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RISS 인기검색어
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Cryoscopy of Amine-Polytungstates
변종홍,연손수,Pyun, Chong-Hong,Sohn, Youn-Soo Korean Chemical Society 1974 대한화학회지 Vol.18 No.2
Trioctylamine-and tricaprylylmethylammonium chloride-tungstate salts have been prepared by solvent extraction from the sodium tungstate solution of various acidities(pH = 2, 4, 6). The molecular weights of the amine-tungstate salts thus obtained could be cryoscopically measured in benzene by means of a home-built Wheatstone bridge utilizing thermistor with sensitivity of 1/$4000^{\circ}C$. The cryoscopic data along with the results of chemical analysis and infrared spectra of the salts indicate that the amine-tungstates prepared at pH = 2 and 4 are all metatungstate whereas the salt obtained at pH = 6 is an unknown form quite different from the expected paratungstate.R = 0.14. By hydrogen bonding a guanidyl nitrogen of a sulfaguanidine molecule is linked to the sulfonyl oxygens of the other molecules indirectly through two different water molecules. The role of water molecule is both a .nor and an acceptor in hydrogen-bonding formation and these hydrogen bonds are tetrahedrally o?ented. The hydrogen-bonding networks form infinite molecular layers parallel to (001) plane. 비수용성 긴고리 지방족 아민인$(n-C_8H_{17})_3N$과 $(n-C_8H_{17})_3NCH_3Cl$을 사용하여 산도가 틀린 텅그스텐산수용액(pH=2, 4, 6)으로 부터 용매추출법에 의하여 유기용매에 녹는 다중텅그스텐산아민염을 제조하는데 성공하였다. 제조된 텅그스텐산 아민염의 분자량을 벤젠용매에서 더미스트를 이용한 감도 1/$4000^{\circ}C$의 훼트스톤 브리지를 사용하여 측정할 수 있었다. 분자량 측정결과와 화학분석 및 적외선 스펙트럼으로 부터 pH=2, 4에서 생긴 아민염은 메타텅그스텐산염, pH=6에서 생긴 아민염은 파라텅그스텐산염이 아니고 미지의 새로운 다중텅고스텐산염임을 알 수 있었다.
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Derivative Thermometric Titrations Employing Operational Amplifier Instrumentation
채명준,변종홍,김상옥,Czae, Myung-Zoon,Pyun, Chong-Hong,Kim, Sang-Ok Korean Chemical Society 1970 대한화학회지 Vol.14 No.4
An improved derivative thermometric titration apparatus designed around operational amplifiers is described which is capable of monitoring the small temperature change and of computing the derivatives for accentuation of the titration end point that is difficult to locate by extrapolation methods. The instrument is constructed of four commercial operational amplifiers. A use of dummy cell provides the subtraction means for compensation of the initial temperature and random temperature fluctuations with a resultant gain in signal-to-noise ratio. The successive differentiation action of the computer has been nearly "perfect," so that the two breaks (blank or starting and end point of the titration curve can be located with the precision of 0.2% by observing two peak points on the second derivative curve. Arrangements useful in obtaining such a good derivative response that is exactly proportional to the input signal are discussed. Plots of the enthalphogram and its derivatives are presented, with the results of several titrations used to evaluate the performance of the apparatus.
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Phosphors for Plasma Display Panels
김창홍,배현숙,변종홍,홍광옌,Kim, Chang Hong,Bae, Hyun Sook,Pyun, Chong Hong,Hong, Guang Yan Korean Chemical Society 1998 대한화학회지 Vol.42 No.5
플라스마 표시판용으로 사용되거나 제안 또는 알려진 형광체들의 들뜸 및 발광 특성을 살펴 보았다. 각 형광체의 발광 효율이 임자 결정과 활성제의 종류에 따라 어떻게 달라지는지 알아 보았고 실용성 있는 형광체의 개발 방향을 생각하였다. Excitation and emission characteristics were reviewed for phosphors which were reported, applied, or suggested for the plasma display panel (PDP). Correlation of luminescence characteristics to the host crystal structure and the activator of the phosphor was explained. Improvements of the PDP phosphor for the practicality were considered.
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