• Steel and Composite Structures
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• 제4권1호
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• pp.1-8
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• 2004

Tests on steel tubular columns of square, rectangular and circular section filled with normal and lightweight aggregate concrete were conducted to investigate the failure modes of such composite columns. Thirty-six full scale columns filled with lightweight and normal weight aggregate concrete, eighteen specimens for each, were tested under axial loads. Nine hollow steel sections of similar specimens were also tested and results were compared to those of filled sections. The test results were illustrated by a number of load-deflection and axial deformation curves. The results showed that both types of filled columns failed due to overall buckling, while hollow steel columns failed due to bulging at their ends (local buckling). According to the above-mentioned results, and due to low specific gravity and thermal conductivity of the lightweight concrete the further interest should be concentrated in replacing the normal concrete by the lightweight aggregate concrete.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.34-34
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• 2010

This paper describes effect of the bending deformation of high voltage composite bushing with winding tension. The composite bushing can be formed, by adding silicone rubber sheds to a tube of composite materials. The FRP tube is internal insulating part of a composite bushing and is designed to ensure the mechanical characteristics. Generally the properties of FRP tube can be influenced by the winding angle, wall thickness and winding tension. As winding tension is increased glass contents was increased in the range of 70.4~76.6%. In the bending test, winding tension is increased residual deflection was decreased in the range of 14.0~12.2 mm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.125-128
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• 1997

They use a Ball End-mill in order to manufacturing sculptured surface when making metal mold, mold, cars and aircraft. In the work of a Ball End-mill case, customers do not often satisfied with manufacturing precision. Eventually, they have to re-work for the purpose of meeting manufacturing precision. There are resulted in lots of loss, whereby, in terms of both time and costs. The reasons of tolerance reducing manufacturing precision are thermal strain, the surface is damaged because of increasing cutting force and tool wear, tool deflection etc.. We focus on, however, manufacturing precision caused due to deflection of tool.

• 대한기계학회논문집B
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• 제27권6호
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• pp.804-812
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• 2003

This paper introduces optical methods for in-situ measurement of surface temperature and pressure transient in thermal processes having nanosecond time scales. In the temperature measurement, a p -Si thin film whose refractive index is calibrated as a function of temperature is embedded beneath the sample surface and the photothermal reflectance is monitored for estimating the surface temperature. The pressure transients are measured using the photoacoustic optical deflection method. The experimental technique is used to analyze the nanosecond laser induced vaporization process that is central to numerous engineering and bio-medical applications. Based on the experimental results, discussions are made on the experimental technique and the physical mechanisms of laser-driven explosive vaporization phenomena.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.130-131
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• 2019

As part of recent low-energy policies, thermal insulation standards for buildings are being tightened every year. In addition, the conventional styrofoam insulating material has a problem that the thickness of the heat insulating material to achieve a standard heat permeability is rapidly increased. Due to the thick insulation, there is a high risk of spreading vulnerable structures such as fire due to lack of space between buildings. On the other hand, the method of using the insulation as a formwork is known to be excellent cost saving effect through the reduction of the formwork usage and the simplification of the external insulation work. In order to solve this problem, this study aims to fabricate a multi-layered insulator that combines high-performance phenolic foam insulation and styrofoam insulation and evaluate the deflection characteristics for use as formwork.

• Journal of Electrical Engineering and Technology
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• 제1권2호
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• pp.263-267
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• 2006

A new thermal bimorph actuator for large out-of-plane displacement is designed, fabricated and tested. The deflecting beam is composed of polyimide, heater, and polyvinyl difluorides with tetrafluoroethylene (PVDF-TrFE). The large difference of coefficient of thermal expansion (CTE) of two polymer layers (polyimide and PVDF-TrFE) can generate a significant deflection with relatively small temperature rise. Compared to the most conventional micro actuators based on MEMS (micro-electro mechanical system) technology, a large displacement, over 1 mm at 20 mW, could be achieved. Additionally, we can achieve response time of 14.6 ms, resonance frequency of 12 Hz, and reliability ability of $10^5$ cycles. The proposed actuator can find applications where a large vertical displacement is needed while maintaining compact overall device size, such as a micro zooming lens, micro mirror, micro valve and optical application.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1286-1289
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• 2004

A new thermal bimorph actuator for large out-of-plane displacement is designed, fabricated and tested. The deflecting beam is composed of polyimide, heater, and polyvinyl difluorides with tetrafluoroethylene(PVDF-TrFE). The large difference of coefficient of thermal expansion(CTE) of two polymer layers (polyimide and PVDF-TrFE) can generate a large deflection with relatively small temperature rising. Compared to the most conventional micro actuators based on MEMS(micro-electro mechanical system) technology, a large displacement, over 1 mm at 20 mW, could be achieved. The proposed actuator can find applications where a large vertical displacement is needed while keeping compact overall device size, such as a micro zooming lens.

• Journal of Mechanical Science and Technology
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• 제20권3호
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• pp.297-309
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• 2006

This paper deals with a novel structure for single-cell characterization which makes use of bimorph micro thermal actuators combined with electrical sensor device and integrated microfluidic channel. The goal for this device is to capture and characterize individual biocell. Quantitative and qualitative characteristics of bimorph thermal actuator were analyzed with finite element analysis methods. Furthermore, optimization for the dimension of cantilevers and integrated parallel probe systems with microfluidic channels is able to be realized through the virtual simulation for actuation and the practical fabrication of prototype of probes. The experimental value of probe deflection was in accordance with the simulated one.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.303-310
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• 2002

The bending vibration and thermal flutter instability of spacecraft booms modeled as circular thin-walled beams of closed cross-section and subjected to thermal radiation loading is investigated in this paper. Thermally induced vibration response characteristics of a composite thin walled beam exhibiting the circumferantially uniform system(CUS) configuration are exploited in connection with the structural flapwise bending-lagwise bending coupling resulting from directional properties of fiber reinforced composite materials and from ply stacking sequence. The numerical simulations display deflection time-history as a function of the ply-angle of fibers of the composite materials, damping factor, incident angle of solar heat flux, as well as the boundary of the thermal flutter instability domain. The adaptive control are provided by a system of piezoelectric devices whose sensing and actuating functions are combined and that an bonded or embedded into the host structure.

• Geomechanics and Engineering
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• 제29권6호
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• pp.667-681
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• 2022

This paper presents a thermoelastic analysis of variable thickness plates made of functionally graded materials (FGM) subjected to mechanical and thermal loads. The thermal load is applied to the plate as a temperature difference between the top and bottom surfaces. Temperature distribution in the plate is obtained using the steady-state heat equation. Except for Poisson's ratio, all mechanical properties of the plate are assumed to vary linearly along the thickness direction based on the volume fractions of ceramic and metal. The plate is resting on an elastic foundation modeled based on the Winkler foundation model. The governing equations are derived based on the third-order shear deformation theory (TSDT) and are solved numerically for various boundary conditions using the differential quadrature method (DQM). The effects of various parameters on the stress distribution and deflection of the plate are investigated such as the value of thermal and mechanical loads, volume fractions of ceramic and metal, and the stiffness coefficients of the foundation.