• 대한약침학회지
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• 제10권1호통권22호
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• pp.67-77
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• 2007

Objectives : Heavy metal contents in cultivated wild ginseng from Korea and China were evaluated for the safety purpose. Methods : Arsenic(As), cadmium(Cd), lead(Pb), mercury(Hg), copper(Cu), chromium(Cr), and selenium(Se) from the root, stem, and leaves of the Korean cultivated wild ginseng and the root of the Chinese cultivated wild ginseng were analyzed for the existence of heavy metal contents. Results : Most of heavy metals weren't detected in all the samples. Copper and lead were found in very minute volume and didn't reach the toxic concentration level of 10mg/kg. Samples used in the test were grown in non-contaminated areas, free from heavy metal contamination. Conclusions : Based on above results, cultivated wild ginseng from Korea and China are relatively safe from the heavy metal exposure. But for more rigorous quality control, an epidemiological survey using the samples from more diverse areas should be conducted.

• Advances in materials Research
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• 제4권3호
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• pp.165-178
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• 2015

Friction coefficient of epoxy metal matrix composites were investigated. The main objective was to increase the friction coefficient through rubber sole sliding against the epoxy floor coating providing appropriate level of resistance. This was to avoid the excessive movement and slip accidents. Epoxy metal matrix composites were reinforced by different copper wire diameters. The epoxy metal matrix composites were experimentally conducted at different conditions namely dry, water and detergent wetted sliding, were the friction coefficient increased as the number of wires increased. When the wires were closer to the sliding surface, the friction coefficient was found to increase. The friction coefficient was found to increase with the increase of the copper wire diameter in epoxy metal matrix composites. This behavior was attributed to the fact that as the diameter and the number of wires increased, the intensity of the electric field, generated from electric static charge increased causing an adhesion increase between the two sliding surfaces. At water wetted sliding conditions, the effect of changing number of wires on friction coefficient was less than the effect of wire diameter. The presence of water and detergent on the sliding surfaces decreased friction coefficient compared to the dry sliding. When the surfaces were detergent wetted, the friction coefficient values were found to be lower than that observed when sliding in water or dry condition.

• 생태와환경
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• 제40권4호
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• pp.489-494
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• 2007

Transcriptional modulation of metallothionein (MT) during acute metal exposures (cadmium, copper or zinc) was examined in fry of Hemibarbus mylodon, a threatened fish species in Korean peninsula. Viability of H. mylodon fry was most affected by copper exposure (up to 79% of mortality at 1 ppm for 48 hours) and considerably by cadmium exposure (21 to 54% of mortality). On the other hand, Zn showed the least adverse effect on the viability (0 to 13% of mortality) of this species. Based on the semi-quantitative RT-PCR analysis, the stimulation of MT mRNA in response to metal exposures followed generally in a dose-dependent fashion where cadmium was the most potent inducer for the induction of MT transcripts in fry (up to more than 5-fold) while the lowest response was observed in zinc-exposed group (2-fold at maximum). From the exposure using environmentally realistic doses of cadmium (0 to 0.05 ppm for 24 hours), MT expression at mRNA level was also sensitively modulated toward upregulation up to more than 3-fold as relative to non-exposed control. Results from the present study would be a good basis for understanding the adaptive capacity and stress physiology of this endangered fish species during metal pollution.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.529-531
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• 2003

In order to investigate the level of heavy metal contamination and the seasonal variation of metal concentrations in soils and sediments influenced by past mining activities, tailings, soil and sediment samples were collected from the Hwacheon mine in Korea. The main pollution sources in this mine site are suggested as tailings and mine waste rocks. Elevated levels of Cd, Pb and Zn were found in soils and sediments. In a study of seasonal variation on the heavy metals in soils and sediments, heavy metals were higher enriched collected from before rainy season ($2^{nd}$ sampling) than after rainy season ($1^{st}$ sampling). Also, in order to estimate the microbial effects on Cd speciation in sediments, bacteria which can adsorb Cd was isolated and Cd adsorption characteristics of isolated bacteria in Cd solution was evaluated. The Cd bioremoval efficiency in Cd solution (5 ppm) by bacteria was more than $90\%$. Bioremoval efficiency in single metal solution was higher than that in mixed metal solution of Pb and Zn.

• 한국식품영양학회지
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• 제15권1호
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• pp.64-69
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• 2002

To know a degree of pollution in agricultural products cultivated around 4 unworked mines located in Chollanam-Do, we investigated a concentration of heavy metal and trace metal to provide the basic data for its residual limits. 28 samples of seven kinds of agricultural products(lettuce, onion, potato, radish, pepper, pumpkin, bean) collected from 4 unworked mines located in Chollanam-Do in 2001 were analyzed by Mercury Analyzer for mercury and Atomic Absorption spectrophotometer for Pb, As, Cd, Cu, Mn, and Zn. Hg contents were detected N.D. ∼trace level(0.01 ppm and less) and As content were detected N.D. ∼ 0.029 lpm but most of same)leE were not detected. Cd contents were detected N.D∼0.124 ppm. The results of Hg, As, Pb and Cd content showed that for all the 7 species of agricultural products studied, none have accumulated levels dangerous enough to Pose health problems. The average contents of Cu were 3.070 ∼ 7.825 ppm in bean, the Mn were 3.688 ∼23.935 ppm in lettuce ailed the Zn were 5.690 ∼21.171 ppm in bean, respectively.

• 한국분무공학회지
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• 제11권2호
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• pp.59-68
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• 2006

Experimental results of the metal powder production with internal mixing, internal impinging and the atomizer coupled with substrate design are presented in this paper. In a test with internal mixing atomizer, mean powder size was decreased from $37{\mu}m\;to\;23{\mu}m$ for Pb65Sn35 alloy as the gas-to-melt mass ratio was increased from 0.04 to 0.17. The particle size further reduces to $16.01{\mu}m$ as the orifice area is increased to $24mm^2$. The micrograph of the metal powder indicates that very fine and spherical metal powder has been produced by this process. In a test program using the internal impinging atomizers, the mean particle size of the metal powder was decreased from $22{\mu}m\;to\;12{\mu}m$ as the gas-to-melt-mass ratio increased from 0.05 to 0.22. The test results of an atomizer coupled with a substrate indicates that the deposition rate of the molten spray on the substrate is controlled by the diameter of the substrate, the height of the substrate ring and the distance of the substrate from the outlet of the atomizer. This in rum determines the powder production rate of the spraying processes. Experimental results indicate that the deposition rate of the spray forming material decreases as the distance between the substrate and the atomizer increases. For example, the deposition rate decreases from 48% to 19% as the substrate is placed at a distance from 20cm to 40cm. On the other hand, the metal powder production rate and its particle size increases as the subsrate is placed far away from the atomizer. The production of metal powder with mean particle size as low as $3.13{\mu}m$ has been achieved, a level which is not achievable by the conventional gas atomization processes.

• Clinical and Experimental Reproductive Medicine
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• 제24권1호
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• pp.67-81
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• 1997

To determine the concentration and the physiologic role of metal components in blood plasma and seminal plasma in relation to male infertility, the concentrations of twelve metal components in blood plasma and seminal plasma including Na, Mg, K, Ca, Cr, Mn, Fe, Cu, Zn, Se, Cd and Pb were measured by atomic absorbance spectrophotometery or ion selective electrode analysis. Semen and blood samples were obtained from a total of 110 men including 70 male infertility patients, 20 vasectomized persons and 20 fertility proven volunteers visited to the Male Infertility Clinic of Pusan National University Hospital. The concentrations of Ca, Zn, Mg, Cr and Cd in control group were higher in seminal plasma than in blood plasma, and additionally Pb were higher in infertility group. The concentrations of all metal components revealed no significant difference according to patients' age, resident, occupation, sperm density, motility and hormone level in blood plasma, but some metal components including Ca, Mg, Cu, Mn, Cd and Pb revealed a significant difference according to each these parameters except patient's age in seminal plasma. The concentrations of Mn, Cd and Pb in the vasectomy persons were higher than in the infertility group III including testicular and epididymal factors, but not in blood plasma. We conclude that the quantitative changes of metal components in the seminal plasma may have effects on not only spermatogenesis and sperm function, but also contribute to diagnostic parameter according to organ specificity of the metal in the male reproduction.

• 생명과학회지
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• 제19권11호
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• pp.1562-1567
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• 2009

안동호와 임하호의 수환경내 중금속의 오염정도와 서식 어종간의 중금속 축적 정도를 알아보기 위해 양호수의 수질, 저니 및 서식어종인 붕어를 이용하여 중금속 함량을 비교 분석하였다. 안동호와 임하호 수질과 저니내 중금속 함량은 안동호에서 높은 함량을 보이며, As는 함량의 차이가 큰 것으로 나타났다. 안동호와 임하호에 서식하는 붕어의 중금속 함량의 경우 안동호에 서식하는 붕어에서 높은 함량을 보이며, Cr, Cu, Cd 및 As는 함량의 차이가 큰 것으로 나타났다. 또한 비늘, 근육, 뼈 조직은 안동호와 임하호의 함량차이가 크며, 안동호에서 높은 함량을 나타냈다. 본 연구의 결과 안동호와 임하호의 수질과 저니 및 서식어종인 붕어의 중금속 함량은 안동호에서 임하호보다 중금속 함량이 높게 나타났으며, 안동호와 임하호의 함량차이도 큰 것으로 나타났다. 이는 안동호의 경우 안동호 상류 지점의 폐광산과 농경지로부터 하상퇴적물이 유입되어 하상퇴적물 속에 포함된 유기물을 붕어가 먹이로 섭취함으로써 중금속 함량에 영향을 미친 것으로 생각된다.

• 대한치과보철학회지
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• 제45권6호
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• pp.805-814
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• 2007

Statement of problem. Composite resin-veneered metal restorations can be used as an alternative to porcelain-fused-metal restorations. But, because of the relatively low bond strength of veneering composite to metal framework, various surface treatment methods have been introduced to improve the bond strength. Purpose. The object of this study was to compare the shear bond strength of different combinations of each of the two bonding systems and each of the two composite veneering resins to cp-Ti/Co-Cr alloy. Material and methods. Two resin bonding systems (metal conditioner containing MEPS monomer, tribochemical silicoating system) and two composite resins (Gradia, Sinfony) were tested on cp-Ti and Co-Cr alloy. Then, according to manufacturers' instructions, resin bonding systems and composite resins were applied. All test specimens were divided into four groups for each alloy; I) sandblast + Metal Primer II + Gradia (MG), II) sandblast + Metal Primer II + Sinfony (MS), III) Rocatec + Gradia (RG), IV) Rocatec + Sinfony (RS). The shear bond strength was determined using a universal testing machine and all data were statistically analyzed with Mann-Whitney test and Kruskal-Wallis test at the significance level of 0.05. Results. The mean (standard deviations) of shear bond strength according to the combinations of two bonding systems and two composite resins to cp-Ti arranged from 16.44 MPa to 17.07 MPa and the shear bond strength to Co-Cr alloy ranged from 16.26 MPa to 17.70 MPa. The result shows that the difference were not statistically significant. Conclusion. The shear bond strengths of composite resins to both cast cp-Ti and Co-Cr alloy were not significantly different between the metal conditioner and the tribochemical silicoating system. And no differences in bond strength were found between cp-Ti and Co-Cr alloy.

• 한국환경보건학회지
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• 제45권3호
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• pp.258-266
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• 2019

Objectives: In this study, blood lead was analyzed using graphite furnace atomic absorption spectrometry (GF-AAs) and inductively coupled plasma mass spectrometry (ICP-MS). We tried to examine the difference and consistency of the analytical values and the applicability of the analytical method. Methods: We selected 57 people who agreed to participate in this study. After confirming the linearity of the calibration standard curves in GF-AAs and ICP-MS, the concentrations of lead in quality control material and samples were measured, and the degree of agreement was compared. Results: The detection limit of the ICP-MS was lower than that of GF-AAs. The coefficient of variation of reference materials was shown to be stable in the ICP-MS and GF-AAs. When the correspondence between the two equipments was verified by bias of the analysis values, a concordance was shown, and approximately 98% of the ideal reference lines were present within ${\pm}40%$ of the deflection. Conclusion: GF-AAs showed high sensitivity to single heavy metal analysis, but it took much time and showed higher detection limit than ICP-MS. Therefore, it would be considered necessary to switch to ICP-MS analysis method, considering that the level of lead exposure is gradually decreasing.