• Progress in Superconductivity and Cryogenics
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• v.20 no.4
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• pp.41-45
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• 2018

We have investigated the effect of $Y_2O_3$ nanoparticles on the pinning properties of $Y_2O_3$-doped $GdBa_2Cu_3O_{7-{\delta}}$ (GdBCO) films. Both undoped and $Y_2O_3$-doped GdBCO films were grown on $CeO_2$-buffered MgO (100) single crystal substrates by pulsed laser deposition (PLD) using KrF (${\lambda}=248nm$) laser. The $Y_2O_3$ doping contents were controlled up to ~ 2.5 area% by varying the internal angles of $Y_2O_3$ sectors put on the top surface of GdBCO target. Compared with the $Gd_2O_3$-doped GdBCO films previously reported by our group [1], the $Y_2O_3$-doped GdBCO films exhibited less severe critical temperature ($T_c$) drop and thus slightly enhanced critical current densities ($J_c$) and pinning force densities ($F_p$) at 65 K for the applied field parallel to the c-axis of the GdBCO matrix (B//c) with increasing the doping content. Below 40 K, the in-field $J_c$ and $F_p$ values of all $Y_2O_3$-doped GdBCO films exhibited higher than those of undoped GdBCO film, suggesting that $Y_2O_3$ inclusions might act as effective pinning centers.

• Journal of Plant Biotechnology
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• v.42 no.3
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• pp.239-244
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• 2015

Calanthe striata f. sieboldii Decne. ex Regel is a terrestrial orchid with beautiful flowers arranged in racemose inflorescences. This species is threatened due to over-collection and loss of suitable habitats. Asymbiotic germination is useful in the conservation efforts to re-establish plants in the wild, and for commercial propagation. In this study, we investigate the effects of sodium hypochlorite (NaOCl), three types of culture media (Phytomax Orchid Maintenance - POM, Seed Germination Maintenance - SGM, and Murashige and Skoog 1962 - MS), and plant growth regulators on embryo swelling, protocorm formation, and embryo diameter of C. striata f. sieboldii. Treatment with 1% NaOCl for 30 min greatly enhanced embryo swelling (28.3%), embryo diameter ($205.8{\mu}m$), and embryo protocorm formation (54.8%) compared to seeds without NaOCl treatment (embryo swelling 8.5%, embryo diameter $14.6{\mu}m$, and protocorm formation 13.4%) on POM medium. Protocorm formation on POM medium supplemented with 1.0 mg/L N6-benzyladenine (BA) (95.6%) was better than the control (54.5%). Additionally, the effects of activated charcoal (AC) and sucrose on seedling growth in in vitro culture were examined. The protocorm converted into healthy plants with well-developed shoot primordia on the POM medium with AC and sucrose. The most suitable conditions for seedling growth after 10 weeks of culture were the POM medium with AC or sucrose. These results show effective asymbiotic seed germination and in vitro seedling growth of C. striata f. sieboldii.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.1
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• pp.1-14
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• 2021

The Unsang gold deposit has been one of the three largest deposits (Daeyudong, Kwangyang) in Korea. The geology of this deposit consists of series of host rocks including Precambrian metasedimentary rock and Jurassic Porphyritic granite. The deposit consists of Au-bearing quartz veins which filled fractures along fault zones in Precambrian metasedimentary rock and Jurassic Porphyritic granite, which suggests that it is an orogenic-type deposit. Quartz veins are classified as 1) galena-quartz vein type, 2) pyrrhotite-quartz vein type, 3) pyrite-quartz vein type, 4) pegmatic quartz vein type, 5) muscovite-quartz vein type and 6) simple quartz vein type based on mineral assembles. The studied quartz vein is pyrite-quartz vein type which occurs as sericitization, chloritization and silicification. The white mica from stylolitic seams of laminated quartz vein occurs as fine or medium aggregate associated with white quartz, pyrite, chlorite, rutile, monazite, apatite, K-feldspar, zircon and calcite. The structural formular of white mica from laminated quartz vein is (K0.98-0.86Na0.02-0.00Ca0.01-0.00Ba0.01-0.00 Sr0.00)1.00-0.88(Al1.70-1.57Mg0.22-0.09Fe0.23-0.10Mn0.00Ti0.04-0.02Cr0.01-0.00V0.00Ni0.00)2.06-1.95 (Si3.38-3.17Al0.83-0.62)4.00O10(OH2.00-1.91F0.09-0.00)2.00. It indicated that white mica of laminated quartz vein has less K, Na and Ca, and more Si than theoretical dioctahedral micas. Compositional variations in white mica from laminated quartz vein are caused by phengitic or Tschermark substitution [(Al3+)VI+(Al3+)IV <-> (Fe2+ or Mg2+)VI+(Si4+)IV] and direct (Fe3+)VI <-> (Al3+)VI substitution. The structural formular of chlorite from laminated quartz vein is((Mg1.11-0.80Fe3.69-3.14Mn0.01-0.00Zn0.01-0.00K0.07-0.01Na0.01-0.00Ca0.04-0.01Al1.66-1.09)5.75-5.69 (Si3.49-2.96Al1.04-0.51)4.00O10 (OH)8. It indicated that chlorite of laminated quartz vein has more Si than theoretical chlorite. Compositional variations in chlorite from laminated quartz vein are caused by phengitic or Tschermark substitution (Al3+,VI+Al3+,IV <-> (Fe2+ or Mg2+)VI+(Si4+)IV) and octahedral Fe2+ <-> Mg2+ (Mn2+) substitution. Therefore, laminated quartz vein and alteration minerals of the Unsan Au deposit was formed during ductile shear stage of orogeny.

• Microbiology and Biotechnology Letters
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• v.1 no.2
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• pp.93-98
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• 1973

The acid protease was isolated from the culture broth of the Penicillum sp. grown in the wheat bran media. 'quot;The crude purification of this enzyme was carried out by extraction with distilled water and precipitated with saturated ammonium sulfate. " The activity of this enzyme was found to be very strong by Folin′s colorimetric method. The results were as follows. 1. The optimum pH of the enzyme activity was at 3.0 and its optimum temperature was 5$0^{\circ}C$. 2. Although the enzyme activity to hydrolyze casein was maximal at 5$0^{\circ}C$, its activity decreased rapidly by about 50％, treated at 5$0^{\circ}C$ for 30 min. When treated at 4$0^{\circ}C$ for 60 min, the enzyme activity decreased to 75％ of original value and did not decrease any more. 3. The enzyme was stable at pH 2.0 to 6.0. 4. This enzyme activity was not effected by metal ions; C $d^{＋＋}$, Z $n^{＋＋}$, $Co^{＋＋}$, H $g^{＋＋}$, M $n^{＋＋}$, P $b^{＋＋}$, $Mg^{＋＋}$, L $i^{＋}$, C $u^{＋＋}$, $Ba^{＋＋}$, A $g^{＋}$, $Al^{＋＋＋}$, $Ca^{＋＋}$, F $e^{＋＋}$, and F $e^{＋＋}$ 5. Also, it was not effected by treatemnt of EDTA.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1638-1643
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• 2018

Multi-layer ceramic capacitors as decoupling capacitor were fabricated by dielectric composition with a high dielectric constant. The fabricated decoupling capacitors were embedded in the PCB of the 10G RF transceiver module and evaluated for the characteristics of electrical noise by the level of AC input voltage. In order to further improve the electrical properties of the $BaTiO_3$ based composite, glass frit, MgO, $Y_2O_3$, $Mn_3O$, $V_2O_5$, $BaCO_3$, $SiO_2$, and $Al_2O_3$ were used as additives. The electrical properties of the composites were determined by various amounts of additives and optimum sintering temperature. As a result of the optimized composite, it was possible to obtain a density of $5.77g/cm^3$, a dielectric constant of 1994, and an insulation resistance of $2.91{\times}10^{12}{\Omega}$ at an additive content of 5wt% and a sintering temperature of $1250^{\circ}C$. After forming a $2.5{\mu}m$ green sheet using the doctor blade method, a total of 77 layers were laminated and sintered at $1180^{\circ}C$. A decoupling capacitor with a size of $0.6mm(W){\times}0.3mm(L){\times}0.3mm(T)$ (width, length and thickness, respectively) and a capacitance of 100 nF was embedded using a PCB process for the 10G RF Transceiver modules. In the range of AC input voltage 400mmV @ 500kHz to 2200mV @ 900kHz, the embedded 10G RF Transceiver modules evaluated that it has better electrical performance than the non-embedded modules.

• Analytical Science and Technology
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• v.26 no.4
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• pp.276-286
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• 2013

This study was performed to investigate the contents characteristics of hazardous oil wastes and wastes of liquid fuels from different industrial process. In order to establish a hazardous waste list, samples of various industrial discharge have been analyzed for 16 non-regulated inorganic hazardous substances (i.e., Cu, Pb, Cd, CN, Hg, As, T-Cr, $Cr^{6+}$, Sb, Ni, F, V, Ba, Zn, Be, Se). In more detail, hazardous waste samples including waste hydraulic oils, waste engine, gear and lubricating oils, waste insulating and heat transmission oils, bilge oils, oil/water separator contents processing were collected from 37 workplaces and analyzed. We observed that the most of the inorganic substances exceeded the proposed criteria in many samples. Especially the concentration of Sb in heat transmission oil, bilge oil and gear & lubricating oils were ranged from 6 to 419 mg/kg whereas the proposed criteria is 50 mg/kg. The assessment result of hazardous waste in Korea according to the EWC showed that the out of 24 processes, 16 belongs to absolute entry and 8 belongs to mirror entry. In conclusion, we expect the outcome of this study to align the classification system of hazardous waste management in South Korea with international legislations, and consequently contribute to reduce environmental pollution as well as health risks by toxic wastes.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.216-221
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• 2010

Employing statistical design of experiments, the difference in doping behaviors of rare-earth ions and their effects on the dielectric property and microstructure of $BaTiO_3$-MgO-$MnO_2$-($Ba_{0.4}Ca_{0.6}$) $SiO_3-Re_2O_3$ (Re = $Y_2O_3$, $Er_2O_3$) system were investigated. Through the statistical analysis we have found that the amount of $Re_2O_3$ are significantly affecting on the dielectric properties. The $Re_2O_3$ improved the dielectric constant, dielectric loss and R*C constant, so the appropriate contents of $Y_2O_3$ and $Er_2O_3$ were 0.8 ~ 1.2 mol% and 0.8 ~ 1.3 mol%, respectively. The MLCC(mutilayer chip capacitor) with $2.0{\times}1.2{\times}1.2mm$ size and 475 nF was also suited for X7R with the above composition. It showed that the dielectric constant and RC constant were 2,839 and 3,675 ${\Omega}F$, respectively in the sintering condition at $1250^{\circ}C$ in $Po_2$ $10^{-7}$ Mpa.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.5
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• pp.440-446
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• 2008

To manufacture the MLCC with X7R for high voltage stability, $BaTiO_3-MgO-MnO_2-Y_2O_3$ with $(Ba_{0.4}Ca_{0.6})SiO_3$ glass frit was formulated. Based on this composition, the addition of $Er_2O_3$ showed that TCC(Temperature Coefficient Capacitance) at $85^{\circ}C$ was improved from 5 % to ${\sim}0\;%$, but the dielectric constant and IR (Insulation Resistance) were decreased. The glass frit improved the dielectric constant and IR, so the appropriate contents of $Er_2O_3$ and glass frit were 0.6 mol% and 1 wt%, respectively. It showed that the dielectric constant and RC constant were 2,550 and 2,000 (${\Omega}F$), respectively in the sintering condition at $1250^{\circ}C$ in PO2 $10^{-7}$ Mpa. The MLCC with $3.2{\times}1.6$ (mm) size and $1\;{\mu}F$ was also suited for X7R with the above composition.

• Journal of the Speleological Society of Korea
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• v.33 no.34
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• pp.7-22
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• 1993

본 연구에서는 단양지역에 분포한 석회암동굴계의 수질에 대한 주요 원소와 미량 원소 그리고 오염실태를 살펴보았다. 풍화물에 존재하는 미량 원소가 기반암보다 수 배 내지 수 백배 이상 부하되어 있었다. TSD와 EC 등은 화강암의 지하수 보다 높은 경향이 있었고 pH는 중성 내지 알칼리성이었다. Ca와 Mg은 기반암에서 용탈되어 지하수로 용존된 것으로 50ppm이상을 함유하고 있다. Fe과 K은 다른 주요 원소보다 현저히 낮은 경향이 있었다. 주요 음이온인 F$^{-}$ , Cl$^{-}$ , NO$_3$$^{-}$ , SO$_4$$^{-}$ 등은 환경기준치 보다도 현저히 낮은 상태이며, 따라서 오염이 안된 상태로 볼 수 있다. 미량 원소중 Al, Sr, Ba등이 높은 반면에 Co, Mo, Sb, Cs, W, Pb, U, Mn 등은 매우 극소량으로 존재하는 것으로 나타났다. 연구지역 중 온달굴, 고수굴, 천동, 노동 등지는 오염이 거의 안된 상태로 매우 양호한 편이나 천동굴은 관광객으로 인하여 일부 원소가 오염되어 있는 실정이다.

• Journal of the Mineralogical Society of Korea
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• v.11 no.1
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• pp.20-31
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• 1998

Adsorption of metal elements onto illite and halloysite was investigated at $25^{\circ}C$ using pollutant water collected from the gold-bearing metal mine. Incipient solution of pH 3.19 was reacted with clay minerals as a function of time: 10 minute, 30 minute, 1 hour, 12 hour, 24 hour, 1 day, 2 day, 1 week, and 2 week. Twenty-seven cations and six anions from solutions were analyzed by AAs (atomic absorption spectrometer), ICP(induced-coupled plasma), and IC (ion chromatography). Speciation and saturation index of solutions were calculated by WATEQ4F and MINTEQA2 codes, indicating that most of metal ions exist as free ions and that there is little difference in chemical species and relative abundances between initial solution and reacted solutions. The adsorption results showed that the adsorption extent of elements varies depending on mineral types and reaction time. As for illite, adsorption after 1 hour-reaction occurs in the order of As>Pb>Ge>Li>Co, Pb, Cr, Ba>Cs for trace elements and Fe>K>Na>Mn>Al>Ca>Si for major elements, respectively. As for halloysite, adsorption after 1 hour-reaction occurs in the order of Cu>Pb>Li>Ge>Cr>Zn>As>Ba>Ti>Cd>Co for trace elements and Fe>K>Mn>Ca>Al>Na>Si for major elements, respectively. After 2 week-reaction, the adsorption occurs in the order of Cu>As>Zn>Li>Ge>Co>Ti>Ba>Ni>Pb>Cr>Cd>Se for trace elements and Fe>K>Mn>Al, Mg>Ca>Na, Si for major elements, respectively. No significant adsorption as well as selectivity was found for anions. Although halloysite has a 1:1 layer structure, its capacity of adsorption is greater than that of illite with 2:1 structure, probably due to its peculiar mineralogical characteristics. According to FTIR (Fourier transform infrared spectroscopy) results, there was no shift in the OH-stretching bond for illite, but the ν1 bond at 3695 cm-1 for halloysite was found to be stronger. In the viewpoint of adsorption, illite is characterized by an inner-sphere complex, whereas halloysite by an outer-sphere complex, respectively. Initial ion activity and dissociation constant of metal elements are regarded as the main factors that control the adsorption behaviors in a natural system containing multicomponents at the acidic condition.