• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.214-219
• /
• 2004

Crack tip behavior of single mode loading condition(mode I)depend on tensile loading component but one of mixed mode loading condition(mode I+II) have influenced on shear loading component like the practical structure. Because crack closure is caused by shear loading component under mixed-mode loading a research on the behavior in the stage of crack initiation and propagation require to be evaluate about crack closure effect by fatigue crack surface friction. For that reasion we examined the behavior at the crack tip by direct measuring method. Measured behavior at the crack tip was analyzed through vector crack tip displacement. As a result, crack propafation equation was corrected by considering with crack closure effect. In addition we compared fatigue fracture crack surface and crack closure level.

• 한국잠사곤충학회지
• /
• 제6권
• /
• pp.34-38
• /
• 1966

본 실험은 제사용수, 견층, 생사중의 철분을 분석하여 정량하고, 제사용수중의 철분 함유량에 의한 생사내의 철분 함유량 변화 및 생사에의 착색정도에 대해서 조사하였다. (1)우리나라 제사용수는 대개 0.01~0.77PPM 범위내의 철분을 함유하고 있으며 평균 0.23PPM이 함유되어 있다. (2) 원수가 정수인 경우는 하천수인 경우에 비하여 2배 정도의 더 많은 철분을 함유하고 있다. (3) 견사(원료견)중의 철분 함유량(Fe$_2$O$_3$ 0.0096%)과 생사중의 철분 함유량(Fe$_2$O$_3$ 0.0084%)은 거의 비슷하나 회분량에 있어서는 견사가 생사의 약 2배, 그리고 회분중의 함유량은 생사가 견사에 비해 2배 정도 많았다. (4) 용수중의 철분 함유량은 자견, 조사시 철분의 용해 및 흡착에 크게 영향을 준다. 즉 철분 함유량이 적은 용수로 자견, 조사를 할 때는 견사로부터의 철분 용해량이 증가하지만 철분 함유량 0.4PPM 이상의 용수를 사용한 경우는 용수로부터의 흡착량이 더 많아져서 생사는 견사(원료견)가 가지고 있는 철분 함량보다도 더 많은 철분을 함유하게 된다. (5) 용수중의 철분은 생사를 미로 착색시키며 용수중의 철분 함유량이 증가하는데 따라 착색의 농도가 짙어진다. 철분은 소량이어도 착색력이 강하나 망강은 다량이 존재하여도 생사를 착색시키는 힘이 미약하다.

• Elastomers and Composites
• /
• 제57권3호
• /
• pp.100-106
• /
• 2022

Waterborne polyurethane-acrylate(WPUA) dispersions were prepared by surfactant-free emulsion polymerization in a two-step process. In the first step, polytetrahydrofuran, isophorone diisocyanate, dimethylol proponic acid, and 2-hydroxyethyl methacrylate were used to synthesize a vinyl-terminated polyurethane prepolymer. In the second step, styrene, methyl methacrylate, butyl acrylate, and different multi-functional crosslinkers were copolymerized. 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, and pentaerythritol tetraacrylate were used as the crosslinkers, and their effect on the mechanical and thermal properties of WPUA was investigated. Overall, as the number of functional groups of the cross-linker increased, the gel fraction improved to 79.26%, the particle size increased from 75.9 nm to 148.7 nm, and the tensile strength was improved from 5.86 MPa to 12.40 MPa. In thermal properties, the glass transition temperature and decomposition temperature increased by 9.9℃ and 18℃, respectively. The chemical structures of the WPUA dispersions were characterized by Fourier-transform infrared spectroscopy. The synthesized WPUA has high potential for applications such as coatings, leather coatings, adhesives, and wood finishing.

• Journal of Ginseng Research
• /
• 제15권3호
• /
• pp.167-170
• /
• 1991

Radiation protective fraction was Isolated and partially purified from Korean white ginseng. The effect of the fraction was studied on the cell survival of W-damaged CHO-Kl cells. As a result, it was found that the fraction increased the survival rate of damaged cells significantly within the dose range of which cytotoxicity did not appear This fraction was separated into two parts by adding butanol, namely the precipitated protein component and the butanol extract. Damaged cells were treated with each of these components and their survival rates were measured. The protein component demonstrated significant increase in the survival rates, while the butanol extract showed no such increment. These results suggest that the radiation protective effect of the ginseng fraction is originated from the butanol-precipitated protein component, not from the butanol-soluble compounds.

• 한국철도학회논문집
• /
• 제9권1호
• /
• pp.18-22
• /
• 2006

The dynamic characteristics of the current collection system are investigated by conducting a test run in which signals from accelerometers and load cells attached to the various parts of the pantograph are analyzed in both the time and frequency domains. The dynamic characteristics of the current collection system are found to be strongly influenced by the train speed; the fluctuation in the pantograph motion increases in direct proportion to the train speed. There exist two major fequency components in the pantograph motion related to the current collection, a speed-dependent component arising from the train traversing a span of the catenary, and a speed-independent component related to the pantograph resonant frequency. The train acceleration is also found to exert strong influence on the current collection system characteristics. The effect of the train motion is found to be stronger on the speed-dependent frequency component than on the speed-independent one.

• 한국콘텐츠학회:학술대회논문집
• /
• 한국콘텐츠학회 2003년도 추계종합학술대회 논문집
• /
• pp.213-217
• /
• 2003

이 논문에서는 MLP(Multilayer Perceptron)가 지닌 잡음 강건성에 대한 통계학적 분석을 하였다. 또한, MLP의 잡음 강건성을 향상시키기 위한 선형적 전처리 단계로써, ICA(independent component analysis)와 PCA(principle component analysis)를 고려하여, 이들이 지닌 잡음처리 효과를 분석한후, MLP와 접목시 나타나는 잡음 강건성의 향상 여부를 필기체 숫자 인식의 시뮬레이션으로 확인하였다.

• 융합보안논문지
• /
• 제6권4호
• /
• pp.161-169
• /
• 2006

최근 정보시스템의 발달에 따라, 다양한 정보시스템과 응용 소프트웨어의 개발이 이루어지고 있다. 하지만 정보시스템의 발달에 따른 역기능으로 많은 침해사고와 사이버해킹이 증가하는 추세이다. 이러한 정보화의 역기능을 차단하기 위해, 많은 기관에서는 정보시스템과 이를 보호하는 정보보호시스템의 운영과 관리를 위하여 많은 정보시스템 운영인력을 투입하고 있으나, 체계적 관리와 각 역할의 특성에 대한 분석부족으로 효율적인 운영에 많은 어려움을 겪고 있다. 본 논문에서는 정보시스템과 정보보호시스템 보안 및 관리 운영과 수행업무의 특성에 따라 정형화 된 Cause-Effect Model을 제시하도록 한다. 이 모델에서는 정보시스템과 정보시스템 운영자를 하나의 information Component로 간주한다. 본 논문에서 제시된 Cause-Effect Model의 각 단계에서 영향을 미치는 Human Factor의 세부 요소에 대한 영향도 분석을 통하여, 주어진 역할에 따라 최적의 human Resource의 관리와 배치가 가능할 것이다. 이러한 분석 및 접근 방법은 각 기관의 제한된 Resource 에 대한 효율적 운영이 가능하도록 하여, 기관의 정보시스템 운영과 악의적 침입에 대한 효율적인 방어를 가능하게 할 수 있다.

• Earthquakes and Structures
• /
• 제13권4호
• /
• pp.409-419
• /
• 2017

In order to analyze the vibration control effect of viscous damper in the concrete archaized buildings with lintel-column joints under seismic action, 3 specimens were tested under dynamic excitation. Two specimens with viscous damper were defined as the controlled component and one specimen without viscous damper was specified as the non-controlled component. The loading process and failure patterns were obtained from the test results. The failure characteristics, skeleton curves and mechanical behavior such as the load-displacement hysteretic loops, load carrying capacity, degradation of strength and rigidity, ductility and energy dissipation of the joints were analyzed. The results indicate that the load-bearing capacity of the controlled component is significantly higher than that of the non-controlled component. The former component has an average increase of 27.4% in yield load and 22.4% in ultimate load, respectively. Meanwhile, the performance of displacement ductility and the ability of energy dissipation for the controlled component are superior to those of the non-controlled component as well. Compared with non-controlled component, equivalent viscous damping coefficients are improved by 27.3%-30.8%, the average increase is 29.0% at ultimate load for controlled component. All these results reflect that the seismic performance of the controlled component is significantly better than that of the non-controlled component. These researches are helpful for practical application of viscous damper in the concrete archaizing buildings with lintel-column joints.

• 대한기계학회논문집
• /
• 제18권2호
• /
• pp.292-301
• /
• 1994

The resultant cutting force during machining with a worn tool is viewed as a decomposition of the cutting force into a cutting force component related to chip removal from the workpiece and into a component dependent on the contact force between the tool flank's wear land and the workpiece. The shear line method, in which the cutting force is considered proportional to the length of the shear line, is used to calculate the cutting force component for the removal of the chip, while the elastic effect of the workmaterial on the tool is taken into consideration to analyze the effect of tool flank wear. The predicted resultant cutting force, expressed as the sum of both components, is compared to experimental data obtained during wave-on-wave cutting.

• 한국응용약물학회:학술대회논문집
• /
• 한국응용약물학회 1998년도 Proceedings of UNESCO-internetwork Cooperative Regional Seminar and Workshop on Bioassay Guided Isolation of Bioactive Substances from Natural Products and Microbial Products
• /
• pp.179-179
• /
• 1998

We previously reported the hepato-protective effect of butanol soluble fraction of methanolic extract of Carthamus tinctorius L. Semen on carbon tetrachloride induced hepatotoxicity. In this study, the active component from the butanol soluble fraction was isolated by column chromatographic separation using Silica gel and Sephadex LH -20 and identified by spectroscopic methods such as Mass, $^1$H - NMR and $\^$13/C-NMR. The hepato-protective effect of the isolated active component on the CCl$_4$-induced liver damaged rats has been evaluated by performing blood chemical analysis and biotransformational enzyme analysis.