• 대한치과기공학회지
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• 제34권2호
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• pp.95-103
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• 2012

Purpose: Fracture strength of all-ceramic 3-unit fixed partial dentures manufactured by CAD/CAM and copy-milling systems were evaluated. Methods: Zirconia cores were made by milling the pre-sintered zirconia block by CAD/CAM or copy milling method followed by subsequent sintering. By building-up the corresponding porcelains on the core, all-ceramic bridges were fabricated, and those were evaluated in comparison with PFM fixed partial denture. Results: During the flexural test of the 3-unit PFM bridge, the porcelain started to chip or break at 507.28(${\pm}62.82$)kgf and the metal framework did not break until the maximum load level of 800kgf which was set in the testing instrument of this study. However, among all-ceramic restoration test groups, Everest(EV) group showed a peeling off or breakage of the porcelain from 365.64(${\pm}64.96$)kgf and the core was broken at 491.77(${\pm}55.62$)kgf. Those values of Zirkonzahn(ZR) were 431.03(${\pm}58.47$)kgf and 602.74(${\pm}48.44$)kgf, respectively. The break strength of the porcelain of PFM(PM) group was significantly higher than that of EV (p<0.05) group and there was no significant difference when comparing to that of ZR (p>0.05). ZR group showed higher break strength than that of EV group however there was no significant difference (p>0.05). The break strength of cores were in the increasing order of EV < ZR < PM (p<0.05). Conclusion: We could find that even though the PM group fractured at much higher value than all-ceramic cores, the breakage values of the porcelain of PM group with crack formation or delamination, which will be regarded as clinical failure, was significantly higher than that of EV group and not significantly higher than that of ZR group at p-values of 0.05. The break strength of ZR group was higher than that of EV group at an insignificant level(p>0.05).

• 한국재난정보학회 논문집
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• 제12권1호
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• pp.54-61
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• 2016

구조물에 복합재료를 사용한 보강과 복구에 대한 사용이 증가하고 있는 상황에서 갑작스러운 강도저하로 발생되는 재난을 피하기 위하여 임시 보강하고자 탄소섬유 판을 이용하여 기존금속재와 접합(접착방식)을 통한 강도증진효과를 연구하였다. 특히 실험을 통하여 강-탄소섬유보강재로 이루어진 복합 재 거동을 파악하였으며 여기에 적절한 시험을 위한 새로운 형태의 시험편을 제작하였다. 접합재로 레진을 접착하는 부착 면을 달리하여 거동을 비교하기 위하여 표면처리가 다른 시험편을 각각 고려하여 시험한 결과 강성보강효과는 물론 일체거동의 특성이 잘 나타남을 알 수 있었다.

• 한국재료학회지
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• 제18권9호
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• pp.486-491
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• 2008

The effect of annealing treatment conditions on the interfacial adhesion energy between electrolessplated Ni film and polyimide substrate was evaluated using a $180^{\circ}$ peel test. Measured peel strength values are $26.9{\pm}0.8,\;22.4{\pm}0.8,\;21.9{\pm}1.5,\;23.1{\pm}1.3,\;16.1{\pm}2.0\;and\;14.3{\pm}1.3g/mm$ for annealing treatment times during 0, 1, 3, 5, 10, and 20 hours, respectively, at $200^{\circ}C$ in ambient environment. XPS and AES analysis results on peeled surfaces clearly reveal that the peeling occurs cohesively inside polyimide. This implies a degradation of polyimide structure due to oxygen diffusion through interface between Ni and polyimide, which is also closely related to the decrease in the interfacial adhesion energy due to thermal treatment in ambient conditions.

• Structural Engineering and Mechanics
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• 제64권1호
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• pp.135-143
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• 2017

To upgrade shear performance of reinforced concrete (RC) beams, and particularly of the segments under negative moment within continuous T-section beams, a series of original schemes has been proposed using carbon fibre-reinforced polymer (CFRP) U-shaped strips for shear-strengthening. The current work focuses on one of them, in which CFRP U-strips are wound around steel bars against the top of the flange of a T-beam and then spliced on its bottom face in addition to being bonded onto its sides. The test results showed that the proposed scheme successfully provided reliable anchorage for U-strips and prevented premature onset of shear failure due to FRP debonding. The governing shear mode of failure changed from peeling of CFRP to its fracture or crushing of concrete. The strengthened specimens displayed an average increase of about 60% in shear capacity over the unstrengthened control one. The specimen with a relatively high ratio and uniform distribution of CFRP reinforcement had a maximum increase of nearly 75% in strength as well as significantly improved ductility. The formulas by various codes or guidelines exhibited different accuracy in estimating FRP contribution to shear resistance of the segments that are subjected to negative moment and strengthened with well-anchored FRP U-strips within continuous T-beams. Further investigation is necessary to find a suitable approach to predicting load-carrying capacity of continuous beams shear strengthened in this way.

• 대한환경공학회지
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• 제38권9호
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• pp.497-503
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• 2016

살균기능에 박리와 탈리기능 추가된 비유독물인 친환경살균제를 역삼투(RO)막 부착된 유기물 등 오염물질 제거를 위하여 현장 적용시 역삼투막 차압증가 도달시간을 기준 적용시 평균 93.0%의 개선효율을 보였다, 또한 친환경살균제를 사용한 역삼투막을 Autopsy한 결과, 무기 및 유기오염의 비율이 기존살균제에 비하여 친환경살균제를 사용한 역삼투막이 유기오염의 비율이 적은 것으로 조사됨에 따라 친환경살균제의 바이오필름 제거(분산, 박리) 및 살균력이 기존 약품보다 우수한 것으로 확인되었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.234-235
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• 2017

The bonding of the asphalt-based waterproof sheet is carried out in such a manner that the sheet and the sheet are adhered together and the lower adhesive layer of one sheet is adhered to the upper film layer of the other sheet, and the asphalt layer and the PE or HDPE film layer are bonded. When the joints are formed in the form of junctions between heterogeneous materials and exposed to the concrete joint movements and other deteriorating factors, the integrity of the joints can deteriorate and problems such as lifting and peeling off of the joints can occur. Therefore, this study was carried out to prevent unstable joint adhesion of the asphalt compound and film layer and to prevent defects in the adhesion between self - adhesive waterproof sheets. The self-adhesive waterproof sheet of this study can maximize bond stability by inducing bond between asphalt compounds during sheet-to-sheet bonding, thereby improving bonding strength.

• KIEAE Journal
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• 제5권3호
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• pp.49-56
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• 2005

Recently the Volatile Organic Compound, HCHO, a harmful object spout from the construction materials is made an issue of social problem. Also the appearance of the building where the confidentiality is high was interior air pollution and it was brought about a huge problem. The government research facility and a relation industry sector conducts a many effort to improves like this actual condition. The Diverse ability building material which contains the natural material of the jade, the charcoal and the hwangto instead of the finish material which contains the harmful chemical material, is becoming development and utility. Hereupon the study have carried out research on hwangto plaster that was composed of hwangto and rice straw. The result of test that is deduced by basic proportion is properly appeared with suitable ratio of the hwangto and the sand to 4:6~5:5 by the compressive strength and crack control, workability. The result of test, that adds the rice straw to basic blending for a crack control, appeared with the fact that it is most suitable 3%to add the rice straw that has a length of 0.5cm~2cm. The result of test that plaster over the large size to compare a cement plaster with a hwangto plaster show a similar efficiency by workability. Also it controlled the crack and peeling off actual condition which is discovered from the hwangto plaster of existing perfectly.

• 한국주조공학회지
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• 제19권5호
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• pp.410-418
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• 1999

To overcome the undesirable deformation, peeling off and geometrical restrictions which were mainly caused by differences in thermal expansion coefficients during the cladding of aluminum strip and stainless strip, new processing method based on vacuum die casting is designed and implemented in fabricating Fe-17wt%Cr steel (stainless steel). To increase cast-bonding ability, the surface of Fe-17wt%Cr steel is electrochemical etched to have optimum pit size (above 0.2 mm) and pit density (above 30%). The implementation of vacuum die casting by using surface treated stainless steel (Fe-17wt%Cr Steel) produces good trial products having acceptable cast-bonding ability. The enabling conditions for cast-bonding are pouring temperature $690^{\circ}C$, filling speed 30 m/sec and casting pressure $800\;kg/cm^2$. The microscopic observation of cast-bonded Al/Fe-17wt%Cr steel does not show any evidence of intermetallic compounds. The bonding strength of trial products is $150-400\;kg/cm^2$ and this is stronger than conventionally cladded metal having $30-70\;kg/cm^2$.

• 한국구조물진단유지관리공학회 논문집
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• 제2권2호
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• pp.202-208
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• 1998

To investigae the effect of anchorage type of carbon fiber sheet (CFS) on flexural behavior of RC beams, the loading test of RC beams reinforced with CFS was conducted in variable of anchorage Type such as bolting anchorage and U type anchorage using CFS. This study can be summarized as follows ; It is confirmed experimentally that the bolting anchorage and U type anchorage with CFS is very effective to delay the bond failure and prevent the peeling of CFS. Also, the anchorage type applied with this study is very effective to improve the ductility compared with the improving of maximum flexural strength of RC beams. It is believed that the anchorage type used this study must secure the ductile capacity of above 3 for the flexural strengthening of RC beams. In the future, it is required to obtain the data about anchorage type of CFS for utilization of field work as well as investigate the ductile capacity of conventional study of anchorage type

• Corrosion Science and Technology
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• 제22권4호
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• pp.232-241
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• 2023

The mechanical properties of the hydrogen valve responsible for supplying and blocking hydrogen gas in a hydrogen fuel cell electric vehicle (FCEV) were researched. Mechanical properties by hydrogen embrittlement were investigated by coating chromium nitride (CrN) and titanium nitride (TiN) on aluminum alloy by arc ion plating method. The coating layer was deposited to a thickness of about 2 ㎛, and a slow strain rate test (SSRT) was conducted after hydrogen embrittlement to determine the hydrogen embrittlement resistance of the CrN and TiN coating layers. The CrN-coated specimen presented little decrease in mechanical properties until 12 hours of hydrogen charging due to its excellent resistance to hydrogen permeation. However, both the CrN and TiN-coated specimens exhibited deterioration in mechanical properties due to the peeling of the coating layer after 24 hours of hydrogen charging. The specimens coated at 350 ℃ presented a significant decrease in ultimate tensile strength due to abnormal grain growth.