• Economic and Environmental Geology
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• v.34 no.5
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• pp.461-470
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• 2001

The Shihung mine was restored in the early 90's after abandonment for 20 yews since 1973. Although disposed mine tailings were removed and the site was replaced by an incineration plant, still some residual mine tailings remain in the places including the old mine tailing ditposal area and the adjacent agricultural area. These residual mine tailings are prone to impose an adverse impact on the soil and groundwater and needs investigation for the potential contamination. Mine tailing samples were collected from the old tailing disposal area and the iii paddy. The porewater from the mine tailing were extracted and analysed to investigate chemical changes along the reaction path. Batch leaching tests were also carried out in the laboratory to find any supporting evidence found in the field analysis. Evidence of elemental leaching was confirmed both by the mine tailing and the porewater chemistry in them. The element concentrations of Cu, Cd, Pb, Zn in the porewater exceed the standard for drinking water of Korean government and US EPA. Leaching of heavy metals from the mine tailing seem to be responsible for the contamination. In batch leaching test. heavy metals were either continuous1y released or declined rapidly. Combining the information with porewater variation with depths and the geochemical meodeling results, most of elements are controlled by dissolution and/or precipitation processes, with some solubility controlling solid phases (Cu, Pb, Fe and Zn). Batch leaching test conducted at fixed pH 4 showed much higher releases for the heavy metals up to 400 times (Zn) and this area is becoming more vulnerable to soil and groundwater pollution as precipitation pH shifts to acidic condition.

• Journal of Conservation Science
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• v.32 no.3
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• pp.377-384
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• 2016

There are physical and chemical method for removement of a lacquered layer existing on the surface when gilding an iron Buddha, these caused environmental pollution by surface degradation and is very noxious for conservation scientist's health. Thus, on this study, we conducted a lacquered layer removement experiments using Nd:YAG Laser which is contactless and eco-friendly. Specimens were made by polishing $5{\times}5$ size of iron(99.9%) specimens surfaces evenly and by differing of number of coating of unrefined lacquer, so there were thickness differences of $10{\mu}m$, $20{\mu}m$, and $30{\mu}m$. The laser machine used in this study was Nd:YAG Laser, and we used two wavelength modes; 1064 nm(160~180 mJ) for infrared light region and 532 nm(50~350 mJ) for ultraviolet light region. The experiment done by investigating the transition of specimens' surfaces with laser wavelength, energy, and numbers of investigation. The remain amount of lacquered layer surfaces before/after laser irradiation was investigated by stereoscopic microscope, observation by SEM, Non-contact Surface Roughness Measurement Device, and FT-IR etc. As a result of each analysis, we could verify the thickness of $10{\mu}m$, $20{\mu}m$ of lacquered layer removed without surface degradation when using 1064 nm wavelength with $1.0J/cm^2$ density. We could find out that Nd:YAG Laser is effective for removing remained lacquered layers when gilding an iron Buddha. In the future, when not only the metal has made various studies also wood lacquered furniture or the like, it seems to be utilized to remove the lacquer without surface damage.

• Korean Journal of Food Science and Technology
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• v.39 no.3
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• pp.255-259
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• 2007

For this investigation, we analyzed the chemical characteristics and enzyme activities of Icheon Ge-Geol radish, Gangwha turnip, and Korean radish. Regarding their proximate compositions, the water contents of the Icheon Ge-Geol radish, Gangwha turnip, and Korean radish were 87.78, 92.73, and 91.45%, respectively. The crude protein, crude fiber, and ash contents of the Icheon Ge-Geol radish were 1.35, 1.11, and 1.55%, respectively, which were much higher than the contents of the other samples; however, total dietary fiber was significantly lower. For mineral content, the magnesium, potassium, and calcium levels of the Icheon Ge-Geol radish were higher than the other samples. With regards to the enzyme activities of the samples, the protease and myrosinase activities of the Icheon Ge-Geol radish were higher than in the other samples. For ${\alpha}-amylase$ activity, the Korean radish showed the strongest activity (18.99 units/g of sample), followed by the Gangwha turnip and Icheon Ge-Geol radish.

• Journal of Conservation Science
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• v.31 no.4
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• pp.361-372
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• 2015

The experiment attempts to find out the effect of the mixture of the antimicrobial agent and insecticide on metallic material including Silver(99.9%), Copper(99.9%), Lead(99.9%) and Iron(99.5%) by Oddy test. The mixtures of the antimicrobial agent and insecticide were prepared in 60ml; with the standard concentration of 17.5% in B77 Essential oil mixture, one for mixture of concentration of ${\pm}1{\sim}2%$ and insect repellent material; the other for mixture of low concentration and antimicrobial agent(BS-2 and BS-3) material. After Oddy test, we investigated the variation in the surface of the samples by visual inspection, weighing, color measurement and SEM-EDS analysis. The result showed that Lead had the biggest change in the surface, and Copper had the biggest change in the color. In addition, changes in the samples before and after the experiment were found to be greatest at concentration of 19% of Essential oil mixture of the antimicrobial agent and insecticide. Also, B78 Essential oil mixture produce change in samples. It means when the concentration of oil mixture rises, the variation of the samples gets bigger. And, the low concentration of mixture including B77 Essential oil mixture and B78 Essential oil mixture also produce big change in the samples. However, the low concentration of B77 Essential oil mixture that do not contain B78 Essential oil mixture was able to confirm that the change of the surface is not large.

• Applied Biological Chemistry
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• v.42 no.4
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• pp.351-355
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• 1999

In order to find anti-dementia drugs from natural products, prolyl endopeptidase inhibitors were purified from Puerariae Flos by consecutive solvent partition, followed by silica gel, Sephadex LH-20, and HPLC. Four isoflavonoid inhibitors were isolated and identified as tectorigenin, genistein, 5,7-dihydroxy-4',6-dimethoxyisoflavone, and 5-hydroxy-6,7,4'-trimethoxyisoflavone by means of instrumental analyses including $^{1}H-$, $^{13}C-$, $^{2}D-NMR$ and MS and $IC_{50}$ values against PEP were 5.30 ppm$(17.7\;{\mu}M)$, 10.39 ppm$(38.5\;{\mu}M)$, 13.92 ppm$(44.3\;{\mu}M)$, and 20.61 ppm$(62.8\;{\mu}M)$, respectively. Some previous mistakes in $^{13}C-NMR$ assignment were revised by careful investigation of HMBC and HMQC data.

• Journal of Nutrition and Health
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• v.31 no.1
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• pp.36-45
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• 1998

Dietary and other factors affecting bone density of 32 Korean healthy college women aged 19-23 years were assessed. Data for food and nutrient intake was obtained by a semiquantitiative food frequency questionnaire. Serum samples were anlayzed for total Ca, P, Ca++, PTH, calcitonin and 25-hydroxycholecalciferol , (25-OH-Vit D3) and BMDs of lumbar spine(L2-L4), femoral neck(FN), ward's triangle (WT) and trochanter(TR) were measured by an XR-series X-ray bone densitometer. Relationships between the factors and BMDs were analyzed by stepwise multiple regression analysis and Pearson's correlation coefficient(r). The results are summarized as follows. Mean daily intake of energy(86.1%), Ca(74.3%), vitamin A (53.75), Fe(49.75) and vitamin B$_2$(86.6%) were lower while other notrients incuding P(126%) were higher than the Korean RDA. The BMDs of lumbar spines and femurs ranged from 0.73g/$\textrm{cm}^2$ to 1.23g/$\textrm{cm}^2$and 0.48g/$\textrm{cm}^2$ to 1.04g/$\textrm{cm}^2$, respectively. Both protein and P intakes were inversely associated with serum total Ca. Furthermore, Ca intake as well as Ca/P ratio (Ca/P) were inversely associated with serum ionized Ca(Ca++) concentration. The intakes of protein P and Ca , however, were not significantly associated with the BMDs measured in this study. There were little association between BMDs and alcoholic beverage or caffeine consumption. The only significant association detected was a positive relationship between caffeine consumption and BMD of WT. It seemed to be noticeable that BMDs of L2-L$_4$, FN and WT were significantly inversely associated with serum P concentration. However, there was no significant association between BMDs and the levels of total Ca to Ca++ in serum. Body weight was positively associated with BMD of lumbar spine and BMI was also positively associated with BMDs of FN and WT. The subjects who had an early menarche appeared to have higher BMDs than those who had had a late mearche. According to stepwise multiple regression analysis. Menarche and BMI were stronger determinants of BMDs in the young women than was diet. P intake appeared to be a more potent dietary determinant than Ca intake. The three factors, menarche, BMI , and P intake , additionally accounted for 24% and 378% of the variance in BMDs of FN and L$_2$-L$_4$, respectively. Further investigation is necessary to determine the factors needed to increase serum P level which negatively affects. BMD in young Korean college women.

• Journal of Korean Society of Steel Construction
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• v.27 no.3
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• pp.323-332
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• 2015

Special concentrically braced frames(SCBFs) have distinctive advantages in considerable seismic performance, which make engineers widely use SCBFs as lateral-load resisting systems in buildings and have researchers to develop SCBFs design methods. Compared to the extensive research of SCBF, comparatively little information is currently available on the performance of SCBFs designed and constructed before the early 1990's. Prior to 1988, concentrically braced frames(CBFs) design requirements were substantially less restrictive. As a result, many existing structures designed to these requirements may not ensure ductility and pose a significant concern in current buildings. In this study, these older frames are referred as non-seismic braced frames(NCBFs). In order to investigate the seismic behavior of NCBFs, finite-element(FE) models of SCBF and NCBF were suggested and verified using case investigation of NCBF conducted on the University of Washington. Using these models, the seismic behavior of NCBF with shared welding shear tab, which is the representative of the types of connections, was established and compared with the seismic performance of SCBF.

• Tunnel and Underground Space
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• v.28 no.1
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• pp.59-71
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• 2018

Since the generalized Hoek-Brown (GHB) function predicts the strength of the jointed rock mass in a systematic manner by use of GSI index, it is widely used in rock engineering practices. In this study, a series of 2D elasto-plastic FE analysis, which adopts the GHB criterion as a yield function, was carried out to investigate the radial convergence characteristics of circular tunnel excavated in the GHB rock mass. The effect of the plastic potential function on the elasto-plastic displacement was also examined. In the analysis, the wide range of both the $K(={\sigma}_h/{\sigma}_v)$ and GSI values are considered. For each K value, the variation of the ratio of sidewall displacement to roof displacement was calculated with varying GSI values and the obtained displacement patterns were analysed. The calculation results show that the displacement ratio significantly depends not only on the K value but also on the range of GSI value. In particular, for lower range of GSI value, the displacement ratio pattern calculated in the elasto-plastic regime is opposite to that predicted by the elasticity theory. In addition, the variation of the radial displacement ratio with GSI value for different types of plastic potential function showed similar trend.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.131-136
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• 2017

Automobile engine oil is the most important lubricant for operating as the engine is started. Recently, manufacturers of the automotive industry and lubricants are considerably improving the quality of oil with additive to extend change cycle period. Most customers are recommended genuine oil among different types from shop expert. Through this report we suggest another reference point for consumer to pick highly efficient lubricant. This report is investigated oil compounds to compare with 6 different automotive considering actual running condition for 7 months. we conducted experiment from physical and chemical perspectives. In the field, through various experiments oil compounds between mineral oil and synthetic oil are largely distinguished in oxidation, viscosity, fluid and TBN. These are influenced by engine part wear as piston, bearing etc. Comparing various investigation with different oil the performance of synthetic oil is shown better condition in flash point, oxidation stability and also found less in change pollutant iron, Al compounds. Additives of oil show clear difference Ca level in detergent-dispersant both mineral oil and synthetic oil. And Zn in extreme pressure additives and P in Lubricity improver make no difference to both.

• Korean Journal of Materials Research
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• v.22 no.11
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• pp.569-574
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• 2012

Large single grain $Gd_{1.5}Ba_2Cu_3O_{7-y}$ (Gd1.5) bulk superconductors were fabricated by a top-seeded melt growth (TSMG) process using an $NdBa_2Cu_3O_{7-y}$ seed. The seeded Gd1.5 powder compacts with a diameter of 50 mm were subjected to the heating cycles of a TSMG process. After the TSMG process, the diameter of the single grain Gd1.5 compact was reduced to 43 mm owing to the volume contraction during the heat treatment. The superconducting transition temperature ($T_c$) of the top surface of the single grain Gd1.5 sample was as high as 93.5 K. The critical current densities ($J_cs$) at 77 K and 1T and 1.5 T were in ranges of 25,200-43,900 $A/cm^2$ and 10,000-23,000 $A/cm^2$, respectively. The maximum attractive force at 77 K of the sample field-cooled using an Nd-B-Fe permanent magnet (surface magnetic field of 0. 527 T) was 108.3 N; the maximum repulsive force of the zero field-cooled sample was 262 N. The magnetic flux density of the sample field-cooled at 77 K was 0.311T, which is approximately 85% of the applied magnetic field of 0.375 T. Microstructure investigation showed that many $Gd_2BaCuO_5$ (Gd211) particles of a few ${\mu}m$ in size, which are flux pinning sites of Gd123, were trapped within the $GdBa_2Cu_3O_{7-y}$ (Gd123) grain; unreacted $Ba_3Cu_5O_8$ liquid and Gd211 particles were present near the edge regions of the single grain Gd1.5 bulk compact.