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콘크리트 보강용 유리섬유/마섬유 복합재료 보강재료의 인장특성 평가
오리온 ( Ri-on Oh ),전지홍 ( Ji-hong Jeon ),박찬기 ( Chan-gi Park ) 한국농공학회 2014 한국농공학회 학술대회초록집 Vol.2014 No.-
본 연구의 유리섬유/마섬유 복합재료 보강재의 인장특성을 평가하여 콘크리트 구조물의 적용가능성을 평가하는 것이다. 본 연구에서는 천연마섬유는 실란으로 표면을 코팅하지 않았을 때와 실란으로 처리하였을 때를 비교하여 실험을 진행하였다. 천연마섬유의 실란처리 방법은 다음과 같다. 1) 메탄올 : 증류수 = 95:5(무게비) 공용매를 제조한다. 2) 실란커플링제를 0.8wt%희석하고, 2) 아세트산을 사용하여 PH 4.0에 고정시키고 1시간 가수분해하여, 3) 상온에서 완전 건조시켰다. 유리섬유와 천연마섬유, 비닐에스터수지의 비율은 각각 70:0:30, 49:21:30, 35:35:30, 21:49:30, 0:70:30으로 결정하였다. 그러나 실란처리를 하지 않은 보강재의 경우 천연마섬유 70%로 들어가고 30%로가 비닐에스터 수지로 구성되는 경우 수지함침에 문제가 발생하여 제조가 불가능하였다. 보강재료의 생산은 압출성형과 블레이딩공정을 결합한 형태의 생산시스템을 이용하여 제조하였다. 인장특성은 ACI 440K에 의한 인장시험을 실시하였다. 유리섬유/천연마섬유 복합재료 보강재 인장시험 결과 천연마섬유 혼입률이 감소할수록, 유리섬유의의 혼입률이 증가할수록 인장강도는 증가하는 경향을 보였다. 또한 실란처리가 된 바이오 복합재료 보강재의 인장강도가 실란처리를 하지 않은 복합재료와 비교하여 인장강도가 크게 나타났다. 이와 같은 이유는 실란처리를 매트릭스 수지의 섬유의 함침을 도와 바이오 복합재료 보강재 제조시 수지와 섬유와의 사이의 부착계면을 강화하는 효과가 있기 때문이다.
Fracture and long-term aging characteristics of GFRP clamping plates for improved movable weirs
Oh, Ri-On,Park, Chan-Gi RAPRA 2019 POLYMERS AND POLYMER COMPOSITES Vol.27 No.3
<P> In this study, the durability of movable weirs was improved by replacing steel clamping plates with glass fiber-reinforced polymer (GFRP) material. Because the clamping plates of movable weirs are always in contact with water, the service life of weirs is reduced due to corrosion. Other environmental conditions also degrade movable weirs, such as exposure to continuous inundation, dry environments, repeated dry and wet conditions, and chemical environments. This study evaluated the absorption, fracture, and long-term aging properties of GFRP clamping plates for improved movable weirs. Absorption increased with immersion time in 60°C tap water, sodium sulfate (Na<SUB>2</SUB>SO<SUB>4</SUB>) solution, or calcium chloride (CaCl<SUB>2</SUB>) solution. However, the total absorption for 50 days and 100 days exposure was low, less than 0.50% and 0.62%, respectively. In fracture load tests, the GFRP clamping plates showed the largest reduction in strength after exposure to the CaCl<SUB>2</SUB> solution; 70% and 67% of the control load were retained for exposures of 50 days and 100 days, respectively. After exposure to both tap water and the Na<SUB>2</SUB>SO<SUB>4</SUB> solution, the GFRP clamping plates showed residual strengths of 77% and 69% after 50 days and 100 days exposure, respectively. The GFRP clamping plates showed 74% and 71% residual strength after exposure to repeated freeze-thaw environments for 50 days and 100 days, respectively, and 80% residual strength after exposure to all other environments for 50 days or 100 days. Both vertical and horizontal cracks were generated before fracture after exposure to an environment involving direct contact with moisture. Without moisture, only horizontal cracks were generated before fracture. </P>
이산화티타늄을 이용한 대기정화 블록의 질소산화물 제거 성능 평가
오리온 ( Oh Ri-on ),김황희 ( Kim Hwang-hee ),박성기 ( Park Sung-ki ),차상선 ( Cha Sang-sun ),박찬기 ( Park Chan-gi ) 한국농공학회 2020 한국농공학회논문집 Vol.62 No.5
This study evaluated the nitrogen oxide (NO<sub>x</sub>) removal efficiency by air purification concrete blocks with titanium dioxide (TiO<sub>2</sub>). The concrete in the mixtures had a 30% water:cement ratio, to which TiO<sub>2</sub> was added at 0%, 5%, and 10% of cement weight. The compressive strength reduction rate and removal efficiency of NO<sub>x</sub> were investigated. The result of the compressive strength test in the study indicated that addition rate of TiO<sub>2</sub> did not lead to signifcant effect. In terms of the average removal efficiency of NO<sub>x</sub>, mix No. 1 using a TiO<sub>2</sub> mixing ratio of 0% had a removal efficiency of 0 .57% on average; thus, the removal effect was not significant. For the other samples prepared by mixing, the average removal efficiencies for mix No. 2 (5% TiO<sub>2</sub>) were 58.86% and 62.05% for normal and washing surface treatments, respectively, and those of sample No. 3 (10% TiO<sub>2</sub>) were 59.94% and 67.61%. mixs No. 4 (5%) and No. 5 (10%), in which TiO<sub>2</sub> diluted with distilled water was sprayed onto the block surface, had an average NOx removal efficiency of 61.72% and 68.48%, respectively. In terms of NO<sub>x</sub> removal efficiency, Mixs No. 3 and No. 5 with 10% TiO<sub>2</sub> were better than Mixs No. 2 and No. 4 with 5% TiO<sub>2</sub>. In addition, analyzing the NO<sub>x</sub> removal efficiency results from the fixing method, it was capable to apply mixing (washing) and the diluted spray methods. Therefore, it was found that the diluted spray method applied in this study can be employed in any manufacture of air purification concrete blocks.
Composite Measures of Supercomputer Technology
( Nam-gyu Kim ),( Noo Ri On ),( Myoung-ju Koh ),( Jongsuk Ruth Lee ),( Keun-tae Cho ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.8
We have developed composite measures of supercomputer technology, reflecting various factors of supercomputers using Martino’s scoring model. CPUs, accelerators, memory, interconnection networks, and power consumption are chosen as factors of the model. The weight values of the factors are derived based on a survey of 129 domestic and international experts. The measured values are then standardized to integrate measurement units of the factors in the model. This model has been applied to 50 supercomputers, and rank correlation analysis was performed using representative measures. As a consequence, the ranking drastically changes except for the 1st and 2nd supercomputers on the TOP500. In addition, the characteristics of memory and interconnection networks influence the ranking, and the results demonstrate that the proposed model has low correlations with HPL and HPCG but a high correlation with Green500. This indicates that power consumption is an important factor that has a significant effect on the measures of supercomputer technology. In addition, it is determined that the differences between the HPL ranking and the proposed model ranking are influenced by power consumption, CPU theoretical peak performance, and main memory bandwidth in order of significance. In conclusion, the composite measures proposed in this study are more suitable for comprehensively describing supercomputer technology than existing performance measures. The findings of this study are expected to support decision making related to management and policy in the procurement and operation of supercomputers.
Lee, Na-Ri,On, Hwa-Young,Jeong, Min-Seong,Kim, Chi-Kyung,Park, Yong-Keun,Ka, Jong-Ok,Min, Kyung-Hee The Microbiological Society of Korea 1997 The journal of microbiology Vol.35 No.2
Alcaligenes xylosoxydans strain SMN3 capable of utilizing biphenyl grew not only on phenol, and benzoate, but also on salicylate. Catabolisms of biphenyl and salicylate appear to be interrelated since benzoate is a common metabolic intermediate of these compounds. Enzyme levels in the excatechol 2. 3-dioxygenas which is meta-cleavage enzyme of catechol, but did not induce catechol 1, 2-dioxygenase. All the oxidative enzymes of biphenyl and 2, 3,-dihydroxybiphenyl (23DHBP) were induced when the cells were grown on biphenyl and salicylate, respectively. Biphenyl and salicylate could be a good inducer in the oxidation of biphenyl and 2, 3-dihydroxybiphenyl. The two enzymes for the degradation of biphenyl and salicylate were induced after growth on either biphenyl or salicylate, suggesting the presence of a common regulatory element. However, benzoate could not induce the enzymes responsible for the oxidation of these compounds. Biphenyl and salicylate were good inducers for indigo formation due to the activity of biphenyl dioxygenase. These results suggested that indole oxidation is a property of bacterial dioxygenase that form cis-dihydrodiols from aromatic hydrocarbon including biphenyl.