• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.332-334
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• 2000

The purpose of this study is to research and develop conducting polymer(CP) composite electrode for supercapacitor. Supercapacitor cell of CP composite electrode with 1M LiClO$_4$/ PC bring out good capacitor performance below 4V. The radius of semicircle of CP composite cell with PAn composite electrode adding 30wt% acetylene black was absolutely small. The total resistance of supercapacitor cell mainly depended on internal resistance of the electrode. The discharge capacitance of supercapacitor cell with PAn composite electrode adding 30wt% acetylene black in 1st and 50th cycles was 27F/g and 31F/g at current density of 1mA/$\textrm{cm}^2$. Supercapacitor cell with PAn composite electrode adding 30wt% acetylene black performed a good cycliability.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.370-373
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• 1999

The purpose of this study is to research and develop PAn composite electrode for EDLC. EDLC cell of PAn composite electrode with 1M LiClO$_4$/PC brings out good capacitor performance below 4.0V. The radius of semicircle of PAn composite electrode adding 15wt% SP270 was absolutely small. The total resistance of EDLC cell mainly depended on internal resistance of the electrode. The discharge capacitance of PAn composite with 15wt% SP270 in 1st and 200th cycles was 42 and 42 F/g at current density of 1mA/cm$^2$. The capacitance of PAn composite with 15wt%. SP270 capacitor was larger than that of PAn capacitor without SP270. The coulombic efficiency of EDLC at discharge process of 1 and 200 cycles were 94 and 100% respectively. PAn composite EDLC with 15wt% SP270 content showed good capacitance and stability with cycling.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.487-490
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• 2000

The purpose of this study is to research and develop conducting polymer(CP) composite electrode for supercapacitor. Electrochemical capacitor(supercapacitor) cell of CP composite electrode with 1M LiClO$_4$PC bring out good capacitor performance below 4V. The radius of semicircle of CP composite cell with PAn composite electrode adding l5wt%SP270(PAnS15) and PT composite electrode adding 50wt%SP270 (PTS50) was absolutely small. The total resistance of supercapacitor cell mainly depended on internal resistance of the electrode. The discharge capacitance of supercapacitor cell with PTS50(+)/PAnS15(-) in 1st and 20th cycles was 38F/g and 28F/g at current density of 1mA/cm$^2$. Supercapacitor cell with PTS50(+)/PAnS15(-) showed good capacitance and stability with cycling.

• 한국재료학회지
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• 제15권1호
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• pp.47-53
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• 2005

The E.M.F. of the galvanic cell with fused salt was measured to determine the activities of zinc at 720-860 K over the entire composition range of liquid Zn-In and Zn-Sn alloys. The cell used was as follows: $$(-)W{\mid}Zn(pure){\mid}Zn^{2+}(KCl-LiCl){\mid}Zn(in\;Zn-In\;or\;Zn-Sn\;alloy){\mid}W(+)$$ The activities of zinc in the alloys showed positive deviation from Raoult's law over the entire composition range. The activity of cadmium and some thermodynamic functions such as Gibbs free energy, enthalpy and entropy were derived from the results by the thermodynamic relationship. The comparison of the results and the literature data was made. The liquid Zn-In and Zn-Sn alloys are found to be close tn the regular solution. The concentration fluctuations in long wavelength limit, $S_{cc}(o)$, in the liquid alloy were calculated from the experimental results.

• Food Science and Biotechnology
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• 제17권2호
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• pp.257-261
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• 2008

Previous studies have suggested a possible correlation between cell surface hydrophobicity (CSH) and stress tolerance in Bifidobacterium. In this study, the relationship was examined between CSH and environmental stress tolerance in Lactobacillus spp. By measuring the adhesion to hexadecane, 2 Lactobacillus fermentum strains- KLB 261 and KLB 231 were found to have high and low CSH, respectively. To measure their tolerance to various stresses, cells were subjected to salt (2 M NaCl), acid (pH 2), $H_2O_2$ (0.01 %, v/v), ethanol (20%, v/v), heat ($60^{\circ}C$), and cold ($-20^{\circ}C$). Compared with KLB 231, the hydrophobic KLB 261 was found to be much more resistant to the various stresses examined. After being subjected to different stresses for a period of time, KLB 261 and KLB 231 showed 50 and 0% survivability in 2 M NaCl, 108.2 and 0.6% in 0.01 %(v/v) $H_2O_2$, 40.2%(v/v), and 3.7% at $60^{\circ}C$ incubation, 4 and 0.6% at $-20^{\circ}C$, 12.9 and 0.1 % in pH 2, 33.8 and 0.2% in 20%(v/v) ethanol, respectively. Autoaggregation test and morphological observation were also conducted in an attempt to explain these differences. These results suggested that high CSH could strengthen the stress tolerance of lactobacilli.

• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2438-2442
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• 2014

A kinetic study is reported for $S_NAr$ reaction of 1-fluoro-2,4-dinitrobenzene (5a) and 1-chloro-2,4-dinitrobenzene (5b) with alkali-metal ethoxides (EtOM, M = Li, Na, K and 18-crown-6-ether complexed K) in anhydrous ethanol. The second-order rate constant increases in the order $k_{EtOLi}$ < $k_{EtO^-}$ < $k_{EtONa}$ < $k_{EtOK}$ < $k_{EtOK/18C6}$ for the reaction of 5a and $k_{EtOLi}$ < $k_{EtONa}$ < $k_{EtO^-$ < $k_{EtOK}$ < $k_{EtOK/18C6}$ for that of 5b. This indicates that $M^+$ ion behaves as a catalyst or an inhibitor depending on the size of $M^+$ ion and the nature of the leaving group ($F^-$ vs. $Cl^-$). Substrate 5a is more reactive than 5b, although the $F^-$ in 5a is ca. $10pK_a$ units more basic than the $Cl^-$ in 5b, indicating that the reaction proceeds through a Meisenheimer complex in which expulsion of the leaving group occurs after the rate-determining step (RDS). $M^+$ ion would catalyze the reaction by increasing either the nucleofugality of the leaving group through a four-membered cyclic transition state or the electrophilicity of the reaction center through a ${\pi}$-complex. However, the enhanced nucleofugality would be ineffective for the current reaction, since expulsion of the leaving group occurs after the RDS. Thus, it has been concluded that $M^+$ ion catalyzes the reaction by increasing the electrophilicity of the reaction center through a ${\pi}$-complex between $M^+$ ion and the ${\pi}$-electrons in the benzene ring.

• 분석과학
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• 제8권1호
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• pp.17-23
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• 1995

$5.0{\times}10^{-2}M$ $LiClO_4$ 용액 중에서 펄스차이 폴라그래피로 2-mercapto-1-methyl-imidazole(MMI)의 정량방법을 조사하였다. 분석의 최적 조건은 초기전위 -0.9 volt vs. Ag/AgCl, 펄스높이 80mV, 주사속도 2mV/sec, 중간 크기 수은방울이었다. 검정곡선은 $1.0{\times}10^{-7}M$에서 $8.0{\times}10^{-5}M$ 범위까지 좋은 직선성을 보여 주었으며, 검출한계는 $2.2{\times}10^{-9}M$이었다. 이 방법은 다른 첨가제의 방해 없이 항갑상선 치료제 중의 MMI 정량에 응용할 수 있었다.

• 대한화학회지
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• 제65권2호
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• pp.125-132
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• 2021

An electrochromic nickel oxide thin film was fabricated on a flexible PET/ITO substrate using a nanocrystallite- dispersed coating sol and bar coater. Nanocrystalline NiOx of 3-4 nm crystallite size was first synthesized by base precipitation and thermal conversion. This NiOx nanocrystallite powder was mechanically dispersed in an alcoholic solvent mixed with a silane binder to prepare a coating sol for thin film. This sol method is different from the normal sol-gel method in that it does not require the conversion of precursor by heat treatment. Therefore, this method provides a very facile method to prepare NiOx thin films on any kind of substrate and it can be easily applied to mass production. The electrochromic performance of this NiOx thin film on PET/ITO electrode with a thickness of about 400 nm was investigated in a nonaqueous LiClO4 electrolyte solution by cyclic voltammetric and repeated chronoamperometric measurements in conjunction with spectrophotometry. The visible light modulation of 44% and the colorization efficiency of 41 ㎠/C at 550 nm were obtained at the step potentials of -0.8/+1.2 V vs Ag and a duration of 30 s.

• 한국재료학회지
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• 제25권9호
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• pp.475-479
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• 2015

$YNbO_4:Yb^{3+}/Er^{3+}$ is synthesized using a solid-state reaction process with a LiCl flux. The effects of the Er/(Yb+Er) ratios ($R_{Er}$) on the up-conversion (UC) and down-conversion (DC) spectra are investigated. The XRD data confirm that the $Yb^{3+}$ and $Er^{3+}$ ions are fully substituted for the $Y^{3+}$ sites. The UC emission spectra activated by 980 nm consists of green and red emission bands, which originate from the $Er^{3+}$ ions through an energy transfer (ET) process from $Yb^{3+}$ to $Er^{3+}$. The UC emission intensity depends on the $R_{Er}$ value, and the findings demonstrate that $R_{Er}{\leq}0.14$ is suitable for an effective UC process. The DC emission spectra under 269 nm radiation of the synthesized powders exhibits not only a strong blue emission assigned to the $[NbO_4]^{3-}$ niobates, but also green peaks that originate from the $Er^{3+}$ ions through an ET process between $[NbO_4]^{3-}$ and $Er^{3+}$.

• 광물과 암석
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• 제35권3호
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• pp.283-298
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• 2022

본 연구에서는 경상북도 울진 왕피리에 소재한 보암 Li 광산의 조장석-스포듀민 페그마타이트와 그 주변에 형성된 외영운암(exogreisen)의 광물 지화학 조성을 EDS로 분석하고 그 의미를 고찰하였다. 보암 광산은 화성활동 단계와 영운암화 단계의 두 단계를 거쳐 형성되었다. 전자에서는 조립질 내지 중립질의 스포듀민, 조장석, 석영, K-장석으로 구성된 조장석-스포듀민 페그마타이트가 관입하였으며, 후자에서는 페그마타이트의 조장석화 및 영운암화 과정에서 세립의 조장석 및 이와 공생하는 백운모, 녹주석, 인회석, 컬럼바이트족 광물(CGM, columbite group mineral), 마이크롤라이트, 석석 등이 형성되며 화성활동 단계의 광물을 부분적으로 교대하였다. 이 과정에서 주변암인 장군석회암과 맥의 경계면에는 전기석, 석영, 백운모로 구성된 외영운암이 형성되었다. 광물 지구화학 분석 결과에 따르면 화성활동 단계 대비 영운암화 단계에서 녹주석과 백운모에 Cs 함량이 더 높고 CGM의 Ta/(Nb+Ta) 또한 더 높게 나타난다. 이 같은 사실은 영운암화에 관여한 용융체가 페그마타이트를 형성한 용융체에 비하여 더 많은 분화 과정을 거쳤음을 지시한다. 영운암화 단계에서 형성된 인회석의 조성은 Cl이 결핍되고 F가 부화되어 있어 보암 광산이 S형 화강암 기원의 Li-Cs-Ta(LCT) 페그마타이트에 해당하는 특성을 지닌다. 화성활동 단계에 형성된 중립질의 조장석은 평균 0.28 wt.%의 P₂O₅를 갖는데 비해 영운암화 단계에 형성된 세립질의 조장석은 EDS 검출한계 미만의 P₂O₅를 지닌다. 영운암화 단계에 형성되는 인회석과 마이크롤라이트는 화성활동 단계 대비 Ca가 부화되었음을 지시한다. 따라서, 조장석 내 P의 결핍은 용융체에 있던 P가 주변암으로부터 Ca가 공급됨에 따라 인회석의 형태로 소진되어 결핍된 결과로 해석할 수 있다. 외영운암의 전기석은 중심에서 외곽으로 갈수록 Ca를 비롯한 2가 양이온의 함량이 증가하고 그에 따라 Al의 함량이 감소하는 화학적 누대구조를 보인다. 이는 영운암화 단계에서 장군석회암으로부터 용융체에 Ca가 점차 공급되었다는 가설에 부합한다.