• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1222-1225
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• 2004

This paper presents multibit Sigma-Delta ADC using noise-shaped dynamic element matching(DEM). 5-bit flash ADC for multibit quantization in Sigma Delta modulator offers the following advantages such as lower quantization noise, more accurate white-noise level and more stability over single quantization. For the feedback paths consisting of DAC, the DAC element should have a high matching requirement in order to maintain the linearity performance which can be obtained by the modulator with a multibit quantizer. The DEM algorithm is implemented in such a way as to minimize additional delay within the feedback loop of the modulator Using this algorithm, distortion spectra from DAC linearity errors are shaped. Sigma Delta ADC achieves 82dB signal to noise ratio over 615H7z bandwidth, and 62mW power dissipation at a sampling frequency of 19.6MHz. This Sigma Delta ADC is designed to use 0.25um CMOS technology with 2.5V supply voltage and verified by HSPICE simulation.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.2129-2131
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• 2011

• Journal of the Chungcheong Mathematical Society
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• v.20 no.4
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• pp.367-373
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• 2007

For a unital *-subalgebra of the space $\mathcal{L}^a(X)$ of all adjointable maps on a Hilbert $\mathcal{B}$-module X with a $C^*$-algebra $\mathcal{B}$, we study unitary operator (in such algebra)-valued multiplier ${\sigma}$ on a normal, generating subsemigroup S of a group G with its extension to G. A dilation of a projective isometric ${\sigma}$-representation of S is established as a projective unitary ${\rho}$-representation of G for a suitable unitary operator (in some algebra)-valued multiplier ${\rho}$ associated with the multiplier ${\sigma}$ which is explicitly constructed.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.468-473
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• 1999

This study was carried out to assess the use of RADARSAT data which is C-band with HH polarization for the rice growth monitoring in Korea. Nine time-series data were taken by shallow incidence angle (standard beam mode 5 or 6) during rice growing season. And then, backscatter coefficient ($\sigma$$^{\circ}$) were extracted by calibration process for comparing with rice growth parameters such as plant height leaf area index(LAI), and fresh and dry biomass. Field experimental data concerned with rice growth were collected 8 times for the ground truth at the study area, Tangjin, Chungnam, Korea. At the maximum vegetative stage of rice, backscatter coefficients were the highest at the flooded rice field ranging from -4.4dB~-3.1dB. The temporal variation of backscatter coefficient($\sigma$$^{\circ}$) in rice field was significant in this study Backscatter coefficient ($\sigma$$^{\circ}$) of rice field was a little bit lower again after heading stage. This results show RADARSTA data is promising for rice monitoring.

• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.55-55
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• 2002

An alternative sigma factor as encoded by the $\sigma$$\^$B/ gene in Streptomyces coelicolor A3(2) was known to be involved in the differentiation and osmotic stress response. Protein expression profiles of wild-type and a $\sigma$$\^$B/ mutant strain of S coelicolor A3(2), which is impaired in defense against osmotic stress, were compared in the absence and presence of osmotic stress, using 2-dimentional gel electrophoresis.(omitted)

• Journal of Microbiology and Biotechnology
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• v.3 no.3
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• pp.146-155
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• 1993

A DNA fragment from an alkali-tolerent Bacillus sp., conferring strong promoter activity, was subcloned into the promoter probe plasmid pPL703 and the nucleotide sequence of this promoter region was determined. The sequence analysis suggested that this highly efficient promoter region containing the complex clustered promoters comprised three kinds of promoters (P1, P2 and P3), which are transcribed by $\sigma^B (formerly \sigma^{37}), \sigma^E(formerly \sigma^{29}) and \sigma^A (formerly \sigma^{43})$ RNA polymerase holoenzymes which play major rules at the onset of endospore formation, during sporulation and at the vegetative phase of growth, respectively. S1 nuclease mapping experiments showed that all three promoters had staggered transcription initiation points. The results of chloramphenicol acetyltransferase assay after the subcloning experiments also indicated that the expression of these clustered promoters was correlated with the programs of growth and endospore development. Promoter P1, P2 and P3 were preceded by 75% AT, 79% AT and 81% AT regions, respectively, and a partial deletion of AT-rich region prevented transcription from promoter P1 in vivo. Two sets of 5 -AGTGTT-3 sequences and inverted repeat sequences located around the promoter P1 were speculated as the possible cis acting sites for the catabolite repression in B. subtilis. In vivo transcripts from these sequence regions may be able to form a secondary structure, however, the possibility that a regulatory protein induced by the excess amount of glucose could be bound to such a domain for crucial action remains to be determined.

• Journal of the Korean Society of Clothing and Textiles
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• v.25 no.3
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• pp.650-661
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• 2001

The purpose of this study is to suggest a guidance to select proper muslin through investigating fabric characteristics. The structural and physical properties of muslin and top fabric samples were tested by KES-FB system and other testers. And in order to examine the relation between fabric characteristics and the shape of garments, wearing tests were done with jackets made of those samples. As a result, bending rigidity(B), bending hysteresis(2HB), shear stiffness(G), shear hysteresis at=0.5(2HG), shear hysteresis at=5(2HG5), stiffness, cloth count/5cm, weight, thickness were extracted as the key factors affecting the appearance of garments. To have similar appearance, all of these should be counted. After standardizing, we calculate the variance between top cloth and muslin. And from this we could get the range that the proper muslin should be included. The ranges were as follows: Bending rigidity(B): within 0.024g.$\textrm{cm}^2$/cm(0.3$\sigma$); Shear stiffness(G): within 2.21g/cm.degree(1.3$\sigma$) Weight: within 9.33mg/$\textrm{cm}^2$(18$\sigma$); Thickness: within 0.20mm(1.8$\sigma$)

• Bulletin of the Korean Mathematical Society
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• v.41 no.3
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• pp.483-492
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• 2004

Let : [0, 1] $\times$ [0, $\infty$) $\longrightarrow$ [0, $\infty$) be continuous and a ${\in}$ C([0, 1], [0, $\infty$)),and let ${\xi}_{i}$ $\in$ (0, 1) with 0 < {\xi}$_1$ < ${\xi}_2$ < … < ${\xi}_{m-2}$ < 1, $a_{i}$, $b_{i}$ ${\in}$ [0, $\infty$) with 0 < $\Sigma_{i=1}$ /$^{m-2}$ $a_{i}$ < 1 and $\Sigma_{i=1}$$^{m-2}$ < l. This paper is concerned with the following m-point boundary value problem: $\chi$″(t)＋a(t) (t.$\chi$(t))＝0,t ${\in}$(0,1), $\chi$'(0)＝$\Sigma_{i=1}$ $^{m-2}$ /$b_{i}$$\chi$'(${\xi}_{i}$),$\chi$(1)＝$\Sigma_{i=1}$$^{m-2}$$a_{i}$$\chi$(${\xi}_{i}$). The existence, multiplicity and uniqueness of positive solutions of this problem are discussed with the help of two fixed point theorems in cones, respectively.

• 한국지형공간정보학회:학술대회논문집
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• 2002.03a
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• pp.48-53
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• 2002

본 연구에서는 각각 1998년 8월 12일(홍수 발생시), 8월 19일(홍수 발생 후) 옥천, 보은 지역을 촬영한 RADARSAT SAR 위성영상을 이용하여 수계지역 및 홍수지역 분류를 수행하고자 하였다. 이를 위해, 먼저 두 장의 위성영상에 대해서 각각 스페클 잡영(speckle noise)을 제거하고, ${\sigma}^0$(sigma naught, dB)을 계산한 후 수계지역에 대한 ${\sigma}^0$값을 분석하였다. 이 값을 기준으로 각각 두 장의 위성영상에서 각각 최대우도법을 이용하여 수계지역을 분류하였다. SAR 영상은 영상취득의 원리에 의해 지형의 기복에 따른 음영효과(shadow effect)가 발생하는데, 음영효과가 발생하는 지역의 ${\sigma}^0$값은 수계지역과 비슷한 반사특성(낮은 dB 값)을 보인다. 따라서 지형의 기복이 심한 지역의 수계지역 분류시 음영효과를 제거해야 효과적적인 분류를 할 수 있으며, 이를 위해 위성의 헤더자료로부터 촬영시 각각의 촬영중심을 계산하고, 촬영중심과 지상좌표와의 기하학적 관계를 고려하여 음영효과를 제거하였다. 마지막으로, 수계지역만이 추출된 영상에 대해 영상의 기하보정을 수행하였으며, 기하 보정된 두장의 위성영상에 대해 차분영상를 생성함으로서 홍수지역을 분류하였다.

• Journal of the Korean Chemical Society
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• v.37 no.1
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• pp.148-153
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• 1993

The Wallach rearrangement of 4'-halogenated azoxybenzenes in strong sulfuric acid was reinvestigated by UV-Vis spectrophotometric method. Interestingly an excellent linearity $(logk_{obs}=-0.61\;{\sigma}_R{^+} -3.29,\;{\gamma = 0.998)$ was obtained on plotting log (rate) vs. substituent constant, ${\sigma}_R{^+}$, which is known as the Pi delocalization parameter. Thus B-H mechanism via a charged intermediate $(DC^{++})$, which can be largely stabilized by resonance, is far more favored for the Wallach rearrangement.