• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.1
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• pp.10-17
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• 2012

This paper presents a clock regenerator using two $2^{nd}$ order ${\sum}-{\Delta}$ (sigma-delta) modulators for wide range of dividing ratio as defined in HDMI standard. The proposed circuit adopts a fractional-N frequency synthesis architecture for PLL-based clock regeneration. By converting the integer and decimal part of the N and CTS values in HDMI format and processing separately at two different ${\sum}-{\Delta}$ modulators, the proposed circuit covers a very wide range of the dividing ratio as HDMI standard. The circuit is fabricated using 0.18 ${\mu}m$ CMOS and shows 13 mW power consumption with an on-chip loop filter implementation.

• The Korean Journal of Food And Nutrition
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• v.11 no.6
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• pp.635-639
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• 1998

The thermal degradation pattern of $\alpha$-, ${\gamma}$-and $\delta$-tocopherols in glycerol was investigated during heating at 100~25$0^{\circ}C$ for 5-60 min in the absence of oxyge. The tocopherols and thermally decomposed products were separated by HPLC with a reversed phase $\mu$-Bondapak C18-column. The degradation pattern of $\alpha$-tocopherol during the heating in the absence of oxygen was different from those of ${\gamma}$-and $\delta$-tocopherols. But the degradation patterns of ${\gamma}$-and $\delta$-tocopherols were similar to each other. The residual content of $\alpha$-tocopherol during the heating in the absence of oxygen decreased to the range 12~65% and those of ${\gamma}$-and $\delta$-tocopherols decreased to the range 4~96%. The thermal degradation of tocopherols in the absence of oxygen was less than that in the presence of oxygen.

• Korean Journal of Materials Research
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• v.16 no.8
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• pp.466-472
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• 2006

The electrical, dielectric properties, and its stability of ZPCCL-based varistors were investigated for different sintering temperatures in the range of $1230{\sim}1300^{\circ}C$. As the sintering temperatures increased, the varistor voltage decreased in the range of $777.9{\sim}108$ V/mm, the nonlinear coefficient decreased in the range of $77.9{\sim}7.1$, and the leakage current increased in the range of $0.3{\sim}50.6\;{\mu}A$. The stability of electrical and dielectric characteristics was obtained from sintering temperature of $1260^{\circ}C$. the varistors sintered at $1260^{\circ}C$ marked the high electrical and dielectric stability, with $%{\Delta}{V_{1mA}=+1.9%,\;%{\Delta}{\alpha}=-10.6%,\;%{\Delta}I_L=+20%\;and\;%{\Delta}tan\;{\delta}=+9.9%$ for DC accelerated aging stress state of $0.95V_{1mA}/150^{\circ}C$/24 h.

• Membrane and Water Treatment
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• v.10 no.5
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• pp.321-330
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• 2019

The objective of this study was to examine the recovery of the power plant cooling tower blowdown water (CTBD) by membrane distillation. The experiments were carried out using a flat plate poly vinylidene fluoride (PVDF) membrane with a pore diameter of $0.22{\mu}m$ by a direct contact membrane distillation unit (DCMD). The effects of operating parameters such as transmembrane temperature difference (${\Delta}T$), circulation rate and operating time on permeate flux and membrane fouling have been investigated. The results indicated that permeate flux increased with increasing ${\Delta}T$ and circulation rate. Whereas maximum permeate flux was determined as $47.4L/m^2{\cdot}h$ at ${\Delta}T$ of $50^{\circ}C$ for all short term experiments, minimum permeate flux was determined as $7.7L/m^2{\cdot}h$ at ${\Delta}T$ of $20^{\circ}C$. While $40^{\circ}C$ was determined as the optimum ${\Delta}T$ in long term experiments. Inorganic and non-volatile substances caused fouling in the membranes.

• Bulletin of the Korean Mathematical Society
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• v.33 no.1
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• pp.57-64
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• 1996

Let $(X, B, \mu)$ be a probability space. Then we say $\tau : X \to X$ is a measure-preserving transformation if $\mu(\tau^{-1} E) = \mu(E)$. and we call it an ergodic transformation if $\mu(\tau^{-1}E\DeltaE) = 0$ for a measurable subset E implies $\mu(E) = 0$. An equivalent definition is that constant functions are the only $\tau$-invariant functions.

• Korean Journal of Materials Research
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• v.13 no.3
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• pp.200-204
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• 2003

A statistical experiment method was employed to investigate the window of the thermal stability of $TiSi_2$films which are popular for Ti-salicide and ohmic layers. The statistical experimental results showed that the first order term of $TiSi_2$thickness and annealing temperature was acceptable as a function of $\Delta$resistivity by 95% reliability criteria, and R-sq value implying a fit accuracy of the model also showed a high value of 93.80%. We found that $\Delta$resistivity of the $TiSi_2$film annealed at $700^{\circ}C$ for 1 hr changed from 3.35 to $0.379\mu$$\Omega$$\cdot$cm with increasing thickness from 185 to $703\AA$, and TEX>$\Delta$resistivity of the $TiSi_2$film with a fixed thickness of 444 $\AA$ changed from 0.074 to 17.12 $\mu$$\Omega$$\cdot$cm with increasing temperature increase from 600 to $800^{\circ}C$. From these results, we report that the process conditions of$ 692^{\circ}C$-1 hr, $715^{\circ}C$-1 hr, and 73$0^{\circ}C$-1 hr for $TiSi_2$($400 \AA$) are stable by the criteria of 1, 2, and 3 $\mu$$\Omega$$\cdot$cm of $\Delta$resistivity, respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.4
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• pp.393-403
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• 2008

In an effort to estimate secondary $PM_{10}$ concentrations and their diurnal variations at different photochemical activities, $PM_{10}$, CO, and $O_3$ concentrations obtained from the ambient air quality network located in Seoul are analyzed for the period from 2000 to 2005. In order to classify the photochemical activities on a daily basis, measured ${\Delta}O_{3,\;max-min}$ (maximum $O_3$-minimum $O_3$) and ${\int}(hv)dt$ which represents accumulated daily insolation, were used to classify each day into three regimes: 1) low photochemical reactivity; ${\Delta}O_{3,\;max-min}\;{\leq}\;40\;ppb$, and ${\int}(hv)dt\;{\leq}\;4000\;W/m^2$, 2) moderate photochemical reactivity; $40\;ppb\;<\;{\Delta}O_{3,\;max-min}\;{\leq}\;60\;ppb$, and $4000\;{\leq}\;{\int}(hv)de\;{\leq}\;6000\;W/m^2$, and 3) high photochemical reactivity; ${\Delta}O_{3,\;max-min}\;>\;60\;ppb$, and ${\int}(hv)dt\;{\geq}\;6000\;W/m^2$. The ratio of ($PM_{10}$/CO) obtained at low photochemical activity regime was used as an index of tracer for the estimation of secondary $PM_{10}$ at higher photochemical activity regimes. The results show that the estimated secondary $PM_{10}$ concentrations for moderate and high photochemical regimes are found to be 18.8% ($10.9\;{\mu}g/m^3$), and 35.0% ($26.2\;{\mu}g/m^3$), respectively. Diurnal variation of secondary $PM_{10}$ for the moderate photochemical regime shows weak but noticeable patterns. However, the highly activated photochemical regime shows strong diurnal variations of secondary $PM_{10}$ concentrations with the maximum value of $35.1\;{\mu}g/m^3$ at 1300LST.

• Journal of the Korean Ceramic Society
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• v.34 no.10
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• pp.1074-1082
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• 1997

Microstructure and permeability as a function of sintering temperature and composition were studied on the Ni$\delta$Cu0.4-$\delta$Zn0.6Fe2O4 ($\delta$=0, 0.1, 0.2, 0.3, 0.4) which was prepared by Cu2+ substitution for Ni2+ in Ni.0.4Zn0.6Fe2O4, then followed by 8 wt% CuO and 1wt% Bi2O3 as sintering aids. It was found that NiCuZn ferrite in which Cu2+ is substituted for Ni2+ is more effective in reduction of sintering temperature than Ni.0.4Zn0.6Fe2O4, containing CuO as a sintering aid. The specimen $\delta$=0.2 sintered at 90$0^{\circ}C$ for 2hr exhibited the highest initial permeability value ($\mu$o=280 at 1Mhz), but the real permeability decreased at the frequency under 10 MHz. EPMA analysis showed that Ni$\delta$Cu0.4-$\delta$Zn0.6Fe2O4 ($\delta$=0.4), sintered at 95$0^{\circ}C$ for 2hrs consisted of three phase regions of Ni.0.3Cu0.1Zn0.6Fe2O4 region, Cu and Bi liquid existed at the 3-point boundary, although the stabilization energy of Ni2+ is higher than that of Cu2+ in B site.

• Journal of Ginseng Research
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• v.34 no.3
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• pp.219-226
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• 2010

In the present study, we investigated whether a gross deletion in the nef gene ($g{\Delta}nef$) is induced by Korean red ginseng (KRG) intake. Ten patients were treated with KRG powder for 3 years in the absence of antiretroviral drug therapy. On average, $3,555{\pm}1,042\;g$ KRG was administered per person over $36.1{\pm}2.4$ months. There was a mild decrease in CD4 T cell count ($75{\pm}110/{\mu}L$) over the $36.1{\pm}2.4$ months (p = 0.059). We obtained 355 nef amplicons using 71 peripheral blood mononuclear cell samples over a 3-year period. All ten patients exhibited g${\Delta}$nef (range, 3.2 to 45.9%). At baseline, 3 of 78 amplicons (3.8%) exhibited $g{\Delta}nef$, whereas 18.8% (52/277) revealed $g{\Delta}nef$ during KRG-intake (p<0.001). The proportion of $g{\Delta}nef$ was significantly correlated with monthly dose of KRG (r=0.89, p<0.001). The median time for first detection of $g{\Delta}nef$ was 13 months. In conclusion, our data show that $g{\Delta}nef$ is inducible by KRG intake and its proportion is dependent on the duration of KRG intake and dose of KRG.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.2
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• pp.446-450
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• 2011

Tunable SC(Switched Capacitor) bandpass ${\Sigma}-{\Delta}$(Sigma-Delta) modulator used in wireless system receiver occurs a signal attenuation according to tuning of center frequency in signal bandwidth. In this paper, tunable bandpass 4th order SC bandpass ${\Sigma}-{\Delta}$ modulator with novel structure is proposed for rejection of signal attenuation in signal bandwidth. The existing structure uses a ten variable coefficient values for rejection of signal reduction in the modulator. But the proposed structure only use a two variable coefficient values for rejection of signal attenuation in the modulator. Also, an adder and comparator is replaced with a comparator having 4 inputs in the modulator. Therefore, the existing structure has one more OP-AMP. The purposed modulator was designed in $0.18\;{\mu}m$ CMOS technology. The resolution of the modulator within 310 kHz bandwidth and 40 MHz sampling frequency under 6.67 MHz, 10 MHz and 13.33 MHz intermediate frequency are over 10 bit.