• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.173-176
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• 2006

There are many kinds of protection methods for marine structures by using and environmental condition. Coating protection method, one of these methods is being widely adopted to both all ground and marine structures. In this study, by adding some additives such as Zn powder(Zn), carbon black(CB) to epoxy anti-corrosive paint, the effect to promote corrosion resistance was investigated with electrochemical method. Corrosion potentials with additives shifted to negative direction than no additive. However passivity current density increased than no additive except for Zn(20)+CB(10), especially, additive of Zn(20)+CB(10) showed the smallest passivity current density. Polarization resistance of Zn(20)+CB(10) by both cyclic voltammogram and impedance measurement was the largest value than other additives. And also surface phenomenon by adding Zn(20)+CB(10) was observed a good add condition not showing bubbling than other additives.

• 한국국방경영분석학회지
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• 제3권1호
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• pp.83-96
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• 1977

The combustion chamber and nozzle of an end burning, small spherical rocket is designed. A spherical external shape has a number of advantages such as fixed center-of-gravity and minimum aerodynamic precession torques during flight and a better mass distribution for gyro-stabilization as contrasted to a conventional ogive rocket shape. It is shown that the cross-sectional variation of the end burning solid propellant with length is an exponential geometry to provide a constant thrust-weight ratio of the rocket device during the propellant burning period, and that the factors which affect the attainment of the constant relationship of thrust to weight in the design are the initial propellant area, initial weight of the rocket and propellant density. The measurement of the transient thrust in the ground static test using black powder propellant supports the predicted results. A wind tunnel having a $30{\times}30{\times}75cm$ test section and Mach number 0.11 is constructed, and a simple balance-type device is designed for the measurement of the drag of a spinning sphere. The experimental results indicate that the. spinning has no effect on the magnitude of the drag up to the Reynolds number $3{\times}10^5$. Numerical computation of the flight trajectories for various launching angles is presented, and the gyro-stabilization of spinning sphere is discussed.

• 한국정밀공학회지
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• 제22권10호
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• pp.121-128
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• 2005

The research on electromagnetic shielding has been advanced for military applications as well as for commercial products. Utilizing the reflective properties and absorptive properties of shielding material, the replied signal measured at the rear surface or at the signal source can be minimized. The shielding effect was obtained from materials having special absorptive properties and structural characteristics such as stacking sequence. Recently researchers studied the electromagnetic properties of nano size particles. In this research {glass fiber}/{epoxy}/{nano particle} composites(GFR-Nano composites) was fabricated using various nano particles, and their properties in electromagnetic shielding were compared. For the visual observation of the nano composite materials, SEM(Scanning Electron Microscope) and TEM(Transmission Electron Microscope) were used. For the measurement of electromagnetic shielding, HP8719ES S-parameter Vector Network Analyser System was used on the frequency range of 8 GHz${\~}$12GHz. Among the nano particles, carbon black and Multi-Walled Carbon Nano-Tube (MWCNT) revealed outstanding electromagnetic shielding. Although silver nano particles (flake and powder) were expected to have effective electromagnetic shielding due to their excellent electric conductivities, test results showed little shielding characteristics.

• Korean Chemical Engineering Research
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• 제43권1호
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• pp.170-175
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• 2005

자외선을 대체하여 형광등이나 자연광(햇빛)을 이용하여 $TiO_2$로 수은제거 실험을 수행하였다. 반응기는 내부의 $TiO_2$가 광원에 최대한 노출되도록 디자인하였으며 회전할 수 있게 하였다. 반응기 내부에 $TiO_2$와 유리비드를 섞어 넣어 기상수은과 흡착제와의 접촉면적을 최대화하였다. 광촉매가 가장 활성을 잘 보이는 UV black light뿐 아니라 실험에 사용된 모든 광원에서 99% 이상의 수은제거효율을 보였다. 인체에 무해하고 경제성이 좋은 형광등이나 태양광하에서도 99% 이상의 수은제거효율을 얻었다.

• 한국세라믹학회지
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• 제31권9호
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• pp.1069-1075
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• 1994

When ceramics are used as the parts of an engine and a machine, the tribological properties are very important. For the preparation of the resistance material for wear applications by the method of Reaction-Bonded Sintering, metal silicon and carbon black are mixed up into SiC powder, and Al2O3 and Fe2O3 are put as an additive. As the general properties, the bending strength and water absortion are measured in the normal temperature and the phase changies are investigated with XRD. The property of the resistance for wear applications is measured with the amount of friction and wear, friction coefficient and maximum asperties. And, the surface of wear is observed with SEM. With the results of this study, the optimal mol ratio of Si : C and the suitable quantity of the mixture of SiC are 7 : 3 and 40 wt%, respectively. In the case of the addition of Al2O3 (2 wt%), the resistance for friction and wear applications is prominent. The bending strength showed the highest peak when Al2O3 (4 wt%) and Fe2O3 (4 wt%) were added. The properties of friction and wear were related with the propagation velocity of crack rather than the bending strength.

• 한국식품영양과학회:학술대회논문집
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• 한국식품영양과학회 2001년도 International Symposium on Food,Nutrition and Health for 21st Century
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• pp.170-177
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• 2001

The objective of this study was to improve the qualities of Saengsik (substitute meal formulated with uncooked cereal powder) such as functionality, safety and sensory preference by using Lactic Acid Bacteria (LAB). The optimum formulation of fermented Saengsik (substitute meal) was verified as $40\%$ of fermented brown rice, $13\%$ of fermented job tears, $5\%$ of yellow soybean, $5\%$ of waxy rice, $5\%$ of sorghum, $3\%$ of Seumok bean, $1\%$ of sesame, $3\%$ of barley, $2\%$ of red bean, $5\%$ of prosomillet, $2\%$ of foxtail millet, $9%$ of black rice, $3\%$ of buckwheat, $1\%$ of chestnut, $2\%$ of pumpkin, $3\%$ of peanut. Fermented Saengsik decreased significantly serum glucose in STZ-induced diabetic rats. However, serum lipid levels were not affected by fermented Saengsik. In rats fed with high-fat diet, serum triglyceride level was slightly decreased and the contents of liver triglyceride were significantly decreased by supplementation of fermented Saengsik.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2004년도 춘계학술대회
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• pp.247-257
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• 2004

Electrodes were fabricated based on activated carbon powder BP-20, conducting agent such as Super P, vapor grown carbon fiber (VGCF) and acetylene black (AB), and the mixed binders of flexible poly(vinylidenefluoridehexafluoropropylene) [P(VdF-co-HFP)] and cross linking dispersion agent of polyvinylpyrrolidone (PVP) to increase mechanical strength. According to impedance measurement of the electrode with the addition of conducting agent, we found that it was possible to charge rapidly by the fast steady-state current convergence due to low equivalent series resistance (AC-ESR, fast charge transfer rate at interface between electrode and electrolyte and low RC time constant. The self-discharge of unit cell showed that diffusion process was controlled by the ion concentration difference of initial electrolyte due to the characteristics of Electric Double Layer Capacitor (EDLC) charged by ion adsorption in the beginning, but this by current leakage through the double-layer at the electrode/electrolyte interface had a minor effect and voltages of curves were remained constant regardless of electrode material. We found that the 2.3V/230F grade EDLC would be applied to industrial safety usage such as uninterrupted power supply (UPS) because of the constant DC-ESR by IR drop regardless of discharge current.

• 한국결정성장학회지
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• 제3권1호
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• pp.31-36
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• 1993

FZ법을 이용하여 Tourmaline ($NaFe_3Al_6B_3Si_6O_{27}F_4$) 단결정을 성장하였다. 성장조건으로 회전수 상호 역방향으로 20~30rpm, 성장속도 2~5mm/hr로 조절하였다. 성분 원소 중 전이금속 원소가 존재하여 dopant는 첨가하지 않았다. 원료봉은 $1000~1100^{\circ}C$에서 소결하였고 이 온도보다 고온의 영역에서는 F등의 휘발원소의 휘발로 인해 원료봉을 제작하기가 어려웠다. 성장된 결정은 어두운 색을 띄고 있었고 길이 60~50mm, 직경 5~6mm였다. 결정의 원료에 대하여 XRD 분석을 통하여 Tourmaline 조성을 확인하였고 FTIR로 성분의 결합상을 보았다.

• 한국세라믹학회지
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• 제26권3호
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• pp.416-422
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• 1989

The particle size of synthesized SiC powders was decreased with increasing carbon content when the mixture of carbon and silica was carbonized at 1, 45$0^{\circ}C$ after hydrolysis of the mixture with the ranges of 3.1 to 3.5 in the mole ratio of Carbon/Alkoxide. The reacted fraction of $\beta$-SiC nearly had nothing to do with the mole ratio of Carbon/Alkoxide. When the reaction was made by adding 0.5wt% additives in the composition of 3.1 in the mole ratio of carbon/alkoxide, the additives decreased the yield of $\beta$-SiC and its sequence was Ba2O3>B>Fe>Al>Al2O3>Si. The effect of additives promoted the transformation of $\beta$-SiC to $\alpha$-SiC form and shwoed the increasing tendency of lattice constant. The two colors of $\beta$-SiC powder came out : one was the black grey with addition of Al, Al2O3 and B the other the light grey with addition of Fe, B2O3 and Si.

• 한국식품영양학회지
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• 제35권6호
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• pp.543-551
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• 2022

There has been increased interest in lignans due to their potential effect in reducing the risk of developing several diseases. To evaluate lignan contents, sensitive and accurate methods should be developed for their quantification in food. The present study aimed to validate a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of 5 lignans: lariciresinol (Lar), matairesinol (Mat), pinoresinol (Pin), secoisolariciresinol (Seco), and syringaresinol (Syr). The validation included selectivity, linearity, recovery, accuracy, and precision. The method was proved to be specific, with a linear response (R²≥0.99). The limits of detection were 0.040~0.765 ㎍/100 g and the limits of quantification were 0.114~1.532 ㎍/100 g. Recoveries were 90.588~109.053% for black sesame powder. Relative standard deviations of repeatability and reproducibility were below 5%. Total lignan contents of roasted coffee bean, oat, and blacksoy bean were 105.702 ㎍/100 g, 78.965 ㎍/100 g, and 165.521 ㎍/100 g, respectively. These results showed that LC-MS/MS analysis would be effective in producing acceptable sensitivity, accuracy, and precision in five lignan analyses.