• Korea Trade Review
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• v.47 no.4
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• pp.177-195
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• 2022

This study analyzed the volatility spillover effect between international non-ferrous metal futures markets using the BEKK-GARCH model. Statistical data are futures price data of copper (CU), aluminum (AL), nickel (NI), tin (SN) from Shanghai Futures Exchange (SHFE) and London Metal Exchange (LME) from April 1, 2015 to December 31, 2021. Combining the research results, first, in the case of copper, aluminum, and nickel, it was found that there was a two-way volatility spillover effect between the Shanghai and London markets, and the international influence of the London market was greater. Second, in the case of the tin, it was found that the Shanghai market has a volatility spillover effect on the London market from stage I, and it is strengthened in stage II. Third, in the case of nickel, it was found that there was a two-way volatility spillover effect in the first stage, but in the second stage, the London market had a unidirectional volatility spillover effect with respect to the Shanghai market. This study confirmed that China's influence in the international non-ferrous metal futures market is gradually increasing. In addition, it suggested that international investors can engage in arbitrage and hedging using China's non-ferrous metal futures market.

• Journal of the Korean Society for Heat Treatment
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• v.37 no.5
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• pp.215-220
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• 2024

Slip lines and dislocation structures developed by deformation at 77 K, 292 K and 500 K have been investigated by an optical microscope and a high-voltage electron microscope. Slip patterns after the deformation by 4-5% at 77 K and 500 K are compared. From the slip line geometry, operation of both primary and secondary {111} slips have been confirmed. However, the primary slip lines formed at 77 K appear coarser and more pronounced than those at 500 K. This indicates that a larger number of dislocations have moved on the same plane at 77 K. Another characteristic difference noted here is that the slip lines are straight and pass through the specimen from one end to the other at 77 K. On the contrary, slip lines are rather faint at 500 K. The typical change found at 77 K is the increase in the [$0{\bar{1}}1$] dipole dislocations and generation of the [$10{\bar{1}}$] screw dipoles upon increase in the strain from 1.2% to 5.2%. This is the indication that the straight dipole dislocations were formed by a pinning effect due to jogs generated by mutual cutting between primary and secondary dislocations. Extremely fine slip has been noted after deformation at 500 K indicating that the usual Frank-Read source is not operative at high temperatures due to the strong KW locking.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.24-24
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• 1998

반도체장비를 포함하는 초고진공장비의 園훌化가 급속히 그리고 절실히 요구되고 있는 것이 현실정이다. 當面해서 실현할 국산진공장비의 대상은 廣範圍하다. 즉, 각종 진공 pump ( (rotary, dry, diffusion, cryo, ion, turbo melecular pump), 진공 chamber, 진공 line, gate valve 를 위 시 한 진공 V머ve, flange, gasket, fl않d야lU, mainpulater 퉁 진공 部品이 다. 진공계 의 핵심 은 適切하고 優良한 진공재료의 선태파 사용이다. 진공장비는 사용자가 원하는 진공도를 원하 는 시간 동안 륨空度를 유지해 주어야 한다. 진공재료 선태의 기준사항은:(1) 기체의 透過성 (2) 薰했훌 (3) 혔體放出특성 - -outgassing과 degassing- (4) 機械的 량훌度 (5) 온도 의존성 (6) 化學톡성 (7) 加I성 및 鎔接 성 (8) 課電특성 (9) 磁氣특성 (10) 高速함子 및 放射線 특성 (11) 經濟성 및 調達생 둥이 다. 우량한 초고진공계재료는 풍부하게 개발되어 왔고, 또 新材料들이 개발되고 있다. 여기에서는 주로 초고진공 내지는 극고진공계의 構造材料, 機能材料, 部品材料 일반파 몇가지 신재료의 특 성에 관해서 記述한다. M Mild SteeHSAE, 1112, 1010, 1020, 1022, etc)., S Stainless SteeHAlSI, 304, 304L, 310, 316, 321, 347): 구조재료, chamber, fl하1ges A Aluminum과 Alloys (1060, 1100, 2014, 4032, 6(뻐1): 구조재료, chamber, flanges, gaskets A AI, Al 떠loy는 SS에 代替하는 역 할올 시 작하고 있다. C Copper, Copper Alloys(C11$\alpha$)0, C26800, C61400, Cl7200): 내장인자, gasket, cryopanel, tubing T Titanium, Ziriconium, Haf띠um 및 Alloys: 특히 Ti은 10n pump 용 getter material 이 외 에 U UHV,XHV용 chamber계로서 관심올 끌고 있다. N Nickel, Nickel Alloys (200, 204, 211, monel, nichrome): 부식 방지 , 전자장치 , 자기 장치 귀 금속(Ag, Au, Pt, Pd, Rh, Ir, Os, Ru): 보조부품, gasket, filament, coating, thermocouple, 접 합부위 T TiC, SiC, zrC, HfC, TaC 둥의 탄화물과, BN, TiN, AlN 동의 질화물, 붕화물이 둥장하고 었 다. 유리: Soda Lime, Borosilicate, Potash Soda Lead: View Port, Chamber envelope C Ceramics: AlZ03, BeO, MgO, zrOz, SiOz, MgOzSiOz, 3Alz032SiOz, Z$textsc{k}$hSiOz S상N4: e electrical, thermal insulators, crucibles, boats, single crystals, sepctr려 windows 저자는 최근 저자들이 발견한 Zr-Ti-Cu-Ni-Be amorphous alloys coated cham뾰r가 radiation p proof로 이용될 수 있는 사실을 점검하고 었다 .. Z.Y. Hua 들은 Cs3Sb를 새로운 photocathode 재료로 보고하고 있다.

• Economic and Environmental Geology
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• v.25 no.1
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• pp.27-39
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• 1992

Several pyrophyllite deposits occur around the Milyang area where Cretaceous andesitic rocks and spatially related granitic rocks are widely distributed. Pyrophyllite ores consist mainly of pyrophyllite, and quartz with small amount of sericite, pyrite, dumortierite, and diaspore. The andesitic rocks and spatially related granitic rocks in this area suggest that they could be formed from the same series of a calc-alkaline magma series. The contents of $SiO_2$, $Al_2O_3$, LOI(loss on ignition) are enriched, and $K_2O$, $Na_2O$, CaO, MgO, $Fe_2O_3$ are depleted in altered andesitic rocks and ores. Enrichment of As, Cr, Sr, V, Sb and depletion of Ba, Cs, Ni, Rb, U, Y, Co, Sc, Zn are characteristic during mineralization. The pyrophyllite ores can be discriminated from the altered-and unaltered wall-rocks by an increasing of $(La/Lu)_{cn}$ from 4.18~22.13 to 8.98~55.05. In R-mode cluster analysis, Yb-Lu-Y, La-Ce-Hf-Th-U-Zr, $TiO_2-V-Al_2O_3$, Sm-Eu, $CaO-Na_2O-MnO$, Cu-Zn-Ag, $K_2O-Rb$ are closely correlated. In the discriminant analysis of multi-element data, $P_2O_5$, As, Cr and $Fe_2O_3$, Sr are helpful to identify the ores from the unaltered-and altered wall-rocks. In the factor analysis, the factors of alteration of andesitic rocks and ore mineralization were extracted. In the change of ions per unit volume, $SiO_2$, $Al^{3+}$ and LOI are enriched and $Na^+$, $K^+$, $Ca^{2+}$, $Mg^{2+}$, $Mn^{2+}$ and $Fe^{3+}$ are depleted during the alteration processes. The Milyang and the Sungjin pyrophyllite deposits could be mineralized by hydrothermal alteration in a geochemical condition of low activity ratio of alkaline ions to hydrogen ion with reference to spatially related granitic rocks.

• Analytical Science and Technology
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• v.13 no.6
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• pp.766-774
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• 2000

The major and trace constituents of Mongolian chromite were analyzed by ICP-AES. The dissolution procedures, mixed acid ($HClO_4+H_3PO_4$) digestion and fusion with $Na_2O_2$ flux, have been studied to dissolve the chromite. The optimum dissolution method was found to be a fusion with $Na_2O_2$ flux. The effect of large amount of Na on major and trace constituents was examined when these elements were determined by ICP-AES. There was no effect on major elements at a concentration of Na 250 mg/L solution. The emission intensity of trace constituents containing Na 1,250 mg/L decreased to 1.0-5.2% according to elements and wavelengths. The result of this method was compared with that of neutron activation analysis (NAA) to confirm the accuracy of this procedure. The results between two methods were in a good agreement within less than 5% for $Al_2O_3$, $Cr_2O_3$, MgO and -20 to 8% for Co, Mn, V, Zn, respectively.

• Journal of Wetlands Research
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• v.23 no.3
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• pp.213-223
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• 2021

To understand the sedimentary environment of Scirpus planiculmis habitat (Myeongji and Eulsuk tidal flats) in the Nakdong Estuary, this study analyzed the statistical parameters (sorting, skewness, and kurtosis) of grain size data and the major (Al, Fe, Mn, Mg, Ca, Na, K, Ti, and P), minor (Li, Sc, V, Cr, Co, Ni, Cu, Zn, Sr, Zr, Cs, Pb, Th, and U), and rare earth elements (REEs) in sediment cores. For Myeongji, the sediment structure of the upper part of the cores was poorly sorted, more finely skewed, and more leptokurtic due to construction of the West gate. By contrast, the Eulsuk cores all differed due to the contrasting floodgate operation patterns of the West and East gates. The linear discriminate function (LDF) results corresponded to the statistical parameters for grain size. At the Eulsuk tidal flat (sites ES05 and ES11), elemental distributions were representative of Al-, Fe- and Ca-associated profiles, in which the elements are largely controlled by the accumulation of their host minerals (such as Na- and K-aluminosilicate and ferromagnesium silicate) and heavy detrital minerals at the sites. Detrital minerals including the aluminosilicates are major factors in the elemental compositions at ES05, diluting the REE contents. However, clay minerals and Fe-oxyhydroxides, as well as REE-enriched heavy minerals, appeared to be controlling factors of the elemental composition at ES11. Therefore, the mineral fractionation process is important in determining the elemental composition during sedimentation, which reflects the depositional condition of riverine-saline water mixing at both sites.

• Economic and Environmental Geology
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• v.56 no.6
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• pp.799-816
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• 2023

Mineralogical and geochemical studies of shales within the Lower Anambra Basin was conducted to unravel the depositional environment, provenance, maturity, paleo-weathering conditions, and tectonic settings. Mineralogical studies conducted using X-ray diffraction analysis revealed that the samples were composed of kaolinite, montmorillonite, chlorite, and illite. KaolinIite is the dominant mineral, constituting approximately 41.5% of the bulk composition, whereas the non-clay minerals are quartz, ilmenite, and sillimanite. Geochemical analysis showed a predominance of SiO₂, Al₂O₃, and Fe₂O₃ contents of the shale samples with mean values of 52.29%, 14.09%, and 6.15% for Imo Shale (IS); 52.31%, 16.70%, and 7.39% for Mamu Shale (MS); 43.21%, 21.33%, and 10.36% for Enugu Shale (ES); 53.35%, 15.64%, and 7.17% for Nkporo Shale (NS); and 51.24%, 17.25%, and 7.78% for Agwu Shale (AS). However, the shales were depleted in Na₂O, MgO, K₂O, MnO, TiO₂, CaO, and P₂O₅. The trace element ratios of Ni/Co and Cu/Zn of the shale suggest an oxic depositional environment. The average SiO₂ vs. Al₂O₃ ratio of the shales indicated textural maturity. Compared to the PAAS standard, the shales plot below the PAAS value of 0.85, suggesting a high degree of maturity and intensive chemical weathering, further confirmed on a CIA vs. PIA plot. On log (K₂O/Na₂O) against SiO₂ and tectonic setting discriminant function diagrams, the shales plot mostly in the field of passive continental margin tectonic setting. The discriminant function diagrams as well as Al₂O₃/TiO₂ ratio of the shales showed that they were derived from a mixed source (mafic and intermediate igneous rocks).

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.368-375
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• 2006

Single and complex metal oxide catalysts supported onto a commercial DT51D $TiO_2$ have been investigated for gas-phase TCE oxidation in a continuous flow type fixed-bed reaction system to develop a better design approach to catalysts for this reaction. Among the $TiO_2$-supported single metal oxides used, i.e., $CrO_x,\;FeO_x,\;MnO_x,\;LaO_x,\;CoO_x,\;NiO_x,\;CeO_x\;and\;CuO_x$, with the respective metal contents of 5 wt.%, the $CrO_x/TiO_2$ catalyst was shown to be most active for the oxidative TCE decomposition, depending significantly on amounts of $CrO_x\;on\;TiO_2$. The use of high $CrO_x$ loadings greater than 10 wt.% caused lower activity in the catalytic TCE oxidation, which is probably due to production of $Cr_2O_3$ crystallites on the surface of $TiO_2$. $CrO_x/TiO_2$-supported $CrO_x$-based bimetallic oxide catalysts were of particular interest in removal efficiency for this TCE oxidation reaction at reaction temperatures above $200^{\circ}C$, compared to that obtained with $CrO_x$-free complex metal oxides and a 10 wt.% $CrO_x/TiO_2$ catalyst. Catalytic activity of 5 wt.% $CrO_x-5$ wt.% $LaO_x$ in the removal reaction was similar to or slightly higher than that acquired for the $CrO_x$-only catalyst. Similar observation was revealed for 5 wt.% $CrO_x$-based bimetallic oxides consisting of either 5 wt.% $MnO_x,\;CoO_x,\;NiO_x\;or\;FeO_x$. These results represent that such $CrO_x$-based bimetallic systems for the catalytic TCE oxidation on significantly minimize the usage of $CrO_x$ that is well known to be one of very toxic heavy metals, and offer a very useful technique to design new type catalysts for reducing chlorinated volatile organic substances.

• Journal of Food Hygiene and Safety
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• v.36 no.3
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• pp.264-270
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• 2021

In this study we investigated the elution level of lead (Pb), cadmium (Cd), arsenic (As), zinc (Zn), nickel (Ni), antimony (Sb), germanium (Ge), aluminum (Al) and hexavalent chromium (Cr⁶⁺) from 69 home-cooking utensils into a food stimulants. The results of migration testing according to the Korea standards and specifications for utensils, containers and packages showed values the allowable migrantion limits. Al was detected in all 7 utensil materials with the average concentration ranging from 0.002-5.989 mg/L. According to the migration conditions for (180℃, 30 min), the average concentration of Al in paper was 7.2 times higher than 25℃, 10 min (P<0.05). The results of migration testing at 180℃, 30 min were also below the allowable migrantion limits. When comparing with the provisional tolerable weekly intake (PTWI) of Al, the estimated weekly intakes (EWI) accounted for 0.000-0.045% for Al.

• Economic and Environmental Geology
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• v.30 no.6
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• pp.553-566
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• 1997

Origin, behavior and enrichment of environmental toxic elements from the Deokpyeong area were investigated on the basis of major, trace and rare earth element geochemistry. Coaly metapelites of the Deokpyeong area are subdivided into grey phyllite, dark grey phyllite, coaly slate and black slate, which are interbedded along the Ogcheon Supergroup. The coaly slate had been mined for coal, but mining is closed. The coaly and black slates are lower contents of $SiO_2$ and $Al_2O_3$, and higher contents of LOI, CaO, $Na_2O$ and BaO as compared with the phyllitic rocks. Rare earth elements are highly enriched in the coaly and black slate. Average compositions (ppm) of minor and/or environmental toxic elements in the coaly and black slate are revealed as As=127, Ba=30,163, Cd=18, Cr=740, Cu=84, Mo=378, Pb=43, Sb=12, Se=44, U=144, V=8,147 and Zn=292, which are extremely high concentrations than those in the NASC compositions. Major elements (average enrichment index; 5.34) in the coaly metapelites are mostly depleted, excepting $P_2O_5$ and BaO, normalized by NASC. Rare earth elements (average enrichment index; 1.48) are enriched in the coaly slate. On the basis of NASC, minor and/or environmental toxic elements in the coaly metapelites were strongly enriched of all the elements with the exception of Co, Cs, Ni and Sr. Average enrichment index of trace elements in coaly metapelite is 31.51 (coaly slate; 51.94 and black slate; 15.46). Especially, enrichment index of potentially toxic elements (As, Ba, Cr, Cu, Mo, Ni, Sb, Se, U, V and Zn) of the rock is 46.10 (grey phyllite; 7.15, dark grey phyllite; 4.77, coaly slate; 88.96 and black slate; 22.11). These coal formations were deposited in basin of boundary between terrestrial and marine environments deduced to carbon, sulfur (C/S=2.2 to 275.7), trace and rare earth elements characteristics. Irregular behavior and dispersion between major, minor and rare earth elements of those metapelites indicates a variable source materials, incomplete mixing of differential source and/or reequilibrium of diagenesis and metamorphism.