• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.10a
• /
• pp.449-452
• /
• 2009

This paper was designed to fabricate the miniature spur gear with pitch circle of 1.8 by hot extrusion process of mechanically alloyed Zn-22wt%Al powder at various temperature. The mechanical alloying was preformed for ball milled times of 8h, 16h and 32h by the planetary ball milling. Mechanically alloyed powders were compacted cylindrical performs. Extrusions of the miniature spur gear using the alloyed powder were carried out at different extrusion temperatures. The extruded spur gear was sintered for 2h at $350^{\circ}C$ in argon atmosphere. The friction between the die and the powdered billet and the internally different density due to complex product shape cause the internal crack. To overcome the mentioned problems, high dimensional accuracy at cross section of the spur gear and uniform Vickers hardness could be obtained by graphite lubricant and controlling holding time.

• Proceedings of the KIEE Conference
• /
• 1995.07c
• /
• pp.1356-1358
• /
• 1995

About 20 years have passed since cross-linked polyethylene(XLPE) came into practical use for power transmission cables. In 1969, We were the first to product 33kV XLPE insulated cables, and in 1984 produced XLPE cable for 154kV. To meet the increasing demand for electric power in large cities, and to improve reliability of the power supply, plans are being made to introduce ultrahigh-tension power cable for long distance underground lines in urban areas. Studies are currently under way to develop more than 154kV XLPE cables to meet increasing demand. In this paper presents the progress in the production and design of XLPE cables, and describes ways in which further improvements seems likely.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.8
• /
• pp.840-844
• /
• 2012

Roll forming process is a sheet metal forming process where the forming occurs with rolls in several steps, often from an undeformed sheet to a product ready to use. And each pair of forming rolls installed in a forming machine operates a particular role in making up the required final cross-section. This process used to many industry manufactures and recently apply to automotive industry. This study, FEM simulation applied bumper reinforcement using SHAPE-RF software and analyzed about total effective strain, longitudinal strain, thickness according to the roll-pass.

• Smart Media Journal
• /
• v.2 no.2
• /
• pp.20-27
• /
• 2013

The concept of social media is top of the agenda for many business executives and decision makers, as well as consultants try to identify ways where companies can make profitable use of applications such as Netflix, Flixster. The social media is playing an increasingly important role as the information sources for customers making product choices etc. With the flourish of Web 2.0 technology, customer reviews are becoming more and more useful and important information resources for people to save their time and energy on purchasing products that they want. This paper proposes the Bayesian Probabilistic Classification algorithm to mine the social media review, and evaluates it by different splits and cross validation mechanism from the real data set. The explored study experimental results show the robustness and effectiveness of proposed approach for mining the social media review.

• 한국경영정보학회:학술대회논문집
• /
• 2008.06a
• /
• pp.52-63
• /
• 2008

Virtuality is a product of the information age, and as it plays a larger role in the activities of individuals, groups and organizations, the issue of how human behavior varies between virtual and physical space has become one of the most important questions facing the management environment of today. The purpose of this article is to examine how virtuality shapes individuals' social relationships within and outside their work groups. We developed a conceptual framework that explores the links between virtuality and social network based on computer-mediated communication theory and social network theory. Using data from 172 individuals of 42 project teams in 5 global business consulting firms, we tested cross-level hypotheses. The results of hierarchical linear modeling (HLM) indicate that virtuality significantly influences individual's internal tie strength as well as external bridging ties. The results also show the effects of virtual process via CMC vary along with the virtual context.

• Natural Product Sciences
• /
• v.1 no.1
• /
• pp.66-69
• /
• 1995

Traditional Antheraea pernyi silkworm cocoon is tawny color. The white Antheraea pernyi silkworm cocoons studied here by IR and UV are new breeds of recent breeding. We discovered that the main body of the first grade structure of silk protein in the new white is as same as the one in the traditional tawny Antheraea pernyi silkworm cocoon, yet there are small quantities of cross-linked polymer of gentisic acid and silk protein in the white silkworm cocoons. In spite of the least surviving quantity of the polymer, the white silkworm cocoons are most white and its white color is similar to white Bombyx mori silkworm cocoon.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.05a
• /
• pp.148-151
• /
• 2003

The purpose of this study is to investigate the manufacturing technique on the U type Draw-Bending of inner groove tube. The U type tube requires the quality of product that satisfy sufficient conditions for a heat exchanger. The mandrel components act the important roles that prevent wrinkles and keep the shape of cross section of bended tube at bending process. We performed the FEM simulation using LS-DYNA software and the bending test of inner groove tube and then, compared bending simulation with bending test results about mandrel ball diameter, mandrel position and optimal clearance between mandrel and tube.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.11
• /
• pp.1912-1920
• /
• 1997

In the analysis of metal forming process, ALE(Arbitrary Lagrangian Eulerian) finite element methods have been increasingly used for the capability to control mesh independently from material flow. The methods can be divided into two groups i.e., coupled and split formulations. In the present work, the split ALE formulation is used for computational efficiency. A split ALE finite element method developed for rigid-viscoplastic materials and applied to the analysis of hot square die extrusion. Since thermal state greatly affects the product quality, an ALE scheme for temperature analysis is also presented. As computational examples, profile shapes as square and cross-like sections are chosen.

• International Journal of Precision Engineering and Manufacturing
• /
• v.1 no.1
• /
• pp.146-151
• /
• 2000

The importance of shape reconstruction is increasing in many areas such as RPD(Rapid Product Development) and reverse engineering. Typical data in these areas are mainly classified as the shape data measured by a laser scanner and the data extracted from the CT image. The goal of this research is to realize three-dimensional shape construction by showing a possible way to analyze input image data and reconstruct the original shape. Two main steps of the reconstructing process are obtaining cross-section data from image processing and linking loops between one slice and the next. Objects reconstructed in this way are compared with other objects using a laser scanner and modelled by commercially available software. The technique is expected to be used in reverse engineering applications and the object modeling with automated process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.05a
• /
• pp.85-88
• /
• 2001

Examination of the die design is carried out for a multi-stage rectangular cup drawing process with the large aspect ratio with the aid of the finite element analysis. The analysis considers the deep drawing process with the ironing process for the thickness control in the cup wall. Simulation is performed to investigate the deformation mechanism in the initial design and the modified design. The analysis clarifies that the irregular cross section and the irregular contact condition produces unfavorable deformation. The analysis results show that the modified design improves the quality of a deep-drawn product with the low possibility of failure. The analysis result also shows good agreement with the experimental one.