• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.6
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• pp.77-86
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• 2007

The repair technique utilizing surface impregnant is widely used due to its simple construction procedures and economical benefit. Surface protection through this reparing technique cannot increase the bearing capacity of concrete members much but increase the durability performance and service life efficiently. In this study, fundamental tests such as water suction and permeation are performed for concrete specimens with several organic/inorgarnic impregnant and suitable impregnant is selected on the basis of the results. Finally, durability tests such as carbonation, freezing and thawing, and chloride attack are carried out for the concrete specimens with selected impregnant and it is experimentally verified that they have good resistance to deteriorations.

• Korean Journal of Crystallography
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• v.19 no.1
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• pp.7-13
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• 2008

고체 표면의 구조해석 방법에는 LEED(저에너지 전자선 회절법)나 RHEED(반사 고에너지 전자선 회절법) 등과 같이 표면의 2차원적 회절상을 해석하는 방법이 있고(역격자 공간의 해석), 또는 ISS(이온산란 분광법), RBS(러더포드 후방산란법) 등과 같이 표면 원자의 실공간에 대한 정보를 직접 얻는 방법이 있다. 실제로는 두 가지 종류의 분석법을 상호 보완적으로 조합하여 효율적인 구조해석을 수행한다. 본고에서는 직충돌 이온산란 분광법(ICISS: Impact Collision Ion Scattering Spectroscopy)에 대한 원리, 장치, 측정방법 등을 소개한 전고에 이어서 이를 이용한 반도체 표면구조 해석에 관하여 기술하고자 한다. 표면의 원자구조를 알아내기 위해서는 산란된 입자의 강도를 입사각도와 출사각도에 대하여 조사하여야 하는데, 이온이 원자와 충돌하여 산란될 때 원자의 후방으로 형성되는 shadow cone에 의하여 생성되는 집속 효과(focusing effect) 및 가리움 효과(blocking effect) 중에서 ICISS는 집속 효과만을 고려하여 해석하면 실공간에서의 원자구조를 해석할 수 있다. 본 고에서는 ICISS를 이용하여 금속 또는 절연체 물질이 반도체 표면 위에서 흡착 또는 성장될 때 초기의 계면 구조 해석, 금속/반도체 계면에서 시간에 따른 동적변화 해석, III-V족 반도체의 표면구조 해석, 반도체 기판 위에서 박막 성장 과정 해석 등에 관한 연구 사례를 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.3
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• pp.570-575
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• 2002

It is well-known that the bond strength between CFRP(Carbon Fiber Reinforced Plastic) and aluminum is significantly affected by the surface treatment of the CFRP and the aluminum. This study investigates the surface treatment of CFRP to improve the T-peel strength of CFRP/aluminum composites. The surface of %CFRP([0^0]_{14})$ was treated by the ion assisted reaction method under oxygen environment. T-peel strength tests were performed based on the procedure of ASTM D1876-95. The T-peel strength of surface-treated CFRP/aluminum composites was compared with that of untreated CFRP/aluminum composites. The results showed that the T-peel strength of surface-treated CFRP/aluminum composites was about 5.5 times higher than that of untreated CFRP/aluminum composites. SEM examination showed that the improvement of T-peel strength was attributed to the uniform spread and fracture of epoxy adhesive.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.116.2-116.2
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• 2017

DLC (Diamond like carbon) 박막을 전극 재료로 활용하기 위해서는 높은 전기 저항과 금속성 기판에 대한 낮은 접착력을 극복해야 한다. 본 연구에서는 PECVD에 의해 합성 된 DLC/Ti 전극의 아크 중간층, 질소 도핑, 증착 및 열처리 온도가 접착 강도와 전기적 및 전기 화학적 특성에 주는 영향을 체계적으로 조사 하였다. 그 결과, arc ion plating (AIP) 법에 의해 증착 된 Ti/TiC 중간층의 도입은 스크래치 테스트와 전기화학적 싸이클 테스트에서 향상된 접착 강도 및 수명을 가져온다는 것을 확인 하였다. 그리고 arc 중간층에서의 arc droplet은 DLC 박막의 표면적을 넓혀 전기 화학적 활성도를 높이는 긍정적인 역할을 하였다. 소량의 질소 도핑은 DLC 막의 비저항을 크게 낮춰주었고, 전기화학적 활성도를 증가시켰다. 증착 온도가 높을수록 DLC 막의 sp2/sp3 비율이 증가하였고, 이에 따라 비저항은 감소하였으며 전기 화학적 활성도는 증가하였다. 반면, 가장 높은 전기화학적 전위창은 $300^{\circ}C$ 에서 얻어졌으며 더 높은 온도에서 감소하였다. 열처리 온도를 높일수록 비저항의 감소 및 전기 화학적 활성도가 증가한 반면, 전기화학적 전위창은 지속적으로 감소하였고, 높은 열처리 온도에서는 DLC 전극의 수명이 줄어드는 것을 확인 하였다.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.1
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• pp.147-154
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• 2020

The exterior finishing of reinforced concrete buildings is one of the important factors to prevent durability and prevent natural environment or disaster such as temperature, snow, wind, rain from the outside as well as external design of buildings. Finishing methods can be divided into wet and dry methods. The wet method using paint is relatively easy to construct, but it requires repair and reinforcement every 1 to 5 years and requires a lot of LCC for maintenance. Finishing method using panel has good durability, but it is difficult to install and expensive. Therefore, in this paper, we evaluate the bond strength for the application of the metal spray method in order to overcome the problems of existing methods. Experimental results show that the sandblast + surface roughness agent(S-R(Y)) has a roughness of 41.16 ㎛ and the bond strength is about 3.19 MPa, which is the highest bond strength. In addition, the grinding + surface roughness agent(G-R(Y)) application showed roughness of about 36.59 ㎛ and secured the bond strength performance of 2.94 MPa.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.8-15
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• 2011

Purpose: This study evaluated the bonding strength of direct relining resin to Co-Cr denture base material according to surface treatment and immersion time. Materials and methods: In this study, Co-Cr alloy was used in hexagon shape. Each specimen was cut in flat surface, and sandblasted with $110\;{\mu}m$ $Al_2O_3$ for 1 minute. 54 specimens were divided into 3 groups; group A-control group, group B-applied with surface primer A, group C-applied with surface primer B. Self curing direct resin was used for this study. Each group was subdivided into another 3 groups according to the immersion time. After the wetting storage, shear bond strength of the specimens were measured with universal testing machine. The data were analyzed using two-way analysis of variance and Tukey post hoc method. Results: In experiment of sandblasting specimens, surface roughness of the alloy was the highest after 1 minute sandblasting. In experiment of testing shear bond strength, bonding strength was lowered on group B, C, A. There were significant differences between 3 groups. According to period, Bonding strength was the highest on 0 week storage group, and the weakest on 2 week storage group. But there were no significant differences between 3 periods. According to group and period, bonding strength of all group were lowered according to immersion time but there were no significant differences on group B and group C, but there was significant difference according to immersion time on group A. Conclusion: It is useful to sandblast and adopt metal primers when relining Co-Cr metal base dentures in chair-side.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.4
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• pp.383-388
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• 2012

The aim of this study was to compare the compressive strength and the surface microhardness of Beautifil flow (Shofu, Kyoto, Japan) with $Filtek^{TM}$ Z350, Z350XT (3M ESPE, USA). Fifteen specimens from each material were fabricated for testing. Compressive strength was measured by using a universal testing machine at a crosshead speed of 1 mm/min. Surface microhardness values were measured by using Vickers hardness tester under 4.9 N load and 10 seconds dwelling time. The compressive strength of Group 2 $Filtek^{TM}$ Z350XT shows the highest value as $218.7{\pm}18.4$ MPa and Group 1 $Filtek^{TM}$ Z350 was $205.5{\pm}27.1$ MPa. Group 3 Beautifil flow F00 was $176.5{\pm}30.3$ MPa, and Group 4 Beautifil flow F10 was $173.4{\pm}26.2$ MPa. The compressive strength of Group 2 is higher than Group 3 and 4 (p < 0.05). The surface microhardness of Group 2 $Filtek^{TM}$ Z350XT shows the highest value as $39.1{\pm}2.1$ and Group 4 Beautifil flow F10 was $27.9{\pm}1.8$. And Group 3 Beautifil flow F00 was $23.1{\pm}1.1$, Group 1 $Filtek^{TM}$ Z350 was $20.4{\pm}0.9$. There was a statistical significant difference in surface microhardness between all groups (p < 0.05). In conclusion, the compressive strength of giomer was below the level of flowable composite resin. However, the surface microhardness of giomer is comparable to that of flowable composite resin. Giomer would be the good alternative to composite resin, if there is improvement of the compressive strength of giomer.

• The korean journal of orthodontics
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• v.34 no.5 s.106
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• pp.439-447
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• 2004

The purpose of this study was to investigate the influence of water, saliva and blood contamination on the bonding strength of metal brackets with a self-etching primer/adhesive to enamel. Ninety-six extracted human teeth were divided into four groups. The brackets were bonded to enamel with a self- etching primer (3M/Unitek Dental Products. Monorovia California) according to one of four protocols. The teeth were bonded in a dry condition (group D) or in contamination with distilled water (group W), artificial saliva (group S). or fresh human blood (group B) Shear bond strengths were tested using an Instron Universal testing machine. After debonding. bracket and tooth surfaces were examined with a stereomicroscope. In each group, four samples were selected and examined with a Scanning electron microscope of the prepared enamel surface and resin-enamel interlace. The results obtained were summarized as follows: Shear bond Strength if group D $(15.22{\pm}2.86MPa)$ and W $(15.20{\pm}3.85 MPa)$ Were higher than in group B$(12.56{\pm}2.94MPa)$ (p<0.05). There were no statistical differences in the shear bond strengths between groups D. W and S (p>0.05). There was a tendency to have less residual adhesive remaining on the enamel surfaces of group B than group D. The SEW morphology of group D and W showed a more roughened etching pattern than group S and B. Water or saliva contamination on bending of orthodontic brackets with Transbond plus self etching primer had almost no influence on bond strength In this study, the blood contaminated group showed the lowest bond strength, but it was above the clinically acceptable bond strength (5.9-7.8 MPa, Reynold, 1975). The results of this study suggest that acceptable clinical bond strengths can be obtained in wet conditions when self-etching adhesives are used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.93-99
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• 2019

The purpose of this study was to investigate the bond strength between PEKK(Polyetherketoneketone) and Sinfony(3M ESPE, Seefeld, Germany) the dental composite resin by proposing the three representative surface treatment methods and evaluate to see if they affect the bond strength between two materials. A total of 30 PEKK($Pekkton^{(R)}$ Ivory, $Cendres+M{\acute{e}}taux$, Bienne, Switzerland) specimens were prepared, embedded in acrylic resin, polished(P 1200 grid) to surface, and each group was divided into 10 specimens. After then, by the surface treatment method, it classified into three groups(n=10) such as Air abrasion group(PN), applying Single Bond Universal(3M ESPE) after Air abrasion(PB), applying OPAQUE(3M ESPE) after Air abrasion(PO). Then, veneering was performed by using Sinfony(3M ESPE, Seefeld, Germany). All completed specimens were allowed to rest in a $37^{\circ}C$ water bath for 24 hours. Shear bond strength of each group was measured and fracture patterns were classified. Statistic analysis was performed with One-way ANOVA followed by post hoc Scheffe tast (p<.05). Statistical analysis was performed using the SPSSWIN 21.0 program. As a result of one-way ANOVA, the average value of PB group was $27.67{\pm}4,18MPa$ and it was shown as the highest bond strength, PN and PO were $20.43{\pm}1.70$ and $19.8{\pm}4.77MPa$ each, and these were relatively low(F=18.4, P<.001), and as the post-test the Scheffe test was conducted and verified (p<.05). After examining the scheffe test, it was showed significant differences as PB>PO, PB>PN(p<.001). Through this study, in order to enhance the bonding force between PEKK and the composite resin, perform the Air abrasion and surface treatment by using Single Bond Universal(3M ESPE) is recommended, and as coMPared with other studies. And it is assumed that the increase of the application time of the Air abrasion affects the increase of the shear bond strength. Thus, further research is required.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.229-238
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• 2002

This paper introduces the surface roughness parameter, Rs to the characterization of joint roughness and quantitatively illustrates the influence of joint roughness on the joint shear strength. A new peak shear strength criterion for rock joints using Rs is suggested. The results show that the surface roughness parameter, Rs can appropriately reflect the degree of roughness for the rock joint surfaces tested in this study A measuring interval of 2mm and profile length of 5cm can be used to characterize the joint roughness of the rock core size surfaces; however, the scale of fluctuation, $\delta_\alpha$ should be considered to extend the surface roughness parameter, Rs to the large-scale field rock joint surfaces. For the smooth joint roughness, sliding of the rock cores is the principal shear mechanism; however, the breakage of roughness from the rock cores is inferred for rougher joint roughness.