• Title/Summary/Keyword: Sigma-delta

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Architecture Improvement of Analog-Digital Converter for High-Resolution Low-Power Sensor Systems (고해상도 저전력 센서 시스템을 위한 아날로그-디지털 변환기의 구조 개선)

  • Shin, Youngsan;Lee, Seongsoo
    • Journal of IKEEE
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    • v.22 no.2
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    • pp.514-517
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    • 2018
  • In sensor systems, ADC (analog-to-digital converter) demands high resolution, low power consumption, and high signal bandwidth. Sigma-delta ADC achieves high resolution by high order structure and high over-sampling ratio, but it suffers from high power consumption and low signal bandwidth. SAR (successive-approximation-register) ADC achieves low power consumption, but there is a limitation to achieve high resolution due to process mismatch. This paper surveys architecture improvement of ADC to overcome these problems.

A Delta-Sigma Fractional-N Frequency Synthesizer for Quad-Band Multi-Standard Mobile Broadcasting Tuners in 0.18-μm CMOS

  • Shin, Jae-Wook;Kim, Jong-Sik;Kim, Seung-Soo;Shin, Hyun-Chol
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.7 no.4
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    • pp.267-273
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    • 2007
  • A fractional-N frequency synthesizer supports quadruple bands and multiple standards for mobile broadcasting systems. A novel linearized coarse tuned VCO adopting a pseudo-exponential capacitor bank structure is proposed to cover the wide bandwidth of 65%. The proposed technique successfully reduces the variations of KVCO and per-code frequency step by 3.2 and 2.7 times, respectively. For the divider and prescaler circuits, TSPC (true single-phase clock) logic is extensively utilized for high speed operation, low power consumption, and small silicon area. Implemented in $0.18-{\mu}m$ CMOS, the PLL covers $154{\sim}303$ MHz (VHF-III), $462{\sim}911$ MHz (UHF), and $1441{\sim}1887$ MHz (L1, L2) with two VCO's while dissipating 23 mA from 1.8 V supply. The integrated phase noise is 0.598 and 0.812 degree for the integer-N and fractional-N modes, respectively, at 750 MHz output frequency. The in-band noise at 10 kHz offset is -96 dBc/Hz for the integer-N mode and degraded only by 3 dB for the fractional-N mode.

Study on the Temperature and the Origin of Mineralization at the Samkwang Au Deposits (삼광(三光) 금(金) 광상(鑛床)의 광화(鑛化) 온도(溫度) 및 근원(根源)에 관關(한) 연구(硏究))

  • Moon, Kun Joo
    • Economic and Environmental Geology
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    • v.19 no.1
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    • pp.19-24
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    • 1986
  • The Samkwang mine is one of gold deposits distributed mainly in the southwestern province (Chungnam) of the Korean peninsula. Golds occur in quartz veins aged of $223{\pm}4MA$ according to K-Ar age dating from muscovite in a pegmatitic quartz vein. Quantz veins intrude Precambrian biotite-granite gneiss and mica schist of unknown age. Fluid inclusions in the quartz show a range of homogenization temperatures from 159 to $274^{\circ}C$. A calculated temperature from the isotopes of the galena-sphalerite pair is $375^{\circ}C$. Two phases-fluid inclusions homogenized either by liquid or vapor phase are frequently observed in specimens over $260^{\circ}C$, which may indicate the boiling of the fluids. Pressure of formation of the quartz veins inferred by the homogenization temperatures of liquid-$CO_2$ bearing fluid is 1kb. Based on these data, it is assumed that the temperature of the formation of the Samkwang mine may lie in between $350^{\circ}-230^{\circ}C$. ${\delta}^{34}S_{{\Sigma}s}$ values of sulphide minerals show narrow range of +2.1 to +4.6, and show a trend of enrichments of $^{34}S$ in the fluid from deep to the surface. ${\delta}^{34}S_{{\Sigma}s}$ in the fluid estimated is less than 3 permil, suggesting sulphur fluid originated from the magma.

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Evaluation of Atmospheric Stability Classification Methods for Practical Use (대기안정도 분류방법의 평가 및 실용화에 관한 연구)

  • 김정수;최덕일;최기덕;박일수
    • Journal of Korean Society for Atmospheric Environment
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    • v.12 no.4
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    • pp.369-376
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    • 1996
  • Major atmospheric stability classification methods were evaluated with meteorological data obtained by scoustic sounding profiler (SODAR/RASS) in Seoul. The Psequill classificatio method, the method most widely used because of its good agreement in respect of synoptic scope under the steady state, fails to describe the time lag, the response time on stability by heating or cooling caused by daily insolation or noctrunal surface radiation. Horizontal and vertical standard deviation of wind fluctuation $(\sigma_A and \sigma_E)$ method tend to classify night-time stable condition (E, F class) into unstable condition (A, B class). The classification matrix tables for Vogt's vertical temperature difference and wind speed using method ($\Delta$T $\cdot$ U) and bulk Richardson number (Rb) were amended for practical use over Seoul. The modified tables for $\Delta$T $\cdot$ U and Rb method were made by using comprehensive frequency distribution from Pasquill's method and other existing results, and the correlation coefficient(r) was equal to 0.829. It was confirmed that atmospheric stability could be changed with monitoring site characteristics, height and vertical difference between sensors of monitoring station, and classification method itself.

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The Design of Decimation Filters for High Precision Digital Audio Using FIR and IIR Filters (FIR과 IIR 필터를 이용한 고정밀 디지털 오디오용 데시메이션 필터 설계)

  • 신건순
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.4
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    • pp.630-638
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    • 2001
  • This paper has been proposed a structure composed of FIRs and IIR filters as digital decimation filter to compensate the drooping inband on the high precision AU chips. The area of chip has been reduced compared with the conventional structure because the RAM and MAC is reduced. The passband ripple$(\leq\; 0.4535 \times fs)$, passband attenuation(at $\; 0.4535 \times fs$ and stopband attenuation$(\geq\; 0.59\times fs)$ of the 6th-order $\Delta\Sigma$ modulator and digital decimation filter had $\pm0.0007[dB]$, -0.0013[dB] and -110[dB] respectively. Also the inband group delay, which was almost same compared with the conventional digital decimation filter structure, was 30.07/fs[s] band the error of group delay was 0.1672%.

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ON HARMONICITY IN A DISC AND n-HARMONICITY

  • Lee, Jae-Sung
    • Bulletin of the Korean Mathematical Society
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    • v.47 no.4
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    • pp.815-823
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    • 2010
  • Let ${\tau}\;{\neq}\;\delta_0$ be either a power bounded radial measure with compact support on the unit disc D with $\tau(D)\;=\;1$ such that there is a $\delta$ > 0 so that ${\mid}\hat{\tau}(s){\mid}\;{\neq}\;1$ for every $s\;{\in}\;\Sigma(\delta)$ \ {0,1}, or just a radial probability measure on D. Here, we provide a decomposition of the set X = {$h\;{\in}\;L^{\infty}(D)\;{\mid}\;lim_{n{\rightarrow}{\infty}}\;h\;*\;\tau^n$ exists}. Let $\tau_1$, ..., $\tau_n$ be measures on D with above mentioned properties. Here, we prove that if $f\;{in}\;L^{\infty}(D^n)$ satisfies an invariant volume mean value property with respect to $\tau_1$, ..., $\tau_n$, then f is n-harmonic.

The study on the weldability of STS 304 thin sheet by GTAW Process (STS 304 극박판의 TIG 용접성에 관한 연구)

  • 정호신;성상철;박영대
    • Proceedings of the KWS Conference
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    • 1998.05a
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    • pp.150-154
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    • 1998
  • The purpose of this paper is to investigate optimum welding conditions of STS 304 thin sheet by GTA welding and control 6 $\delta$--fenite which is harmful in mechanical processing, corrosion problem and can be formed brittle a phase in using long term at high temperature. One series of automatic welds was made using argon plus 10, 20, 30 % nitrogen to ensure a fully austenite deposit. Results obtained were summarized as follows: 1) 6 $\sigma$ferrite content in the weld metals is influenced largely by the nitrogen content. 2) Additions of nitrogen to the shielding gas can significantly reduce the amount of retained delta ferrite and result in an increase in hot cracking. 3) Bead width was increased when Ar + $N_2$ shielding gas was used and travel speed was increased. 4) Ar+$N_2$ shielding gas made weld metal ductile and reduce 6 -$\delta$-ferrite.

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A Study on Fatigue Design for Welded Joint of STS301L (STS301L 용접종류별 이음재의 피로설계에 관한 연구)

  • Baek, Seung-Yeb
    • Journal of Welding and Joining
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    • v.28 no.3
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    • pp.86-91
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    • 2010
  • Stainless steel sheets are widely used as the structural material for the railroad cars and the commercial vehicles. These kinds structures used stainless steel sheets are commonly fabricated by using the gas welding. For fatigue design of gas welded joints such as fillet and plug type joint, it is necessary to obtain design information on stress distribution at the weldment as well as fatigue strength of gas welded joints. And also, the influence of the geometrical parameters of gas welded joints on stress distribution and fatigue strength must be evaluated. the ${\Delta}P-N_f$ curves were obtained by fatigue tests. Using these results, ${\Delta}P-N_f$ curves were rearranged in the ${\Delta}{\sigma}-N_f$ relation with the maximum stress at the edge of fillet welded joint.

A Study on Fatigue Design for Welded Joint of STS301L (STS301L 용접이음재의 피로설계에 관한 연구)

  • Baek, Seung-Yeb
    • Transactions of the Korean Society of Automotive Engineers
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    • v.18 no.4
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    • pp.127-131
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    • 2010
  • Stainless steel sheets are widely used as the structural material for the railroad cars and the commercial vehicles. These kinds of structures used stainless steel sheets are commonly fabricated by using the gas welding. For fatigue design of gas welded joints such as fillet and plug type joint, it is necessary to obtain design information on stress distribution at the weldment as well as fatigue strength of gas welded joints. And also, the influence of the geometrical parameters of gas welded joints on stress distribution and fatigue strength must be evaluated. Thus, in this paper, ${\Delta}P-N_f$ curves were obtained by fatigue tests. Using these results, ${\Delta}P-N_f$ curves were rearranged in the. ${\Delta}{\sigma}-N_f$ relation with the hot spot stresses at the gas welded joints.

MO Studies on (4 + 2) Cycloadditions of Substituted-Arenediazocyanides and Nitrosobenzenes (치환체-Arendiazocyanide, Nitrosobenzene의 (4 + 2) 고리첨가 반응에 대한 분자궤도론적 연구)

  • Gu Cheun Chung;Seong Kyu Park;Il Doo Kim;Ikchoon Lee
    • Journal of the Korean Chemical Society
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    • v.28 no.5
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    • pp.284-292
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    • 1984
  • This paper aims to predict the substituent and Lewis acid catalysis effect or reactivity on the regioselectivity of (4+2) cycloaddition reaction of the substituted-E-arene-diazocyanides and nitrosobenzenes. Frontier orbital theory (FMO) has been applied to thermal and catalyzed Diels-Alder reaction by means of CNDO/2 and EHT-SPD methods. It has been found that: (1) The above reaction is positive rho(${\rho}$) values in Hammett equation, so it takes normal electron demand reaction, and four-frontier orbitals and Anh methods are identical with experimental major regioisomer.(2) When electron withdrawing radicals are substituted HOMO and LUMO energies of dienophiles are reduced, and the reactivity is increased. (3) The major regioisomer is predicted as B type, as the Lewis acid makes complexes of dienophile, and polaries LUMO coefficients of dienophile in an opposite way. (4) The linear correlation of Hammett is indicated in the graph of stabilized energies(${\Delta}$E) and sigma(${\sigma}$).

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