• 한국구조물진단유지관리공학회 논문집
• /
• 제16권5호
• /
• pp.88-97
• /
• 2012

본 연구에서는 비내진 교각의 내진성능과 휨-전단 거동을 파악하고자 형상비 4.5인 정사각형의 중실 및 중공단면 철근콘크리트 교각실험체를 제작하여 일정한 축력하에서 변위비 등급을 증가시켜 가면서 횡하중을 가력하는 실험을 수행하였다. 본 연구는 철근콘크리트 교각의 한정연성 내진설계를 위한 실험적 기초자료의 제공과 함께 성능단계별 교각성능 및 손상평가를 위한 정량적 수치와 경향을 제공하기 위한 것이며, 파괴거동, 극한변위, 극한드리프트비율, 변위연성도, 응답수정계수, 등가점성감쇠비, 잔류변형지수, 유효강성, 철근 변형률 등의 주요 내진성능 인자들에 대한 분석결과와 비선형 해석 결과를 나타내었다.

• 한국화재소방학회논문지
• /
• 제24권2호
• /
• pp.44-51
• /
• 2010

본 연구의 목적은 성능적 내화설계를 기반으로 한 CFT 구조의 내화성능 설계기술 개발을 최종목표로 CFT 구조의 실증적 실험을 통한 내화성능을 도출하고 내부 콘크리트 압축강도와 하중비를 변수로 하여 수축량과 시험체 내부 온도를 측정하여 내화성능을 도출하여 성능설계를 위한 기초 자료로 활용하고자 하는데 있다. KS F 2257-1과 7의 기준에 따라 CFT 각형 기둥에 24MPa, 40MPa, 하중비 0.9, 0.6, 0.2를 재하하여 내화성능기준에 따른 결과 하중비 변화는 24MPa의 경우 하중비가 0.3 감소시 약 73분의 내화성능 향상효과가 있는 것으로 나타났다. 40MPa은 하중비 0.6, 0.2의 경우 내화성능시간은 31분, 180분으로 나타났다. 시험체 내부 콘크리트 강도 변화에 따른 내화성능평가 결과 강도가 증가할수록 내화성능은 감소하는 것으로 나타났다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
• /
• pp.257-260
• /
• 2002

This study is intended is to analyze the blocking performance with variation of the gap of bar and kinds of metal lath for construction joint when placing concrete. According to the results, passing ratio of concrete increases with increase of vibrating time. In the case of W/C 50%, when blocking concrete with bar of D10 and D20 which the gap of bar is below 200mm, or metal lath, passing ratio of concrete is below 10%, so blocking performance is favorable. In the case of W/B 30%, while concrete does not flow out without vibration at slump 21mm, concrete flows out at some degree before vibration at slump flow 65mm and then, as 5 seconds passes after first vibration, final passing ratio shows about 85~90%. When blocking concrete by bar D10 of the gap 20mm, bar D20 of the gap 10mm and metal lath, it is thought that concrete can be blocked effectively because final passing ratio is below 10%.

• 한국자동차공학회논문집
• /
• 제2권2호
• /
• pp.117-123
• /
• 1994

This paper describes the effect of air assisted fuel injection system(AAI) using compressed air to improve the performance of lean combustion engine. AAI is designed to promote fuel atomization and intake flow. In order to investigate the performance of engine with AAl, experiments are conducted varying the engine revolution speed, lean air-fuel ratio and intake manifold pressure. Compared with the original engine, the performance of the engine with MI is improved as the air-fuel mixture becomes leaner or the engine load becomes lower. The descreasing rate of BSFC is propotional to the relative air-fuel ratio and the lean misfire limit extended more than 0.2 relative airfuel ratio.

• 한국벤처창업학회:학술대회논문집
• /
• 한국벤처창업학회 2006년도 추계학술발표회
• /
• pp.61-85
• /
• 2006

The Purpose of this study is to prove empirically the relationship between ventures' technology valuation and performance, while considering the uniqueness of Korean firms. We use technology valuation index, marketability valuation index, business valuation index as ex-ante independent variables, use firm's performance(sales, asset, operating income ratio, net income ratio etc) as ex-post dependent variables. Parametric analysis such as Paired T-test, ANOVA are applied in this paper. The results of Empirical analysis is summarized as follows. Firstly, operating income ratio and net income ratio are different in portfolios classified by technology valuation index. Secondly, the growth rate of operating income is different in portfolios classified by technology valuation index. Finally, this study has shown that technology valuation index has possibility which it use the predictive variables of ventures' performances.

• 한국기계가공학회지
• /
• 제8권4호
• /
• pp.83-89
• /
• 2009

This study investigates two-phase cooling system of close-loop by using FC-72 and PCM(Phase change material). The cooling system consists of evaporator, cold plate, micro pump, and condenser. The heat input on the performance of evaporator is appreciated by visualizing the boiling on the evaporator. The heat performance of cooling system is investigated to determine the effects of volume fill ratio change at working fluid, pump flow rate change, and volume fill ratio change at PCM in cold plate. Experimental results show the ideal condition when the volume ratio of working fluid, the pump flowing, and the volume ratio of PCM are 60%, 6ml/min, and 60% respectively.

• International Journal of Fluid Machinery and Systems
• /
• 제10권1호
• /
• pp.9-18
• /
• 2017

Numerical simulation is carried out for flow characteristics in a plenum fan and the influence of the diameter ratio of the rotating vaneless diffuser on the performance of plenum fan is analyzed. The diameter ratio of the rotating vaneless diffuser employed is from 1.03 to 1.3. The research results show that the rotating vaneless diffuser is able to enhance the performance of plenum fan. It is found that there is significant improvement in static pressure and efficiency at the diameter ratio of 1.05 at high flow coefficients, while the optimal diameter ratio is 1.2 at rated and low flow coefficient.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.2916-2921
• /
• 2008

This paper presents the performance and characteristics of small spark-ignited small 2-stroke engine. A single cylinder, two-stroke, air cooled 23cc SI engine for brush-cutter was used in this study. For the performance of the engine, rpm, torque, fuel consumption and lubricate oil consumption were measured, and also HC, CO, NOx emissions and excess air ratio according to throat open ratio under two lubrication method were measured and analyzed. The results showed that maximum of engine rpm is nearly same in both methods and also, torque, power is similar. exhaust emissions tend to decrease with throat open ratio.

• 지식경영연구
• /
• 제4권1호
• /
• pp.21-33
• /
• 2003

The Purpose of this study is to prove empirically the relationship between technology valuation and performance in Ventures, while considering the uniqueness of Korean firms. We use technology score, marketability score, business attractiveness score as ex-ante independent variables, use firm's performance(sales, asset, operating income ratio, net income ratio etc) as ex-post dependent variables. Parametric analysis such as Paired T-test, ANOVA are applied in this paper. The results of Empirical analysis is summarized as follows. Firstly, operating income ratio and net income ratio are different in portfolios classified by technology score. Secondly, the growth rate of operating income is different in portfolios classified by technology score. Finally, this study has shown that technology score has possibility which it use the predictive variables of firm performances.

• 한국유체기계학회 논문집
• /
• 제11권5호
• /
• pp.22-29
• /
• 2008

This study is performed to understand the effect of the variation in the passage area of a two-dimensional impeller on its performance characteristics. We observe the results with changing the area ratio of inlet to outlet about $1{\sim}2.8$. A comparison between the experimental and numerical results was performed for the same configuration in order to verify the reliability of the CFD code. Overall characteristics in the passages of impeller were analyzed in detail including streamline, Mach number, pressure and polytropic efficiency distribution. When the passage area ratio exceeds 2, the pressure ratio is high. An area ratio of 2.3 showed the highest efficiency. The results will be used as useful reference data to establish the design concept of two-dimensional impeller and to improve its performance.