• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1989.06a
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• pp.49-51
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• 1989

The effect of Mo elenent and annealing condition on the magnetic properties were investigated in Fe$_{80}$B$_{12}$Si$_{8}$ amorphous alloy. With increasing Mo contents, soft magnetic properties were improved by decreasing coercive force and increasing maximum permeability. These improvements were attributed to the decreasing of magnetostriction by Mo addition. The annealing treatment also improved the soft magnetic properties of (Fe$_{1-x}$ Mo$_{x}$)$_{80}$ B$_{12}$ Si$_{8}$ amorphous alloys. It could be thought that these improvements were ascribed to the relaxation of internal stress.nal stress.ess.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.4
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• pp.64-75
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• 1991

The design of structures of modern industry has developed to satisfy stringent service, realiability and safety. Up to now, geometric profile which means surface foughness and dimension accuracy is mainly treated in manufacturing process of work surface. But it is inevitable to evaluate changes of surface geometry as well as the nature of alterations in surface layers because surface of workpiece changes as a result of phase transformation, chemical changes, plastic deformation and stress changes. This paper is to present principal data for safety design by verifying the effect of grinding conditions and method in grinding layers and to explain the method of measuring surface integrity. In this paper, structural steel(SM20C) is used as a workpiece. Of integrity, surface roughness in view of surface texture is analyzed by frequency domain and residual stress, structures and defect of ground layers in view of surface metallurgy are investigated.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.123-130
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• 2002

The ground-borne vibration from pile driving is causing many public discontents. However, because of the fact that the characteristics of wave propagation and attenuation are not well understood, systematic and effective vibration reduction measures can not be taken. This paper attempts to study the propagation of stress waves induced by the pile driving. To simulate the wave propagation in a semi-infinite domain, the so-called absorbing boundaries are incorporated in the finite element method and a series of numerical simulations is performed. Numerical results show that the surface displacement and velocity increase first and then decrease as the pile penetration depth becomes larges.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.162-162
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• 2005

• Journal of Ocean Engineering and Technology
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• v.34 no.2
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• pp.120-127
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• 2020

Evaluation of fatigue strength considering the springing effect of very large container ships is crucial in the design stage. In this study, we established a fatigue strength evaluation method considering a linear springing component in the frequency domain. Based on a three-dimensional global model, a fluid-structure interaction analysis was performed and the modal superposition method was applied to determine the hot spot stress at the hatch corner of very large container ships. Fatigue damage was directly estimated using the stress transfer function with a linear springing response. Furthermore, we proposed a new methodology to apply the springing effect to fatigue damage using hull girder loads. Subsequently, we estimated the fatigue damage contribution due to linear springing components along the ship length. Finally, we discussed the practical application of the proposed methods.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.10
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• pp.1613-1620
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• 2001

This study is focused on the application of the homogenization design method (HDM) to reduce the vibration level of a structure excited by magnetic harmonic farces. This is accomplished by obtaining the optimal material distribution in a design domain to minimize the frequency response caused by the magnetic harmonic excitation. The Maxwell stress method is used to compute the magnetic force and the HDM is applied leer the optimization. The developed method is applied to a simple pole model that is excited by the harmonic bending farce caused by the current around an adjacent stator. Results shows that the HDM is valid to minimize the frequency response.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.1 s.106
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• pp.3-11
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• 2006

This paper presents a new approach for hysteresis modeling of a magnetorheological (MR) fluid. The field-dependent hysteresis of MR fluid is investigated using the Preisach model. The commercial MR product (MRF-132LD, Lord Corporation) is employed. Its field-dependent shear stress is then obtained using a rheometer (MCR 300, Physica). In order to show the applicability of the Preisach model to the MR fluid, two significant properties; the minor loop property and the wiping-out. property are experimentally examined. Subsequently, the Preisach model for the MR fluid is identified using experimental first order descending (FOD) curves in discrete manner. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one. In addition, the hysteresis model proposed in this work is compared to Bingham model.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.9
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• pp.934-943
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• 1990

There are no turn-on losses in the series Resonant Converter which operates above the resonance frequency, and the commutation stress on the switched component is low. For a given Series Resonant Converter with specified load resistance, the output voltage is a function of the operation frequency. This paper describes the static and dynamic characteristic analysis of the Series Resonant DC to DC Converter, which is operating above the resonant frequency, with frequency control. For the analysis method, state plane technique is adopted, and the circuit operation is defined from normalized switching frequency, Fsn. Under this condition, circuit performance is analyzed ideally. The validity of the proposed analysis is verified by comparing with experimental results, the stability of the converter is confirmed against small variations around the operating point by conventional frequency domain analysis, and the stress quantity added to switch component is shown.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.1
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• pp.97-103
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• 2000

This paper deals with residual stresses induced at the viscoelastic adhesive layer between the semiconductor chip and the leadframe during adhesion process. The adhesive layer has been assumed to be“thermorheologically simple”. The time-domain boundary element method(BEM) has been employed to investigate the behavior of interface stresses. Numerical results show that very large stress gradients are present at the interface corner and such singularity might lead to local yielding or edge delamination.

• Honam Mathematical Journal
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• v.31 no.4
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• pp.579-590
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• 2009

The precise form of singular functions, singular function representation and the extraction form for the stress intensity factor play an important role in the singular function methods to deal with the domain singularities for the Poisson problems with most common boundary conditions, e.q. Dirichlet or Mixed boundary condition [2, 4]. In this paper we give an elementary step to get the singular functions of the solution for Poisson problem with Neumann boundary condition or Robin boundary condition. We also give singular function representation and the extraction form for the stress intensity with a result showing the number of singular functions depending on the boundary conditions.