• Journal of Korean Society of Forest Science
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• v.98 no.3
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• pp.284-289
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• 2009

This study estimated the fiberboard demand using VAR and econometric model, and compared the prediction accuracy of the two models. And the variance decomposition and impulse response were analyzed using VAR model, and predicted the fiberboard demand. The VAR model was specified with lagged dependent variable, lagged own price, lagged construction product, dummy. The econometric model was specified with own price, substitute price, construction product, dummy. The dummy variable reflected the abrupt decrease in fiberboard demand in the late 1990's. The results showed that the fiberboard demand prediction can be performed more accurately by VAR model than by econometric model. In the VAR model of fiberboard demand, after twelve months, the construction product change accounts for about fifty percent of variation in the demand, and the own price change accounts for about thirty percent of variation in the demand. On the other hand, the impact of a shock to the construction product is significant for about twelve months on the demand of fiberboard, and the impact of a shock to the own price is significant for about six months on the demand of fiberboard.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1009-1012
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• 2008

The fiber dispersion performance in fiber-reinforced cementitious composites is a crucial factor with respect to achieving desired mechanical performance. However, evaluation of the fiber dispersion performance in the composite PVA-ECC(Polyvinyl alcohol-Engineered Cementitious Composite) is extremely challenging because of the low contrast of PVA fibers with the cement-based matrix. In the present work, an enhanced fiber detection technique is developed and demonstrated. Using a fluorescence technique on the PVA-ECC, PVA fibers are observed as green dots in the cross-section of the composite. After capturing the fluorescence image with a Charged Couple Device(CCD) camera through a microscope. The fibers are more accurately detected by employing a series of process based on a categorization, watershed segmentation, and morphological reconstruction.

• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.589-597
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• 2009

High Performance Fiber-reinforced Cement Composite (HPFRCC) shows the multiple crack and damage tolerance capacity due to the interfacial bonding of the fibers to the cement matrix. For practical application, it is needed to investigate the fractural behavior of HPFRCC and understand the micro-mechanism of cement matrix with reinforcing fiber. This study is devoted to the investigation of the AE signals in HPFRCC under monotonic and cyclic uniaxial compressive loading, and total four series were tested. The major experimental parameters include the type and volume fraction of fiber (PE, PVA, SC), the hybrid type and loading pattern. The test results showed that the damage progress by compressive behavior of the HPFRCC is a characteristic for the hybrid fiber type and volume fraction. It is found from acoustic emission (AE) parameter value, that the second and third compressive load cycles resulted in successive decrease of the amplitude as compared with the first compressive load cycle. Also, the AE Kaiser effect existed in HPFRCC specimens up to 80% of its ultimate strength. These observations suggested that the AE Kaiser effect has good potential to be used as a new tool to monitor the loading history of HPFRCC.

• Composites Research
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• v.32 no.1
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• pp.50-55
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• 2019

In this study, we investigated the effect of fiber alignment in helicoidal structure on the mechanical properties of biomimetic fiber-reinforced composites. Using finite element analysis, circular biomimetic fiber composites were designed and studied. Various amounts of pressure loads were applied to a surface of the composites, and then bending and failure behaviors of the composites were analyzed. The results showed various failure morphologies according to the orientation of the fibers, and it turned out that the fiber alignment in helicoidal structure significantly improved the bending strength of the composite under pressure loading. This was because the fiber alignment in various directions for each layer dispersed effectively the fracture energy from the external load into multiple directions.

• Composites Research
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• v.24 no.4
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• pp.1-4
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• 2011

In this work, we successfully fabricated graphene oxide (GO) and GO-based PMMA composite fiber and nylon films. Dynamic mechanical and tensile properties of PMMA-GO composite fiber showed that GO is efficient reinforcement for polymer matrices. However, Nylon 6,6-GO composite films showed low reinforcement efficiency in terms of dynamic mechanical and tensile properties due to the colloid instability of GO in formic acid at a low pH level.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.431-432
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• 2010

In this study, The Mineral Admixture(Fly-ash, GGBFS) using Nylon Fiber to improve the dispersibility, in order to improve the performance of concrete, were applied to Self-Consolidating Concrete(SCC) needed high strength and fluidity. Especially, the GGBFS reachs the higher satisfaction than other admixture.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2001.04a
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• pp.40-44
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• 2001

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2001.11a
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• pp.15-19
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• 2001

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2007.11a
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• pp.47-48
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• 2007

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.91-91
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• 2011

폴리프로필렌(PP)은 고결정성 범용수지로서 염색성, 내열성, 촉감 등의 문제로 의류용 소재로는 부적합하여 초기에는 카펫용 섬유로서 가염형 폴리프로필렌 섬유가 상업화 되었지만 성공하지는 못하였다. 그 후, 섬유 산업도 의류용 외의 산업자재, 생활 자재 분야 등이 성장함에 따라, 폴리프로필렌 섬유의 수요가 확대되었다. 최근들어 스포츠 액티브 의류가 일반의류 트렌드로 들어오면서 기능성 섬유가 요구되고 이 분위기에 맞춰 다시 한번 폴리프로필렌 섬유의 의류화가 요구되는 시점이 되었으며 섬유중 에너지 소비량이 가장 적고, 쉽게 재용해할 수 있으며 소각시 유해 가스발생량이 매우 적은 특징등이 있기 때문에 지구 환경보호의 입장에서 폴리프로필렌 섬유가 재검토되고 있다. 이번 실험은 분산염료를 이용하여 농도별, 온도별, 시간별, 후처리시 시간과 온도의 변화로 가염 PP/PET 섬유의 염색특성을 알아보기 위해 실험 진행하였다. 실험에 사용되는 시약은 1급으로, $CH_3COOH$, NaOH, $Na_2S_2O_4$이며, 조제는 분산제, 정련제를 사용하였다. 먼저 온도별 실험에서 $40^{\circ}C$에서 승온하여 각각 $100^{\circ}C$, $110^{\circ}C$, $120^{\circ}C$, $130^{\circ}C$에서 온도에 따라 염색되는 정도를 알아보았다. 가장 높은 흡진을 보이는 온도에서 각각 40min, 50min, 60min, 70min 염색 유지시간 실험을 하여 염색이 안정되는 시간을 측정하였다. 위의 실험 결과 최적의 조건으로 염색농도에 따른 Build up 실험을 진행하였다. 가염 PP/PET 섬유는 일반 Polyester처럼 $120{\sim}130^{\circ}C$에서 가장 높은 염색농도 값(K/S)을 보인다. 또한 $130^{\circ}C$에서의 유지시간에서는 50 min 이상 진행시 더 이상의 흡진이 없거나, 염료의 탈락이 있음을 알수 있다. Build up 실험에서는 8.0%까지 실험하였지만, 결과는 그 이상농도를 사용하여도 염색은 가능함을 알 수 있었다. 후처리에 대한 실험에서 염료에 따라 차이가 있지만 크게 영향을 받지 않는 것으로 보이며, 제품성 평가 결과를 보면 후처리를 했을 경우 견뢰도가 우수한 것을 알 수 있었다.