• Korean Journal of Food Science and Technology
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• v.32 no.6
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• pp.1298-1305
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• 2000

Potato starches were crosslinked with 0.1, 0.5, 1.0, and 2.0% epichlorohydrin. Starch/polyethylene(PE) cast films were prepared to contain 5% of the crosslinked potato starch. Mechanical properties and degradability of these films were measured and compared to those of the films containing native potato starch. Mechanical strength of the films containing crosslinked potato starch was higher than that of the film containing native starch. Thermal degradability measured by a FT-IR and an Instron showed that crosslinked starch/PE films degraded faster than native starch/PE films. Biodegradability of the starch/PE films was accelerated by the addition of crosslinked starch to the PE films.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.6
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• pp.633-640
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• 2011

In this study, the stabilization of an edge flame and the intensity variation of a diffusion branch were investigated using a multi-slot combustor under conditions of high temperature and small fuel-concentration gradient (FCG). The combustor consists of three narrow channels: a quartz channel and two side-heating combustors. For the accuracy of this experimental study, quantitative analysis was carried out for each boundary condition. Stable edge flames could be observed under high-temperature conditions by controlling the FCG and fuel dilution ratio. Moreover, it was found that the intensity of the diffusion flame was increased by increasing the temperature of the mixture. On the contrary, the intensity of the diffusion flame was decreased by increasing the dilution ratio. It was also found that a propane flame is more sensitively affected by these experimental parameters than a methane flame.

• Elastomers and Composites
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• v.43 no.4
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• pp.253-258
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• 2008

In this study polyamide 6,6 based thermoplastic composite with graphite and carbon black had been examined feasibility for separators of fuel cell which requires good mechanical and electrical properties with gas impermeability. The effects of molding pressure and filler content on the properties of the composite were investigated. Maximum flexural modulus was obtained about 80 wt% graphite, while electrical conductivity increased with graphite content. Flexural strength increased with molding pressure and tended to level-off from $400\;kgf/cm^2$. Molding pressure did not affect the electrical conductivity. The addition of carbon black enhanced the electrical conductivity of the composite. Mechanical properties were decreased under acidic condition.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.157-158
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• 2008

친환경적인 분산기법으로 강력초음파 분산기법이 최근에 여러연구자들에 의해 적용되어 그 성과를 나타내고 있다. 에폭시-층상실리케이트 제조기법 중 가장 중요한 물성향상이 동반 상승되는 경우 분산처리를 통한 나노콤포지트 제조에 있다. 분산능력의 최적상태를 찾기 위해 초음파 적용시간을 4가지 적용시간을 달리하여 제조된 나노콤포지트 기계적, 전기적강도를 측정하여 와이블 확률분포 통계처리를 한 결과 전기적 절연파괴강도와 기계적 굴곡강도에서 최적의 분산상태를 얻을 수 있었다.

• Journal of Forest and Environmental Science
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• v.22 no.1
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• pp.27-31
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• 2006

Sedimentation characteristics such as SS, COD removal efficiency of wastewater in the toilet paper mill using recycled paper were examined by zeta potential. Optimum dosage of coagulant were determined by turbidity, SS, COD and then equation for treatment efficiency was suggested. Mechanical strength of floc was determined by turbidity.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.160-165
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• 2009

연료전지 분리판은 연료전지 스택을 구성하는 부품 중에서 가장 많은 수량이 사용되는 부품의 하나로서 연료전지의 출력밀도(Power Density, W/L), 비출력(Specific Power, W/kg) 및 가격($/kWe) 관점에서 가능한 저가의 소재 및 제조공정으로 경량, 박형화가 이루어져야 하는 핵심 부품이다. 이러한 저가의 경량, 박형화 분리판 개발의 전제조건은 연료전지 스택에서 요구하는 다양한 물성, 장기수명 및 신뢰성은 나타내는 내구성을 만족해야 하는 것이다. 이렇듯 연료전지 분리판은 다음과 같은 요구 조건을 만족해야 한다. 높은 전기전도도, 전기화학적 부식 저항성, 화학적 안전성, 가스 기밀성, 기계적 강도 및 가공성 등이라 하겠다. 본 연구에서는 분리판의 요구 조건을 만족할 수 있는 분리판을 제작하기 위하여 고분자 복합소재(PCB; Printed Circuit Board)를 이용하여 전기도금을 통해 Cu/Au(1st PCB 분리판)과 Cu/Ni/Au(2st PCB 분리판)을 코팅하여 분리판을 제작하였다. 제조된 분리판을 이용하여, 접촉저항, 부식특성, 가스 기밀성, 기계적 강도를 분석하였으며, 단위전지를 제작 하여 상용 Graphite 분리판과 성능을 비교분석하였다.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.363-366
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• 2012

본 연구에서 NaOH, Acetic acid, Silane 처리는 천연섬유와 matrix간의 계면 결합에 불리하게 작용하는 wax, lignin, hemicellose 등을 제거하기 위한 방법 중의 하나이다. 이러한 화학적 처리에 따른 왕겨 분말의 기계적 특성 변화를 관찰하였다. Scaning electron microscopy(SEM)으로 관찰한 표면의 상태가 NaOH, Acetic acid, Silane 처리를 하였던 왕겨 분말이 처리를 하지 않았던 왕겨 분말보다 비교적 깨끗해지고, 크랙이 발생함을 확인하였다. 또한 전처리가 된 상태에서 PP와 20, 30, 40%의 비율로 복합재를 제조하여 Universal Testing Machine(UTM)으로 인장강도, 굴곡강도, 굴곡탄성률을 측정하였다. 또한, 왕겨의 입도 사이즈에 따라서 어떻게 변화되는지 알아보았다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.184-185
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• 2022

This study researched the effect of graphene nanoribbons (0.05 wt%) on cement-based materials' mechanical and electrical properties. The results were compared with the ordinary Portland cement (OPC) paste and OPC paste with the same content of carbon nanotubes. The experiment results showed that after curing for 28 days, the compressive and splitting tensile strength of the sample with graphene nanoribbons were increased by 17.8% and 6.6% compared to OPC paste, and its reinforced effect for cement-based materials was superior to carbon nanotubes. Besides, due to the excellent electrical properties of graphene nanoribbons, the sample reinforced by graphene nanoribbons had a lower electrical resistivity (135.5 Ω·m) than OPC paste (418.5 Ω·m) and paste with carbon nanotubes (175.5 Ω·m). This proved the promising application of graphene nanoribbons on cement-based materials.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.14-20
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• 2017

Ultra high performance concrete is inevitably used in case of skyscraper and super long span bridge. In general, the flexural and the tensile strengths of concrete are lower than the compressive strength, so brittle cracks occur and energy absorption ability is lowered. In order to solve this problem, this study is intended to examine the effect of the steel fiber volume fraction and aspect ratio on the mechanical properties of ultra high performance concrete. In series I, 20-mm straight steel fiber was added with a volume fraction of 0, 1.0, 1.3, 1.5 and 2.0%. In series II, 16-mm steel fiber was added with a volume fraction of 0, 1, and 1.5%, and then mechanical properties were examined according to aspect ratio. In the results of experiment, a difference in compressive strength was insignificant. However, regarding the flexural strength and tensile strength, as the volume fraction and aspect ratio increased, flexural performance and tensile performance improved.

• Journal of the Korean Wood Science and Technology
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• v.21 no.4
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• pp.55-59
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• 1993

한국의 중서부 지역에서 주로 벌채한 잣나무 간벌 제재목을 경기도 광주 소재 제재소에서 무작위로 추출하여 구입하였다. 본 연구는 휨강도 시험을 표준 시험 방법에 의하여 실시하였다. 각 무결점 시편으로부터 측정한 영 계수와 휨 강도에 대하여 이론적 통계 분포인 정상 분포, Log-normal 분포, Weibull 분포를 계산하여 비교하였다. Weibull 분포가 휨영계수 및 휨강도 모두에 적합하였으며, Log-normal 분포는 영계수 분포에 대한 이용에 적합하였다. 휨강도 분포에서는 Normal 분포가 Log-normal 분포보다 적합하다.