• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.4
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• pp.469-476
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• 2023

Soil plasticity models for cyclic and dynamic loads are essential in non-linear numerical analysis of geotechnical structures. While a single yield surface model shows a linear behavior for cyclic loads, J₂-bounding surface plasticity model with zero elastic region can effectively simulate a nonlinearity of the ground response with the same material properties. The radius of the yield surface inside the boundary surface converged to 0 to make the elastic region disappear, and plastic hardening modulus and dilatancy define plastic strain increment. This paper presents the stress-strain incremental equation of the developed model, and derives plastic hardening modulus for the hyperbolic model. The comparative analyses of the triaxial compression test and the shallow foundation under the cyclic load can show stable numerical convergence, consistency with the theoretical solution, and hysteresis behavior. In addition, plastic hardening modulus for the modified hyperbolic function is presented, and a methodology to estimate model variables conforming 1D equivalent linear model is proposed for numerical modeling of the multi-dimensional behavior of the ground.

• Journal of the Korean Geotechnical Society
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• v.27 no.2
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• pp.91-101
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• 2011

In this study, a new design method of Pile-Bent structure considering plastic hinge was proposed on the basis of the beam-column model. To obtain the detailed informations, the optimized cross-section ratio between column and pile was analyzed to induce the plastic hinge at the joint section between the pile and column. Base on this study, the optimized diameter ratio of pile and column can be obtained below the inflection point of the bi-linear curve depending on the relations between column-pile diameter ratio ($D_c/D_p$) and normalized lateral cracking load ratio ($F/F_{Dc=Dp}$). Moreover, through comparisons with field cases to find out in-depth limit in which minimum concrete-steel ratio could be applied, in-depth limits ($L_{As=0.4%}$) normalized by the pile length ($L_p$) proportionally decrease as the pile length ($L_p/D_p$)increases up to $L_p/D_p=17.5$, and beyond that in-depth limit converges to a constant value (${\simeq}0.3$).

• Electrical & Electronic Materials
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• v.6 no.5
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• pp.454-460
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• 1993

본 연구에서는 준강유전 특성을 갖는 xBa(L $a_{1}$2/N $b_{1}$2/) $O_{3}$- (1-x)Pb(Z $r_{y}$ $Ti_{1-y}$) $O_{3}$ (x=8.5, 9.0[mol.%], y=65, 70[mol.%]) 세라믹을 2단 소성법으로 제작한 후, 조성 및 인가전계에 따른 전기광학 특성 및 광변조 특성을 측정하였다. 인가전계가 증가함에 따라 8.5/65/35 시편을 제외한 전조성에서 유효복굴절이 2차 함수적으로 변화하는 2차 전기광학 특성을 나타내었으며 2차 전기광학계수, 반파장전압 및 ON-OFF ratio는 9.0/65/35 시편에서 각각 6.17x$10^{-16}$[ $m^{2}$/ $v^{2}$], 136[V], 252의 가장 우수한 값을 나타내었다. 9.0/70/30, 9.0/65/35 및 8.5/70/30 시편에 대해 광변조 특성을 측정한 결과, 입사광의 세기를 인가전압에 의해 변조시킬 수 있음을 관찰하였다.다.

• Electrical & Electronic Materials
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• v.8 no.1
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• pp.35-39
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• 1995

After making the light modulator using the BLN-PZT 9.0/65/35 specimen which has the slim-loop hysteresis characteristics and quadratic electro-optic characteristics, switching and spectral response characteristics were investigated. As the results of switching characteristics of the light modulator, it was found that the transmitted light intensity was modulated by both AC and pulse voltage. From the possibility of the selective transmission of the RGB(Red, Green, Blue) spectrum with electric field, the application for the light modulator, light shutter and color filter was expected.

• Journal of the Microelectronics and Packaging Society
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• v.2 no.1
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• pp.35-48
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• 1995

마이크로회로내에서 티탄산바륨 중 바륨의 일부가 납으로 치환됨에 따른 전기적 특 성의 변화를 확인하기 위하여 MOD(금속유기화합물 분해법)공정에 의 barum 2-ethylhexanoate, barium neodecanoate, lead 2-ethylhexanoate 및 titanium dimethoxy 야 -2-ethylhexanoate 와 같은 MOC(금속 유기화합물) 들을 합성하고 공통 용매에 대한 용해 도를 시험하였다. 그 결과 barium 2-ethylhexanoate 만 p-xylene에 대한 용해도가 낮았으며 그 외의 다른 MOC들은 모두 p-xylene 단일 용매에 매우 잘 용해되었다. 바륨의 일부가 납 으로 치환된 티탄산 납바륨 박막은 MOC 혼합용액을 ITO/glass, Pt/SiO2/Si 및 Pt/Ti/SiO2/Si 웨이퍼 기판 위에 spin coating 하고 소성하여 얻었다. 이와 같이 얻어진 박막 의 전기적 특성을 측정하고 그 결과를 비교 고찰하였다.

• Transactions of Materials Processing
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• v.5 no.2
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• pp.105-114
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• 1996

Recently, precision forging techniques are applied to manufacture spur gears. Compared to conventional machining, they produce parts of better mechanical properties and less residual stresses with a much higher production rate. In the present investigation a rigid-plastic three dimensional finite element method was applied to analyze hot forging and cold sizing of a spur gear by closed dies. The involute curve of a tooth profile was approximated by a circle close to the curve. Results of the analyses make it possible to predict local strengths of the gear die failure and an appropriate preform for cold sizing. It was found that the preform for cold sizing. It was found that the preform for the cold sizing is the most important because it determines whether the gears especially teeth can be successfully formed.

• Electrical & Electronic Materials
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• v.8 no.2
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• pp.190-195
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• 1995

Temperature dependences of the dielectric constant K(T), remanent polarization $P_{r}$, (T), effective birefringence overbar .DELTA.n(T), transmitted light intensity and quadratic electro optic coefficient R(T) of the two-stage sintered xBa(L $a_{1}$2/N $b_{1}$2/) $O_{3}$-(1-x)Pb(Z $r_{y}$ $Ti_{1-y}$) $O_{3}$(x=0.085, 0.09, 0.40.leq.y.leq.0.70) ceramics were investigated. Increasing the PbZr $O_{3}$ contents, the crystal structure of a specimen was changed from a tetragonal phase to a rhombohedral and cubic phase, and the phase transition was showed a diffuse phase transition(DPT) characteristics. In the compositions which located on the PE-FE phase boundary, the discrepancy was observed between the Curie temperature and temperature which a microscopic polarization and effective birefringence were disappeared.red.d.

• Electrical & Electronic Materials
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• v.6 no.3
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• pp.241-247
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• 1993

본 연구에서는 투광성 0.085Ba(L $a_{1}$2/N $b_{1}$2/) $O_{3}$- 0.915Pb(Z $r_{y}$ $Ti_{1-y}$) $O_{3}$(0.45.leq.y.leq.0.70)세라믹을 2단 소성법으로 제작한 후, PbZr $O_{3}$조성 및 온도에 따른 구조적, 강유전적특성을 측정하였다. XRD측정 결과, PbZr $O_{3}$조성이 감소할수록 결자상수 및 단위격자 체적은 감소하였으며 시편의 결정구조는 입방정계에서 능면체정계, 정방정계로 변화되었다. 8.5/60/40시편의 경우 포화분극, 잔류분극 및 항전계가 각각 33.28[.mu.C/$cm^{2}$], 4.15[kV/cm]로 전형적인 메모리 특성을 나타내었으며 PbZr $O_{3}$조성이 증가함에 따라 강유전 이력곡선은 slim loop특성을 나타내었다. 잔류분극은 온도가 증가함에 따라 감소하였으며 특히 PE-FE상경계 부근에 위치한 조성의 경우, 상전이 온도 이하의 온도에서 급격히 감소하는 경향을 나타내었다.다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.5
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• pp.653-660
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• 1986

Two uppor bound solutions, by the force balance method and by a kinematically admissible velocity field, are compared for the metal forming problems in plane strain. It is concluded that these two approaches always give identical results when the geometrical configurations of the deformation model reman the same. By detailed derivations for plastic bending of a notched bar, closed die forging, compression of a rectangular block, machining with a restricted contact tool and plane strain backward extrusion, the identity of both approaches is verified.

• Journal of Ocean Engineering and Technology
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• v.2 no.1
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• pp.90-94
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• 1988

본 논문은 반 잠수식 시추선과 선박과의 충돌해석에의 정적 압축법의 응용에 대해 다루었다. 선박이 시추선의 취약 부재에 충돌하는 경우를 가정하였으며 이 취약한 부재의 충돌에너지 흡수능력을 상세 해석 없이 추출하는 방법으로, 관련된 구조물 전체 강성 매트릭스를 부재의 양단에 정적 압축을 시켜 양단 유연도를 추출한 뒤 이 유연도를 양단에 가진 원통형 부재를 해석함으로써 외력-변형 관계를 얻을수 있었다. 충돌에너지 양은 외력-변형 선도를 적분함으로써 얻을 수 있다. 새로운 방법에 의한 결과를 3차원 수치해석 방법과 강체 프라스틱 방법에 의해서 얻어진 결과와 상호 비교하였으며, 이 새로운 방법이 해양구조물 충돌해석이 매우 효과적으로 응용될 수 있음을 알게 되었다.