• Title/Summary/Keyword: n. comb.

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Synthesis and Characterization of Comb-Type Grafted Polymer Hydrogels with Low Temperature Sensitivity (저온 감열 특성을 가지는 Comb-Type Grafted Polymer Hydrogels의 합성 및 특성평가)

  • Taek Kyu Jung;Sung Soo Kim;Byung Cheol Shin
    • Journal of the Korean Chemical Society
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    • v.47 no.1
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    • pp.59-66
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    • 2003
  • The comb-type grafted polymer hydrogels, which composed of N-isopropylacrylamide monomer and oligo(N-isopropylacrylamide-co-tert-butylacrylamide) [oligo(NIPAAm-co-t-BAM)], were synthesized by redox polymerization in 5~10% methanol aqueous solution using ammonium peroxodisulfate (APS) at 4 oC for 24h. The lower critical solution temperatures (LCSTs) of the comb-type grafted hydrogels were decreased with increase of t-BAM content in the grafted copolymer. We observed the effect of crosslinker and concentration of oligo(NIPAAm-co-t-BAM) on the shrinking/swelling ratio of hydrogels. Changes of shrinking/swelling ratio were decreased with increase of concentration of crosslinker. The increase of grafted oligo(NIPAAm-co-t-BAM) in the hydrogel shows an fast changes of shrinking/ swelling rate. The comb-type grafted hydrogels are expected to be valuable for the sensing materials of time-temperature labels(TTLs).

A Study on a Comb Filter Bank Circuit using B.B.D. (B.B.D.를 이용한 콤필터 뱅크회로에 관한 연구)

  • 이광형
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.7 no.4
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    • pp.156-160
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    • 1982
  • A Comb Filter(C.F.) is constucted with a N-stages one-dimensional B.B.D.(Bucket-Brigade Device) delay line. One channel of the B.P.F. (Band Pass Filter) Bank is experimented, which includes a R.F.(Recursie Filter) using S/H circuits cascaded to the C.F. This algorithm of the C.F.B.(Comb Filter Bank) becomes the parallel spectrum analyzer circuit. The algorithm has less number of multiplication than that of FFT and improves the SNR.

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Ten New Species of the Genus Falcileptoneta (Araneae, Leptonetidae) from Korea

  • Seo, Bo Keun
    • Korean Journal of Environmental Biology
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    • v.33 no.3
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    • pp.290-305
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    • 2015
  • Ten new species of the genus Falcileptoneta are described; Falcileptoneta bifurca n. sp., F. boeunensis n. sp., F. chiakensis n. sp., F. cornuta n. sp., F. digitalis n. sp., F. hansanensis n. sp., F. juwangensis n. sp., F. moakensis n. sp., F. naejangenesis n. sp., and F. unmunensis n. sp. And six species previously known as Leptoneta spiders are transferred to Falcileptoneta as fo11ows; Falcileptoneta coreana (Paik and Namkung, 1969), F. hwanseonensis (Namkung, 1987), F. secula (Namkung, 1987), F. simboggulensis (Paik, 1971), F. yebongsanensis (Kim, Lee and Namkung, 2004), and F. yongdamgulensis (Paik and Namkung, 1969), all n. comb.

The Antioxidative and Antimicrobial Effects of Celastrus orbiculatus (노박덩굴 추출물의 항산화 및 항균 효과)

  • Kang, Dae-Yeon;Shin, Mi-Ok;Shon, Jae-Hak;Bae, Song-Ja
    • Journal of Life Science
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    • v.19 no.1
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    • pp.52-57
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    • 2009
  • This study was carried out to investigate the antioxidative and antimicrobial activities of Celastrus orbiculatus (CO). CO was extracted with methanol and then further fractionated with n-hexane (COMH), butanol (COMB), methanol (COMM) or aqueous (COMA) to get active fractions. The antioxidative activity of fractions from CO was investigated by measuring the scavenging activities of CO against DPPH radical, peroxynitrite ($ONOO^-$) and reactive oxygen speicies (ROS). Among the various solvent fractions, the COMB showed a marked scavenging effect against DPPH radical, peroxynitrite ($ONOO^-$) and reactive oxygen species(ROS). The antimicrobial activity was increased in proportion to its concentration by the paper disk method. Among the various solvent fractions, the COMM and COMB fractions of CO showed strong antimicrobial activities. The results suggest that The CO may be suitable for development as a food preservative and alternative antioxidant.

Discharge Properties of an AC-Plasma Display Panel

  • Sungkyoo Lim
    • Journal of the Microelectronics and Packaging Society
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    • v.5 no.1
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    • pp.1-6
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    • 1998
  • Two kinds of the ac-plasma display panel (PDP) with the comb type and the matrix type electrodes were fabricated. The discharge properties were studied as a function of as species (Ne and Ne+He+Xe) and its pressure. The firing voltages (Vf) of the PDP with comb type electrodes were 159 V and 195 V under pure Ne and ne+He+Xe(68:30:2) gas mixture respectively. In case of PDP cell with the matrix type electrodes the Vf was increased to 200 V for pure Ne and 240 V for Ne+He+Xe gas mixture under the same gas pressure(300 mbar).

Fabrication of Polymeric Blend Membranes Using PBEM-POEM Comb Copolymer and Poly(ethylene glycol) for CO2 Capture (PBEM-POEM 공중합체와 Poly(ethylene glycol)의 폴리머 블렌드를 이용한 이산화탄소 분리막 제조)

  • Moon, Seung Jae;Min, Hyo Jun;Kim, Na Un;Kim, Jong Hak
    • Membrane Journal
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    • v.29 no.4
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    • pp.223-230
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    • 2019
  • In this paper, we develop a polymeric blend membrane based on $CO_2$-philic poly(2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] ethyl methacrylate)-poly(oxyethylene methacrylate) (PBEM-POEM) comb copolymer, which was synthesized by facile free radical polymerization. The PBEM-POEM (PBE) comb copolymer was blended with a commercial oligomer, low-molecular-weight poly(ethylene glycol) (PEG, $M_w=200gmol^{-1}$) with various ratios to prepare $CO_2/N_2$ separation membranes. From the result of $CO_2/N_2$ separation test of the PBE/PEG blend membranes with the various PEG contents, we could conclude that with increasing PEG content, the $CO_2/N_2$ selectivity significantly increased while the CO2 permeability decreased showing trade-off relationship. However, when comparing the performance of the PBE/PEG (9 : 1) with the PBE/PEG (7 : 3) membrane, the $CO_2$ permeance decreased by only 8.3%, while the $N_2$ permeance decreased by 69.1%. Therefore, the $CO_2/N_2$ selectivity dramatically increased from 33.8 to 100.3. This could be because the POEM chains, which account for 80% of the PBE copolymer, favorably interact with PEG and lead to a more compact chain structure, which was confirmed by FT-IR, XRD and SEM analysis. The PBE/PEG (7 : 3) blend membrane had the most optimal gas separation performance, showing a $CO_2$ permeance of 170.5 GPU and $CO_2/N_2$ selectivity of 100.3.

Design and Fabrication of Movable Micro-Fersnel Lens on XY-stage (XY-Stage에 의해 정적인 변위를 갖는 미세 프레넬 렌즈(Micro-Fresnel Lens)의 설계 및 제작)

  • Kim, Che-Heung;Ahn, Si-Hong;Lim, Hyung-Taek;Kim, Yong-Kweon
    • Proceedings of the KIEE Conference
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    • 1998.07g
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    • pp.2515-2517
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    • 1998
  • The micro fresnel lens(MFL) was modeled and fabricated on a XY-stage electrostatically driven by comb actuator. The modeled MFL was approximated as a step shape with 4-phase and 4-zone plate. The focal length and diameter of the MFL is 20mm and 912${\mu}m$, respectively. The XY-stage suspending the MFL is designed to generate a large static displacement up to about 20${\mu}m$. On SOI substrates, we first fabricated MFL using the RIE(reactive Ion etching) technology and then patterned and etched bulk silicon to make XY-stage. After the fabrication of all structures on top side of the SOI substrates. $Si_3N_4$ was deposited for passivation of all structures using PECVD(plasma enhanced chemical vapor deposition). All the MFL systems width comb drive actuator were released by KOH etching from the bottom side of the SOI wafer using double-sided alignment technique. In fabrication of MFL, a dry etching conditions is established in order to improve surface roughness and to control the etched depth.

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Implementation of Frequency Bandwidth Expander using VCO Drift Canceller and Comb generator (VCO 표류 성분 상쇄기와 빗쌀 하모닉 발생기를 이용한 주파수 대역 확장기의 구현)

  • 강승민
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.9B
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    • pp.1683-1689
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    • 1999
  • We have implemented Frequency bandwidth expander with frequency upconverting by VCO drift canceller and comb generator. Te output of the low frequency synthesizer which the output frequency is 220~280MHz(Resolution : 5MHz) is expanded to 1660~2140MHz by this system. The phase noise of this system only depends on the phase noise of comb generator and low frequency synthesizer. The phase noise of VCO don’t influence at the frequency expander because the drift of VCO cancel out. When we control the output of VCO, the output frequency of this system is varied by 60MHz x N as filter banker. The switching time and the spurious of the frequency expander is below 3usec, -55dBc respectively. This system easily expands bandwidth additively by expanding the output bandwidth of the VCO. We can apply the frequency expander to very wide band microwave synthesizer which has fast switching time.

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