• Journal of Auto-vehicle Safety Association
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• v.14 no.4
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• pp.21-26
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• 2022

Commercial use of autonomous vehicles is to come soon. So far most of responsibility of the accident is on the human driver with conventional vehicles whereas that will be on the car OEM and transportation related organizations with autonomous vehicles, which asks car OEM's and government to do vast study of car crash in various conditions. Test protocols need amendment and to be newly enacted to reflect new findings from the study aforementioned. Rigid stationary barrier and moving or stationary deformable barrier as well as car to car test which is same as actual accident can be utilized to simulate the crash happening on the road. Among those 3 test methods, rigid stationary barrier is most economic and has good repeatability. Limitation as well as advantage of the rigid stationary barrier is studied through comparison between car to car crash and oblique rigid barrier crash.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.5
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• pp.435-443
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• 2020

Thermal barrier coating(TBC) applied to fighter and turbine engines is a technology that improves the durability of core parts by lowering the surface temperature of base material. The thermal stress caused by mis-match of the coefficient of thermal expansion between the top coating and the TGO interface is the main cause of TBC breakage. Since the thermal stress is dependent on the microstructure of the TBC, designing microstructure of TBC can improve the durability as well as lower the thermal stress. In this study, the effect of coating thickness, volume of porosity and vertical cracking on the thermal stress was analyzed through finite element analysis. Through the analysis results, a design range of a microstructure that can improve the durability of thermal barrier coating by lowering thermal stress is proposed.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.195-205
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• 2001

The mechanical properties of aluminum honeycomb on the direction of axial crushing under quasistatic loading test was investigated. The crushing process was simulated numerically by full-scale finite element models. Simulations reproduce the experimental results both qualitatively as well as quantitatively. From the investigation, we suggested the constitutive model of energy absorbing honeycomb structure for large scale impact analysis. Real impact test of the WB(Moving Deformable Barrier) was carried and compared with finite element simulation. Constitutive model used in the numerical simulation had a good correlation with experiment. By suggesting the optimizing method fur honeycomb cell configuration design, relationship between cell configuration and crush strength is studied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2414-2418
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• 2014

This study carried out three-dimensional finite element analysis and structural safety evaluation of attachable roadside barriers. The effects of diaphragm distance and the number of bolts on displacements and maximum stresses for various parameters are studied using the LS-DYNA finite element program for this study. In this study, the existing finite element analysis of barriers using the LS-DYNA program is further extended to study static behaviors and structural safety of the barrier with module structures connected by anchor bolt inserted through concrete bridge decks. The numerical results for six parameters are verified by comparing different models with displacements and stress distribution occurred in the barrier and shows good structural performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.153-161
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• 2002

This paper develops a finite element model for crashworthiness analysis ova small-sized bus. The full vehicle finite element model is composed of 31,982 shell elements,599 beam elements,42 bar elements, and 34,204 nodes. The model uses four material models (such as elastic, elastic-plastic(steel), rigid. and elastic-plastic (rubber) material model) of PAM-CRASH. The model uses four contact types to define sliding interfaces in ten areas. A frontal crash test using an actual vehicle with 30mph velocity to a rigid barrier is carried out. Vehicle pulses at lower part of left and right b-pillar are measured, and deformed shapes of frame and driver seat's lower left area are photographed. A frontal crash simulation using the developed full vehicle finite element model is performed with PAM-CRASH installed in super computer SP2. The simulation is performed with the same conditions as the test. The measured vehicle pulses and photographed deformed shapes from the test are compared to ones from the simulation to validate the reliability of the developed model.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.601-603
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• 2002

This paper describes the design optimization of a 8:6 Switched Reluctance Motor(SRM) with the rotor pole inserted barrier. The design is focussed on the minimization of the static torque ripple as maintaining the average torque and the efficiency of the demanded value. The finite element analysis method (FEM) and the optimization algorithm are used to optimize the shape of the rotor pole. By comparing the FEM results of barrier type SRM with these of prototype, it is verified that the barrier type SRM improves the static torque characteristics.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.498-505
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• 2007

This paper proposes the novel flux barrier that built in q-axis in rotor of IPM type BLDC motor. The novel flux barrier aims to reduce the motor vibration with reduced cogging torque and lessened torque ripple by the sinusoidal waveform distribution of the flux generated in the permanent magnet. For optimization of the novel flux barrier, the Taguchi method is effectively employed which considered multiple objective quality characteristics, such as cogging torque, average torque and efficiency. The result of proposed model compare with the initial model and it is verified by 2D finite element method (FEM) results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1431-1434
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• 2014

The thermal barrier coating (TBC) applied to a gas turbine can be damaged by repeated thermal fatigue during operation, so an evaluation of its durability is needed. Thermally grown oxide (TGO) is generated inside the TBC in a high-temperature environment. The growth of TGO is known to be the main cause of damage to the TBC. Therefore, the durability of TBC should be evaluated according to the growth of TGO. In this research, Kim et al.'s work on the growth of TGO with aging was used as a basis for finite element analysis. The relationship between stress and aging was derived from the finite element analysis results. The durability of the TBC with aging was evaluated through a comparison between the results of the finite element analysis and a bond strength test.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.65-67
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• 2007

This paper proposes a novel flux barrier in q-axis of rotor in IPM type BLDC motor, The proposed flux barrier can reduce cogging torqeu and diminisg torque ripple by sinusoidal waveform distribution of flux generated in the permanent magnet. To determine the optimal shape of the novel flux barrier, we also propose a modified Taguchi method which considering multiple quality characteristics, such as cogging torque, average torque, and efficiency. The proposed design and method were analyzed by using the 2D finite element method (FEM). Results of the proposed model were compared with initial model.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.768-769
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• 2008

This paper examines an design of double-barrier rotor structure for improving the efficiency performance in a single-phase line-start permanent magnet(LSPM) motor. By utilizing the advantages of double-barrier rotor design that by increasing reluctance torque generation to compensate magnet torque production, the copper loss reduction is achieved. The optimal approach of response surface methodogy(RSM) is performed for determining a optimum double-barrier rotor structure. The improving of efficiency performance is confirmed by finite element method(FEM) and test.