• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.174-177
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• 1991

Fluorine-doped $SnO_2\;(SnO_2:F)$ films were prepared in ordinary atmosphere on borosilicate glass substrates using pyrosol deposition method starting from the solutions composed of $SnCl_4-5H_2O-NH_4F-CH_3OH-H_2O-HCl$ in an attempt to develop transparent conductors for use in amorphous silicon (a-Si) solar cello. The deposition rate of films increased with the increase in the content of $H_2O$, whereas it decreased with increasing the content of $CH_3OH$. When air was used as the carrier gas, the lowest electrical resistivity was obtained from a solution having $CH_3OH/H_2O$ mol ratio of about $2{\sim}3$ in the solution. The use of $N_2$ of the same flow rate as the carrier gab resulted always in the high resistive films, but the resistivity of the films decreased continuously with the increase in the content of $H_2O$. The surface morphology and preferred orientation of films were also affected by the solvent composition and the content of HCl in the solution. The room-temperature resistance of the films were fairly stable after heat-treatments up to $600^{\circ}C$.

• Analytical Science and Technology
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• v.12 no.6
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• pp.528-533
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• 1999

The total iodine is determined in serum, fresh milk and feed additive by ICP-MS. The preparation involves only a 25-fold dilution with a diluent by direct nebulization in the plasma. The diluent composition is $NH_4OH$(0.5% v/v)+$CH_3OH$(5% v/v) and the abundance of iodine is measured at m/z=127. The calibration curve was linear over the ranges $0-100{\mu}g/L$ with $R^2=0.99$ for iodine. The detection limit of this method is $0.084{\mu}g/L$ for iodine. The relative error range of milk powder SRM in optimum condition is 2.30%-4.73%. The concentration ranges of iodine in the serum, fresh milk, feed additive were $12.4-40.2{\mu}g/L$, < 0.01-3.11 mg/L, < $10^{-7}-2.60g/kg$ respectively.

• Journal of Surface Science and Engineering
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• v.28 no.1
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• pp.55-63
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• 1995

Alkaline solutions such as $NH_4$OH, choline and TMAH (($CH_3$)$_4$NOH) have been introduced in semiconductor wet processing of silicon wafers to control ionic and particulate impurities following etching in acidic solutions. These chemicals usually mixed with hydrogen peroxide and/or surfactants to control the etch rate of silicon. The highest etch rate was observed in $NH_4$OH solutions at a pH in alkaline solutions. It indicates that the etch rate depends on the content of $OH^{-}$ as well as cations of alkaline solutions. STM/AFM techniques were used to characterize the effect of alkaline solutions on silicon surface roughness. In SC1 (mixture of $NH_4$OH : $H_2$$O_2$ : $H_2$O) solutions, the reduction of the ammonium hydroxide proportion from 1 to 0.1 decreased the surface roughness ($R_{rms}$) from 6.4 to $0.8\AA$. The addition of $H_2$$O_2$ and surfactants to choline and TMAH reduced the values of $R_{p-v}$ and $R_{rms}$ significantly. $H_2$$_O2$ and surfactants added in alkaline solutions passivate bare silicon surfaces by the oxidation and adsorption, respectively. The passivation of surfaces in alkaline solutions resulted in lower etch rate of silicon thereby provided smoother surfaces.s.ces.s.

• Proceedings of the Ginseng society Conference
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• 1993.09a
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• pp.206-214
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• 1993

Ginseng saponins have been known as main active principles and analyzed as the index components in ginseng and its products for quality control. But it is generally difficult to analyze the saponins in crude drug preparations. Saponins, Prosapogenins and sapogenins of crude drug preparation were identified by TLC and determined quantitatively by HPLC. $Prosapogemins-Rg_3\;-Rg_2\;and\;{\Delta}^{20}-prosapogenin$ were extracted with ethyl acetate from $50\%$ acetic acid hydrolyzates of saponin fractions and identified by TLC with lower phase of $CHCl_3/MeOH/H_2$ O\65:35:10. v/v)on silica gel plate, and quantified by HPLC on $Lichrosorb-NH_2$ column with $CH_3CN/H_2O(90:10,\;v/v).$ Sapogenins. panaxadiol and panaxatriol. were extracted with ethyl ether from $7\%-sulfuric$ acid hydrolyzates of saponin fractions and identified by TLC with chloroform/acetone(1 : 1 v/v) on silica gel plate. and quantified by HPLC on u - Bondapak $C^{18}$ column with $CH_3CN/MeOH/CHCl_3(83:10:7.\;v/v).$ These analyses of prosapogenins and sapogenins are more useful for quality control than those of saponins in crude drug preparations such as So - Shi - Ho - Tang(소시호탕), Sa - Kun - Ja - Tang(사군자탕), Yook - Kun - Ja - Tang(육군자탕), and In - Sam -Tang(인삼탕)

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.141-141
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• 2018

Copper is one of the most abundant metals on earth. Its oxide (CuO) is an intrinsically p-type metal-oxide semiconductor with a bandgap ($E_g$) of 1.2-2.0 eV 1. Copper oxide nanomaterials are considered as promising materials for a wide range of applications e.g., lithium ion batteries, dye-sensitized solar cells, photocatalytic hydrogen production, photodetectors, and biogas sensors 2-7. Recently, high-density and uniform CuO nanostructures have been grown on Cu foils in alkaline solutions 3. In 2011, T. Soejima et al. proposed a facile process for the oxidation synthesis of CuO nanobelt arrays using $NH_3-H_2O_2$ aqueous solution 8. In 2017, G. Kaur et al. synthesized CuO nanostructures by treating Cu foils in $NH_4OH$ at room temperature for different treatment times 9. The surface treatment of Cu in alkaline aqueous solutions is a potential method for the mass fabrication of CuO nanostructures with high uniformity and density. It is interesting to compare the gas sensing properties among CuO nanomaterials synthesized by this approach and by others. Nevertheless, none of above studies investigated the gas sensing properties of as-synthesized CuO nanomaterials. In this study, CuO nanowalls versus nanoparticles were synthesized via the oxidation process of Cu foil in NH4OH solution at $50-70^{\circ}C$. The gas sensing properties of the as-prepared CuO nanoplates were examined with $C_2H_5OH$, $CH_3COCH_3$, and $NH_3$ at $200-360^{\circ}C$.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.6
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• pp.818-829
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• 2013

The collection of rainwater samples was made at Jeju area during 2009~2010, and the major ionic species were analyzed. In the comparison of ion balance, conductivity, and acid fraction for the validation of analytical data, the correlation coefficients showed a good linear relationship within the range of 0.966~0.990. The volume-weighted mean pH and electric conductivity were 4.9 and $17.8{\mu}S/cm$, respectively, at the Jeju area. The volume-weighted mean concentrations of ionic species in rainwater were in the order of $Cl^-$ > $Na^+$ > $nss-SO_4{^{2-}}$ > $NH_4{^+}$ > $NO_3{^-}$ > $Mg^{2+}$ > $H^+$ > $nss-Ca^{2+}$ > $HCOO^-$ > $K^+$ > $PO_4{^{3-}}$ > $CH_3COO^-$ > $NO_2{^-}$ > $F^-$ > $HCO_3{^-}$ > $CH_3SO_3{^-}$. The ionic strength of rainwater was $0.26{\pm}0.21$ mM during the study period. The composition ratios of ionic species were such as 50.1% for the marine sources ($Na^+$, $Mg^{2+}$, $Cl^-$), 30.9% for the anthropogenic sources ($NH_4{^+}$, $nss-SO_4{^{2-}}$, $NO_3{^-}$), and 4.7% for the soil source ($nss-Ca^{2+}$), and 3.1% for organic acids ($HCOO^-$, $CH_3COO^-$). From the seasonal comparison, the concentrations of $NO_3{^-}$, $nss-Ca^{2+}$, and $nss-SO_4{^{2-}}$ increased in winter and spring seasons, indicating a reasonable possibility of long range transport from Asia continent. Especially, the acidifying contributions by major inorganic acids ($nss-SO_4{^{2-}}$ and $NO_3{^-}$) and organic acids ($HCOO^-$ and $CH_3COO^-$) were 87.6% and 12.4%, respectively. In comparison by sectional inflow pathway of air mass during the rainy sampling days, the concentrations of $nss-SO_4{^{2-}}$ and $NO_3{^-}$ were relatively high when the air mass was moved from the China continent into Jeju area.

• Korean Journal of Crystallography
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• v.8 no.1
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• pp.59-63
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• 1997

A method for the calculation of the idealized hydrogen positions in the following seven different kinds of compounds has been shown: (1) tertiary C-H, (2) secondary C-H, (3) $CH_3$ group with tetrahedral angles, (4) aromatic C-H or amide N-H, (5) O-H group with X-O-H angle tetrahedral, (6) terminal $X=CH_2$ or $X=NH_2^+$ with the hydrogen atoms in a plane and (7) acetylenic C-H with X-C-H linear.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.29-29
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• 2009

현재 고집적 비휘발성 메모리 소자로는 MRAM (Magnetic Random Access Memory)과 PRAM (Phase Magnetic Random Access Memory)이 활발하게 미국과 일본, 한국 등에서 다양한 연구가 진행되어 오고 있다. 이 중에서 MRAM은 DRAM과 비슷한 10 ns의 빠른 읽기/쓰기 속도와 비휘발성 특성을 가지고 있으며, 전하를 저장할 커패시터가 필요 없고, 두 개의 자성충에 약 10 mA 정도의 전류를 가하면 그때 발생하는 약 10 Oe의 자장을 개개의 비트를 write하고, read 시에는 각 비트의 자기저항을 측정함으로써 데이터를 저장하고 읽을 있으므로, 고집적화가 가능성하다 [1]. 현재 우수한 박막 재료가 개발 되었으나, 고집적 MRAM 소자의 양산에는 해결 하여야 하는 문제점이 있다. 특히 다층 박막으로 구성되어 있으므로 식각 공정의 개발이 필수적이다. 지금까지 MRAM 재료의 식각은 주로 Ion milling, ICP, ECR등의 플라즈마 장치를 되었고, 식각 가스로는 할로겐 기체와 금속카보닐 형성을 위한 Co/$NH_3$와 $Ch_3OH$ 기체가 이용되고 있다. 그러나 할로겐 계열의 기체를 사용할 경우, 식각 부산물들의 높은 끓는점 때문에 식각 부산물이 박막의 표면에서 열적 탈착에 의하여 제거되지 않기 때문에 높은 에너지를 가지는 이온의 도움에 의한 식각이 필요하다. 또한 Cl 계열의 기체를 사용할 경우, 식각 공정 후, 시료가 대기에 노출되면 대기 중의 수분과 식각 부산물이 결합하여 부식 현상이 발생하게 된다. 그러므로 이를 방지하기 위한 추가 공정이 요구된다. 최근에는 부식 현상이 없고, MTJ 상부에 사용되는 Ta 또는 Ti Hard mask와의 높은 선택비를 가지는 $CH_3OH$ 또는 CO/$NH_3$가 사용되고 있다. 하부 박막에 따른 식각 특성에 연구와 다층의 박막의 식각 공정에 발생에 관한 발표는 거의 없다. MRAM을 양산에 적용하기 위하여서는 Main etch 공정에서 빠른 식각 공정이 필요하고, Over etch 공정에서 하부박막에 대한 높은 선택비가 요구된다. 그러므로 본 논문에서는 식각 변수에 따른 플라즈마 측정과 표면 반응을 비교하여 각 공정의 식각 메커니즘을 규명하고, Main Etch 공정에서는 $Cl_2$/Ar 또는 $BCl_3$/Ar 가스를 이용하여 식각 실험을 수행하고, Over etch 공정에는 낮은 Ta 박막 식각 속도를 가지는 $Ch_4/O_2$/Ar 또는 $Ch_3OH$/Ar 가스를 이용하고자 한다. 플라즈마 내의 식각종과 Ta 박막과의 반응을 XPS와 AES를 이용하여 분석하고, 식각 공정 변수에 따른 식각 속도, 식각 선택비와 식각 프로파일 변화를 SEM을 이용하여 관찰한다.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.4
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• pp.240-245
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• 2015

This study aimed to provide the basic data to establish measures for the management of the public toilets and reduction of the offensive odor through the air dilution olfactory method and instrumental analysis about offensive odor dilution rate of public toilets, focusing on the Dong-gu, Daejeon Metropolitan City, Korea. The offensive odor intensities ranged from 10 degree to 669 degrees in the urinal toilets and from 31 to 464 in closet bowl toilets. Meanwhile, toilets that had offensive odor of more than 2.5, of which a civil complaint can be filed, were researched 6 (33%). Offensive odor intensities were different according to the closet bowl toilets of the flush, fermented and conventional methods and the year of their installation, but not according to the area of the toilets. As a result of the instrumental analysis targeting 6 public toilets to identify the offensive odor substance, the maximal concentration of $NH_3$ was 2.04 ppm and the average concentration was 0.67 ppm, but $H_2S$, $CH_3SH$ and $(CH_3)_3N$ were not detected. In the fermented and conventional public toilets were not soaps, air fresheners and wastebaskets. Just 50% of the flush toilets had toilet tissue.

• Bulletin of the Korean Chemical Society
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• v.26 no.6
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• pp.935-938
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• 2005

Nucleophilic addition reactions of benzylamines (BA; $XC_6H_4CH_2NH_2$) to $\alpha-cyano-\beta$-phenylacrylamides (CPA; $YC_6H_4CH=C(CN)CONH_2$) have been investigated in acetonitrile at 25.0 ${^{\circ}C}$. The rate is first order with respect to BA and CPA and no base catalysis is observed. The addition of BA to CPA occurs in a single step in which the addition of BA to $C_{\beta}$ of CPA and proton transfer from BA to $C_{\alpha}$ of CPA take place concurrently with a four-membered cyclic transition state structure. The magnitude of the Hammett ($\rho_X$) and Bronsted ($\beta_X$) coefficients are rather small suggesting an early tansition state (TS). The sign and magnitude of the crossinteraction constant, $\rho_XY$ (= −D0.26), is comparable to those found in the normal bond formation processes in the $S_N2$ and addition reactions. The normal kinetic isotope effect ($k_H/k_D\;{\gt}$ 1.0) and relatively low ${\Delta}H^{\neq}$ and large negative ${\Delta}S^{\neq}$ values are also consistent with the mechanism proposed.