• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.395-400
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• 2002

Epoxy coating and sealing used in nuclear plants for the protection of radiation degrades with aging and hazardous atmosphere. In order to evaluate the degradation of the epoxy, dependence of the acoustic impedance on the change of mechanical properties has been used. Unlike metals, the surface of the epoxy coating on a concrete liner is so wavy that the acoustic impedance is difficult to measure by using the reflectivity of the ultrasound on the interface surface because of the irregular reflection and propagation from the epoxy surface. SA(simulated annealing) algorithm is applied to calculate the acoustic impedance using a reflection wave from the rough epoxy surface. The surface waviness and acoustic impedance are taken into account and determined by SA method to evaluate the state of degradation quantitatively.

• Journal of Environmental Science International
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• v.2 no.1
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• pp.9.2-19
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• 1993

A laboratory study was conducted to investigate the immobilization of the laboratory waste sludge, mainly from chemical oxygen demand (COD) waste, using cementitious binders. The binders were: Ordinary Portland Cement (OPC), and lime-Rice Husk Ash (RHA) cement. The economic evaluation was done for three different kinds of cementitious binders, namely, OPC, Portaind Rice Husk Ash Cement (PRHAC) which contained rice husk ash U percent by dry weight, and lime-RHA cement. The result showed that lime-RHA cement was the cheapest. The applicability of Freundlich's desorption isotherm was studied to assess the teachability of sludges. The teachability of cement mortars was found to follow the desorption isotherms. Therefore, it was concluded that based on this test, the leachate concentrations of the solidified heavy metals could be predicted, approximately by the Freundlich's isotherm desorption modeling.

• Analytical Science and Technology
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• v.22 no.6
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• pp.504-513
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• 2009

In this study, the safety of commercial herbal medicines was evaluated by determining concentration of hazardous heavy metals. 3,152 samples (244 types) purchased by individual packing unit from market in Seoul, were analyzed using ICP-MS and mercury analyzer. As a result, the content (mg $kg^{-1}$) of Pb was higher in the above-ground part (0.92) than underground part (0.43). But in case of As and Cd contents, there is slightly higher in the underground-parts (0.26, 0.13) than the above-ground parts (0.18, 0.08). There were many herbal medicines exceeding regulatory limits of Cd comparing with other metals. The levels of Hg seemed to be different between above-ground part(0.009) and underground part (0.008) but there was no sample exceeding tolerance limits. In the comparison of imported samples with domestic herbal medicines, it was shown that Pb, As, and Hg were measured highly in the imported ones, Cd was not significantly different (t-test, p<0.05). The significant correlation was observed between Pb and As (r=0.386, p<0.01) but there was no difference in other parts. The heavy metal contamination of herbal medicines measured in total amount of respective heavy metals (mg $kg^{-1}$) was high in Flos (6.241) and Caulis (2.238), and decreased in the order of Cortex (1.634), Herba (1.154), Perithecium (0.861), Rhizoma (0.828), Radix (0.825), Fructus (0.475), and was low in Semen (0.422) (ANOVA-test, p<0.05).

• Journal of Food Hygiene and Safety
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• v.37 no.3
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• pp.166-172
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• 2022

This study evaluated the migrant and residue tests of lead (Pb), cadmium (Cd), nickel (Ni), arsenic (As), and antimony (Sb) in 70 tumbler samples. The migration levels of hazardous metals in all the samples were within the migration limits outlined in the Korean standards and specifications for utensils, containers, and packages. Moreover, in all the tumbler samples, only Ni was detected in 0.5% citric acid solution of a food stimulant. The maximum level of Ni 0.0144 mg/L was 14.4% of the migrant specification (not more than 0.1 mg/L), which was relatively safe. The 0.5% citric acid solution was eluted at 4℃, 70℃, and 100℃ for 30 min, and only Ni was detected while testing for migration levels according to the temperature variations; all temperature conditions conformed to the standards. The level of Ni migration increased significantly with increasing migration temperature. Regarding the residue level outside the paint-coated tumbler samples, the Pb level was found to range from N.D. to 20638.1323 mg/kg. The risk of Ni was further estimated to be at a safe level of 0.00 to 0.01% compared to the %TDI as a result.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.8
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• pp.992-1003
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• 2003

This study analyzes the actual state of the working uniforms worn by burning waste workers to protect their body from the hazardous environment. Directions for improvement of the clothing fabrics is also suggested. We visited and interviewed those persons who worked in the burning waste plant in Seoul and in Gyunggi Province. 245 workers were surveyed by questionnaires, and 211 workers out of 245 were statistically analyzed. Frequencies and percentages were calculated and $\chi$$^2$ test, ANOVA and Scheffe Post hoc comparison methods were utilized to test some hypothesis. The working uniforms were classified as four general types: separate type, disposable-coverall. overall, and winter clothes. At present, the working uniforms are not suitable for the conditions which they are used. There is a lack of ventilation and an inability to absorb perspiration limited elasticity, and the uniforms are prone to static shock. The degree of satisfaction varied significantly, based on the worker's educational background and main work. However, only a small percentage of workers interviewed were satisfied with the appearance and the fit of the present working uniforms. The working duration had a negative impact on the satisfaction of the worker. This results suggest that materials, colors, design and size of working clothes must be improved. The suggestions are as follows: Firstly. to use disposable non-woven fabrics finished to increase moisture regain. Secondly. to use the bad air permeability fabrics to protect the skin from absorbtion of harmful gases, flying dust, heavy metals, etc.

• Journal of Korea Soil Environment Society
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• v.5 no.1
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• pp.55-63
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• 2000

Bentonite has low hydraulic conductivity and high sorption capacity to limit hazardous heavy metals migration, and thus it has been considered as a liner material for the landfill of hazardous wastes. With a domestic bentonite sorption tests were carried out to investigate the adsorption isotherm and the effect of solution chemistry and temperature on adsorption. Freundlich isotherm was applied to fit the experimental data of lead adsorption, which fitted them well. Freundlich constants and correlation coefficient were calculated to be $K_{F}$\;=\;1.14$, n = 1.70, and $r^{2}\;=\;0.99$, respectively. The distribution coefficients($K_{d}$) for the adsorption of lead decreased with increasing initial lead concentration. The IL increased with increasing the pH of solution and sharply increased at pH > 7, which was attributed to the precipitation of lead species. The IL decreased with increasing the ion strength of solution. The $K_{d}$ gave a small increase with the concentration of ${SO_4}^{-2}$, whereas it had a nearly constant level with the concentration of ${HCO_3}^{-}$ in solution. An increase in the temperature of experimental solution increased the $K_{d}$.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.2
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• pp.183-190
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• 2007

In this study, we have investigated waste incinerators which are one of the major HAPs emission sources. In order to obtain more reliable HAPs emission data from waste incinerators, direct sampling for the possible pollutants from the stack was carried out and the analysis was performed. The purpose of study was to understand the emission status from waste incinerators and recognize the problems and finally to set up a strategy to reduce the HAPs emissions from waste incinerators. The emission concentrations of 8 species of heavy metals and 16 species of PAHs have been analyzed for the first time in Korea. Not only the emission characteristics of HAPs from waste incinerators were identified, but also the analysis of reduction efficiencies for control devices such as BF and wet scrubbing systems was carried out.

• Journal of the Korea Organic Resources Recycling Association
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• v.4 no.2
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• pp.47-53
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• 1996

This study was carried out to estimate the amount and the characteristics of sewage sludge disposed of in the Nanjido sludge landfill site. Boring test was conducted to estimated the landfill volume and to get sludge samples to be analyzed. Total analysis and leaching test were performed to find the characteristics of sewage sludge. The Nanjido sludge landfill site had the surface area of $50,000m^2$ and the average depth of 15m. The estimated sludge volume was 600,000ton. Sewage sludge in Nanjido sludge landfill site was very stable. Results of total analysis of heavy metals indicated that the sludge could be classified as a non-hazardous waste according to the California state regulation. The sludge also could be used as compost based on compost quality criteria of foreign countries. Results of Korea Extraction Procedure showed that sewage sludge in Nanjido sludge landfill site was not a hazardous waste.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.3
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• pp.141-147
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• 2021

The foreign trends of noncompliance occurring frequently in food contact materials during the period of 2011-2019 was investigated by analyzing the food safety risk information DB in the National Food Safety Information Service (NFSI). A total of 2,042 cases of noncompliance of food utensils, containers, and packages were classified into 5 violation categories; administrative procedures, manufacturing and processing standards, residues and migration standards, labeling and advertising, and quality standards. This was again subcategorized according to non-compliance causative factors. The non-compliances in residues and migration standards comprised the largest proportion (76.4%) of the violative categories. The number of noncompliance information collected in 2011 was 88 cases and increased to 373 cases in 2019. A 72.8% of the non-compliance case was identified to be products of 4 countries (China 64.2%, Germany 4.0%, Japan 3.2%, and Taiwan 3.1%), those produce large quantities of containers and packaging products. During the period of 2011-2019, the number of illegal use of hazardous materials and illegal recycling of waste synthetic resins has decreased to less than one a year since 2014. On the other hand, after 2016, inconsistency of heat-resisting temperature labeling (Taiwan), non-compliance in paper container's strength standards, violation of printing standards, and the risk of consumer injury while using the products were newly reported due to the strengthening of consumer safety protection regulations. Migration of hazardous substances in synthetic polymer products such as heavy metals, melamine and formaldehyde in melamine tableware, primary aromatic amines which are colorant components in kitchenware such as ladles and spatulas, and phthalate plasticizers have been continuously reported with high frequency.

• Analytical Science and Technology
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• v.22 no.1
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• pp.92-100
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• 2009

Azacrown resins were synthesized by mixing 1-aza-12-crown-4 macrocyclic ligand into styrene (2th petroleum in 4th class hazardous materials) divinylbenzene (DVB) copolymer with crosslinkage of 1%, 2%, 5% and 10% by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, thermogravimetric analysis (TGA), surface area (BET), and IR-spectroscopy. The effects of pH, time, crosslinkage of resins and dielectric constant of solvent on adsorption of metal ions by resin adsorbent were investigated. Metal ions showed a great adsorption over pH 3 and adsorption equilibrium of metal ions was about two hours. In addition, adsorptive selectivity of metals on the resin in ethanol solvent was increased in the order of ${UO_2}^{2+}$ > $Ca^{2+}$ > $Sm^{3+}$ ion and adsorption of uranium ion was decreased with increase of crosslinkage such as 1%, 2%, 5% and 10% and was inversely proportional to the order of dielectric constant of solvents.