• 생약학회지
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• 제22권1호
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• pp.33-35
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• 1991

Heavy metals may cause trouble(s) in human body. For consideration of the safety of crude drugs cultivated in Korea, we selected some medicinal plants and soils from cultivated site and estimated their heavy metal contents by inductively coupled argon plasma spectrometry (ICAP). Among heavy metals tested, the highest level of Cu and Zn were shown in plants cultivated in Kyung Ki; the highest level of Fe in those in Youngnam and the highest level of Mg and Mn in those in Youngdong. The heavy metal content s were as low as to be permeasible at least for the medicinal plants we selected. There were no significant correlations between heavy metal contents of soils and cultivated medicinal plants.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2004년도 추계학술발표대회 개요집
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• pp.123-124
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• 2004

This study was investigated on the impact toughness and microstructure of welded metal and heat affected zone for Hi Nitrogen TiN Steel. With welding procedures, welding heat input applied were 30, 79 and 264 kJ/cm. TiN steel has shown very small prior austenite grain size for all the welding heat input applied, which was considered to result from the effect of TiN particles. In case of single SAW and EGW welding, the dilution rate of base metal into the weld was not high, resulting that there were no significant effects of base metal chemical composition on the mechanical properties of welds. However, TSAW with double Ypreparation carried very high dilution rate so that TiN steel has impaired the toughness of weld metal because N content in the weld was increased through the dilution of base metal.

• 통합자연과학논문집
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• 제6권3호
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• pp.151-157
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• 2013

The ion exchange resins were synthesized from 1-aza-18-crown-6 macrocyclic ligand attached to styrene (2th petroleum in 4th class hazardous material) divinylbenzene (DVB) copolymer with crosslinks of 1%, 6%, and 15% by substitution reaction. These synthetic resins were confirmed by chlorine content, elementary analysis, surface area, and IR-spectrum. The object of this study was to seperate the metal ion absorbed in reinforcement water fire extinguishing agent. As the results of the effects of pH, equilibrium arrival time, and crosslink of synthetic resin on metal ion adsorption for resin adsorbent, the metal ions were showed high adsorption at pH 3 or over and adsorption equilibrium of metal ions was about 2 hours. In addition, adsorption selectivity for the resin in water was the order of Al (III) > Ni (II) > Sm (III) ions, adsorbability of the metal ions was in the crosslinks order of 1%, 6%, and 15%.

• 한국세라믹학회지
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• 제22권3호
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• pp.29-34
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• 1985

The IR spectra of he heavy metal fluoride glasses showed peaks at $1, 400cm^{-1}$ or $1, 100cm^{-1}$ due to metal oxyfluoride impurities. The intensity of this band and hence the oxide impurity content of the glass could be reduced considerably by the use of reactive atmosphere melting under $CCl_4$ In comparison with the fundamental IR absorption band of heavy metal oxides the oxide impurity bands observed in the heavy metal fluoride glasses are multiphonon bands due to a 2-phonon absorption process. The envelope of the a vs. v curve beyond thue fundamental region shows the exponential fall off of a with increasing v-typical of intrinsic multiphonon absorption. In the multiphonon region the amount of structure is intermediate between that observed for covalent solids and that for ionic solids.

• 통합자연과학논문집
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• 제10권1호
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• pp.43-50
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• 2017

Synthetic resins were combined 1-aza-12-crown-4 macrocyclic ligand with styrene divinylbenzene copolymer having 1%, 2%, 8%, and 16% crosslink by a substitution reaction. These synthetic resins were confirmed by chlorine content, elementary analysis, SEM, surface area, and IR-spectrum. As the results of the effects of pH, crosslink of synthetic resin, and dielectric constant of a solvent on metal ion adsorption for resin adsorbent, the metal ions showed high adsorption at pH 3 or over. Adsorption selectivity for the resin in ethanol solvent was the order of uranium ($UO_2{^{2+}}$) > cobalt ($Co^{2+}$) > dysprosium ($Dy^{3+}$) ion, adsorbability of the metal ion was the crosslink in order of 1%, 2%, 8%, and 16% and it was increased with the lower dielectric constant. In addition, theses metal ions could be separated in the column with 1% crosslink resin by using nitric acid (pH 2.0) as an eluent.

• 대한금속재료학회지
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• 제47권9호
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• pp.550-557
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• 2009

In this study, bronze or SUS304 powders blended with 10 wt.% diamond particles were used to prepare metal/diamond composite materials deposited by cold spraying. The effects of matrix metal, diamond partical size, and the thickness of the Ni coating on the diamond were studied on Al 6061 substrate. The results showed that the hardness of the metal/diamond composite coating layers was higher than that of the same composite materials when using the sintering method. The fraction of diamond content in the coated layer increased when the metal matrix was soft. When the size of the diamond particles was reduced, the fraction of the diamond particles increased. In addition, in the case of diamond with a thicker Ni-coated layer, the fracturing of diamonds was mitigated in the composite coating layers.

• Journal of Preventive Medicine and Public Health
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• 제21권1호
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• pp.121-131
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• 1988

This study was performed to investigate the heavy metal contents of freshwater fishes. The samples of 24 species were collected at 7 areas located on the Mankyung River during September in 1987. And then the contents of lead, cadmium, copper and zine were analyzed by atomic absorption spectrophotometer. The results were summarized as follows ; 1. The mean value of lead, cadmium, and copper contents of fishes collected in the downstream were significantly higher than those of upstream. 2. The mean lead content of C. auratus was the highest $1.50{\pm}0.98{\mu}g/g$ in viscera and statistically significant difference from muscle content. 3. The mean cadmium content of C. auratus was the highest $0.087{\pm}0.054{\mu}g/g$ in viscera and significantly higher than that of muscle. 4. In the copper contents, the viscera of C. auratus was the highest $5.25{\pm}0.94{\mu}g/g$ and significantly higher than that of muscle, skeleton and gill. 5. The mean value of zinc content of C. auratus was shown the order of gill, skeleton, viscera and muscle.

• 동력기계공학회지
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• 제9권4호
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• pp.130-136
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• 2005

The effects of additional Mg content, the size and volume fraction of reinforcement phase on the mechanical properties of ceramic particle reinforced aluminium matrix composites fabricated by pressureless metal infiltration process were investigated. The hardness of $SiC_p/AC8A$ composites increased gradually with an increase in the additive Mg content, while the bending strength of $SiC_p/AC8A$ composites increased with an increase in additive Mg content up to 5%. However, this decreased when the level of additive Mg content was greater than 5% due to the formation of coarse precipitates by excessive Mg reaction and an increase in the porosity level. The hardness and strength of the composites increased with decreasing the size of SiC particle. It was found that the composites with smaller particles enhanced the interfacial bonding than those with bigger particles from fractography of the composites. The hardness of $Al_2O_{3p}/AC8A$ composites increased gradually with an increase in the volume fraction, however, the bending strength of $Al_2O_{3p}/AC8A$ composites decreased when the volume fraction of alumina particle was greater than 40% owing to the high porosity level.

• Smart Structures and Systems
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• 제5권3호
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• pp.209-221
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• 2009

A control algorithm for seismic protection of building structures based on the theory of variable structural control or sliding mode control is presented. The paper focus in the design of sliding surface. A method for determining the sliding surface by pole assignment algorithm where the poles of the system in the sliding surface are obtained on-line, based on the frequency content of the incoming earthquake signal applied to the structure, is proposed. The proposed algorithm consists of the following steps: (i) On-line FFT process is applied to the incoming part of the signal and its frequency content is recognized. (ii) A transformation of the frequency content to the complex plane is performed and the desired location of poles of the controlled structure on the sliding surface is estimated. (iii) Based on the estimated poles the sliding surface is obtained. (iv) Then, the control force which will drive the response trajectory into the estimated sliding surface and force it to stay there all the subsequent time is obtained using Lyapunov stability theory. The above steps are repeated continuously for the entire duration of the incoming earthquake. The potential applications and the effectiveness of the improved control algorithm are demonstrated by numerical examples. The simulation results indicate that the response of a structure is reduced significantly compared to the response of the uncontrolled structure, while the required control demand is achievable.

• 한국농공학회논문집
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• 제48권1호
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• pp.3-10
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• 2006

The chemical fractions of heavy metals were investigated in the soils of reclaimed and natural tidelands of southwest coastal area of Korea. The distribution pattern of each heavy metal in different fractions was in the order: 1) Cu : organic bound > organic complex > residual > exchangeable = water soluble. 2) Cr : residual > organic bound > organic complex > water soluble > exchangeable. 3) Pb : organic bound > residual > organic complex > water soluble > exchangeable. 4) Cd residual > organic bound > organic complex > water soluble = exchangeable. 5) Zn : organic bound > residual > organic complex > water soluble > exchangeable. The content of residual Zn showed positive correlation with organic matter content but organic bound Zn showed negative correlation with CEC. The content of residual and exchangeable Cd showed highly positive correlation with organic matter content but residual, organic bound, and exchangeable Cd showed negative correlations with CEC. Water soluble Pb showed positive correlation with CEC but organic bound Pb showed negative correlation with CEC.