder interferometer and laser apparatus. The visualization system consists of 2-dimensional sheet light by Argon-Ion Laser with cylindrical lens and flow picture recording system. Instant simultaneous velocity vectors at whole field were measured by 2-D PIV system(CACTUS'2000). Obtained result showed various flow patterns. Severe unsteady flow fluctuation within the cavity are remarkable and sheared mixing layer phenomena are also found at the region where inlet flow is collided with the counter-clockwise rotating main primary vortex. Photographs of Mach-Zehnder are also compared in terms of constant heat flux.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04b
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• pp.601-603
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• 2002

MRI 스캔중 촬상 대상물의 화강평면내에서의 회전은 MRI 신호에 위상오차와 불균일 표본화를 일으킨다. 따라서, 아티팩트가 포함된 MR 화상의 화질열화를 개선하기 위하여 다음과 같은 방법들을 제안한다. 우선, 미리 주어진 회전파라메타써 쌍일처 보간과 중첩 특성을 이용해서 k 공간 불균일 표본화 데이터를 수정하는 알고리즘과, 2차원 회전운동의 회전각은 이미 알려져 있고, 회전중심 위치가 미지인 경우에 대해 위상보정에 기초한 아티팩트를 보정하는 알고리즘 및 회전중심과 각도가 모두 미지인 2차원 회전운동에 대해 아티팩느를 보정하는 알고리즘을 제안한다. 이 때, 미지운동 파라메타를 예측하기 위해 찰상대상물의 경계바깥쪽에서 이상적인 MR 화상의 에너지는 최소가 되고, 활상 대상물의 회전이 존재할 때 측정된 에너지가 증가한다는 성질을 이용했다. 이러만 성질을 이용해서 시뮬레이션 화상에 적용한 결과 제안한 방법에 대한 유효성을 확인하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.11a
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• pp.114-116
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• 2016

본 논문은 human visual system(HVS)에 따른 주파수 민감도와 공간에서 다양한 특성들을 구현하기 위한 신호처리 방법을 개발하였다. 인간의 눈은 주파수 성분에 따라 민감도가 다르며 초점에서 멀수록 인지 가능한 해상도가 떨어진다. 주파수 민감도를 구현하기 위해서 본 논문은 영상 신호의 에너지 스펙트럼 모양이 contrast sensitivity function(CSF)의 모양이 되도록하여 영상 신호의 에너지를 증가시켰으며 신호 방향에 적응적인 multiband energy scaling 방법을 개발하였다. 기존의 시스템에서 능률만을 향상시키는 기존의 분석 모델과 비교하면 개발한 방법은 HVS에 좀 더 적절하고 선호되게 영상 신호를 처리 할 수 있다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.154-156
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• 2015

본 논문은 human visual system(HVS)에 따른 주파수 민감도와 공간에서 다양한 특성들을 구현하기 위한 신호처리 방법을 개발하였다. 인간의 눈은 주파수 성분에 따라 민감도가 다르며 초점에서 멀수록 인지 가능한 해상도가 떨어진다. 주파수 민감도를 구현하기 위해서 본 논문은 영상 신호의 에너지 스펙트럼 모양이 contrast sensitivity function(CSF)의 모양이 되도록하여 영상 신호의 에너지를 증가시켰으며 신호 방향에 적응적인 multiband energy scaling 방법을 개발하였다. 기존의 시스템에서 능률만을 향상시키는 기존의 분석 모델과 비교하면 개발한 방법은 HVS에 좀 더 적절하고 선호되게 영상 신호를 처리할 수 있다.

• Solar Energy
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• v.2 no.1
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• pp.1-8
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• 1982

A theoretical study by numerical method has been performed on the natural convection of an air contained in enclosures. The enclosures have rectangular cross section with one vertical wall heated and the other cooled, and with two horizontal partition plates of finite thermal conductivity. Steady two-dimensional flow was assumed. The computation was executed by means of the Implicit Alternating Direction (I.A.D) finite-difference method. Two partition plates of Aluminium whose thickness were 0.05mm was employed in computation. Isothemals, streamlines, local Nusselt numbers and mean Nusselt numbers were obtained for various Grashof numbers and aspect ratio and these results were compared with those in the case of the enclosure with two horizontal insulated plates. From the present results, the heat transfer in the case of partition plates was greater than that in the case of insulation. This study suggests a method to measure the overall heat-transfer of coefficient in double walls which supported by partition plates for insulative construction.

• Solar Energy
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• v.2 no.1
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• pp.9-16
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• 1982

The problem of transient laminar natural convection in compressible fluid in a rectangular enclosure is considered. The upper and lower boundaries of the enclosure are thermally insulating and the side boundaries are maintained at fixed temperatures. The fluid is considered to be a perfect gas with constant viscosity and thermal conductivity and the formulation differs from the boussinesq simplification in that the effects of variable density are completely retained. The motions are restricted to two dimensions. For incompressible fluid, the natural convection is driven mainly by buoyancy force. But the solutions show that for compressible fluid, the natural convection is driven by pressure and buoyancy forces and the thermally induced motion is acoustic in nature.