• 한국어정보학회:학술대회논문집
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• 2017.10a
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• pp.298-300
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• 2017

본 논문에서는 단순하지만 효과적인 단어 표현 방법인 Bags of Features에 대한 비교 실험을 수행한다. Bags of Features는 어휘집의 크기에 제한이 없으며, 문자 단위의 정보를 반영하고, 벡터화 과정에서 신경망 구조에 의존하지 않는 단어 표현 방법이다. 영어 품사 부착 실험을 사용하여 실험한 결과, one-hot 인코딩을 사용한 모델과 대비하여 학습 데이터에 존재하지 않는 단어의 경우 49.68%, 전체 부착 정확도는 0.96% 향상이 관찰되었다. 또한, Bags of Features를 사용한 모델은 기존의 영어 품사 부착 분야의 최첨단 모델들 중 학습 데이터 외의 추가적인 데이터를 활용하지 않는 모델들과 비견할 만한 성능을 보였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.112-121
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• 2013

FRP reinforced lightweight concrete structures can offer corrosion resistance and weight reduction effect simultaneously, so practical use of the structures may be expected afterwards. But to make concrete structures using lightweight concrete and FRP bar, that can resist external forces without internal slip of the FRP bar, it is very important to understand bond characteristic between lightweight concrete and FRP bar. During that time, a lot of studies for bond behaviors of FRP bar in normal concrete were conducted, but studies for bond behavior of FRP bar in lightweight concrete are very limited to date. So, bond characteristic between lightweight concrete and helically deformed GFRP bar was investigated in this study. Three main parameters were considered in experimental investigation: type of rebar, concrete type, and compressive strength of lightweight concrete. As an experimental result, it could be known that bond strength of helically deformed GFRP bar in lightweight concrete was 0.49 times bond strength of steel reinforcement in normal concrete.

• Journal of the Korea Concrete Institute
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• v.25 no.5
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• pp.547-554
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• 2013

This study was intended to estimate the bond strength of steel fiber in UHPFRC through pullout test. The pullout test was carried out with the double-sided pullout specimens with multiple fibers. First, the effect of fiber density on the bond strength was investigated, and the experimental result presented that the density range considered in this study was proved not to produce fiber-to-fiber interaction. The bond strength was estimated from several methods, which are based on the pullout load or energy at peak load, and the total energy absorbed until fibers are pulled out completely. the estimated bond strength obtained from the total energy was shown to be under the influence of the embedded length of fiber. the bond strengths obtained from peak load condition was 6.64 MPa in average, which had little difference compared to 6.46 MPa calculated by peak load only. Considering simplicity of test and analysis, it may be no matter to estimate the bond strength from peak load in pullout test.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.102-109
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• 2010

This paper investigates the bond behavior of reinforced concrete beams having high-strength transverse reinforcement. A total of four reinforced concrete beams were tested in this study to estimate the bond capacity of the proposed U-shape reinforcement. The proposed U-shape reinforcement not only has a simple structure to install, but also can increase the bond capacity of reinforced concrete beams by controling bond cracks. This study follow the test method proposed by Ichinose to obtain the bond stress and the bond slip of the specimens. The main test parameters were the yield strength, ratio, and reinforcing types of transverse reinforcements. It was found that the proposed U-shape reinforcement was able to effectively improve the bond performance of reinforced concrete beams with high-strength transverse reinforcement.

• Journal of the Korea Concrete Institute
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• v.28 no.5
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• pp.535-544
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• 2016

This paper aims at examining the effects of sustained load and elevated temperature on the time-dependent deformation of a carbon fiber reinforced polymer (CFRP) sheets bonded to concrete as well as the pull-off strength of single-lap shear specimens after the sustained loading period using digital images. Elevated temperature during the sustained loading period resulted in increased slip of the CFRP composites, whereas increased curing time of the polymer resin prior to the sustained loading period resulted in reduced slip. Pull-off tests conducted after sustained loading period showed that the presence of sustained load resulted in increased pull-off strength and interfacial fracture energy. This beneficial effect decreased with increased creep duration. Based on analysis of digital images, results on strain distributions and fracture surfaces indicated that stress relaxation of the epoxy occurred in the 30 mm closest to the loaded end of the CFRP composites during sustained loading, which increased the pull-off strength provided the failure locus remained mostly in the concrete. For longer sustained loading duration, the failure mode of concrete-CFRP bond region can change from a cohesive failure in the concrete to an interfacial failure along the concrete/epoxy interface, which diminished part of the strength increase due to the stress relaxation of the adhesive.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1153-1163
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• 2013

Bonded concrete overlay is a favorable maintenance method since the material properties are similar to existing concrete pavements. In addition, bonded concrete overlay has advantage of structural performance based on being bonded together, both for the overlay layer and the existing pavement which perform as one monolithic layer. Therefore, it is important to have a suitable bond strength criteria for long term performance of bonded concrete overlay. This study aimed to investigate the affecting of bond strength on various bond characteristics, and to compare the bond strength between direct tensile test and indirect tensile test due to various conditions such as overlay materials, compressive and flexure strength of existing pavement, and deterioration status of existing pavement. As a result of this study, bond strength occurred by both of direct and indirect tensile test due to monotonic load is highly correlated such as coefficient of determination of 0.75 and P-value of 0.002. However, bond strength by indirect tensile test was relatively higher than bond strength by direct tensile test. It was known that correlation between direct and indirect tensile test was possible to use the characteristics analysis of bond fatigue behavior based on bond strength due to cyclic load which can simulate real field behavior of bonded concrete overlay.

• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.40.1-40.1
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• 2010

초고성능 콘크리트(Ultra High Performance Concrete, UHPC)는 종래의 보통 콘크리트와 다른 새로운 재료로써 높은 강도와 향상된 연성을 그 특징으로 한다. 이러한 새로운 재료의 활용을 위하여 본 연구는 초고성능 콘크리트의 부착 성능을 평가하고자 하였다. 수정된 RILEM 방법을 사용하여 초고성능 콘크리트와 이형철근의 pull-out 실험을 수행하였으며 보통 콘크리트와 비교하여 5~10배에 달하는 부착강도를 확인하였다. 또한 항복강도 400MPa급 철근에 대하여 철근 직경 2배 이상의 부착 길이에서 철근의 파단 강도에 해당하는 부착 성능을 나타내었으며 400MPa급 철근과 700MPa급 고장력 철근의 실험 결과 비교로부터 초고성능 콘크리트에서 고장력 철근 활용의 효율성을 확인하였다.

• Journal of the Korean Society for Advanced Composite Structures
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• v.2 no.3
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• pp.36-41
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• 2011

This study proposes a experimental method to evaluate bonding strength of FRPs used for retrofitting concrete structures. Specimens are designed so that debonding failure of FRPs can be induced from reinforced concrete beams retrofitted with two layers of carbon and glass FRPs. And three-point loading tests are performed to see if debonding failure with proper debonding strength is observed from the specimens. The test results show that the tested beams are failed due to debonding of FRPs, therefore, the proposed test method is capable of evaluating debonding strength of FRPs using relatively small normal strength concrete beams.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.97-97
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• 2003

유용 수산생물인 전복, 소라, 성게 등 무척추동물의 종묘생산에 있어 부착 규조류는 수서 생태계의 일차 생산자로서 유생의 변태와 변태 후의 초기 먹이생물로 활용되고 있으며 최근에는 단일 부착규조류의 실내 배양을 통해 유용 수산생물 종묘의 대량 생산을 유도하고 있다. 부착규조류의 생물량 및 종 조성에 따라 이들 조식동물의 성장과 먹이 효율성에 커다란 영향을 끼친다. 이 연구는 종묘생산의 환경 조건과 동일한 현장에서 유수식 수조에 투명 플라스틱 부착파판(30$\times$40cm)을 설치하여 1997년 10월부터 1999년 4월까지 실내수조에 설치한 부착파판을 10일 간격으로 회수하여 부착된 규조류의 생물량과 환경적 특성을 조사하였다. 실험기간 동안 자연광을 55~75% 차단한 상태에서 실험을 진행하였고 수온과 염분은 각각 14.1$^{\circ}C$~28.6$^{\circ}C$와 32.5$\textperthousand$~35.3$\textperthousand$의 범위를 보였다. 실험기간 동안 부착규조류의 총 출현종수는 27종(17속 25종 2미동정종)으로 중심규조류(centric diatom)가 4종 그리고 우상규조류(pennate diatom)가 23종이었다. 현존량의 30% 이상을 점유하는 부착 규조류들은 Bacillaria paxillifera, Cocconeis scutellum, Diatoma hyalina, Navicula mollis, Nitzschia sp., Synedra tabulta 등 6종이 우점하였다. 부착규조류의 현존량은 2.5$\times$$10^3$~ 5.0$\times$$10^{5}$ cells $cm^{-2}$ 의 분포 범위로 1999년 4월에 가장 높고 1997년 10월에 가장 낮았다. Chlorophyll $\alpha$량 ($\mu\textrm{g}$ chl $\alpha$ $cm^{-2}$)은 0.02 ~ 1.72 $\mu\textrm{g}$ chi $\alpha$ $cm^{-2}$의 범위로써 부착규조류의 현존량과 유사한 분포 특성을 보였다. 유수식 실내수조에 부착된 부착규조류의 부착 형태, 우점종과 현존량은 배양 시기에 따라 종간 특이성을 보였다.다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.439-445
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• 2008

This paper suggests a modified bond reduction coefficient considering the average CFRP (Carbon Fiber Reinforced Polymer) strain concept for the unbonded prestressed CFRP plate strengthening system. The strengthened length and the pure bending length were seen to influence the variation of the strain of unbonded CFRP plate. Therefore, a new bond reduction coefficient considering such effect was suggested. Comparison with the experimental data revealed that the analytic results obtained by considering the proposed bond reduction coefficient were effective in estimating the strain of the unbonded CFRP plate in the CFRP plate prestressing system.