• KIEAE Journal
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• 제5권1호
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• pp.27-33
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• 2005

Global efforts have made to reduce energy consumption and $CO_2$ gas emission. One of the weakest parts for energy loss through the whole building components is building envelopes. Lots of technologies to increase the thermal performance of building envelopes have been introduced in recent year. Transparent Insulation Wall(TIW) is a new technology for building insulation and has been function both solar transmittance and thermal insulation. A mathematical model of a Transparent Insulation Wall equipped with south wall was proposed in order to predict thermal performance under varying climates(summer and winter). Unsteady state heat transfer equations were set up using an energy balance equation and solved using Gauss-Seidel iteration solution procedure. The thermal performance of the TIW determined from a wall surface and air layer temperature, non-airconditioned room temperature and air conditioning load. As a result, this numerical study shows that the TIW is effective in an air conditioning load reduction. Further experimental study is required to establish complete TIW system.

• International Journal of Air-Conditioning and Refrigeration
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• 제12권2호
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• pp.97-107
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• 2004

Wall/floor intersection is important parts of a building envelope system. These intersections can be sources of thermal bridging effects and/or moisture condensation problems. This paper provides a detailed analysis of the thermal performance of wall/floor intersection. In particular, two-dimensional steady-state and transient solutions of the heat conduction within the wall/floor joint are presented. Various insulation configurations are considered to determine the magnitude of heat transfer increase due to wall/floor joint construction.

• 한국태양에너지학회 논문집
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• 제24권2호
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• pp.33-38
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• 2004

Outside wall systems we lost much energy from the dew of thermal bridge and unsuitable adiabatic construction. The air vent wall system can make reduce cooling loads from the outside wall in summer. The basic concept is connected with buoyant force by the difference of density. An external surface of a wall absorbs solar radiation, and transfers it to the air in the cavity. The warmed air gets buoyant force. So the warmed air is released through the top opening and cooler outside air replaces the space in the cavity. So because of the cavity and the openings, the cooling load reduction by natural ventilation is believed to be considerable. The purpose of this study is finding optimal length of air cavity by numerical analyses.

• 설비공학논문집
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• 제15권3호
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• pp.196-202
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• 2003

Two dimensional modeling was carried out to find the safety distance between the defrost heater and the plastic inner wall of domestic refrigerator Estimation was processed for the three cases; the estimation of plastic wall temperature (1) without any protection, (2) with an aluminum foil attached on a wall, and (3) with an aluminum shield installed between heater and wall. The former two cases are found to be dangerous during defrosting process, because the temperatures of inner wall reach above 80'C , which is the upper temperature limit of the wall material. The case with an aluminum shield is considered to be safe by maintaining the temperature of the wall in the range of 6$0^{\circ}C$ during defrosting process.

• 설비공학논문집
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• 제29권10호
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• pp.504-514
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• 2017

The insulation performance of aircaps has been recognized and various studies regarding the aircap as a solution to increased building energy consumption are being carried out. However, the aircap is not durable and therefore it cannot play the role of an independent finishing material. Accordingly, the purpose of this study is to suggest an aircap wall module with improved durability through the lamination of the aircap and verify its effectiveness by evaluating its energy saving performance for lighting and air conditioning through a full-scale testbed. The conclusions of this study are as follows. 1) The aircap wall module featuring a laminated aircap that is being proposed in this study can save lighting energy due to the permeability of the aircap in comparison to previous insulating materials. 2) The aircap wall module with a laminated aircap is effective in improving heating and air-conditioning energy saving when it is more than 15 cm-thick during summer and winter in comparison to a 5 cm-thick prefabricated panel. 3) The aircap wall module featuring a laminated aircap is effective in improving lighting and heating and air-conditioning energy saving when it is 10 cm- and 5 cm-thick during summer and winter, respectively, in comparison to a 5 cm-thick prefabricated panel.

• 설비공학논문집
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• 제29권1호
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• pp.21-28
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• 2017

Curtain-wall systems have been widely applied to buildings because of their lightweight and constructability characteristics. However, as curtain-wall systems include many building materials, vapor barriers can become damaged and condensation can occur. Due to the material properties of stone curtain-walls, the external appearance and structure of a building could be damaged and the insulating performance of the curtain-wall could be worse. Natural ventilation using an air cavity in a curtain-wall is expected to be effective for the prevention of condensation in inner walls and for the reduction of building cooling energy use in the summer. The purpose of this experimental study is to analyze the influence of a ventilated cavity on the insulating performance of a curtain-wall and the ventilated cavity depth and ratio of top opening needed to prevent condensation in a curtain-wall.

• 한국태양에너지학회 논문집
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• 제24권2호
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• pp.25-31
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• 2004

Ventilation through air vent system in a building envelope is expected to be an effective measure to release solar radiation. An external surface of a wall absorbs solar radiation and transfers it to the air in the cavity. The warmed air gets buoyant force. So when openings are provided at the top and bottom of the cavity, the warmed air is released through the top opening and cooler outside air replaces the space in the cavity. This reduces the further heat transmission into the built environment. This natural ventilation effect seems to be steady and strong. So because of the cavity and the openings, the cooling load reduction by natural ventilation is believed to be considerable.

• 설비공학논문집
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• 제23권2호
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• pp.103-110
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• 2011

A two-dimensional immiscible droplet deformation phenomena on moving wall in a channel has been investigated by using lattice Boltzmann method involving two-phase model. The dependence of the deformation of the droplet with different sizes on the contact angle and the velocity of bottom wall has studied. When the bottom wall starts to move, the deformation of the droplet occurs. For the largest bottom wall velocity, eventually, the deformation of the droplet is classified into the three patterns according to the contact angle.

• International Journal of Air-Conditioning and Refrigeration
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• 제14권3호
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• pp.102-109
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• 2006

Experimental results for heat transfer characteristics and pressure gradients of HCs refrigerants R-290, R-600a, R-1270 and HCFC refrigerant R-22 during evaporating inside horizontal double pipe heat exchangers are presented. The test sections which has one tube diameter of 12.70 mm with 0.89 mm wall thickness, another tube diameter of 9.52 mm with 0.76 mm wall thickness are used for this investigation. The local evaporating heat transfer coefficients of hydrocarbon refrigerants were higher than that of R-22. The average evaporating heat transfer coefficient increased with the increase of the mass flux, with the higher values in hydrocarbon refrigerants than R-22. Hydrocarbon refrigerants have higher pressure drop than R-22. Those results from the investigation can be used in the design of heat exchangers using hydrocarbons as the refrigerant for the air-conditioning systems.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.323-323
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• 2010

핵융합 플라즈마에서 연료 주입과 불순물 제거는 매우 중요한 과제로서 이를 해결하기 위한 방법으로 Glow Discharge Cleaning, ICRF Wall Conditioning과 같은 방법들을 이용한다. 최근 중국의 EAST 토카막 등에서 이러한 방법보다 보다 간소하고 효과적인 방법의 일환으로 수십에서 수백 kHZ의 HF 대역의 교류전원을 이용하여 플라즈마를 발생하고 이를 토카막 벽면의 Wall Conditioning에 적용하는 방법을 시도했다. 본 연구는 이러한 HF 플라즈마를 KSTAR 토카막 Wall Conditioning에 걱용하기 위한 예비 실험으로 선형 플라즈마 발생장치에 30kHZ 2kW급의 HF 파워를 이용하여 플라즈마를 발생하였다. 운전 압력에 따라 전압과 전류 특성을 파악하고 Langmuir probe를 이용하여 플라즈마 밀도와 온도들의 parameter를 측정하였다. 본 발표에서는 구체적인 플라즈마 발생장치를 소개하고 플라즈마 방전 특성과 parameter들을 보고할 예정이다.