• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.813-816
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• 2004

This study was performed to investigate bonding performance of epoxy resins for repairing of cracks in concrete, as a part of project to establish quality control standard for epoxy resins. In the slant shear strength test for hard and soft type epoxy, hard type was higher about 3 times than soft one. From the results, it is thought that hard type is suitable for load carrying. Injection of epoxy resin in the notch made flexural strength increase about $47\%$ over the specimen that epoxy resin is not injected. There were no differences in bonding performances with viscosity. Application of epoxy resin on the wet concrete surface made slant shear strength decrease about $46\%$, but similar performance to the case of application on the dry surface appeared by using epoxy resin for wet condition.

• 한국세라믹학회지
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• 제26권3호
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• pp.371-380
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• 1989

The purpose of this experiment is to elucidate the reaction mechanism concerning to the formation of crystalline BaTiO3 synthesized by adding the pH control agent(KOH soln) in TiCl4 and BaCl2 solution (Wet direct synthetic method). In this expeirment, it is identified that the amorphous barium-titanate having Ba-O-Ti bonding is formed above pH5 due to the -OH- ion and Ti-gel is formed below pH5 due to the polymerization of metatitanic acid. The bonding of the amorphous Ba-O-Ti is identified by FT-IR spectrum and crystallization temperature is about 82$0^{\circ}C$. If the pH of the above system according to the -OH- ion concentration is above 13.8, the polymerized metatitanic acid will be depolymerized and produce [TiO3]2+ion and crystalline BaTiO3 is formed by reacting the produced [TiO3]-- ion with the active Ba++ ion.

• Journal of the Korean Wood Science and Technology
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• 제38권2호
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• pp.117-123
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• 2010

The objective of this research was executed to investigate the effect of molar ratio of formaldehyde to urea and melamine (F/(U+M)) of urea-melamine-formaldehyde (UMF) resin on bonding high and low moisture content veneers. For that purpose, UMF resin types with 5 different F/(U+M) molar ratios (1.45, 1.65, 1.85, 2.05, and 2.25) synthesized were used in present study. First, their curing behavior was evaluated by differential scanning calorimetry. Second, their adhesion performance in bonding high and low moisture content veneers was evaluated by probe tack and dry and wet shear strength tests. Curing temperature and reaction enthalpy decreased with the increase of F/(U+M) molar ratio. And the dry and wet shear strengthsof plywood manufactured from low moisture content veneers were higher than thoseof plywood manufactured from high moisture content veneers. Also, the maximum initial tack force on the low moisture content veneer was higher than that on the high moisture content veneer.

• 펄프종이기술
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• 제34권5호
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• pp.56-62
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• 2002

Alternative way of shaping fibers suitable for papermaking was introduced. Impact refining, which was done simply by hitting wet fibers with a metal weight vertically, was intended to keep the fibers from shortening and to cause mostly internal fibrillation. Virgin chemical pulp, its recycled one and OCC were used in the experiment. It was noticed from the experiment that impact refining on virgin chemical pulp kept the fiber length and increased bonding properties greatly. However, in the recycled fibers from the chemical pulp, fiber length and bonding properties were decreased. In OCC, which seems to contain fractions of semi-chemical pulp and mechanical pulp (GP), and which is recycled pulp from corrugated boxes, fiber length and bonding properties were decreased disastrously. We believe recycled cellulosic fibers (recycled chemical pulp and OCC in this case), which went through hornification, were less resistant to the mechanical impact than virgin chemical pulp. For virgin chemical pulp, impact refining allowed no significant fiber length shortening, high WRV, and high mechanical strength.

• 한국전기전자재료학회논문지
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• 제16권8호
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• pp.700-704
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• 2003

This paper describes on characteristics of 2" 3C-SiC wafer bonding using PECVD (plasma enhanced chemical vapor deposition) oxide and HF (hydrofluoride acid) for SiCOI (SiC-on-Insulator) structures and MEMS (micro-electro-mechanical system) applications. In this work, insulator layers were formed on a heteroepitaxial 3C-SiC film grown on a Si (001) wafer by thermal wet oxidation and PECVD process, successively. The pre-bonding of two polished PECVD oxide layers made the surface activation in HF and bonded under applied pressure. The bonding characteristics were evaluated by the effect of HF concentration used in the surface treatment on the roughness of the oxide and pre-bonding strength. Hydrophilic character of the oxidized 3C-SiC film surface was investigated by ATR-FTIR (attenuated total reflection Fourier transformed infrared spectroscopy). The root-mean-square suface roughness of the oxidized SiC layers was measured by AFM (atomic force microscope). The strength of the bond was measured by tensile strength meter. The bonded interface was also analyzed by IR camera and SEM (scanning electron microscope), and there are no bubbles or cavities in the bonding interface. The bonding strength initially increases with increasing HF concentration and reaches the maximum value at 2.0 ％ and then decreases. These results indicate that the 3C-SiC wafer direct bonding technique will offers significant advantages in the harsh MEMS applications.ions.

• 한국분말재료학회지
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• 제17권2호
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• pp.113-122
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• 2010

Two kinds of oxide-dispersion-strengthened (ODS) 316L stainless steel were manufactured using a wet mixing process(wet) and a mechanical alloying method (MA). An MA 316L ODS was prepared by a mixing of metal powder and a mechanical alloying process. A wet 316L ODS was manufactured by a wet mixing with 316L stainless steel powder. A solution of yttrium nitrate was dried after being in the wet 316L ODS alloy. The results showed that carbon and oxygen were effectively reduced during the degassing process before the hydroisostatic process (HIP) in both alloys. It appeared that the effect of HIP treatment on increase in impact energy was pronounced in the MA 316L ODS alloy. The MA 316L ODS alloy showed a higher yield strength and a smaller elongation, when compared to the wet 316L ODS alloy. This seemed to be attributed to the enhancement of bonding between oxide and matrix particles from HIP and to the presence of a finer oxide of about 20 nm from the MA process in the MA 316L ODS alloy.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1996년도 제10회 학술발표회 논문개요집
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• pp.23-25
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• 1996

• 접착 및 계면
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• 제17권3호
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• pp.104-109
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• 2016

AC 코로나와 DC 코로나 처리 효과들을 비교하기 위해 선행연구의 DC 코로나 처리 조건들과 같이 폴리에스테르 직물들을 전류세기 5, 10, 15 A로, 공급속도 5, 10, 15 m/min로 AC 코로나 처리하였다. 이들의 표면변화를 주사전자현미경(SEM)과 X-ray 광전자분석기(XPS)로 확인하였고, 또한 물리적 성질의 변화를 건조 시와 습윤 시의 접착강도를 통하여 측정하였다. 대기압에서 AC 코로나 방전처리에 의해 폴리에스테르 직물의 표면변화는 DC 코로나 방전과 유사한 경향을 보였다. 일반적으로 AC, DC 코로나 처리 양쪽에서 건조 시의 접착강도는 전류세기와 공급속도가 증가할수록 증가하였으나, 습윤 시의 접착강도는 전류세기가 증가할수록 공급속도가 감소할수록 증가하였다. 전류가 20 A일 때 DC 코로나 방전에서는 탄화가 발생하였으나 AC 코로나에서는 탄화가 발생하지 않았다.

• Restorative Dentistry and Endodontics
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• 제24권4호
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• pp.570-577
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• 1999

치질에 대한 접착수복은 건전한 치질을 보존하면서 유지력을 증가시킬 뿐 아니라 치질과 수복물 계면에서의 미세누출을 방지할 수 있다는 측면에서 임상에서 그 사용빈도가 높아지고 있다. 그러나 복합레진충전후 중합과정에서의 수축현상이 여전히 해결되지 않는 문제로 남아 있으며 이로 인한 변연누출은 술후 지각과민, 변연변색이나 이차우식과 아울러 치수병변의 유발인자로 작용할 수 있다. 치질과 레진수복물간의 접착강도를 강화시킴으로써 변연부위의 누출현상을 극복할 수 있다는 인식 하에 많은 종류의 상아질 접착제에 대한 접착강도 검사와 미세누출 검사가 행해졌으나 접착강도와 변연누출간의 관계에 대한 직접적인 연구는 미흡한 상태이다. 본 연구에서는 우치를 이용한 동일시편에서 접착강도와 미세누출의 정도를 측정 후 상호관계를 알아보고자 하였다. 소의 하악 전치를 이용하여 법랑질 또는 상아질 시편을 각 군마다 30개씩 준비하였다. 32% 인산으로 15초 처리 및 20초 수세 후 치질처리 방법에 따라 법랑질/완전 건조시킨 군, 법랑질/습윤상태의 군, 상아질/완전 건조시킨 군, 상아질/습윤상태의 군으로 나누었다. 각 군의 시편을 One-Step$^{TM}$ adhesive를 적용 후 Charisma 복합레진으로 충전하였다. 그 후 2% methylene blue에 1주일 간 침잠시킨 후 24시간 흐르는 물에 수세한 뒤 인장접착 강도를 측정하였다. 인장 접착 강도 측정 후 컴퓨터 프로그램 상에서 색소의 침투 면적을 계산하였으며 그 결과는 다음과 같이 나타났다. 1. 법랑질 및 상아질 군 공히, 접착강도와 미세누출을 비교시 유의한 음의 상관관계를 나타내어 접착강도가 높을수록 미세변연누출은 적게 나타내는 경향을 나타내었다 (r=-0.50, p<0.05). 2 법랑질 군 및 상아질 군 공히, 습윤상태의 시편이 완전히 건조된 시편에 비해 높은 집착강도를 나타내었다 (p<0.05). 3. 상아질에서는 습윤상태의 군이 건조시킨 군 사이에 유의하게 적은 미세변연 누출을 나타낸 반면(p<0.05), 법랑질에서는 습윤상태의 군과 건조시킨 군 사이에 미세변연 누출에 있어 유의한 차이가 나타나지 않았다 (p>0.05).

• 한국재료학회지
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• 제19권11호
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• pp.625-630
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• 2009

Embedding of active devices in a printed circuit board has increasingly been adopted as a future electronic technology due to its promotion of high density, high speed and high performance. One responsible technology is to embedded active device into a dielectric substrate with a build-up process, for example a chipin-substrate (CiS) structure. In this study, desmear treatment was performed before Cu metallization on an FR-4 surface in order to improve interfacial adhesion between electroless-plated Cu and FR-4 substrate in Cu via structures in CiS systems. Surface analyses using atomic force microscopy and x-ray photoemission spectroscopy were systematically performed to understand the fundamental adhesion mechanism; results were correlated with peel strength measured by a 90o peel test. Interfacial bonding mechanism between electrolessplated Cu and FR-4 substrate seems to be dominated by a chemical bonding effect resulting from the selective activation of chemical bonding between carbon and oxygen through a rearrangement of C-C bonding rather than from a mechanical interlocking effect. In fact, desmear wet treatment could result in extensive degradation of FR-4 cohesive strength when compared to dry surface-treated Cu/FR-4 structures.