• Journal of Korea Foundry Society
• /
• v.14 no.6
• /
• pp.576-589
• /
• 1994

Water modeling experiments and computer simulation for the predictions of defects of die castings are very important to produce high quality castings with less cost. The relation between the variable air vent system and the characteristics of the fluid flow in the die cavity is studied by using water modeling tests, which give ideas on reasonable designing of die cavity, vent arrangement and gating system. In order to test the water modeling, injection is done by using water containing NaCl. Flow behaviors in cavities are visualized by high speed camera and video tape recorder, and local filling time is measured with electrode sensors. Special attention is paid to the configuration of die cavity. Simulated results by computer are examined and compared with the results of water modeling experiments. There are close correlations between the simulated results and water modeling ones.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.10a
• /
• pp.66-68
• /
• 2009

Most hard disk spindles currently used are supported by oil lubricated hydrodynamic bearings. However, in the trend of increasing spindle speed and reducing size and cost, dynamic behaviors of the bearing such as RRO and NRRO are more important. A novel system evaluating dynamic behavior of hydrodynamic bearings in had disk drive was developed to analyze the effect of groove shapes and parameters.

• Journal of Game and Entertainment
• /
• v.1 no.1
• /
• pp.1-7
• /
• 2005

Beta-test is a essential step to verify a online-game developing. Through beta-test, we can find out some problems related to game-balancing, game-play, user behaviors and so on. And the game developing can be modified to make up a weak-point. However, a beta-test in online game development is a very time consuming and heavy expense work. Therefore, in this study, the simulation model for growth-balancing and battle among characters was proposed in order to reduce the duration and cost for beta-test. And it was applied to Travia online game successfully.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.10
• /
• pp.1720-1724
• /
• 2007

Electrochemical behaviors of bovine hemoglobin (Hb) at an acetylene black paste electrode based on the enhancement effect of sodium dodecyl sulfate (SDS) were investigated. In the optimal conditions, a very weak reduction peak was observed at an acetylene black paste electrode for hemoglobin in the absence of SDS. However, the reduction peak current increased remarkably after the addition of 4.0 × 10?4 mol L?1 SDS, suggesting that SDS exhibits obvious enhancement effect to the determination of hemoglobin. All the experimental parameters, such as pH value, concentration of SDS, accumulation time and accumulation potential were optimized for hemoglobin analysis. The proposed method possesses high sensitivity (detection limit is 3.0 × 10?9 mol L?1), wide linearity (6.0 × 10?9 to 6.0 × 10?7 mol L?1), rapid response and low cost. Finally, the method was successfully employed to determine hemoglobin in a spiked sample.

• 한국경영정보학회:학술대회논문집
• /
• 2007.06a
• /
• pp.339-344
• /
• 2007

In the cut-throat competitive environment of business, large-scale IS investment is becoming inevitable strategic necessity for gaining competitive advantage. However. it bears great deal of risk over all the associated processes so that the investment decisions need to be taken in a greatly careful manner. Nonetheless, Korean organizations are prominently showing risk taking behaviors regarding major is investment, in terms of system downsizing. Although decision theory argues decision makers' rational choice of options through the assessment of risk and benefit, the notable trend toward system downsizing in Korea defies common understandings on IS project risk. Furthermore, it encourages us to investigate many impenetrable characteristics underlying organizational risk taking decisions with IS investment. We found out that there is Significant effect of IS decision makers' risk propensity when they make system downsizing decisions. Moreover. we Identified that IS decision makers do not get a strong pressure of cost savings and have tendencies to mimic competitor's decisions.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.4
• /
• pp.287-295
• /
• 2014

Smart manufacturing (SM) considered as a new trend of modern manufacturing helps to meet objectives associated with the productivity, quality, cost and competiveness. It is characterized by decentralized, distributed, networked compositions of autonomous systems. The model of SM is inherited from the organization of the living systems in biology and nature such as ant colony, school of fish, bee's foraging behaviors, and so on. In which, the resources of the manufacturing system are considered as biological organisms, which are autonomous entities so that the manufacturing system has the advanced characteristics inspired from biology such as self-adaptation, self-diagnosis, and self-healing. To prove this concept, a cloud machining system is considered as research object in which internet of things and cloud computing are used to integrate, organize and allocate the machining resources. Artificial life tools are used for cooperation among autonomous elements in the cloud machining system.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.12
• /
• pp.111-118
• /
• 2007

Hydroforming is a cost-effective way of shaping malleable metals such as steel into lightweight, structurally stiff and strong pieces. With the increased use of the hydroformed components in automotive and aerospace industries, it is important to know the variations of the mechanical properties in the hydroforming process far the safe and durable design purposes. The principal goal of this paper is to suggest a procedure to evaluate the variations of tensile and fatigue properties before and after a hydroforming process. A miniature specimen, which is 0.2 mm thick and 2.3 mm wide, is devised and tested to measure local mechanical properties. The effects of specimen size, defects, surface roughness, and hydroforming on the tensile and fatigue behaviors are discussed.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.9
• /
• pp.116-125
• /
• 2008

Inkjet printing technology with a drop-on-demand (DOD) inkget head technology has been recognized as one of versatile and low cost manufacturing tools in the electronics industry. Concerned with control of driving signal, however, general strategy to optimize jetting stability has not been understood well, because of the inherent complex multi-physics nature in inkjet phenomena. Motivated by this, present study investigates the effect of driving waveforms of piezoelectric head on jetting characteristics of DOD inkjet system focused on jetting stability with phase matching of pressure waves in the print head. The results show that velocities and volumes of the ink jetted droplets were linear relations with the driving signal's maximum voltage, while periodic behaviors are observed with the driving signal's pulse widths.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.14 no.3
• /
• pp.47-53
• /
• 2005

The non-linear finite element program of the large deformation analysis by computer simulation has been used in the prediction and evaluation of the behaviors of the non-linear rubber components. The analysis of rubber components requires the tools modelling the special materials that are quite different from those used for the metallic parts. The nonlinear simulation analysis used in this study is expected to be widely applied in the design analysis and the development of several rubber components which are used In the manufacturing process of many industries. By utilizing this method, the time and cost can also be saved in developing the new rubber product. The objective of this study is to analyze the rubber component with the large deformation and non-linear properties.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.1444-1449
• /
• 2007

Inkjet printing technology with a drop-on-demand (DOD) inkjet head technology has been recognized as one of versatile and low cost manufacturing tools in the electronics industry. Concerned with control of driving signal, however, general strategy to optimize jetting stability has not been understood well, because of the inherent complex multi-physics nature in inkjet phenomena. Motivated by this, present study investigates the effect of driving waveforms of piezoelectric head on jetting characteristics of DOD inkjet system focused on jetting stability with phase matching of pressure waves in the print head. The results show that velocities and volumes of the ink jetted droplets were linear relations with the driving signal's maximum voltage, while periodic behaviors are observed with the driving signal's pulse widths.