• Korea-Australia Rheology Journal
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• v.12 no.3_4
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• pp.151-155
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• 2000

A semiconducting poly(naphthalene quinone) radical (PNQR) was synthesized from Friedel-Craft acylation between naphthalene and phthalic anhydride and used as dispersing particles of a dry-base electrorheological (ER) material in silicone oil. Under an applied electric field (E), the dynamic yield stress (${\tau}_{dyn}$) of this ER fluid, obtained from a steady shear experiment with a controlled shear rate mode, was observed to increase with $E^{1.45}$ Based on this relationship, we propose a universal correlation curve for shear viscosity, which is independent of E using a scaling analysis.

• Journal of KSNVE
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• v.1 no.2
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• pp.107-113
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• 1991

When non-contact type vibration probes are used for the precision measurement of shaft vibration, they can induce the measurement errors due to the shaft curvature since they have been calibrated for the flat plate. In this study the errors due to the shaft radius and the misalignment between the shaft and probe centerlines are analyzed, and an in-situ calibration tool, which can be conveniently used for calibration independent of the shaft curvature and material, is introduced.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.105-111
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• 2009

Dielectric breakdown in piezoelectric ceramics is analyzed by using the three dimensional J integral. The J integral is shown to be a path-independent surface integral for a conductive tubular channel in a piezoelectric material. J integrals are also numerically calculated for conductive defects and tubular channels in piezoelectric ceramics through finite element analysis.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.37-42
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• 2004

The primary objective of this paper is to trace the post-buckling behavior of space trusses in the inelastic range. Modeled member material behavior characteristics of struts in the post-critical elasto-plastic stage are determined and three types of idealized hardening rules are described. To perform this analysis, the present work is used the current stiffness parameter method combined with the cylinderical arc-length method. Numerical examples are presented to illustrate the accuracy and the application of the numerical solutions introduced above.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.60-60
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• 2012

본 발표에서는 물 또는 용매 속에서 어떤 물질의 표면도 개질할 수 있는 표면공학기법에 대해 발표하고자 한다. 본 기술은 홍합의 접착단백질의 성분에서 착안한 polydopamine 및 catecholamine으로 정의되는 일련의 chemical compounds에 의해 수행된다. 먼저 polydopamine의 형성 원리를 설명 하고 이를 이용하여, 에너지, 물, 나노바이오 등 다양한 분야의 응용예를 소개 할 예정이다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.157-164
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• 1998

An elasto-plastic stochastic finite element method is developed to evaluate the probability of failure of the underground structure. The Mohr-Coulomb failure criteria is adopted for yield condition. The material properties such as the elastic modulus and the cohesion are assumed to be statistically independent random variables which are modeled as spatial stochastic fields. The displacements around the excavated area and the probability of the failure are examined by varying the coefficient of variance for each variables. It is found that the developed procedure can provide the proper probabilistic information about the failure of the underground structure

• Electrical & Electronic Materials
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• v.9 no.10
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• pp.1033-1039
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• 1996

Electrical and mechanical properties of polymer sheet at cryogenic temperature have been investigated. Tensile stress(and strain at break) in liquid nitrogen(77K) of 79.7MPa(l.2%) and 117.4MPa(2.05%) are evaluated for films of Polypropylene (PP) and Kapton, respectively. Dielectric loss tangent(tan .delta.) of PP and Kapton films is almost independent of the frequency and tensile stress. Also, field strength of PP film at 77K decreases with increasing the tensile stress.

• Journal of the Korean Society of Safety
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• v.11 no.2
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• pp.9-15
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• 1996

The characteristics on the extension of the CED(Crack energy density) concept to the interface kinked crack problems in a dissimilar material are examined. Each mode contributions of CED are found by symmetric and antisymmetric components and domain independent integrals. Finite element calculation is carried out to simulate the Interface kinked crack growth on bimaterial. The focus is the establishment of fracture criterion with CED and finding the orientation of crack extension. From the results, a prediction about the extension behavior of an interface kinked crack can be done. And we show that CED can be a parameter to indicate fracture criterion at an Interface kinked crack.

• Geomechanics and Engineering
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• v.37 no.5
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• pp.453-465
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• 2024

This paper presents a logarithmic shear deformation theory to study the thermal buckling response of power-law FG one-dimensional structures in thermal conditions with different boundary conditions. It is assumed that the functionally graded material and thermal properties are supposed to vary smoothly according to a contentious function across the vertical direction of the beams. A P-FG type function is employed to describe the volume fraction of material and thermal properties of the graded (1D) beam. The Ritz model is employed to solve the thermal buckling problems in immovable boundary conditions. The outcomes of the stability analysis of FG beams with temperature-dependent and independent properties are presented. The effects of the thermal loading are considered with three forms of rising: nonlinear, linear and uniform. Numerical results are obtained employing the present logarithmic theory and are verified by comparisons with the other models to check the accuracy of the developed theory. A parametric study was conducted to investigate the effects of various parameters on the critical thermal stability of P-FG beams. These parameters included support type, temperature fields, material distributions, side-to-thickness ratios, and temperature dependency.

• Advances in Traditional Medicine
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• v.5 no.4
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• pp.347-351
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• 2005

In the present investigation twelve indigenous medicinal plants have been screened for their antiimplantation activity in albino rats. The plant material was subjected for soxhlation successively and separately from non-polar solvents to polar solvents i.e., petroleum ether benzene and ethanol. Out of these three extracts the petroleum ether extract of seeds of Citrus medica, aerial part of Oxalis corniculata and Tinospora cardifolia have showed maximum antiimplantation activity. Ethanol extract of leaves of Cardiospermum helicacabum, roots of Echinops echinatus, leaves of Melia azedarach, seeds of Momordica charantia and bark of Terminalia bellirica have shown maximum antiimplantation activity amongst the three extracts of each plant material screened. Though all the three extracts of seeds of Annona squamosa and leaves of Zizyphus jujube screened for antiimplantation activity, no extract has showed any loss in implantation. The details of the results obtained are discussed.