• Resources Recycling
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• v.22 no.5
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• pp.50-55
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• 2013

The recovery of copper from spent photovoltaic ribbon was conducted using thermal treatment method at the range of temperature of $300^{\circ}C$ to $600^{\circ}C$ under inert atmosphere. The coating layer consisted of lead of 68.99 wt.% and tin of 31.21 wt.% was melted down at elevated temperatures and was collected on the bottom of crucible. The chemical composition of copper ribbon after thermal treatment was analyzed by ICP-MS (Inductively coupled plasma mass spectrometry) and the purity of copper was found to be obtained up to about 96 wt.% regardless of temperatures. The cross-sectional area of the specimen was also examined by SEM (scanning electron microscopy) and EDX (energy dispersive X-ray microscopy).

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.11a
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• pp.1-2
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• 2000

In chip plating, several parameters must be taken into consideration. Current density, solution concentration, pH, solution temperature, components volume, chip and media ratio, barrel geometrical shape were most likely found to have an effect to the process yields. The 3 types of barrels utilized in chip plating industry are the onventional rotating barrel, vibrational barrel(vibarrel), and the centrifugal type. Conventional rotating barrel is a close type and is commonly used. The components inside the barrel are circulated by the barrel's rotation at a horizontal axis. Process yield has known to have higher thickness deviation. The vibrational barrel is an open type which offers a wide exposure to electrolyte resulting to a stable thickness deviation. It rotates in a vertical axis coupled with multi-vibration action to facilitate mixed up and easy transportation of components. The centrifugal barrel has its plated work centrifugally compacted against the cathode ring for superior electrical contact with simultaneous rotary motion. This experiment has determined the effect of barrel vibration intensity to the plating thickness distribution. The procedures carried out in the experiment involved the overall plating process., cleaning, rinse, Nickel plating, Tin-Lead plating. Plating time was adjusted to meet the required specification. All other parameters were maintained constant. Two trials were performed to confirm the consistency of the result. The thickness data of the experiment conducted showed thatbthe average mean value obtained from higher vibrational intensity is nearer to the standard mean. The distribution curve shown has a narrower specification limits and it has a reduced variation around the target value. Generally, intensity control in vi-barrel facilitates mixed up and easy transportation of components. However, it is desirable to maintain an optimum vibration intensity to prevent solution intrusion into the chips' internal electrode. A cathodic reaction can occur in the interface of the external and internal electrode. 2H20 + e $\rightarrow$M/TEX> 20H + H2.. Hydrogen can penetrate into the body and create pressure which can cause cracks. At high intensity, the chip's motion becomes stronger, its contact between each other is delayed and so plating action is being controlled. However, the strong impact created by its collision can damage the external electrode's structure there by resulting to bad plating condition.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.05a
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• pp.23-27
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• 2005

Electrogenerated chlorine leaching of used printed circuit board was Investigated in hydrochloric acid solution. The used printed circuit board contained about 45% of metal component, in which copper was about 84%. The leaching rate was greatly effected by current density and agitation. Utilization of electrogenerated chlorine was enhanced by increasing agitation and lowering current density. Leaching of copper was suppressed, while the minor metal elements, such as aluminum, lead, and tin, dominated the leaching at the initial stage.

• Resources Recycling
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• v.28 no.3
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• pp.68-76
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• 2019

It is very necessary for the metal recycling industries and the researchers to understand the current status of demand and supply of non-ferrous metals and their scraps. Domestic demand and supply of non-ferrous metals and their scraps have been surveyed and reported on the journal of the Korean Institute of Resources Recycling since ten years before. However, it was confined to six major non-ferrous metals such as copper, aluminum, zinc, lead, nickel and magnesium because there are so many kind of non-ferrous metals. In this article also, demand and supply of these non-ferrous metals in addition tin during recent five years (2014 ~ 2018) in Korean markets were reviewed, and their recycling ratio of scraps were briefly estimated. The statistical data were mainly cited from the data issued by Korea Customs Service (KCS) and Korea Non-Ferrous Metal Association, and some fragmental published review articles from magazines and other technical reports.

• Journal of architectural history
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• v.31 no.4
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• pp.7-16
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• 2022

Since the beginning of the second Sino-Japanese war in 1937, the entire Korean Peninsula has entered a full-fledged wartime system. Japan enacted laws that strongly regulate the distribution of various resources for war, and the same was implemented in Joseon. In particular, as iron, copper, lead, tin, and aluminum were mobilized as raw materials for military supplies such as weapons, private distribution decreased significantly, which had a great impact on the construction industry. As the use of metal such as steel as building materials requires permission from the provincial governor, it has become difficult to supply and demand except for some military facilities. In addition, the Japanese Ministry of Commerce and Industry encouraged research and development and manufacturing to promote the so-called "substitute goods industry" to make up for the shortage of supplies. Products with improved performance through chemical treatment by injecting only a small amount of the same raw material than before or using alternative raw materials have been developed. It was intended to overcome the limitations of lack of raw materials through the chemical industry. In terms of building materials, various substitutes were produced due to the incorporation of petrochemicals and the use of synthetic resins. This trend continued even after the end of the war and served as one of the backgrounds for R&D and production of new materials without returning to the "substitute goods."

• Journal of Life Science
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• v.26 no.5
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• pp.503-508
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• 2016

Biosensors have been used as first-step monitoring tools to detect on-site samples in a simple and cost-effective manner. Numerous recombinant microbial biosensors have been exploited for monitoring on-site toxic chemicals and biological signals. Herein, a recombinant microbial biosensor was constructed for monitoring cadmium. The cadmium responding cadC regulatory gene and it’s promoter from Staphylococcus aureus was amplified through PCR, fused with the lacZ gene, and transformed into Escherichia coli BL21 (DE3) cells. In the presence of cadmium, the biosensor cells express β-galactosidase showing red color development with chlorophenol red β-galactopyranoside (CPRG) as the enzymatic substrate. The biosensor cells showed the best β-galactosidase activity after 3 hr induction with cadmium at pH 5 and a detection range from 0.01 μM to 10 mM cadmium with a linearity from 0.01 to 0.1 μM cadmium (y = 0.98 x + 0.142, R² = 0.98). Among the heavy metals, cadmium and lead showed good responses, tin and cobalt showed medium responses, and mercury and copper showed no responses. The biosensor cells showed good responses to several waste waters similar to buffer solution, all spiked with cadmium. The biosensor described herein could be applied for on-site cadmium monitoring in a simple and cost-effective manner without sample pretreatments.

• Journal of Conservation Science
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• v.36 no.3
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• pp.178-186
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• 2020

Verdigris is a traditional artificial pigment reported on old research papers and according to the methods mentioned in the literature, it is manufactured by the corrosion of copper or copper alloys using vinegar and by further scraping the generated rust. Since the Three Kingdoms Period, various household products with copper alloys, such as bronze and brass, have been used, and pigment analysis of these cultural heritage items has revealed the presence of tin, zinc, lead, and copper in green pigments. Based on these data, five types of verdigris were prepared from copper and copper alloys, and analyzed. the analysis results revealed a bluish green pigmentation, and the chromaticity, particle shape, and oil absorption quantity of each verdigris differed based on the type of copper alloy used in its preparation. The main components of verdigris are Cu, Sn, Zn and Pb, and their proportions depended on the type of copper alloy used during manufacturing. However, the main constituent mineral of the pigments is the same as 'hoganite[Cu(CH₃COO)₂·H₂O]', regardless of the copper alloy used. The result of accelerated weathering test for stability evaluation revealed that verdigris was discolored rapidly, thereby indicating that its stability was low, in particular, the pigments comprising lead presented relatively lower stability.

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.748-752
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• 1995

Canned and bottled orange juices currently sold in Korean market were stored for 24 weeks at 20, 30, 40 and $50^{\circ}C$ and analyzed after opening at 4 week intervals. Activation energy, $Q_{10}$ values and shelf-life at respective temperatures were calculated from the data on various quality indexes. Proposed indexes were lead, tin, iron and vitamin C contents in canned juices and vitamin C content and browning index in bottled juices and $Q_{10}$ values for these parameters were in the range of $1.3{\sim}2.0$. Shelf-life calculated for canned juices at 10, 20 and $30^{\circ}C$ were 10, 6 and 3 months and that in bottled juices, 24, 12 and 6 months, respectively. When the distribution temperature of juices in Korea is assumed to be $15^{\circ}C$ average, the optimum shelf-life was estimated to be 8 months in canned juices and 18 months in bottled juices. In order to ascertain the safety of canned orange juices, efforts are needed to re-examine the recommended distribution period, legal limit for lead and improvement of container materials.

• Journal of the Korean Solar Energy Society
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• v.34 no.1
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• pp.98-104
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• 2014

Photovoltaic (PV) cell is considered as one of the finest ways to utilize the solar power. A study of improving solar cell's efficiency is important because the lifetime of solar cell is determined by photovoltaic module technology. Therefore, oxidation (and/or corrosion) of solder materials will be one of the primary yield and long-term reliability risk factor. Recently, the development of lead-free solder alloy has been done actively about lead-free solder alloys of the thermodynamic and mechanical properties. However, the oxidation behavior have rarely been investigated In this study, the oxidations of 60 wt% Sn-40 wt% Pb, 62 wt% Sn-36 wt% Pb -2 wt% Ag, 50wt% Sn-48 wt% Bi-2 wt% Ag alloys for the interconnect ribbon after exposure in atmosphere at $100^{\circ}C$ for several times were investigated. The wettability of 62 wt% Sn-36 wt% Pb-2 wt% Ag and 50 wt% Sn-48 wt% Bi-2 wt% Ag solders was also studied to compare with that of 60 wt% Sn-40 wt% Pb alloy. The results howed that the zero cross time and the wetting time of 50 wt% Sn-48 wt% Bi-2 wt% Ag solder were better than other two samples. The surface of tested samples was analyzed by XPS. The XPS result showed that in all samples, SnO grew first and then the mixture of SnO and $SnO_2$ was detected. $SnO_2$ grew predominantly for the long time aging. Moreover XPS depth profile analysis has found surface enrichment of tin oxide.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.561-567
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• 2003

This study was conducted to estimate the heavy metal contents in various foods (n=696). The contents of lead (Pb), cadmium (Cd) and tin (Sn) were determined using and ICP (inductively coupled plasma spectrometer). The content of mercury (Hg) was determined using a mercury analyzer. The values of heavy metals in canned foods were as follows [minimum-maximum (mean), mg/kg]; Pb 0.001${\sim}$0.36 (0.10), Cd 0.001${\sim}$0.10 (0.04), Sn 0.01${\sim}$24.75 (2.60). The mean values of Pb and Cd in animal foods were 0.40 mg/kg and 0.03 mg/kg. Also, the mean values of heavy metals in vegetables and potatoes were 0.03 mg/kg for Pb, 0.02 mg/kg for Cd, 0.001 mg/kg for Hg, respectively. The mean values of Hg in fishes and canned fishes were 0.08 mg/kg and 0.04 mg/kg. Our results showed that heavy metal contents in various foods available on markets were similar to those reported in other countries.