• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.1
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• pp.1-9
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• 2010

The actual hysteretic behavior of structural elements and systems is closer to smooth hysteretic behavior than piece-wise linear behavior. This paper presents a methodology for computing the constant-ductility inelastic response spectra for smooth hysteretic behaviors. The effect of the hysteretic smoothness on the inelastic response spectra for acceleration, displacement, and input energy is evaluated. The results indicate that increasing smoothness in the hysteretic behavior decreases the inelastic response spectra.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.4
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• pp.353-362
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• 2016

An accurate hysteresis model of an elastomer is important for quantifying viscoelastic energy loss. We suggest a highly nonlinear hyper-viscoelastic constitutive model of elastomers. The model captures a nonlinear viscoelastic characteristic by combining Yeoh's hyperelastic model and Hoofatt's hysteresis model used Neo-Hookean hyperelastic model. Analytical and numerical models were generated from uniaxial cyclic tests of an elastomer under a sinusoidal load with a mean strain of 150%, amplitudes of 20~80%, and frequencies of 0.02~0.2Hz. The viscoelastic model can highly capture the viscoelastic energy loss up to a strain of 230%.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.545-550
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• 2023

A pretensioner is a safety device that protects occupants by pulling the seat belt in the event of a vehicle collision. However, since the pretensioner is driven by a explosive method, it is necessary to replace not only the gas generator but also all connecting parts including the manifold after an accident. Therefore, in this paper, we propose an elastic force-based pretensioner that can be used safely and semi-permanently. After analyzing the operating mechanism of the existing pretensioner from a thermodynamic/dynamic point of view, the spring stiffness that can be deployed within an appropriate operating time was determined by converting the gas explosion energy into elastic energy. In addition, the coil spring shape that satisfies the elastic stiffness was designed in consideration of the vehicle interior installation standard. Finally, the operating performance of the pretensioner driven by elastic force was verified through fabrication.

• Composites Research
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• v.37 no.2
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• pp.132-138
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• 2024

In this study, a molecular dynamics simulation study was performed to investigate the size-dependent electroelastic properties of single-walled boron nitride nanotubes(BNNT). To describe the elasticity and polarization of BNNT under mechanical loading, the Tersoff potential model and rigid ion approximation were adopted. For the prediction of piezoelectric constants and Young's modulus of BNNTs, piezoelectric constitutive equations based on the Maxwell's equation were used to calculate the strain-electric displacement and strain-stress relationships. It was found that the piezoelectric constants of BNNTs gradually decreases as the radius of the tubes increases showing a nonnegligible size effect. On the other hand, the elastic constants of the BNNTs showed opposites trends according to the equivalent geometrical assumption of the tubular structures. To establish the structure-property relationships, localized configurational change of the primarily bonded B-N bonded topology was investigated in detail to elucidate the BNNT curvature dependent elasticity.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1999.06a
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• pp.25-30
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• 1999

자동차의 정면 충돌시 발생하는 충돌에너지를 흡수하여 인명을 보호하기 위한 장비중 구조 역학적 관점에서 고려될 수 있는 것으로 범퍼와 사이드멤버(Side Member)가 있다. 이들중 범퍼는 시속 8km/hr 이하의 저속 충돌시에 탄성 변형에너지로서 충돌에너지를 흡수하는 역할을 하나, 그 이상의 고속 정면 충돌시에는 일반적으로 사이드멤버가 충돌에너지의 60∼70%를 부재의 연속적인 대변형에 의한 소성에너지에 의해 흡수하고 있다. (중략)

• Journal of the Korean Magnetics Society
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• v.5 no.2
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• pp.115-118
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• 1995

We predict the magnetization curves with strains in thin films. It is possible to predict the magretoelastic ani¬sotropy erergy which generates the changes of the M-H curves in thin films. We show the prediction of M-H curves in case of isotropic films such as polycrystalline am amorphous thin films as well as single crystal cubic films.

• Magazine of the Korea Concrete Institute
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• v.4 no.4
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• pp.149-160
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• 1992

콘크리트 압축강도가 설계의 규준이 될 경우 배합비를 결정하는 방법은 여러 가지가 있으나, 파괴에너지 및 탄성계수와 같은 규준이 주어질 경우 배합비 결정에 적용하는 방법은 거의 없다. 이를 위하여 본 연구는 콘크리트 재료성질의 관계에 관한 배합설계도(Mix design diagram)를 제안하였다. 이 방법은 시멘트량, 물-시멘트 비가 콘크리트의 압축강도, 탄성계수, 할렬인장강도, 파괴에너지 그리고 콘크리트 특성길이(Characteristic length)에 주는 영향을 실험에 의하여 규명하였다. 시편제작을 위하여 각기 다른 물-시멘트비와 워커빌리티를 갖는 6종류의 무근콘크리트 배합이 사용되었다.

• Journal of Korean Society of Steel Construction
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• v.13 no.2
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• pp.163-176
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• 2001

In this paper, the stress resultants and displacements of simply supported curved girder based on the flexural torsional theory considering torsional warping effects are analyzed. And elastic equations of continuous curved girder are obtained by using energy method. Also, bending moment warping torsional moment diagram, pure torsional moment diagram, shearing force diagram, and deflection diagram of continuos curved girder bridge subjecting to vertical loads and uniform loads are presented.

• Journal of the Korean Solar Energy Society
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• v.28 no.1
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• pp.25-32
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• 2008

Aeroelastic phenomena of a wind turbine include stall-induced vibrations and classical flutters. The classical flutter occurs due to coalescence between bending mode and torsion mode. It is typically the aeroelastic instability of an aircraft wing. Different from the classical flutter, the stall-induced vibration is the instability in lead-lag mode due to negative aerodynamic dampings. In the present study, the three degree of freedom aeroelastic model of a wind turbine blade is introduced to characterize and analyze its aeroelastic phenomena. The numerical results show that the aeroelastic stability of flap-lag motion is more unstable than that of flap-pitch motion and the aeroelastic characteristics of lead-lag motion can become unstable as wind speed increases.

• Electrical & Electronic Materials
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• v.6 no.3
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• pp.233-240
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• 1993

더블히트파이프장치를 이용하여 순수 Ar, Hg 및 Ar-Hg 혼합증기의 전자이동속도를 온도는 순수 Ar의 경우 293[.deg.K], Hg의 경우 453-540[.deg.K]. Ar-Hg 혼합증기의 경우 320[.deg.K], E/N은 0.4~10[Td], 기체압력은 10~100[Torr]범위에서 유도전류법에 의해 측정하였다. 한편 볼츠만 방정식의 Backward Prolongation계산법으로 전자에너지분포함수를 구하고 그 값으로부터 전자수송특성을 산출하여 실험치와 비교하고 탄성 및 비탄성 충돌 단면적을 결정하였다. 그리고 Ar기체에 Hg증기를 0.5%, 1%, 5%, 10% 혼합하였을 때의 전자에너지분포함수와 전자이동속도를 산출하고 그에 미치는 영향을 고찰하였다.