• 전기학회논문지P
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• 제56권2호
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• pp.65-73
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• 2007

In this study, the pulse charger and voltage regulator are proposed that can reuse the waste lead acid battery. The first we develop the voltage regulator that can reuse the waste lead battery. And the pulse current is applied to the terminal of the waste lead acid battery. The voltage regulator is available principle of the pulse current which can reduce the sulfate to incipient material such as Pb and PbO2. Therefore the internal resistance of the lead acid battery is decreased, the performance of the lead acid battery is improved and the durability is prolonged. The second we develop the pulse charger using the voltage regulator. The pulse charger uses the switch mode of the forward convert method. The pulse charger maintain the constant voltage in state removing the lead acid battery and when it connected the pulse charger, it is converted the charge mode of the constant current immediately. It continues the rapid charge until the full state of the lead acid battery. After that the pulse charger is converted to the charge mode of constant voltage automatically, and then it continues the normal charge. The experiment results show that the effectiveness of the voltage regulator and pulse charger such as the good performance and the prolonged durability in lead acid battery of the small and large capacity.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.38-43
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• 2002

A series of tests were performed to investigate the effects of pH and contamination level on cation exchange capacity and zeta potential in kaolinite loaded with lead. Test results show that cation exchange capacity of kaolinite is found to be in the range from 4 to 20meq/100g and it increased with increasing pH up to the converged number about 20meq/100g over pH 8. And then CEC has a tendency to reduce and converge to zero with increasing the concentration of Pb in the kaolinite surface. Moreover, zeta potential of kaolinite contaminated with lead is found to be in the range from -10 to 5mV, and zero point of charge is measured at about pH 3.5. Zeta potential of kaolinite contaminated with lead decreases with increasing pH values and decreasing Pb concentration of kaolinite.

• 대한화학회지
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• 제7권2호
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• pp.186-188
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• 1963

An attempt to improve the method of volumetric determination of tungsten developed by Luke has been made successfully. Using amalgam coated lead instead of pure metallic lead in the reduction procedure. W(VI)-W(III) reduction has been found to be quantitative in rather concentrated hydrochloric acid. Since there was no excessive dissolution of lead via reduction of hydrogen ion, lead surface was totally accessible for the reduction of tungsten and no trouble was caused by dereposition of $PbCl_2$ crystals at the nozzle of Jones reductor. Furthermore, it has been confirmed that almost 100 mg. of $WO_3$ can be handled easily if the chloride concentration of the HCl is increased by adding solid $NH_4Cl$.

• Journal of Welding and Joining
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• 제24권6호
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• pp.21-27
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• 2006

This study was focused on the evaluation of the thermo-mechanical board-level reliability of Pb-bearing and Pb-free surface mount assemblies. The composition of Pb-bearing solder was a typical Sn-37Pb and that of Pb-free solder used in this study was a representative Sn-3.0Ag-0.5Cu in mass %. Thermal shock test was chosen for the reliability evaluation of the solder joints. Typical $Cu_6Sn_5$ intermetallic compound (IMC) layer was formed between both solders and Cu lead frame at the as-reflowed state, while a layer of $Cu_3Sn$ was additionally formed between the $Cu_6Sn_5$ and Cu lead frame during the thermal shock testing. Thickness of the IMC layers increased with increasing thermal shock cycles, and this is very similar result with that of isothermal aging study of solder joints. Shear test of the multi layer ceramic capacitor(MLCC) joints was also performed to investigate the degradation of mechanical bonding strength of solder joints during the thermal shock testing. Failure mode of the joints after shear testing revealed that the degradation was mainly due to the excessive growth of the IMC layers during the thermal shock testing.

• 대한환경공학회지
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• 제27권11호
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• pp.1238-1243
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• 2005

본 연구에서는 해안가에서 자생하는 두 종의 해조류(Laminaria japonica와 Kjellmaniella crassifolia)를 생체흡착제로 사용하여 용액중의 중금속(납) 제거 실험을 통해 생체흡착제의 납의 흡착속도와 흡착평형 특성을 연구하였다. 두 종의 해조류을 사용한 납의 생체흡착은 흡착초기 2시간 이내에 평형에 도달하였다. 흡착속도는 유사 2차 흡착속도식에 의해 거의 정확한 모사가 가능하였으며, 여기에서 산출된 속도상수, $k_{2,ad.}$는 각각 $0.883{\times}10^{-3}$와 $0.628{\times}10^{-3}\;g/mg/min$이었다. 흡착평형은 Langmuir, Redlich-Peterson 및 Koble-Corrigan (Langmuir-Freundlich) 모델식에 의해 잘 모사되었다. 또한, L. japonica와 K. crassifolia의 4가지 중금속에 대한 선택성은 Pb>Cd>Cr>Cu와 Pb>Cu>Cd>Cr순으로 나타났다. 본 실험에 사용된 L. japonica는 pH의 증가에 따라 납의 흡착량도 증가되었다.

• 한국산업보건학회지
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• 제30권2호
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• pp.163-173
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• 2020

Objectives: The study was evaluated exposure variation and daily absorption level of cadmium, lead concentration of ambient air of monthly data from 1999 to 2017 for main exposure factor in outdoor workers. Methods: Based on the monthly data from 'The annual report of air quality in Korea from 1999 to 2018' in 'Air Korea' website in the Korean Ministry of Environment. The monthly data of PM_2.5, PM₁₀, cadmium, lead concentration of ambient air were recalculated to average, minimum, and maximum. And these data were combined to Asian-dust exposure data from 'The annual report of Asian-dust·smog in 2017' of National Institute of Meteorological Sciences in Korea. Results: Geometric mean(minimum-maximum) concentration in ambient air of monthly data were 0.0017 (ND-0.2015) mg/㎥ in cadmium and 0.0467(ND-0.8554) mg/㎥ in Pb from 1999 to 2017. Both of Cd and Pb concentration in ambient air showed the highest concentration in January and the lowest in August among annual variation from 1999 to 2017. PM₁₀ and PM_2.5 level showed the highest in March(PM₁₀) and February (PM_2.5) the lowest in August both of PM₁₀ and PM_2.5. Discussion: Based on exposure data and prior reports, daily Cd absorption was estimated to 0.013(ND-1.511) mg/day from respiration and 1.89 mg/day from daily food(25.2 mg/day of daily Cd intake). In case of Pb, daily absorption was estimated to 0.350(ND-6.416) mg/day from respiration and 1.38-1.71 mg/day from daily food intake. Conclusion: Cd and Pb with Asian-dust have high influential factor to increase the Cd and Pb exposure at Winter and Spring season in outdoor workers.

• 대한금속재료학회지
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• 제50권11호
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• pp.829-838
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• 2012

The microstructure, chemical composition, and lead isotope ratio of the Buddhist bell of Yongmoon Mountain Sangwonsa temple, which was selected as one of the three great bells of Korea by Japanese historians, were analyzed in order to estimate the origin of the material and the time of casting. The microstructure of the temple bell was composed of a copper matrix phase with ${\alpha}$, a face centered cubit lattice structure, a ${\delta}$ phase with $Cu_{41}$ $(Sn,Ag,Sb)_{11}$ as the chemical structural formula, dispersed lead and $Cu_2S$ particles, and locally agglomerated fine particles. Through analysis of the chemical composition of the bell, a criterion (Pb: 0-3.0 wt%, Sn: 10-15 wt%) for distinguishing the bells of the Shilla dynasty from the bells of the Koryo Chosun dynasty is proposed. Examining the lead isotope ratio of $^{207}Pb/^{206}Pb$ and $^{208}Pb/^{206}Pb$ of the Buddhist bell of Sangwonsa temple proved that the bell was fabricated using raw materials in South Korea, which led to the conclusion that the bell was cast in Korea and the top board of the bell has been damaged by an unknown individual. The criteria of distinguishing the bells from the Shilla dynasty from the bells of the Koryo Chosun dynasty presented for the first time in this research is expected to aid in identifying and estimating the previously unclear production years of other bells.

• 환경생물
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• 제30권2호
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• pp.128-135
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• 2012

본 연구는 말똥성게(Hemicentrotus pulcherrimus)의 생식세포 및 pluteus 유생을 이용하여 중금속인 납(lead, Pb)과 아연(zinc, Zn)의 독성을 조사였다. H. pulcherrimus 배우자 및 배아에 미치는 Pb과 Zn의 독성은 각각 31, 63, 125, 250, 500 ppb 및 16, 31, 63, 125, 250 ppb의 농도에서 조사하였다. 0.5 M KCl 용액을 이용하여 방란 및 방정을 유도하였고, 수정률 및 정상 배아발생률의 조사는 수정 후 각각 10분 및 64시간째 관찰하여 시행하였다. Pb 노출 시 수정률은 대조군과 비교하여 유의적인 변화가 없었다. 그러나 정상 배아발생률은 농도가 높을수록 농도의존적으로 유의적인 감소를 보였다. Zn을 노출시켰을 경우 수정률과 정상 배아발생률은 농도가 높을수록 농도의존적인 유의적 감소를 나타냈다. H. pulcherrimus의 정상 배아 발생에 대한 독성치는 각각 Pb (반수 영향농도 ($EC_{50}$) 45.13 ppb, 95% Cl 40.12~50.05 ppb), Zn (반수영향농도 ($EC_{50}$) 19.82 ppb, 95% Cl 18.26~21.31 ppb)로 나타났다. 또한 Pb과 Zn의 무영향농도(NOEC)는 각각 <31.25 ppb 및 <15.63 ppb로 나타났고, 최소영향농도(LOEC)는 31.25 및 15.63 ppb로 나타났다. 본 연구 결과, H. pulcherrimus의 초기 배아발생 과정은 Pb과 Zn 등의 중금속에 높은 민감성을 보인다. 따라서 H. pulcherrimus는 해양생태계 위해 평가를 위한 시험생물로서 사용이 가능하다고 사료된다.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 3rd Korea-Japan Advanced Semiconductor Packaging Technology Seminar
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• pp.21-50
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• 2001

EC's/Japanese environmental regulation drive the Pb-free/Halogen-free application. Most Japanese electronics companies are preparing the green products. All items concerning to Pb-free/Halogen-ree technology should be coparallely designed and developed. More works need to clear the unknowns on Pb-free materials. Need of consensus on materials and standards. EBM (Environmental Benign Manufacturing)

• 헤리티지:역사와 과학
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• 제36권
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• pp.241-266
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• 2003

Glass pieces excavated from Mireuksa Temple dated $7^{th}$ century A.D. were characterized by chemical composition, specific gravity and melting point. Lead isotope ratios of lead glasses were also compared with those of lead ore to attribute which lead ore was delivered for making lead glass. It was known that some lead glasses found in Japan were similar with those of Mireuksa Temple as comparing the data of chemical composition and lead isotope ratios. Characteristics of lead glass from Mireuksa Temple Thirty five glass pieces of Mireuksa Temple were analyzed for five oxides and found that all was lead glass system(PbO-$SiO_2$) with the range of 70~79% for PbO and 20~28% for $SiO_2$. The concentrations of oxides such as $Al_2O_3$, $Fe_2O_3$ and CuO were below 0.4%, 0.3% and 0.9%, respectively. Principal component analysis(PCA) as a statistical method was carried out to classify glasses with the similarities of chemical concentrations. The result of PCA has shown that three groups of glasses were created according to the excavation positions and two major oxides(PbO and $SiO_2$) greatly contributed to the dispersion of glasses on principal component 1(PC1) axis and trace element oxides($Al_2O_3$ and $Fe_2O_3$) for PC2 axis. Most of lead glasses were greenish by the efficacy of iron and copper oxides and some showed yellowish-green. The gravity of lead glasses was about 4.4~5.4 and estimated melting point was near $670^{\circ}C$. Lead isotope ratios of glasses were analyzed and found quite close to a lead ore from the Bupyeong mine in Gyeonggi-do. Comparison with lead glasses found in Japan Lead glasses of Mireuksa Temple were compared with those of Japan on the basis of chemical and physical data. Chemical compositions of Japanese lead glasses dated $7^{th}{\sim}8^{th}$ century A.D. were nearly similar with those of Mireuksa Temple but lead isotope ratios of those were separated into two groups. Three distribution maps of lead ores of Korea, Japan and China with lead isotope ratios were applied for lead glasses found in Japan. The result have shown that the locations of lead glasses from Fukuoka Prefecture coincided with the region of northen part of Korea and similar with those of Mireuksa Temple and lead glasses from Nara Prefecture dated $8^{th}$ century A.D. were located in the region of Japanese lead ore. This research has demonstrated that lead glasses of Mireuksa Temple conveyed to Miyajidake site, Fukuoka Prefecture around $7^{th}$ century A.D. and glass melting pots and glass beads excavated from Nara Prefecture confirmed the first use of Japanese lead ore for production of lead glasses from the end of $7^{th}$ century A.D.