• Title/Summary/Keyword: A356

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A Forward-Integrated Buck DC-DC Converter with Low Voltage Stress for High Step-Down Applications

  • Adivi, Maedeh Ghanbari;Yazdani, Mohammad Rouhollah
    • Journal of Power Electronics
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    • v.18 no.2
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    • pp.356-363
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    • 2018
  • The combination of a buck converter and a forward converter can be considered to accomplish a high step-down non-isolated converter. To decrease the insufficient step-down ratio of a regular buck converter and to distribute switch voltage stress, a forward-integrated buck (FIB) converter is proposed in this paper. The proposed interleaved DC-DC converter provides an additional step-down gain with the help of a forward converter. In addition to its simple structure, the transformer flux reset problem is solved and an additional magnetic core reset winding is not required. The operational principle and an analysis of the proposed FIB converter are presented and verified by experimental results obtained with a 240 W, 150 V/24 V prototype.

On some properties of vague bi-groups and fuzzy bi-functions (애매 bi-군과 퍼지 bi-함수의 성질에 관한 연구)

  • Jang, Lee-Chae;Kim, Tae-Kyun;Lee, Byung-Je;Kim, Won-Joo
    • Journal of the Korean Institute of Intelligent Systems
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    • v.20 no.3
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    • pp.356-361
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    • 2010
  • M. Demirci[Vague groups, J. math. Anal. Appl. vol.230, pp. 142-156, 1999] studied the vague group operation on a crisp set as a fuzzy function and estabished the vague group structure on a crisp set. In this paper we consider bi-groups which are studied by A.A.A. Agboola and L.S. Akinola. And we also will define vague bi-groups and fuzzy bi-functions and we investigate some basic operations on the vague bi-group and fuzzy bi-functions.

Energy based procedure to obtain target displacement of reinforced concrete structures

  • Massumi, A.;Monavari, B.
    • Structural Engineering and Mechanics
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    • v.48 no.5
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    • pp.681-695
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    • 2013
  • Performance-based seismic design allows a structure to develop inelastic response during earthquakes. This modern seismic design requires more clearly defined levels of inelastic response. The ultimate deformation of a structure without total collapse (target displacement) is used to obtain the inelastic deformation capacity (inelastic performance). The inelastic performance of a structure indicates its performance under excitation. In this study, a new energy-based method to obtain the target displacement for reinforced concrete frames under cyclic loading is proposed. Concrete structures were analyzed using nonlinear static (pushover) analysis and cyclic loading. Failure of structures under cyclic loading was controlled and the new method was tested to obtain target displacement. In this method, the capacity energy absorption of the structures for both pushover and cyclic analyses were considered to be equal. The results were compared with FEMA-356, which confirmed the accuracy of the proposed method.

Models for Social Media-Based Governments

  • Khan, Gohar Feroz
    • Asia pacific journal of information systems
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    • v.25 no.2
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    • pp.356-369
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    • 2015
  • Public sectors around the world utilize social media tools and technologies in their daily activities for a variety of purposes, including disseminating useful information, fostering mass collaboration, and enforcing laws and regulations. A number of social media-based government stage models have emerged to document this use. In this chapter, we conducted a qualitative meta-synthesis of four social media-based government models. These models include 1) the open government maturity model, 2) the social media utilization model, 3) the adoption process for social media, and 4) the social media-based engagement model. The concepts, metaphors, and themes contained in these developmental models are extracted through a series of in-depth semantic analyses of descriptions, resulting in a common frame of reference.

Navier-Stokes Computations of Supersonic Flow over Missile Afterbodies Containing a Centered Propulsive Jet (Navier-Stokes 방정식을 이용한 초음속 제트 추진 비행체 후방의 유동해석)

  • 윤병국;정명균
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.2
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    • pp.356-368
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    • 1992
  • The strongly interactive flow field near a missile afterbody containing a centered exhaust jet is numerically investigated. The thin shear layer and full formulation of compressible, Reynolds I averaged Navier-Stokes equations are solved. A time-dependent implicit numericals algorithm is used to obtain solution for a variety of flow conditions. Turbulence closure is implemented by the Baldwin-Lomax algebraic eddy viscosity model. An adaptive grid technique is adopted to resolve flow regimes with large gradients and to improve the accuracy and efficiency of the computation, Numerical results show good agreemement with experimental data in all regimes.

DOE approach in the FE Simulation of Liner Forging Process (실험계획법을 적용한 라이너 단조 공정의 유한요소해석)

  • Kim, Y.G.;Kang, G.P.;Seo, S.J.;Lee, J.K.;Yoon, T.S.;Lee, K.
    • Transactions of Materials Processing
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    • v.27 no.6
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    • pp.356-362
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    • 2018
  • A liner is a crucial component that directly affects the penetration performance of the shaped charge warhead. If the material of the liner has fine grain size and high strength, then the penetration performance can be further improved. There have been attempts to use a preform obtained by a severe plastic deformation (SPD) process. In this study, the process of minimizing the strain deviation to maintain the characteristics of material obtained by the severe plastic deformation process was investigated. The FE analysis of liner forging process was performed using the design of experiments (DOE), to optimize various shape parameters of the forming process such as shape of preform and forging die. As a result, the combination of design variables with the minimum effective strain deviation in the liner forging process were obtained.

Numerical and Experimental Study of Semi-solid A356 Aluminum Alloy in Rheo-Forging process

  • Kim, H.H.;Kang, C.G.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.10a
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    • pp.371-374
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    • 2009
  • Die casting process has been used widely for complex automotive products such as the knuckle, arm and etc. Generally, a part fabricated by casting has limited strength due to manufacturing defects by origin such as the dendrite structure and segregation. As an attempt to offer a solution to these problems, forging has been used as an alternative process. However, the forging process provides limited formability for complex shape products. Rheo-forging of metal offers not only superior mechanical strength but also requires significantly lower machine loads than solid forming processes. This paper presents the results of an A356 aluminum alloy sample, which were obtained by experiment and by simulation using DEFORM 3D. Samples of metal parts were subsequently fabricated by using hydraulic press machinery.

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Modeling and Analysis of Drift Error in a MSSG with Double Spherical Envelope Surfaces

  • Xin, Chaojun;Cai, Yuanwen;Ren, Yuan;Fan, Yahong
    • Journal of Magnetics
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    • v.21 no.3
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    • pp.356-363
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    • 2016
  • To improve the sensing accuracy of the newly developed magnetically suspended sensitive gyroscope (MSSG), it is necessary to analyze the causes of drift error. This paper build the models of disturbing torques generated by stator assembly errors based on the geometric construction of the MSSG with double spherical envelope surfaces, and further reveals the generation mechanism of the drift error. Then the drift error from a single stator magnetic pole is calculated quantitatively with the established model, and the key factors producing the drift error are further discussed. It is proposed that the main approaches in reducing the drift error are guaranteeing the rotor envelope surface to be an ideal spherical and improving the controlling precision of rotor displacement. The common problems associated in a gyroscope with a spherical rotor can be effectively resolved by the proposed method.

A Study on the Optimal Design of Mechanical Molding Press for Semiconductor Packaging (반도체 패키징용 기계식 프레스의 최적설계에 관한 연구)

  • Kim, Moon-Ki
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.22 no.3
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    • pp.356-363
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    • 2013
  • Mechanical molding press which is used for transformation process during semiconductor manufacturing process has structural deformations by pressure. If these deformations have over limit range, life of the press itself can be reduced and it will be exerted on a bad effect for quality of the semiconductor. In this research, the main plates and links of a press are analyzed in relation to the structural deformations caused by pressure excluding thermal deformations. After modifying the modeling, the analysis is performed again to determine optimal design of the press, and this design is introduced to ensure that most of the stresses on the main plates are within safe allowable limits. As a result, an optimal design method for the structure is investigated to produce the desired pressure even when the size of the main structure is minimized.