• 자원환경지질
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• 제26권4호
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• pp.433-444
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• 1993

전남(全南) 보성(寶城)지역 보덕(寶德) 광산의 에렉트럼 (은(銀)함량=32~73 atom. %)-황화광물 광화작용(鑛化作用)은 선캠브리아기(紀) 편마암(片麻岩)내의 단층(斷層) 열극을 충진한 석영맥(石英脈)으로 산출된다. 석영맥은 광물조성이 단순한 괴상(塊狀)이며, 구조(構造)적으로 2회에 걸쳐 형성되었다. 열수변질대(熱水變質帶) 견운모(絹雲母)에 대한 K-Ar 연령은 $155.9{\pm}2.3$ Ma로서 광화작용(鑛化作用)이 후기 쥬라기(紀)에 일어났음을 지시한다. 유체포유물(流體包有物) 연구에 의하면, 광화작용(鑛化作用)은 다양한 $CO_2$ 함량 ($X_{CO_2}=0.0{\sim}0.7$)과 저염도(低鹽度) (0.0~7.4 wt. % NaCl 상당농도(相當濃度))를 갖는 $H_2O-CO_2$계(系) 유체(流體)로부터 $200^{\circ}{\sim}370^{\circ}C$의 온도(溫度)범위에서 진행되었다. 광화유체(鑛化流體)의 불혼화(不混和) ($CO_2$비등(沸騰)) 증거는 광화용(鑛化用)시의 압력(壓力)이 약 1 kbar에 이르렀음을 지시한다. 금(金)-은(銀) 침전(沈澱)은 base-metal계(系) 황화광물(黃化鑛物) 보다는 후기, 약 $250^{\circ}C$ 근처에서 진행되었고, 유체(流體) 불혼화(不混和)에 따라 황화광물(黃化鑛物) 침전(沈澱) 및 $H_2S$ 일탈이 야기되면서 주로 냉각(冷却) 및 유황분압(硫黃分壓)의 감소에 기인하였다. 광화유체(鑛化流體)의 유황동위원소(硫黃同位元素) 조성 (${\delta}^{34}S_{{\Sigma}S}=1.7{\sim}3.3$‰)은 유황(硫黃)의 화성(火成)기원을 나타낸다. 한편, 광화유체(鑛化流體)의 산소(酸素)-수소(水素) 동위원소(同位元素) 조성 (${\delta}^{18}O_{water}=4.8{\sim}7.2$‰ ; ${\delta}D_{water}=-73{\sim}-76$‰)은, 보덕(寶德)광산의 심부(深部) 중온형(中溫型) 함금(含金) 광화유체(鑛化流體)는 동위원소적(同位元素的)으로 진화된 $H_2O-rich$ 순환천수(循環天水)와 심부(深部) magma 기원의 $H_2O-CO_2$ 유체(流體)와의 혼합물(混合物)로부터 기원했음을 지시한다.

• Journal of Pharmaceutical Investigation
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• 제41권6호
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• pp.371-376
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• 2011

The objective of this work was to investigate the existence of new crystal forms of tulobuterol which is used to prevent morning asthma attacks by ${\beta}_2$ agonist and the transformation of crystal forms. Three crystal forms of tulobuterol have been isolated by recrystallization and Form 2 was transformed to Form 4 at 52% RH and 95% RH and these four crystal forms are characterized by differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD) and thermogravimetric analysis (TG). The DSC and PXRD patterns of four crystal forms of tulobuterol were different respectively. The dissolution patterns of these three crystal forms of tulobuterol were studied and they showed significant differences in the dissolution rate. After storage of 2 months at 0% RH (silica gel, $20^{\circ}C$), 52% RH (saturated solution of $Na_2Cr_2O_7{\cdot}2H_2O/20^{\circ}C$) and 95% RH (saturated solution of $Na_2HPO_4/20^{\circ}C$), Form 1 and Form 3 were not transformed. But Form 2 was transformed to Form 4 at 52% RH and 95% RH.

• 자원환경지질
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• 제30권1호
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• pp.35-49
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• 1997

The coal formation of the Deokpyeong area are interbedded along metapelites of the Ogcheon Supergroup, which are composed mainly of graphite, quartz, muscovite and associated with small amounts of biotite, chlorite, pyrite and barite. The ratios of $SiO_2/Al_2O_3$, $Al_2O_3/Na_2O$ and $K_2O/Na_2O$ of the coaly metapelite are variable and wide range from 1.80 to 10.21, from 27.8 to 388.8 and from 7.6 to 61.8, respectively. These coal formation were deposited in basin of marine environments, and the REE of these rocks are not influenced with metamorphism and hydrothermal alterations on the basis of $Al_2O_3$ versus La, La against Ce, the ratios of La/Ce (0.19 to 0.99) and Th/U (0.02 to 4.75). These rocks also show much variation in $La_N/Yb_N$ (1.19 to 22.89), Th/Yb (0.14 to 21.43) and La/Th (0.44 to 13.67), and their origin is explained by derivation from a mixture of sedimentary and igneous rocks. The wide range in trace and REE element characteristics as Co/Th (0.12 to 2.78), La/Sc (0.33 to 10.18), Sc/Th (0.57 to 5.73), V/Ni (8 to 2347), Cr/V (0.02 to 0.67) and Ni/Co (1.56 to 32.95) of these coaly metapelites argues for inefficient mixing of the various source lithologies during sedimentation. Deep to pale green barium-vanadium muscovites (vanadium-oellacherite) have been found in this coal formations. Modes of occurrence and grain size of muscovite are heterogeneous, but most of the barium and vanadium-bearing muscovites occur along the boundaries between graphite and quartz grains, ranging from 200 to $350{\mu}m$ in length and from 40 to $60{\mu}m$ in width. Results of X-ray diffraction data of the minerals characterized to be monoclinic system with $a=5.249{\AA}$, $b=8.939{\AA}$, $c=20.924{\AA}$ and ${\beta}=95.894^{\circ}$. Representative chemical formula of the muscovite was $(Na_{0.09}K_{1.44}Ba_{0.46})(Al_{2.75}Ti_{0.07}V_{0.56}Fe_{0.08}Mg_{0.50})(Si_{6.12}Al_{1.88})O_{22}$. The V possibly substitute octahedral Al, and the Ba is coupled substitution of $K^+Si^{4+}=Ba^{2+}Na^+Ca^{2+}$, which compositional ranges of V and Ba are from 0.42 to 0.69 and from 0.34 to 0.56 based on $O_{22}$, respectively. Formation mechanism of the barium-vanadium muscovites in the coaly metapelite is shown that the formed by high pressure and temperature from regional metamorphism origanated during diagenesis at the interface between a basinal brine and organic matter.

• 한국전기전자재료학회논문지
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• 제31권5호
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• pp.300-306
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• 2018

The rod-shaped $Ni_{0.5}Zn_{0.5}Fe_2O_4$ particles were synthesized via a topotactic reaction, in which goethite (${\alpha}-FeOOH$) particles are the main constituents. The phases, microstructures and magnetic properties of these particles were studied using XRD, FE-SEM and VSM. The precursor solution consisted of $NiSO_4{\cdot}xH_2O$, $ZnSO_4{\cdot}xH_2O$, goethite and D.I. water werereacted at four different temperatures (50, 70, 90, $100^{\circ}C$) to generate four differently precipitated particles respectively. During the co-precipitation reaction, the pH of the solution was maintained at 8.0 using NaOH. The particles co-precipitated and calcined at a temperature of $700^{\circ}C$, exhibited a rod-shape similar to its original goethite, which means that the shape of Ni-Zn ferrite particles can be topotactically controlled by the goethite. The particles synthesized at 70 and $90^{\circ}C$ have a saturation magnetization of 29 and 35 emu/g respectively; representing better values than the ones synthesized at the 50 and $100^{\circ}C$, in which some second phases such as $Fe_2O_3$ were observed.

• 한국결정성장학회지
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• 제3권1호
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• pp.31-36
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• 1993

FZ법을 이용하여 Tourmaline ($NaFe_3Al_6B_3Si_6O_{27}F_4$) 단결정을 성장하였다. 성장조건으로 회전수 상호 역방향으로 20~30rpm, 성장속도 2~5mm/hr로 조절하였다. 성분 원소 중 전이금속 원소가 존재하여 dopant는 첨가하지 않았다. 원료봉은 $1000~1100^{\circ}C$에서 소결하였고 이 온도보다 고온의 영역에서는 F등의 휘발원소의 휘발로 인해 원료봉을 제작하기가 어려웠다. 성장된 결정은 어두운 색을 띄고 있었고 길이 60~50mm, 직경 5~6mm였다. 결정의 원료에 대하여 XRD 분석을 통하여 Tourmaline 조성을 확인하였고 FTIR로 성분의 결합상을 보았다.

• 센서학회지
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• 제15권1호
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• pp.65-70
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• 2006

Characteristics of thin-film NTC thermal sensors fabricated by micromachining technology were studied as a function of the thickness of membrane. The overall-structure of thermal sensor has a form of Au/Ti/NTC/$SiO_{X}$/(100)Si. NTC film of $Mn_{1.5}CoNi_{0.5}O_{4}$ with 0.5 mm in thickness was deposited on $SiO_{X}$ layer (1.2 mm) by PLD (pulsed laser deposition) and annealed at 873-1073 K in air for 1 hour. Au(200 nm)/Ti(100 nm) electrode was coated on NTC film by dc sputtering. By the results of microstructure, X-ray and NTC analysis, post-annealed NTC films at 973 K for 1 hour showed the best characteristics as NTC thermal sensing film. In order to reduce the thermal mass and thermal time constant of sensor, the sensing element was built-up on a thin membrane with the thickness of 20-65 mm. Sensors with thin sensing membrane showed the good detecting characteristics.

• Bulletin of the Korean Chemical Society
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• 제20권5호
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• pp.535-538
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• 1999

Five coordinated water-soluble iridium(l) complex, IrH(CO)(TPPTS)3 (1) (TPPTS = P(m-C6H4SO3Na)3-xH2O) has been prepared from the reaction of IrCl3·3H2O with TPPTS and HCHO in H2O/EtOH solution. Complex 1 catalyzes the hydration of nitrites (RC ≡ N, R = CH3, CICH2, CH3(CH2)4, Ph) in aqueous solution to give the corresponding amides (RCONH2) at 100℃. The hydration of unsaturated nitrites (R'C ≡ N, R'=CH3CH=CH, CH3OCH=CH, trans-PhCH=CH, CH2=C(CH3)) takes place regioselectively on-C ≡ N group to give unsaturated amides (R'CONH2) leaving the olefinic group intact. The yields of the amides seem to be depending on the electrophilicity of the carbon of nitrile: The more the electron withdrawing ability of the substituents on nitrites, the more amides are obtained. The hydration of dinitriles (NC-R-CN, R=(CH2)4, (CH2)6) with complex 1 initially gives mono-hydration products (NC-R-CONH2) which are slowly hydrated further to give dihydration products (H2NCO-R-CONH2). The hydration of 1,4-dicyanobutane has been found to be somewhat faster than that of 1,6-dicyanohexane.

• Transactions on Electrical and Electronic Materials
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• 제10권4호
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• pp.121-124
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• 2009

In this study, in order to develop compositions of ceramics suitable for piezoelectric actuator and ultrasonic vibrator applications using low temperature sintering, multilayer, PMN-PNN-PZT ceramics were fabricated using $Li_2CO_3$ and $Na_2CO_3$ as sintering aids. Their structural, piezoelectric and dielectric characteristics were investigated according to the Zr/Ti ratio. As the Zr/Ti ratio increased, the electromechanical coupling factor $k_p$, and piezoelectric constant $d_{33}$ and the mechanical quality factor $Q_m$ all increased with Zr/Ti ratio and then decreased after the ratio exceeded 50/50. At the ratio of Zr/Ti =49/51 and sintering temperature of $900^{\circ}C$; the density, electromechanical coupling factor $k_p$, dielectric constant ${\varepsilon}_r$ piezoelectric $d_{33}$ constant and mechanical quality factor $Q_m$ all showed the optimum values of 7.900 $g/cm^3$, 0.576, 856, 312 pC/N, 1,326, respectively. These property values are very suitable for multilayer ceramics actuator applications.

• 콘크리트학회논문집
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• 제18권4호
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• pp.449-458
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• 2006

시멘트는 전 세계적으로 사회기반 시설구조물의 주 건설 재료로서 경제 발전의 원동력이 되어 왔다. 그러나 시멘트 산업은 에너지 다소비형이며 또한 $CO_2$를 배출로 인한 온난화 현상 및 환경문제가 심각하다. 따라서, 본 연구에서는 시멘트를 사용하지 않은 21세기형 chemically bonded concrete를 연구하기 위해, 국내 fly ash를 재활용하여, 화학적 반응에 의해 경화시켜 모르타르 공시체를 제조하고, 시멘트 대체 건설재료로써 강도 발현 특성 분석, X-ray 회절분석(XRD), SEM 촬영을 통해 알칼리 활성제의 종류, 재령, 양생온도와의 상호관계와 반응 생성물의 강도 발현 메커니즘을 구명하였다. 실험 결과 알카리 활성제로 NaOH와 물유리를 사용한 시험체가 강도가 가장 높았으며, 초기의 높은 양생 온도는 조기에 fly ash의 반응을 활성화시켜 높은 강도 발현에 유리한 것으로 나타났다. 또한 XRD와 SEM 분석을 통해 주요한 반응생성물은 $Na_6-(AlO_2)_6-(SiO_2)_{10}-12H_2O$ 형태의 zeolite이며 그 밖의 칼슘실리케이트와 유사한 수화생성물로 나타났다.

• 한국분말재료학회지
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• 제26권1호
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• pp.49-57
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• 2019

Layered $LiNi_{0.83}Co_{0.11}Mn_{0.06}O_2$ cathode materials single- and dual-doped by the rare-earth elements Ce and Nd are successfully fabricated by using a coprecipitation-assisted solid-phase method. For comparison purposes, non-doping pristine $LiNi_{0.83}Co_{0.11}Mn_{0.06}O_2$ cathode material is also prepared using the same method. The crystal structure, morphology, and electrochemical performances are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) mapping, and electrochemical techniques. The XRD data demonstrates that all prepared samples maintain a typical ${\alpha}-NaFeO_2$-layered structure with the R-3m space group, and that the doped samples with Ce and/or Nd have lower cation mixing than that of pristine samples without doping. The results of SEM and EDS show that doped elements are uniformly distributed in all samples. The electrochemical performances of all doped samples are better than those of pristine samples without doping. In addition, the Ce/Nd dual-doped cathode material shows the best cycling performance and the least capacity loss. At a 10 C-rate, the electrodes of Ce/Nd dual-doped cathode material exhibit good capacity retention of 72.7, 58.5, and 45.2% after 100, 200, and 300 cycles, respectively, compared to those of pristine samples without doping (24.4, 11.1, and 8.0%).