• 한국공간구조학회논문집
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• 제11권2호
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• pp.71-79
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• 2011

케이블 구조시스템의 경우 자기 평형 상태를 유지하기 때문에 장력이 손실된 특정 케이블을 재긴장을 하지 않으면 구조엔지니어가 요구한 하중보다 더 큰 하중이 다른 케이블에 전달되어 손상을 야기 할 수 있다. 또한, 턴버클을 이용한 재긴장 방법이 기존에 널리 적용되고 있지만 정확한 장력조절과 대구경 케이블에는 적절하지 못하고 인장재의 하중의 크기를 측정하는 것이 어렵다. 따라서 효과적으로 재긴장 할 수 있는 유압식 볼팅 접합부를 개발하고 인장력을 실시간으로 확인할 수 있는 모니터링 시스템을 적용하였다. 본 논문에서는 개발된 시스템의 현장 적용성 실험과 결과를 제시하였다.

• 한국재료학회지
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• 제12권9호
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• pp.729-734
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• 2002

Porous Al metal was produced by batch type casting process. In this foaming process, the viscosity and surface tension of molten Al as two most important factors have been investigated in the temperature range of 680-95$0^{\circ}C$ by the ring method and rotational method respectively. The experimental results showed that both the surface tension and viscosity of the melt decreased linearly with increasing temperature. Addition of Ca decreased surface tension, but increased viscosity significantly.

• 한국공간구조학회논문집
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• 제16권2호
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• pp.39-45
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• 2016

Membrane structure is a system that is stabilized by maintaining a tensile state of the membrane material that originally cannot resist the bending or pressure. Also, it is a system that allows the whole membrane structure to bear external loads caused by wind or precipitation such as snow, rain and etc. Tension relaxation phenomenon can transpire to the tension that is introduced to the fabric over time, due to the innate characteristics of the membrane material. Thus, it is important to accurately understand the size of the membrane tension after the completion of the structures, for maintenance and management purposes. The authors have proposed the principle of theoretically and indirectly measuring the tension by vibrating the membrane surface with sound waves exposures against the surface, which is compartmentalized by a rectangular boundary, and by measuring the natural frequency of the membrane surface that selectively resonates. The authors of this paper measured the tension of preexisting membrane structure for its maintenance by using the developed portable measurement equipment. Through analyzing the measurement data, the authors review the points that should be improved and the technical method for the new maintenance system of membrane tension.

• 문화기술의 융합
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• 제9권4호
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• pp.549-555
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• 2023

공용중인 고속철도의 PSC Box 교량의 긴장력 관리는 교량 성능에 있어 매우 중요한 기능으로 교량 유지관리시 세밀한 관리가 필요하다. 이에 본 연구에서는 열차(활하중) 재하시험 없이 측정한 상시처짐 결과를 이용하여 PSC Box girder 내부의 긴장력 감소 수준과 긴장력 손실에 다른 재긴장 예측 시기를 연구하고자 한다. PSC Box 거더의 긴장력 감소에 따른 재긴장 시기 예측결과, 준공 이후 약 17년 이전에서는 긴장력 감소(Jacking force loss) 곡선이 완만한 것으로 나나낫다. 그러나 17년 이후에서는 긴장력 감소 곡선이 급격하게 변화되는 것으로 나타났다. 따라서 공용연수 증가에 따라 긴장력이 감소하는 것으로 확인되었고, 구조물의 노후화가 진행될수록 긴장재의 손신을 더 급격하게 증가되는 것으로 분석되었다. 향후 공용중인 PSC Box 교량중에서 준공 이후 18년 이상 경과된 구조물의 경우 긴장재 및 주변 손상에 대한 정밀조사가 필요할 것으로 판단된다.

• Journal of Chest Surgery
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• 제9권2호
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• pp.109-116
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• 1976

The effects of atelectasis on surface activity of lung extracts were examined in rabbits. Experimental atelectasis was produced in rabbits by artificial pneumothorax and surface tension properties were measured on saline extracts of lung 24 hrs, 48 hrs, one week and four weeks after the induction of pneumothorax. The results were as follows; 1) The minimum surface tension of excised lung extracts 24 hrs after pneumothorax was significantly increased to 28.3 0.41 dynes/cm, and the stability index was significantly decreased to 0.30 from normal value of 0. 87. 2) In the group which was re-expanded 24 hours, later from pneumothorax the surface activity was returned to almost normal range 24 hrs after reexpansion of collapsed lung, 3) When the atelectasis was continued by mechanical means, the extracts of atelectatic lung showed progressive decrease in surface activity, but it was found that surface activity returned to normal level after four weeks even the presence of atelectasis. 4) These observations suggest to us that atelectasis per se does not cause an increase in surface tension of lung extracts, and even in prolonged atelectasis the re-expansion of collapsed lung may be possible when the mechanical cause of atelectasis was excluded.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.111-112
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• 2002

The influence of aerated oil on a high-speed proceeding bearing is examined by using the classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of air-oil mixture in fluid-film bearing including the live surface tension of aerated oil. Convection to the walls and mixing with supply oil and re-circulating oil are considered. The considered parameters for the study of bubbly lubrication are oil aeration level, air bubble size and shaft speed. The results show that, if the live surface tension is considered, the effect of air bubbles on the bearing load capacity is reduced due to temperature engagement comparing with that under the condition of a constant surface tension.

• 건축역사연구
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• 제14권1호
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• pp.107-122
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• 2005

The purpose of this study is to analyse Herzog & de Meuron's surface, which represents contemporary architectural trends toward surface. Semper's Bekleidung theory and the important architectural theories about surface were compared according to the conceptual opposition between representation and re-presentation, which is borrowed from Kastern Harris, and again Martin Heidegger. Representation means a sort of translation into a different medium. It doesn't preserve the material identity of what it represent. Re-presentation, however, celebrates the material employed. The tension between representation and re-presentation have activated the architectural history Contemporary architects have emphasized re-presentation at the expense of representation. This trends relate with digital technology, which demands surface or skin independent from depth or interior. Buildings that deserve to be called works of architecture invite us to attend to material in a different way Re-presenting its materials, the work of architecture reveals its being. Such revelation requires that materials work in a way that invites us to step back from our usual involvement with things. It's the poetics of re-presentation, which is emboded in the Herzog & de Meuron's architectural works.

• Korean Chemical Engineering Research
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• 제52권4호
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• pp.516-521
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• 2014

고점성이며 낮은 표면장력 매체로 구성된 기포탑에서 축방향 국부 열전달 계수와 총괄 열전달 계수에 대해 고찰하였다. 기체공탑유속(0.02~0.10 m/s), 액체 점도($0.1{\sim}0.3Pa{\cdot}s$) 그리고 액체 표면장력($66.1{\sim}72.9{\times}10^{-3}N/m$)이 국부 및 총괄 열전달 계수에 미치는 영향을 검토하였다. 열전달 영역은 기포탑 내부 열원과 기포탑 간의 열전달계로 구성하였다. 즉, 기포탑의 중앙에 수직 열원을 설치하여 내부 열원으로 하였다. 열전달 계수는 주어진 운전조건에서 열원에 제공되는 열량과 내부 열원과 기포탑 간의 온도차를 연속적으로 측정하여 결정하였다. 국부 열전달 계수는 기체공탑유속이 증가함에 따라 증가하였으나 기체 분산판으로 부터의 축방향 거리가 증가함에 따라, 액체의 표면장력이 증가함에 따라 감소하였다. 총괄 열전달 계수는 기체공탑유속이 증가함에 따라 증가하였으나 액상의 점도와 표면장력이 증가함에 따라서는 감소하였다. 총괄 열전달 계수는 기체공탑유속, 액상의 점도와 표면장력의 함수로 상관계수 0.91의 상관식을 얻을 수 있었으며 넛셀 수, 레이놀즈 수, 플란틀 수 그리고 웨버 수의 함수로 상관계수 0.92의 상관식으로 나타낼 수 있었다. $$h=2502U^{0.236}_{G}{\mu}^{-0.250}_{L}{\sigma}^{-0.028}_L$$ $$Nu=325Re^{0.180}Pr^{-0.067}We^{0.028}$$.

• KSTLE International Journal
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• 제2권2호
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• pp.103-113
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• 2001

The influence of aerated oil on high-speed journal bearing is examined by classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of air-oil mixture in fluid-film bearing. Convection to the walls and mixing with supply oil and re-circulating oil are considered. The live oil surface tension is considered as functions of temperature, API gravity and air volume ratio. With changing eccentricity ratio, it is investigated the effects of air bubbles on the performance of a high-speed plain journal bearing. Just at the moderate eccentricity ratios, even if the involved aeration levels are not so severe and the entrained air bubble sizes are not so small, it is found that the bearing load and friction farce may be changed so visibly for the high speed bearing operation.

• 한국안전학회지
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• 제28권3호
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• pp.74-79
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• 2013

As the feature of fire, it is hard for deep-seated fire to spread to the deeper site, and it also has danger for being re-ignited cause of recontacting with oxygen after being put off. Now it is ruled in the certification criteria of wetting agent used for extinguishing deep-seated fire that the criteria for surface tension is below 33[mN/m] in Korea. For figuring out how much water for fire-fighiting can permeate into combustibles, in this research, the permeating performance is analyzed by measuring the speed of permeating and transmission quantity released after that, by pouring solution whose surface tension is changed by adjusting concentration of surfactant BDG(Butyl Di Glycol) in column From this result, it is can be determined that transmission quantity becomes less and wet area goes wider as surface tension is lower, and it is also able to be analyzed as quantity of absorbed liquid and wet area is increased because fluid permeates into the core.