• Structural Engineering and Mechanics
• /
• 제34권2호
• /
• pp.189-211
• /
• 2010

The behaviour of a reinforced concrete tension member is governed by the contribution of concrete between cracks, tension stiffening effect. Under highly repeated loading, this contribution is progressively reduced and the member response approximates that given by the fully cracked member. When focusing on the unloaded state, experiments show deformations larger than those of the naked reinforcement. This has been referred to as negative tension stiffening and is due to the fact that concrete carries compressive stresses along the crack spacing, even thought the tie is subjected to an external tensile force. In this paper a cycle-dependent approach is presented to reproduce the behaviour of the axially loaded tension member, paying attention to the negative tension stiffening contribution. The interaction of cyclic bond degradation and time-dependent effects of concrete is investigated. Finally, some practical diagrams are given to account for the negative tension stiffening effect in reinforced concrete elements.

• 가정과삶의질연구
• /
• 제16권4호
• /
• pp.83-83
• /
• 1998

The purpose of this study is to investigate interpersonal support, tension in lifechanges & satisfaction. The selected sample is composed of 387 housewives in ChongJoo city. SAS pc program was used for the statistical analysis of the data. Data was analyzed by frequency, F-test, percentage, mean, Duncan's Multiple Range Test, Pearson's correlation coefficient, Regression Analysis. Major findings as follows: 1)At wedding & funeral ceremony, kin networks of her parents & parents-in law side were variables to have influence on tension in life changes. And the number of social organization participated were a variable to have influence on the satisfaction. The age of couple, education of couple, duration of marriage, income, family lifecycle, the number of children, pattern of family were variables to influence tension in life changes, but were not variables to influence on the satisfaction. 2) At usual or wedding & funeral ceremony, kin networks of her parents side were variables to influence on instrumental & companionship support. And the number of friends was a variable to influence on companionship & informational support. The number of neighbors was a variable to influence on instrumental, companionship & informational support. The number of social organization participated was a variable to influence on companionship & emotional support. The age of couple, education of couple,income, duration of marriage, family life cycle, number of children, family size, family type were variables to influence on interpersonal support. 3)The relationship between tension and satisfaction in life changes was negative, and between instrumental support and satisfaction was negative also. But between companionship support and satisfaction was positive relationship and between tension of personal &social life and instrumental support was positive relationship. The relationship between tension of marriage life and companionship support was negative and between tension of family life and information support was negative relationships. The received companionship support was lower tension in life changes than not received it. But the received instrumental support was higher tension of personal & social life. The received companionship & informational support was higher satisfaction than not received them. But the received instrumental support was lower satisfaction than not received it. 4) Instrumental & companionship support, at usual kin network of her parents in taw side, at wedding & funeral ceremony kin network of her parents side,were variables to influence on tension in life changes. Instrumental, companionship& informational support, at wedding & funeral ceremony kin network of her parents side, were variables to influence on the satisfaction

• The Korean Journal of Physiology and Pharmacology
• /
• 제1권6호
• /
• pp.707-716
• /
• 1997

Recent reports revealed that the $Na^+-Ca^{2+}$ exchangers and feet structures of sarcoplasmic reticulum(SR) are located in close vicinity in the specific compartment. Therefore, we investigated the possibility that the $Na^+-Ca^{2+}$ exchanger may decrease the tension development by transporting the $Ca^{2+}$ out of the cell right after it released from SR, on the basis of this anatomical proximity. We exammined the negative force-frequency relationship of the developed tension in the electrically field stimulated left atria of postnatal developing rat(1, 3 day, 1 week and 4 week old after birth). Cyclopiazonic $acid(3{\times}10^{-5}\;M)$ treatment decreased the developed tension further according to postnatal age. $Monensin(3{\times}10^{-6}\;M)$ treatment did not increase the maximal tension in 4 week-old rat, preserving negative staircase, while the negative staircase in the younger rat were flattened. $Ca^{2+}$ depletion in the buffer elicited more suppression of the maximal tension according to the frequency in all groups except the 4 week-old group. The % decrease of the maximal developed tension of 4 week-old group at 1 Hz to that of 0.1 Hz after $Na^+$ and $Ca^{2+}$ depletion was only a half of those of the yonger groups. Taken together, it is concluded that the $Na^+-Ca^{2+}$ exchange transports more $Ca^{2+}$ released from SR out of the cell in proportion to the frequency, and this is responsible for the negative staircase effect of the rat heart.

• Fibers and Polymers
• /
• 제3권2호
• /
• pp.80-84
• /
• 2002

Tension control is an important factor in producing high quality knitted products and in maintaining good processing condition. Yarn tension during knitting is subject to be affected from many elements of the machine and process parameters. Several factors including yam feeding speed, feeding angle, and needle gauge that are considered to influence on the tension variation were investigated. Yam feeding speed did not show high contribution to the tension variation but feeding angle of yam did show high correlation with the tension. No or negative correlation of the tension with needle gauge was found from the results. In order to keep well-determined process condition in the knitting manufacturing, it is strongly suggested that all knitting elements and parameters should be in the integrated control circumstance.

• 한국해양공학회지
• /
• 제4권2호
• /
• pp.185-185
• /
• 1990

• 한국전산구조공학회논문집
• /
• 제30권4호
• /
• pp.275-282
• /
• 2017

본 논문에서는 변형에 의해 유발된 패턴변화(pattern transformation)에 기반하여 압축(compression)과 인장(tension) 하중 모두에서 음의 포아송 비(negative poisson's ratio)를 나타내는 다공성(porous) 구조를 제안한다. 기존에 개발된 원형 구멍을 이용한 구조는 연결선(ligament)의 회전 모멘트 부족으로 인해 인장 시 양의 포아송 비를 나타내는 한계점이 있었으며, 타원형 구멍을 이용한 구조는 응력집중 현상으로 인하여 내구성(durability)이 약한 문제점이 있었다. 이에 본 연구에서는 휘어진 연결선의 배열을 통하여 인장하중 하에서의 회전 모멘트를 증가시키는 동시에 응력집중 현상을 완화하고 변형에너지(strain energy)를 구조물 전반에서 고르게 흡수하도록 설계하였다. 이를 통해 10%의 공칭 변형률(nominal strain) 범위 내의 압축과 인장 모두에서 음의 포아송 비를 가지며, 기존 모델에 비하여 강성(stiffness)과 내구성이 개선된 구조를 개발하였다. 비선형 유한요소해석을 통하여 기존 타원형 구멍 모델과의 비교를 수행하였으며 제안된 모델이 구조의 강성과 내구성 측면에서 현저히 개선됨을 확인하였다.

• 한국해양공학회지
• /
• 제5권1호
• /
• pp.16-24
• /
• 1991

This paper presents a method of the reliability analysis for a tension leg platform(TLP)in severe storm waves by using the first passage concept of the random tensile stress in the tendons. In the present method, two failure conditions are considered ;i.e., the exceedance of the ultimate tensile capacity and the occurrence of the negative tension. In order to consider the correlation effects between the failure events for each corner resulted from the rupture of all tencons at one corner, a new system limit state for a rectangular shaped TLP is developed, which is defined in terms of the TLP motions in the vertical plane ;i.e., heave, roll, and pitch. To illustrate the validity of the present method, the numerical analysis is carried out for two TLP's with different structural dimensions. Then, the results are compared with those by other methods.

• 대한조선학회논문집
• /
• 제29권4호
• /
• pp.146-151
• /
• 1992

이 논문에서는 스내핑 케이블(Snapping Cable)의 극단 인장력(Extreme Tension)이 연구되어지고 해석기법으로 클리핑-오프 모델(Clipping-off Model)을 이용하여 매개변수 연구(Parameter Study)가 수행되었다. 이 매개변수 연구에 의한 주어진 케이블의 초기 클리핑 발생 주파수 예측은 거친 해상에서 큰 동인장력(Large Dynamic Tension)이 발생되어 전체인장력(Total tension) 이 음의 값이 되는 스내핑현상이 일어날 수 있는 케이블의 동적 거동을 예견하기 위한 유용한 지침으로서 사용될 수 있을 것이다.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
• /
• pp.757-762
• /
• 2002

Many reports have been shown that the buoyancy, electromagnetic force, surface tension, and gas shear stress are the driving forces of weld pool circulation in arc welding. Among them, the surface tension of molten metal plays an important role in the flow in weld pool, which are clarified by the specially designed experiments with small particles as well as the numerical simulations. The surface tension is also related to the penetration in arc welding. Therefore, a quantitative evaluation of surface tension is demanded for the development of materials and arc process control. However, there are few available data published on the surface tension of molten metals, since it depends on the temperature and the composition of materials. In this study, a new method was proposed for the evaluation of surface tension and its temperature dependence, in which it is evaluated by the equilibrium condition of acting forces under a given surface geometry, especially back surface. When this method was applied to the water pool and to the back surface of molten pool in the stationary gas tungsten arc welding of thin plate, following results were obtained. In the evaluation of surface tension of water, it was shown that the back surface geometry was very sensitive to the evaluation of surface tension and the evaluated value coincided with the surface tension of water. In the measurement of molten pool in the stationary gas tungsten arc welding, it was also shown that the comparison between the surface tension and temperature distribution across the back surface gave the temperature dependent surface tension. Applying this method to the mild steel and stainless steel plates, the surface tension with negative gradient for temperature is obtained. The evaluated values are well matched with ones in the published papers.

• 한국자동차공학회논문집
• /
• 제10권1호
• /
• pp.255-264
• /
• 2002

In this paper, the power transmitting mechanism for negative torque of the metal V-belt (MVB) CVT were investigated by theoretically analyzing variation of band tension, block compression forces for each of the primary and secondary pulleys. An experimental study was performed to investigate the speed ratio - thrust characteristics for negative torque. The experimental results are in good acoordance with the theoretical results. CVT line pressure control logic was suggested for negative torque based the speed radio - negative torque - thrust characteristics and the thrust ratio curves. The results of this study can be used as basic design materials for developing the CVT control system for negative torque.