• Design & Manufacturing
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• v.14 no.2
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• pp.62-68
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• 2020

Recently, research on precise parts required in aerospace, ship, and automobile industries has been actively conducted. In this paper, electron beam drilling machining parameters were selected and experiments were conducted to compare processing characteristics analysis according to machining parameters through machining experiments of a vaporization amplification sheet to which STS 304 was applied. Also, as a result of measuring the machining. As the thickness gradually increased, it was confirmed that the electron beam could not reach the vaporization amplification sheet and thus melted on the surface of the material. As a result of the experimental analysis, it was analyzed that the vaporization explosion reaction of the vaporization amplification sheet was not normally performed due to the working distance (WD) according to the material thickness.

• Design & Manufacturing
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• v.15 no.2
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• pp.30-35
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• 2021

The casting method uses a mold to solidify a liquid metal to make a solid metal. Since it uses a liquid metal with the least deformation resistance, it has the characteristic that it can easily manufacture even a complex shape. However, the process of solidifying a liquid metal into a solid metal inevitably involves a volume change and contains internal defects such as shrinkage holes. Therefore, in the design of the casting plan, an excess volume called a pressurization compensates for the volume shrinkage. in the product, and it induces the shrinkage hole defects to occur in parts other than the product1). In this study, casting analysis was performed using casting analysis software (anycasting) in order to optimize the design of the tilting gravity casting method for automobile brackets. In particular, the filling and solidification analysis according to the shape and volume of the pressurized metal was conducted, and applied to the actual product to study the effect of the pressurized metal on the shrinkage defect. Through this study, it is possible to understand the effect of the pressure metal on shrinkage defects in the actual product and propose a design of the pressure metal that improves reliability and productivity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.1
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• pp.69-75
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• 2009

This paper studies the aerodynamic performance that the vent mixer-new conceptual supersonic mixer-showed with its geometric characteristics. The hole is 2 mm with 2 mm's distance from the wall in case 1 and with no distance in case 2. In case 3 die hole is 1 mm. Case 1 and case 2 showed the same total pressure recovery ratio, of which the case 3 was lower than that. While cases 1-3 had the same reattachment length, the shear layer was thicker in cases 1 and 2 than in case 3. Within the recirculation zone, cases 1 and 2 had lower pressure loss and higher velocity gradient difference than case 3-they enhance mixing between air and fuel. Separation bubble which is developed by the inflow into the recirculation zone has a significant effect on the total pressure recovery ratio in the combustor. Also separation bubble influences pressure distributions and recirculation flows in the recirculation zone. Therefore, inflow rate of air into the recirculation zone mainly affects the performance of vent mixer.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.45-50
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• 2011

Hot-Press-Forming (HPF), an advanced sheet metal forming method using stamping at a high temperature of about $900^{\circ}C$ and quenching in an internally cooled die set, is one of the most successful forming process in producing crash-resistant parts such as pillars and bumpers with complex shape, ultrahigh strength, and minimum springback. To optimize conditions of a forming quality in HPF process and secure a safe product without any failures, such as fractures and wrinkling, the simulations based on the coupled thermo-mechanical analysis for a hot-press-formed lower control arm are applied with Taguchi's orthogonal array experiment. Three factor variables - the friction coefficient, blank shape, and hole location for burring - are selected to be optimized. The most effective condition of a forming quality for a hot-press-formed lower control arm is suggested. The simulation results are confirmed with experimental ones.

• Journal of Mechanical Science and Technology
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• v.18 no.9
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• pp.1604-1613
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• 2004

This paper presents an effective and reliable evaluation method for fracture strength and material degradation of the micro-structure of high temperature service steel weldment using advanced small punch (ASP) test developed from conventional small punch (CSP) test. For the purpose of the ASP test, a lower die with a minimized ${\Phi}$1.5 mm diameter loading ball and an optimized deformation guide hole of ${\Phi}$3 mm diameter were designed. The behaviors of fracture energy (E$\_$sp/), ductile-brittle transition temperature (DBTT) and material degradation from the ASP test showed a definite dependency on the micro-structure of weldment. Results obtained from ASP test were compared and reviewed with results from CSP test, Charpy impact test, and hardness test. The utility and reliability of the proposed ASP test were verified by investigating fracture strength, behavior of DBTT, and fracture location of each micro-structure of steel weldment for test specimen in ASP test. It was observed that the fracture toughness in the micro-structure of FL＋CGHAZ and ICHAZ decreased remarkably with increasing aging time. From studies of all micro-structures, it was observed that FGHAZ microstructure has the most excellent fracture toughness, and it showed absence of material degradation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1014-1020
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• 2012

This paper focuses on the development of a supporting S/W tool that can minimize designer's manual operations and errors in metal mold design based on a 3D solid model. The scope in this work includes the offset surface modeling, the computation of the padding force, the generation of material table, the decision of hole position, the estimation of the size of raw material, which are the essential parts of press die and mold design in automotive industry. The proposed system has been developed as a plug-in type using Pro/E API and Visual C++ in order to put the system into the menu functions of Pro/E which is one major 3D CAD systems in the manufacturing industry.

• Transactions of Materials Processing
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• v.14 no.2 s.74
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• pp.160-167
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• 2005

In the present study about extru-bending of angle product, the bending of extruded angle products with the $'\Lambda'$ section and 'ㄱ', section can be obtained using two extrusion billets by the hot metal extru-bending machine with the two punches moving in the different velocity. The bending curvature can be controlled by the different velocity of billets through the two-hole container. This paper describes simulations and experiments of extru-bending process that can make bending during extruding by the difference of stem velocities. And they are applied to two kinds of dies, that is, one of them is conical dies with symmetry $'\Lambda'$ section and the other one is conical dies with asymmetry 'ㄱ' section. The results of the forming simulation by $DEFORM^{TM}-3D$ and results of experiments show that the bending phenomenon at the die exit during extrusion can be obtained with two extrusion billet by the two stems moving in the different velocity. And it was known that it is possible to design the structure of conical cavity of extrusion dies and to control the curvature of product through the simulation and experiment of extru-bending process.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1276-1277
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• 2006

The ever increasing requirements on today's compacts with regard to their geometry and precision call for flexible high-precision and most capable production systems. DORST Technologies has coped with these requirements by developing the new HP series for pressing forces between 1600 kN and 16000 kN and the new HS series for pressing forces between 150 kN and 1200 kN. These fully hydraulic presses featuring upper ram, lower ram, core rod, filler, up to 4 lower tool levels and up to 4 upper tool levels with closed-loop controlled movements. Thanks to latest servo technology and an electronic bus system it is possible to have all movements closed-loop controlled in the desired relation to each other. Thus, today's hydraulic presses provide high stroke rates, low energy consumption and a user-friendly interface. The input of data is carried out via clearly arranged screen masks on a touch-screen. The innovative DORST $IPG^{(R)}$ (Intelligent Program Generator) has been designed to support the set-up staff in preparing and optimizing the toolprogram. The combination of the machine type with the hydraulic unit determines the productivity in consideration of the specific application and the part to be pressed. Thanks to the closed-loop control circuits, DORST hydraulic automatic presses of the latest generation ensure unmatched precision and repeatability - and consequently process reliability - often without necessitating subsequent machining steps.

• Journal of the Semiconductor & Display Technology
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• v.18 no.3
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• pp.100-104
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• 2019

We have investigated the feasibility of fabricating fine stripes using needle coating for potential applications in solution-processed organic light-emitting diodes (OLEDs). To this end, we have employed an aqueous poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) solution that has been widely used as a hole injection layer (HIL) of OLEDs and performed needle coatings by varying the process parameters such as the coating gap and coating speed. As expected, the stripe width is reduced with increasing coating speed. However, the central thickness of the stripe is rather increased as the coating speed increases, which is different from other coating processes such as slot-die and blade coatings. It is due to the fact that the meniscus formed between the needle tip and the substrate varies depending sensitively on the coating speed. It is also found that the stripe width and thickness are reduced with increasing coating gap. To demonstrate its applicability to OLEDs, we have fabricated a red OLED stripe and obtained light emission with the width of about 90㎛.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1453-1458
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• 2009

This study is to apply the mechanical press joining method to join two kinds of sheet metals with circular holes by mechanical pressing instead of laser beam. Usage of the mechanical pressing avoids the thermal deformation of sheet metals which occurs inevitably in laser joining. A die design has been proposed to make the mechanical press joining applicable with finite element analysis. Five design factors related to the joining force have been selected and applied to the Taguchi method for optimization. Among five factors, 'Forming Depth' and 'Punch Corner Radius' have been revealed to be the most influential ones.