• Journal of Periodontal and Implant Science
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• 제46권6호
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• pp.362-371
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• 2016

Purpose: The increasing demand for esthetically pleasing results has contributed to the use of ceramics for dental implant abutments. The aim of this study was to compare the biological response of epithelial tissue cultivated on lithium disilicate ($LS_2$) and zirconium oxide ($ZrO_2$) ceramics. Understanding the relevant physicochemical and mechanical properties of these ceramics will help identify the optimal material for facilitating gingival wound closure. Methods: Both biomaterials were prepared with 2 different surface treatments: raw and polished. Their physicochemical characteristics were analyzed by contact angle measurements, scanning white-light interferometry, and scanning electron microscopy. An organotypic culture was then performed using a chicken epithelium model to simulate peri-implant soft tissue. We measured the contact angle, hydrophobicity, and roughness of the materials as well as the tissue behavior at their surfaces (cell migration and cell adhesion). Results: The best cell migration was observed on $ZrO_2$ ceramic. Cell adhesion was also drastically lower on the polished $ZrO_2$ ceramic than on both the raw and polished $LS_2$. Evaluating various surface topographies of $LS_2$ showed that increasing surface roughness improved cell adhesion, leading to an increase of up to 13%. Conclusions: Our results demonstrate that a biomaterial, here $LS_2$, can be modified using simple surface changes in order to finely modulate soft tissue adhesion. Strong adhesion at the abutment associated with weak migration assists in gingival wound healing. On the same material, polishing can reduce cell adhesion without drastically modifying cell migration. A comparison of $LS_2$ and $ZrO_2$ ceramic showed that $LS_2$ was more conducive to creating varying tissue reactions. Our results can help dental surgeons to choose, especially for esthetic implant abutments, the most appropriate biomaterial as well as the most appropriate surface treatment to use in accordance with specific clinical dental applications.

• 한국표면공학회지
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• 제46권2호
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• pp.68-74
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• 2013

For the coating of diamond films on WC-Co tools, a buffer interlayer is needed because Co catalyzes diamond into graphite. W and Ti were chosen as candidate interlayer materials to prevent the diffusion of Co during diamond deposition. W or Ti interlayer of $1{\mu}m$ thickness was deposited on WC-Co substrate under Ar in a DC magnetron sputter. After seeding treatment of the interlayer-deposited specimens in an ultrasonic bath containing nanometer diamond powders, $2{\mu}m$ thick nanocrystalline diamond (NCD) films were deposited at $600^{\circ}C$ over the metal layers in a 2.45 GHz microwave plasma CVD system. The cross-sectional morphology of films was observed by FESEM. X-ray diffraction and visual Raman spectroscopy were used to confirm the NCD crystal structure. Micro hardness was measured by nano-indenter. The coefficient of friction (COF) was measured by tribology test using ball on disk method. After tribology test, wear tracks were examined by optical microscope and alpha step profiler. Rockwell C indentation test was performed to characterize the adhesion between films and substrate. Ti and W were found good interlayer materials to act as Co diffusion barriers and diamond nucleation layers. The COFs on NCD films with W or Ti interlayer were measured as less than 0.1 whereas that on bare WC-Co was 0.6~1.0. However, W interlayer exhibited better results than Ti in terms of the adhesion to WC-Co substrate and to NCD film. This result is believed to be due to smaller difference in the coefficients of thermal expansion of the related films in the case of W interlayer than Ti one. By varying the thickness of W interlayer as 1, 2, and $4{\mu}m$ with a fixed $2{\mu}m$ thick NCD film, no difference in COF and wear behavior but a significant change in adhesion was observed. It was shown that the thicker the interlayer, the stronger the adhesion. It is suggested that thicker W interlayer is more effective in relieving the residual stress of NCD film during cooling after deposition and results in stronger adhesion.

• 마이크로전자및패키징학회지
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• 제30권4호
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• pp.105-111
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• 2023

차세대 전자기기는 기계적인 굽힘이나 말림(rolling) 변형이 반복적으로 가능한 형태로 발전하고 있다. 이에 따라 전자기기 내부 소자들 간의 연결을 위한 금속 배선의 기계적인 신뢰성 확보가 필수적이며, 특히, 실제 사용 환경을 모사한 압축 환경에서의 굽힘 피로 변형에 대한 신뢰성 평가가 중요하다. 본 연구에서는 구리(Cu)와 폴리이미드(Polyimide, PI) 기판 간의 접착력을 향상시키고, 굽힘 피로 변형 환경에서 구리 배선의 신뢰성을 높이기 위한 방법을 탐구했다. 접착력 향상을 위해 폴리이미드 기판에 산소 플라즈마 처리와 크롬(Cr) 접착층 도입이라는 두 가지 방법을 적용하고, 이들이 압축 상황에서의 피로 거동에 미치는 영향을 비교 분석했다. 연구 결과, 접착력 향상 방법에 따라 압축 피로 거동에서 차이가 발생하는 것을 확인했다. 특히, 크롬 접착층을 도입한 경우 1.5% 변형률에서는 크랙 생성이 주된 변형 메커니즘이며, 피로 특성이 취약한 결과를 얻었으나, 2.0%의 높은 변형률에서는 플라즈마 처리법에 비해 박리가 발생하지 않아 가장 개선된 피로 특성을 나타냈다. 본 연구의 결과는 유연 전자기기의 사용 환경에 적합한 피로 저항 개선법을 제시하고, 크랙 발생 정도를 포함한 전자기기의 신뢰성 향상에 중요한 정보를 제공할 수 있을 것으로 기대한다.

• 접착 및 계면
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• 제4권1호
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• pp.1-8
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• 2003

본 연구에서는 이관능성 에폭시와 PMR-15 블렌드계의 접촉각 측정과 파괴인성 측정을 통하여 PMR-15 조성비에 따른 표면자유에너지가 기계적 계면특성에 미치는 영향에 대하여 고찰하였다. 블렌드계의 FT-IR 분석 결과, PMR-15의 이미드화에 따른 특성 밴드가 1,722, $1,778cm^{-1}$ (C=O)와 $1,372cm^{-1}$ (C-N)에서 나타났고, 에폭시의 개환 반응에 따른 -OH peak는 PMR-15 phr의 함량에서 가장 크게 나타나는 것을 확인할 수 있었다. 증류수와 diiodomethane을 젖음액으로 사용하여 sessile drop 방법으로 접촉각을 측정한 결과, 표면자유에너지는 극성 요소의 증가에 의해서 PMR-15의 함량이 10 phr일 때 최고값을 나타내었다. 또한, 기계적 계면특성을 파괴인성 측정을 통하여 알아본 결과 $K_{IC}$와 $G_{IC}$ 또한 표면자유에너지와 유사한 경향을 나타내는 것을 알 수 있었는데, 이는 PMR-15 10 phr의 조성에서 수소결합의 증가에 의한 블렌드계의 극성요소가 증가함에 따라 분자들간의 계면결합력이 증가했기 때문인 것으로 관찰된다.

• 동력기계공학회지
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• 제18권6호
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• pp.58-63
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• 2014

This paper deals with the effects of counterpart materials on the wear behavior of thermally sprayed STS316 coatings. STS316 powders were flame-sprayed onto a carbon steel substrate. Dry sliding wear tests were performed using the applied loads of 15 N. AISI52100, $Al_2O_3$, $ZrO_2$ and $Si_3N_4$ balls were used as counterpart materials. Wear behavior of STS316 coatings against different counterpart materials were studied using a scanning electron microscope(SEM) and energy dispersive X-ray spectroscopy (EDS). The results show that the wear behavior of thermally sprayed STS316 coatings strongly depends on the type of counterpart material. Dominant wear mechanism was similar for all studied materials as failure of adhesion film except for Si3N4 used as counterpart material. In the case of Si3N4 used as counterpart material, dominant wear mechanism was abrasion.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 봄 학술발표회 논문집
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• pp.132-134
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• 2003

직물에 부직포 심지를 부착하면, 각각 단독으로 있을 때와는 다른 새로운 특성을 나타내게 되고, 그러한 복합재료의 역학적 성질들을 그것의 구성성분들의 성질들로부터 예견하려는 시도가 많이 행해지고 있다. 이에 대해서는 복합재료와 구성성분들의 역학적 성질들 비교[1,2]에서부터 구성성분들의 역학적 성질들의 합에 가중치를 적용해서 구성성분들과 복합재료의 역학적 성질들의 상관관계를 구하려는 노력[3,4,5], 구성성분들 뿐만 아니라 접착제의 상태가 최종 복합재료의 역학적 성질에 미치는 영향에 대한 연구[6,7]까지 다양한 관점에서 연구가 행해지고 있다. (중략)

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 봄 학술발표회 논문집
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• pp.293-294
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• 2003

견 피브로인은 대표적인 섬유상 단백질의 하나로 생체적합성, 생분해성, 저독성 등의 유용한 특성을 가지므로 생체재료로 상당한 관심과 연구의 대상이 되어왔다. 우리는 최근의 연구에서 견 피브로인을 생사로부터 추출한 다음, 포름산을 용제로 하여 전기방사함으로써 나노섬유를 제조하고 이들의 각화세포에 대한 친화력을 확인한 바 있다. 본 연구에서는 견 피브로인의 구조체를 나노섬유 부직포, 필름, 마이크로 섬유로 구성된 직물 둥의 형태로 하여 그들의 2차 구조를 비교함과 동시에 구조적 특성이 각화세포와의 친화력에 어떠한 영향을 미치는 가를 비교ㆍ검토 하고자 하였다. (중략)

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 제35회 춘계학술대회
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• pp.179-184
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• 2002

Adhesive contact characteristics of torus-shaped bumps, which are commonly used to reduce friction and stiction in hard disks, are analyzed to examine the applicability to the MEMS structure. The analysis is conducted with the finite element technique considering the adhesive force. Torus-shaped bumps of various rim and bump radii are analyzed. The jump-to-contact behavior, adhesion hysterisis, pull-off forces, contact region and pressure, and surface and subsurface stresses are presented and discussed. Analysis results in the absence of adhesive force are also presented to identify the effect of adhesive force.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.171-172
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• 2023

In order to reduce crack defects caused by the behavior of concrete during floor tile construction, this paper introduced a hybrid floor adhesion system that first constructs an organic adhesive with crack correspondence and attaches tiles with inorganic mortar.

• 펄프종이기술
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• 제43권3호
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• pp.121-127
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• 2011

This study used two types of rheology modifiers including an alkali-swellable emulsion (ASE) and an surface-adhesion emulsion (SAE) to elucidate their effects on high shear viscosity and dynamic penetration behavior among the flow properties of high solids coating. Since rheology under high shear and dynamic penetration behavior significantly affect the quality of coated paper in case of high solids coating, it is very important to examine the variations in rheology of high solids coating color by rheology modifier. It was found that the high solids coating color prepared with the SAE type showed superior dynamic penetration behavior and high shear viscosity than that with the ASE type rheology modifier.