• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.1807-1812
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• 2014

A plastic has a various advantages in engineering elements that it can be formed a curve surface without restriction of shape and product the high volume with various color and lower price. Also, it is being used for many parts of automobile as the weight of cars is getting lighter. The Door A-Fuel Filler is a automobile plastic part by injection molding production. The injected products are involved a lot of factors for the inferior goods after painting. Therefore the painted products are required to have the process of the polishing in order to eliminate the faults. Now polishing process is being worked by hands. The workers tend to evade the process of polishing because the working needs a lot of powers momentarily. This paper presents the development of auto-polishing system that can check the inferior goods by the vision system and control the polishing process by the motion system. As a result, Shorten production time (30 seconds), and decreases by 1 person to work to increase the competitiveness of the production cost was to expect improvement.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.3
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• pp.130-134
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• 2016

Due to the need for advanced technologies in the automotive industry, the demand for lighter and safer vehicles has increased. Even though various nonferrous metals, like Aluminum, Magnesium and also Carbon Fiber Reinforced Plastic (CFRP), have been implemented in the automotive industry, a lot of technical research and development is still focused on ferrous metals. In particular, the market volume of High Strength Steel (HSS) parts and Ultra High Strength Steel (UHSS) by hot press forming parts has expanded significantly in all countries' automotive industries. A new tool steel, High Thermal-Conductivity Tool Steel (HTCS), for stamping punches and dies has been developed and introduced by Rovalma Company (Spain), and it is able to support better productivity and quality during hot press forming. The HTCS punches and dies could help to reduce cycle time due to their high thermal conductivity, one of the major factors in hot press forming operation. In this study, test dies were manufactured in order to verify the high thermal conductivity of HTCS material compared to SKD6. In addition, thermal deformation was inspected after the heating and cooling process of hot press forming. After heating and cooling, the test dies were measured by a 3D scanner and compared with the original geometry. The results showed that the thermal deformation and distortion were very small even though the cooling time was reduced by 2 seconds.

• Journal of Technologic Dentistry
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• v.34 no.2
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• pp.75-81
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• 2012

Purpose: All ceramic crown, made from zirconia instead of metal for core material, is recognized the best esthetical prosthesis. Recently, high-priced zirconia blocks and expensive CAD/CAM machines come into use for making zirconia core. In this study, slip casting process is adapted to evaluate the possibility of the recycling the remained parts of zirconia block after machining. Methods: Remained zirconia blocks were reduced to powders with zirconia mortar, and screened with 180 mesh sieve. Passed powders were ball milled under various conditions to obtain the optimum zirconia slip for casting. Solid casting method was used for casting the specimens with plaster mold. Formed specimens were dried and biscuit fired at $1,000^{\circ}C$ for 1 hour. Biscuit fired specimens were finished with exact shape of square pillar. Finished specimens were fired from $1,200^{\circ}C$ to $1,550^{\circ}C$ at $50^{\circ}C$ intervals for 1 hour. Linear shrinkage, apparent porosity, water absorption, bulk density, and flexural strength were tested. Microstructures were observed by SEM. Results: Above examinations indicated that the optimum firing temperture was $1,500^{\circ}C$, and when fired at this temperature for 1 hour, apparent porosity was 0% and flexural strength was 680MPa. SEM photomicrographs showed uniform 200~300nm grain size, which is equal with microcture of sintered commercial zirconia block. when compare 24% linear shrinkage of cast specimen with 20% linear shrinkage of CAD/CAM machined block, it was estimated that the size controlling of cast core was not so difficult. Conclusion: According to the all of this experimental results, the cast zirconia core produced from the remained parts of zirconia block was possible to use for all ceramic denture.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.4
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• pp.388-395
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• 2015

The waste gate valve (WGV) for gasoline vehicles operate in a harsh high-temperature environment. Hence, WGVs are typically made of Inconel 713C, which is a type of Ni-based superalloy. Recently, the metal injection molding (MIM) process has attracted considerable attention for parts used under high-temperature conditions. In this study, an MIM analysis for the head and other parts of the WGV is conducted using a commercial CAE program Moldflow. Further, optimal manufacturing conditions are determined by analyzing flow characteristics at various injection times and locations. Moreover, to improve the accuracy of the analysis results, we compare the actual temperature of the mold during injection processing with that observed through the analysis. As the results, metal injection patterns of analysis are well in accord with these of short shot test. And the temperature variations of analysis is also very similar with those of feedstock when metal injection molding.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.69-74
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• 2017

In the current machining industry, machining precision is necessary and machining is being carried out. In this ultra-precision machining industry, the fixation of the workpiece is very important and the degree of machining depends on the degree of fixation of the workpiece. In ultra-precision machining, various methods, such as using a vise chuck or the like and using bolt nut coupling, are used for fixing a workpiece to an existing machine tool. In particular, when the precision gripping force of the jig is insufficient during machining of the ultra-precision mold parts, the machining material shakes due to the vibration or friction, and the machining precision is lowered. In the ultra-precision machining of power transmission parts, such as gears, the accuracy of the product is then determined. In addition, the amount of heat generated during machining has a significant effect on the machining accuracy. This is because the vibration value changes according to the grasp force of the jig that fixes the workpiece, and the change in the calorific value due to the change in the main shaft rotation speed of the ultra-precision machining. The increase in the spindle rotation speed during machining decreased the heat generation during machining, and the machining accuracy was also good, and it was confirmed that the machining heat changed according to the fixed state of the workpiece and the machining accuracy also changed. In this study, we try to optimize the driving part of the power vise by using structural analysis, rather than the power vise, using the basic mechanical-type power unit.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.6
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• pp.426-432
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• 2021

Injection molding is used in many industrial fields such as home appliances, vehicle parts, and electronic device parts because various resins can be molded, leading to mass production of complex shapes. Generally, the empirical prediction method is used to set the initial processing conditions of injection molding. However, this approach requires a lot of cost and its presented solution is not accurate. In this paper, injection molding was simulated through the Moldflow^TM in order to manufacture the spacer for gas insulated switch. Through the simulation, the flow of the resin with respect to the diameter of the inlet was analyzed. It was found that the process was possible at a higher resin temperature as the diameter of the inlet increased. In addition, through thermal analysis during injection of the resin, it was confirmed that a stagnation phenomenon occurred at the insert portion during injection molding, and the temperature of the resin was higher than that of the mold. As in this paper, if the spacer is manufactured by optimizing the injection hole and the temperature of the injection process based on simulation, it is expected that the spacer can be manufactured with high productivity.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.295-299
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• 2022

In this paper, paint-free metallic plastic material, polypropylene (PP) and acrylonitrile styrene acrylate (ASA) materials were investigated on the applications for bumper skid plate and outside mirror housing parts. In order to maximize metallic effect, type, size and content of aluminum pigment were optimized based on flop index. Hybrid aluminum pigments with different aspect ratios were used to conceal weld lines. By controlling the fluidity of the material, the flow mark problem, generated on the surface of the part, was resolved. We also investigated the surface defects of flow and weld lines by using the developed modeling and simulation.

• Journal of Surface Science and Engineering
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• v.56 no.6
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• pp.451-456
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• 2023

Transparent conducting films having a three layered structure of ZnO/Cu/ZnO (ZCZ) were deposited onto the glass substrates by using RF and DC magnetron sputtering at room temperature. The emissivity and opto-electrical properties of the films were investigated with a varying thickness(5, 10, 15 nm) of the Cu interlayer. With increasing the Cu thickness to 15 nm, the films showed a enhanced electrical properties. Although ZnO 30/Cu 15/ZnO 30 nm film shows a lower resistivity of 5.2×10^-5 Ωcm, it's visible transmittance is deteriorated by increased optical absorbtion of the films. In addition, X-ray diffraction patterns indicated that the insertion of Cu interlayer improve the grain size of ZnO films, which is favor for the electrical and optical properties of transparent conducting films. From the observed low emissivity of the films, it is concluded that the ZCZ thin films with optimal thickness of Cu interlayer can be applied effectively for the car's window coating materials.

• Transactions of the Society of Information Storage Systems
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• v.8 no.2
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• pp.72-77
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• 2012

The demand for the laptop computer has been increased day by day and most of users ask quiet computer and devices to work in comfortable environment. One of the devices which generate acoustic noise is an external ODD. Unlike the internal ODD, the external ODD is easy to emit noise because it runs outside of the computer and also it is packed with a thin plastic covers. As the disk rotates, vortex flow is generated inside of the cavity due to various and complicated mold parts of the cover. In addition, there is a gap between the disk tray and the upper/lower cases, through which the air flows as well as the noise leaks. In this study, we have proposed how to reduce the acoustic noise of an external ODD using numerical and experimental analysis. The pressure fluctuations and turbulent kinetic energy distributions are calculated for the developed model. The results show that the sound pressure level is reduced by 2.3dB through simple modifications of ribs of the top cover, which remove or suppress flow instabilities inside of the cavity.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.4
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• pp.700-707
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• 2013

Owing to high oil prices and environmental issues, the automobile industry has conducted considerable research and made large investments to manufacture a high-efficiency automobiles. In the case of automobile wheels in which a lightweight material is used to increase the fuel efficiency a mold is used to increase the production efficiency; however, the use of the molding method for this purpose is very expensive. Therefore an automobile wheel consists of two parts. In this study a two-piece automobile wheel is manufactured by the friction stir welding(FSW) of Al6061-T6 to reduce the manufacturing cost and process complexity. The FSW welding tool geometry and rotational speed, and the feed rate are key factors that significantly affect the weld strength. Therefore tensile tests were conducted on specimens produced using various welding conditions, and the optimal FSW welding conditions were applied to manufacture aluminum wheels. To ensure reliability, prototype aluminum wheels were manufactured and their mechanical reliability and safety were evaluated using a durability test, fatigue durability test, and impact test. Through this study, aluminum wheel production was made possible using the FSW method.