• 상하수도학회지
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• 제30권4호
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• pp.417-425
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• 2016

Desalination is a key technology to overcome water shortage problem in a near future. High energy consumption is an Achilles' heel in desalination technology. Osmotically driven membrane processes like forward osmosis(FO) was introduced to address this energy issue. Characterizing membrane properties such as water permeability(A), salt permeability(B), and the resistance to salt diffusion within the support layer($K_{ICP}$) are very important to predict the performance of scaled-up FO processes. Currently, most of researches reported that the water permeability of FO membrane was measured by reverse osmosis(RO) type test. Permeating direction of RO and FO are different and RO test needs hydraulic pressure so that several problems can be occurred(i.e. membrane deformation, compaction and effect of concentration polarization). This study focuses on measuring water permeability of FO membrane by FO type test results in various experimental conditions. A statistical approach was developed to evaluate the three FO membrane properties(A, B, and $K_{ICP}$) and it predicted test result by the internal and external concentration polarization model.

• 한국공간구조학회논문집
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• 제21권4호
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• pp.49-56
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• 2021

This study aims to develop a form-finding algorithm for a single-layered pneumatic membrane. The initial shape of this pneumatic membrane, which is an air-supported type pneumatic membrane, is to find a state in which a given initial tension and internal pneumatic pressure are in equilibrium. The algorithm developed to satisfy these conditions is that a nonlinear optimization problem based on the force method considering the deformed shape is formulated, and, it's able to find the shape by iteratively repeating the process of obtaining a solution of the governing equations. An computational technique based on the Gauss-Newton method was used as a method for obtaining solutions of nonlinear equations. In order to verify the validity of the proposed form-finding algorithm, a single-curvature pneumatic membrane example and a double-curvature air pneumatic membrane example were adopted, respectively. In the results of these examples, it was possible to well observe the step-by-step convergence process of the shape of the pneumatic membrane, and it was also possible to confirm the change in shape according to the air pressure. In addition, the calculation results of the shape and internal force after deformation due to initial tension, air pressure, and self-weight were obtained.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 The Korea-Japan Joint Symposium
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• pp.104-104
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• 2003

Geosynthetic Reinforcements - membrane drawn type, warp/knitted type, junction bonded type and composite type geogrids, strip type reinforcement - were used to compare the long-term perfor-mance by total factor of safety with reduction factors during service periods. To evaluate the reduction factors, wide-width tensile property, installation damage, creep deformation, chemical and biological degradation tests were performed. Long-term design strengths of geosynthetic reinforcements were calculated by using GRI standard Test Method GG4.

• 한국공간구조학회논문집
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• 제17권3호
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• pp.45-55
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• 2017

The objective of this study is to estimate the mechanical characteristics and nonlinear behaviors on the geometric nonlinear analysis of curved cable-membrane roof systems for long span lightweight roof structures. The weight of a cable-membrane roof dramatically can reduce, but the single layer cable-membrane roof systems are too flexible and difficult to achieve the required structural stiffness. A curved cable roof system with reverse curvature works more effectively as a load bearing system, the pretension of cables can easily increase the structural stiffness. The curved cable roof system can transmit vertical loads in up and downward direction, and work effectively as a load bearing structure to resists self-weights, snow and wind loads. The nonlinear behavior and mechanical characteristics of a cable roof system has greatly an affect by the sag and pretension. This paper is carried out analyzing and comparing the tensile forces and deflection of curved roof systems by vertical loads. The elements for analysis uses a tension only cable element and a triangular membrane element with 3 degree of freedom in each node. The authors will show that the curved cable-membrane roof system with reverse curvature is a very lightweight and small deformation roof for external loads.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권7호
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• pp.298-304
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• 2003

IPMC(Ionic Polymer-Metal Composite) is a highly sensitive actuator that shows a large deformation in presence of low applied voltage. Generally, IPMC can be fabricated by electroless plating of platinum on both sides of a Nafion (perfluorosulfonic acid) film. When a commercial Nafion film is used as a base structure of the IPMC membrane, the micro-pump structure and the IPMC membrane are fabricated separately and then later assembled, which makes the fabrication inefficient. Therefore, fabrication of an IPMC membrane and the micro-pump structure on a single wafer without the need of assembly have been developed. The silicon wafer was partially etched to hold liquid Nafion to be casted and a 60-${\mu}{\textrm}{m}$ thick IPMC membrane was realized. IPMC membranes with various size were fabricated by casting and they showed 4-2${\mu}{\textrm}{m}$ displacements from $4mm{\times}4mm$ , $6mm{\times}6mm$, $8mm{\times}8mm$ membranes at the applied voltage ranging from 2Vp-p to 5Vp-p at 0.5Hz. The displacement of the fabricated IPMC membranes is fairly proportional to the membrane area and the applied voltage.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.111-116
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• 2003

Instrumentation system in Concrete Face Rockfill Dam(CFRD) can give special attention to the deformation characteristics of the rockfill and behavior of the concrete membrane during construction, reservoir filling and subsequent phase of operation. It also contains data about vertical and transversal compressibility moduli of the rockfill, deflections in the concrete slab, and draws comparisons with other concrete face rockfill dams of recent construction. In this paper, the internal deformation data from D dam monitored by means of hydrostatic settlements cells are analyzed. Observations cover the construction stage, reservoir filling and up to March 1991. The above method can be concluded D dam was well constructed and maintained.

• 대한기계학회논문집
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• 제17권10호
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• pp.2535-2542
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• 1993

Two-noded curved beam elements, CMLC (field-consistent membrane and linear curvature) and IMLC(field-inconsistent membrane and linear curvature) are developed on the basis of Timoshenko's beam theory and curvilinear coordinate. The curved beam element is developed by the separation of the radial deflection into the bending deflection. In the CMLC element, field-consistent axial strain interpolation is adapted for removing the membrane locking. The CMLC element shows the rapid and stable convergence on the wide range of curved beam radius to thickness. The field-consistent axial strain and the separation of radial deformation produces the most efficient linear element possible.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
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• pp.260-267
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• 1999

In this paper, We propose the initial shape finding and dynamic analysis of cable dome structure are presented. Cable dome that is consist of three component such as cable, strut and fabric membrane have complex structural characteristics. Main structural system of cable dome is cable-strut tensegric system, and fabric membrane element Is conceived as cladding roof material. One of the important problem of cable dome is shape finding of those subjected to cable and membrane forces, which stabilize the structures. And the other is structural response from external load effect such as snow and wind When cable dome are subjected to dynamic load such as wind load each structural component has many important problem because of their special structural characteristics. One problem is that geometrical nonlinearity should be considered in the dynamic analysis because large deformation is occurred from their flexible characteristic. The other problem is that wrinkling occurs occasionally because cable and membrane elements can not transmit compressive forces. So this paper describe the physical structural response of cable dome structure.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.183-187
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• 1997

A membrane element is regarded as more preferable rather than other elements in the sense of its computing efficiency and the merit with respect to contact treatment. However, it cannot consider the bending effect during the deformation. Moreover, due to the characteristics of rolling process, sheet metal has anisotropy with respect to the direction in the plane. To take the bending effect into account, a modified membrane element was introduced and improved to consider planar anisotropic characteristics with the aid of Hill's quadratic criterion.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 추계학술대회논문집
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• pp.98-101
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• 1997

Membrane panels for LNG(Liquid Natural Gas) tank are formed to corrugared ones by press forming. The environment of LNG tank is so severe that the service temperature is -162$^{\circ}C$ and the room temperature is 20$^{\circ}C$. The thermal deformation derived by the severe temperature change is absorbed by the corrugations of the membrane panels. In this paper the formability of stainless steel membrane panel is examined by the finite element analysis. Two corrugated shapes are suggested, and analyzed to obtain a sound absorption performance of the thermal distortion. Also the design considers forming characteristics and economy of production.