• 한국강구조학회 논문집
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• 제9권1호통권30호
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• pp.13-22
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• 1997

This paper is concerned with an experimental study on structural behavior of Concrete-Filled Circular Tubular(CFCT) column to H-beam connections. The important parameters are the number of inner reinforced rib and the width of H-beam flange(100, 150, 200mm) with variable column thickness(5.8mm, 9.2mm, 12.5mm) around the joint between CFCT and H-beam. Test results are summarized for the displacement, strength, initial stiffness, failure mode and energy absorption capacity of each specimen. The purpose of this paper is to investigate the initial stiffness and the strength of connections to evaluate the structural behavior of the CFCT column to H-beam connections. From the discussion about the test results, the basic data for non diaphragm connection design would be suggested.

• Steel and Composite Structures
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• 제6권1호
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• pp.55-69
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• 2006

The results of tests conducted on 11 concrete-filled steel tubular columns were reported. Concrete was partially filled in circular steel tubular columns. The primary test parameters were radius and thickness of steel tubes, concrete height, loading patterns and attachment of diaphragm and studs. Concrete strain was measured directly by embedding strain gauges so that the effect of diaphragm on concrete confinement could be investigated. The effects of concrete height and diaphragm on ultimate strength and ductility of steel tubes were investigated. The comparisons of the test results with the existing results for rectangular cross-sections were made on the basis of ultimate strength and ductility of concrete-filled steel tubular columns.

• 대한전자공학회논문지
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• 제23권3호
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• pp.364-369
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• 1986

Silicon diaphragms, 10 and 20 \ulcorner-thick and 1x1 mm\ulcornerarea, have been fabricated by means of the electrochemical P-N junction etch-stop technique. The P-type diffused resistors were formed on the diaphragm, and the piezoresistance effect was examined. It was been found that the fractional variation of the resistance is dependent on the diaphragm thickness, resistor location, and resistor length, etc. The 1.2 k\ulcornerfull-brige pressure sensor with 10\ulcorner-thick diaphragm exhibits a pressure sensitivity of 42 \ulcorner/V\ulcornermHg with a temperature coefficient of 2.3 mmHg/\ulcorner, and shows a good linearity in the pressure range from 0 to 300 mmHg.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권4호
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• pp.137-141
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• 2004

In this paper, a thermopneumatic PMDS (polydimethlysiloxane) micropump with nozzle/diffuser elements is presented. The micropump is composed of nozzle/diffuser elements as dynamic valves, an actuator consisting of a circular PDMS diaphragm and a Cr/Au heater on a glass substrate. Four PDMS layers are used for fabrication of an actuator chamber, actuator diaphragm by a spin coating process, spacer layer, and nozzle/diffuser by the SU-8 molding process. The radius and thickness of the actuator diaphragm is 2 mm and 30 ${\mu}{\textrm}{m}$, respectively. The length and the conical angle of the nozzle/diffuser elements are 3.5 mm and 20$^{\circ}$, respectively. The actuator diaphragm is driven by the air cavity pressure variation caused by ohmic heating and natural cooling. The flow rate of the micropump in the frequency domain is measured for various duty cycles of the square wave input voltage. When the square wave input voltage of 5 V DC is applied to the heater, the maximum flow rate of the micropump is 44.6 ${mu}ell$/min at 100 Hz with a duty ratio of 80% under the zero pressure difference.

• Advances in Computational Design
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• 제2권2호
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• pp.107-119
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• 2017

The Micro circular diaphragm (MCD) is the mechanical actuator part used in the micro electro-mechanical sensors (MEMS) that combine electrical and mechanical components. These actuators are working under harsh mechanical and thermal conditions, so it is very important to study the mechanical and thermal behaviors of these actuators, in order to do with its function successfully. The objective of this paper is to determine the thermo-mechanical behavior of MCD by developing the traditional bulge test technique to achieve the aims of this work. The specimen is first pre-stressed to ensure that is no initial deflection before applied the loads on diaphragm and then clamped between two plates, a differential pressure (P) and temperature ($T_b$) is leading to a deformation of the MCD. Analytical formulation of developed bulge test technique for MCD thermo-mechanical characterization was established with taking in-to account effect of the residual strength from pre-stressed loading. These makes the plane-strain bulge test ideal for studying the mechanical and thermal behavior of diaphragm in both the elastic and plastic regimes. The differential specimen thickness due to bulge effect to describe the mechanical behavior, and the temperature effect on the MCD material properties to study the thermal behavior under deformation were discussed. A finite element model (FEM) can be extended to apply for investigating the reliability of the proposed bulge test of MCD and compare between the FEM results and another one from analytical calculus. The results show that, the good convergence between the finite element model and analytical model.

• 대한기계학회논문집A
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• 제27권3호
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• pp.401-408
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• 2003

A CAD program for metal bellows diaphragm was developed in this study. This program was written in AutoLISP on the AutoCAD system with a personal computer. Basic design concept used in this program is composition of a convolution that is tangent to two lines and 5 circles from given design parameters(initial radius, inner and outer diameter, thickness, pitch, etc.). The effects of altering some design parameters on stress distribution and fatigue life of bellows were estimated using commercial FEM code, NISAII. As a result, the metal bellows diaphragm was successfully designed by the CAD program. It is used to model a bellows geometry in pre-processor of FEM code. The FEM result shows that stress is dependent on straight line length, bellows diameter with same span, and fatigue life is also affected by design parameters.

• Structural Engineering and Mechanics
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• 제64권2호
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• pp.195-204
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• 2017

Analytical and experimental studies of the innovative pipe in pipe damper have been recently investigated by the authors. In this paper, by adding lead or zinc infill or slit diaphragm inside the inner pipe, it is tried to increase the equivalent viscous damping ratio improving the cyclic performance of the recently proposed multi-level control system. The damper consists of three main parts including the outer pipe, inner pipe and added complementary damping part. At first plastic deformations of the external pipe, then the internal pipe and particularly the added core and friction between them make the excellent multi-level damper act as an improved energy dissipation system. Several kinds of added lead or zinc infill and also different shapes of slit diaphragms are modeled inside the inner pipe and their effectiveness on hysteresis curves are investigated with nonlinear static analyses using finite element method by ABAQUS software. Results show that adding lead infill has no major effect on the damper stiffness while zinc infill and slit diaphragm increase damper stiffness sharply up to more than 10 times depending on the plate thickness and pipe diameter. Besides, metal infill increases the viscous damping ratio of dual damper ranging 6-9%. In addition, obtained hysteresis curves show that the multi-level control system as expected can reliably dissipate energy in different imposed energy levels.

• 한국지반공학회논문집
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• 제30권9호
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• pp.5-17
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• 2014

지하수위가 높은 지역에 설치된 지중연속벽 주변지반 속에 발생되는 지중파괴면의 형상을 조사하기 위해 일련의 모형실험을 실시하였다. 모형실험에서 벽체가 인발될 때 발생하는 벽체 주변지반의 변형거동을 사진으로 촬영하여 관찰하였고 이 지반변형 결과를 분석하여 지중연속벽 주변지반에 발생되는 지중파괴면의 형상을 파악할 수 있었다. 이렇게 파악된 지중파괴면의 형상에 근거하여 지중연속벽의 인발저항력을 산정할 수 있는 이론해석을 실시하였다. 이 이론해석에는 벽체와 지반에 관한 주요 특성이 잘 반영되어 있다. 즉 벽체의 특성으로는 벽체의 길이, 두께 및 벽면조도가 포함되어 있으며 지반의 특성에 관하여는 흙의 내부마찰각 및 점착력과 같은 전단강도정수가 포함되어있다. 제안된 해석모델에 의거하여 예측된 지중연속벽의 인발저항력은 모형실험에서 측정된 실험치와 잘 일치하였다.

• 한국강구조학회 논문집
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• 제20권6호
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• pp.711-722
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• 2008

기존 콘크리트충전 각형강관(CFT) 구조에 사용하는 각형강관은 4개의 판을 용접하여 제작하는 박스칼럼이 일반적이다. 그러나 이러한 강관은 제작효율이 저하되며, 또한 기둥-보 접합부에는 내측 다이아프램과 관통 다이아프램을 용접하는데 특수한 용접기술이 필요하다. 따라서, 얇은 강판을 절곡하는 방식으로 응력집중 위치의 용접을 피하고, 단면효율이 극대화된 내부앵커 돌출형의 각형강관을 개발하게 되었다. 본 연구에서는 이 개발된 강관의 기둥-보 접합부로 외다이아프램형식을 채택하고. 보 플랜지의 응력 전달을 명확히 하기 위한 기둥-보 접합부 상세를 확 정하고자 이 접합부에 대한 단순인장 실험체를 제작하여 성능평가 실험을 수행하였다. 이 실험을 통해 콘크리트충전 기둥-보 접합부의 기둥-보 플랜지 용접 유무, 기둥-다이아프램 용접량, 콘크리트 충전유무, 다이아프램 설치 기둥과 일반기둥의 비교 등에 따른 인장영역 응력분포 및 내력평가를 진행하고 내부 앵커와 콘크리트 사이의 합성효과를 파악하였다.

• 한국강구조학회 논문집
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• 제28권2호
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• pp.75-83
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• 2016

기존 콘크리트충전 각형강관(CFT) 구조에 사용하는 각형강관은 4개의 판을 용접하여 제작하는 박스칼럼이 일반적이다. 그러나 이러한 강관은 제작효율이 저하되며, 또한 기둥-보 접합부에는 내측 다이아프램과 관통 다이아프램을 용접하는데 특수한 용접기술이 필요하다. 따라서, 얇은 강판을 절곡하는 방식으로 응력집중 위치의 용접을 피하고, 단면효율이 극대화된 내부앵커 돌출형의 용접조립 각형강관을 개발하게 되었다. 용접조립 각형강관은 강관내부에 스티프너가 설치되어 내측 다이아프램과 관통 다이아프램과 간섭이 발생하게 되므로 본 연구에서는 용접조립 각형CFT 기둥-보 접합부로 외다이아프램형식을 채택하고 외다이아프램의 설계식을 제안하였으며, 기둥-보 접합부의 거동을 파악하기 위해 실대형 4개 실험체를 제작하여 구조거동 및 내력을 분석하였다.