• Korean Journal of Soil Science and Fertilizer
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• v.48 no.6
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• pp.666-670
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• 2015

Competition among anion species in solution for same sorption sites and soil surface can be of major significance in determining the effective mobility of any potentially adsorbing species. Major soil anion species include $OH^-$, $F^-$, $Cl^-$, $HCO_3{^-}$, $CO_3{^-}$, $NO_3{^-}$, $SO_4{^{2-}}$, and $PO_4{^{3-}}$. And some micro nutrients such as boron and molybdenum exist as $H_2BO_3{^-}$ and $MoO_4{^{2-}}$, as do some heavy metals such as chrome and arsenic as $CrO_4{^{2-}}$ and $HAsO_4{^{2-}}$. Pesticides such as 2,4,5-T and 2,4-D also exist as anions. Many anion species are retained by more complex mechanisms than the simple electrostatic attractions involved in most cation adsorption reactions. In binary system composed of two anions, the adsorption of one anion is influenced by the other anion due to the competition for the available and limited binding sites in soil constituents. The specifically adsorbed anions may compete more effectively for sorption sites than that of nonspecifically adsorbed anion. In this study, we aim to evaluate the mathematical models to determine the magnitude of concentration variations in adsorption due to competitive interactions between anions introduced to a system in binary mixtures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.61-67
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• 2017

Research into the selection of suitable materials and the development of fast processing methods for press die manufacturing is absolutely necessary to reduce the production time and cost. In particular, knowledge of its heat properties must be considered whendeveloping a long press die. Generally, as the main component materials of press dies, Cr, W low alloy tool steel, high carbon-high chrome steel, high speed steel, etc., are used as thetooling steel for the cold die. Machine tools and wire-cut electric discharge machining are mainly used for processing the press die parts. There are many differences in the machining time and life cycle of die parts depending on the machining process. The parts produced by milling and grinding have a high manufacturing time and cost with a long life cycle, while thosemade by milling and wire-cut discharge machining have areduced manufacturing time and cost,whereastheir die life cycle is reduced. Therefore, in this study, we will discuss amethod of improving the life cycle of the die parts by using heat treatment as a processing method that reduces the manufacturing time and cost. SEM, EDS analysis and the surface roughness analysis of the surface and center of the workpiece are used for analyzing the specimens produced by three machining methods, viz. milling - grinding, milling - wire cut discharge, and milling - wire cut discharge - heat treatment. A method of making die parts having the same life cycle as those produced by milling - grinding is developed with the milling - wire cut discharge - high temperature tempering method.

• Journal of Environmental Health Sciences
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• v.36 no.6
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• pp.480-495
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• 2010

This study evaluated the distribution of the concentrations of nano-particles and heavy metals (08-Pb, Cr, Zn, As, Fe, 09-Pb, Cr, Zn, Cu, Ni, Mn) in Seoul, Chungnam A and Gwangyang from August to December, in 2008 5 times each in the Seoul area, 5 times in and Chungnam A area and from August to November, in 2009 14 times in the Chungnam A area, 8 times in the Gwangyang area. The examined results showed high concentration level from $PM_1$ through $PM_{0.1}$ in all three areas. These results were obtained the concentration of particles by diameter and statistically significant in Stage5 (1.0-0.56 ${\mu}m$) from the result of conducting Kruskal-Wallis H test (p < 0.05). In the case of the heavy metal concentration included in 0.10-0.056 ${\mu}m$, 0.056 ${\mu}m$, the lead concentration of Chungnam Asan area was 6.49 ng/$m^3$ and 9.93 ng/$m^3$, which was higher than 3.05 ng/$m^3$ and 4.22 ng/$m^3$ of Seoul, respectively. The concentration of iron in Seoul was 9.28 ng/$m^3$ and 13.24 ng/$m^3$, that appeared higher than 2.38 ng/$m^3$ and 3.23 ng/$m^3$ of Chungnam A area, respectively. The concentration level was similar to other metals except lead and iron in Chungnam A area and Seoul. From the concentration of heavy metal included in 0.10-0.056 ${\mu}m$, 0.056 ${\mu}m$, the lead concentration of Chungnam A area was 0.31 ng/$m^3$ and 0.12 ng/$m^3$ while Gwangyang was 0.28 ng/$m^3$, 0.06 ng/$m^3$. Thus Chungnam A area showed higher lead concentration than Gwangyang. The manganese concentration of Chungnam A area was 0.12 ng/$m^3$ and 0.03 ng/$m^3$ while Gwangyang was 0.21 ng/$m^3$ and 0.08 ng/$m^3$. Therefore, the concentration of Gwangyang appeared higher than that of Chunnam A area. These two metals showed statistically significant in 0.056 ${\mu}m$ (p < 0.05, p < 0.01). Among the concentration of heavy metal in all regions, the result demonstrated that the order of higher concentration is arsenic > iron > zinc > chrome > lead > nickel > copper > manganese.

• Journal of the Korean Wood Science and Technology
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• v.46 no.5
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• pp.449-470
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• 2018

A review of research trends on wood surface protection for exterior use obtained the following conclusions: It has been reported that inorganic compounds such as chrome and copper used as wood preservatives can protect wood from weathering. It has been shown that precoating with hydrophobic substances such as wax and oil, UV absorbers, and HALS (Hindered Amine Light Stabilizers) enhances weathering resistance on the surface of ACQ-treated wood. Opaque coatings of paint/stains and semitransparent stains on the surface of preservative treated wood can increase the synergistic effects on prevention of weathering deterioration. Also the need for repainting periodically for the protection of the preservative treated wood surface has also been suggested. ZnO or $TiO_2$ of fine particles, metal ions such as Co, Cr, Fe, Mn, Ni and Ti, and UV absorbers such as tris-resorcinol triazine derivatives, triazine and benzotriazole were introduced as additives for preventing UV in the transparent coating on wood. Several reports showed that chemical modification such as methylation, acetylation, or alkylations have made some increases the effects of preventing weathering with the increasing weight gain of chemical formulas. In heat-treated wood, there were various contradictory reports on the resistance of weathering, and there were some other reports emphasizing the necessity of painting with UV resistance, which leads to the necessity of more advanced studies.

• Journal of Conservation Science
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• v.36 no.5
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• pp.383-392
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• 2020

This study aimed to examine the characteristics of paint used for modern art works by conducting sectional observations, inorganic component analysis, and infrared spectroscopic analysis on the painted layers of 3 painted sculpture works exhibited in the Yongdam Dam Environmental Sculpture Park and Naejangsan Sculpture Park in the Jeollabuk-do area. The observations indicate that the cross section is composed of various layers of 2-3 folds, the thickness of the layers was uneven at approximately 23-150 ㎛, and putty was used for plate treatment prior to painting. Inorganic component analysis results show that putty containing calcium carbonate, iron oxide, diatomite, and titanium dioxide was used for the putty layer. It is also assumed that paint mixed with green (Cr₂O₃), blue(sodaliteblue), red(chromered), andwhite(TiO₂) colors were used for the painted layers. As a result of infrared spectroscopic analysis to confirm the types of paint, it is estimated that the paint was mixed with polyester resin and an extender.

• Journal of Mushroom
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• v.3 no.4
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• pp.145-153
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• 2005

Two hundred seventy-four microorganisms were isolated from the soil of abandoned mines around for selecting the heavy metal-degrading strains and their microbial diversity was analyzed. The specimens of macrofungi were isolated from the soil of abandoned mines around for selecting the heavy metal-degrading strains. Eunseong and Dogok in Gyeongsangbuk-do, for selecting the heavy metal-degrading strains. Soil was also collected from same location. Contents of heavy metals (Cd, Cu, Pb, Zn, Ni, Cr, and As) were determined spectrometically in fruiting bodies of forty eight wild macrofungi specimens with soils. When the analysed their transfer factor from soil to fruiting body, Amanita volvata have the highest transfer factor of cadmium and arsenic. And Mycena pura showed the highest in mercury, Marasmius pulcherripes in zinc, Laccaria laccata in nickel, and Collybia confluens in chrome. When compare the population of mushrooms between the contaminated mines and Mt. Chiak as the healthy area, Genus Russula and Collybia were collected both area, but Leucocoprinus, Coprinus, Suillus, Lepiost, Gyroporus, Lepista, Microstoma, Stropharia, and Agrocybe were only in the contaminated mine area.

• Journal of Environmental Health Sciences
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• v.44 no.1
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• pp.55-62
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• 2018

Objectives: This study set out to measure the heavy metal concentrations in waste water produced in the casting pickling process at dental technical laboratories and examine the actual state of its treatment. Methods:The investigator measured the concentrations of each heavy metal at 55 dental technical laboratories using an inductively coupled plasma optical emission system. Results: The annual usage of electrolytes was under 10 L in 50 (90.9%), and was 10L or more in five (9.1%) laboratories. Among the laboratories, 15 (27.3%) commissioned the treatment of waste,12 (21.8%) treated the waste with general sewage,and 28 (50.9%) treated the waste in aseptic tank. The arithmetic $mean{\pm}standard$ deviation and the geometric mean of chrome(Cr) were $75.3{\pm}50.9$ and 58.3 mg/L; those of cobalt (Co) were $112.3{\pm}106.7$ and 66.1 mg/L; those of nickel (Ni) were $62.9{\pm}83.5$ and 8.9 mg/L; those of molybdenum (Mo) were $17.1{\pm}13.4$ and 12.0 mg/L; those of iron (Fe) were $31.5{\pm}44.1$ and 6.2 mg/L; those of lead (Pb) were $0.3{\pm}0.3$ and 0.3 mg/L; those of beryllium (Be) were $3.6{\pm}3.6$ and 2.0 mg/L. The hydrogen ion concentration was under pH 2 across all the samples. Conclusions: The findings show that the dental technical laboratories were not doing well with the separation, storage, collection, and treatment of the electrolytes they discarded, and that most of the electrolytes were introduced through the general sewage or aseptic tank. The causes of this include alack of perception among the practitioners at dental technical laboratories and contracted companies avoiding collection for economic reasons. There is a need for education to improve the perceptions of waste water treatment among the practitioners at dental technical laboratories. Environment-related departments should be stricter with legal applications in the central and local governments. It is also required to provide proper management of commissioned treatment.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.2
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• pp.61-66
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• 2020

Recently, a variety of electric anesthetics devices have been developed and used in clinical practice to reduce the fatigue of the operator during local anesthesia for dental procedures and to compensate for the disadvantages of manual anesthesia device. In this electric anesthesia injection device, the accurate and constant delivery of pressure for drug infusion is a very important performance factor. In order to evaluate the accuracy of the transfer pressure, a small pressure gauge using a load cell is often used, but since the elastic body inside the load cell may not be able to accommodate a sufficient displacement, an error may occur when evaluating pressure performance. For these reasons, in this study, we proposed and evaluated a silicon-chrome steel (Si-Cr steel) spring jig that can accommodate relatively large displacements that can be used when evaluating the performance of a pressure-controlled pressure application device using a load cell type pressure gauge. As a result of the pressure transmissibility test and repeated measurement results using a commercial dental anesthesia injection device, a more stable result was obtained when using a spring jig, and it was confirmed that the frequency of abnormally high measurement was reduced.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.12
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• pp.1873-1879
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• 2010

This study was conducted to estimate the heavy metal contents of vegetables available on the markets in Seoul area. Concentrations of mercury (Hg), lead (Pb), cadmium (Cd), arsenic (As), chrome (Cr), nickel (Ni), copper (Cu), and zinc (Zn) were measured in 300 samples using a mercury analyzer and inductively coupled plasma optical emission spectrometer (ICP-OES) after wet digestion. The average values of heavy metals in vegetables were as follows [mean (minimum~maximum), mg/kg]; Hg: 0.0005 (N.D~0.007), Pb: 0.011 (N.D~0.259), Cd: 0.012 (N.D~0.188), As: 0.002 (N.D~0.142), Cr: 0.100 (0.019~0.954), Ni: 0.093 (0.003~1.231), Cu: 1.098 (0.072~36.29), and Zn: 3.48 (0.485~21.31). The heavy metal contents of vegetables available on the markets in Seoul were almost the same as or lower than those reported in other studies. The weekly average intakes of mercury, lead and cadmium from vegetables take 0.44~7.71% of PTWI (Provisional Tolerable Weekly Intakes) that the FAO/WHO Joint Food Additive and Contaminants Committee sets for evaluation of food safety.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.1
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• pp.129-135
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• 2012

This study was to investigate the heavy metal content of 55 commercial salts in the Seoul area. There were 22 types of solar sea salt, 17 types of processed salt and 16 types of reworked salt. Looked at another way, there were 22 types of domestic salt and 33 types of salt imported from France, the U.S., Japan, Australia, New Zealand, and Argentina. The samples were measured using both a mercury analyzer and an Inductively-Coupled Plasma Optical Emission Spectrometer (ICP-OES). The average heavy metal contents for commercial salts were Pb $0.281{\pm}0.344$, Cd $0.035{\pm}0.221$, Cr $0.364{\pm}0.635$, Cu $0.182{\pm}0.313$, As $0.046{\pm}0.062$, Ni $0.155{\pm}0.247$, Al $5.753{\pm}10.746$, Co $0.028{\pm}0.211$ and Hg $0.001{\pm}0.001$ mg/kg. The leads were detected highly in solar sea salt rather than in processed salt or reworked salt. Also chrome, arsenic and nickel were found more in processed salt. There were large differences in aluminum content between imported solar sea salt and processed salt. Aluminum was highly detected in French products, showing that salt can be affected by regional differences. The weekly average intakes of Pb, Cd, Cr, Cu, and Hg from commercial salt were 1.652% (0.000~6.754), 0.372% (0.000~7.214), 3.177% (0.000~26.279), 0.008% (0.001~0.049), and 0.031% (0.000~0.094) respectively compared with Provisional Tolerable Weekly Intakes established by the Joint FAO/WHO Expert Committee for the evaluation of food safety. The content of heavy metals from commercial salts was determined to be at safe levels.