• Journal of Korean Society of Forest Science
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• v.86 no.3
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• pp.324-333
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• 1997

The research has been made for the effects of the pollution by the abandoned coal mine drainage on the physical and chemical properties of soil, stream sediment and soil water. The soils overspreaded by the abandoned coal don't develop solum and the bulk density is $1.83g/m^3$, compared with $1.14-1.38g/m^3$ in the other forest soils. The soil pH range in coal bearing region ie, from 4.01 to 4.11 and non-coal bearing soil range is from 5.03 to 5.13. Heavy metals such as As, Cr, Ni, Mo and Ba of coal bearing soils and polluted stream sediments have larger concentration than those of non-coal content and non-polluted. Especially As and Mo concentrations are largely high in coal bearing. The relative ratios $K_2O/Na_2O$ of geochemical elements are higher in coal bearing soil and polluted stream sediments than those of non-coal bearing soils and non-polluted stream sediments as well as black shales of the Changri Formation. However, $MgO+Fe_2O_3+TiO_2/CaO+K_2O$ are the opposite trends, so that the ratios are lower in the polluted regions. The soil water pHs in the polluted regions are the strong acid(pH3.4-4.2) and buffer capacity of the polluted soil is low because canons such as $Na^+$, $K^+$, $Mg^{+2}$are leached by the acidification.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.4
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• pp.265-273
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• 2005

Chemical properties and heavy metal concentrations of forest soils of four abandoned coal mine lands affected by coal mining activities in the Mungyeong area were investigated to provide basic information for revegetation of abandoned coal mine lands. Soil pH in abandoned coal mine lands ranged from 5.30 to 6.76 it in the control site was 5.23. Contents of organic matter and total N in abandoned coal mine lands were $4.46\~7.19\%\;and\;0.07\~0.15\%$, respectively. Available P contents were 6.54 for A (Samchang), 6.52 for B (Bongmyeong),3.94 fur C (Kabjung), 5.45 mg/kg for D (Danbong coal mine land) and 5.25 mg/kg for the control site, which had a positive correlation with soil pH. Contents of exchangeable Ca, Mg, K and Na in abandoned coal mile lands averaged 196.1, 88.7, 88.2 and $10.2cmol^+/kg$, with a range of $132.1\~242.1,\;24.2\~138.\; 64.9\~120.8\;and\;8\~12.2cmol^+/kg$, respectively. Those of the control site were 192.8, 95.8, 104 and $21.2 cmol^+/kg$, respectively. Heavy metals such as Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn of forest soil in abandoned coal mine lands have a larger content than those of the control site. Al, Mn and fb content was especially high in abandoned coal mine lands. The Al content of forest soil in abandoned coal mine lands ranged from 397 to 917 ppm, which was considered to be high enough to inhibit tree growth. Therefore, it is suggested that soils of abandoned coal mine lands contaminated by mining activities need to be properly treated for remediation of environmental problems.

• Korean Journal of Environment and Ecology
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• v.22 no.3
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• pp.260-267
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• 2008

This study was carried out to investigated the relation between air depositions and soil properties in Gyeongsanman province. Soil pH was average 4.40 in regions, and was the highest soil pH value in Miryang-sanne(pH 5.02), the lowest pH value in Namhae-seomyeon(pH4.08). Soil pH, soil organic matter content, avail phosphorus, K, Ca and cation exchange capacity(CEC) were significantly different among regions(p<0.05). Pb in Heavy metal content was 3.86mg/kg average value, and was the highest in Keo-je region(9.87mg/kg), the lowest in Mryang-sanne (0.86mg/kg). Zn, Cd, Cr and Ni were significantly different among regions(p<0.05). Correlation between rainfall pH and soil properties were positive in soil $pH(r=0.7826^{**})$, Ca$(r=0.6278^*)$, Mg$(r=0.5841^*)$, CEC$(r=0.6341^{**})$ and Cd$(r=0.5995^*)$, and were negative in Pb$(r=-0.5283^*)$. Correlation between $SO_2$ concentration and soil properties was negative in soil pH$(r=-0.6796^{**})$, Ca$(r=-0.5810^*)$, Mg$(r=-0.5522^*)$) and CEC$(r=-0.5905^*)$. Correlation between $NO_2$ concentration and soil properties were positive in organic matter $(r=0.6208^*)$, K$(r=0.5380^*)$. It was predicted that rainfall and $SO_2$ concentration would affect soil acidification, and soil heavy metal content related Cd and Pb. Others soil heavy metal were not related.

• Journal of Life Science
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• v.24 no.4
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• pp.403-410
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• 2014

This study was conducted in organic certification soil for the comparison of heavy metals, nutrients, and irrigated water standards to certify a farm. It was carried out in 811 paddy fields of organic rice (Oryza sativa L.) cultivated at Goseong-Gun. The amounts of 8 heavy metals, Cd, Cu, As, Hg, Pb, $Cr^{6+}$, Zn, and Ni were found to be 0.05, 14.5, 1.08, 0.92, 10.7, 1.34, 35.9, and 22.2 mg $kg^{-1}$ in regular sequence in the organic paddy soil, and they were 0.32, 13.6, 1.01, 0.03, 10.4, 0.91, 42.4 and 22.5 mg $kg^{-1}$ in the non-pesticide paddy soil. In comparing organic and non-pesticide paddy soil with respect to the chemical characteristics of the soil, the average pH and the amount of organic matter, available phosphate and available silicate were 5.88 and 27.6 g $kg^{-1}$, 134.5 mg $kg^{-1}$, and 165.3 mg $kg^{-1}$, while they were 5.78 and 32.1 g $kg^{-1}$, 107.7 mg $kg^{-1}$, and 175.2 mg $kg^{-1}$, respectively. The amount of exchangeable cation $K^+$, $Ca^{2+}$, and $Mn^{2+}$ were 0.25, 5.20, and 1.04 cmol+ $kg^{-1}$ in organic paddy soil, while they were 0.38, 5.13, and 1.19 cmol+ $kg^{-1}$ in non-pesticide paddy soil. The pH, DO, BOD, COD and SS conditions of the irrigated water used in the organic paddy soil were found to be 7.23, 8.40, 2.80, 1.86, and 2.58 mg $l^{-1}$ and the condition of irrigated water used in the non-pesticide paddy soil were found to be 7.65, 9.16, 2.25, 4.11, and 4.00 mg $l^{-1}$, respectively. Based on these findings, we suggest that environmentally-friendly certificates in Korea have to unify organic and non-pesticide agro-products in an organic standard in food policy and control because there is no difference between soil and irrigated water standards in the two certifications.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.4
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• pp.31-39
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• 2017

From July to August 2013, liquid fertilizers produced at 180 liquid manure public resource centers and liquid fertilizer distribution centers were collected. The maturity of liquid fertilizers was measured using the mechanical maturity measurement device. The nutrient contents (nitrogen, phosphorus, and potassium), physicochemical properties, and heavy metal content of 46 liquid fertilizers were investigated in this study. We used a matured liquid fertilizer with a total number of 46, with number of 7 for Gyeonggi-do, 3 for Chungcheongbuk-do, 2 for Chungcheongnam-do, 13 for Jeollabuk-do, 5 for Jeollanam-do, 3 for Gyeongsangbuk-do, 11 for Gyeongsangnam-do, 1 for Daejeon, and 1 for Jeju-do. The physicochemical properties were as follows: pH 8.0, EC 11.6 mS/cm, SS 5,188 mg/L, TKN 847mg/L, ${{NH_4}^+}-N$ 317 mg/L, ${{NO_3}^-}-N$ 170 mg/L, Org-N 360 mg/L, TP 193 mg/L, and TK 2,557 mg/L. The total amount of NPK was 3,596 mg/L. The total amount of N-P-K was as follows: a number of 2 at 1,000-2,000 mg/L (4%), a number of 17 at 2,000-3,000mg/L (37%), a number of 11 at 3,000-4,000mg/L (24%), and a number of 16 at 4,000mg/L or more (35%). Thus, 41% of the mature liquid fertilizers were below the official standard of commercial fertilizer (livestock manure liquid fertilizer) (0.3% of the total amount of N-P-K). Most of the N-P-K total amount showed non-uniform characteristics of low nitrogen and low phosphoric acid due to the potassium concentration. The average heavy metal content in the matured liquid fertilizer was as follows: As, not detected; Cd, 0.01 mg/kg; Hg, not detected; Pb, 0.02 mg/kg; Cr, 0.14 mg/kg; Cu, 6.89 mg/kg; Ni, 0.44 mg/kg; and Zn, 20.70 mg/kg. Thus, the official standard of commercial fertilizer was satisfied in all categories, indicating a safe level.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.2
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• pp.335-348
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• 1996

Retention is one of the major factors deciding the success and longevity of resin bonded restorations. The purpose of this study was to find a better resin cement and metal surface treatment method that would enhance the bonding strength. The bonding surfaces of Verabond, one of Ni-Cr-Be alloys, were treated with sandblasting(Group 1), sandblasting and EZ-Oxisor(Group 2), sandblasting and silicoating(Group 3), and than thay were bonded with All-Bond C & B, Panavia 21, Superbond C & B. The specimens were thermocycled, and the tensile bond strength was measured using the unive-rsal testing machine. Also the mode of bond failure was observed. The results were as folows. 1. The Superbond C & B showed the highest bond strength among the three resin cements and decreased in the order of Panavia 21, All-Bond C & B. There was significant differe-nce among them(p<0.05). 2. Group 3 showed the highest bond strength among the three metal surface treatment methods, and there was significant difference compared with Group 1 and Group 2(p<0.05). But there was no significant difference between Group 1 and Group 2. 3. Observing the mode of bond failure, Superbond C & B and Panavia 21 showed mostly cohesive failure in all groups. All-Bond C & B showed all types of bond failure in Group 3, but Group 1 and Group 2 showed only adhesive failure. 4. According to the results of this study, the silicoating method and 4-META containing resin cement were considered to be more acceptable for resin bonded restoration.

• The Journal of Advanced Prosthodontics
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• v.4 no.2
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• pp.89-92
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• 2012

PURPOSE. Adequate passive-fitting of one-piece cast 3-element implant-supported frameworks is hard to achieve. This short communication aims to present an alternative method for section of one-piece cast frameworks and for casting implant-supported frameworks. MATERIALS AND METHODS. Three-unit implant-supported nickel-chromium (Ni-Cr) frameworks were tested for vertical misfit (n = 6). The frameworks were cast as one-piece (Group A) and later transversally sectioned through a diagonal axis (Group B) and compared to frameworks that were cast diagonally separated (Group C). All separated frameworks were laser welded. Only one side of the frameworks was screwed. RESULTS. The results on the tightened side were significantly lower in Group C ($6.43{\pm}3.24{\mu}m$) when compared to Groups A ($16.50{\pm}7.55{\mu}m$) and B ($16.27{\pm}1.71{\mu}m$) ($P$ <.05). On the opposite side, the diagonal section of the one-piece castings for laser welding showed significant improvement in the levels of misfit of the frameworks (Group A, $58.66{\pm}14.30{\mu}m$; Group B, $39.48{\pm}12.03{\mu}m$; Group C, $23.13{\pm}8.24{\mu}m$) ($P$ <.05). CONCLUSION. Casting diagonally sectioned frameworks lowers the misfit levels. Lower misfit levels for the frameworks can be achieved by diagonally sectioning one-piece frameworks.

• Ocean and Polar Research
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• v.25 no.1
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• pp.21-30
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• 2003

Seasonal fluctuations of physico-chemical and biological aspects of the environment were studied in Vladivostok harbour (Golden Horn Bay, the East Sea/Sea of Japan). The benthic community structure was described with a focus on size-spectra (bacteria, meio- and macrofauna) related with the chemical environment and chemical fluxes in sediment and to reveal their possible ecological role in the process of bioremediation of the environment. Samples from two sites with different concentrations of heavy metals (Fe, Zn, Cu, Pb, Mn, Cr, Ni Cd, Co) and petroleum hydrocarbon were assessed by a number of methods. These included plate counts of culturable bacteria, observation through a scanning electron (SEM) and transmission electron microscope (TEM). These approaches were complemented with microscopic assessments of the diversity of the benthic community. The specific communities had a limited number of species, tolerant to abnormally high levels of toxic compounds. The dominant species were presented by several sho.1-lived small polychaetes (Capitella capitata) and nematodes (Oncholaimium ramosum). The highest population density was recorded in microbenthos, in various diatoms, various physiological groups of bacteria which participate in biomineralization: marine heterotrophic bacteria, which oxidized oil, black oil in addition to groups resistant to heavy metals. They have the entire set of mechanisms for neutralizing the negative effect of those compounds, forming the detrital food web and biogeochemical circulation of material in sediments, which results in the biological self-recycling of sea basins. Macro- and meiobenthic organisms were more sensitive to a greater extent of $H_2S$ and petroleum hydrocarbons than to metal content, but the within-site rankings were the same as those achieved for microbiological analyses.

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.79-86
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• 2008

The purpose of this study was to investigate the effect retention element formed by metal surface treatment method on the bond strength of indirect composite resin and metal. The metal specimens were cast from Ni-Cr alloy($Rexillium^{(R)}$ III). They were divided into 5 groups by applied retention element: $50{\mu}m$ aluminium oxide sandblasting group, $250{\mu}m$ aluminium oxide sandblasting group, 0.2mm retention crystal group, 10% $H_{2}SO_{4}$ solution etching group, $110{\mu}m$ $Rocatec^{TM}$ Plus system group. Total 50 metal specimens were veneered with Sinfony indirect composite resin system. Specimens were tested for shear bond strength on an Instron universal testing machine and fracture mode of fractured specimens were analyzed by SEM and EDS. 1. 0.2 mm retention crystals were most effective in improving the resin-metal shear bond strength (p<0.05). 2. Sandblasting by $250{\mu}m$ aluminium oxide were more effective than sandblasting by $50{\mu}m$ aluminium oxide in improving the resin-metal shear bond strength(p<0.05). 3. Fracture mode of resin-metal fractured surface were cohesive failure mode in 0.2mm retention crystal, mixed failure mode in sandblasted specimens, etched specimens and the specimens sandblasted with $110{\mu}m$ $Rocatec^{TM}$ Plus system.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.85-101
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• 1991

The purpose of this study was to determine the optimum range of laser energy density to the enamel surface of permanent incisors when they are irradiated with the pulsed Nd : YAG laser, Laser impacts on each experimental group were made at energy density of $20\sim50J/cm^2$ by 20 pulses of the pulse width 1.2 msec. The author investigated the enamel surface with the sunning electron microscope(SEM) and the surface roughness tester, and measured the shear bond strength between electrolytically etched Ni-Cr-Be alloy casting and composite resin. The obtained results were as follows: 1. The surface roughness of enamel after laser irradiation showed the significant difference level from the energy density $40J/cm^2(P<0.05)$. 2. The mean shear bond strength of etched-metal resin-bonded specimens were $154.23{\pm}33.30kg/cm^2$ at unlased enamel surface and $195.72{\pm}29.56kg/cm^2$ at lased energy density $30J/cm^2$, and showed a significant difference(P<0.05). 8. SEM photographs showed the irregular microcracks and the structural changes of lased enamel surface. 4. SEM photographs of the fracture surface after testing the shear bond strength showed the aspect of interfacial fracture between bonding agent and composite resin at the metal sides.