• Title, Summary, Keyword: PAM

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Preparation of Cellulose Graft Copolymers as Super Water Absorbents(II)-Water and Moisture Sorptive Properties of Super Water Absorbents Prepared from Low Cyanoethylated Wood Pulp-g-PAM- (고흡수성 재료로서 셀룰로오스계 그라프트 고분자의 제조(II) - 저치환 시아노에틸화 목재 펄프-g-PAM으로부터 제조한 고흡수성 고분자의 흡수 및 흡습성 -)

  • 김재필;문성필
    • Textile Science and Engineering
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    • v.33 no.8
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    • pp.722-728
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    • 1996
  • The water and moisture sorptive properties of the super water absorbents(H-LCE-WP-g-PAM) prepared from low cyanoethylated wood pulp(LCE-WP) were investigated. The H-LCE-WP-g-PAM showed remarkably higher equilibrium water absorbency than a commercial absorbent, although the latter absorbed water more rapidly. The absorbency of H-LCE-WP-g-PAM in bivalent salt solutions was lower than that in monovalent salt solution of same concentration. Phase transitions of the H-LCE-WP-g-PAM were not detected clearly in methanol/water mixtures of various composition. The absorbency of H-LCE-WP-g-PAM was highly dependent on the pH of the solution. H-LCE-WP-g-PAM exhibited the maximum absorbency at pH 7, and it decreased sharply with increasing of acidity and basicity. On the other hand, temperature dependence of the absorbency was not noticeable in the range of 5~8$0^{\circ}C$ tested in this study. H-LCE-WP-g-PAM absorbed moisture fast in the early stage.

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A 6.4-Gb/s/channel Asymmetric 4-PAM Transceiver for Memory Interface

  • Lee, Kwang-Hun;Jang, Young-Chan
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.129-131
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    • 2011
  • An 6.4-Gb/s/channel 4-PAM transceiver is designed for a high speed memory application. The asymmetric 4-PAM signaling scheme is proposed to increase the voltage and time margins, and reduces the reference noise effect in a receiver by 33%. To reduce ISI in a channel, 1-tap pre-emphasis of a transmitter is used. The proposed asymmetric 4-PAM transceiver was implemented by using 0.13um 1-poly 6-metal CMOS process with 1.2V supply. The active area and power consumption of 1-charmel transceiver including a PLL are $0.294um^2$ and 6mW, respectively.

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Simulation of Alpine Field Soil Loss by Outdoor Rainfall Simulator (실외인공강우에 의한 경사밭의 토양 유실량 모의)

  • Shin, Hyun-Jun;Won, Chul-Hee;Kim, Tae-Yoo;Choi, Eu-Tteum;Choi, Joong-Dae
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.1242-1246
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    • 2010
  • 호우기간 동안 내리는 빗방울의 타격에 의해 흙 입자는 침출수와 함께 이동하여 지표 아래 공극을 막는다. 다져진 지표면은 유출과 토양 유실의 원인이 된다. 발생원으로부터 유실되는 토양을 Polyacrylamide(PAM)과 지표피복재를 이용하여 저감하는 연구를 하였다. PAM은 토양 입자의 결합력을 강화시키고 이탈을 방지하여 토양 유실을 감소시키는데 효과적이다. 이 연구의 목적은 PAM을 덧붙인 볏짚거적, 볏짚거적+톱밥, 볏짚거적+왕겨 등을 이용하여 인공강우 동안 토양 유실을 저감하는 효과를 조사하는 것이다. 실험은 1시간 동안 강우를 모의했으며, 실험 도중에 6~7회 수질 샘플을 채취하였다. 초기유출시간은 총 4차 실험중에 2차를 제외한 나머지에서 볏짚거적+왕겨+PAM이 가장 느리게 유출되었다. SS와 탁도 항목에서 1차 실험을 제외한 나머지 실험에서 볏짚거적+톱밥+PAM이 효과적이었다. 단순히 PAM을 사용하는 것보다 잔여물(residue)을 같이 혼합한 피복재료가 토양 유실과 유출을 저감하는데 더욱 효과적인 것으로 나타났다. 본 연구 결과는 향후 농촌지역에 토양 유실저감에 필요한 자료로 활용할 수 있을 것이라 판단된다.

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User Authentication by using SMART CARD and PAM (스마트 카드와 PAM을 이용한 사용자 인증)

  • 강민정;강민수;박연식
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.637-640
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    • 2003
  • Authentication between Server and Client is necessary in most of Internet Service because of increasing of using of Internet. Unix-based Server upgraded security of user authentication using "Shadow Password" instead of "crypt" function. But "Shadow Password" most use same authentication method about all services. But we individually can set user authentication method using PAM(Pluggable Authentication Module). This paper will propose user authentication system using Linux-PAM that use SMART CARD as authentication token.

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Timing Recovery Algorithm with Slop Compensated for Multi-level PAM Signals (Multi-level PAM신호에 적용 가능한 기울기 보상 심볼타이밍 알고리즘)

  • 전광호;임명섭
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.26 no.11A
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    • pp.1864-1871
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    • 2001
  • In this paper, new symbol timing recovery algorithm is proposed, which is suitable for the digital communication system with Multi-level PAM signals. In the newly proposed symbol timing recovery algorithm, the timing error function is derived by compensating the several difference values between sampled symbol and neighboring symbol every symbol period with mid samples and decided symbol values. Conventional symbol timing recovery methods did not work well in Multi-level PAM signals, but the newly proposed method can be applied to Multi-level PAM signals as well as QPSK. For the performance analysis, the derived variance of the timing error function and the timing error characteristics of S-curve show that the proposed method has better performance than Gardner method and the modified Gardner method.

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Timing recovery based on zero-crossing detection for multi-level PAM signals (영점교차검출에 의한 다중레벨 PAM 신호의 타이밍 복원)

  • 김정권;이용환
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.10
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    • pp.2246-2255
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    • 1997
  • Gardner proposed an algorithm for timing recovery of BPSK/QPSK signals based on zero-crossing detection technique. When Gardner's method is applied to multi-level PAM signals, it suffers from increased timing jitter due to self noise. To alleviate this problem, an improved algoritjm is proposed in this paper. The timing function is modified so that it zero point at the transition of PAM signals, that results in remarkable reduced timing jitter. The performance of the proposed algorithm is analyzed and compared to that of Garner's one. Finally, analytical results are verified by computer simulation.

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Synthesis and Optical Characteristics of PAM/HgS Nanocomposites

  • Qin, Dezhi;Yang, Guangrui;Zhang, Li;Du, Xian;Wang, Yabo
    • Bulletin of the Korean Chemical Society
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    • v.35 no.4
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    • pp.1077-1081
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    • 2014
  • Polyacrylamide (PAM) -HgS nanocomposites were successfully prepared in polyacrylamide (PAM) matrix. From TEM and XRD characterizations, the synthesized HgS nanocrystals were chain-like spherical in shape with a diameter of about 40-60 nm and high crystalline quality. The quantum-confined effect of HgS nanocrystals was confirmed by UV-vis diffuse reflection spectra. The optical properties of products were investigated by using photoluminescence (PL) spectra, which showed that HgS nanocrystals exhibited good optical properties with maximum emission peak at about 640 and 650 nm at different reaction temperatures. The interaction of HgS nanocrystals with PAM was studied through FT-IR spectroscopy and TG analysis, which suggested that $Hg^{2+}$ could interact with functional groups of PAM. The experimental results indicated that PAM not only induced nucleation, but also inhibited further growth of HgS crystals and play an important role in the formation of PAM/HgS nanocomposites. In addition, the possible mechanism of HgS nanoparticles growth in PAM solution was also discussed.

Compressibility and hydraulic conductivity of calcium bentonite treated with pH-responsive polymer

  • Choo, Hyunwook;Choi, Youngmin;Kim, Young-Uk;Lee, Woojin;Lee, Changho
    • Geomechanics and Engineering
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    • v.22 no.4
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    • pp.329-337
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    • 2020
  • Polyacrylamide (PAM) possesses high water absorption capacity and a unique pH-dependent behavior that confer large potential to enhance the engineering performance of clays. In this study, calcium bentonite was treated with a nonionic PAM. Flexible-wall permeability test and the consolidation test were performed at different pH values to evaluate the effects of PAM treatment on the hydraulic and consolidation properties. Test results demonstrate that index properties are affected by the adsorbed PAM on clay surface: a decrease in specific gravity, a decrease in net zeta potential, and an increase in liquid limit are observed due to the PAM treatment. At a given pH, the compressibility of the treated clay is greater than that of the untreated clay. However, the compression indices of untreated and treated clays can be expressed as a single function of the initial void ratio, regardless of pH. Hydraulic conductivity is reduced by PAM treatment about 5 times at both neutral and alkaline pH conditions under similar void ratios, because of the reduction in size of the water flow channel by PAM expansion. However, at acidic pH, the hydraulic conductivity of the treated clay is slightly higher than the untreated clay. This reflects that the treated bentonite with PAM can be beneficially used in barrier system for highly alkaline residues.

Poly(vinyl alcohol) Nanocomposite Films (II): Thermo-mechanical Properties and Morphology (폴리(비닐 알코올) 나노복합체 필름(II) : 열적-기계적 성질 및 모폴로지)

  • Ham, Shin-Kyun;Jung, Min-Hye;Chang, Jin-Hae
    • Polymer Korea
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    • v.30 no.6
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    • pp.545-549
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    • 2006
  • Blends of poly(acrylic acid- co-maleic acid) (PAM) with poly (vinyl alcohol) (PVA) were pre -pared in distilled water PVA/PAM/saponite (PVA/PAM/SPT) nanocomposite films were prepared with various clay contents by using the solution intercalation method. The variations of the dispersion, morphology, and thermo-mechanical properties of the nanocomposites with clay content in the range 0 to 9 wt% were examined. Up to 3 wt% clay loading, the clay particles were homogeneously dispersed in the PVA/PAM blends. However, some agglomerated structures form in the polymer matrix above a clay content of 7 wt%. The thermal stability of the hybrids was increased linearly with increasing the clay loading up to 9 wt%. The maximum strength and modulus were obtained at a clay content of 7 wt%. Thus, the addition of small amounts of clay to the PVA/PAM blends produced PVA/PAM nano-composites with improved the thermo-mechanical properties.

Performance of fly ash based polymer gels for water reduction in enhanced oil recovery: Gelation kinetics and dynamic rheological studies

  • Adewunmi, Ahmad Akanbi;Ismail, Suzylawati;Sultan, Abdullah Saad;Ahmad, Zulkifli
    • The Korean Journal of Chemical Engineering
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    • v.34 no.6
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    • pp.1638-1650
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    • 2017
  • The complexity of well and reservoir conditions demands frequent redesigning of water plugging polymer gels during enhanced oil recovery (EOR). In the present study, we developed coal fly ash (CFA) based gels from polyacrylamide (PAM) polymer and polyethyleneimine (PEI) crosslinker for water control in mature oil fields. The CFA acts as an inorganic additive to fine-tune gelation performance and rheological properties of PAM/PEI gel system. Hence, effects of various CFA (0.5 to 2 wt%), PAM (2 to 8.47 wt%) and PEI (0.3 to 1.04 wt%) concentrations on gelation kinetics and dynamic rheology of pure PAM/PEI gel and PAM/PEI-CFA composite gels were studied at a representative reservoir temperature of $90^{\circ}C$. Experimental results reveal that gelation time of pure PAM/PEI gel increases with increasing CFA addition. Further observation demonstrates that increasing PAM and PEI concentrations decreases the gelation times of PAM/PEI-CFA composite gels. Gelation time was found to be within 3-120 hours. Understanding the property of reaction order enables better prediction of gelation time. Dynamic rheological data show that viscoelastic moduli (G' and G'') of various PAM/PEI-CFA composite gels improved better as compared to the pure PAM/PEI gel across the strain-sweep and frequency-sweep tests. SEM analysis of selected samples at 72 hours and 720 hours of gelation activity consolidated gelation kinetics and dynamic rheological results. These polymer gels are excellent candidates for sealing water thief zones in oil and gas reservoirs.