• KIEAE Journal
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• 제15권2호
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• pp.61-67
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• 2015

Purpose: The balcony in the apartment is important space not only as a fire escape but also as a buffer for heat and sound insulation. However, with the legalization of balcony expansion for residential apartments in Korea in 2006, many households have eliminated the balcony space altogether to increase the inner space, often without sufficient consideration for the effects on the indoor environment. This study examined the sound insulation performance of exterior-facing windows in enclosed balconies and the changes in the indoor acoustic environment due to expansion to provide a basis for appropriate balcony expansion. The apartments for the field test were chosen where two balcony types can be compared, and the sound insulation performance for the eighteen balcony windows was measured. The windows installed were typical double window with thickness 16 mm or 22 mm. Measurements of the weighted standard sound pressure level difference showed a decrease of about 3 dB in sound insulation performance due to expansion. For common exterior noise levels of 70-85 dB(A), the indoor noise level can exceed 45 dB(A), the limit level regulated in Korea. However, it was found that the sound insulation performance of the window and the quality of the construction have more influence on indoor noise levels than balcony expansion itself.

• 한국전기전자재료학회논문지
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• 제17권3호
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• pp.348-352
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• 2004

The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and ow loss, but it needs some cooling method because heat radiation between each winding is difficult. The life of transformer is significantly dependent on the thermal behavior in windings. Many transformer designers have calculated temperature distribution and hot spot point by finite element method(FEM) to analyze winding temperature rise. In this paper, The thermal analysis of pole mount mold transformer with one body molding by duct condition is investigated and the test result of temperature rise is compared with simulation data.

• 한국전기전자재료학회논문지
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• 제19권12호
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• pp.1154-1159
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• 2006

The mold transformers have been widely used in underground substations of large building and have some advantages when compared with oil-transformer. Those advantages are low fire risk, environmental compatibility, compact size and high reliability. The mold transformer is generally known to have cooling duct between low voltage and high voltage coil. To achieve better compact structure and low loss, mold transformers made by one body molding method has been developed. Nevertheless, such kinds of transformer need better cooling method because heat radiation between each winding is still of problem. The life of transformer is significantly dependent on the thermal behavior in windings. Many designers have calculated temperature distribution in transformers and hot spot point by finite element method(FEM) to analyze winding temperature rise. In this paper, the temperature distribution analysis of 100 kVA pole mold transformer for power distribution were investigated by FEM program and the thermal analysis results were compared with temperature rise test.

• Journal of Advanced Marine Engineering and Technology
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• 제28권7호
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• pp.1123-1130
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• 2004

Numerical simulations have been carried out to investigate the effect of nozzle hole geometry on the combustion characteristics of the large diesel engine. 6S90MC-C. Spray and combustion phenomena were examined numerically using FIRE code. Wane breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation processes. Predictions on the cylinder peak pressure and NOx emission were first verified with the experimental data to confirm the reliability of numerical calculations. The comparison results showed good agreements within the range of 0.64% and 4.6% respectively. Finally, the effects of fuel spray angle and diameter on the engine performance were investigated numerically to find the optimum nozzle hole geometry considering fuel consumption, NOx emission and heat flux of the combustion chamber wall. It was concluded that the combustion gas recirculation in cylinder by changing fuel injection direction is an effective method to reduce NOx emission by about 10% with increasing fuel oil consumption, 1.4% in a large diesel engine.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.393-396
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• 2000

Spent fuel rod cutting device should cut a spent fuel rod to an optimal size in order to fast decladding operation. In this paper, for developing spent fuel rod cutting device with cutter blade, rod properties such as dimension and material of zircaloy tube and fuel pellet are investigated at first and then, various methods of existing cutting devices used commercially are investigated and their performance are analyzed and compared. This device is designed to be operated automatically via remote control system considering later use in Hot-Cell (radioactive area) and the mdularization in the structure of this device makes maintenance easy. SUS and Zircaloy-4 are selected as cut material used in the test of spent fuel rod cutting device by cutter blade. In order for constructing the high durable cutter blade, various materials are analyzed in terms of quality, shape, characteristic, and heat treatment, etc. and from these results, spent fuel rod cutting device is designed and manufactured based on the considerations of durability, round shape sustainability of rod cross-section, debris generation, and fire risk, etc.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.928-931
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• 2006

Due to their light weight, high stiffness-to-weight and strength-to-weight ratios, and potentially high resistance to environmental degradation, resulting in lower life-cycle costs, polymer composites, are increasingly being considered for use in civil infrastructure applications. Recently, an FRP deck has been installed on a state highway, located in New York State. In this study, a thermal stress analysis was conducted using finite element method to study failure mechanisms of the superstructure. This analysis evaluated small and large temperature gradient effects on the FRP deck considering lightweight of FRP deck and ply orientations at the interface between steel girders and FRP deck Finite element model was verified using the load tests of the bridge deck. Finally, the analytical results shows the possible failure mechanism of FRP deck under various temperature changes and its corresponding index is suddenly varied depending on the rapid change of temperature on the deck plate.

• 한국태양에너지학회 논문집
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• 제30권1호
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• pp.42-49
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• 2010

The IIS(Internal Insulation System) is applied in most Korean apartment buildings which are the most common type of residential buildings. Consequently, there are many cases in which the layer of insulation is disconnected by the structural components at the wall-slab and wall-wall joints in the envelope. These joints become thermal bridges where the risk of heat loss increases. It is expected that the EIFS(External Insulation and Finish System) is the solution to this problem. In this study, annual heating and cooling loads of apartment buildings with IIS and EIFS were compared using Design Builder program in order to evaluate the thermal storage effect of EIFS where the concrete thermal mass is located inside of the insulation material. As results, the apartment building with EIFS could reduce annual heating and cooling loads by 2.4% and 4.1%, respectively.

• 한국정밀공학회지
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• 제20권6호
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• pp.222-229
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• 2003

The purpose of this study is to evaluate the mechanical properties of 6061 Al foams, which were fabricated by P/M and multi-step induction heating method, and to build the database, which is needed for computer aided modeling or foam components design. Aluminium foams, consisting of solid aluminium and large quantities of porosities, is widely used in automotive, aerospace, naval as well as functional applications because of its high stiffness at very low density, high impact energy absorption, heat and fire resistance, and greater thermal stability than any organic material. In this study, 6061 Al foams were fabricated for variation of fraction of porosities (%) according to porosities (%)-final heating temperature ( $T_{a3}$) curves. Mechanical properties such as compressive strength, energy absorption capacity, and efficiency were investigated to evaluate the feasibility of foams as crash energy absorbing components. Moreover, effect of the surface skin thickness on plateau stress and strain sensitivity of the 6061 Al foams with low porosities (%) were studied.d.

• 한국공간구조학회논문집
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• 제8권2호
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• pp.55-62
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• 2008

막 구조는 형태의 다양성, 막의 가벼움과 내구성, 투광성 및 균질성 때문에 현대 건축물에 다용하게 사용되어 새로운 건축세계를 열어가고 있다. 본 논문은 대공간 건축 구조물에 주로 사용되는 유리섬유 막 재료의 역학적 특성에 대한 연구이다. 현재 주로 사용되는 건축용 막 재료의 종류에는 PVC, PVF, PVDF, PTFE, ETFE 막재들이 있다. 본 연구에서는 이러한 건축용 막재료에 대한 역학적 시험 방법을 정립하고, PTFE 코팅 유리섬유 막재에 대한 인장강도, 인열강도 및 반복하중 시험 등을 실시하여 건축용 막 재료의 역학적 특성을 분석하고자 한다.

• 한국해양공학회지
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• 제22권6호
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• pp.27-34
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• 2008

The temperature distribution in the weldment is not uniform because a weldment is locally heated. Thermal plastic deformation results from the local expansion and shrinkage by the heating and cooling of metal. Therefore, residual stresses and distortion occur in the weldment. In this study, we had conducted on the weld thermal cycle simulation that is supposed as the HAZ on SS400 steel and STS304 steel. The residual stresses that were obtained from the drawing and the weld thermal cycle simulation were estimated by X-ray diffraction. We also carried out ultrasonic test for the weld thermal cycle simulated specimens, and then conducted on nondestructive evaluation by the ultrasonic parameters obtained ultrasonic test. From the results, residual stresses of weld thermal cycle simulated specimens after the residual stress removal heat treatment are lower than that of the drawing.