• 한국방사선학회논문지
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• 제16권4호
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• pp.381-386
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• 2022

비파괴검사(NDT; Non-Destruction Test)는 제품의 기능을 손상시키거나 물리적으로 파괴시키지 않고 내부의 결함을 검사하는 방법이다. 이러한 방사선투과검사는 고에너지의 방사선을 사용하기 때문에 방사선작업종사자들의 방사선피폭을 방지하는 것은 매우 중요하다. 이에 본 연구는 PbI₂에 Gd₂O₂S:Tb를 결합하여 기존 PbI₂보다 방사선 검출성능을 더욱 향상시켜 방사선투과검사에서 선원누출 등의 사고를 즉각적으로 감지할 수 있는 새로운 구조의 방사선 센서를 제시하였다. 평가는 FLUKA 전산 모사를 통하여 감마선원에서 Gd₂O₂S:Tb 결합 전후의 변환 효율을 분석하였다. Gd₂O₂S:Tb가 결합된 PbI₂는 방사선 검출성능이 1.22배에서 3.22배까지 더 높은 것으로 나타났다. 이러한 결과로부터 본 연구에서 제시된 센서는 방사선투과검사 선원 감지용 방사선 센서로 적용 가능할 것으로 분석되었다.

• 한국환경과학회지
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• 제27권6호
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• pp.401-410
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• 2018

Waste citrus peel-based activated carbon (WCAC) was prepared from waste citrus peels by activation with KOH. The removal of Cu and Pb ions from aqueous solution by the prepared WCAC was investigated in batch experiments. The solution pH significantly influenced Cu and Pb adsorption capacity and the optimum pH was 4 to 6. The adsorption of Cu and Pb ions by WCAC followed pseudo-second-order kinetics and the Langmuir isotherm model. The maximum adsorption capacity calculated by Langmuir isotherm model was 31.91 mg/g for Cu and 92.22 mg/g for Pb. As the temperature was increased from 303 K to 323 K, the ${\Delta}G^{\circ}$ value decreased from -7.01 to -8.57 kJ/mol for Cu ions and from -0.87 to -2.06 kJ/mol for Pb ions. These results indicated that the adsorption of Cu and Pb by WCAC is a spontaneous process.

• 상하수도학회지
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• 제22권2호
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• pp.251-257
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• 2008

Food compost, having a higher organic contents than soil, could be an alternative material to prevent the proliferation of heavy metals contamination in soil. In this study we used a convection-dispersion local equilibrium sorption model(CDE) and a two-site non-equilibrium sorption model to find the effects on the adsorption and transportation of Pb by mixing food compost with soil and we also tried to find the effect of velocity and concentration of the injected solution on the characteristics of Pb. We measured Pb concentrations in injection-liquid and in effluent, and then applied them to CXTFIT program. As a result of column experiments, some parameters(D, R, ${\beta}$, ${\omega}$) used in two-site non-equilibrium adsorption model were obtained. Characteristics of Pb adsorption and transport were analyzed using the parameters(D, R, ${\beta}$, ${\omega}$) obtained from the CXTFIT program, We could know that mixed soil with food compost showed a higher adsorption capacity from the retardation factor(R) calculated from the breakthrough curve(BTCs) of Pb. Rs of soil and mixed soil are 20.45, 37.45 respectively, indicating that the adsorption and the transportation characteristics could be accessed quantitatively by using of two-site non-equilibrium adsorption model.

• Journal of Welding and Joining
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• 제31권3호
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• pp.22-30
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• 2013

Due to ELV banning, automotive electronics cannot use four kinds of heavy metal element (Pb, Hg, Cd, $Cr^{6+}$) from 2016. Therefore, this study was focused on degradation characteristics of Sn-3.0Ag-0.5Cu Lead-free solder joint with OSP and ENIG finsh under various reliability assessment method, as like to thermal shock test and high temeprature/high humidity test with test duration for cabin electronics. Also, we compared bonding strength degradation to other advanced research results of electronic control unit for engine room because of difference service temperature with mount location in automotive. Whisker growth phenomenon and mitigation method which were essentially consideration items for Pb-free car electronics were examined. Conformal coating is a strong candidate for mitigating whisker growth in automotive electronics. Necessary condition to adapt Pb-free in car electronics was shown.

• 한국해양환경ㆍ에너지학회지
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• 제18권2호
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• pp.64-73
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• 2015

2009년 7월 3일부터 7월 27일까지 러시아 조사선 R/V Lavrentyev를 이용하여 러시아 연안으로부터 4개의 Line(D, R, E, A)을 따라 표층 30 m 수심의 시료를 26개 정점에서 채수하여 Pb와 Cd의 농도를 분석하였다. 해역별로 Pb와 Cd의 농도를 비교하면, 연안역에서는 러시아 연안(평균 Pb, 0.08; Cd, 0.10 nM )보다 우리나라 동해 연안의 농도(평균 Pb, 0.49; Cd, 0.11 nM)가 Pb의 경우 6.0배 높은 반면 Cd의 농도는 비슷하게 나타났으며, 난수역(평균 Pb, 0.22; Cd, 0.10 nM)은 냉수역(평균 Pb, 0.13; Cd, 0.14 nM)에 비해 Cd의 농도는 0.4배 낮은 반면, Pb의 농도는 약 1.7배 높게 나타났다. 또한 Pb와 Cd의 농도 분포는 표층 수온 $10^{\circ}C$를 기점으로 구분되는 특성을 보이고 있다. $10^{\circ}C$ 이하에서 수온이 감소함에 따라 농도가 증가하는 추세로 한류수의 농도가 주변 연안이나 외해의 해수보다 농도가 다소 높게 나타났으며, $10^{\circ}C$ 이상에서는 온도가 증가함에 따라 농도가 증가하는 추세로서 대마난류와 인접국가(우리나라와 일본)의 직접적인 영향권에 있는 울릉분지에서 높은 농도를 보이고 있다. 특히 Pb의 경우, 고온의 대마난류가 유입되는 정점 D10을 최고점으로 고위도로 북상할수록 수온의 감소와 더불어 농도의 감소 현상이 두드러지게 나타났으며, 서지중해와 동태평양의 측정치보다 다소 높게 나타나서 대만난류를 통한 유입량과 우리나라와 일본으로부터 대기를 통한 전달량의 영향이 상대적으로 클 것으로 추론할 수 있다. 따라서 동해 표층수의 Cd농도 분포는 주로 동해에 존재하는 다양한 수괴의 혼합에 의해 영향을 받는 반면, Pb은 대기와 대마난류를 통한 전달량에 의해 크게 영향을 받으며, 기타 강물을 통한 유입과 유,무기성 입자물질과의 상호작용에 의해 결정될 것이다.

• Journal of Nutrition and Health
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• 제22권3호
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• pp.185-193
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• 1989

This study was performed to investigate lead(Pb) detoxification with different dietary protein levels and detoxifying periods in Pb poisoned rats. Forty nine male rats of Sprague-Dawley strain weighing 114$\pm$4g were used and they were fed 1% Pb-15% casein diet ad libitum for 2 weeks. After sacrifying 7 animals as control group, remaining forty two rats were blocked into 6 groups according to body weight. Three groups were fed each detoxifying diet(5%, 15% or 40% casein diet without Pb) for 1 week and the other 3 groups were fed same diets for 3 weeks. The results obtained were summerized as follows ; 1) Liver and kidney weight, bone weight, and bone length were increased with increasing dietary protein level and detoxifying period. 2) Hematocrit values were recovered to normal level during detoxifiying periods but hemoglobin contents in detoxifying diet groups showed no significant difference from those in control group. 3)Pb contents in blood were decreased with increasing dietary protein level, and Pb contents in liver were significantly decreased in high protein diet groups. Pb contents in kidney were significantly decreased during detoxifying period compared to control group, but no significant difference was shown within the detoxifying diet groups. Pb contents in femur were significantly decreased after 3 weeks of detoxifying period but no difference was shown with different dietary protein level. 4) Urinary Pb excretions were significantly increased with increasing dietary protein level. Fecal Pb excretions were remarkably decreased after 3 weeks of detoxifying period, but no difference was showen in fecal Pb excretions with different dietary protein level. Above results suggest that high protein diet improves Pb detoxification by increasing urinary Pb excretion.

• 한국세라믹학회지
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• 제22권2호
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• pp.39-43
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• 1985

This study presents the results of an overall effort to detemine the applicability of the chemical wet process informing lead titanate electronic ceramics. Although pure lead titanate has not proven to be an important technological materials when prepared via conventional processing procedures this work is interesting as a study of chemical wet processing and a way of preparing pbTiO3 for study. The result obtained from this experiment were as follows ; Optimum synthesis condition which synthesize PbTiO3 by chemical wet process was obtained by firing at 50$0^{\circ}C$ after mixing $Pb(OH)_2$- gel and $Ti(OH)_4$ -gel at 7$0^{\circ}C$ for 4 hours.

• Journal of Plant Biology
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• 제22권4호
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• pp.107-113
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• 1979

The present study was carried out to estimate the comparative effects of hydroponic heavy metals (Al, Cd, Hg, and Pb) on ATP content in plant leaves grown with Hoagland solution under green house condition. The two plants, kidneybean(Phaseolus vulgaris L.) and buckwheat(Fagopyrum esculentum M nch), showed similar inhibitory effect of heavy metals on ATP content in order of Hg, Cd, Pb, and Al. But the overall inhibitory effect was greater in kidneybean than in buckwheat. The affinity of heavy metals, in vitro, toward the enzyme (luciferin-luciferase) is in order of Hg, Al, Cd, and Pb, similar to that toward ATP. The results showed that the inhibitory effect of heavy metals on ATP hydrolysis is mainly due to the coordination of heavy metals with enzyme than ATP.

• 한국표면공학회지
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• 제22권4호
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• pp.197-206
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• 1989

The Composition and throwing power-of Pb-Sn alloy deposits are investigated in tems of the pulse parameters in pulse plating. Microhardness and intermal srress of alloy deposots are measured. The current efficiency of pulse plating is lower than that of D.C.plating while cathode overpotential and macro-throwing power noticebly increase with increasing peak current density. The Pb content of P.C. plated alloy deposits with increasing average current density, is relatively lower than of D.C. plated deposits at the same average current density. The internal stress of Pb-Sn alloy is not detected and the microhardness are 9.0kg/mm2 and 11kg/mm2 for D.C. plated P.C. plated deposits, respectively.

• 한국표면공학회지
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• 제22권4호
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• pp.168-178
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• 1989

The compositions and microstructures of Pb-Sn alloy electrodeposits were investigated in terms of the electrolysis conditions conditions by using fluoborate bath. The Pb content of alloy deposit decreased with increasing dreasing current density until the limting content was obtained. The proferred orientation of Pb-phase in the alloy changed in the sequence of (110)longrightarrow(100)longrightarrow(100)+(110)(311)longrightarrowrandom distribution of crystals with increasing cathode overpotential, while that of $\beta$-Sn phase was (110)(301)(211)n mixed texture. The smooth surface with granular crystallites was obtained below medium current desity, while the rough surface texture was formed at high current density.