• 한국자동차공학회논문집
• /
• 제12권4호
• /
• pp.74-84
• /
• 2004

In this paper, a theoretical method was derived to redesign carbody members by substituting light-weight materials, and to estimate their structural characteristics. Some performance indices to estimate structural behaviors were derived in order to obtain equivalent designs in case of material substitutions under important design constraints of rolling stock, such as bending stiffness, natural frequency, bending and buckling strength. Validity of the theoretical method was evaluated by comparing its results with finite element results in some examples where the aluminium alloy was substituted for the structural steel. The numerical results of the examples show that the proposed method gives reasonable initial guesses for the material substitution designs.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 추계학술대회 논문집
• /
• pp.812-815
• /
• 2002

The shape of K-R curve for an ideally brittle material is flat because the surface energy is an unvaried material property. However, the K-R curve can take on a variety of shapes when nonlinear material behavior accompanies fracture. By the way, a general metallic material is nonlinear, structural steel is such. Therefore, the J-R curve form J-integral value instead of K parameters can be used to evaluate elastic-plastic materials with flaws in terms of ductile fracture that can be significant to design. In this paper, R-curve behaviors form K and J parameter is considered for the precise assessment of fracture analysis, in case of JS-SS400 steels.

• Advances in materials Research
• /
• 제8권3호
• /
• pp.179-196
• /
• 2019

This paper researches static and dynamic bending behaviors of a crystalline nano-size shell having pores and grains in the framework of strain gradient elasticity. Thus, the nanoshell is made of a multi-phase porous material for which all material properties on dependent on the size of grains. Also, in order to take into account small size effects much accurately, the surface energies related to grains and pores have been considered. In order to take into account all aforementioned factors, a micro-mechanical procedure has been applied for describing material properties of the nanoshell. A numerical trend is implemented to solve the governing equations and derive static and dynamic deflections. It will be proved that the static and dynamic deflections of the crystalline nanoshell rely on pore size, grain size, pore percentage, load location and strain gradient coefficient.

• Journal of Magnetics
• /
• 제5권3호
• /
• pp.102-105
• /
• 2000

The extremely soft magnetic behaviors in the nanocrystalline $Fe_81B_11Nb_7Cu_1$ alloy annealed at 450 $\circ C$ and 550 $\circ C$ for 1 hour in a vacuum were investigated by means of the magnetoimpedance (MI) effect and the incremental permeability. Because the MI effect can be obtained only in ultra-soft magnetic materials, the improvement of magnetic softness by proper thermal treatment was carefully monitored by the MI effect for all annealed samples. The changes of the incremental permeability as a function of an external field were also measured to verify the magnetic softness along with the MI measurement.

• Structural Engineering and Mechanics
• /
• 제40권1호
• /
• pp.49-64
• /
• 2011

An analytical method is presented to investigate electromagnetothermoelastic behaviors of a hollow sphere composed of functionally graded piezoelectric material (FGPM), placed in a uniform magnetic field, subjected to electric, thermal and mechanical loads. For the case that material properties obey an identical power law in the radial direction of the FGPM hollow sphere, exact solutions for electric displacement, stresses, electric potential and perturbation of magnetic field vector in the FGPM hollow sphere are determined by using the infinitesimal theory of electromagnetothermoelasticity. Some useful discussion and numerical examples are presented to show the significant influence of material inhomogeneity. The aim of this research is to understand the effect of composition on electromagnetothermoelastic stresses and to design optimum FGPM hollow spheres.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2003년도 추계학술대회 논문집(III)
• /
• pp.446-454
• /
• 2003

This paper derived a theoretical method to estimate structural characteristics of carbody members when material substitution designs were performed, and verified the theoretical method with finite element analyses. For important factors in rolling stock design, such as bending stiffness, natural frequency, bending strength and buckling strength, some performance indices to estimate structural behaviors were developed in order to derive an equivalent design in spite of material substitutions. The developed method was used to reduce the weights of carbody components, as example problems, by substituting the aluminium alloy for the structural steel. The analysis results of the examples show that the proposed technique gives a reasonable initial guess in the case of a material substitution design.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
• /
• pp.466-472
• /
• 2000

The extremely soft magnetic behaviors in the nanocrystalline Fe$_{81}$B$_{11}$Nb$_{7}$Cu$_{1}$ alloy annealed at 450 $^{\circ}C$ and 550 $^{\circ}C$ for 1 hour respectively in a vacuum were obtained, and examined by means of the magnetoimpedance(MI) effect and the incremental permeability. Because the MI effect can be obtained only in ultra-soft magnetic materials, the improvement of magnetic softness by proper thermal treatment was carefully monitored by the MI effect for all annealed samples. The changes of the incremental permeability as a function of an external field were also measured to verify the magnetic softness along with the MI measurement.ent.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
• /
• pp.127-128
• /
• 2005

UV-curable pressure sensitive adhesives were prepared by blending acrylic copolymer, copolymerized with butyl acrylate (BA), acrylic acid (AA) and vinyl acetate (VAc) by solution polymerization, triethyl amine (TEA) and trimethylolpropane triacrylate (TMPTA). The PSAs were evaluated by peel strength with varying contents of TMPTA and UV dose, and also glass transition temperature($T_g$) of PSAs were measured. When exposed on UV irradiation, the PSAs showed the decreased peel strength and increased $T_g$. And following UV irradiation, the PSAs did not leave any residue on wafer after peel off PSA.

• Geomechanics and Engineering
• /
• 제35권2호
• /
• pp.181-194
• /
• 2023

The primary objective of this study is to examine the influence of geometry on the stability characteristics of cylindrical microstructures. This investigation entails a stability analysis of a bi-directional functionally graded (BD-FG) cylindrical imperfect concrete beam, focusing on the impact of geometry. Both the first-order shear deformation beam theory and the modified coupled stress theory are employed to explore the buckling and dynamic behaviors of the structure. The cylinder-shaped imperfect beam is constructed using a porosity-dependent functionally graded (FG) concrete material, wherein diverse porosity voids and material distributions are incorporated along the radial axis of the beam. The radius functions are considered in both uniform and nonuniform variations, reflecting their alterations along the length of the beam. The combination of these characteristics leads to the creation of BD-FG configurations. In order to enable the assessment of stability using energy principles, a numerical technique is utilized to formulate the equations for partial derivatives (PDEs).

• 한국유통학회:학술대회논문집
• /
• 한국유통학회 2007년도 하계통합학술대회 발표논문집
• /
• pp.3-26
• /
• 2007

최근 영역초월행동에 관한 관심이 늘어나고 있다. 여기서 영역초월행동은 종업원들이 사전에 정해진 역할을 넘어서 추가적으로 수행하는 행동을 의미하는데, 영역초월행동은 고객의 만족과 서비스 품질지각, 그리고 호의적인 구전활동을 강화하는데 중요한 역할을 한다. 그러나 영역초월행동이 중요한 역할을 할 것으로 기대할 수 있는 기업 간 거래관계, 특히 유통경로 구성원간 관계에서 영역초월행동에 관한 연구는 국내는 물론 해외에서도 매우 부족한 실정이라 할 수 있다. 이에 본 연구에서는 기존에 서비스 분야에서 주로 다루어졌던 영역초월행동을 유통경로 조직간 관계에서 다루었다. 특히, 본 연구는 다양한 유통경로의 조직패턴, 즉, 기업형, 계약형, 그리고 전통형 유통경로별로 영역초월행동이 어떻게 다르게 나타나는 지도 탐험적으로 살펴보았다. 자동차 대리점 200점, 외식 프랜차이즈 가맹점 120점, 산업자재 소매점 104점, 총 420개의 소매점을 대상으로 실시한 설문조사 결과 판매자의 의사소통의 질, 공정성, 마케팅 프로그램의 일관성이 구매자의 관계만족과 조직결속을 통해 영역초월행동을 강화하는 것으로 나타났다. 한편, 영역초월행동은 수직적 통합수준이 높은 계약형과 기업형 경로구조에서 더 활발하게 나타났다.