• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2008년도 추계 학술논문 발표대회
• /
• pp.235-239
• /
• 2008

Cable systems are a construction of elements carrying only tension and no compression or bending in membrane structure. Tensile membrane structures are most often used as roofs as they can economically and attractively span large distances. But cable systems have weaknesses to vibration by earthquake, wind and vehicle loads. Damage detection of cable systems by using existing safety diagnosis is difficult to detect the characteristic change of overall structural action. If cable snaps are occurred to cable release and tear in tension structures, these are set up a vibration. So, we used piezo-electric materials, and The principle of operation of a piezoelectric sensor is that a physical dimension, transformed into a force, acts on two opposing faces of the sensing element. In this study, the development on test method of cable system is proposed and tested by tensile strength using piezo-electric materials.

• Geomechanics and Engineering
• /
• 제2권4호
• /
• pp.281-302
• /
• 2010

An extended model for the response of a rigid footing on a reinforced foundation bed on super soft soil is proposed by incorporating the rough membrane element into the granular bed. The super soft soil, the granular bed and the reinforcement are modeled as non-linear Winkler springs, non-linear Pasternak layer and rough membrane respectively. The hyperbolic stress-displacement response of the super soft soil and the hyperbolic shear stress-shear strain response of the granular fill are considered. The finite deformation theory is used since large settlements are expected to develop due to deformation of the super-soft soil. Parametric studies quantify the effect of each parameter on the stress-settlement response of the reinforced foundation bed, the settlement and tension profiles.

• Neonatal Medicine
• /
• 제28권1호
• /
• pp.1-6
• /
• 2021

Persistent pulmonary hypertension of the newborn (PPHN) is a consequence of the failure of a decrease in the elevated pulmonary vascular resistance after birth. Pulmonary vasodilators, including inhaled nitric oxide (iNO), have been the mainstream of targeted therapy for PPHN, but no drugs have been proven to be effective in preterm infants with PPHN. The fetus remains hemodynamically stable despite lower arterial oxygen tension and pulmonary blood flow as compared to full-term newborns. This adaptation is due to the lower oxygen requirement and high oxygen-carrying capacity of fetal circulation. The immature lungs of preterm infants are more vulnerable to reactive oxygen species, and the response of pulmonary vascular dilatation to blood oxygen tension is blunted in preterm infants. Recently, iNO has been reported to be effective in a selected group of preterm infants, such as those with prolonged preterm rupture of membrane-oligohydramnios-pulmonary hypoplasia sequence. PPHN in preterm infants, along with maximum supportive treatment based on fetal physiology and meticulous assessment of cardiovascular function, is in dire need of new treatment guidelines, including optimal dosing strategies for pulmonary vasodilators.

• 한국공간구조학회논문집
• /
• 제14권4호
• /
• pp.55-64
• /
• 2014

In this study, Intersecting Tensegrity System that is integrated solid compression members with tension members was presented. This system is set up by connecting upper and lower compression members of pyramid shape with exterior tension members. In this system, the solid compression members are intersected each other and connected by a tension member in the center. This system is a variation of Tensegrity system, has a improved feature that the system is able to induce prestresses in all of tension members easily by adjusting the distance of a tension member in the center. The proposed system was studied by modeling, and the structural behavior of the system was investigated by mechanical analysis of the model. Furthermore, the features of the structural behavior variations was investigated when the composition elements(total height, size of surface, intersection length, etc.) are changed variously. It was also showed that the system is able to be used as a temporary space structure system with a membrane roof of inverse conical shape.

• Structural Engineering and Mechanics
• /
• 제39권1호
• /
• pp.93-113
• /
• 2011

The explicit nonlinear dynamic relaxation method (DRM) is applied to the nonlinear geodesic shape finding analysis by introducing fictional tensioned 'strings' along the desired seams with a three or four-node membrane element. A number of results from the numerical example for the nonlinear geodesic shape finding and patterning analysis are obtained by the proposed method to demonstrate the accuracy and efficiency of the developed method. Therefore, the proposed geodesic shape finding algorithm may improve the applicability of a four-node membrane element to membrane structural engineering and design analysis simultaneously for the shape finding, stress, and patterning analysis.

• 멤브레인
• /
• 제6권4호
• /
• pp.265-272
• /
• 1996

금속이온 분리를 위한 운반체 지지형 (고분자/운반체) 복합막을 수면전개법에 의하여 제조하였다. 이들 막의 형상은 전개용액의 물성에 의하여 영향을 받는다. (고분자/18-crown-6) 복합용액의 표면장력은 18-crown-6의 농도가 증가함에 따라 감소하는 경향을 나타내며, 고분자에 따른 용액의 표면장력은 PVC>PS>CA 순서로 감소하였다. 점도는 18-crown-6의 농도가 증가함에 따라 PVC계와 PS계 용액은 큰 변화가 없으나 CA계 용액은 감소하는 경향을 나타내었다. 18-crown-6 환형고리분자는 고분자쇄 사이에서 전기적인 완충역할을 하여 고분자쇄간의 분자간력을 약화시켜줌으로써 복합 용액의 전개성을 증가시켰다. 복합박막의 표면형상은 단일박막보다 균일하였으며, 18-crown-6가 증가함에 따라 전후면은 모두 균일한 구조극 나타내었다.

• 한국해양공학회지
• /
• 제15권2호
• /
• pp.22-32
• /
• 2001

The numerical investigation of obliquely incident wave interactions with fully submerged dual buoy/porous-membrane floating breakwaters placed in parallel with spacing is studied based on linear potential theory and Darcy's law. The numerical solutions are obtained by using a discrete-membrane dynamic model and second-kind modified Bessel function distribution over the entire boundaries of fluid regions. First, numerical solutions for an idealized dual submerged system without buoys are obtained. Second, a more practical dual submerged system with membrane tension provided by buoys at its tops is investigated by the multi-domain boundary element method particularly devised for dual buoy/porous-membrane problems with gaps. The velocity potentials of wave motion are coupled with porous-membrane deformation, and solved simultaneously since the boundary condition on porous-membrane is not known in advance. The effects of varying permeability on membranes and wave characteristics are discussed for the optimum design parameters of systems previously studied. The inclusion of permeability on membrane eliminates the resonances that aggravate the breakwater performance. The system is highly efficient when waves generated by the buoys and membranes were mutually canceled and its energy at resonance frequency dissipates through fine pores on membranes.

• Journal of Chest Surgery
• /
• 제20권3호
• /
• pp.451-457
• /
• 1987

Reoperations following cardiac surgery have an increased risk of the danger of damaging the heart, great vessels or extracardiac grafts because of adhesions to the sternum. We experimentally evaluated 3 different methods for pericardial closure. A standardized procedure for induction of pericardial adhesions was carried out in 30 rabbits. For closure of pericardium, animals were divided into 3 groups, 10 animals respectively: Croup 1 [simple pericardial closure]The pericardium was primarily resuture; Group 2 [Core-Tex surgical membrane as a pericardial substitute]- A Gore-Tex surgical membrane was interposed between the sternum and the heart; and Group 3 [pericardial tension releasing technique]-Three longitudinal overlapping incisions were made on the right side of the pericardium while the midline incison was sutured. Animals were put to death 4 weeks postoperatively and the pericardial space was examined for pericardial adhesions and epicardial reactions. The extent of adhesions and reactions were graded as: I-none; II-minimal; III-moderate; and IV-severe. Histologic studies of the pericardium, the pericardial substitute and the epicardium were also performed. The results were as follows: 1. In group 1 [simple pericardial closure], the degree of pericardial adhesions were grade I in 1 animal, grade II in 2, grade III in 4 and grade IV in 3. Epicardial reactions were grade I in 1 animal, grade II in 3, grade III in 5 and grade IV in 1. Histologic examination revealed thick fibrous tissue that obliterated the pericardial space in 7 animals. 2. In group 2 [Gore-Tex surgical membrane as a pericardial substitute], the degree of pericardial adhesions were grade I in 3 animals, grade II in 3, grade III in 2 and grade IV in 2. The degree of epicardial reactions were grade II in 1 animal, grade III in 5 and grade IV in 4. Histologic studies revealed a thin layer of dense fibrous tissue which covered the Gore-Tex surgical membrane and thick loose fibrous tissue on the epicardium just beneath the substitute. 3. In group 3 [pericardial tension releasing technique], the degree of pericardial adhesions were grade I in 3 animals, grade II in 4, grade III in 2 and grade IV in 1. The degree of epicardial reactions were grade 1 in 4 animals, grade II in 4 and grade III in 2. Severe epicardial reactions were not observed in this group. Histologic examination showed normal epicardium in 4 animals and the epicardium of the other 6 animals only revealed very thin fibrous layer compared to group I and group II. Pericardial adhesions more than grade III were 70% in group 1, 40% in group 2 and 30% in group 3. Pericardial adhesions were reduced in group 2 and group 3 compared to group 1, but statistically not significant. Epicardial reactions more than grade III were 60% in group 1, 90% in group 2 and 20% in group 3. Epicardial reactions were significantly reduced in group 3 compared to group 2. Author`s modified pericardial releasing technique provides marked augment of pericardial surface area and facilitates tension-free pericardial closure. Furthermore, pericardial adhesion and epicardial reaction will be reduced with the pericardial tension releasing technique.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제46권5호
• /
• pp.361-366
• /
• 2020

Guided bone regeneration (GBR) is a surgical procedure that utilizes bone grafts with barrier membranes to reconstruct small defects around dental implants. This procedure is commonly deployed on dehiscence or fenestration defects ≥2 mm, and mixing with autogenous bone is recommended on larger defects. Tension-free primary closure is a critical factor to prevent wound dehiscence, which is critical cause of GBR failure. A barrier membrane should be rigidly fixed without mobility. If the barrier is exposed, closed monitoring should be utilized to prevent secondary infection.

• 한국공간구조학회논문집
• /
• 제1권2호
• /
• pp.93-100
• /
• 2001

A stress-strain relationship for reinforced concrete membrane elements subjected to reversed cyclic loading is quite different to that of concrete cylinder subjected to uniaxial compression. The compressive strength of cracked concrete membrane elements is reduced by cracking due to tension in the perpendicular direction. Based on the three reinforced concrete panel tests, a softened stress-strain curve of concrete subjected to reversed cyclic loading is proposed. The proposed model consists of seven stages in the compressive zones and six stages in the tensile zones. The proposed model is verified by comparing to the test results.