• 제목/요약/키워드: gold alloy

검색결과 233건 처리시간 0.032초

S여대생(女大生)의 구강보건 실태조사 (A STUDY ON THE DENTAL HEALTH STATUS OF A COLLEGE GIRL STUDENTS)

  • 김정식
    • Restorative Dentistry and Endodontics
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    • 제6권1호
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    • pp.123-132
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    • 1980
  • The author conducted a dental survey of a college girl students and compared with that of E college students 10 years ago which based on the same criteria. The items of this survey included the prevalence of dental caries, DMFT and the kinds of restored material. All college students 1,414 were examined in May 1978, with the recommended criteria and method of W.H.O.. Among them, the data of 1,393 were analyzed for this study. The following results were obtained: 1. The average number of present teeth were 28.97${\pm}$1.64. 2. The prevalence of dental caries was 84.92% and D.M.F. index was 15.51. Average D.M.F. teeth were 4.49${\pm}$3.69. 3. The average number of decayed (D) teeth were 2.09${\pm}$2.16. 4.30% of the present decayed teeth was secondary decay, and 2.44% of the decayed teeth was indicated for extraction. 4. The average number of missing(M) teeth were 0.32${\pm}$0.79. It included 8.56% of root fragements. 5. Average number of filled(F) teeth were 2.09${\pm}$3.17. F-ratio of this group was 46.45%. The analysis revealed 50.88% of amalgam alloy, 31.41% of gold inlays, and 1.20%, the least among the filling materials, silicate cement or composite resin. 6. While the prosthodontic treatment, such as crown and bridge has reduced than that of 10 years ago, the fillings and inlays as the conservative means has increased.

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Highly Productive Process Technologies of Cantilever-type Microprobe Arrays for Wafer Level Chip Testing

  • Lim, Jae-Hwan;Ryu, Jee-Youl;Choi, Woo-Chang
    • Transactions on Electrical and Electronic Materials
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    • 제14권2호
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    • pp.63-66
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    • 2013
  • This paper describes the highly productive process technologies of microprobe arrays, which were used for a probe card to test a Dynamic Random Access Memory (DRAM) chip with fine pitch pads. Cantilever-type microprobe arrays were fabricated using conventional micro-electro-mechanical system (MEMS) process technologies. Bonding material, gold-tin (Au-Sn) paste, was used to bond the Ni-Co alloy microprobes to the ceramic space transformer. The electrical and mechanical characteristics of a probe card with fabricated microprobes were measured by a conventional probe card tester. A probe card assembled with the fabricated microprobes showed good x-y alignment and planarity errors within ${\pm}5{\mu}m$ and ${\pm}10{\mu}m$, respectively. In addition, the average leakage current and contact resistance were approximately 1.04 nA and 0.054 ohm, respectively. The proposed highly productive microprobes can be applied to a MEMS probe card, to test a DRAM chip with fine pitch pads.

A STUDY ON MECHANICAL PROPERTIES OF TiN, ZrN AND WC COATED FILM ON THE TITANIUM ALLOY SURFACE

  • Oh, Dong-Joon;Kim, Hee-Jung;Chung, Chae-Heon
    • 대한치과보철학회지
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    • 제44권6호
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    • pp.740-750
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    • 2006
  • Statement of problems. In an attempt to reduce screw loosening, dry lubricant coatings such as pure gold or tefron have been applied to the abutment screw. However, under repeated tightening and loosening procedures, low wear resistance and adhesion strength of coating material produced free particles on the surface of abutment screw and increased frictional resistance resulting in screw tightening problems. Purpose. The aim of this study was to compare friction coefficient, adhesion strength, vickers hardness and evaluate coating surface of titanium alloy specimens coated with TiN(titanium nitride), ZrN(zirconium nitride) and WC(tungsten carbide). Material and method. Titanium alloy(Ti-6Al-4V) discs of 12mm in diameter and 1mm in thickness divided into 4 groups. TiN, ZrN and WC was coated for the specimens of 3 groups respectively, and those of 1 group were not coated. Each group was made up of 4 specimens. In this study, sputtering method was used among the PVD(Physical Vapor Deposition) techniques available for TiN, ZrN and WC coatings. Friction coefficient, adhesion strength, vickers hardness and coating surface of 4 groups were measured. Results. 1. For all three coating conditions, friction coefficient was significantly decreased. Especially, ZrN coated surface showed the lowest value. $TiN(0.39{\pm}0.02)$, $ZrN(0.24{\pm}0.01)$, $WC(0.31{\pm}0.03)$. 2. TiN coating showed the highest adhesion strength, however ZrN coating had the lowest value. $TiN(25.3N{\pm}1.6)$, $ZrN(14.8N{\pm}0.6)$, $ WC(18.4N{\pm}0.7)$. 3. Vickers hardness of all three coatings was remarkably increased as compared with that of none coated specimen. TiN coating had the highest Vickers hardness, however WC coating showed the lowest value. $TiN(1865.2{\pm}33.8)$, $ZrN(1814.4{\pm}18.6)$, $WC(1008.5{\pm}35.9)$. 4. The ZrN or WC coated specimen showed a homogeneous and smooth surface, however the rough surface with defects was observed for TiN coating. Conclusions. When TiN, ZrN and WC coating applied to the abutment screw, frictional resistance would be reduced, as a result, the greater preload and prevention of the screw loosening could be expected.

부여 규암리 출토 금동관음보살 입상의 형상과 제작기법 (Gilt-bronze Standing Avalokiteshvara from Gyuam-ri, Buyeo: The Structure and Production Technique)

  • 신용비;김지호
    • 박물관보존과학
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    • 제23권
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    • pp.1-16
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    • 2020
  • 이 논문에서는 부여 규암리 출토 '금동관음보살입상(국보 제293호, M335번)' 1점을 현미경으로 확대 관찰하여 제작기법을 확인하였고, XRF 성분분석과 Hard X-선 조사로 구성 성분과 불상 표면 처리 방법, 주조법을 확인하였다. 이 불상은 연화대좌 위에 직립하는 보살상이다. 불상 양 측면으로 흘러내린 천의와 대좌에 표현된 연화문의 모양을 볼 때 7세기 이후에 만들어진 불상의 특징을 하고 있다. 대좌 안쪽에서 내형과 외형을 고정시키기 위한 틀잡이와 주물의 주입 흔적이 관찰되었다. 또한, 주조기법은 팔과 대좌 부분에 청동 주물시 형성된 기포가 확인되어 이를 종합해 볼 때 고대 중소형 금동불 제작에 많이 사용되는 밀납주조법으로 제작한 것으로 판단된다. 성분분석 결과, 불상 내부에서는 시기적으로 6~7세기에 많이 나타나는 구리(Cu)-주석(Sn)-납(Pb) 계열의 3원계 합금을 사용한 것으로 확인되며 이는 금속을 합금하여 주조를 쉽게 하고 불상에 표현된 문양 및 장식을 선명하게 표현하고자 하는 의도로 추정된다. 불상 표면에서는 수은(Hg)이 검출되어 금(Au)을 수은(Hg)에 용해시켜 도금하는 방식인 아말감도금기법을 사용했던 것으로 추정되며 이러한 도금방법은 고대 한반도에서 제작된 소형 금동불에서 주로 확인되는 불상의 도금 방식이다.

알칼리 수용액에서 산소환원반응에 대한 다공성 AuCu 덴드라이트 표면의 전기화학적 특성 평가 (Electrochemical properties of porous AuCu dendrite surface for the oxygen reduction reaction in alkaline solutions)

  • 김민영;이종원;조수연;박다정;정현민;이주열;이규환
    • 한국표면공학회지
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    • 제54권1호
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    • pp.1-11
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    • 2021
  • Porous dendrite structure AuCu alloy was formed using a hydrogen bubble template (HBT) technique by electroplating to improve the catalytic performance of gold, known as an excellent oxygen reduction reaction (ORR) catalyst in alkaline medium. The rich Au surface was maximized by selectively electrochemical etching Cu on the AuCu dendrite surface well formed in a leaf shape. The catalytic activity is mainly due to the synergistic effect of Au and Cu existing on the surface and inside of the particle. Au helps desorption of OH- and Cu contributes to the activation of O2 molecule. Therefore, the porous AuCu dendrite alloy catalyst showed markedly improved catalytic activity compared to the monometallic system. The porous structure AuCu formed by the hydrogen bubble template was able to control the size of the pores according to the formation time and applied current. In addition, the Au-rich surface area increased by selectively removing Cu through electrochemical etching was measured using an electrochemical calculation method (ECSA). The results of this study suggest that the alloying of porous AuCu dendrites and selective Cu dissolution treatment induces an internal alloying effect and a large specific surface area to improve catalyst performance.

수종의 인공 레진 치아의 마모저항성과 경도에 관한 비교 연구 (Comparative Study on Wear Resistance and Hardness of Several Artificial Resin Teeth)

  • 최유성;이준석;조인호
    • 구강회복응용과학지
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    • 제24권2호
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    • pp.129-146
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    • 2008
  • 본 연구에서는 다양한 치과 수복재료에 대합되는 의치용 레진치의 마모저항성을 알아보기 위해 통상의 아크릴 릭 레진치인 $Trubyte^{(R)}$ $Biotone^{(R)}$ (Dentsply, U.S.A.)과 고강도 레진치인 Endura $Posterio^{(R)}$ (Shofu, Japan), Physio $Duracross^{(R)}$ (Nissin, Japan)를 수복재료인 금합금, 도재, 충전용 레진에 대합시켜 마모저항성을 비교 분석하였다. 또한 앞의 세 종류의 레진 인공치와 5종류의 의치세정제인 유한락스, 폴리덴트, 싸이덱스, 헥사메딘, 증류수를 사용하여 의치세정제 및 소독제가 경도에 미치는 영향을 비교 분석하여 다음과 같은 결과를 얻었다. 1. 대합되는 수복재료로 충전용 레진, 도재를 사용한 경우 $Trubyte^{(R)}$ $Biotone^{(R)}$, Endura $Posterio^{(R)}$, Physio $Duracross^{(R)}$ 순으로 교두정 높이감소가 컸으며 세 재료간의 유의한 차이를 보였다 (p<0.05). 2. 대합되는 수복재료로 금합금을 사용한 경우 $Trubyte^{(R)}$ $Biotone^{(R)}$, Endura $Posterio^{(R)}$, Physio $Duracross^{(R)}$ 순으로 교두정 높이 감소가 컸으며, 특히 $Trubyte^{(R)}$ $Biotone^{(R)}$ 이 다른 두 종류의 인공치보다 유의성 있게 높은 교두정 높이 감소를 보였다 (p<0.05). 3. 대합되는 수복재료로 충전용 레진, 금합금, 도재를 사용한 경우 모두 $Trubyte^{(R)}$ $Biotone^{(R)}$, Endura $Posterio^{(R)}$, Physio $Duracross^{(R)}$ 순으로 무게 감소가 컸으며, 세 재료간의 유의한 차이를 보였다 (p<0.05). 4. 의치세정제에 따른 경도 감소는 실험 전과 후의 측정치를 비교했을 때 모든 레진 인공치에서 유의성 있는 차이 를 나타내었다 (p<0.05). 5. 유한락스, 싸이덱스, 헥사메딘에 담구었던 레진 인공치에 의한 경도감소는 $Trubyte^{(R)}$ $Biotone^{(R)}$, Endura $Posterio^{(R)}$, Physio $Duracross^{(R)}$ 순으로 높은 감소를 보였고, 특히 $Trubyte^{(R)}$ $Biotone^{(R)}$이 다른 두 종류의 인공치보다 유의성 있게 높은 경도 감소를 보였다 (p<0.05). 이상의 실험 결과 마모저항성 실험에서는 최근에 개발된 Physio $Duracross^{(R)}$가 다른 두 종류의 레진 인공치에 비해 세 종류의 대합되는 수복재료 모두에서 높은 마모저항성을 보였고 특히 $Trubyte^{(R)}$ $Biotone^{(R)}$에 비해 유의성 있게 높은 마모저항성을 보였다. 경도 실험에서는 Physio $Duracross^{(R)}$와 Endura $Posterio^{(R)}$$Trubyte^{(R)}$ $Biotone^{(R)}$에 비해 유의성 있게 낮은 경도감소를 보였고 (p<0.05), 폴리덴트, 증류수에서는 유의한 차이를 보이지 않았다. 따라서, Physio $Duracross^{(R)}$가 세 종류의 레진 인공치에 비해 우수한 마모저항성을 보인다고 볼 수 있고, Endura $Posterio^{(R)}$와 함께 $Trubyte^{(R)}$ $Biotone^{(R)}$에 비해서 우수한 경도를 보인다고 볼 수 있지만, 단편적인 실험 결과이므로, 아직은 신중하게 고려되어야 하고, 더 많은 연구가 필요하다고 사료된다.

금대체를 위한 치과주조용 파라듐 합금의 표면특성 (Surface Characteristics of Dental Casting Palladium Alloy for Replacement of Gold Alloy)

  • 박선영;황인조;유지민;박민규;임상규;배호성;최한철
    • 한국표면공학회:학술대회논문집
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    • 한국표면공학회 2016년도 추계학술대회 논문집
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    • pp.196-196
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    • 2016
  • 치과나 기공소로부터 높은 원가로 인한 재료선택에 어려움을 겪고 있어 귀금속 금합금의 물성을 가질 수 있도록 하면서 가격급등으로 인한 문제 해결하기 위한 비귀금속 합금으로 대체가 필요하기에 이에 따른 연구가 이루어져 국산 제품의 상품화를 위해 파라듐을 이용하여 적합한 새로운 합금을 개발하는 것이 필요하다. 치과용 골드합금은 미국치과의사 협회의 구정에 의하면 1형부터 4형까지 분류하고 있으며 3형에 해당하는 강도와 기계적인 특성을 갖도록 파라듐으로 대체하는 연구가 진행중이거나 시판되고 있다. 따라서 본 연구에서는 2형, 3형 및 4형을 대체가능하도록 팔라듐을 기반으로 한 새로운 합금을 설계하고 합금의 성분원 소인 Au(1~5), Pd(20~25), Ag(70~75), In(1.5) 및 Zn(2)등으로 조성을 변화시켜 측량 후 합금을 제조하기 위하여 아르곤 분위기하의 진공아크용해로를 이용하여 용해하였다. 정량된 금속을 진공아크 용해로에 장입하고 용해는 균질한 합금이 되도록 최소한 6회 이상 용융을 실시하며 합금성분의 손실이 발행하지 않도록 보정을 하였다. 합금의 미세조직 관찰을 위하여 샘플을 고속 다이아몬드 정밀 절단기(Acculom-5, STRUERS, Denmark)를 이용하여 절단한 후 2000 grit의 Sic 연마지에서 단계적으로 $0.3{\mu}m$ 알루미나 분말까지 연마한 후 초음파 세척을 하였다. 준비한 시편은 KCN과 $(NH_4)_2S_2O_8$을 1:1로 혼합한 부식액으로 에칭한 후 OM과 SEM을 이용하여 조직을 관찰하였으며 각 샘플의 성분변화는 EDS 분석을 통해 확인하고 결정구조는 XRD를 사용하여 분석하였다. 경도시험은 비커스경도시험기를 이용하여 5kg의 하중을 30초간 작동시켜 압흔을 연결된 micron으로 평균값을 측정하였다. 각 시편의 부식거동은 POTENTIOSTAT(Model PARSTAT 2273, EG&G, USA)을 이용하여 구강 내환경화 유사한 $36.5{\pm}1^{\circ}C$의 0.9% NaCl에서 실시하였다. 인가전위는 -1500mV에서 1000mV까지 1.67 mV/min의 주사속도로 인가하여 시험을 수행하였으며 분극곡선으로부터 부식전위와 부식전류밀도 및 부동태영역의 전류밀도로 금속의 용출거동을 조사하였으며 부식이 끝난 시편은 FE-SEM과 EDS를 사용하여 조사하였다. 기계적인 특성은 Pd-Ag에 3wt%의 Au를 첨가한 합금이 Pd-Ag에 1.5wt%합금을 첨가한 경우에 비하여 기계적인 특성이 증가하고 내식성이 크게 증가하였다. 이들 합금에 Cu를 11wt%를 첨가한 경우는 비커스경도가 200이상으로 높게 나타났지만 내식성이 크게 감소하였다.

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납착법과 레이저융합법이 치과용 합금의 부식에 미치는 영향 (THE EFFECT OF SOLDER AND LASER WELD ON CORROSION OF DENTAL ALLOYS)

  • 백진;우이형;최대균;최부병
    • 대한치과보철학회지
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    • 제43권2호
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    • pp.264-279
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    • 2005
  • Statement of problem. Intraoral corrosion not only affects the esthetic and function of metallic dental restoration, but also has biologic consequences as well. Therefore, corrosion is considered a primary factor when choosing the dental alloy and laboratory technique. Purpose. The objective of this study was to compare the effects of solder and laser weld on corrosion Material and methods. Test specimens were made of 2 types of gold alloys, Co-Cr and Ni-Cr alloy and fabricated 3 methods, respectively: as cast, solder, and laser weld. For the analysis of corroding properties, potentiodynamic polarization test and immersion test conducted. The potentiodynamic polarization scan curve were recorded in 0.9% NaCl solution(pH 7) using Potentiostat/Galyanostat Model 273A. All specimens were exposed to 0.9% NaCl solution(pH 2.3) during 14 days. Elemental release into corrosive solution was measured by atomic emission spectrometry Differences in corrosion potential and mass release were determined using ANOVA. Results and conclusion. Through analyses of the data, following results were obtained. 1. In Pontor MPF and Wiron 99, corrosion potential of the solder group was statistically lower than as cast and laser weld group (p<0.05) , but there was no difference between corrosion potential of solder group and laser weld group in Pontor MPF and no differences between as cast and laser weld group (p>0.05). In Jel-Bios 10 and Wirobond, there was no difference of corrosion potential according to joining methods(p>0.05). 2. In all tested alloys, the amount of released metallic ion was greatest in the solder group(p<0.05). There was no difference between as cast group and laser weld group in Jel-Bios 10 and Wirobond(p>0.05). 3. In scanning electron microscopic examination. except soldered Wiron 99 specimens, it is impossible to discriminate the corrosive property of solder and laser weld. 4. Under the this experimental circumstances, laser weld appears superior to the solder when corrosion is considered.

캔틸레버의 길이와 하중이 하악 임플랜트지지 고정성 보철물의 응력 분산에 미치는 영향 (EFFECT OF CANTILEVER LENGTH AND LOAD ON STRESS DISTRIBUTION OF FIXED IMPLANT-SUPPORTED PROSTHESES)

  • 태윤섭;이화영;조혜원
    • 대한치과보철학회지
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    • 제36권4호
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    • pp.615-643
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    • 1998
  • The purpose of this study was to evaluate the effect of cantilever length, load, and implant number on the stress distribution of implant supported fixed prosthesis. In the replica of an edentulous human mandible, four or five implants were placed and spaced evenly between the mental foramina and symmetrical gold alloy cast superstructures with cantilever were fabricated. Strain gauges were placed in buccal and lingual side of implants. 9, 15, 21kg of loads at varying cantilever lengths were applied to the occlusal surface of fixed prostheses. The strains were recorded from each gauge and principal stresses were calculated The results were as follows : 1. Increasing the length of the cantilever increased the stresses on the bone supporting implants. and the ratio of increase became high as increasing the load. 2. In the model with four implants, the highest compressive stress was measured on lingual side of the first implants nearest loading point and the highest tensile stress was measured on buccal side of the second implants. 3. In the model with five implants, the highest compressive stress was measured on lingual side of the first implants nearest loading point. And the highest tensile stress was measured on buccal side of the second implants, and lingual side of the third implants. 4. There was no significant change of the magnitude of stress on the most distal imp]ant of non cantilevered side as increasing the cantilever length or load. 5. In general, the superstructure supported by five implants reduced the stress and was less affected by cantilever length compared to the support provided by four implants.

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연결방법에 따른 주조체 변위에 관한 3차원적 비교연구 (THREE-DIMENSIONAL COMPARISON OF FRAMEWORK DISPLACEMENTS JOINED BY VARIOUS CONNECTION TECHNIQUES)

  • 임장섭;전영찬;정창모
    • 대한치과보철학회지
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    • 제37권3호
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    • pp.358-374
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    • 1999
  • This study measured the relative displacements of the five-unit fixed partial dentures as cast with the same fixed partial dentures sectioned and assembled by investment-soldering, solder-ing stand-soldering, and cast-joining techniques A total of fifteen specimens using a type IV gold alloy were one-piece cast as control and then sectioned and assembled five test specimens for each method were prepared. A computerized three dimensional coordinate measuring machine and specially designed cylinder for this study were used. Displacement was defined by six displacement variables for the each of cylinders incorporated in each casting: three component displacements(${\Delta}Lx,\;{\Delta}Ly,\;and\;{\Delta}Lz$) and rotational displacements(${\Delta}{\theta}x,\;{\Delta}{\theta}y,\;{\Delta}{\theta}z$). The global displacement was computed using the mathematical formula ${\Delta}R$ = Global displacement =$\sqrt{{(x'-x)}^2+{(y'-y)}^2+{(z'-z)}^2}$ Under the conditions of this study, the following conclusions were drawn: 1. The investment-soldering group showed the largest mean value of final global displacements, followed by stand-soldering group, cast-joining group and one-piece cast group. However, between the mean values of final global displacement for the cast-joining group and one-piece cast group, there was no significant difference. 2. For investment-soldering and stand-soldering groups, the greater global displacements were recorded in soldering phase than in indexing or investing phase. 3. For one-piece cast group, the displacements occured mostly in the casting phase. And for cast-joining group, there was no significant difference in global displacements among the fabricating procedures. 4. Intercentroidal distance decreased in framework-patterning, solder-indexing, solder-standing, and soldering phases, but increased in investment block-investing and casting phases. 5 Specially designed cylinder for touch-trigger type coordinate measuring machine was validated.

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