• Journal of The Korean Digital Architecture Interior Association
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• v.13 no.2
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• pp.35-43
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• 2013

The green building is one of biggest factors to go the goal of energy saving and environmental conservation, "reduction of energy consumption, friendly energy technology, recycling of resource, and environmental pollution reduction technology. The purpose of these green buildings realized by the energy-saving technology such as the thermal bridge breaker(or thermal bridge block). Thermal bridges are localized elements that penetrate insulated portions of building envelope that results in heat loss. The purpose of this paper is to describe the technical interactions for patents of a thermal bridge breaker(TTB) used in green building practices, and be subject to investigation to TTB in the leading countries, that is, United State, Europe Union, Japan, and Korea. As a result, there are four TTB categories(roof, wall-slab connection, opening, footing) in house or building. The TTB categories is remarkable technology that is apparatus in slab-wall joints and sealing element of opening frame in walls.

• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.483-489
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• 2017

The loss of the sulfur cathode material through dissolution of the polysulfide into electrolyte causes a significant capacity reduction of the lithium-sulfur cell during the charge-discharge reaction, thereby debilitating the electrochemical performance of the cell. We addressed this problem by using a chemical and physical approach called reduction of polysulfide dissolution through direct coating functional inorganic (graphene oxide) or organic layer (polyethylene oxide) on electrode, since the deposition of external functional layer can chemically interact with polysulfide and physically prevent the leakage of lithium polysulfide out of the electrode. Through this approach, we obtained a composite electrode for a lithium-sulfur battery (sulfur: 60%) coated with uniform and thin external functional layers where the thin external layer was coated on the electrode by solution coating and drying by a subsequent heat treatment at low temperature (${\sim}80^{\circ}C$). The external functional layer, such as inorganic or organic layer, not only alleviates the dissolution of the polysulfide electrolyte during the charging/discharging through physical layer formation, but also makes a chemical interaction between the polysulfide and the functional layer. As-formed lithium-sulfur battery exhibits stable cycling electrochemical performance during charging and discharging at a reversible capacity of 700~1187 mAh/g at 0.1 C (1 C = 1675 mA/g) for 30 cycles or more.

• The Journal of the Acoustical Society of Korea
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• v.32 no.1
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• pp.43-55
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• 2013

The window ventilation system based on the heat recovery device was developed which make air ventilation possible without opening the windows. However, mechanical and aerodynamic noises were come to pass which annoyed people in rooms. In the present study, noise of new window ventilation system was measured in both general room and anechoic chamber. Also, the noise path was detected to find cause of noise generation and vulnerable area of the device. Sound absorptive and insulation materials were applied to mitigate the noise. Finally, an alternative noise control method was suggested which can satisfy with the indoor noise standards. As a result, it was shown that the cause of noise was the low transmission loss in the ventilation system. As a result, it was shown that the main noise source of the ventilation system was the blower and the major cause of noise was the low transmission loss of the ventilation system. It is also concluded that the noise levels complies with the noise standards of 40 dBA when 2 mm rubber sheet is applied inside the ventilation system.

• Journal of Environmental Science International
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• v.30 no.2
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• pp.135-143
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• 2021

This study executed evaluation of drying characteristics based on the polymer injection rate (8%, 10% and 12%) and the drying method[NIF(near-infrared ray). According to this study analyzed VS, VS/TS, and calorific value compared with 'the auxiliary fuel standard of the thermoelectric power plant and the combined heat & power plant'. The results are as follows. In the case of NIR, the VS was slightly changed at the early stage of the material preheating period and the constant drying rate period with low moisture evaporation. But VS reduction was shown higher as moisture was dried. In the case of non-digested sludge with high VS content, the VS reduction rate by drying was shown lower than that of digested sludge. As the flocculant injection rate increased, the VS loss due th drying was found to be small. Also, the higher the flocculant injection rate was the longer the drying time. Especially, in the case of the NIR drying equipment, as the moisture content of sewage sludge decreased(moisture content 20~40%), the loss of net VS also showed a tendency to increase sharply. It is shown that the high calorific value according to the drying time of the non-digested sludge was changed from 590 kcaℓ/kg to 3,005 kcaℓ/kg and from 539 kcaℓ/kg to 2,796 kcaℓ/kg.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.71-80
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• 2015

Steel stiffener is required for reinforcing the structure of the window frame made of versatile but weak PVC material. Steel stiffener however becomes a source of greater heat loss and frequently plays a role of thermal bridge due to its high thermal conductivity. To maintain thermal resistance similar to PVC frame, steel stiffener is perforated to reduce the effective heat transfer area. To compensate the structural strength of the steel stiffener which is weakened by the perforation, the thickness is increased. Increase in thickness will also increase the thermal heat resistance. Five samples which are PVC frame, PVC frame + original steel stiffener, PVC frame + 30% perforated steel stiffener, PVC frame + 50% perforated steel stiffener, PVC frame + 65% perforated steel stiffener are modeled and simulated for 2nd moment of area and thermal resistance. Therm/window version 6.3 is used for thermal analysis. The results show that among the five samples analyzed, PVC frame + 65% perforated steel stiffener best satisfies both structural strength and thermal resistance.

• Journal of the Korean Solar Energy Society
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• v.32 no.spc3
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• pp.207-212
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• 2012

It is important to produce the high-temperature and high-pressure air for the concentrated solar power system using the combined cycle. In this paper, we designed two types of tubular receivers to heat up the compressed air and provided their preliminary experimental results for performance evaluation and further improvements. The developed receivers are in a square cavity shape surrounded by flow conduits for easy scale-up and radiation loss reduction. The two receivers were tested with 5 bar air in the KIER solar furnace and evaluated in terms of the outlet temperature and the efficiency.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.149-152
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• 2002

SrZrO3 resistive oxide barriers on Ag sheathed Bi2223 tapes prepared by the sol-gel and dip coating method were evaluated with an aid of Taguchi method and orthogonal arrays to elucidate the effects of experimental parameters, such as ratio of starting solution, amount of additives, and heat treatment temperature and time on the properties of the thin films. Six experimental parameters were selected and then Ll8(21x37) orthogonal arrays were constructed. Finally, SEM and XRD results were related to signal to noise (S/N) ratio to evaluate the optimized experimental condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.112-117
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• 2007

With the Euro-4 regulation coming into effect, the domestic car industry is forced to look for newer options to reduce NOX in the exhaust. EGR(Exhaust Gas Recirculation) Cooler is an effective method for the reduction of NOX form a diesel engine. High efficiency, low pressure loss and compactness are desirable features of an EGR Cooler. The cooling performance of EGR depends on the shape of tubes and the location of the entrance and exit. This paper reports the computational work conducted to estimate the performance of EGR cooler with three different cross section tubes and a triangular spiral tube. Three dimensional computation results show that the triangular tube is more effective than circular and rectangular tube. The most effective geometry is a triangular spiral tube with offset inlet and outlet locations.

• KIEAE Journal
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• v.5 no.1
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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.

• Journal of Korea Foundry Society
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• v.13 no.6
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• pp.563-573
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• 1993

The wear resistance of Hyper-eutectic Al-Si alloy, have recently been noticed as a new automobile material, was investigated. For the purpose of developing wear resistant Al-Si alloy, some factors which attribute to wear resistance are examined as follows; refinement of primary Si particle during solidification, and effect of refinement on wear resistance and other mechanical properties. The most effective refinement was accomplished by adding both NaF and S, and this improve wear-resistance in abrasive wear type. The wear losses of specimens cast in metal mold were ruduced to 80% of those in sand mold. T6 heat treatment increases hardness, which resulted in reduction of wear loss about $3{\sim}18%$.