• Transactions of Materials Processing
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• v.26 no.3
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• pp.144-149
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• 2017

In order to characterize the macroscopic mechanical response of ultra-thin (0.1 mm thick) ferritic stainless steel sheet at various loading paths, a crystal plasticity finite element method (CP-FEM) was introduced. The accuracy of the prediction results was validated by comparing with the experimental data. Based on the results, the forming limit diagram (FLD) was predicted using a modified Marchinicak-Kuczinski model coupled to a non-quadratic anisotropic yield function, namely, Yld2000-2d. The predicted FLD was found to be in good agreement with the experimental data.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.2
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• pp.67-75
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• 2004

This study aims to investigate the dynamic behaviour of a parabolic arch with initial deflection by using the elasto-plastic finite element model where the von-Mises yield criteria have been adopted. The initial deflection of arch was assumed by the high order polynomial of ${\omega}_i$ = ${\omega}_o$${(1-{(2x/L)}^m)}^n$) and the sinusoidal profile of ${\omega}_i$ = ${\omega}_o$$\sin$(n$\pi$x/L). Several numerical examples were tested considering symmetric initial deflection modes when the maximum initial deflection of an arch is fixed as L/500, L/1000, L/2000 or L/5000. The effects of polynomials order on the dynamic behavior of arch were not conspicuous. The most unfavorite dynamic response occurs when the maximum initial deflection varies from L/1000 to L/4000 if the initial deflection mode is represented by high order polynomials.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.1
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• pp.54-62
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• 2000

The purpose of this study is to bring out the optimal design factors which effect on dynamic characteristics in the design of flow control servo valve with high response characteristics, and to verify the validity of the design factors. In this study, force feedback type flow control valve with nozzle/flapper and with no drain is studied. And, the effect of the parameters, such as fixed orifice, nozzle diameter, and maximum displacement between nozzle and flapper are analyzed. We have done simulations using the optimal design factors and simulink(Matlab) as a simulation tool, and verified the validity of our simulations by means of comparison our simulation results with an experimental results of another similar valve.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.86-87
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• 2000

Chitosan (deacetylated form of chitin) possesses strong antibacterial activities such as antimicrobial effect, antifungal effect and the induction of plant defense response. Chitosan itself, however, has high molecular weight and viscosity as well as water-insolubility, These natures may restrict applications in various fields, especially in in vivo system. While the hydrolysates of chitosan, chitooligosaccharides (COS) are not only lower in the molecula. weight and viscosity, but also water-soluble. Thus, they would be expected more efficient absorption in vivo. Besides several documents have been reported antibacterial activities of COS against microorganisms (Kendra et al., 1989; Uchida et al., 1989). (omitted)

• Journal of The Korean Society of Grassland and Forage Science
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• v.20 no.1
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• pp.19-24
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• 2000

This study was camed out in order to establish plant regeneration via seed-derived callus of perennialryegrass.Varietal difference in callus growth and plant regeneration was obvious between two cultivars of perennialryegrass. "Reveille" showed a relatively high capacity for plant regeneration. The MS medium was superiorto SH or Bj in callus formation and plant regeneration. The highest regeneration frequency (60%) from calluswas obtained in presence of 5 mg/ l 2,4-D and 1 mg/ t kinetin. Regeneration response varied among calluscultures initiated from the same cultivar. Regeneration frequency was the most effective in 6 weeks-old calliafter initiation and lost their regeneration capacity gradually over a period of 12 weeks.(Key words : Perennial ryegrass (Lolium perenne L.), Plant regeneration)e L.), Plant regeneration)

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.5
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• pp.62-65
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• 2000

This paper deals with the design and evaluation of the evaluation of the robust controller for a synchronous generator excitation system to improve the steady state and transient stability. The nonlinear characteristics of the system is treated as model uncertainties, and then the robust control techniques are introduced into the power system stability design to take into account these uncertainties at the controller design stage. The performance of the designed controller is examined by extensive non-linear time domain simulation. It is shown that the performance of the robust controller is superior to that of the conventional PI controller.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.6
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• pp.595-606
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• 2000

In order to compare analytical conditions for measuring PAHs(polycyclic aromatic hydrocarbons) in ambient air, a series of experiment were conducted using three different types of extraction methods that include:(1) accelerated solvent extraction (ASE), (2) soxhlet, and (3) sonification methods. Efficiency and relevant analytixal parameters for each of these methods were examined on five different types of solvents that include:(1) 10% diethyl ether in n-hexane(v/v), (2) dichloromethane, (3)cyclohexane.(4) toluene, and (5) Benzene: ethanol (4:1). Comparison of extraction efficiency for various combinations between methods and solvents was made through an application of both internal and external standard calibration techniques. The extraction efficiency tests, when checked using both internal and external standards, allowed us to derive meaningful comparison among different techniques and among solvents.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.173-180
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• 2000

European side impact analysis of an electric vehicle was done using robust design. Locations and section properties of some of the vehicle structure components which influence the european side impact characteristics were chosen as the main factors for the robust design. Eight factors were considered for the analysis: one with two level and seven with three level combinations comprising the L18(21$\times$37) orthogonal array. It is shown that the sensitivities of the factors and the best combination of the factors can be obtained, and that the location of the main components were as much sensitive as the section properties of those. Also it is shown that the interactions were existed between some factors.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.188-195
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• 2000

This study was conducted to develop the mathematical model and the computer simulation program(TPPMWV) for predicting the tractive performance of off-road wheeled vehicles operated on various soil conditions. The model takes into account main design parameters of a wheeled vehicle, including the radius and width of front and rear tires, the weight of vehicle, wheelbase and driving type(4WD, 2WD). Soil characteristics, such as the peressure-sinkage and shearing characteristics and the response to repetitive loading, are also taken into consideration. The effectiveness of the developed model was verified by comparing the predicted drawbar pulls using TPPMWV with measured ones obtained by field tests for two different driving types of wheeled vehicle. As a results, the drawbar pulls predicted by the TPPMWV were well matched to the measured ones within the absolute errors of 5.25%(4WD) AND 9.42%(2WD)for two different driving types, respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.165-172
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• 2000

The VDC(Vehicle Dynamic Control) is a control system whose target is to improve stability of a vehicle under lateral motion. A lateral vehicle motion, especially on a slippery road, can lead to a hazardous situation, and the situation can even worsen by the driver`s inappropriate response. In this paper, two VDC systems, a fuzzy-based controller and an LQR-based controller have been developed. The controllers take as input the yaw rate and the sideslip angle of either body or rear wheel, and they yield the direct yaw moment signal by which the vehicle can gain stability during cornering. Simulations have been conducted to evaluate the performance of the control system. The results indicated that the controllers can successfully improve vehicle stability under potentially dangerous driving conditions.