• Applied Microscopy
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• v.51
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• pp.1.1-1.2
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• 2021

We demonstrate a fabrication of an atomically controlled single-crystal heart-shaped nanostructure using a convergent electron beam in a scanning transmission electron microscope. The delicately controlled e-beam enable epitaxial crystallization of perovskite oxide LaAlO₃ grown out of the relative conductive interface (i.e. 2 dimensional electron gas) between amorphous LaAlO₃/crystalline SrTiO₃.

• Journal of the Korean Home Economics Association
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• v.41 no.8
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• pp.55-62
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• 2003

Natural dyes generally fan into two categories; organic dyes coming from animals and plants and inorganic dyes obtained from various minerals such as bengala, loess, ultramarine, prussian blue and etc. The main components of volcanic ash is clay mineral such as kaolinite, illite, quartz. Clay minerals Composing volcanic ash are kaolinite［$Al_4Si_4O_{10}{(OH)_{8}}$］, illite［$K_{X}Al_2(Si,\;Al)_4O_{10}{(OH)}_2$］, quartz［$SiO_2$］, homblende［$Na_{0-1}\;Ca_2{(Mg,\;Fe,\;Al)}_5{(Si,\;Al)}_{8}O_{22}{(OH)}_2$］and etc. And the redish color mainly comes from iron oxide. In this paper, two different classes of dyeing process were tested; dyeing with volcanic ash only and cationic agent pre-treatment followed by dyeing with volcanic ash. The compositions of the volcanic ash powder and the volcanic ash deposited on the cotton knitted fabrics identified by energy dispersive spectrometer and XRD analysis. The major chemical components of volcanic ash deposited on the cotton knitted fabrics were confirmed to be the saicon oxide, iron oxide, and aluminum oxide and etc. According to the analysis by XRD and EDS-SEM, kaolinite, illite and quartz were also identified.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.6
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• pp.496-501
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• 2007

In order to enhance sintering characteristics on the $ZnO-Pr_6O_{11}$ based multilayer chip varistors (MLVs), a response surface analysis using central composite design method were carried out. As a result, varistor voltage($V_{1mA}$), nonlinear coefficient ($\alpha$), leakage current ($I_L$) and capacitance (C) were considered to be mainly affected by sintered temperature and holding time. MLVs sintered at $1200^{\circ}C$ and above $1200^{\circ}C$ revealed poor electrical characteristics, possibly due to the reaction between electrode materials(Pd) and $ZnO-Pr_6O_{11}$ based ceramics. On the sintering temperature range $1150{\sim}1175^{\circ}C$, nonlinear coefficient ($\alpha$) and leakage current ($I_L$) were shown to be $60{\sim}69$ and below $0.3{\mu}A$, respectively. In particular, MLVs sintered at $1175^{\circ}C$, 1.5 hr and $2^{\circ}C/hr$ (cooling speed) showed stable ESD(Electrical Static Discharge) characteristics under the condition of 10 times at 8 Kv with deviation varistor voltage, and deviation nonlinear coefficient were 0.3% and 0.33% (at positive), 0.55% (at negative), respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.3597-3601
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• 2013

In this study, a wet cleaning process, P II, using aqua-regia and sulfuric acid mixture with oxidant agent ($K_2S_2O_8$, $P_2O_5$, $KMnO_4$, $H_2O_2$ etc) is proposed to remove the metastable phase of graphite such as graphene and DLC for high quality synthetic diamonds. The process employed the conventional acid cleaning process (P I) as well as P I+P II to remove the graphite related impurities from the 200um-diamond powders synthesized at 7GPa-$1500^{\circ}C$-5minutes. The degree of cleaning after P I and P I+P II has been observed by naked-eye, optical microscopy, micro-Raman spectroscopy, and TGA-DTA. After P I+P II, the color of diamond became more vividly yellow with enhanced saturation with naked eye and optical microscopy analysis. Moreover, the disappearance of diamond-like-carbon (DLC) peak ($1440cm^{-1}$) observed by Raman spectroscopy confirmed the decrease in amount of remaining impurities. TGA-DTA results showed that the graphite impurities first started to dissolve at $770.91^{\circ}C$ after PI process. However, the pyrolysis started at $892.18^{\circ}C$ after P I+P II process because of the dissolution of pure diamonds. This result proved the effective dissolution of the metastable phase of graphite. We expect that the proposed P II process may enhance the quality of diamonds through effective removal of surface impurities.

• Journal of the Korean Ceramic Society
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• v.28 no.6
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• pp.465-470
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• 1991

AlN powder was synthesized by carbothermal reduction and nitridation of aluminum hydroxides precipitated in 5∼11 pH range from Al2(SO4)3$.$18H2O aqueous solution. Nitridation reactivity of hydroxide, which depends on precipitation pH, reaction temperature and time, was examined by XRD analysis at 1200∼1350$^{\circ}C$ and compared with that of commercial ${\alpha}$-Al2O3. Hydroxides obtained at higher pH could be more easily nitridated and, considering DTA/TG and BET results, the reason seems to be specific surface area difference of reactants depending on the content of decomposed structural water and the transition rate from transition-Al2O3 to ${\alpha}$-Al2O3.

• Journal of the Korean Ceramic Society
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• v.15 no.4
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• pp.199-204
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• 1978

In the present investigation, refined alumina obtained from alunite locally available was used as a aluminous source to synthesize monocalcium aluminate $(CA)_3$ the major mineral constituent of alumina cement. The influence of $SiO_2$ and $Fe_2O_3$ contents on the formation of monocalcium aluminate was studied by X-ray diffraction analysis mainly. About 0.8-1.0 of $Al_2O_3/C_3O$ mol ratio and less than 4 percent of $SiO_2$ were desirable for the effective formation of CA. The small amount of alkali and sulphur contents contained in refined alumina from alunite as the impurities were affected to form $C_4A_3S$ and $C_3S_2$, disadvantageous compounds for the alumina cement, therefore the impurities should be restricted in minimum content as possible.

• Speech Sciences
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• v.10 no.3
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• pp.145-155
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• 2003

This study compared $F_{0}$ and the first three formants of eight Korean monophthongs produced by nine transgenders (male to female) to those of eighteen normal adults. Voice analysis was done by Praat (version 4.049). A one-way ANOVA with Tukey HSD post hoc tests were performed to determine statistical differences in $F_{0}$ and formant values obtained from transgenders, and normal male and female subjects. Results indicated that there was no significant difference in $F_{1}$ of /u/, /$\Lambda$/, and /o/, $F_{2}$ of /u/, /$\Lambda$/, and /i/ and $F_{3}$ of /u/ among the 3 groups (transgenders, normal males and normal females). However, in the comparison of transgenders vs. males, a significant difference was observed in $F_{0}$ of /o/, and $F_{2}$ of /i/, /a/, /e/, and /${\ae}$/ and $F_{3}$ of /e/. Furthermore, in the comparison of transgenders vs. females, a significant difference was also observed in $F_{0}$ of all vowels, $F_{1}$ of /i/, /$\alpha$/, /e/, /${\ae}$/, and /i/. $F_{2}$ of /i/, and /${\ae}$/, and $F_{3}$ of /i/, /$\alpha$/, /$\Lambda$/, /e/, /${\ae}$/, /i/, and /o/. Also, perceptual judgment of the transgenders' voice came out somewhat correlated strongly with their $F_{0}$ values but not much with the formant values. It was concluded that the transgenders' acoustic parameters are placed in between those of the normal males and females in. terms of fundamental and formant frequency analyses of vowels. Thus, it was assumed that those differences might stem from the transgenders' original big resonating cavities.

• Journal of the Korean Chemical Society
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• v.57 no.4
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• pp.447-454
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• 2013

In this research, two new complexes of N-(2-aminoethyl)-1,3-propanediamine (aepn), $[Cd(aepn)_2]I_2$ (1) and $[Cd(aepn)_2]Cl_2{\cdots}H_2O$ (2), were prepared and identified by elemental analysis, FT-IR, Raman spectroscopy and single-crystal X-ray diffraction. Geometry around the cadmium atom in two complexes by coordination of six nitrogen atoms of two aepn is distorted octahedral. If distortion in the mer-$[Cd(aepn)_2]^{2+}$ cation is disregarded, it has a $C_2$ axis and $C_2$ symmetry. The cyclic voltammetry experiments were carried out to study the complexation process. Two structural surveys on coordination modes and complexes of aepn are presented. A study was carried out using CSD data to estimate the averages of bond lengths for different types of the Cd-N bonds. It was found that the intermolecular $N-H{\cdots}I$, $C-H{\cdots}I$ hydrogen bonds in 1 and $N-H{\cdots}Cl$, $N-H{\cdots}O$, $C-H{\cdots}O$, $O-H{\cdots}Cl$ in 2 stabilized the crystal networks.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.113-119
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• 2005

The methods that are used for receiving data from attached devices under real-time preemptive multi-task operating system (OS) by general processors can be categorized as polling and interrupt driven. The technical approach to these methods may be different due to the application specific scheduling policy of the OS and the programming architecture of the flight software. It is one of the most important requirements on the development of the flight software to process the data received from satellite subsystems or components with the exact timeliness and accuracy. This paper presents the analysis of the I/O method of device related scheduling mechanism and the reliable data I/O methods between processor and devices.

• Journal of Communications and Networks
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• v.11 no.5
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• pp.509-517
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• 2009

This work proposes a new distributed and self-organized authentication scheme for mobile ad-hoc networks (MANETs). Apart from describing all its components, special emphasis is placed on proving that the proposal fulfils most requirements derived from the special characteristics of MANETs, including limited physical protection of broadcast medium, frequent route changes caused by mobility, and lack of structured hierarchy. Interesting conclusions are obtained from an analysis of simulation experiments in different scenarios.