• Analytical Science and Technology
• /
• v.8 no.2
• /
• pp.195-203
• /
• 1995

Carbon and small amounts of alloying elements were added in Fe-5.7% Al ferromagnetic damping alloy. The specific damping capacities(SDC) of these alloys were investigated in relation to the grain size and the magnetic hysteresis loops. The behavior of carbon was analysed by XRD and EDS. These alloys showed characteristic damping nature of ferromagnetic damping materials. The alloying elements decreased SDC and especially the carbon was remarkable. The SDC was observed to be not related with the grain size but with the magnetic hysteresis loop area. The remarkable decrease of SDC by carbon addition was attributed to the locking migration of $90^{\circ}$ magnetic domain wall by the interstitial carbon in Fe-Al solid solution. However, the carbides also seems to decrease the SDC.

• Analytical Science and Technology
• /
• v.13 no.5
• /
• pp.573-583
• /
• 2000

Activated carbon fibers (ACFs) were prepared from various precursors of plantic, synthetic, and mixed fabrics of viscous rayon and cotton. Their adsorption performances of phenol and methylene blue in aqueous phase were evaluated through their adsorption isotherms, adsorption rates and breakthrough curves. The two adsorbates showed type I adsorption isotherm on ACFs. Adsorption rates to ACFs were 100 fold faster than to GAC. The effective diffusion coefficients of the adsorbates in ACFs were twenty fold greater than in GAC. The ACFs removed completely ten organic pollutants from a prepared water specimens through the 2nd column of a natural filtration method where 50 L of the water samples were treated.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.37 no.4
• /
• pp.296-301
• /
• 2001

Electro-Rheological (ER) fluids belong to a class of colloidal suspensions whose global characteristics can be controlled by the imposition of an appropriate external electrical field upon the fluid domain. The ER fluids for smart hydraulic system are a class of colloidal dispersion which exhibit large reversible changes in their rheological behavior when subjected to external electrical fields. This paper presents experimental results on mechanical properties of an ER fluids subjected to electrical fatigues. As a first step, ER fluid is made of methyl cellulose(MC) ingredient choosing 25% of particle weight-concentration. Following the construction of test for mechanical properties of ER fluid, the shear stress, dynamic yield stress and current density of the ER fluids are experimentally distilled as a function of electric field cycles. The mechanical properties test of operated ER fluids are distilled and compared with those of unused ER fluids.

• Analytical Science and Technology
• /
• v.23 no.2
• /
• pp.119-127
• /
• 2010

An effective method for the simultaneous analysis of ${\beta}$-lactams from surface water was established. After solid-phase extraction with HLB (Hydrophilic Lipohilic Balance) cartridge at pH 2, seven ${\beta}$-lactams (amoxicillin, ampicillin, penicillin G, cefaclor, cefadroxil, cefatrizine and cephradine) were determined using LC/ESI-MS/MS. In this newly established method, correlation coefficients ($r^2$) of calibration curves for seven ${\beta}$-lactams in blank surface water appeared to be 0.9911~0.9995 in the concentration range of 0.01~1.0 ng/mL. The limits of detection (LODs) and the limits of quantificaiton (LOQs) in spiked surface water were shown to be 0.0003~0.0234 ng/mL and 0.0046~0.0778 ng/mL, respectively. The developed method is believed to serve as a rapid and reliable method for the qualitative and quantitative analysis of residual ${\beta}$-lactam antibiotics from aquatic environment.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.27 no.2
• /
• pp.97-104
• /
• 1991

Generally, the coefficients of common holding power of an anchor and a chain cable have been reported too higher in their values in the safety of the shiphandling. The model experiment was carried out to find the most suitable coefficients of holding power of the Hall's type anchor and the chain cable in various kinds of seabed. The results obtained are summarized as follows; 1) The coefficients of holding power of the anchor and the chain cable were 4.05, 0.75 in the mud, 3.95, 0.66 in the sand and 3.61, 0.72 in the pebbles respectively. 2) The experimental coefficients of holding power of the anchor and the chain cable were 0.4~0.6 times the values of the coefficients of common holding power. They were almost same as the values of the coefficients of safe holding power in the mud and the sand, but in case of the pebbles, they were 1.4~1.8 times the values of the coefficients of safe holding power. 3) It is considered useful for the safety of the shiphandling to draw curves of the holding power with maximum limits holding power at the various wind forces and the coefficients of holding power.

• Journal of the Korean Chemical Society
• /
• v.39 no.12
• /
• pp.910-917
• /
• 1995

Analytical conditions for single column ion chromatographic determination of five anions such as F-, Cl-, NO2-, NO3-, and SO42- were optimized with respect to analysis time and separation efficiency. At the optimum condition of 2.0 mM phthalic acid at pH 4.5, five anions were effectively separated in 10 minutes so that analysis time could be reduced by 40% compared to other recommended conditions. Under this condition all the calibration curves of five anions were linear with a correlation coefficient > 0.999. Analytical results for nine commercial bottled waters were presented.

• Journal of Korea Water Resources Association
• /
• v.44 no.6
• /
• pp.487-495
• /
• 2011

The sampling and measuring methods of root fiber quantity which greatly governs the stability evaluation of a vegetated levee revetment are proposed by this study and the erosion characteristics related to root fiber quantity are analysed by the experiments. The Phragmites Japonica Steud confirmed the dominant species in a vegetated levee revetment and the Zoysinagrass are selected as the experimental vegetations. The characteristics of erosion depth and erosion rate are analysed according to the root fiber quantity and their corresponding regression equations are suggested. The erosion depth and erosion rate highly decrease with root fiber quantity by experimental results which results in great increasing the erosion resistance of a vegetated levee revetment. The corresponding regression equations for both vegetations of the Phragmites Japonica Steud and the Zoysinagrass are suggested with high determination coefficients. The erosion resistance of the Zoysinagrass is better than that of the Phragmites Japonica Steud.

• Analytical Science and Technology
• /
• v.7 no.4
• /
• pp.435-440
• /
• 1994

Qualitative and quantitative analysis for the anionic surfactants used in the metal washing fluid (brand names are BFA and BCA) was performed by the capillary electrophoresis. Acetonitrile and sodium benzoate were mixed with the buffer solution which controlled at pH 10. Under the 18kV applied voltage, the electropherograms have shown the theoretical plates more than $10^4$. Determined as the concentration at the S/N~3, the typical detection limit was ~5 ppm and the calibration curves have shown the correlation coefficients higher than ~0.99. Based on these results, it was concluded that each components were octanoate, decanoate, dodecanoate, tetradecanoate, hexadecanoate and the relative ratio was 1.0 : 1.0 : 6.5 : 2.1 : 0.8 for the BFA.

• Applied Chemistry for Engineering
• /
• v.9 no.5
• /
• pp.749-753
• /
• 1998

Methoxy polyoxyethylene dodecanoates, kinds of nonionic surfactants, could be obtained from addition of ethylene oxide (5, 7, 9, and 12mol) with fatty acid methyl ester utilizing solid catalyst, metal oxide. Because ethylene oxide (EO) couldn't react directly in acid or alkali catalyst with dodecanoic acid methyl ester (DME) that had no active hydrogen, the reaction to add EO was carried out using active solid catalyst. By using IR, HPLC and $^1H$ NMR analysis, structural confirmation of methyl polyoxy ethylene dodecanate showed high yield ranging from 93 to 97%. EO unit mol number of reacted products was 5.2, 7.1, 9.2 and 12.1 mol respectively. Also, EO adduct distrobution of ethoxylated methyl laurate (MPD) had normal distribution curve like polyoxyethylene alkyl ether (AE).

• Korean Journal of Food Science and Technology
• /
• v.7 no.3
• /
• pp.148-153
• /
• 1975

Seven toxigenic molds isolated from deteriorated rice in Korea, Aspergillus clavatus, Asp. flavus var. columnaris, Asp. fumigatus, Asp. ochraceus, Penicillium citrinum, Pen. implicatum, and Pen. islandicum, were examined for their sensitivity toward Co-60 gamma rays for survival. Conidia of all tested species showed survival curves of sigmoidal type, from which decimal reduction doses were found to vary in the range of $14{\sim}33$ krad, induction doses, in the range of $12{\sim}56$ krad and inactivation factors at 200 krad, in the range of $4.6{\sim}12.8$, all at a dose rate of 11.56 krad/min. Dose rate effects on the radiosensitivity of Asp. flavus and Pen. islandicum conidia indicated that the higher dose rate (11.56 krad/min) caused decreases in decimal reduction doses as compared with the lower dose rate (2.67 krad/min).