• Restorative Dentistry and Endodontics
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• 제25권4호
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• pp.575-586
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• 2000

In this study, adaptation of compomer to saliva contaminated dentin was evaluated with scanning electron microscope(SEM) and confocal laser scanning microscope(CLSM). For the SEM study, the occulusal surfaces of thirty two molar teeth were grounded to exposure dentin surfaces. The specimen were randomly assigned to control and three experimental groups with four samples in each group. In control group, Dyract and F-2000 compomer were bonded on the specimens according to the manufactures direction. Experimental groups were subdivided into three groups. They were contaminated with saliva on dentin surfaces ; Experimental group 1 : Saliva was dried with compressed air. Experimental group 2 : Saliva was rinsed with air-water spray and dried. Experimental group 3 : After polymerization of an adhesive, they were contaminated with saliva, and then saliva was rinsed with air-water spray and dried. Dyract and F-2000 compomer were bonded on saliva-treated dentin surfaces. The interfaces between dentin and compomer were observed with SEM. For the CLSM study, Class V cavities were prepared in buccal and ligual surfacess of thirty two molars. The specimens were divided into control and experimental groups. Class V cavities in experimental group were contaminated with saliva and those surfaces in each experimental groups received the same treatments as for the SEM study. Cavities were applied Prime & Bond 2.1 and F-2000 compomer primer/adhesive that were mixed with fluorescein, and then were filled with Dyract and F-2000 compomer. Specimens were embedded in transparent acrylic resin and sectioned buccolingual1y with diamond wheel saw, and then mounted on cover slide for CLSM study. The interface between cavity and compomer was observed by fluoresence imaging with a CLSM. The results were as follows : 1. In SEM exammination of Dyract group, control group, experimental group 2, 3 showed close adaptation to dentin and hybrid layer of $3{\sim}4{\mu}m$ diameter. Interfacial gap between compomer and dentin in experimental group 1 was wider than in control group. 2. In SEM examination of F-2000 group, adaptation to dentin of control group was closer than Dytact control group, but hybrid-like layer was not observed. Interfacial gap between compomer and dentin in experimental group 1 was wider than in Dyract experimental group 1. 3. In dissolution specimens of Dyract and F-2000 group, resin tags penetrated through dentinal tubules in control group and experimental group 1 and 3, but the penetration of resin tag was irregular and partial in experimental group 1. 4. In CLSM exammination of Dyract and F-2000 group, adhesive patterns of control and experimental groups showed same as in SEM. This result suggests the treatment methods, rinsing & drying, repeating all adhesive procedures, will produce good effect on adaptation of compomer to dentin if the dentin surface or polymerized adhesive is contaminated by saliva.

• 콘크리트학회논문집
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• 제22권5호
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• pp.727-736
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• 2010

본 논문은 인장에서의 연성능력을 유지하면서도 구조물 적용시에 지속가능성을 확보할 수 있는, 지속가능한 SHCCs를 제조하기 위한 기초자료를 제공하고자 한다. 본 연구의 목적은 자원순환형 재료가 압축, 휨, 직접인장거동 등 SHCCs의 역학적 특성에 미치는 영향을 평가함과 동시에, 구조물의 개발 및 해석시 구성모델에 대한 기초자료를 제공하는 것이다. 규사, 시멘트, PVA 섬유의 치환재로써 순환잔골재, 플라이애시, PET 섬유가 각각 SHCCs 배합에 일부 치환되었다. 실험결과, 플라이애시는 PVA 섬유와 시멘트 매트릭스 간 화학적 부착력을 증가시켜 SHCCs의 휨 및 직접인 장성능을 증가시킬 수 있는 것으로 나타났다. 그러나 PET 섬유가 치환된 SHCCs는 압축에서는 기준시험체인 PVA2.0과 유사하였으나, 섬유 자체의 낮은 기계적 특성으로 인해 휨 및 직접인장성능에서는 매우 낮게 나타났다. 순환골재의 경우 기존 규사보다 큰 골재치수로 인해 SHCCs의 탄성계수를 증가시키는 것으로 나타났다. SHCCs의 성능을 유지하기 위해 설정된 목표치를 근거로 할 때, 플라이애시는 20% 이하, 순환잔골재는 50% 이하로 치환하는 것이 지속가능한 SHCCs 제조에 바람직할 것으로 판단되었다.

• 한국도로학회논문집
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• 제5권2호
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• pp.15-24
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• 2003

방수시스템(WPS)의 성능은 재료 인자들의 복잡한 상호작용, 설계상세, 그리고 시공의 질에 따라 영향을 받고, 주로 인장접착강도(TAS)로 측정되는 교면과의 접착성에 의해 결정되는 것으로 알려져 있다. 따라서 본 연구는 현재 국내에 유통되고 있는 교면방수재 8종의 WPS의 성능을 아스팔트 포장층 혼합물의 종류, 시공시 혼합물의 온도, 포장층의 두께, 반복주행시험에 따른 접착특성을 중심으로 인장접착특성을 비교하였다. 또한 TAS 시험 후 계면에서의 탈리상태를 조사하였다. WPS에 대한 TAS 시험결과 SMA 혼합물이 밀입도 혼합물 보다 TAS가 크게 나타나 아스팔트 혼합물 종류에 따라서 차이가 났다. 시트식 방수재는 아스팔트 혼합물의 종류에 상관없이 시공온도가 높은 것이 접착력이 더 크게 나타났으나 도막식에서는 방수재 계열별로 다소 차이가 있고 시트식과 같지 않은 것으로 나타났다. 포장층 두께에 따른 영향은 방수재 종류에 상관없이 대동소이한 것으로 나타났다. 반복주행시험에 따라서 시트식에서의 접착력은 하중 재하지점>하중재하 않은 곳>하중 재하지점 옆 부근의 순서로 나타났고, 도막식에서는 방수재 종류에 따라 다르게 나타났다. 또한 방수재의 종류 및 특성에 따라 방수시스템 계면에서의 탈리상태가 다르다는 것을 알 수 있었다.

• 한국도로학회논문집
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• 제15권4호
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• pp.85-94
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• 2013

PURPOSES: The performance of tack coat, commonly used for layer interface bonding, is affected by application rate and curing time. In this study, bonding strength tests were performed according to the application rate and curing time of asphalt emulsion. Based on finding from this study, optimum application rates and curing times are proposed. METHODS: In order to investigate bonding characteristic of asphalt emulsion, tests were performed on both asphalt concrete pavement and portland concrete pavement. Also, asphalt emulsions were tested at the application rate of 0, 0.2, 0.4, 0.6, and $0.8{\ell}/m^2$ and at the curing time of 0, 0.5, 1, 2, and 24 hours. Pull-off test and shear bonding strength test, which commonly used for bonding strength measurement of asphalt emulsion, were adopted for this study. To assess field performance under different testing condition, asphalt emulsions were applied to in-service pavement. Throughout coefficient of determination analysis between material index properties from asphalt emulsion and mechanical response from bonding strength tests, performance correlativity was analyzed. RESULTS: Test results show that optimum application rate for asphalt overlay on asphalt concrete pavement (AOA) and asphalt overlay on concrete pavement (AOC) was $0.4{\sim}0.5{\ell}/m^2$ and $0.3{\sim}0.5{\ell}/m^2$, respectively. According to the curing time increment, tensile strength and shear strength of AOC were increased to 22~44% and 20~39%, respectively. AOA case also show strength increment in tensile strength (42%) and shear strength (9%). We tested the applicability of tack coat materials at the field sites, and our findings demonstrated that the bonding (for D and E) and rapid curing (for B, C, and D, E) performances were superior than others. Among material index properties, there was a high correlation between penetration ratio and bonding strength test result. CONCLUSIONS : Result show that interlayer bonding strength was affected by asphalt emulsion type, application rate and curing time. AOC required slightly higher application ($0.1{\ell}/m^2$) than AOA. Both AOA and AOC cases show higher strength at longer curing time. Up to 2hours of curing, rapid strength increments were observed, but strength increment ratio was decreased after 2hours of curing. From the observed correlation between penetration ratio and bonding strength, it is expected that penetration ratio can be used as one of important factors affecting bonding strength analysis.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.102-102
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• 2018

Electronic industry had required the finer size and the higher performance of the device. Therefore, 3-D die stacking technology such as TSV (through silicon via) and micro-bump had been used. Moreover, by the development of the 3-D die stacking technology, 3-D structure such as chip to chip (c2c) and chip to wafer (c2w) had become practicable. These technologies led to the appearance of HBM (high bandwidth memory). HBM was type of the memory, which is composed of several stacked layers of the memory chips. Each memory chips were connected by TSV and micro-bump. Thus, HBM had lower RC delay and higher performance of data processing than the conventional memory. Moreover, due to the development of the IT industry such as, AI (artificial intelligence), IOT (internet of things), and VR (virtual reality), the lower pitch size and the higher density were required to micro-electronics. Particularly, to obtain the fine pitch, some of the method such as copper pillar, nickel diffusion barrier, and tin-silver or tin-silver-copper based bump had been utillized. TCB (thermal compression bonding) and reflow process (thermal aging) were conventional method to bond between tin-silver or tin-silver-copper caps in the temperature range of 200 to 300 degrees. However, because of tin overflow which caused by higher operating temperature than melting point of Tin ($232^{\circ}C$), there would be the danger of bump bridge failure in fine-pitch bonding. Furthermore, regulating the phase of IMC (intermetallic compound) which was located between nickel diffusion barrier and bump, had a lot of problems. For example, an excess of kirkendall void which provides site of brittle fracture occurs at IMC layer after reflow process. The essential solution to reduce the difficulty of bump bonding process is copper to copper direct bonding below $300^{\circ}C$. In this study, in order to improve the problem of bump bonding process, copper to copper direct bonding was performed below $300^{\circ}C$. The driving force of bonding was the self-annealing properties of electrodeposited Cu with high defect density. The self-annealing property originated in high defect density and non-equilibrium grain boundaries at the triple junction. The electrodeposited Cu at high current density and low bath temperature was fabricated by electroplating on copper deposited silicon wafer. The copper-copper bonding experiments was conducted using thermal pressing machine. The condition of investigation such as thermal parameter and pressure parameter were varied to acquire proper bonded specimens. The bonded interface was characterized by SEM (scanning electron microscope) and OM (optical microscope). The density of grain boundary and defects were examined by TEM (transmission electron microscopy).

• 폴리머
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• 제39권2호
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• pp.329-337
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• 2015

본 연구에서는 다중벽 탄소나노튜브(MWCNTs)를 질산과 황산의 혼산으로 산화시켜 표면에 카르복시기를 도입 후, $SOCl_2$와 1,4-butanediol을 사용하여 MWCNT-OH를 제조하였다. 제조된 MWCNT-OH는 3-methacryloxypropyltrimethoxylsilane(MPTMS)와 실란화 반응으로 methacrylate기가 도입된 MWCNT-MPTMS를 제조하였다. MWCNT-MPTMS와 methyl methacrylate(MMA)를 사용하여 유화중합법으로 MWCNT-MPTMS/PMMA 복합 입자를 제조하였다. 음이온 계면 활성제인 sodium dodecylbenzene sulfonate(SDBS)를 사용하여 유화중합한 MWCNT-MPTMS/PMMA는 균일한 입도, 좁은 입도분포 및 계면에서의 화학결합으로 인하여 $T_g$가 순수 MWCNT를 사용하여 중합한 시료보다 $3.4^{\circ}C$ 높아짐을 확인하였다.

• 콘크리트학회논문집
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• 제28권6호
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• pp.637-646
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• 2016

이 연구에서는 강섬유 보강 초고성능 콘크리트(Ultra-high performance fiber reinforced concrete, 이하 UHPFRC)로 보강된 콘크리트 계면에서의 전단강도 평가를 위한 경사전단실험을 수행하였다. 실험변수는 면처리 유무와 콘크리트 강도, 그리고 UHPFRC의 강섬유 혼입률이다. 콘크리트의 계면은 숏블라스팅으로 면처리되었다. 실험결과, 숏블라스팅으로 면처리된 실험체의 계면 전단강도는 매끄러운 표면을 가진 실험체의 부착강도에 비해 매우 크게 나타났으며, 거친면을 만들기 위한 숏블라스팅 방법은 매우 효과적인 방법인 것으로 나타났다. 숏블라스팅으로 표면처리를 할 경우, 전단마찰 철근이 없더라도 콘크리트 계면에서 저항하는 전단강도는 현행 기준에서 제시하고 전단강도 상한값을 초과하는 것으로 나타났다. 기존의 콘크리트와 UHPFRC 사이의 전단마찰 설계는 전단마찰 철근의 유무와 상관없이 현행 콘크리트 구조기준을 사용해도 무방할 것으로 판단된다. 다만, 면처리를 하지 않은 경우에는 적절한 전단 보강재가 추가 설치하여야 할 것이다.

• Restorative Dentistry and Endodontics
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• 제19권1호
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• pp.148-158
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• 1994

The purpose of this study was to compare the adaptation to tooth structure of light - cured glass ionomer cement with that of self -cured glass ionomer cement. In this study, class V cavities were prepared on the buccal surfaces of 10 extracted human premolar teeth, and teeth were randomly assigned 2 groups of 5 teeth each. The cavities of self-curing glass ionomer cement group were restored with the Fuji n. and the cavities of lightcuring glass ionomer cement group were restored with the Fuji II LC. The surfaces of glass ionomer cements were applied with All-Bond 2 adhesive, and cured with visible light. The restored teeth were stored in 100% relative humidity at $37^{\circ}C$ for 24 hours. And then. the roots of the teeth were removed with the tapered fissure bur and the remaining crowns were sectioned occlusogingivally through the center of glass ionomer restorations. Adaptation at tooth-restoration interface was assessed occlusally. axially, and gingivally by scanning electron microscope. The results were as follows : 1. On the occlusal margin, the group of self - curing glass ionomer cement showed closer adaptation to both enamel and dentin than the group of light-curing glass ionomer cement showing 5/lm gap between cement and tooth structure. 2. On the axial wall. the group of light-curing glass ionomer cement showing 5-$7{\mu}m$ gap between cement and dentin showed closer adaptation to dentin than the group of self -curing glass ionomer cement showing 10-$15{\mu}m$ gap between cement and dentin. 3. On the gingival margin, the group of light-curing glass ionomer cement showing 2-$5{\mu}m$ gap between cement and dentin(X 1200) showed closer adaptation to dentin than the group of self-curing glass ionomer cement showing 20pm gap between cement and dentin(X 600). 4. The group of self -curing glass ionomer cement showed closer adaptation on the occlusal margin than on the gingival margin, and the group of light-curing glass ionomer cement showed similar adaptation on both occlusal and gingival margins.

• 한국주조공학회지
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• 제41권6호
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• pp.535-542
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• 2021

본 연구에서는 주철-알루미늄 이종재료의 계면결합강도를 향상시키기 위하여 탈흑연 열처리를 통해 주철 표면에서 일정 깊이까지의 흑연을 제거하였다. 열처리 시간이 증가함에 따라 흑연이 제거되는 깊이는 증가하였으며, 열처리 시간과 깊이 사이에 선형 관계가 나타났다. 일정 깊이의 흑연이 제거된 주철에 알루미늄을 다이캐스팅 공법으로 주조접합하여 주철에서 흑연이 제거된 공간을 알루미늄으로 채운 후, 계면 반응 및 알루미늄 침투 깊이를 조사하고 계면접합강도를 평가하였다. 다이캐스팅 공법을 통한 알루미늄은 탈흑연 열처리된 주철 표면에서 일정한 깊이까지 채워지는 것으로 확인되었으며, 주철-알루미늄 계면에 금속간화합물이 생성되지는 않은 것으로 확인되었다. 계면접합강도는 열처리 시간과는 큰 관계없이 90MPa 수준의 접합강도를 나타내었으며 이는 탈흑연 열처리를 하지 않은 소재의 접합강도 12MPa에 비해 매우 높은 강도이며, 주철의 탈흑연 영역에서 고압 다이캐스팅 공정에 의해 침투된 알루미늄 용탕이 응고되면서 언더컷 구조의 기계적 결합에 의한 것으로 생각된다.

• Interdisciplinary Bio Central
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• 제1권1호
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• pp.3.1-3.6
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• 2009

Introduction: GTPases known as translation factor play a vital role as ribosomal subunit assembly chaperone. The bacterial Obg proteins ($Spo{\underline{0B}}$-associated ${\underline{G}}TP$-binding protein) belong to the subfamily of P-loop GTPase proteins and now it is considered as one of the new target for antibacterial drug. The majority of bacterial Obgs have been commonly found to be associated with ribosome, implying that these proteins may play a fundamental role in ribosome assembly or maturation. In addition, one of the experimental evidences suggested that Bacillus subtilis Obg (BsObg) protein binds to the L13 ribosomal protein (BsL13) which is known to be one of the early assembly proteins of the 50S ribosomal subunit in Escherichia coli. In order to investigate binding mode between the BsObg and the BsL13, protein-protein docking simulation was carried out after generating 3D structure of the BsL13 structure using homology modeling method. Materials and Methods: Homology model structure of BsL13 was generated using the EcL13 crystal structure as a template. Protein-protein docking of BsObg protein with ribosomal protein BsL13 was performed by DOT, a macro-molecular docking software, in order to predict a reasonable binding mode. The solvated energy minimization calculation of the docked conformation was carried out to refine the structure. Results and Discussion: The possible binding conformation of BsL13 along with activated Obg fold in BsObg was predicted by computational docking study. The final structure is obtained from the solvated energy minimization. From the analysis, three important H-bond interactions between the Obg fold and the L13 were detected: Obg:Tyr27-L13:Glu32, Obg:Asn76-L13:Glu139, and Obg:Ala136-L13:Glu142. The interaction between the BsObg and BsL13 structures were also analyzed by electrostatic potential calculations to examine the interface surfaces. From the results, the key residues for hydrogen bonding and hydrophobic interaction between the two proteins were predicted. Conclusion and Prospects: In this study, we have focused on the binding mode of the BsObg protein with the ribosomal BsL13 protein. The interaction between the activated Obg and target protein was investigated with protein-protein docking calculations. The binding pattern can be further used as a base for structure-based drug design to find a novel antibacterial drug.