• Proceedings of the KIEE Conference
• /
• 2004.07c
• /
• pp.2083-2086
• /
• 2004

Variable Structure Controller with effective tracking performance is propose to control micro actuator system. Propsed VSC(Variable Structure Control) technique is implemented to tracking control of comb driving system having high non-linearity. The tracking performance due to VSC technique is compared to conventional PD(Proportional Derivative) control technique, reveals improved results.

• Korean Journal of Pharmacognosy
• /
• v.14 no.2
• /
• pp.39-43
• /
• 1983

Polyamine constituents of fresh Panax ginseng root and dried white ginseng were extracted with 5% trichloroacetic acid, respectively. The isolation of polyamine constituents was conducted by the cation exchange chromatography using $Dowex-50W{\times}8$ resin and the detection was performed with TLC. Identification of the polyamine was carried out by the methods of IR, NMR, MS spectroscopy and GLC. Polyamine constituents of white and fresh ginseng root were identical and composed of five different polyamines. The major polyamine in white and fresh ginseng root was determined as putrescine.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.10a
• /
• pp.271-274
• /
• 2009

This paper deals with an evaluation of the product quality according to intermesh of the roller straightening process of a steel cord. To perform the experiments, a single-layered steel cord with three wires is selected as a target. Intermeshes at inlet and outlet of the roller straightening device are selected as a respective design parameter. According to two intermeshes of the roller straightening device, a design table is generated and experiments were performed. Three assessment items of the product quality, such as the residual torsion, the arc-height and the pre-forming ratio, are measured in each experimental case for the quantitative evaluation of a steel cord. Based on the measured data, the sensitivity of two intermeshes was analyzed and the prediction equation for the product quality of a steel cord was also constructed from the regression analysis.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.10a
• /
• pp.81-84
• /
• 2001

An inverse finite element approach is employed for more capability to design the optimum blank shape from the desired final shape with small amount of computation time and effort. In some drawing or stamping simulation with inverse method, it is difficult to apply inverse scheme due to the large aspect ratio or steep vertical angle of inclination. The reason is that initial guesses are hard to make out with present method for those cases. In this paper, a direct mesh marring scheme to generate initial guess on the sliding constraint surface described by finite element patches is suggested for one step inverse analysis to calculate initial blank shape. Radial type mapping is adopted for the simulation of rectangular cup drawing process with large aspect ratio and parallel type mapping for the simulation of S-Rail forming process with steep vertical angle of inclination.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.10a
• /
• pp.93-96
• /
• 2001

Design sensitivity is calculated in the sheet metal forming process with an elasto-plastic finite element analysis and a direct differentiation method The sensitivity analysis is concerned with the time integration the constitutive relation considering planar anisotropy, shell elements and the contact scheme. The present result is compared with the result obtained with the finite difference approach in deep drawing processes. The obtained sensitivity information is applied to the simple optimization process for the sheet metal forming process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.10a
• /
• pp.106-109
• /
• 2001

Process parameters of roller levelling process are intermesh of each roller, roller angle, roller arrangement and shape of rollers. Experimental optimization of these process parameters is very troublesome because of difficulties in evaluating the straightness of pipes to be levelled quantitatively. Finite element method can be a very efficient way to evaluate the straightness of the pipes and therefore to optimize the process. This paper is concerned with simulation and optimization of a roller levelling process. Process parameters of a 14-roller levller for aluminum T9 pipes are optimized with finite element method and Taguchi method. Parameters of significance in roller levelling process and their optimum are obtained.

• Transactions of Materials Processing
• /
• v.11 no.2
• /
• pp.147-154
• /
• 2002

The tension levelling Process is Performed to elongate the strip plastically In combination of tensile and bending strain so that all longitudinal fibers In the strip have an approximately equal amount ofn length and undesirable strip shapes are corrected to the flat shape. Thus paper is concerned with a simulation of the tension levelling process based on the analysis of tile unit model for the tension leveller. Analysis technique such as the sequential analysis of the unit model is suggested and verified with the assembly analysis of the unit model for the effective arts economic analysis of the full set of the tension leveller. Analysis of the full tension levelling Process using sequential unit models Is carried out for steel strips with the shape defect and provides the effect of the intermesh and optimum amount of the intermesh in tension levelling process.

• Transactions of Materials Processing
• /
• v.8 no.4
• /
• pp.347-355
• /
• 1999

The paper is concerned with an improved scheme for application of the blank holding force in order to take account of the thickness distribution in the sheet material of the flange region. The scheme incorporates with a modified membrane finite element method for planar anisotropic materials. The new scheme proposed two coefficients α and βto calculate the compressive stress in the sheet metal due to the blank holding force, which should be determined properly for accurate analysis. The effect of αand βon the blank holding force distribution and the deformed shape is investigated with simulation of rectangular cup deep drawing processes by changing parameter values.

• YAKHAK HOEJI
• /
• v.38 no.1
• /
• pp.20-23
• /
• 1994

The contents of ginkgolides were determined in the leaves of male and female Ginkgo biloba from late spring until mid-autumn. Ginkgolides were detected during the whole growing season in the leaves of each tree. Ginkgolides content was low in late spring, gradually increased to reach a maximum in august and decreased thereafter. The male trees have two or three times higher ginkgolides content than the female trees. Comparing our results with that of previously reported values, the sexual variation of ginkgolides content seemed not to be genetic.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.6
• /
• pp.1810-1818
• /
• 1996

A new finite elemetn approach is introduced for direct prediction of bland shapes and strain distributions from desired final shapes in sheet metal forming. The approach deals with the geometric compatibility of finite elements, plastic deformation theory, minimization of plastic work with constraints, and a proper initial guess. The algorithm developed is applied to cylindrical cup drawing, square cup drawing, and fron fender forming to confirm its validity by demonstratin reasonable accurate numerical results of each problems. Rapid calculation with this algorithm enables easy determination of various process variables for design of sheet metal forming process.