• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.298-302
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• 2008

This study was carried out to evaluate brazing characteristics of the braze joint between superhard alloy particles and carbon steel. Two types of insert metals that made by mechanical alloying process were selected for this study. One is composed of Cu, Zn and Ag(MIM-1) and the other one is composed of Cu, Zn, Ag and Cd.(MIM-2) The chemical compositions of these insert metals were similar to AWS BAg-20 and BAg-2a system. And the commercial insert metals(CIM-1, CIM-2) were also evaluated for the comparative study. The characterization of the insert metals were conducted by wettability tests, shear tensile test and microstructural analyses. The results indicated that wettability tests displayed that MIM-1 and CIM-1 insert metals had the larger wetting angle than MIM-2 and CIM-2 and the wetting angle of the MIM-1 showed higher value than that of CIM-1. However these values are less than $25^{\circ}$ that is recommended for standard value for usual insert metals. The highest value of shear tensile tests was obtained from the brazed joint that made by MIN-1 and the value was $2.29{\times}10^2MPa$. This value is appeared to be higher or same as the commercial insert metals. The microstructures of the inserts metals were composed of Cu-rich proeutectic structure for matrix and Ag-rich eutectic structure. The braze joint between superhard alloy particles and carbon steel produced by the MIM-1(Ag-Cu-Zn) system showed sound joint showing stable microstructures. However there was also some porosities at the interface.

• Journal of the Mineralogical Society of Korea
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• v.18 no.2
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• pp.127-134
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• 2005

Although the bulk composition of materials is one of the major considerations in extractive metallurgy and environmental science, surface composition and topography control surface reactivity, and consequently play a major role in determining metallurgical phenomena and pollution by heavy metals and organics. An understanding of interaction mechanisms of different chemical species at the mineral surface in an aqueous media is very important in natural environment and metallurgical processing. X-ray photoelectron spectroscopy (XPS) has been used as an ex-situ analytical technique, but the material to be analyzed can be any size from $100\;{\mu}m$ up to about 1 cm. It can also measure mixed solids powders, but it is impossible to ascertain the original source of resulting x-ray signals where they were emitted from, since it radiates and scans the macro sample surface area. The study demonstrated the ability of TOF-SIMS to detect individual organic species on the surfaces of mineral particles from plant samples and showed that the TOF-SIMS techniques provides an excellent tool for establishing the surface compositions of mineral grains and relative concentrations of chemicals on mineral species.

• Journal of the Mineralogical Society of Korea
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• v.5 no.1
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• pp.32-41
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• 1992

An XRD quantitative analytical method using calculated XRD patterns was discussed in this study, Deep-seabed sediments commonly contain smectite, illite, chlorite, and kaolinite, and XRD pattern of each clay mineral of appropriate chemical composition was simulated by using an XRD pattern calculation method. Theoretical peak intensities of specific reflections of four clay minerals (the 001 reflections of smectite and illite, the 004 reflection of chlorite, and the 002 reflection of kaolinite) were measured from calculated patterns, and MIF(mineral intensity factor)value of each phase was determined from the intensities of calculated patterns. The peak intensities obtaine from experimental XRD patterns of sediments were corrected using the MIF values so that the calibrated intensity values for the specimens are linearly proportional to the weight fraction of each phase, which is normalized to 100 wt%. The MIF method can provide accurate quantitaive results without the necessity of correcting the factors by the mass absorption coefficient of each phase. This method excludes the necessity of standard specimens having compositions that are similar to those of clay minerals in the sediment samples. Therefore, quantitaive analysis using XRD calculation method can be utilized for the specimens, for which the standard specimens are very difficult or impossible to obtain. this quantitative method can provide rapid, routine analysis results for a large number of samples which occur in similar geological environments.

• Journal of Conservation Science
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• v.26 no.2
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• pp.109-120
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• 2010

Four gilded bronze objects and a gilded silver object were examined for elemental diffusion between the gilding layer and the mating matrix. The gilded bronzes consist of three objects from three different historical periods, the Korean Three Kingdoms period, the Koryo and the Choseon periods and one from an unknown period. The gilded silver was from the Koryo period. The amalgam process seems to have been the major technique employed for all of them in gilding. The occurrence of substantial diffusion was observed in all but the anonymous object, particularly in the Choseon artifact where evidence was found that the diffusion phenomenon was intentionally utilized in gilding. The gold content in the gilded bronzes decreases gradually from surface to interior while the copper content increases to the interior, making it difficult to locate the boundary between the gilding layer and the matrix. This gradual change in composition must have resulted from elemental diffusion at elevated temperatures. The oxygen content negligible in the gilding layer precludes the possibility of corrosion being responsible for the varying composition. It is observed that non-uniform diffusion caused variation of colors in the surface of gilded bronzes. The change of colors induced by diffusion, which is always accompanied by the unique surface morphology and chemical compositions, is distinguished from the color change by corrosion. In the gilded silver object, diffusion of mercury was observed along with that of gold and silver.

• Economic and Environmental Geology
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• v.29 no.4
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• pp.411-419
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• 1996

The Janggun magnetite deposits occur as the lens-shaped magnesian skarn, magnetite and base-metal sulfide orebodies developed in the Cambrian Janggun Limestone Formation. The K-Ar age of alteration sericite indicates that the mineralization took place during late Cretaceous age (107 to 70 Ma). The ore deposition is divided into two stages as a early skarn and late hydrothermal stage. Mineralogy of skara stage (107 Ma) consists of iron oxide, base-metal sulfides, Mg-Fe carbonates and some Mg- and Ca-skarn minerals, and those of the hydrothermal stage (70 Ma) is deposited base-metal sulfides, some Sb- and Sn-sulfosalts, and native bismuth. Based on mineral assemblages, chemical compositions and thermodynamic considerations, the formation temperature, $-logfs_2$, $-logfo_2$ and pH of ore fluids progressively decreased and/or increased with time from skarn stage (433 to $345^{\circ}C$, 8.8 to 9.9 atm, 29.4 to 31.6 atm, and 6.1 to 7.2) to hydrothermal stage (245 to $315^{\circ}C$, 11.2 to 12.3 atm, 33.6 to 35.4 atm, and 7.3 to 7.8). The ${\delta}^{34}S$ values of sulfides have a wide range between 3.2 to 11.6‰. The calculated ${\delta}^{34}S_{H_2S}$ values of ore fluids are relatively homo-geneous as 2.9 to 5.4‰ (skam stage) and 8.7 to 13.5‰ (hydrothermal stage), which are a deep-seated igneous source of sulfur indicates progressive increasing due to the mixing of oxidized sedimentary sulfur with increasing paragenetic time. The ${\delta}^{13}C$ values of carbonates in ores range from -4.6 to -2.5‰. Oxygen and hydrogen isotope data revealed that the ${\delta}^{38}O_{H_2O}$ and ${\delta}D$ values of ore fluids decreased gradually with time from 14.7 to 1.8‰ and -85 to -73‰ (skarn stage), and from 11.1 to -0.2‰ and -87 to -80‰ (hydrothermal stage), respectively. This indicates that magmatic water was dominant during the early skarn mineralization but was progressively replaced by meteoric water during the later hydrothermal replacement.

• Economic and Environmental Geology
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• v.36 no.6
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• pp.415-429
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• 2003

This study was objected to identify the difference of water quality and the characteristics of water contamination in adjacent bed-rock areas of Upper Hwajeonni and Guryongsan Formations in Miwon, Choongchungbuk-do, Korea. Water samples showed mainly (Ca, Mg)-$HCO_3$ type in Upper Hawjeonni Formation and (Ca, Mg)-$SO_4$ and (Ca, Mg)-$HCO_3$ types in Guryongsan Formation indicating the enrichment of $SO_4$ in major compositions. Groundwater quality could be divided into two groups based on the major weathering processes, implied by the ratio of bicarbonate to silica. Carbonate-silicate weathering predominates in Upper Hwajeonni Formation, and silicate weathering in Guryongsan Formation. Stream-water quality also appeared to be controlled by water-rock interaction. Cluster analysis identified three groups of groundwater and four groups of stream-water with distinctive geochemical characteristics. The results of factor analysis indicated that the levels of each chemical constituent in water samples derived from both natural weathering reactions and anthropogenic contamination sources. To delineate the pollution potential of water resources, Modified Pollution Index(M.P.I.) was developed. M.P.I. scores of water samples ranged from -0.08 to 0.18, with mostly positive along the rock quarry in Guryongsan Formation areas. M.P.I. scores appeared to be a useful predictor of metal contamination of water resources.

• Analytical Science and Technology
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• v.11 no.6
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• pp.485-494
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• 1998

Ternary and quaternary alloys composed of Mo-Ru-Rh-Pd were prepared and their crystal structure and quantitative chemical compositions were analysed by XRD, WDX, EDX and ICP/AES. The results of X-ray diffraction studies showed that the alloys were crystallized in hexagonal close packing, well known as ${\varepsilon}$-phase with $P6_3/mmc$ of space group. The optimum accelerating voltage for Zr~Cd(40~48) analyzed by EPMA using PET crystal was found to be 15 kV and the linear regression coefficient(R) of atomic number and X-ray intensity was approximately 0.998 without Tc standard specimen. The WDX results of alloys of Mo and Pd by linear regression equations were detected to be 0.1% lower compared to WDX analysis results using standard specimen, while Ru, Rh were detected 3% higher. These alloys were completely dissolved in mixed acid of 12.5 mL HCl and 1 mL $HNO_3$, at $220^{\circ}C$ for 22 hours using autoclave with PTFE vessel. There was no reprecipitating phenomnon when diluted 100 times with 1N-HCl. The results of ICP/AES analysis deviated less than 4% comparing with those of normal WDX analysis.

• Journal of Animal Science and Technology
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• v.50 no.2
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• pp.247-254
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• 2008

A total of 40 pigs were used to investigate the feeding effects of supplementary wild grape wine by-product on pork quality of American Berkshire breed in the swine farm of Hamyang area. Treatments were C that was basal diet, and T that was treated by dietary wild grape wine by-product(5%) were added in feed. About 70 kg pigs were bred a period of 88 days, and slaughtered. The pork quality characteristic were measured in pork loin. In chemical composition, moisture and crude fat were not significantly different between C and T, but T were lower(p<0.05) than C. There were no difference in crude protein and crude ash(p<0.05). pH and water holding capacity(WHC) were not significantly different between C and T, whereas the cholesterol and fat shear force of T were lower(p<0.05) than C. There were no different in the meat color, but the Hunter’s L* and W value of T were higher(p<0.05) than C. Oleic acid(C18:1), linoleic acid(C18:2, n-6), arachidonic acid(C20:4, n-6), Essential fatty acid(EFA), and EFA/unsaturated fatty acid were significantly(p<0.05) different between C and T, in the fatty acid compositions of loins. Also, the total amino acid composition of pork were not significantly different between C and T, but essential fatty acid of T was significantly higher(p<0.05) than that of C. This observation suggests that wild grape wine by-product supplements may have some beneficial effects on improving backfat color, shear force, cholesterol and essential fatty acid content of pork loin.

• The Korean Journal of Food And Nutrition
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• v.15 no.3
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• pp.209-214
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• 2002

This study was carried out to investigate the physicochemical properties of aloe added bagel. The result of sensory evaluation showed that addition of the aloe powder above 1% was not advisable because of its bitterness. freeze dried aloe powder(0, 1%, 0.5%, 1%) was added to bagel and chemical compositions of doughs were evaluated. The ash content of control was 0.444% and each of the samples(0.1%, 0.5%, 1%) was 0.472%, 0.553%, and 0.633% respectively. Although the ash content of dough increased gradually according to the addition of aloe powder, the volume of the bagel was not affected much. As the amount of the aloe powder was changed, the water absorption rate, the extensibility, and the viscosity of the dough were affected. The physical characteristics of dough were as follows: 1) The water absorption rate of the dough was gradually decreased from 65.3% at control, to 65.2% at 0.1%, 64.2% at 0.5%, 63.5% at 1% each by farinograph. 2) The extensibility of the dough was significantly declined at 1% by extensograph; from 20.7cm at control, to 20.3cm at 0.1%, 18.8cm at 0.5%, and 16.4cm at 1% each. 3) The top viscosity of the dough was sharply declined between 575 B.U at control and 515 B.U at 0.1%, afterwards, 480 B.U at 0.5%, 475 B.U at 1% each by viscograph. Considering the result of the test, aloe added bagel could promote physicochemical properties of dough as well as health effects.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.495-501
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• 2016

Mineral oil has been widely used as an insulating oil for electrical transformers for a long time, but the necessity of employing new insulation oil such as vegetable oil has been increased due to urgent needs for the biodegradability when it leaks and also for the thermal stability at a higher operation temperature. Although specific periods are required between the production and consumption, there are still short of the data to prove the insulation oils' storage stability depending upon various circumstances and their resources. Thus, this paper demonstrates the insulation oils' oxidation characteristics of both mineral and vegetable oils when each was exposed to different environments for 12 weeks. From this test, some properties including total acid number, water content and dielectric breakdown were changed under specific conditions and resources. Vegetable oils showed higher hydrophilicity and water saturation than those of mineral oils due to their molecular compositions. Under sunlight exposure condition, all insulation oils oxidized and changed their properties when exposing to the direct light, regardless of the resource used.