• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.232-235
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• 1998

ion conducting polymers have been extensively investigated because of their potential application as an electrolyte in solid state batteries [1]. Among the polymer electrolytes, solid polymer electrolytes (SPEs) composed of ion conducting polymer and alkali metal salt have many advantages such as high ionic conductivity, high energy density and light weight. This made them suitable replacement for liquid electrolytes. (omitted)

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.157-160
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• 2003

Honeycomb sandwich composite structures have been widely used in aircraft and military industry because of light weight and high stiffness. Accurate mechanical properties of honeycomb materials are needed for analysis of sandwich composites. In this study, theoretical formula for elastic modulus of honeycomb materials was established considering bending and axial deformations of their walls. Finite-element analysis results were compared with theoretical ones of the longitudinal and transverse moduli of honeycomb materials. Consequently, the mechanical properties of honeycomb materials could be analytically predicted.

• Smart Structures and Systems
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• v.20 no.5
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• pp.637-640
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• 2017

The adoption of cladding panels as dissipation device is a sort of passive control "ante litteram" for residential and commercial buildings. This paper gives details on the current technology outlining the difference between buffer panels and cladding panels. The discussion of robustness and resilience of the resulting system is afforded. It is shown that the strength of such solution, originally related to economy and light weight, is mainly associated with the respect of the main robustness requisites, as well as the short time it requires for removal and replacement (resilience).

• Journal of the Korean Society of Safety
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• v.11 no.3
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• pp.33-43
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• 1996

In this paper, collapse test of thin-walled structures, which are widely used in the vehicle members is carried out to observe the dependence of cross-sectional forms and materials on the absorbed energy in the viewpoint of crashworthiness. Also, specimens consist of two kinds (Al, CFRP) with various thickness. Comparisons of circular specimens are made to find characteristics of the different specimens on the absorption ability according to specimen thickness and materials.

• Magazine of the Korea Concrete Institute
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• v.11 no.2
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• pp.77-84
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• 1999

Recently, it is increased the use of High-Strength Light-Weight Concrete(HLC) in the high-rise buildings and mega-structures. But there are a few research on the bond behavior of HLC, so it need to study about that. The present study was performed to investigate the bond characteristics of HLC. Major test variables include concrete compressive strength(f'c), concrete cover(c), bond length (${\ell}_{db}$), and bar diameter($d_b$). Test results indicate that the bond stress of HLC is increased with the increment of $\sqrt{f'_c}$ and concrete cover, bond stress is decreased with increment of bond length and bar diameter. And the final failure mode such as splitting or pullout failure is significantly affected by the concrete cover to bar diameter ratios(C/$d_b$). Test results were compared with ACI code and other proposed equations. The bond stress of HLC is higher than that of normal-strength normal-weight concrete, but lower than that of high-strength normal-weight concrte. Considering the present test results, modification factor(${\lambda}$= 1.3) of bond length in ACI 318-95 code for light-weight concrete is may have to be reviewed to apply to HLC.

• Journal of Aerospace System Engineering
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• v.12 no.4
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• pp.18-25
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• 2018

The head frame structure of a machine tool for aircraft parts, which requires machining precision and machining of difficult-to-cut materials is required to be light-weighted for precision high-speed machining and to minimize possible deformation by cutting force. To achieve high stiffness and for light-weight structure optimization design, a preliminary model was designed based on finite element analysis. The topology optimization design of light-weight, high stiffness, and low vibration frame structure were performed by minimizing compliance. As a result, the frame weight decreased by 17.3%, the maximum deflection was less than 0.007 mm, and the natural frequency increased by 30.6%. The static stiffness was increased in each axis direction and the dynamic stiffness exhibited contrary results according to the axis. Optimized structure with the high stiffness of low vibration in topology optimization design was confirmed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2502-2512
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• 2000

Truss structures are widely used in many space structures, such as large antenna systems, space stations, precision segmented telescopes because they are light in weight and amenable in assembly or deployment. But, due to the low damping capacity, they remain excited for a long time once disturbed. These structural vibrations can reduce life of the structures and cause unstable dynamic characteristics. In this research, vibration suppression experiment has carried out with a three-dimensional 15-member truss structure using two piezoelectric actuators. Piezoelectric actuators which consist of stacks of thin piezoelectric material disks are directly inserted to the truss structure collocated with the strain sensors. Each actuator is controlled digitally in decentralized manner, based on local integral and proportional feedback. The optimal positions of the actuators are determined by the modal damping ratio and the control force. Numerical simulation has carried out to determine optimal position of each actuator.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.93-100
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• 1998

The basic systems of spatial structures such as shells, membrane, cable-nets and tensegrity structure have been developed to create the large spaces without column. These structures may have large freedom in scale and form, and especially tensegrity structures are received much attention from the view points of their light weight and aesthetics. But There re some difficulties concerning structural stability, surface formation and construction method. One of the way to solve these problems reasonably is a combination of tensile members and rigid members. A structural system based on this concept is referred to as the "HTS ( Hybrid Tension Structure )". This is a type of flexible structural system which is unstable initially, because the cable material has little initial rigidity. As cable - dome hybrid structures is a type of HTS, the initial stress for the self- equilibrated system having stable state have to be introduced. To determine initial stress having stable state, the shape finding analysis is required before the stress - deformation analysis. In this paper, the primary objective is to derive the nonlinear finite element formula of cable and truss members considering geometric nonlinearity for shape finding of cable-dome, and to propose the method to decide the initial stress by the shape analysis of cable-dome hybrid structure with the self-equilibrated state.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.55.4-56
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• 2018

Linear Astigmatism Free - Three Mirror System (LAF-TMS) is the linear astigmatism free off-axis wide field telescope with D = 150 mm, F/3.3, and $FOV=5.51^{\circ}{\times}4.13^{\circ}$. We report the design and analysis results of its mirrors and optomechanical structures. Tolerance allowance has been analyzed to the minimum mechanical tolerance of ${\pm}0.05mm$ that is reasonable tolerance for fabrication and optical alignment. The aluminum mirrors are designed with mounting flexure features for the strain-free mounting. From Finite Element Analysis (FEA) results of mounting torque and self-weight, we expect 33 - 80 nm RMS mirror surface deformations. Shims and the L-bracket are mounted between mirrors and the mirror mount for optical alignment. The mirror mount is designed with four light-weighted mechanical parts. It can stably and accurately fix mirrors, and it also suppresses some of stray light.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.26-31
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• 2002

The recent machine tools are requested so high-quality processing and productivity increasing. Therefore, it is so necessary to develop technology fur high-speed and high-precision. This thesis touches on the development of high speed and intellectual line center. At first, the line center is necessary that strong structure, compact structure and light weight design for high-speed processing and transfer. So, it is necessary that examination of new materials and structures for light-weight and control devices for precision processing. So. it is going to make mention of the process of 1st model production for the above-mentioned based on test model production and evaluation.