• Journal of the Korean Wood Science and Technology
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• v.46 no.5
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• pp.541-552
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• 2018

As the use of wood pellets increases, there is an increasing interest in the safety of the wood pellets themselves to avoid physical and chemical damage to people and the environment. This study investigated the contents of nitrogen, sulfur, chlorine, arsenic, cadmium, chromium, copper, lead, mercury, nickel, zinc, and cesium in wood pellets distributed in Korea as a preliminary survey for establishing safety evaluation standards for wood pellets. Nitrogen, sulfur, chlorine, and heavy metal contents of wood pellets produced in Korea met the specification for the 1st grade of wood pellets determined by the National Institute of Forest Science and the specification for the commercial and residential wood pellets of A1 grade determined by the ISO and the evaluation standards for wood pellet safety determined by the Korean Forest Service. However, among imported wood pellets, some wood pellets contained nitrogen, sulfur, chlorine, and heavy metal exceeding the safety evaluation standards. Cesium radioactivity was not detected in domestic wood pellets. Cesium radioactivity was detected from wood pellets imported from Japan, but it was below the limits specified in the wood pellet safety evaluation standards. In conclusion, by establishing safety standards for wood pellets, we believe that safe wood pellets will be used.

• Journal of Oral Medicine and Pain
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• v.42 no.4
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• pp.102-108
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• 2017

Purpose: Many metal ions released from dental casting alloys have been reported to influence the intraoral symptoms of oral lichen planus (OLP) and burning mouth syndrome (BMS). The aim of this study was to investigate the relationship between salivary metal ion levels and the prosthetic duration as well as to evaluate the time-dependent morbid effects of metal ions in OLP and BMS patients. Methods: Three study groups consist of the following subjects respectively: 17 OLP patients, 12 BMS patients, and 12 patients without oral symptoms. The salivary concentrations of 13 metal ions (copper, cobalt, zinc, chromium, nickel, aluminum, silver, iron, titanium [Ti], platinum, tin, palladium, and gold) were measured by Laser Ablation Microprobe Inductively coupled Plasma Mass Spectrometry. Results: The Ti ions had statistically significant differences among the groups with a prosthetic duration of less than 5 years. There were no significant differences between all ion levels among the groups wearing dental cast alloys for over 5 years. In the BMS group, the level of Ti ions in patients with prosthetic restorations less than 5 years old were significantly high (p<0.05). Conclusions: In the BMS group, 3-60 months during which salivary Ti levels were higher were matched with the duration of burning symptoms ($15.6{\pm}17.1months$). Furthermore, Ti ions were statistically high in the oral cavity of BMS patients fitted with dental casting alloys for 5 years. These results suggest that Ti ions released from dental implants and oral prostheses could attribute to burning sensation of BMS.

• Journal of Nutrition and Health
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• v.12 no.3
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• pp.25-32
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• 1979

In order to investigate harmful trace elements in ford additives used in food processing the contents of Copper, Lead, Cadmium, Chromium, Manganese, Nickel and Iron are determined by Atomic Absorption Spectrophotometer. These Elements are Extracted with APDC-MIBK extract method. Samples are collected from the food Industrial companies in Korea. Samples studied as shown in Table 1 are food colors(3-samples, Flavoring Agents(7-samples), Acidifiers(4-samples) Baking Powders(4-samples), Emulsifiers(2-samples), Thickeners(2-samples), Antioxidants(2-samples), Intensifiers(2-samples), Seasonings(3-samples), modifiers (10-samples) Most of the food additives contained comparatively a little small amount of harmful trace elements. However, the contents of harmful trace elements of Sodium Carbonate, Food Yellow No.5, Food Blue No.1, Food Red No.2 and Alkalies added in noodles are significantly higher than the other food additives. The obtained results are as follows ; 1) Sodium Carbonate contained Cadmium; 16.73 ug/g and Lead ; 61.55 ug/g. 2) Food Yellow No. 5 contained Cadmium: 1.67ug/g and Lead; 23.46 ug/g. 3) Food Blue No. 1 contained Cadmium; 1. 16 ug/g and Lead; 23.46 ug/g. 4) Food Red Ho. 1 contained Cadmium; 1.91 ug/g and Lead 23.08 ug./g. 5) Alkalies added in noodles contained Cadmium; 6. 11 ug/g and Lead; 53.85 ug/g.

• Fisheries and Aquatic Sciences
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• v.17 no.3
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• pp.313-318
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• 2014

From 2008 to 2013, the mussel Mytilus galloprovincialis were collected from a major area of mussel production (Changseon area), which is a designated shellfish-cultivating area for export, located on the southern coast of Korea. The samples were analyzed for mercury (Hg) using a direct Hg analyzer and for other metals, such as cadmium (Cd), lead (Pb), arsenic (As), chromium, copper, nickel, and zinc, using inductively coupled plasma mass spectrometry. The concentrations and bioaccumulation of the heavy metals were determined, and a potential risk assessment was conducted to evaluate their hazards towards human consumption. The concentration and bioaccumulation ratio of Cd were the highest of the three hazardous metals (Cd, Pb, and Hg). The concentrations of hazardous metals in all samples were within the limits set by Korea and other countries. The estimated dietary intake (EDI) was compared to the provisional tolerable daily intake (PTDI) adopted by the Joint FAO/WHO Expert Committee on Food Additives and the U.S. Environmental Protection Agency. The EDIs of all heavy metals tested for mussel samples ranged from 0.01 to 4.99% of the PTDI; the highest value was measured for As. The hazard index (HI) can be used to assess the risk of heavy metal consumption associated with contaminated food. The HI for all samples was far less than 1.0, which indicates that the mussels produced in the Changseon area do not represent an appreciable hazard to humans and are fit for consumption.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.1
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• pp.41-48
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• 2010

Uranium deposits from an electrorefining process contain about 30% salt. In order to recover pure uranium and transform it into an ingot, the salts have to be removed from the uranium deposits. Major process variables for the salt distillation process of the uranium deposits are hold temperature and vacuum pressure. Effects of the variables on the salt removal efficiency were studied in the previous study[1]. By applying the Hertz-Langmuir relation to the salt evaporation of the uranium deposits, the evaporation coefficients were obtained at the various conditions. The operational conditions for achieving above 99% salt removal were deduced. The salt distilled uranium deposits tend to form the eutectic melt with iron, nickel, chromium for structural material of salt evaporator. In this study, we investigated the hold temperature limitation in order to prevent the formation of the eutetic melt between urnaium and other metals. The reactions between the uranium metal and stainless steel were tested at various conditions. And for enhancing the evaporation rate of the salt and the efficient recovery of the distilled salt, the thermal analysis of the salt distiller was conducted by using commercial CFX software. From the thermal analysis, the effect of Ar gas flow on the evaporation of the salt was studied.

• Journal of Technologic Dentistry
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• v.33 no.1
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• pp.37-45
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• 2011

Purpose: Heat pressed ceramics, used for all ceramic restorations, have the additional advantage of being technically less change through using of the lost-wax technique. Conceptually, combining the ceramic with the clinically proven reinforcing ability of a metal framework would be advantageous; however, cause of mismatching of fusion between ceramics and metal frameworks which from differences of casting temperature and coefficient of thermal expansion, pressed ceramics could not be used with a metal framework. The purpose of this study was to compare shear bond strength of press-to metal ceramic to porcelain fused non precious metal and feldspatic porcelain fused non precious metal. Methods: The 30 metal specimens were casted in a porcelain fused non precious metal nickel-chromium alloy. They were divided into 3 groups by surface treatment and applied ceramic: $125{\mu}m$ aluminium oxide sandblasting and veneered feldspatic porcelain (group FP), $125{\mu}m$ aluminium oxide sandblasting and had press-to-metal ceramic applied (group PC), porcelain bonder (gold bonder) fused on surface of metal specimens and had press-to-metal ceramic applied (group PCG). In each group 10 metal specimens were used. The press-to-metal ceramic applied 20 specimens had ash-free wax pattern applied, the metal-wax complexes invested, and were pressed with heat press ceramic. All specimens were subjected to shear bond strength test at a crosshead speed of 1.0 mm/min. Results: The results of measured in Mean SD and data were analyzed by one-way AVOVA (p= .05) and Tukey HSD test (p= .05).: group FP $16.090{\pm}1.841$ MPa, group PC $12.620{\pm}1.8256$ MPa, group PCG $10.920{\pm}0.9283$, significant differences between all groups (p < .05). Significant differences were found in each between group FP and group PC, group FP and group PCG (p < .05). Conclusion: The shear bond strength of press-to-metal ceramic to porcelain fused non precious metal was described higher in unused gold bonder group than used gold bonder groups.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.3
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• pp.193-202
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• 2013

The concentrations of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), zinc (Zn), nickel (Ni), and arsenic (As) in sand samples collected from selected children's playground and their correlation with environmental parameters, such as concentration of particulate matter in the atmosphere ($PM_{10}$), apartment age (> 5 years), clay and organic matter contents in sand samples, were analyzed. The average heavy metal concentration in samples was 0.040 mg $kg^{-1}$ for Cd, 0.200 mg $kg^{-1}$ for Cr, 1.75 mg $kg^{-1}$ for Cu, 15.1 mg $kg^{-1}$ for Ni, 3.42 mg $kg^{-1}$ for Pb, 66.7 mg $kg^{-1}$ for Zn and 0.750 mg $kg^{-1}$ for As, all of which were below the environmental regulatory level established by Korea Ministry of Environment. However, in the consideration of direct and oral exposure by children to playground sand, the risk of the concentration range in the samples might be greatly enhanced. Heavy metal concentration in samples collected from high $PM_{10}$ (> $70{\mu}gm^{-3}$) area was slightly greater than in samples from low $PM_{10}$ (< $70{\mu}gm^{-3}$), indicating the contribution of particulate matter in air phase to heavy metal concentration in playground sand samples. The concentrations of both Cd and Pb were the highest in apartments older than 21 years (0.050 mg $kg^{-1}$ and 5.28 mg $kg^{-1}$ for Cd and Pb respectively) and showed positive correlation with apartment age (p<0.01 and p<0.001 for Cd and Pb, respectively). Clay content in playground sands ranged 3.8~11.2% and was positively correlated with heavy metal concentration. Organic matter content was negligible (mostly < 0.1%) and showed poor correlation with heavy metal concentration. In conclusion, concentration of heavy metals in playground sand was found to be predominantly influenced by the apartment age and clay content in sand samples and supplemented by dust deposition of particulate matter ($PM_{10}$) from atmosphere.

• Safety and Health at Work
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• v.1 no.2
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• pp.134-139
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• 2010

Objectives: The lung cancer mortality in Korea has increased remarkably during the last 20 years, and has been the first leading cause of cancer-related deaths since 2000. The aim of the current study was to examine the time trends of occupational lung cancer and carcinogens exposure during the period 2006-2009 in South Korea, by assessing the proportion of occupational burden. Methods: We defined occupational lung cancer for surveillance, and developed a reporting protocol and reporting website for the surveillance of occupational lung cancer. The study patients were chosen from 9 participating university hospitals in the following 7 areas: Seoul, Incheon, Wonju, Daejeon, Daegu, Busan, and Gwangju. Results: The combined proportion of definite and probable occupational lung cancer among all lung cancers investigated in this study was 10.0%, 8.6%, 10.7%, and 15.8% in the years 2006 to 2009, respectively, with an average of 11.7% over the four-year study period. The main carcinogens were asbestos, crystalline silica, radon, polyaromatic hydrocarbons (PAHs), diesel exhaust particles, chromium, and nickel. Conclusion: We estimated that about 11.7% of the incident lung cancer was preventable. This reveals the potential to considerably reduce lung cancer by intervention in occupational fields.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.3
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• pp.69-75
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• 2016

This study investigated the effect of heat treatment conditions not only on the Cr surface crack propagation behaviors but also on the Ni/Cr interfacial reaction characteristics in electroless Ni/electroplated Cr double coating layers on Cu substrate. Clear band layer of Ni-Cr solid solutions were developed at Ni/Cr interface after heat treatment at $750^{\circ}C$ for 6 h. Channeling cracks formed in Cr layer after 1 step heat treatment, that is, heat treatment after Ni/Cr plating, while little channeling cracks formed after 2 step heat treatment, that is, same heat treatments after Ni and Cr plating, respectively, due to residual stress relaxation due to crystallization of Ni layer before Cr plating.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.4
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• pp.302-324
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• 2022

Objectives: The objective of this study is to investigate exposure to occupational carcinogens in the nationwide electronics industries and to establish a strategy for control of occupational carcinogens in South Korea. Methods: We evaluated occupational carcinogens as defined by International Agency for Research on Cancer (IARC) using a nationwide work environment measurement database on the electronics industry in South Korea measured between 2013 and 2017 in accordance with the Occupational Safety and Health Act. Results: The number of occupational carcinogens found in the electronics industry in South Korea were: 20 for IARC Group 1, 14 for Group 2A, and 30 for Group 2B. The occupational carcinogens (Group 1) most frequently exposed were strong-inorganic-acid mists containing sulfuric acid (sulfuric acid), welding fumes, mineral oils (untreated or mildly treated), nickel compounds, silica dust, crystalline substances in the form of quartz or cristobalite, formaldehyde, arsenic and inorganic arsenic compounds, chromium (VI) compounds, trichloroethylene, cadmium and cadmium compounds, vinyl chloride, ethylene oxide, wood dust, beryllium and beryllium compounds, 1,3 butadiene, benzene, and others. Among them, the carcinogens (Group 1) exceeding the acceptable standard were trichloroethylene, formaldehyde, and ethylene oxide. The working environment measurement system as regulated by Occupational Safety and Health Act is not properly assessed and managed for occupational carcinogens in South Korea. A component analysis for all materials used should be set up to practically reduce occupational carcinogens. A ban on the use of occupational carcinogens and the development of alternative materials are needed. The occupational carcinogens below the acceptable standards should be carefully examined and a new standard for exposure needs to be established. Conclusions: The Occupational Safety and Health Act should be improved to identify and monitor occupational carcinogens at work sites. A strategy for occupational safety and health systems should be provided to give direction to workers' needs and right to know.