• Korean journal of food and cookery science
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• v.16 no.5
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• pp.425-430
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• 2000

This study was carried out to estimate mineral contents of some underground vegetables including potatoes, sweet-potatoes, carrots, radishes, onions, and garlics produced in Korea using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). According to the measurements, the contents of Na, Mg, Al, K, Ca, Mn, Fe, Zn, and P in Korean underground vegetables were variable depending upon producing areas and individual plants. Compared with other underground vegetables, the contents of Na in carrots and lotus roots were quite high. The contents of Cd, Ag Co. and Sr appeared to be below hazard levels. It is expected that this study can be used to calculate the mineral intake from underground vegetables.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.152-152
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• 1999

1Gb급 이상 기억소자의 캐패시터 재료로 주목받고 있는 (Ba,Sr)TiO3 [BST] 박막의 전극재료로는 Pt, Ru, Ir과 같은 금속전극과 RuO2, IrO2와 산화물 전도체가 유망한 것으로 알려져 있다. 그런데, DRAM의 집적도가 증가하게 되면, BST같은 고유전율 박막을 유전재료로 사용한다 하더라도, 3차원적인 구조가 불가피하게 때문에 기존의 sputtering 방법으로는 우수한 단차피복성을 얻기 힘들므로, MOCVD법이 필수적이다. 본 연구에서는 기존에 연구되었던 Pt에 비해 식각특성이 우수하고, 비교적 낮은 비저항을 갖는 Ru 박막증착에 대한 연구를 행하였다. 본 연구에서는 수직형의 반응기와 저항 가열 방식의 susceptor로 구성된 저압 유기금속 화학증착기를 사용하여 최대 6inch 직경을 갖는 기판 위에 Ru박막을 증착하였다. Precursor로는 기존에 연구된 적이 없는 bis-(ethyo-$\pi$-cyclopentadienyl)Ru (Ru(C5H4C2H5)2, [Ru(EtCp)2])를 사용하였으며, bubbler의 온도는 85$^{\circ}C$로 하였다. Si, SiO2/Si를 사용하였으며, 증착온도 25$0^{\circ}C$~40$0^{\circ}C$, 증착압력 3Torr의 조건에서 Ru 박막을 증착하였다. Presursor를 운반하는 수송기체로는 Ar을 사용하였으며, carbon과 같은 불순물의 제거를 위해 O2를 첨가하였다. 증착된 박막은 XRD, SEM, 4-point probe등을 통해 구조적, 전기적 특성을 평가하였으며, 열역학 계산을 위해서는 SOLGASMIX-PV프로그램을 사용하였다. Ru 박막의 증착에 있어서 산소의 첨가는 필수적이었으며, Ru 박막의 증착속도는 30$0^{\circ}C$~40$0^{\circ}C$의 온도 영역에서 200$\AA$/min으로 일정하였으며, 첨가된 산소의 양이 적을수록 더 치밀하고 평탄한 표면형상을 보였으며, 또한 더 낮은 전기 전도도를 보였다. 그리고 증착된 박막은 12~15$\mu$$\Omega$cm 정도의 낮은 비저항 값을 나타냈으며 이것은 기존의 sputtering 법에 의해 증착된 Ru 박막의 비저항 값들과 비교될만하다. 한편, 높은 온도, 높은 산소분압 조건에서 RuO2의 형성을 관찰하였으며, 이것은 열역학적인 계산을 통해서 잘 설명할 수 있었다.

• Korean Journal of Materials Research
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• v.11 no.5
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• pp.367-371
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• 2001

In this paper, theS $r_2$(T $a_{1-x}$ , N $b_{x}$)$_2$ $O_{7}$(STNO) films among ferroelectric materials having a low dielectric constant for metal-ferroelectric-semiconductor field effect transistor(MFS-FET) were discussed. The STNO thin films were deposited on p-type Si(100) at room temperature by co-sputtering with S $r_2$N $b_2$ $O_{7(SNO)}$ ceramic target and T $a_2$ $O_{5}$ ceramic target. The composition of STNO thin films was varied by adjusting the power ratios of SNO target and T $a_2$ $O_{5}$ target. The STNO films were annealed at 8$50^{\circ}C$, 90$0^{\circ}C$ and 9$50^{\circ}C$ temperature in oxygen ambient for 1 hour. The value of x has significantly influenced the structure and electrical properties of the STNO films. In the case of x= 0.4, the crystallinity of the STNO films annealed at 9$50^{\circ}C$ was observed well and the memory windows of the Pt/STNO/Si structure were 0.5-8.3 V at applied voltage of 3-9 V and leakage current density was 7.9$\times$10$_{08}$A/$\textrm{cm}^2$ at applied voltage of -5V.of -5V.V.V.

• Economic and Environmental Geology
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• v.20 no.2
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• pp.85-95
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• 1987

The host rocks of titaniferous magnetite deposits in Gonamsan are alkaline gabbros, which are typical of undersaturated alkaline rocks in terms of the lack of normative quartz. According to field occurrences and petrographic features, these alkaline gabbros are divided into 3 rock types: coarse-grained and pegmatitic rock, medium-grained rock with equigranular texture, and layered cumulate rock. All these rocks mainly contain clinopyroxene(salite), plagioclase(An 43-66), pargasite, and ilmenite. The accessory minerals are apatite, sphene, quartz, and sometimes titaniferous magnetite. Pargasite, sphene, and quartz are considered to be secondary minerals formed by the reaction among clinopyroxene, plagioclase and Fe-Ti oxide at deuteric stage. Fe-Ti oxides generally occur as ilmenite in the alkaline rocks, and titaniferous magnetite in the ore deposits. Layered cumulate rocks are characterized by a recurrence of discontinuous thin mesolayer of clinopyroxene-pargasite within leucolayer mainly composed of plagioclase. Clinopyroxene is cumulus mineral whereas plagioclase, ilmenite and apatite occur as intercumulus minerals. According to the variation diagrams of oxide and trace element contents against the differentiation index, incompatible elements, such as Na, Ba and Sr, show positive correlations whereas compatible elements, such as Mg and Cr, show negative correlations. However some compatible elements, such as Co, Ni and V show irregular variations, reflecting relative cumulate status of cumulus and intercumulus minerals. On the de la Roche multicationic diagram, these alkaline gabbros are distributed along the differentiation curve of undersaturated alkaline series from alkaline basaltic composition through basanitic composition to tephritic composition. Layered cumulate rocks, which are distributed between basanitic composition and tephritic composition, reflect their cumulate character, slightly scattering away from the curve. The medium-grained rock shows higher contents in Ba, Sr and light rare earch elements than the coarse-grained and pegmatitic rock. The former shows two times higher contents of total rare earth elements than the latter, $while(La/Lu)_{cn}$ ratios maintain fairly constant values of 5.08~5.06 in these two rocks. This means that coarse-grained and pegmatitic rock, as compared with the medium-grained rock, was formed by the earlier differentiated magma but rare-earth element distribution pattern remained almost parallel during differentiation. From the data the above mentioned, these alkaline gabbros are considered to be comagmatic and to be formed by intrusions of differentiated magmas in its reservoir.

• Membrane Journal
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• v.18 no.3
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• pp.241-249
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• 2008

This study is to concentrate vanadium in Jeju groundwater using reverse osmosis processes, and to utilize the concentrate for vanadium water. Groundwater samples were taken from Wahyul, Ayum, and Seogwipo groundwater wells with different in vanadium content each other. Their vanadiuln concentrations were 31.8, 44.5, and 53.0 ppb, respectively. The rejection coefficients of every component in groundwater were increased with the increase of TMP At the TMP of $8 kg_f/cm^2$, the rejection coefficients of vanadium, sodium, potassium, aluminium, iron, and barium were $97.4%{\sim}99.0%,\;97.7%{\sim}97.8%,\;98.0%{\sim}98.3%,\;94.8%{\sim}97.5%,\;88.0%{\sim}96.4.0%$, and $97.9{\sim}98.0%$, respectively. And those of magnesium, calcium, chromium, mauganese, and strontium in three groundwater were more than 99.0% at the same TMP. It was possible that vanadium contents of Wahyul, Ayum and Seogwipo groundwater were concentrated into 58.6, 118.9, and 165.1 ppb, respectively, by 6 stages treatment at the recovery ratio of 15%. And these concentrated water (vanadium water) did not exceed the permissible drinking water standards.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.7
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• pp.473-478
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• 2001

Ferroelectric P $b_{0.99}$［(Z $r_{0}$ 6S $n_{0.4}$)/0.9/ $Ti_{0.1}$］0.98/N $b_{0.02}$ $O_3$(PNZST) thin films were deposited by a RF magnetron sputtering on L $a_{0.5}$S $r_{0.5}$Co $O_3$(LSCO)/Pt/Ti/ $SiO_2$/Si substrate using a PNZST target with excess PbO of 10 mole%. The crystallinity and electrical properties of the thin films annealed at various temperature and time were investigated. The thin films deposited at the substrate temperature of 500 $^{\circ}C$ and the power of 80 W were crystallized to a perovskite phase after rapid thermal annealing(RTA). The thin films annealed at 650 $^{\circ}C$ for 10 seconds in air exhibited the good crystal structures. The remanent polarization and coercive field of the PNZST capacitor were about 20 $\mu$C/$\textrm{cm}^2$ and 50 kV/cm, respectively. The reduction of the polarization after 2.2$\times$10$^{9}$ switching cycles was less than 10 %..10 %......

• Microbiology and Biotechnology Letters
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• v.25 no.2
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• pp.166-172
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• 1997

Aspergillus niger was selected as a strain producing the potent raw starch hydorlyzing enzyme. These experiments were conducted to investigate the conditions of the glucoa- mylase production, the purification of the enzyme, some characteristics of the purified enzyme and hydrolysis rate on various raw starches such as com, rice, potato, glutinous rice, sweet potato, wheat and barley. The optimum cultural temperature and time for the enzyme production on wheat bran medium were $30^{\circ}C$ and 96hrs, respectively. The respective addition of yeast extract and nutrient broth on wheat bran medium increased slightly the enzyme production. The enzyme was purified by ammonium sulfate fractionation and DEAE-cellulose column chromatography. The specific activity of the purified enzyme was 30.7u/mg-protein and the yield of enzyme activity was 25.8%. The purified enzyme showed a single band on polyacrylamide disc gel electrophoresis and its molecular weight was estimated to be 56,000 by SDS-polyacrylamide disc gel electrophoresis. The isoelectric point for the purified enzyme was pH3.7. The optimum temperature and pH were $65^{\circ}C$ and pH 4.0, respectively. The purified enzyme was stable in the pH range of pH 3.0-9.5 and below $45^{\circ}C$, and its thermal stability was slightly increased by the addition of $Ca^{2+}$. The purified enzyme was activated by $Co^{2+},\;Sr^{2+},\;Mn^{2+},\;Fe^{2+},\;Cu^{2+}$. Raw rice starch, raw corn starch, raw glutinous rice starch, raw sweet potato starch, raw wheat starch and raw barley starch showed more than 90% hydrolysis rate in 48hrs incubation. Even raw potato starch, most difficult to be hydrolyzed, showed 80% hydrolysis rate. The purified enzyme was identified as glucoamylase.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.865-875
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• 2016

In this study, mass concentrations and chemical compositions of $PM_{2.5}$, including water-soluble ions and elements were determined at the 1,100 m-highland of Mt. Hallasan in Jeju Island across four seasons from August 2013 to August 2014. The average mass concentration of $PM_{2.5}$ was $12.5{\pm}8.41{\mu}g/m^3$ with 45.8% of the contribution from eight water-soluble ionic species. Three ionic species ($SO{_4}^{2-}$, $NH{_4}^+$, and $NO{_3}^-$) comprised 96.2% of the total concentration of ions contained in $PM_{2.5}$ and were the dominant ions, accounting for 43.5% of the $PM_{2.5}$ mass at Mt. Hallasan. On the basis of the mass concentration level, seasonal variation, enrichment factor, and relationship among elements, we can presume that Mg, K, Ca, Mn, Fe, Co, Sr, Ba, Nd, and Dy originated mainly from crust or soil and that V, Cr, Ni, Cu, Zn, As, Cd, and Pb were significantly enriched in $PM_{2.5}$ owing to the effects of the anthropogenic emissions. These results and the local distribution of emission sources and topographic characteristics near this sampling site suggest that the compositions of $PM_{2.5}$ collected at the 1100 m-highland of Mt. Hallasan were largely influenced by inflow from outside of Jeju Island.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.70.1-70.1
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• 2012

In-situ X-ray photoelectron spectroscopy (XPS) and infrared (IR) spectroscopy studies of SOFC cathode materials will be discussed in this presentation. The mixed conducting perovskites (ABO3) containing rare and alkaline earth metals on the A-site and a transition metal on the B-site are commonly used as cathodes for solid oxide fuel cells (SOFC). However, the details of the oxygen reduction reaction are still not clearly understood. The information about the type of adsorbed oxygen species and their concentration is important for a mechanistic understanding of the oxygen incorporation into these cathode materials. XPS has been widely used for the analysis of adsorbed species and surface structure. However, the conventional XPS experiments have the severe drawback to operate at room temperature and with the sample under ultrahigh vacuum (UHV) conditions, which is far from the relevant conditions of SOFC operation. The disadvantages of conventional XPS can be overcome to a large extent with a "high pressure" XPS setup installed at the BESSY II synchrotron. It allows sample depth profiling over 2 nm without sputtering by variation of the excitation energy, and most importantly measurements under a residual gas pressure in the mbar range. It is also well known that the catalytic activity for the oxygen reduction is very sensitive to their electrical conductivity and oxygen nonstoichiometry. Although the electrical conductivity of perovskite oxides has been intensively studied as a function of temperature or oxygen partial pressure (Po2), in-situ measurements of the conductivity of these materials in contact with the electrolyte as a SOFC configuration have little been reported. In order to measure the in-plane conductivity of an electrode film on the electrolyte, a substrate with high resistance is required for excluding the leakage current of the substrate. It is also hardly possible to measure the conductivity of cracked thin film by electrical methods. In this study, we report the electrical conductivity of perovskite $La_{0.6}Sr_{0.4}CoO_{3-{\delta}}$ (LSC) thin films on yttria-stabilized zirconia (YSZ) electrolyte quantitatively obtained by in-situ IR spectroscopy. This method enables a reliable measurement of the electronic conductivity of the electrodes as part of the SOFC configuration regardless of leakage current to the substrate and cracks in the film.

• Journal of Microbiology and Biotechnology
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• v.24 no.1
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• pp.19-25
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• 2014

An extracellular agarase was purified from Bacillus sp. BI-3, a thermophilic agar-degrading bacterium isolated from a hot spring in Indonesia. The purified agarase revealed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular mass of 58 kDa. The optimum pH and temperature of the agarase were 6.4 and $70^{\circ}C$, respectively. The activity of the agarase was stable at high temperatures, and more than 50% activity was retained at $80^{\circ}C$ for 15 min. Furthermore, the enzyme was stable in the pH range of 5.8-8.0, and more than 60% of the residual activity was retained. Significant activation of the agarase was observed in the presence of $K^+$, $Na^+$, $Ca^{2+}$, $Mg^{2+}$, and $Sr^{2+}$; on the other hand, $Ba^{2+}$, $Zn^{2+}$, $Cu^{2+}$, $Mn^{2+}$, $Co^{2+}$, $Fe^{2+}$, and EDTA inhibited or inactivated the enzyme activity. The components of the hydrolytic product analyzed by thin-layer chromatography showed that the agarase mainly produced neoagarobiose. This study is the first to present evidence of agarolytic activity in aerobic thermophilic bacteria.