• Structural Engineering and Mechanics
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• 제69권2호
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• pp.145-153
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• 2019

Modified couple stress formulation and first order shear deformation theory are used for magneto-electro-elastic bending analysis of three-layered curved size-dependent beam subjected to mechanical, magnetic and electrical loads. The governing equations are derived using a displacement field including radial and transverse displacements of middle surface and a rotation component. Size dependency is accounted based on modified couple stress theory by employing a small scale parameter. The numerical results are presented to study the influence of small scale parameter, initial electric and magnetic potentials and opening angle on the magneto-electro-elastic bending results of curved micro beam.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.220-223
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• 2003

This paper is aimed at determining the e-field distribution by apply voltage of air void, which can be generate air void in the XLPE cable for ultra high voltage. E-field distribution had an effect in XLPE due to the type and position of void, compared and studied. This method of analysis is based on the quasi-static electromagnetic 3D simulation program by boundary element method (BEM): Applied AC 3[kV], discretization of 2000 elements, 4 angular periodicity, The result of experiment indicate that E-field distribution appeared the highest levels on the void position of electrode 2[nm] outer boundary and shape of the smallest inner angle in the void. This will serve to explain the XLPE cable degradation studied of possible, connected cable variation of position and shape of void effects to e-field concentration.

• 환경생물
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• 제22권4호
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• pp.494-500
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• 2004

In order to investigate the effect on morphology of Rhizopus oryzae and production of lactic acid, various interface materials were used. Morphology of fungal showed sheet and flock when resin was added. The production of lactic acid was increased dramatically when interface materials were added. Furthermore, the effect of resin was more significant than that of others. It was assumed that interface materials could absorb substrate and microorganism together, so microorganism was not inhibited by substrate. The effect of static electric field on the interface culture was studied. When the exerting potential was 6.78 voltage, the biomass y was obviously higher than that of zero voltage. A simulated gas-solid interface system was developed to study the growth and two phases model for the growth of Rhizopus oryzae was build up that depended on the symmetric branching theory. An important parameter F was researched. The results indicated that the value of F had obvious difference at exponential and deceleration period, respectively.

• Steel and Composite Structures
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• 제31권5호
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• pp.469-488
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• 2019

We in this paper study nonlinear bending of a functionally graded porous nanobeam subjected to multiple physical load based on the nonlocal strain gradient theory. For more reasonable analysis of nanobeams made of porous functionally graded magneto-thermo-electro-elastic materials (PFGMTEEMs), both constituent materials and the porosity appear gradient distribution in the present expression of effective material properties, which is much more suitable to the actual compared with the conventional expression of effective material properties. Besides the displacement function regarding physical neutral surface is introduced to analyze mechanical behaviors of beams made of FGMs. Then we derive nonlinear governing equations of PFGMTEEMs beams using the principle of Hamilton. To obtain analytical solutions, a two-step perturbation method is developed in nonuniform electric field and magnetic field, and then we use it to solve nonlinear equations. Finally, the analytical solutions are utilized to perform a parametric analysis, where the effect of various physical parameters on static bending deformation of nanobeams are studied in detail, such as the nonlocal parameter, strain gradient parameter, the ratio of nonlocal parameter to strain gradient parameter, porosity volume fraction, material volume fraction index, temperature, initial magnetic potentials and external electric potentials.

• Smart Structures and Systems
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• 제18권1호
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• pp.139-154
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• 2016

This paper is concerned with the dynamics of hyperelastic solids and structures. We seek for a smart control actuation that produces a desired (prescribed) displacement field in the presence of transient imposed forces. In the literature, this problem is denoted as displacement tracking, or also as shape morphing problem. One talks about shape control, when the displacements to be tracked do vanish. In the present paper, it is assumed that the control actuation is provided by imposed eigenstrains, e.g., by the electric field in piezoelectric actuators, or by thermal actuators, or via analogous physical effects, such as magneto-striction or pre-stress. Structures with a controlled eigenstrain-type actuation belong to the class of smart structures. The action of the eigenstrains can be conveniently characterized by actuation stresses. Our theoretical derivations are performed in the framework of the theory of small incremental dynamic deformations superimposed upon a statically pre-deformed configuration of a hyperelastic solid or structure. We particularly ask for a distribution of incremental actuation stresses, such that the incremental displacements follow exactly a prescribed trajectory field, despite the imposed incremental forces are present. An exact solution of this problem is presented under the assumption that the actuation stresses can be tailored freely and applied everywhere within the body. Extending a Neumann-type solution strategy, it is shown that the actuation stresses due to the distributed control eigenstrains must satisfy certain quasi-static equilibrium conditions, where auxiliary body-forces and auxiliary surface tractions are to be taken into account. The latter auxiliary loading can be directly computed from the imposed forces and from the desired displacement field to be tracked. Hence, despite the problem is a dynamic one, a straightforward computation of proper actuator distributions can be obtained in the framework of quasi-static equilibrium conditions. Necessary conditions for the functioning of this concept are presented. Particularly, it must be required that the intermediate configuration is infinitesimally superstable. Previous results of our group for the case of shape control and displacement tracking in linear elastic structures are included as special cases. The high potential of the solution is demonstrated via Finite Element computations for an irregularly shaped four-corner plate in a state of plain strain.

• Journal of Platform Technology
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• 제12권1호
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• pp.119-127
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• 2024

본 논문에서는 아까시 종자의 발아율 향상을 위하여 종자의 외부적 자극으로 전자기장 에너지를 이용하였다. 전자기장 에너지는 모두 세 종류로 정자기장, 정전기장, 그리고 전자기장인 마이크로파가 있다. 정자기장 에너지를 건식방법으로 90분간 투과시킨 종자의 발아율은 대조군과 비교하여 10%이상 향상되었고, 정전기장 에너지 역시 건식방법으로 90분간 투과시킨 종자의 발아율은 20%이상 향상되었다. 또 전자기장 에너지로 2.45 GHz를 갖는 마이크로파 에너지를 습식방법으로 3분간 투과시킨 종자의 발아율은 25%이상 향상되었다. 실험결과 마이크로파를 투과시킨 종자에서 발아율이 가장 높고 그리고 새싹길이도 가장 크게 성장하였다. 결과적으로 본 논문에서는 마이크로파 에너지를 습식방법으로 종자에 투과시킴으로 종자의 발아율과 새싹 성장이 가장 우수하다는 것을 확인할 수 있다.

• 한국전자통신학회논문지
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• 제16권5호
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• pp.845-850
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• 2021

본 연구에서는 전기 자동차(EV : Electric Vehicle) 파워트레인의 에너지 변환 특성과 설계를 수행하였다. 그리고 EV 파워트레인의 동력원으로서 영구자석 매입형 동기 모터(IPMSM : Interior Permanent Magnet Synchronous Motor)를 대상으로 하였으며 제어를 수행하였다. IPMSM을 구동하기 위해서는 두 가지 영역인 일정한 토크와 일정한 출력(약계자) 영역이 사용되며, IPMSM을 위한 제어 시스템의 설계는 d-q 레퍼런스 프레임(벡터 제어)을 바탕으로 구성하였다. IPMSM의 두 영역에서 나타나는 모터 토크의 정적 특성을 결정하기 위해 IPMSM의 토크제어 시스템과 d축 전류 제어 시스템을 제안 및 구현하였다. 특성해석을 위해서 Matlab-Simulink 소프트웨어를 사용하였다. 최종적으로 실제 차량 사양을 기준으로 EV 차량 레벨 조건으로 변경하여 파워트레인 모델에 IPMSM을 적용하였으며 제안된 제어 시스템의 시뮬레이션 결과를 수행했고 특성을 분석하였다.

• 전력전자학회논문지
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• 제5권5호
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• pp.515-521
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• 2000

본 논문은 전동차용 추진장치인 IGBT VVVF 인버터의 현차시험에 관한 것이다. IGBT VVVF인버터는 1,650kVA급으로 개발되었다. 추진 인버터의 신뢰성과 성능을 확인하기 위하여 서울시 지하철 6호선에서 본선시험을 하였다. 시험 차량구성은 4M4T로 구성되었으며, 전장품은 4대의 VVVF인버터, 16대의 견인전동기 및 2대의 SIV로 구성하였다. 추진장치는 1C4M으로 구성하였다. 현차시험을 통하여 추진용 인버터의 우수한 가·감속 능력과 가가속도 특성 및 구배에서의 등판능력을 확인 할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.577-580
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• 2003

The magnetostriction of FeCoGe/phenol composites, which is one of the magnetostrictive materials, measured at the external magnetic field. The measurement was carried out using the electrical-resistance strain gage, the wheaten's Bridge for eliminating the unnecessary voltage, and the lock-in-amp for signal amplification and noise filtering. When the external magnetic field was applied in the longitudinal the samples, the maximum strain of 120ppm was taken with regard to the 10wt.% phenol composite. This results indicate that the FeCoGe/phenol composites can be useful as an actuator because it has larger stain than the other solid state actuators such as piezo electric materials.

• Steel and Composite Structures
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• 제46권4호
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• pp.485-495
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• 2023

Bending static and stress investigation of a microplate of piezoelectric/piezomagnetic material subjected to combined multifield loading. Shear deformable as well as thickness stretched model is used for derivation of the kinematic relations. Multi field governing equations are derived analytically through principle of virtual work. the results are analytically obtained analytically including magnetic/electric potentials, displacement and stress components with variation in multifield loading parameters.