• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.10
• /
• pp.1475-1482
• /
• 2004

In this paper, the rigid-viscoplastic finite element solutions obtained by MINI-elements based triangular elements and tetrahedral elements are compared with those obtained from numerically well-behaved rectangular and hexahedral elements. The theoretical background of the MINI-elements is introduced in detail and the rigid-viscoplastic finite element formulation is also given. Discussion on the results of the MINI-elements is made with emphasis on the effect of a stabilizer simplifying velocity-bubble coupled terms.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.4
• /
• pp.762-767
• /
• 2010

This paper describes characteristic of a light triggered thyristor investigated by experiment to adopt it into a main switch of a pulsed power unit. Triggering principle of the light triggered thyristor are referred with its structure and equivalent circuit. Operational principle and simulation result of a capacitive pulsed power circuit are explained. A variety of triggering conditions of triggering circuit and characteristics on turn-on, turn-off, voltage dividing in series operation, overvoltage protection function of the light triggered thyristor are investigated by experiments. Experimental result of 40 kJ pulsed power unit using the light triggered thyristor is presented.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.9 no.5
• /
• pp.80-86
• /
• 2000

The Tailor Welded Blanks(TWB) are using various materials (different thickness, strength and different materials) can be welded together prior to the forming process. Therefore, TWB applications have become little by little important in automobile industries, because it has more light weight and process reduction. A burnish area is very important for TWB using laser welding. In this paper, evaluated failure criterion, effect of clearance and distance of between pad and punch by computer simulation. We used element separation method for fracture. And applied a plastic strain to failure criterion. According to the analysis results, we obtain failure criterion, when plastic strain is 2.0. The burnish area and clearance were inverse proportional.

• Proceedings of the Korean Society for Bioinformatics Conference
• /
• 2005.09a
• /
• pp.300-304
• /
• 2005

Molecular dynamics of nanosecond timescale could provide a significant result for the structure analysis of oligopeptides. The most surprising was the fact that Chou-Fasman parameters which have no direct relationship with nanosecond molecular dynamics could implicate the result to a certain extent. A novel parameter termed X %-stickiness, which is another measure of compactness of a molecule, was first introduced effectively.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1686-1690
• /
• 2005

Although metal ball can be used as parts of bearing or metal filter, that is used by single product with solder ball or shot ball. Also, according as demand of metal ball of various diameter increase, processing property 솜 extension of coverage are important. Especially an optimal design of cutting roller was investigated for determining appropriate dimensions of components of manufacturing system. In this study, the effects of the diameter and the round radius of cutting roller were calculated and analyzed. We applied data of rigid-plastic FEM Simulation in basis design of equipment to solve these issues, and confirmed processing factor about metal ball manufacturing process that use cutting process of metal wire in this research

• Journal of the Korean Statistical Society
• /
• v.26 no.1
• /
• pp.131-146
• /
• 1997

In this paper the problem of measuring the stochastic dependence among sets fo random variates is considered, and attention is specifically directed to forming a single well-defined measure of the dependence among sets of normal variates. A new information theoretic measure of the dependence called dependence index (DI) is introduced and its several properties are studied. The development of DI is based on the generalization and normalization of the mutual information introduced by Kullback(1968). For data analysis, minimum cross entropy estimator of DI is suggested, and its asymptotic distribution is obtained for testing the existence of the dependence. Monte Carlo simulations demonstrate the performance of the estimator, and show that is is useful not only for evaluation of the dependence, but also for independent model testing.

• Communications for Statistical Applications and Methods
• /
• v.18 no.3
• /
• pp.301-317
• /
• 2011

Statistical and probabilistic behaviors of fibers forming fiber webs of all kinds are of great significance in the determination of the uniformity and physical properties of the webs commonly found in many industrial products such as filters, membranes and non-woven fabrics. However, in studying the spatial geometry of the webs the observations must be theoretically as well as experimentally confined within a specified unit area. This paper provides a general theory and framework for computer simulation for quantifying the fiber segments bounded by the unit area in consideration of the "edge effects" resulting from the truncated length segments within the boundary. The probability density function and the first and second moments of the length segments found within the counting region were derived by properly defining the seeding region and counting region.

• Transactions of Materials Processing
• /
• v.11 no.4
• /
• pp.302-311
• /
• 2002

A generalized numerical approach based on the finite element method to analysis and design of hydroforming process is proposed in this paper. The special attention is focused on comparison of an implicit and an explicit finite element method widely used for hydroforming simulation. Furthermore, in order to meet the increasing real needs for prediction of forming limit, a ductile fracture criterion combined with finite element method is introduced and then applied to hydroforming process of an automobile lower m Consequently, the numerical analysis and design for hydroforming process presented here will facilitate the development and application of the tube hydrofoniung process to a new level.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.05a
• /
• pp.88-91
• /
• 2003

The forging of Al 6061 has been studied by using finite element analysis and real forging experiment to find out the effect of strain rate and strain on the final forged product. It seems to be well known that the mechanical properties depend on the microstructures of forged products. The hot deformation of Al alleys including Al 6061 has been researched quite a long period on the various aspects. However, the forging of Al alloys seem to have few information, especially the recrystallization, recovery and grain growth. To elucidate the process variables to control those microstuctual aspects the specially designed model was used for finite element simulation and forging experiments, in which the variation of strain and strain rate could be obtained. The effect of strain md strain rate has been related with the microstructures of forging stocks.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.6
• /
• pp.127-134
• /
• 2000

The current three-stage cold farming process to produce a flange is investigated for the purpose of improvement of manufacturing process. The main goal of this study is to obtain an appropriate process sequence, which can produce the required part with less manufacturing cost. The current process sequence is simulated using finite element method and design criteria are examined. Based on the results of simulation of the current three-stage process. a design strategy for improving the process sequence is analyzed using the thick-walled pipes. Because it has a reduced process-sequence without buckling of the workpiece or overloading of tools, the new process has distinct advantages over the conventional process. Numerical results show that the newly proposed process with selected presses is the most economical way to produce the required part.