• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.898-901
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• 2003

In order to get the drive reliability and low Power-consumption characteristics, most of small form factor HDD has und the load/unload mechanism instead of CSS type. Compared with CSS mechanism, the load/unload system has little opportunity of head/media contact during the disk spin-up and down. However, the load/unload mechanism needs the precise integration technology with slider, suspension, ramp and load/unload velocity, and all of these component s should be designed simultaneously, not an individually. In this paper, we focus the design of the suspension stiffness using the specified ABS design. We use the CML software to calculate the load/unload dynamic and use the RSM(Response surface method) to get the optimal condition of the suspension stiffness.

• ETRI Journal
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• v.41 no.4
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• pp.528-535
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• 2019

The coupling mechanism of a loop-type ground radiation antenna is investigated in this paper. We use the equivalent circuit model of the antenna and a full-wave simulation to explain the coupling mechanism of the antenna. We analyze the effects of various antenna parameters on the coupling between the antenna element and the ground plane to examine the conditions for enhancing the coupling. Based on simulations with the equivalent circuit model, full-wave simulations, and measurements, we propose optimal design considerations for the antenna. The findings of this study will aid the design and understanding of loop-type ground radiation antennas for mobile devices.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.2 s.257
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• pp.151-158
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• 2007

The mechanism of power transmission from motor torque to stem thrust and the operation characteristic of each stroke position are analyzed using the diagnostic signal, and effects of differential pressure on the performance of motor operated flexible wedge gate valve are investigated. Test facility consists of 76 mm motor operated valve(flexible wedge type), pump and pipe system. Static and dynamic test are performed separately, and two differential pressure conditions are applied in the dynamic test. To evaluate the performance of valve, test signals for the torque, thrust, current, voltage and stroke length are acquired by using UDS which is diagnosis device for motor operated valve, and each diagnostic signal is analyzed and compared. The characteristic of valve performance factors such as stem factor, rate of loading, valve factor, are evaluated, and these factors are found to be severely influenced by the fluid differential pressure.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.3
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• pp.76-81
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• 2002

In order to study the fatigue crack and retardation mechanism in variable loading, the effects of crack tip branching in crack growth retardation were examined. The characteristics of crack tip branching behavior were considered with respect to microstructure and crack tip branching angle was examined. Crack tip branching was observed along the grain boundary of finite and pearlite structure. It was found that the branching angle ranges from 25 to 53 degrees. Using the finite element method, the variable of crack driving farce to branching angle was examined. The effective crack driving farce (K$\_$eff/) decreased as the branching angle increased. The rate of decrease was 33% for kinked type and 29% for forked one. It was confirmed that the effect of crack tip branching is a very important factor in crack growth retardation. Therefore, crack branching effect should be considered in building the hypothetical model to predict crack growth retardation.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.301-306
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• 2001

In this paper, we developed a quadruped walking robot, FRAMIX-T, with insectile leg mechanism and we inspected the efficiency of it in detail. In robotics, the legs of insect type are appropriate for the stability and the agile movement. So we first performed a gait analysis using duty factor, stride, phase etc., and analyzed the stability margin to improve the stability of robot. On the basis of this research, we planned the wave gait suitable for FRAMIX-T and performed a walking experiment. From this result, we proved the high efficiency using insectile leg mechanism and the possibility of walking with improved stability and mobility.

• Journal of Applied Reliability
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• v.13 no.1
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• pp.65-76
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• 2013

In order to assess the reliability of engine mount for a vehicles, life test model and procedure are developed. By using this method, failure mechanism and life distribution are analyzed. The main results are as follows; i) the main failure mechanism is degradation failure of engine mount rubber by fatigue failure at dynamic load. ii) temperature is a second factor to affect a failure. iii) the life distribution of engine mount module is fitted well to Weibull life distribution and the shape parameter is 18.4 and the accelerated life model of that is fitted well to Arrhenius model.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.7
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• pp.279-286
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• 2002

Linear and nonlinear complex permittivities were measured for copolymers of vinylidene cyanide(VDCN) with vinyl acetate(VAc), vinyl propionate(VPr), vinyl bezoate(VBz), styrene(St) and methyl methacrylate(MMA). Experimental results are well fitted by the function (equation omitted) except at low frequency where dc conduction dominates. The analysis of dielectric relaxation mechanism by combined knowledge about linear and nonlinear dielectric permittivities and dipoles give us informations about electrical and thermal motions in these copolymers. According to the analysis it could be found that the variation for temperature of the dielectric relaxation strength in these copolymers is related to the interaction between dipoles and the nonlinear dielectric effect factor R$_{s}$ is proportional to square of the dipolar correlation factor R$_{p}$././.

• Earthquakes and Structures
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• v.14 no.6
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• pp.537-549
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• 2018

Using vertical links in eccentric braced frames is one of the best passive structural control approaches due to its effectiveness and practicality advantages. However, in spite of the subject importance there are limited studies which evaluate the seismic reliability and response reduction factor (R-factor) in this system. Therefore, the present study has been conducted to improve the current understanding about failure mechanism in the structural systems equipped with vertical links. For this purpose, following definition of demand and capacity response reduction factors, these parameters are computed for three different buildings (4, 8 and 12 stories) equipped with this system. In this regards, pushover and incremental dynamic analysis have been employed, and seismic reliability as well as multi-level response reduction factor according to the seismic demand and capacity of the frames have been derived. Based on the results, this system demonstrates high ductility and seismic energy dissipation capacity, and using the response reduction factor as high as 8 also provides acceptable reliability for the frame in the moderate and high earthquake intensities. This system can be used in original buildings as lateral load resisting system in addition to seismic rehabilitation of the existing buildings.

• Solar Energy
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• v.7 no.1
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• pp.35-41
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• 1987

This paper presents a comprehensive computer simulation of hydrogenated amorphous p-i-n silicon solar cells. The physical mechanism governing solar cell operation has been modeled and solved numerically by Runge-Kutta-Gill method. Effects of gap state density, dopant impurity, diffusion length and interface recombination velocity on solar cell performance are investigated. Numerical results show that the electric field in i-region is not uniform but depends strongly on voltage and position. A rather poor fill factor may be due to the electric field variation and short diffusion length. It is found out that the life time should be improved in order to increase a fill factor and a conversion efficiency.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1667-1672
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• 2007

In order to assess the reliability of the exhaust bellows for automobiles, accelerated life test model and procedure are developed. By using this method, failure mechanism and life distribution are analyzed. The main results are as follows; i) the main failure mechanism is crack or breakage of inner flexible tube by shaken displacement at shear direction. ii) temperature is a second factor to affect a failure. iii) the life distribution of exhaust bellows is fitted well to Weibull life distribution and the shape parameter is 13.3 on condition of shaken displacement and $600^{\circ}C$