• 대한치과보철학회지
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• 제41권4호
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• pp.405-420
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• 2003

Purpose : The purpose of this study was to compare the fracture resistance of the IPS Empress ceramic crown with 1.0mm width rounded shoulder, which is usually recommended in all ceramic crown. and 0.5mm width chamfer finish lines on the maxillary central incisor. Material and method : After 15 metal dies were made for each group, the IPS Empress all ceramic crowns were fabricated and cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. LTD., Japan) on the metal die. The cemented crowns were mounted on the positioning jig and the universal testing machine(Zwick Z020, Zwick Co. Germany)was used to measure the fracture strength with loading on the incisal edge. And also, three-dimensional finite element stress analysis was used to measure the stress distribution with the various types of the finish lines(1.0mm width rounded shoulder, 0.5mm width chamfer), the loading site(incisal edge, incisal $\frac{1}{3}$) and the type of loading(concentration loading, distribution loading). Results and conclusion : 1. In the fracture resistance experiment according to the finish line, the mean fracture strength of rounded shoulder(876N) and the mean fracture strength of chamfer(882N) did not skew any significant difference between each other(p>0.05). 2. The stress distribution of all ceramic crown in three dimensional finite element analysis showed concentration aspect at loading point and cervical area or labial surface. 3. In metal die, there were no differences in stress distribution between finish lines, but in natural teeth model, chamfer finish line showed higher stress than rounded shoulder finish line. 4. When force was loaded on the incisal edge the stress was concentrated on the incisal edge and the cervical area of labial surface. When force was loaded on the incisal $\frac{1}{3}$, the stress concentrated on the cervical area of labial surface and the cingulum area. 5. Generally, natural teeth model showed higher and various stress than the metal die.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.64-70
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• 2001

This work deals with the electrical conductivity of dielectric and cobalt percentage on output parameters such as metal removal rate and surface roughness value of sintered carbides cut by wire-electrical discharge machining (W-EDM). To obtain a precise workpiece with good quality, some extra repetitive finish cuts along the rough cutting contour are necessary. Experimental results show that increases of cobalt amount in carbides affects the metal removal rate and worsens the surface quality as a greater quantity of solidified metal deposits on the eroded surface. Lower electrical conductivity of the dielectric results in a higher metal removal rate as the gap between wire electrode and workpiece reduced. Especially, the surface characteristics of rough-cut workpiece and wire electrode were analyzed too. To obtain a good surface equality without cracks, 4 finish-cuts were necessary by reducing the electrical energy and the offset value.

• 대한기계학회논문집
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• 제5권4호
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• pp.338-346
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• 1981

Honing, lapping, polishing and superfinishing are applied for a precision machining to finish the metal surface, but these precision machining are micro-cutting by hard and micro-abrasive grains. Frictional machining is the new method to finish mirrorlike surface without using those abrasive grains. The frictional machining produces high pressure and high temperature instantly by compressing a tool material against the metal surface in sliding motion. The metal surface is given plastic deformation and plastic flow by the above mentioned frictional motion, but the surface roughness of the metal surface is influenced by physical and chemical reaction in surrounding atmosphere. Therefore, the atmosphere around the metal optimum atmosphere in the frictional machining. The part 1 of the study was performed in liquid atmospheres. Diesel oil, lubricant, grease, lard oil, bean oil and cutting fluid were used as such atmospheres. Medium carbon steel SM 50 C was used as a workpiece and ceramic tip was applied as a frictional tool. The result of the experiment showed characteristic machining conditions to generate the best surface roughness in each atmospheres.

• Journal of Mechanical Science and Technology
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• 제15권12호
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• pp.1676-1682
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• 2001

This work deals with the electrical conductivity of dielectric and cobalts percentage on output parameters such as metal removal rate and surface roughness value of sintered carbides cut by wire-electrical discharge machining (WEDM). To obtain a precise workpiece with good quality, some extra repetitive finish cuts along the rough cutting contour are necessary, Experimental results show that increases of cobalt amount in carbides affects the metal removal rate and worsens the surface quality as a greater quantity of solidified metal deposits on the eroded surface. Lower electrical conductivity of the dielectric results in a higher metal removal rare as the gap between wire electrode and workpiece reduced. Especially, the surface characteristics of rough-cut workpiece and wire electrode were analyzed too. To obtain a good surface equality without crack, 4 finish-cuts were necessary reducing fille electrical energy and the offset value.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.171-171
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• 2008

본 연구는 초음파 알루미늄 웨지 및 금 볼 본딩을 동시에 적용 가능한 본딩 Pad의 금속학적 안정성을 고려한 표층전극 형성 방법에 관한 것이다. 특히, 이동통신 및 전장용 모듈의 복합 및 융합화로 LTCC기판 패키징에 있어서 다양한 본딩 기술이 요구되고 있다. 전통적인 interconnection 기술인 Au ball 본딩 및 초음파 에너지를 이용한 Al wedge 본딩 기술이 동시에 사용되어야 하는 패키지 구조의 경우 본딩 패드의 표층전극 설계는 서로 상충되는 조건이 요구된다. 따라서, 본 연구에서는 LTCC기판의 표층전극의 Metal finish 방법으로 이용되는 ENEPIG(무전해 Ni/Pd/Au도금)공법으로 Au ball 본딩 및 초음파 Al wedge 본딩을 동시에 가능하게 하는 solution을 제시하여 패키징 자유도뿐만 아니라 Interconnection 신뢰성을 확보할 수 있었다.

• 구강회복응용과학지
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• 제19권3호
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• pp.219-237
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• 2003

he purpose of this study was to compare the fracture resistance of the IPS Empress ceramic crown with 1.0mm width rounded shoulder, which is usually recommended in all ceramic crown, and 0.5mm width chamfer finish lines on the maxillary first premolar. 30 sound maxillary first premolars were selected and then storaged in 5% NaOCl and saline. 15 teeth were performed preparation for each group(1.0mm rounded shoulder, 0.5mm chamfer). After 30 stone dies were made for each group, the IPS Empress ceramic crowns were fabricated and cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. LTD., Japan) on the natural teeth. The cemented crowns were mounted on the positioning jig and the universal testing machine(Zwick Z020, Zwick Co., Germany)was used to measure the fracture strength, with stress loading on the occlusal surface between buccal and lingual cusp. And also, three-dimensional finite element model was used to measure the stress distribution with two types of the finish lines(1.0mm rounded shoulder, 0.5mm chamfer) and two loading conditions(both buccal and lingual cusp inclination, lingual cusp inclination only). The result of the this study were as follows. In the fracture resistance experiment according to the finish line, the mean fracture strength of rounded shoulder(842N) showed higher value than that of the chamfer(590N) (p<0.05). In the three dimensional finite element analysis of all ceramic crown, metal die and natural teeth model did not show any differences in stress distribution between finish lines. Generally, when force was loaded on the occlusal inclination of buccal and lingual cusp, the stress was concentrated on the loading point and the central groove of occlusal surface. When force was loaded only on the occlusal inclination of lingual cusp, the stress was concentrated on the lingual finish line and loading point.

• 한국의류학회지
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• 제22권8호
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• pp.1060-1068
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• 1998

The effects of various catalysts and softners on the anti-crease finish of ramie with glyoxal were investigated. A number of metal salts commonly used as Lewis acid catalysts in DP finishing of cotton with formaldehyde and N-methylol agents were screened for glyoxal treatment of ramie fabric. Various organic and inorganic acids were mixed with Lewis acid catalyst as co-catalysts to improve catalytic activity. As a result, the combination of aluminum sulfate and citric acid was proven highly effective in catalyzing the crosslinking of ramie cellulose by glyoxal under lower curing temperature. With a mixed catalyst, performance properties, such as whiteness and tearing strength as well as wrinkle recovery of treated ramie fabric were improved as compared with that treated with aluminum sulfate alone. Additional improvement of tearing strength and wrinkle recovery was achieved by applying silicons softner in the treatment bath.

• 한국의상디자인학회지
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• 제2권2호
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• pp.137-154
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• 2000

The purpose of this study is to investigate the transition of luster material after the tweentieth century. This study was conducted by means of designer collection, journal of fashion, museum data, fabric exhibition and Internet data. The results of this study were as follows: Before the synthetic fiber period, the luster materials were used satin, chamuse, gauze, damask brocade and velvet, except cashmere, mohair and rayon. They are made from silk by the way of giving difference surface property. But since 1960s, it has used not only synthetic fiber with smooth surface but also vinyl, latex, natural leather, synthetic leather and metal. Luster material recently has a tendency to natural and soft shiny, example silket finish, chintz finish, silico coating finish with paper touch feel and so forth.

• 마이크로전자및패키징학회지
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• 제14권1호
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• pp.1-9
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• 2007

OSP(Organic Solderability Preservatives)표면처리는 저비용, 고신뢰성, 친환경 특성으로 기존의 금속계 표면처리인 Ni/Au 표면처리를 대체할 수 있는 공정으로 관심 받고 있다. 그러나, OSP는 저분자로 구성된 유기물이므로 여러 온도공정으로 구성된 전자패키지공정에서 제품의 변색이 필연적으로 발생하여 전체 양산수율에 미치는 영향은 매우 크다. 본 연구에서 OSP 처리된 제품을 전자패키지 공정별로 발생하는 변색수준에 따라서 시편을 분류 및 채취하여 변색원인분석 및 솔더조인트 특성평가를 수행하였으며, 기존의 표면처리공정인 Ni/Au 처리된 제품과 통계 적으로 비교 분석하였다. 따라서 변색원인에 대한 분석을 통하여 OSP 처리된 전자패키지 제품에 적용 시 발생하는 공정문제점에 대한 해결책을 제시하였다.

• 한국재료학회지
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• 제12권9호
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• pp.750-760
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• 2002

In this study, three solders, Sn-37Pb, Sn-3.5Ag, and Sn-3.8Ag-0.7Cu were screen printed on both electroless Ni/Au and OSP metal finished micro-via PCBs (Printed Circuit Boards). The interfacial reaction between PCB metal pad finish materials and solder materials, and its effects on the solder bump joint mechanical reliability were investigated. The lead free solders formed a large amount of intermetallic compounds (IMC) than Sn-37Pb on both electroless Ni/Au and OSP (Organic Solderabilty Preservatives) finished PCBs during solder reflows because of the higher Sn content and higher reflow temperature. For OSP finish, scallop-like $Cu_{6}$ /$Sn_{5}$ and planar $Cu_3$Sn intermetallic compounds (IMC) were formed, and fracture occurred 100% within the solder regardless of reflow numbers and solder materials. Bump shear strength of lead free solders showed higher value than that of Sn-37Pb solder, because lead free solders are usually harder than eutectic Sn-37Pb solder. For Ni/Au finish, polygonal shaped $Ni_3$$Sn_4$ IMC and P-rich Ni layer were formed, and a brittle fracture at the Ni-Sn IMC layer or the interface between Ni-Sn intermetallic and P-rich Ni layer was observed after several reflows. Therefore, bump shear strength values of the Ni/Au finish are relatively lower than those of OSP finish. Especially, spalled IMCs at Sn-3.5Ag interface was observed after several reflow times. And, for the Sn-3.8Ag-0.7Cu solder case, the ternary Sn-Ni-Cu IMCs were observed. As a result, it was found that OSP finished PCB was a better choice for solders on PCB in terms of flip chip mechanical reliability.