• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.9
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• pp.720-725
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• 2001

In this study, Pb(La,Ce)Ti $O_3$ ceramics were manufactured for 20 MHz resonator application. Electromechanical coupling factor( $k_{t}$, $k_{t3}$, mechanical quality factor( $Q_{mt}$ , $Q_{mt3}$ and dydnamic range (D.R) of thickness vibration mode were measured as the variations of $\ell$/t(length/thickness) ratio of ceramic substrates. Mechanical quality factor( $Q_{mt3}$) and dynamic range of third overtone thickness vibration mode showed the highest value of 2,773 and 52.22dB at specimen S4($\ell$/t=12), respectively. The excellent temperature stability of resonant frequency suitable for resonator application was shown, regardless of thermal shock.k.ock.k.

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.109-115
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• 2021

This study is a study on the difference in dose according to the presence or absence of gonadal shielding of scattered rays generated during chest computed tomography examination, and the scattered dose of the examination site was measured by placing the RadEye G-10 device in the center of the phantom. When the gonads are not shielded, the scattering lines of the whole, both sides, posterior and gonads are measured and Xenolite nolead Apron (0.35 mm PB), Xenolite nolead Apron (front 0.35 mm PB Mix back 0.25 mm PB, Skirt overlap), Half Apron After shielding with (0.5 mm PB), each scattered dose was measured. During chest computed tomography, the scattered dose of the test site was measured at 272 μSv, and when not shielded with Apron, the average total was 43 μSv, left 81 μSv, right part 82 μSv, posterior part 38.8 μSv, and Gonad part 16 μSv. Became. Xenolite nolead Apron shielded only the upper part and measured all 11.2 μSv, left part 43.1 μSv, right part 45.3 μSv, posterior part 12 μSv and Gonad part 5.2 μSv. Xenolite nolead Apron (Skirt overlap) covered the Pelvis area 360° and the dose was measured to be 5.6 μSv in the whole, 22.4 μSv in the left, 15.7 μSv in the right side, 6 μSv in the posterior part, and 3.2 μSv in the Gonad part. Xenolite nolead Apron (Skirt overlap) covered the Pelvis area 360° and the dose was measured to be 5.6 μSv in the whole, 22.4 μSv in the left, 15.7 μSv in the right side, 6 μSv in the posterior part, and 3.2 μSv in the Gonad part. When measuring only the upper part with Half Apron, the total measurement was 10.7 μSv, the left part 42.6 μSv, the right part 40.6 μSv, the posterior part 11.3 μSv, and the Gonad part 4.7 μSv. The method of 360° shielding of the pelvic area showed a dose reduction of more than 80%, and a dose reduction effect of more than 70% was shown when all shielding was performed. In all computerized tomography examinations, research to reduce the exposure dose and various shielding devices were used. It is believed that continuous research on the technique is needed.

• Biomolecules & Therapeutics
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• v.29 no.4
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• pp.384-391
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• 2021

Currently, the expanding recreational use of synthetic cannabinoids (SCBs) threatens public health. SCBs produce psychoactive effects similar to those of tetrahydrocannabinol, the main component of cannabis, and additionally induce unexpected pharmacological side effects. SCBs are falsely advertised as legal and safe, but in reality, SCB abuse has been reported to cause acute intoxication and addictive disorders. However, because of the lack of scientific evidence to elucidate their dangerous pharmacological effects, SCBs are weakly regulated and continue to circulate in illegal drug markets. In the present study, the intravenous self-administration (IVSA) paradigm was used to evaluate the abuse potential of three SCBs (AM-1248, CB-13, and PB-22) in rats. All three SCBs maintained IVSA with a large number of infusions and active lever presses, demonstrating their reinforcing effects. The increase of active lever presses was particularly significant during the early IVSA sessions, indicating the reinforcement-enhancing effects of the SCBs (AM-1248 and CB-13). The number of inactive lever presses was significantly higher in the SCB groups (AM-1248 and CB-13) than that in the vehicle group, indicating their impulsive effects. In summary, these results demonstrated that SCBs have distinct pharmacological properties and abuse potential.

• The Korean Journal of Ecology
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• v.13 no.3
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• pp.165-172
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• 1990

The contents of Pb and Cd in litters of Ginko biloba collected from thirty-four areas in Seoul were measured and analyzed for among relative air pollutions. S contents in litters of G. biloba were 0.88% at Hyehwadong, 0.98% at Yongsan and 0.95% at Ch angdong. Mean value were 0.65% in 0-10 km areas from Kwanghwamun, but were 0.47% in 10-15 km areas. In S contents, the correlation between 0-5 km area and 10-15 km area from Kwanghwamun was high significant, but correlation between 0-5 km area and 5-10 km area from Kwanghwamun had no significance. Pb contents were 118.95 ppm at Pildong, 112.22 ppm at Ulchiro 3-ga and 105.55 ppm at Bus terminal (Banpo). In Pb contents the correlation between 0-5 km area and 10-15 km aea from kwanghwamun was high significant, but the correlation between 0-5 km area and 5-10 km area from Kwanghwamun had no significance. In Cd contents. Cd contents were high in Youido, Shinch on, Kongdokdong, Haengdangdong, Kirum, Ch ongnyangni and Imundong.

• Journal of the Korean Applied Science and Technology
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• v.30 no.3
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• pp.551-559
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• 2013

To investigate the adhesion effect of sodium bisulfite content in making blocked isocyanate, wood adhesive PB-1, PB-2, PB-3 and PB-4 containing sodium bisulfite content of 15%, 22.5%, 30% and 37.5% were synthesized respectively. As a result, when the amount of sodium bisulfite increased in adhesives, the tensile strength was found to be proportionally increased. The final adhesive mixtures were manufactured using a two-components system which are prepared by mixing two separate protein and BI solutions due to the precipitate in the adhesives. As PVA was added to adhesives to increase tenacity, the plywood dehiscence phenomenon after cold pressing process was declined. By addition of PVA, the tensile strength was improved up to $6.5{\sim}7kgf/cm^2$ with BI/protein ratio from 1:6 up to 1:8. Phase separation between milk fat and aqueous layer was disappeared after addition of emulsifier, Tween 20. Additon of Tween 20 showed tensile strength up to $5{\sim}6.5 kgf/cm^2$ at NCO/protein ratio of 1:12 ~ 1:14 without phase separation.

• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.871-878
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• 2006

Batch experiments were performed to evaluate the applicability of soil washing for heavy metal contaminated soils at Nacdong and Hamchang abandoned mines. The texture of the Nacdong soil was sandy loam. Nacdong abandoned mine soil was almost neutral (pH=6.5). Contaminations of As, Cd, Pb and Zn for Nacdong mine soils were 12,900 mg/kg, 29 mg/kg, 696 mg/kg and 276 mg/kg, respectively. Hamchang abandoned mine soils were acidic (pH=2.6) and the soil texture was loam. The contaminations of As, Cd, Pb and Zn for Hamchang abandoned mine soils were 6,410 mg/kg, 291 mg/kg, 1,300 mg/kg and 1,110 mg/kg, respectively. For the Nacdong abandoned mine soils, oxalic acid was found to be the most effective soil washing extracter for As and Pb while citric acid was the most effective extracter for Cd. For the Hamchang abandoned mine soils, oxalic acid showed the highest extraction efficiencies for As and Pb, whilst citric acid presented the best soil washing efficiencie for Cd. Oxalic acid and EDTA were found to be the most effective soil washing extracter for the Hamchang abandoned mine contaminated soils.

• Journal of the Korean Physical Society
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• v.73 no.9
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• pp.1370-1376
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• 2018

The electronic structures, magnetic properties and half-metallicity in $Zr_2RuZ$ (Z = Ga, In, Tl, Ge, Sn, and Pb) alloys with $AlCu_2Mn-$ and $CuHg_2Ti$-type structures were investigated using first-principles density functional theory (DFT) calculations. The calculations showed that $Zr_2RuIn$, $Zr_2RuTl$, $Zr_2RuSn$, and $Zr_2RuPb$ compounds with $CuHg_2Ti$-type structures were half-metallic ferromagnets with half-metallic band gaps of 0.18, 0.24, 0.22, and 0.27 eV, respectively. The half-metallicity originated from d-d and covalent hybridizations between the transition metals Zr and Ru. The total magnetic moments of the $Zr_2RuZ$ (Z = In, Tl, Sn, and Pb) compounds with $CuHg_2Ti$-type structures were integer values of $1{\mu}B$ and $2{\mu}B$, which is in agreement with Slater-Pauling rule ($M_{tot}=Z_{tot}-18$). Among these compounds, $Zr_2RuIn$ and $Zr_2RuTl$ were half-metals over relatively wide regions of the lattice constants, indicating that these two new Heusler alloys are ideal candidates for use in spintronic devices.

• Analytical Science and Technology
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• v.22 no.3
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• pp.201-209
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• 2009

Four heavy metals (Pb, Cd, As, and Hg) in 38 species (total 325 samples) of oriental animality medicines were monitored by inductively coupled plasma-mass spectrometry (ICP-MS) and automatic mercury analyzer (AMA). The detected concentration range of Pb, Cd, As was presented as $0.02{\mu}gkg^{-1}$ $(D.L){\sim}11.29mgkg^{-1}$, $0.01{\mu}gkg^{-1}$ $(D.L){\sim}2.50 mgkg^{-1}$, $0.12{\mu}gkg^{-1}$ $(D.L){\sim}5.27mgkg^{-1}$, respectively. In case of Hg, it the concentration range was $0.01{\sim}77.11mgkg^{-1}$ except one sample which exceeded detection limit. In all samples of Amydae Carapax and Gallnut, it was not detected over the maximum residue limits of metals. Pb is in charge of the greatest portion of contamination in 22 species of animality medicines, and in case of Hg, 54.46% of total samples were over the maximum residue limits. Therefore, environmental levels of Pb and Hg are needed to continue the researches and the studies for tracking pollution source are required.

• Journal of Soil and Groundwater Environment
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• v.12 no.3
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• pp.17-22
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• 2007

The feasibility of soil washing was investigated to remediate Pb-contaminated field soil. Hydrochloric acid was used as a washing agent. As mixing time increased from 5 min to 120 min, removal efficiency of Pb from contaminated soil increased from 69.3% to 81.9%. Two times washing with 0.2 M HCl showed 96% removal efficiency even at mixing time of 10 min. The Pb content in soil increased sharply as particle size of soil decreased, and removal efficiency was highly dependent on mixing time and temperature. Based on this result, acid washing technologies can be applied to remediate the Pb-contaminated soil used in this study.

• Journal of Environmental Science International
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• v.15 no.2
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• pp.163-167
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• 2006

To obtain the safety evaluation of the ginseng, residues of heavy metals in culture environment of ginseng on Punggi and Sangju, Kyeongbuk are surveyed. The concentration for component of ginseng on Punggi and Sangju were 14.12mg/kg and 15.74mg/kg, respectively. The concentration for general component such as crude fiber, ash, crude lipid, crude protein, carbohydrate, of ginseng were coincided between Punggi and Sangju. The concentration for As, Pb, Cd, and Hg in soil on Punggi were 14.24 ppb, 43.13 ppb, 8.73 ppb and 0.82 ppb, respectively. The concentration for As, Pb, Cd, and Hg in soil on Sangju were 19.20 ppb, 54.82 ppb, 15.90 ppb and 1.04, respectively. Residual heavy metals are not polluted in the soil with culture ginseng on Punggi and Sangju. The concentration for As, Pb, Cd, and Hg with ginseng on Punggi were 29.30ppb, 21.78 ppb, 1.32 ppb and 2.72 ppb, respectively. The concentration for As, Pb, Cd, and Hg with ginseng on Sangju were 3.22 ppb, 24.43 ppb, 1.44 ppb and 4.74 ppb, respectively. Also the detection concentration for As, Pb, Cd, and Hg in ginseng were also lower than the Korea Food & Drug Administration advisory level for heavy metal in herbal medicines. Residual heavy metals are not polluted in the ginseng on Punggi and Sangju at Kyeongbuk, Korea.