• Title/Summary/Keyword: PVD

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Numerical Analyses on Consolidation Promotion Effect of Soft Clay Ground by Prefabricated Vertical Drain (PVD에 의한 연약점토지반의 압밀촉진효과에 대한 수치해석)

  • You, Seung-Kyong
    • Journal of the Korean Geosynthetics Society
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    • v.8 no.1
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    • pp.19-24
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    • 2009
  • In this paper, a series of numerical analyses on soft clay ground improved by PVD were carried out, in order to investigate the consolidation promotion effect considering PVD width and surcharge pressure. In the numerical analyses, an elasto-viscoplastic three-dimensional consolidation finite element method was applied, in which the applicability of numerical analyses could be confirmed comparing with consolidation behavior simulated at the laboratory. And, through the results of the numerical analyses, consolidation behaviors of soft clay ground with elapsed time was elucidated, together with the effects of PVD width and surcharge pressure.

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Study on the PVdF Nanofibers and Graphene Oxide Hybrid Membrane (PVdF 나노섬유와 Graphene Oxide 하이브리드막에 관한 연구)

  • Jung, Hyemin;Chen, Weidong;Yang, Woo Seok;Byun, Hongsik
    • Membrane Journal
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    • v.23 no.3
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    • pp.204-210
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    • 2013
  • Recently, many applications with grapheneoxide (GO) have been reported. But GO membrane for water treatment has not been developed. In this study we prepared polyvinylidene difluoride (PVdF) nanofiber/GO hybrid membrane (FG) for the microfiltration application. The PVdF substrate membrane was prepared by using the electrospinning method with a solution of PVdF in N,N-dimethylacetamide (DMAc) and acetone. GO sheets used in this study were prepared by modified Hummer's method. The PVdF/GO hybrid membrane was finally prepared by spraying the GO solution dispersed in ethanol on the PVdF nanofiber. The successfully prepared FG was thoroughly examined by SEM, Raman, contact angle, porometer and UTM, and water-flux was measured with designed cell (Dead-End Cell). From the contact angle results, it was found that the surface of FG membrane was reformed by hydrophilic property and the water permeability was increased about 2.5 times than that of the nascent PVdF membrane, indicating the possible alternative of the commercial MF membrane.

Property Studies of PAN/PVdF Composite Nanofiber Manufactured from Electrospinning (전기방사법으로 제조된 PAN/PVdF 복합나노섬유의 특성연구)

  • Yun, Jung-Hyun;Choi, Dong-You
    • 전자공학회논문지 IE
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    • v.46 no.3
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    • pp.6-11
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    • 2009
  • In this paper, manufactured composite nanofiber by electrospinning that make spinning solvent according to weight of PAN/PVdF. PVdF content of composite nanofiber decreases, diameter of fiber decreased. Result that measure contact angle to confirm hydrophile property of PAN/PVdF composite nanofiber, PVdF content increases, could confirm that contact angle with water increases. After leave filter measurement sample for 25 hours in temperature of $40^{\circ}C$, humidity of 85%, result PAN/PVdF composite nanofiber that estimate efficiency could confirm that display performance of HEPA more than 99.95% and ULPA more than 99.999%. And fiber diameter is small, could confirm that filter performance increases. Tensile strength of bulk of PAN/PVdF composite nanofiber was 5-8MPa, expansion 100-300%. And strength and expansion could know that increase according as PVdF's content increases. Tensile strength was 3-8MPa degree after annealing PAN/PVdF composite nanofiber during 2 hours in 120t. Tensile strength was no change almost by annealing, and expansion could know that decrease.

LOCALLY PSEUDO-VALUATION DOMAINS OF THE FORM D[X]Nv

  • Chang, Gyu-Whan
    • Journal of the Korean Mathematical Society
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    • v.45 no.5
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    • pp.1405-1416
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    • 2008
  • Let D be an integral domain, X an indeterminate over D, $N_v = \{f{\in}D[X]|(A_f)_v=D\}.$. Among other things, we introduce the concept of t-locally PVDs and prove that $D[X]N_v$ is a locally PVD if and only if D is a t-locally PVD and a UMT-domain, if and only if D[X] is a t-locally PVD, if and only if each overring of $D[X]N_v$ is a locally PVD.

Ceramic Coating by Electron Beam PVD for Nanos-Tructure Control (나노구조 제어를 위한 EB-PVD법에 의반 세라믹스 코팅)

  • Matsbara, Hideaki
    • Ceramist
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    • v.9 no.6
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    • pp.24-29
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    • 2006
  • Electron beam physical vapor deposition (EB-PVD) process has currently been applied to thermal barrier coatings (TBCs) for aircraft engines. Due to unique columnar structure, EB-PVD TBCs have advantages in resistances to thermal shock and thermal cycle for their applications, compared to films prepared by plasma spray By the EB-PVD equipment, we successfully obtained yttria-stabilized zirconia (YSZ) layer which has columnar and feather like structure including a large amount of nano size pores and gaps. The EB-PVD technique has been developed for coating functional perovskite type oxides such as (La, Sr)MnO3. Electrode properties have been improved by interface and structural control.

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Impact of PVD Coating Technology on HSS Tool (HSS공구와 PVD 코팅기술의 영향)

    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.899-904
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    • 2001
  • The impact of PVD coatings can be summed up in practical terms: this technology historically complements the best designed tool substrates to enhance cutting performance. PVD coatings are now incorporated in 25% of all HSS tools. The functionality is to extend the machining speed range, improve wear resistance at the cutting edge, and reduce friction at chip/tool contact areas to allow easier chip evacuation. These translate to a larger safe zone, as discussed in the failure mode diagram, for better productivity and higher reliability in machining operations of the customer. PVD coatings therefore represent an enabling technology that extends the application range of cutting tools in response to modern industrial needs. PVD coatings prolong the product life cycle of HSS tools and help this "mature" material to hold its territory against the advent of the newer hardmetal and ceramic tool materials. There is a lot of competitive life left particularly in PVD coated HSS endmills, drills, threading/tapping tools. PM HSS technology further increases the possibilities.ibilities.

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Convenient Preparation of Ion-Exchange PVdF Membranes by a Radiation-Induced Graft Polymerization for a Battery Separator (배터리 분리막을 위한 이온교환형 PVdF 맴브레인의 방사선 그래프트법에 의한 간편한 제조법)

  • Kim, Sang-Kyum;Ryu, Jung-Ho;Kwen, Hai-Doo;Chang, Choo-Hwan;Cho, Seong-Ho
    • Polymer(Korea)
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    • v.34 no.2
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    • pp.126-132
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    • 2010
  • A cation-exchange nanofiber poly(vinylidene fluoride) (PVdF) membrane was prepared by a radiation-induced graft polymerization (RIGP) of sodium styrene sulfonate (NaSS) in the presence of the polymerizable access agents in methanol solution. The used polymerizable access agents include styrene, acrylic acid, and vinyl pyrrolidone. The anion-exchange nanofiber PVdF membrane was also prepared by RIGP of glycidyl methacrylate (GMA) and its subsequent chemical modification. The successful preparations of cation- and anion-exchange PVdF membranes were confirmed via SEM, XPS and thermal analysis. The content of the grafting yield, ion-exchange group, and water uptake was in the range of 30.0~32.3%, 2.81~3.01 mmol/g and 66.6~147%, respectively. The proton conductivity at 20$^{\circ}C$ was in the range of 0.020~0.053 S/cm. From the result, the prepared ionexchange PVdF membrane can be used as a separator in battery cells.

Tendency of PVD coating technology on Metal cutting tools (금속 절삭공구에 대한 PVD 코팅기술의 동향)

  • Kim, Jong-Seong
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.8
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    • pp.11-17
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    • 2001
  • Industrial use of physical vapor deposition(PVD) has been widely expanded during last two decades, and in the mean time plasma assistance in PVD has become an essential tool in preparing compound films with dense microstructure. The principles of electron beam-based plating, balanced and unbalanced magnetron sputtering and cathodic arc deposition. consisting three basic configuration of plasma assisted PVD(PAPVD)process, were reviewed. Recent technical development in PVD coating process were discussed. This paper tries to show tendency for developing new coating film on cutting tools.

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High Speed Zinc Coating by EML-PVD Process (EML-PVD를 이용한 고속 Zn 코팅)

  • Jeong, U-Seong;Nam, Gyeong-Hun;Eom, Mun-Jong;Kim, Tae-Yeop
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2012.05a
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    • pp.277-277
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    • 2012
  • New concept of coating process, which is called Electro Magnetic Levitation-Physical Vapour deposition (EML-PVD) was developed and investigated. Zinc coating was performed and succeeded for the first time on the steel strip (Cold-rolled Steel) in a continuos pilot line using the EML-PVD process which is specialized in the high deposition rate and high vapor yield. EML-PVD will be expected to be the next generation coating technology to be applied to the steel industry.

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Preparation of PVdF/GO Composite Nanofibrous Flat Membrane and its Permeation Characteristics in Activated Sludge (PVdF/GO 복합 나노섬유 평막의 제조 및 활성슬러지 내 투과특성)

  • Won, In Hye;Jang, Wongi;Chung, Kun Yong;Byun, Hongsik
    • Membrane Journal
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    • v.25 no.1
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    • pp.67-74
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    • 2015
  • In this study the nanofiber was prepared by electrospinning method with polyvinylidene fluoride (PVdF) and a completely dispersed solution of graphene oxide (GO) in the mixed solvent of dimethylformamide (DMF) and acetone. The $0.4{\mu}m$ pore size microfiltration flat membrane was made by increasing layers of the PVdF/GO composite nanofiber. Also, transmembrane pressure (TMP) was measured in order to evaluate fouling of the PVdF/GO composite membrane which was introduced GO reducing biological fouling with the intrinsic antibacterial characteristics. The permeate experiments were carried out simultaneously for the PVdF/GO and commercialized CPVC (chlorinated polyvinyl chloride) flat membranes with $0.01m^2$ effective area in the activated sludge solution of MLSS 4,500 mg/L. TMP of PVdF/GO membrane decreased up to 79% lower than that of CPVC for $10L/m^2{\cdot}h$ permeate flux without air supply. Also, for the case of run/stop operational mode, TMP of PVdF/GO membrane decreased up to 69% lower than that of CPVC for $10L/m^2{\cdot}h$.