• Computers and Concrete
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• 제6권1호
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• pp.59-78
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• 2009

Reliability analysis for a proposed limit state bridge design code is performed. In order to introduce reliability concept to design code, the proposed live load model is based on truck weight survey. Test data of domestic material strengths are collected to model statistical properties of member strengths. Sample RC and PSC girder sections are designed following the safety factor format of the proposed code and compared with the current design practice. Reliability indexes are calculated and examined for material and member resistance factor formats and sample calibrations of safety factors are presented. It is concluded that the proposed code provides reasonable level of reliability compared to the international design standards.

• 한국지반신소재학회논문집
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• 제6권4호
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• pp.29-37
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• 2007

시공손상계수는 보강토 옹벽에 사용하는 지오그리드 보강재의 설계 강도 산정에 필요한 중요한 계수로서 실제 조건을 모사한 현장시험을 통해 구하고 있다. 하지만 지오그리드의 시공 중 발생하는 손상은 지오그리드의 재질, 단위면적당 중량, 뒤채움의 시공방법, 뒤채움의 입도에 따라 달라지며 현장시험을 통해 다양한 영향인자를 고려한 시공손상계수값을 도출하는데는 많은 시간과 비용이 소요된다. 본 연구에서는 시공손상에 영향을 미치는 인자들을 분석하고 뒤채움에 포함된 최대입경만을 이용하여 지오그리드 보강재의 시공손상계수를 산정하는 경험적 방법을 제시하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.281-281
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• 2009

Electrical analysis of red, green and blue (RGB) organic light emitting diode (OLED), which were measured at various temperatures from 230K to 370K by steps of 20K, were investigated using current-voltage(I-V) characteristics. Ideality factor and series resistance were obtained from the thermionic emission theory. Experimental results showed that the ideality factors were 2.12 for red, 3.80 for green, and 6.03 for blue OLED at 290K, respectively. The series resistance were 1960, 2190, 2630$\Omega$ for red, green and blue OLED at the same temperature. It was found that the OLED ideality factors were much higher than near unity for well-behaved silicon diodes, because of the organic material and multi-layer fabrication diode. In addition, the series resistance was near 2k$\Omega$ range. More researches are required to reduce both ideality factors and series resistance to increase the efficiency of OLEDs.

• Architectural research
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• 제14권3호
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• pp.93-98
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• 2012

The objective of the study is to analyze the relative performance of factors affecting indoor air quality in multi-residential buildings in Korea. A study of the factors affecting indoor air quality is essential for establishing indoor air quality management strategies effectively. To observe the indoor air quality response following a modification of a given parameter, a sensitivity analysis was performed. The factors examined for the analysis include; wall/ceiling paper, adhesive for wall/ceiling paper, floor material, adhesive for floor material, and ventilation rate. The Experimental Design which identifies main effects among the design parameters with a few experiments was used to decrease the number of experiments. The simulation for indoor air quality was undertaken using a validated equation. Then, ANOVA(Analysis of Variance) was performed to evaluate the relative importance of each parameter affecting the indoor air quality. The result of the study indicates that the indoor air quality may be influenced most by adhesive for wall/ceiling paper, followed by ventilation rate and adhesive for floor material.

• Transactions on Electrical and Electronic Materials
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• 제18권3호
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• pp.151-154
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• 2017

In this article, we investigated the various influencing factors that degraded the lifetime of suspension insulators in 154 kV transmission lines, and showed the possible solutions to avoid such breakdowns. With respect to achieve safety, reliability and aesthetical considerations, the characteristics of transmission and distribution network power cables should be improved. Suspension insulators are particularly important to study, as they have developed to be the main component of transmission lines due to their ability to withstand the electrical conductivity of high-voltage power transmission. Suspension insulators are mostly made from glass, rubber and ceramic material due to their high resistivity. In Korea, porcelain suspension insulators are typically used in the transmission line system, as they are cheaper and more flexible compared to other types of insulators. This is effective from preventing very high and steep lightening impulse voltages from causing the breakdown of suspension insulators used in power lines. Other influential factors affect the lifetime of suspension insulators that we studied include temperature, water moisture, contamination, mechanical vibration and electrical stress.

• 한국농촌건축학회논문집
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• 제9권2호
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• pp.57-66
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• 2007

The purpose of this study is to find out the characteristics of physical landscape planning and design elements in buildings on the street. This study has been conducted on the 86 buildings in Yeon-dong, Jeju city. The results of this study are as follows : In the primary design factors, the general type accounts for the highest percentage of 83.7% for the horizontal shape and also the highest of 46.4% for the vertical. For the roof, the flat roof accounts for the highest of 51.1%. In the secondary design factors, the general type's share is 43.1% for the faced type and the repetition pattern's is the highest of 50% for the faced pattern. For the outer wall material in the tertiary design factors, dryvit system accounts for 34.9%, tile 31.4%, while the cases using natural materials which reflect the regional characteristics such as woods, rocks and so on have 22%. For the roof material, the financial-friendly asphalt shingle which accounts for 76.2% has turned out to be most preferred.

• 한국전기전자재료학회논문지
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• 제13권10호
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• pp.812-816
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• 2000

It is very important to understand the correlation of between inter dielectric(ILD) CMP process and various facility factors supplied to equipment to equipment system. In this paper, the correlation between the various facility factors supplied to CMP equipment system and ILD-CMP process was studied. To prevent the partial over-polishing(edge hot-spot) generated in the wafer edge area during polishing, we analyze various facilities supplied at supply system. With facility shortage of D.I water(DIW) pressure, we introduced an adding purified $N_2$(P$N_2$)gas in polishing head cleaning station for increasing a cleaning effect. DIW pressure and P$N_2$gas factors were not related with removal rate, but edge hot-spot of patterned wafer had a serious relation. We estimated two factors (DIW pressure and P$N_2$gas) for the improvement of CMP process. Especially, we obtained a uniform planarity in patterned wafer and prohibited more than 90% wafer edge over-polishing. In this study, we acknowledged that facility factors supplied to equipment system played an important role in ILD-CMP process.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.165-170
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• 2001

The main purpose of this study is to generate a fine copper oxide powder of high purity, with a compact structure and a uniform particle size by a spray pyrolysis process. The raw material is a waste copper chloride solution formed in the manufacturing process of Print Circuit Board (PCB). This study also examines the influences of various factors on the properties of the generated powder. These factors include the reaction temperature, the inflow speed of the raw material solution, the inflow speed of the air, the size of the nozzle tip, and the concentration of the raw material solution. It is discovered that, as the reaction temperature increases from 80$0^{\circ}C$ to 100$0^{\circ}C$ , the particle size of the generated powder increases accordingly, and that the structure of the powder becomes much more compact. When the reaction temperature is 100$0^{\circ}C$, the particle size of the generated powder increases as the concentration of copper in the raw material solution increases to 40g/l, decreases as the concentration increases up to 120g/l, and increases again as the concentration reaches 200g/1. In the case of a lower concentration of the raw material solution, the generated powder appears largely in the form of CuO. As the concentration increases, however, the powder appears largely in the form of CuCl. When the concentration of copper in the raw material solution is 120g/1, the particle size of the generated powder increases as the inflow speed of the raw material solution increases. When the concentration of copper in the raw material solution is 120g/1, there is no evident change in the particle size of the generated powder as the size of the nozzle tip and the air pressure increases. When the concentration is 40g/1, however, the particle size keeps increasing until the air pressure increases to 0.5kg/$\textrm{cm}^2$, but decreases remarkably as the air pressure exceeds 0.5kg/$\textrm{cm}^2$.

• Tribology and Lubricants
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• 제13권4호
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• pp.71-78
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• 1997

Wear is affected by numerous factors-contact load, sliding velocity and distance, friction coefficient, material properties and environmental conditions. Among these wear factors, surface hardness is one of very important factors to determine wear. But surface hardness is varied by work hardening during repeated sliding contact. In this reason wear rate is increased or decreased with varying surface hardness, and transition of wear mechanism is happened. In this study, the surface hardening by accumulating residual stress was analyzed by considering the repeated sliding Hertzian contact model. The results showed that surface hardness was increased with increasing contact load, friction coefficient and contact number. And the depth of hardening layer, plastic layer and elastic layer depended upon contact load and number, but they didn't depend upon friction coefficient. The predicted surface hardness was about 1.5-1.8 times as hard as the material.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.777-783
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• 2006

The coarse grained materials are used in various construction field such as express way back fill, Dam etc. Especially, for dam construction, a huge mount of rock fill materials are needed, so around domestic stony mountains are generally developed to produce materials. Not an accurate theory, but design criteria is based on empirical factors that were constructed in advance for design of dam especially Concrete Face Rockfill Dam(CFRD). Considering the post facts, the modified design criteria are essential in the future with more theoretical and experimental ways. In this study, large scale direct shear tests are performed with various relative density conditions on coarse grained material of Yecheon area to compare test results and general CFRD design factors.