• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.210-213
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• 2002

The blue phosphor, $BaMgAl_{10}O_{17}$:$Eu^{2+}$, showing a blue emission band at about 450 nm were prepared by solid state reaction of BaC $O_3$, A $l_2$ $O_3$, MgO and E $u_2$ $O_3$ with Al $F_3$ as a flux. The thermal quenching of BaMgAl $O_{17}$:E $u^{2+}$ phosphor significantly reduces the intensity of the blue emission. It is reduced by an amount of 50% after heating at around 800$^{\circ}C$ for 1 hr. The red emission in the 580∼720 nm region of $^{5}$ $D_{0}$\longrightarro $w^{7}$ $F_1$ and $^{5}$ $D_{0}$\longrightarro $w^{7}$ $F_2$ transition of $Eu^{3+}$ is produced from the phosphor heated above 1,100$^{\circ}C$. The EPR spectrum also reveals that some part of E $u^{2+}$ ions are oxidized to trivalent ions above 1,100$^{\circ}C$ at around 90 and 140mT. This oxidation evidence is also detected from XANES absorption spectra for $L_{III}$ shell of Eu ions: an absorption peak is at 6,977eV of E $u^{2+}$ and 6,984eV of $Eu^{3+}$. The combined X-ray and neutron data suggests that the new phase of EuMgA $l_{11}$ $O_{19}$ magnetoplumbite structure may be formed by heat treatment.eat treatment.tment.eat treatment.tment.t.

• Speech Sciences
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• v.5 no.2
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• pp.17-26
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• 1999

It has been claimed that Korean mid-vocalic voiceless unaspirated lax stops are phonetically realized with voicing throughout the oral closure phase. Acoustic measurements were undertaken to examine the claim with four Korean native speakers using /$V_1CV_2$/ words where the vowel ($V_1\;=\;V_2$) was /i, a, u/ and the C was voiceless unaspirated lax stops /p, t, k/. Findings: (1) During mid-vocalic stops /k/ and /p/ the vowel /u/ was accompanied generally by a significant increase in voice cessation time as percentage of the oral closure interval (PCT) than the vowel /a/, regardless of subjects, whereas in mid-vocalic alveolar stop /t/ the effects of vowels on PCT were subject-dependent, (2) The effects of vowels on PCT were significantly greater in mid-vocalic /k/ than /p/, regardless of subjects, (3) The mean PCT, averaged across six tokens, ranged from 17% to100%, giving overall mean 61% in which the standard deviation was ${\pm}30$, and (4) Overall % of the total of mid-vocalic unaspirated lax stops were produced with a substantial period of devocing and voicing lag. Considering these results, it is difficult to agree with the existing claims that Korean voiceless unaspirated lax stops are phonetically realized with voicing throughout the oral closure phase. Other phonetic variables, including the durations of pre/post-stop vowels, voice onset time, voice cessation time, and the duration of oral closure, were measured.

• Journal of Microbiology and Biotechnology
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• v.21 no.10
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• pp.1012-1020
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• 2011

A gene coding for an endoglucanase (EglA), of the glycosyl hydrolase family 12 and derived from Aspergillus niger VTCC-F021, was cloned and sequenced. The cDNA sequence, 717 bp, and its putative endoglucanase, a 238 aa protein with a predicted molecular mass of 26 kDa and a pI of 4.35, exhibited 98.3-98.7% and 98.3-98.6% identities, respectively, with cDNA sequences and their corresponding endoglucanases from Aspergillus niger strains from the GenBank. The cDNA was overexpressed in Pichia pastoris GS115 under the control of an AOX1 promoter with a level of 1.59 U/ml culture supernatant, after 72 h of growth in a YP medium induced with 1% (v/v) of methanol. The molecular mass of the purified EglA, determined by SDS-PAGE, was 33 kDa, with a specific activity of 100.16 and 19.91 U/mg toward 1% (w/v) of ${\beta}$-glucan and CMC, respectively. Optimal enzymatic activity was noted at a temperature of $55^{\circ}C$ and a pH of 5. The recombinant EglA (rEglA) was stable over a temperature range of $30-37^{\circ}C$ and at pH range of 3.5-4.5. Metal ions, detergents, and solvents tested indicated a slightly inhibitory effect on rEglA activity. Kinetic constants ($K_m$, $V_{max}$, $k_{cat}$, and $k_{cat}/K_m$) determined for rEglA with ${\beta}$-glucan as a substrate were 4.04 mg/ml, 102.04 U/mg, 2,040.82 $min^{-1}$, and 505.05, whereas they were 10.17 mg/ml, 28.99 U/mg, 571.71 $min^{-1}$, and 57.01 with CMC as a substrate, respectively. The results thus indicate that the rEglA obtained in this study is highly specific toward ${\beta}$-glucan. The biochemical properties of rEglA make it highly valuable for downstream biotechnological applications, including potential use as a feed enzyme.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.585-586
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• 2008

In this paper, a novel beta-multiplier reference current source circuit for the 800mV power-supply voltage is presented. In order to cope with the narrow input common-mode range of the OpAmp in the reference circuit, shunt resistive voltage divider branches were deployed. High gain OpAmp was designed to compensate intrinsic low output resistance of the MOS transistors. The proposed reference circuit was designed in a standard 0.18um CMOS process with nominal Vth of 420mV and -450mV for nMOS and pMOS transistor respectively. The total power consumption including OpAmp is less than 50uW.

• Journal of Korean Society of Transportation
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• v.17 no.2
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• pp.21-27
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• 1999

The objective of this study is to clarify the relationship between accident rate and V/C for freeway facility. The relationship can be used as a basic reference to predict and prevent traffic accident. The traffic volume and the number of accidents from 1992 to 1997 on Shingal-Ansan Freeway were analyzed in this study to clarify the relationship. Hourly accident rate and V/C were calculated for each facility sections : basic freeway section, tunnel section and toll gate section. The accident rate models consisting of an independent variable of V/C were established by repression analysis and compared with each other. The relationship between accident rates and V/C ratios represented U-shaped pattern for all sections. The result of this study indicates that accident rates are highest in the low hourly V/C range, decrease with increasing V/C ratio, and then increase as the V/C ratio increases. The accident rate of toll gate section is in general higher than that of other sections. Although the accident rate of tunnel section is higher than that of basic freeway section when V/C is above 0.67, there is no significant difference of accident rate between basic freeway and tunnel section when V/C is between 0.5 and 0.8. Basic freeway tunnel and toll gate section have the minimum accident rate when V/C is 0.78, 0.75 and 0.57 respectively.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1692-1694
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• 2005

Spent nuclear fuel is reprocessed commercially by the chemical process to recover U and Pu. Recently, new salt-free reagents to separate plutonium and neptunium from uranium suitable for use in a single cycle flowsheet have been developed. Acetohydroxamic acid $(CH_3CONHOH)$ has been taken much interest in as a complexing agent capable of selective stripping of tetravalent actinides from U(VI) when actinides are present in the solvent stream of the advanced PUREX process. Additionally acetohydroxamic acid will rapidly reduce Np(VI) to inextractable Np(V) thus allowing the separation of Np from U. In this study, the rate equation for the reduction of Np(VI) to Np(V) in nitric acid aqueous solution has been determined as: $-[NpO_2^{2+}]$/dt = $k[NpO_2^{2+}]$[AHA] with k = 191.2 ${\pm}$ 11.2 $M^{-1}s^{-1}$ at 25 ${\pm}$ 0.5 ${^{\circ}C}$ and $[HNO_3]$ = 1.0 M. Comparison with other reductants available in the literature, acetohydroxamic acid is a strong one for $NpO_2^{2+}$.

• Journal of Oriental Neuropsychiatry
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• v.3 no.1
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• pp.84-90
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• 1992

Solvent and TLC-fractionations of the root of Salvia miltiorrhiza have yielded the results as follows ; Solvent fractions Petr. ether Ether Ethy1 acetate Water Control 100uL 0 0.2 35.1 41.9 43.0 50ul 0.7 3.7 37.2 42.0 TLC-fractionation and the Cytotoxic activity Fractions I II III IV V VI Petr. ehter Control 100uL13.0 7.1 16.8 1.2 30.9 23.2 0.5 48.3 50uL 37.1 26.1 30.0 20.1 45.7 27.2 29.7 Among the solvent fractions the petroleum ehter fraction corresponding to the concentration of 20ug/ml has showed the strongest Cytotoxic activity. (no cell survived) A double dilution of the fraction(10ug/ml) still showed strong activity.(0.2 cells survived) The ether fraction contained strong activity. Of the fraction which have veen obtained by a prcparative silicagel TLC I, II, III & IV were cytotoxic, but V and VI were inactive Howevcr, it is worthwhile to note that no one of these has no strong Cytotoxicity as the pertoleum ether fraction itself. This observation says that the active fractions could be additive or synergic to each other. The most active fraction, IV, was scrached out from the TLC and its UV-spectrum taken. The absorption maxima were 207 and 272 nm, indicating the presence of a flavanone strucuture.

• Journal of the Korean Mathematical Society
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• v.56 no.6
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• pp.1441-1461
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• 2019

In this paper we consider the monotonicity of the lowest constant ${\lambda}_a^b(g)$ under the Ricci-Bourguignon flow and the normalized Ricci-Bourguignon flow such that the equation $$-{\Delta}u+au\;{\log}\;u+bRu={\lambda}_a^b(g)u$$ with ${\int}_{M}u^2dV=1$, has positive solutions, where a and b are two real constants. We also construct various monotonic quantities under the Ricci-Bourguignon flow and the normalized Ricci-Bourguignon flow. Moreover, we prove that a compact steady breather which evolves under the Ricci-Bourguignon flow should be Ricci-flat.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.545-555
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• 2014

It has been previously demonstrated that laccases exhibit great potential for use in several industrial and environmental applications. In this paper, two laccase isoenzyme genes, lccB and lccC, were cloned and expressed in Pichia pastoris GS115. The sequence analysis indicated that the lccB and lccC genes consisted of 1,563 and 1,584 bp, and their open reading frames encoded 520 and 527 amino acids, respectively. They had 72.7% degree of identity in nucleotides and 86.7% in amino acids. The expression levels of LccB and LccC were up to 32,479 and 34,231 U/l, respectively. The recombinant laccases were purified by ultrafiltration and $(NH_4)_2SO_4$ precipitation, showing a single band on SDS-PAGE, which had a molecular mass of 58 kDa. The optimal pH and temperature for LccB were 2.0 and $55^{\circ}C$ with 2,2'-azinobis-[ 3-ethylbenzthiazolinesulfonic acid (ABTS) as a substrate, whereas LccC exhibited optimal pH and temperature at 3.0 and $60^{\circ}C$. The apparent kinetic parameters of LccB were 0.43 mM for ABTS with a $V_{max}$ value of 51.28 U/mg, and the Km and $V_{max}$ values for LccC were 0.29 mM and 62.89 U/mg. The recombinant laccases were able to decolorize five types of dyes. Acid Violet 43 (100 g/ml) was completely decolorized by LccB or LccC (2 U/ml), and the decolorization of Reactive Blue KN-R (100 g/ml) was 91.6% by LccC (2 U/ml). Thus, the study characterizes useful laccase isoenzymes from T. versicolor that have the capability of being incorporated into the treatment of similar azo and anthraquinone dyes from dyeing industries.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.458-461
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• 2015

In this paper 2 types of voltage references and a current reference suitable for low-voltage, low-power circuits are proposed and designed with $0.35{\mu}m\;CMOS$ process. MOS transistors operating in weak inversion and bulk-driven technique are utilized to achieve low-voltage and low-power features. The first voltage reference consumes 1.43uA from a supply voltage of 1.2V while it has a reference voltage of 585mV and a TC(Temperature Coefficient) of $6ppm/^{\circ}C$. The second voltage reference consumes 48pW from a supply voltage of 0.3V while having a reference voltage of 172mV and a TC of $26ppm/^{\circ}C$. The current reference consumes 246nA from a supply voltage of 0.75V with a reference current of 32.6nA and a TC of $262ppm/^{\circ}C$. The performances of the designed references have been verified through simulations.