• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.3
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• pp.179-192
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• 2008

A multiphase compensation method with mismatch linearization technique, is presented and demonstrated in a $\Sigma-\Delta$ fractional-N frequency synthesizer. An on-chip delay-locked loop (DLL) and a proposed delay line structure are constructed to provide multiphase compensation on $\Sigma-\Delta$ quantizetion noise. In the delay line structure, dynamic element matching (DEM) techniques are employed for mismatch linearization. The proposed $\Sigma-\Delta$ fractional-N frequency synthesizer is fabricated in a $0.18-{\mu}m$ CMOS technology with 2.14-GHz output frequency and 4-Hz resolution. The die size is 0.92 mm$\times$1.15 mm, and it consumes 27.2 mW. In-band phase noise of -82 dBc/Hz at 10 kHz offset and out-of-band phase noise of -103 dBc/Hz at 1 MHz offset are measured with a loop bandwidth of 200 kHz. The settling time is shorter than $25{\mu}s$.

• Bulletin of the Korean Chemical Society
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• v.6 no.1
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• pp.37-40
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• 1985

The electrical conductance and UV absorbance of 4,N-dimethyl Pridinium Iodide (NDMPI) were measured in the ethanol volume percentage, 95, 90, 80 and 60 of an ethanol-water mixture at 15, 25, 35 and $45^{\circ}C$. Ionic association constants(K) of NDMPI were evaluated in accordance with a combined method of conductance UV absorbance. The ion size parameter (${\gamma}_{\pm}$) and dipole momemt (${\mu}_{A+D-}$) of NDMPI were obtained from the values of K and dielectric constant. The ${\mu}_{A+D-}$- values were in good agreement with the values of transition moment(${\mu}_{mn}$) which is calculated form the UV peak values. The large negative values of the electrical enthalpy (${\Delta}H_{el}^{\circ}$) and entropy (${\Delta}H_{el}^{\circ}$ ) have proved that NDMPI had a positive hydration. The positive values of entropy (${\Delta}S^{\circ}$) means the formation of NDMPI ion goes with dehydration.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.271-273
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• 2005

The ${\delta}^{15}N\;and\;{\delta}^{15}O$ data of nitrate indicates the sources of nitrate in oxic groundwater as a mixture of ammonia or urea-containing fertilizer and manure. The ${\delta}^{34}S_{sulfate}$ values indicate that sulfate Is mainly originated from fertilizers and soil S. In sub-oxic groundwater, the increased ${\delta}^{34}S_{sulfate}$ values evidently indicate that sulfate is gradually removed by microbial mediated sulfate reduction. However, iron reduction does not occur In this study area. Such a reversed redox sequence may occur In the presence of stable iron oxides such as hematite and goethite in alluvlal aquifer.

• Restorative Dentistry and Endodontics
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• v.40 no.4
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• pp.255-261
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• 2015

Objectives: The aim of this study was to evaluate the effect of three different drinks on the color parameters of four different restorative materials. Materials and Methods: Three different composites (Filtek Ultimate Universal Restorative, Filtek Ultimate Flowable, and Filtek Silorane, 3M ESPE) and a polyacid-modified composite resin material (Dyract XP, Dentsply DeTrey GmbH) were evaluated. Eighty-four disc-shaped specimens of 8 mm in diameter and 2 mm in thickness were prepared (n = 21 each). Color coordinates ($L^*a^*b^*$, ${\Delta}L^*$, ${\Delta}a^*$, ${\Delta}b^*$, and ${\Delta}E^*$) were measured using a $V{\dot{I}}TA$ Easyshade Compact ($V{\dot{I}}TA$ Zahnfabrik) after 24 hr of storage (baseline) and after 30 day of storage in three different beverages of black tea, Coca cola, or water (control) (n = 7). In each beverage, the specimens were stored three times a day, one hr each, for 30 day. The color changes (${\Delta}E$) were calculated and were analyzed by Kruskal-Wallis and Dunn multiple comparison test. Results: The color difference (${\Delta}E^*$) of the resin materials ranged between 1.31 and 15.28 after 30 day of immersion in the staining solutions. Dyract XP in Coca cola ($15.28{\pm}2.61$) and black tea ($12.22{\pm}2.73$) showed the highest mean ${\Delta}E^*$ value after 30 day, followed by Filtek Ultimate Universal Restorative ($5.99{\pm}1.25$) and Filtek Ultimate Flowable ($4.71{\pm}1.40$) in black tea (p < 0.05). Conclusions: The compomers displayed unacceptable color changes at the end of 30 day in all beverages. Among resin composites, the silorane based composite exhibited relatively good color stability than the others. Filtek Ultimate Universal Restorative and Filtek Flowable showed similar color changes in all beverages.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.8
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• pp.387-391
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• 2006

The Ag photodoping effect in amorphous $As_{40}Ge_{10}Se_{15}S_{35}$ chalcogenide thin films for holographic recording has been investigated using a He-Ne laser (${\lambda}$=632.8 nm). The chalcogenide films thickness prepared in the present work were thinner in comparison with the penetration depth of recording light ($d_p=1.66{\mu}m$). It exhibits a tendency of the variation of the diffraction efficiency (${\eta}$) in amorphous chalcogende films, independently of the Ag photodoping. That is, ${\eta}$ increases rapidly at the beginning of the recording process and reaches the maximum (${\eta}_{max}$) and slowly decreases slowly with the exposed time. In addition, the value of ${\eta}_{max}$ depends strongly on chalcogenide film thickness(d) and its maximum peak among the films with d = 40, 80, 150, 300, and 633 nm is observed 0.083% at d = 150 nm (approximately 1/2 ${\Delta}n$), where ${\Delta}$n is the refractive index of chalcogenide thin film (${\Delta}n=2.0$). The ${\eta}$ is largely enhanced by Ag photodoping into the chakogenides. In particular, the value of ${\eta}_{max}$ in a bilayer of 10-nm-thick Ag/150-nm-thick $As_{40}Ge_{10}Se_{15}S_{35}$ film is about 1.6%, which corresponds to ${\sim}20$ times larger than that of the single-layer $As_{40}Ge_{10}Se_{15}S_{35}$ thin film (without Ag). And we obtained the diffraction pattern according to the formation of (P:P) polarization holographic grating using Mask pattern and SLM.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1555-1562
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• 2010

Development of the strain and the fermentation process of Hansenula polymorpha was implemented for the production of ${\gamma}$-linolenic acid ($GLA,\;C18:3{\Delta}^{6,9,12}$), an n-6 polyunsaturated fatty acid (PUFA) that has been reported to possess a number of health benefits. The mutated ${\Delta}^6$-desaturase (S213A) gene of Mucor rouxii was expressed in H. polymorpha under the control of the methanol oxidase (MOX) promoter. Without the utilization of methanol, a high-cell-density culture of the yeast recombinant carrying the ${\Delta}^6$-desaturase gene was then achieved by fed-batch fermentation under glycerol-limited conditions. As a result, high levels of the ${\Delta}^6$-desaturated products, octadecadienoic acid ($C18:2{\Delta}^{6,9}$), GLA, and stearidonic acid ($C18:4{\Delta}^{6,9,12,15}$), were accumulated under the derepression conditions. The GLA production was also optimized by adjusting the specific growth rate. The results show that the specific growth rate affected both the lipid content and the fatty acid composition of the GLA-producing recombinant. Among the various specific growth rates tested, the highest GLA concentration of 697 mg/l was obtained in the culture with a specific growth rate of 0.08 /h. Interestingly, the fatty acid profile of the yeast recombinant bearing the Mucor ${\Delta}^6$-desaturase gene was similar to that of blackcurrant oil, with both containing similar proportions of n-3 and n-6 essential fatty acids.

• Journal of Environmental Science International
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• v.28 no.1
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• pp.7-18
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• 2019

This study aimed to assess the impact of livestock excreta discharged from an Intensive Livestock Farming Area (ILFA) on river water quality during a rainfall event. The Bangcho River, which is one of the 7 tributaries in the Cheongmi River watershed, was the study site. The Cheongmi River watershed is the second largest area for livestock excreta discharge in Korea. Our results clearly showed that, during the rainfall event, the water quality of the Bangcho River was severely deteriorated due to the COD, $NH_4-N$, T-N, $PO_4-P$, T-P, and heavy metals (Cu, Zn, and Mn) in the run-off from nearby farmlands, where the soil comprised composted manure and unmanaged livestock excreta. In addition, stable isotope analysis revealed that most of nitrogen ($NH_4-N$ and $NO_3-N$) in the run-off was from the ammonium and nitrate in the livestock excreta. The values of ${\delta}^{15}N_{NH4}$ and ${\delta}^{15}N_{NO3}$ for the Bangcho River water sample, which was obtained from the downstream of mixing zone for run-off water, were lower than those for the run-off water. This indicates that there were other nitrogen sources upstream river in the river. It was assumed from ${\delta}^{15}N_{NH4}$ and ${\delta}^{15}N_{NO3}$ stable isotope analyses that these other nitrogen sources were naturally occurring soil nitrogen, nitrogen from chemical fertilizers, sewage, and livestock excreta. Therefore, the use of physicochemical characteristics and nitrogen stable isotopes in the water quality impact assessment enabled more effective analysis of nitrogen pollution from an ILFA during rainfall events.

• Journal of the Korean Chemical Society
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• v.46 no.3
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• pp.187-193
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• 2002

The reaction rates of substituted 6-chloroquinoline with p-substituted benzoyichorides $p-CH_3,$ p-H, $p-NO_2$ have been measured by conductometry in acetonitrile, and the constants are determined at various temperatures (10, 15, 20, $25^{\circ}C$) and pressures (1, 200, 500, 1000 bar). From the values of rate constants, the activation parameters (Ea, ${\Delta}V^{\neq}$, ${\Delta}H^{\neq}$, ${\Delta}S^{\neq}$, ${\Delta}G^{\neq}$) and the pressure dependence of Hammett p values were determined. The rate constants increased with increasing temperatures and pressures, and are further increased to introduction to the electron donor substiuents in substrate $(p-NO_2)$ with 6-chloroqinoline. When the activation volume and the activation entropy are all negative And the Hammett p values are positive for the substrate over the pressure and temperature range studied. The results of kinetic studies for pressure and substituent show that thease reactions proceed in typical $S_N2$ reaction mechanism and "associative $S_N2$" in bond formation favored with increasing pressures.

• Journal of the Korean Chemical Society
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• v.47 no.3
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• pp.206-212
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• 2003

The reaction rates of substituted quinolines (6-Clqui., qui.) with p-substituted benzoylchlorides $(p-CH_3,\;p-H,\;p-NO_2)$ have been measured by conductometry in acetonitrile, and the rate constants are determined at various temperatures (10, 15, 20, $25^{\circ}C$) and pressures (1, 200, 500, 1000 bar). From the values of rate constants, the activation parameters $(Ea,\;{\Delta}V^{\neq},\;{\Delta}H^{\neq},\;{\Delta}S^{\neq}, \;{\Delta}G^{\neq})$and the pressure dependence of Hammett ρ values were determined. The rate constants increased with increasing temperatures and pressures, and are further increased to introduction to the electron acceptor substituents in substrate $(p-NO_2)$ with quinoline. The activation volume and the activation entropy are all negative. And the Hammett p values are negative for nucleophile ${\rho}_X$ and positive for the substrate ${\rho}_Y$ over the pressure range studied. The results of kinetic studies for pressure and substituent show that these reactions proceed through a typical $S_N2$ reaction mechanism and "associative $S_N2$" favoring bond formation with increasing pressures.

• Journal of applied mathematics & informatics
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• v.25 no.1_2
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• pp.1-15
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• 2007

Consider a Rayleigh distribution with $$pdf\;p(x/{\theta})\;=\;2x{\theta}^{-1}\;{\exp}\;({-x^2}/{\theta})$$ and mean lifetime ${\mu}\;=\;\sqrt{\pi\theta}/2$. We study the two-action problem of testing the hypotheses $H_{0}\;:\;{\mu}{\leq}{\mu}_{0}$ against $H_{1}\;:\;{\mu}\;>\;{\mu}_{0}$ using a linear error loss of ${\mid}{\mu}\;-\;{\mu}_{0}{\mid}$ via the empirical Bayes approach. We construct a monotone empirical Bayes test ${\delta}^{*}_{n}$ and study its associated asymptotic optimality. It is shown that the regret of ${\delta}^{*}_{n}$ converges to zero at a rate $\frac{{\ln}^{2}n}{n}$, where n is the number of past data available when the present testing problem is considered.