• 구강회복응용과학지
• /
• 제31권1호
• /
• pp.50-59
• /
• 2015

임플란트를 이용하여 심미 영역인 상악 전치부를 심미적, 기능적으로 수복하고 유지 관리하는 것은 어려운 일이다. 임플란트 주위염으로 인하여 치조골의 흡수, 치간유두의 수축 등과 같은 임플란트 주위 조직 문제와 금속 지대주의 노출로 인한 심미적 문제가 발생할 수 있기 때문이다. 본 증례에서는 기성지대주의 단점을 보완 가능한 맞춤형 지대주를 전통적인 제작 방식인 주조 방식으로 Co-Cr 합금을 이용하여 제작하고, 시멘트 유지형 보철물을 제작한 증례에 대해 보고하고자 한다.

• 대한기계학회논문집A
• /
• 제23권6호
• /
• pp.1011-1017
• /
• 1999

Electrolytic in-process dressing grinding technique which enables application of metal bond wheels with fine superabrasives in mirror surface grinding operations has developed. It is possible to make efficient precision machining of hard and brittle material such as ceramic and hard metal by the employment of this technique. However, in order to ensure the success of performances such as efficient machining, surface finish, and surface quality, it is important to sustain the insulating layer that has sharply exposed abrasives in wheel surface. Using AE(Acoustic Emission) sensor, this paper will show whether the insulating layer sustains stably or not in real grinding time. And by comparing AErms value and surface roughness their thresholds for stable electrolytic in-process dressing grinding will be determined.

• 한국분말재료학회지
• /
• 제13권5호
• /
• pp.351-359
• /
• 2006

Ni based($Ni_{57}Zr_{20}Ti_{18}Si_2Sn_3$) bulk metallic glass(BMG) powders were produced by a gas atomization process, and ductile Cu powders were mixed using a spray drying process. The Ni-based amorphous powder and Cu mixed Ni composite powders were compacted by a spark plasma sintering (SPS) processes into cylindrical shape. The relative density varied with the used SPS mold materials such as graphite, hardened steel and WC-Co hard metal. The relative density increased from 87% to 98% when the sintering temperature increased up to $460^{\circ}C$ in the WC-Co hard metal mold.

• 한국분말재료학회지
• /
• 제18권3호
• /
• pp.277-282
• /
• 2011

[ $LiCoO_2$ ] a cathode material for lithium rechargeable batteries, was prepared using recycled $Co_3O_4$. First, the cobalt hydroxide powders were separated from waste WC-Co hard metal with acid-base chemical treatment, and then the impurities were eliminated by centrifuge method. Subsequently, $Co_3O_4$ powders were prepared by thermal treatment of resulting $Co(OH)_2$. By adding a certain amount of $Li_2CO_3$ and $LiOH{\cdot}H_2O$, the $LiCoO_2$ was obtained by sintering for 10 h in air at $800^{\circ}C$. The synthesized $LiCoO_2$ particles were characterized by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) analysis.

• 한국생산제조학회지
• /
• 제24권6호
• /
• pp.594-598
• /
• 2015

The effects of Ni on the mechanical properties of WC-Xwt.%Ni-1.5wt.%Si-1.1wt.%$B_4C$ composite (X = 21.6, 23.6, 25.6 and 27.6 wt.%) were investigated in order to replace Co with Ni as the binder metal for hard materials based on WC-Co system. Using X-ray diffraction, optical microscopy, field-emission scanning electron microscopy results, the microstructure, pore distribution and grain size of the composites sintered at $1,150^{\circ}C$ were examined with different fraction (X = 21.6, 23.6, 25.6 and 27.6 wt.%) of binder metal Ni. The average WC grain size of the $WC-Ni-Si-B_4C$ composites was about $1{\mu}m$. The Rockwell hardness : A (HRA) and transverse rupture strength were about 88HRA and $110kgf/mm^2$, respectively. The obtained sample was bonded with SM45C at a temperature of $1,050^{\circ}C$. The thickness and mechanical properties of the bonded area were investigated with different dwell time at a bonding temperature of $1,050^{\circ}C$.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제6권3호
• /
• pp.21-29
• /
• 2001

양이온성 계면활성제인 HDTMA를 이용하여 치환시킨 유기 벤토나이트의 중금속 흡착능을 알아보았다. 카드뮴과 납의 흡착량은 pH와 흡착제 대 용액 비가 증가함에 따라 증가하였다. 이 실험을 통해 적정 pH 범위와 흡착제 대 용액 비를 결정하였다. 유기 벤토나이로의 중금속 흡착은 벤토나이트에 비해 약간 감소하였으며, 두 가지 중금속이 함께 존재하는 경우 경쟁에 의해 흡착량은 더 감소하였다. 유기 벤토나이트의 경우 카드뮴에 비해 납의 흡착 감소량은 더 두드러지게 나타났다. 이러한 흡착 mechanism을 hard-soft-acid-base (HSAB) 원리를 사용하여 설명하였다.

• Tribology and Lubricants
• /
• 제37권2호
• /
• pp.54-61
• /
• 2021

The effect of the sand blasting before TiAlN coating in the manufacture of WC hard metal alloy tips have been studied. For four different tips, according to the status of processing of the sand blasting and the coating, residual stress measurement by X-ray diffraction and several tests for mechanical properties have been conducted. The results suggest that there was no difference in static mechanical properties, such as hardness, surface roughness and elastic modulus, between two coatings. Furthermore, compressive residual stress was generated equally on their surfaces. Additionally, the compressive residual stress in substrate WC was found to increase greatly when subjected to sand blasting treatment. However, the compressive residual stress decrease after coating regardless of sand blasting treatment. Nevertheless, it is confirmed that the compressive residual stress generated in the coating after sand blasting is less than that in the non-sandblasting coating. This was attributed to the plastic deformation occurring in the WC substrate during coating after sand blasting. In contrast to the scratch test results, sand blasting was assumed to have a negative effect on the adhesion between the coating and substrate. This is because there is a high possibility of microcracks due to plastic deformation in the WC substrate under the coating after sand blasting.

• 구강회복응용과학지
• /
• 제30권1호
• /
• pp.81-92
• /
• 2014

상악 전치부에 임플란트를 이용해 심미적으로 수복 하는 것은 많은 어려움이 따른다. 이는 치조골 흡수와 치간 유두 수축 등과 같은 임플란트 주변 경, 연조직 문제와 금속지대주 및 금속도재관의 변연노출과 낮은 광투과도 등의 보철적 한계 때문이다. 이에 본 증례에서는 경, 연조직의 증대술 및 성형술, 발치 후 즉시 식립 등과 함께 임시수복물의 장기간 사용 및 수정으로 임플란트 주위 연조직의 형태와 건강을 형성한 후, 맞춤형 인상 코핑을 사용하여 이를 최종 모형에 재현하였다. 또한 맞춤형 지르코니아 지대주와 완전 도재관을 이용해 최종 수복함으로써 기능적이고 심미적인 결과를 얻었기에 이를 보고하고자 한다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제49권3호
• /
• pp.196-201
• /
• 2000

It is very important not only to detect PD signal but also to locate PD source in power cable line including its accessories. In this paper, the PID localization technique using interruption of metal sheath of cable or accessory is described. By interruption of metal sheath, the polarity of PD pulse to be measured on each part can be compared. With this technique, the exact location of PD in the accessory which has some defects can be found. Although the 'Soft' interruption method, that is, cable sheath is divided by semi-conductive layer with the resistance of higher than 1 k$\Omega$, was used instead of 'Hard' interruption method, it is also possible to detect exact location of PD. This technique is considered to be very effective for detecting PD localization in the type test of cable and accessories.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 추계학술대회 논문집
• /
• pp.272-272
• /
• 2009

Screen-printing metal contact is typically applied to the solar cells for mass production. And metal paste is used widely for rear contact formation of silicon solar cells. However, Screen-printing solar cell metal paste contact has low aspect ratio, low accuracy, high resistivity, hard control of unclean process. In this paper is to develop resistivity of rear contact for silicon solar cells applications. 4-point prove result, This resistivity of rear contact by Al evaporation was measured about $3.56{\times}10^6{\Omega}{\cdot}cm$ less than screen printed solar cell about $52.6{\times}10^6{\Omega}{\cdot}cm$.