• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.54-59
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• 2014

The rapid tactical operation and mobility are getting important to recently developed the guided weapon systems. And military wants multi-purposes equipment to carry the war more easily. So military wants to have the equipment that can apply without any distinction about environment. For this reason, the robust design is getting more important now to guarantee survivability of equipment. In this paper, we try to check about structural integrity of Fire Control Unit(FCU) which is one of the guided weapon system using dynamic FEM analysis.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.198-204
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• 2004

Dynamic fracture is investigated in plate applied by impacting bar. Numerical simulations of the experiments are made by using a finite element method(FEM) code, LS-DYNA. The eroding surface-to-surface contact allows between impacting bar and impacted plate. The occurrence of hourglass deformations in an analysis can invalidate results and hourglass energy is minimized to obtain the good accuracy of result. Total, internal and kinetic energies, von Mises plastic stress and X,Y,Z velocities of impacting bar are analyzed in this study.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.85-87
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• 2008

This paper presents dynamic characteristics in Switched Reluctance Motor (SRM) with rotor eccentricity and proposes the reduction method of rotor eccentricity effects by the different winding connections. These characteristics investigations are computed by 2D transient magnetic FEM analysis coupled with external circuits. The radial and unbalance magnetic force in the stator, which is the main exciting force of the vibration, is calculated using Maxwell stress method and compared with the performance characteristics according to the serial and parallel connections of windings. The influence of winding method counteracting unbalance forces on the rotor vibration behavior is estimated by the current waveforms of the paralleled paths under rotor eccentricity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.974-981
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• 2012

This paper studied about the measurement method of the instantaneous dynamic load characteristics. this experimental study, we derived the instantaneous washing load characteristics and inertial moment characteristics according to the amount of laundry and water level. Also, this studied about the dynamic driving characteristics simulation method for the prediction of washing performance based on this load characteristics analysis. For this study, the design parameters of the driving motor are obtained by FEM analysis and the experiment. By using theses motor parameters and load characteristics, the instantaneous driving characteristics simulation is accomplished and it is verified with the experimental result of various driving conditions. The results of this paper would be very useful to the prediction of washing mode operation characteristics, and it can be also utilized to the washer motor control algorithm design for the washing performance improvement.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.3 s.120
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• pp.220-225
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• 2007

Free vibration analysis using the method of NDIF (non-dimensional dynamic influence function), which was developed by the author, is extended to arbitrarily shaped polygonal plates with free edges. Local Cartesian coordinate systems are employed to apply the free boundary condition to nodes distributed along the edges of the plate of interest. Furthermore, a new way for applying the free boundary condition to nodes located at corners of the plate is for the first time introduced by considering the phenomenon of stress concentration at the corners. Two case studies show that the proposed method is valid and accurate when the eigenvalues by the proposed method are compared to those by FEM(ANSYS).

• Nuclear Engineering and Technology
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• v.53 no.8
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• pp.2696-2707
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• 2021

The purpose of this study is to investigate the efficiency of various structural modeling schemes for evaluating seismic performances and fragility of the reactor containment building (RCB) structure in the advanced power reactor 1400 (APR1400) nuclear power plant (NPP). Four structural modeling schemes, i.e. lumped-mass stick model (LMSM), solid-based finite element model (Solid FEM), multi-layer shell model (MLSM), and beam-truss model (BTM), are developed to simulate the seismic behaviors of the containment structure. A full three-dimensional finite element model (full 3D FEM) is additionally constructed to verify the previous numerical models. A set of input ground motions with response spectra matching to the US NRC 1.60 design spectrum is generated to perform linear and nonlinear time-history analyses. Floor response spectra (FRS) and floor displacements are obtained at the different elevations of the structure since they are critical outputs for evaluating the seismic vulnerability of RCB and secondary components. The results show that the difference in seismic responses between linear and nonlinear analyses gets larger as an earthquake intensity increases. It is observed that the linear analysis underestimates floor displacements while it overestimates floor accelerations. Moreover, a systematic assessment of the capability and efficiency of each structural model is presented thoroughly. MLSM can be an alternative approach to a full 3D FEM, which is complicated in modeling and extremely time-consuming in dynamic analyses. Specifically, BTM is recommended as the optimal model for evaluating the nonlinear seismic performance of NPP structures. Thereafter, linear and nonlinear BTM are employed in a series of time-history analyses to develop fragility curves of RCB for different damage states. It is shown that the linear analysis underestimates the probability of damage of RCB at a given earthquake intensity when compared to the nonlinear analysis. The nonlinear analysis approach is highly suggested for assessing the vulnerability of NPP structures.

• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.217-225
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• 2009

Recently, intensive research efforts are world-widely forced on the development of sport shoes improving both the injury protection and the playing performance by taking kinesiology and biomechanics into consideration. However, the success of this goal depends definitely on the reliable evaluation of the dynamic responses of sport shoes and human foot, particularly the landing impact characteristics. It is because the landing impact force is a main source of unexpected injuries and influences the playing performance in court sport activities. This paper addresses the application of finite element method to the evaluation of landing impact characteristics of barefoot and several representative court sport shoes in running. In order to accurately reflect the coupling effect between human foot and shoes accurately, we construct a fully coupled three-diemensional foot-shoe FEM model which does not rely on the independent experimental data any more. Through the numerical simulation, we assessed the reliability of the numerical FEM model by comparing with the experimental results and investigated the landing impact characteristics, such as GRF, MIF, acceleration and frequency responses, of representative court sport shoes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.236-240
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• 2005

This paper deals with friction-induced vibration of disc brake system under constact friction coefficient. A linear, finite element model to represent the floating caliper disc brake system is proposed. The complex eigenvalues are used to investigate the dynamic stability and in order to verify simulations which are based on the FEM model, The comparison of experimental and analytical results shows a good agreement and the analysis indicates that mode coupling due to friction force and geometric instability is responsible fur disc brake squeal. And the Front brake system reduced the squeal noise using design of experiment method(DOE). This helped to validate the FEM model and establish confidence in the simulation results. Also they may be useful during real disk brake model.

• Explosives and Blasting
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• v.14 no.2
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• pp.71-80
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• 1996

A series of nurmerical analysse for the earhtquake of Iran railway tunnles under construction by NATM(New Astrian Tunnelling Method) were careid out throuth a pseudo-dynamic analyses techique used in a FFM computer program, DWTAP(Daewoo Tunnel Analysis Program), and the results are described in the paper. The analyses were performErl for two case;one is for the primary supports and the other is for the rompletEd permanent roncrete lining. The horizontal and verical groW1d accelerations for the design were estimatEd as 0.34 g and 0.23 g, respectively based on the historical reismic rerords in the proj3et area and the empirical equations. The results show that the turmel would be safe W1der the anticipitOO earthquake motion with the permanent roncrete lining, but some minor cracks rnigt be developErl in the primary shotcrete lining without any significant structural damages.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.882-887
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• 2003

This paper presented a design and control of a new RGO(reciprocating gait orthosis)and its simulation. The new RGO was distinguished from the other one by which had a very light-weight and a new RGO(reciprocating gait orthosis) system. The vibration evaluation of the hip joint system on the new RGO(reciprocating gait orthosis)was used to access by the 3-axis accelerometer with a low frequency vibration of less than 30 ㎐. The gait of the new RGO depended on the constrains of mechanical kinematics and the initial posture. The stability of dynamic walking was investigated by analyzing the ZMP (zero moment point) of the new RGO. It was designed according to the human wear type and was able to accomodate itself to the environments of S.C.I. Patients. The joints of each leg were adopted with a good kinematic characteristics. To analyse joint kinematic properties, we made the hip joint system of FEM and the hip joint system by 1-axis and 3-axis Accelerometers.