• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.549-556
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• 2010

In general, materials that can be used to form elastic pads, such as urethane and rubber, are often used in flexible forming processes by inserting the pads between a blank and flexible die for smoothing the forming surface that is formed by a reconfigurable die. In this study, the effects of the elastic pad on formability in the flexible forming process for sheet metals are investigated by performing numerical simulations. In the simulation, the hyperelastic material model is used, where the urethane elastic pads serve as elastic cushions. Case studies are carried out for elastic materials with different hardness values and thicknesses. The results are used to evaluate formability by comparing the configuration of the deformed blank and its major cross-sectional profiles. It is verified that the elastic pad used in the flexible forming process for sheet materials should be hard and that its thickness should be chosen appropriately.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.24.1-24.1
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• 2011

CMP (Chemical Mechanical Planarization)는 고직접도의 다층구조의 소자를 형성하기 위한 표면연마 공정으로 사용되며, pattern 크기의 감소에 따른 공정 중요도는 증가하고 있다. 반도체 소자 제조 공정에서는 낮은 비용으로 초기재료를 만들 수 있고 우수한 성능의 전기 절연성질을 가지는 산화막을 만들 수 있는 단결정 실리콘 웨이퍼가 주 재료로 사용되고 있으며, 반도체 공정에서 실리콘 웨이퍼 표면의 거칠기는 후속공정에 매우 큰 영향을 미치므로 CMP 공정을 이용한 평탄화 공정이 필수적이다. 다결정 실리콘 박막은 현재 IC, RCAT (Recess Channel Array Transistor), 3차원 FinFET 제조 공정에서 사용되며 CMP공정을 이용한 표면 거칠기의 최소화에 대한 연구의 필요성이 요구되고 있다. 본 연구에서는 알칼리성 슬러리를 이용한 단결정 및 다결정 실리콘의 식각 및 연마거동에 대한 특성평가를 실시하였다. 화학적 기계적 연마공정에서 슬러리의 pH는 슬러리의 분산성, removal rate 등 결과에 큰 영향을 미치고 연마대상에 따라 pH의 최적조건이 달라지게 된다. 따라서 단결정 및 다결정 실리콘 연마공정의 최적 조건을 확립하기 위해 static etch rate, dynamic etch rate을 측정하였으며 연마공정상의 friction force 및 pad의 온도변화를 관찰한 후 removal rate을 계산하였다. 실험 결과, 단결정 실리콘은 다결정 실리콘보다 static/dynamic etch rate과 removal rate이 높은 것으로 나타났으며 슬러리의 pH에 따른 removal rate의 증가율은 다결정 실리콘이 더 높은 것으로 관찰되었다. 또한 다결정 실리콘 연마공정에서는 friction force 및 pad의 온도가 단결정 실리콘 연마공정에 비해 상대적으로 더 높은 것으로 나타났다. 결과적으로 단결정 실리콘의 연마 공정에서는 화학적 기계적인 거동이 복합적으로 작용하지만 다결정 실리콘의 경우 슬러리를 통한 화학적인 영향보다는 공정변수에 따른 기계적인 영향이 재료 연마율에 큰 영향을 미치는 것으로 확인되었으며, 이를 통한 최적화된 공정개발이 가능할 것으로 예상된다.

• Elastomers and Composites
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• v.43 no.3
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• pp.173-182
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• 2008

Rubber-pad forming process for materials such as metal in which portions of the die which act upon the material is composed of a natural or synthetic rubber or elastomer material. This makes the rubber pad forming process relatively cheap and flexible, high accuracy for small product series in particular. In this study, we carried out the physical test and finite element analysis of elastomer such as natural rubber and urethane for steel rack rube forming. The non-linear property of elastomer which are described as strain energy function are important parameter to design and evaluate of elastomer component. These are determined by material tests which are uni-axial tension and bi-axial tension. This study is concerned with simulation and investigation of the significant parameters associated with this process.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.3
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• pp.37-44
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• 2000

The corrosion behavior of aluminum pad coated with epoxy molding compound (EMC) was investigated using electrochemical impedance spectroscopy (EIS). The impedance change was evaluated by the absorption of deionized water (DI water) to EMC coating and the interface between EMC and aluminum. During the absorption a decrease in resistance and thus an increase in capacitance of EMC as well as the interface of EMC/Al could be observed. Up to about 170 hours of absorption the EMC was saturated with the water molecules and ions generated from EMC. Subsequently the ionic water was penetrated to the interface and finally the corrosion of aluminum was occurred by the Dl water and ions. From measuring the adhesion strength with the Dl water absorption it was expected that the saturation of water and ions in the interface decreased the adhesion strength. The higher filler content of EMC should be necessary to inhibit the corrosion of aluminum electrode in microelectronic packages.

• Korean Journal of Materials Research
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• v.25 no.1
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• pp.21-26
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• 2015

CMP(Chemical Mechanical Polishing) Processes have been used to improve the planarization of the wafers in the semiconductor manufacturing industry. Polishing performance of CMP Process is determined by the chemical reaction of the liquid sol containing abrasive, pressure of the head portion and rotational speed of the polishing pad. However, frictional heat generated during the CMP process causes agglomeration of the particles and the liquidity degradation, resulting in a non-uniform of surface roughness and surface scratch. To overcome this chronic problem, herein, we introduced NaCl salt as an additive into silica sol for elimination the generation of frictional heat. The added NaCl reduced the zata potential of silica sol and increased the contact surface of silica particles onto the sapphire wafer, resulting in increase of the removal rate up to 17 %. Additionally, it seems that the silica particles adsorbed on the polishing pad decreased the contact area between the sapphire water and polishing pad, which suppressed the generation of frictional heat.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.5
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• pp.52-62
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• 2022

A launch vehicle is a one of the biggest hardware among the products of human technology. For huge size launch vehicles, to transport to Launch Complex and to erect on launch pad precisely and safely is very critical issue. Therefore, a final assembly, transportation, erection and holding in vertical position in launch pad requires very precise operational technology, processes and related aggregates. Those operational concept has been developed to comply with the requirement of each launch vehicle and technology level at that time. In this paper, a progress of operational methodology in global launch vehicles are described. In addition, methodologies used on the KSLV-1 Naro and the KSLV-II Nuri launch vehicle are introduced.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.3
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• pp.389-396
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• 2013

Epidermal hydration is mainly maintained by natural moisturizing factors (NMFs). Of these various NMFs, free amino acids (AAs) are major constituents generated by filaggrin degradation. The reduction of these AAs has been reported in aging skin induced during menopause. In this study, we examined whether the dietary supplementation of royal jelly (RJ) during the pre- and post-menopausal period alters epidermal levels of filaggrins, free AAs, and peptidylarginine deiminase-3 (PAD-3) (an enzyme involved in filaggrin degradation processes). Sprague Dawley rats were divided into five groups: groups fed a control diet for 12 weeks, in which an ovariectomy (OVX) or sham operation (SHAM) were underwent at week 4; groups fed a diet with 1% RJ harvested in different area of Korea (RJ1 and RJ2); and a group fed a diet with isoflavone (IF), the typical functional food for menopause prevention, for 4 weeks before and 8 weeks after an ovariectomy operation. In the epidermis of group OVX, total filaggrins (including profilaggrin and filaggrin) were reduced; these levels in groups RJ1 and IF were similar or less than in group OVX. However, total AAs, which showed no apparent difference between groups SHAM and OVX, were highly increased in groups RJ1 and IF. Specifically, aspartate (Asp) and proline (Pro), the major AAs in functioning NMF, were highly increased in group RJ1. Although total filaggrins, profilaggrin, filaggrin and PAD3 increased, total AAs (including Asp and Pro) in group RJ2 were modest or less than in group RJ1. The PAD3 alteration was not apparent among the four other groups. Taken together, we demonstrate that the diet supplementation of RJ1 enhanced filaggrin degradation (but not through the increased protein expression of PAD3), and increased total AAs, Asp and Pro. RJ1 could be a dietary supplementation for preventing the skin aging induced during menopause.

• Information and Communications Magazine
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• v.29 no.9
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• pp.3-9
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• 2012

본고에서는 WWCD2012에서 발표한 iOS 6.0에서는 Maps/Siri/Facetime/Passbook 등의 자체 서비스 강화, Major Service의 Embedded를 통한 Application 기능 강화 등에 초점을 맞추어 개선점을 찾아가고 있다. 이에 대해 Google도 Siri에 대응되는 Google Now를 발표하고, iPad에 대응되는 넥서스7를 발표하였다. 지금까지는 자체 개선점에 주력하며 기능을 하나씩 개선하는데 주력한 것에 비해서 2012년에는 안정적이고 빠른 UI 및 Frameworks의 개선을 제시하면서 사실상 유사한 품질을 제공하려 노력하고 있으며, 경쟁 OS 대비 경쟁을 의식한 기능과 서비스를 계속 제안할 것이다.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.1
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• pp.39-43
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• 2003

Thermal management is very important for the success of high density circuit design in LTCC. In this paper, LTCC substrates containing thermal via and pad were fabricated in order to study the influence of the thermal dissipation. To realize the accurate thermal analysis for structure design, a series of simple thermal conductivity measurement by laser flash method and parametric numerical analysis have been carried out. The LTCC substrate including via and Ag pad has good thermal conductivity over 103 W/mK which is 44% value of pure Ag material. Thermal behaviors with via arrays, size and density in the LTCC substrate were studied by numerical method.

• Journal of the Korean Vacuum Society
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• v.10 no.3
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• pp.361-367
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• 2001

Recently, Chemical Mechanical Polishing(CMP) has become a leading planarization technique as a method for silicon wafer planarization that can meet the more stringent lithographic requirement of planarity for the future submicron device manufacturing. The SOI(Silicon On Insulator) wafer has received considerable attention as bulk-alternative wafer to improve the performance of semiconductor devices. In this paper, the objective of study is to investigate Material Removal Rate(MRR) and surface micro-roughness effects of slurry and pad in the CMP process. When particle size of slurry is increased, Material Removal rate increase. Surface micro-roughness is greater influenced by pad than by particle size of slurry. As a result of AM measurement, surface micro-roughness was improved from 27 $\AA$ Rms to 0.64 $\AA$Rms.