• Title, Summary, Keyword: PPF

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Settlement Characteristics of Short-fiber Reinforced Soil under Dynamic Loading (동적하중에 의한 단섬유 보강토의 침하 특성)

  • Park, Young-Kon;Kim, Jung-Ki;Hwang, Seon-Keun;Shin, Min-Ho
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • pp.321-324
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    • 2002
  • To analyze the settlement characteristics of short-fiber reinforced soil(SFRS) under dynamic loading, a series of tests with loading condition of 5 Hz frequency and 500,000 cycles were performed. The materials used for tests are a soil of SM type and short-fibers with polypropylene and monofilament or fibrillated type. From the tests, average plastic settlement of SFRS at PPF38(0.3%), PPF38(0.5%), PPM60(0.2%) is low. Elastic settlement of SFRS is low at PPM60(0.2%) and is high at PPF60(0.5% ).

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Active Control of Multi-Mode Forced Vibration Using PZT (PZT를 이용한 다중 모드 강제 진동의 능동 제어)

  • 한상보;윤신일
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.407-412
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    • 1997
  • There has been a recent surge of research interest on the smart structure. This paper presents active vibration control scheme of multi-mode forced vibration using piezoceramic sensors/actuators. The control scheme adopted is the Positive Position Feedback control. Among various vibration control techniques, PPF control technique makes use of generalized displacement measurements to accomplish vibration suppression. Two independent controllers are implemented to control the first and the second modes of the beam under external excitation. Experimental results for various damping ratio and feedback gains of the PPF controllers are compared with respect to the control efficiency. The results indicate that steady state vibration under wideband excitation can be controlled effectively when multiple sets of PZT sensors/actuators were used with PPF control technique.

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The Electrical Characteristics of MPPF for Capacitor Applications under AC condition (커패시터용 MPPF의 교류전압 인가시 전기적 특성)

  • 정종욱;곽희로;박중신
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • pp.155-159
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    • 2000
  • This paper describes the self healing characteristics of metalized polypropylene film(MPPF) under ac condition. PDs were generally observed at relatively low voltage, and the PDIVs were differently varied depending on the number of pre-self healing due to void defects. Several pre-self healing events took place at lower voltage than the critical breakdown voltage of PPF. Self healing mainly occurred at pin tips, wrinkle sides, and cross points of wrinkles. The applied voltage at self healing was increased with PPF thickness. The burn out area at self healing was also increased with the applied voltage and PPF thickness. The peak currents in a grounding conductor at self healing was also increased with the applied voltage.

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The development of biodegradable resin for scaffold fabrication using micro-stereolithography and curing characteristics analysis of the resin (마이크로 광 조형기술을 이용한 인공지지체의 제작을 위한 생분해성 수지의 개발 및 경화 특성 파악)

  • Lee J.W.;Cho D.W.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.147-148
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    • 2006
  • A research on scaffold fabrication has been progressed in many research groups. However, the mechanical properties of existing biodegradable materials are still not satisfactory. But, PPF (poly (propylene fumarate)) has a good mechanical property in comparison to other biodegradable materials. Nevertheless, the viscosity of the synthesized PPF is too high to fabricate structures using micro-stereolithography. Therefore, the viscosity of the resin was made low by adding the diethyl fumarate and this material could be used in micro-stereolithography apparatus. Then, a photoinitiator was added for photo crosslinking of the DEF/PPF resin. 2.5D and 3D scaffolds were fabricated our system and curing characteristics of the resin were analyzed through the experiment.

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Vibration Suppression of Beam Using Magnet and Coil (자석과 코일을 이용한 빔의 진동 억제)

  • Cheng, Tai-Hong;Jung, Jung-Hwan;Oh, Il-Kwon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.727-730
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    • 2007
  • Coil inductor has been used widely as an electromagnet, because of the high magnetic filed resulting from the voltage applied to the coil. In this study the coils were used in vibration suppression as an actuator. The control system consists of a coil attached in aluminum beam and a permanent magnet set at its bottom. This actuation method is easy to be incorporated into the system and allows significant forces to be applied without contacting with the structure. Three types of coils (cylindrical type, square type, Circular sheet type) were employed in vibration suppression of cantilever beam. The positive position feedback (PPF) controller was applied to the magnet-coil actuator to suppress the first mode of vibration. Experimental results showed that the cylindrical type and square type coil made good vibration suppression efficiency under PPF controller than their eddy current damper. However, there was minimal difference for the circular sheet type coil if compared with its eddy current damper.

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Improvement of Runner Plant Production by Increasing Photosynthetic Photon Flux during Strawberry Transplant Propagation in a Closed Transplant Production System (폐쇄형 육묘 시스템에서 딸기의 러너플랜트 생산 증진에 적합한 광합성유효광량자속)

  • Kim, Sung-Kyeom;Jeong, Mi-Seon;Park, Seon-Woo;Kim, Moo-Jung;Na, Hae-Young;Chun, Chang-Hoo
    • Horticultural Science & Technology
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    • v.28 no.4
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    • pp.535-539
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    • 2010
  • The formation and elongation of runners, growth of runner plants, and transplant propagation rates of 'Maehyang' strawberry were investigated at various photosynthetic photon flux (PPF) levels. Strawberry plants having $3.1{\pm}0.4$ leaves and $7.0{\pm}1.1mm$ of crown diameter were used as propagules and were cultured for 35 days in 9 transplant production modules using fluorescent lamps as artificial lighting sources. Applied PPF levels were $137.4{\pm}2.1$, $217.0{\pm}1.0$, and $274.7{\pm}8.4{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ as measured on the surfaces of empty shelves. The numbers of runners and runner plants per propagule were the greatest at $280{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPF. The runner plant propagation rate was 0.27 plant/day/propagule at $280{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, which was significantly greater than that of conventional propagation methods. Results indicate that high PPF levels promotes the formation of runners and runner plants of strawberry and that the rapid propagation method with high PPF levels can be feasible for production of vigorous transplants in a closed transplant production system.

The Effects PPF Fiber on Concrete Properties (PPF 섬유가 콘크리트의 물성에 미치는 영향)

  • 한만엽
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.150-155
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    • 1993
  • The use of polypropylene fibers in concrete has been widely advertised by the fiber manufacturers. However, the behavior of concrete containing plastic fibers has not been fully understood. The effects of fiber on concrete have been forcused on shrinkage crack control mainly from field observation, and the mechanism and the side effect of fiber such as workability reduction have been neglicted. In this paper, the effect of fiber on workability and shrinkage properties have been studied. The addition of fiber significantly reduce workability and requires additional water to maintain the workability, which causes adversal effects on concrete properties.

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A study on DR image restoration using dual sensor (이중센서를 이용한 DR 영상 개선에 관한 연구)

  • 백승권;이태수;민병구
    • 제어로봇시스템학회:학술대회논문집
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    • pp.725-728
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    • 1988
  • Image restoration technique using dual sensor is presented in this paper. Digital Radiography image (1024xlO24) is obtained by conventional resolution sensor. We also obtain local DR image data by high resolution sensor. Two dimensional maximum entropy power spectrum estimation (2-D ME PSE) is applied to low resolution image and high resolution image for the purpose of the power spectrum estimation of each image. A class of linear algebraic restoration filter, parametric projection filter (PPF), is derived from the power spectrums of each image. It is shown that the noise energy may be considerably reduced through the PPF.

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Progression of Surface Treatment Technology at Leadframe (리드프레임 표면처리 기술의 진화)

  • Park, Se-Cheol
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • pp.135-135
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    • 2012
  • 세계 환경유해물질 규제에 대응하여 반도체 substrate의 Pb-free solution의 일환으로 등장한 PPF (Pre-Plated Frame)는 패키지공정 조립성은 물론, 자동차 반도체와 같은 고 신뢰성 및 low cost 요구를 만족하기 위해 초박막 고품질의 도금층과 Sub-micro scale의 rough treatment 와 같은 미세 표면제어 기술, 그리고 Au wire로부터 Cu wire 로의 전환에 대응하는 최적화된 도금층 구조로 발전하고 있다. 이러한 기술적인 진화를 거듭해온 이 기술은 다양한 반도체 substrate에 광범위하게 사용될 수 있기 때문에 향후 PPF기술의 활용저변은 더욱 확대될 전망이다.

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Expression and Biochemical Characterization of the Bacillus thuringiensis Cry4B ${\alpha}1$-${\alpha}5$ Pore-forming Fragment

  • Puntheeranurak, Theeraporn;Leetacheewa, Somphob;Katzenmeier, Gerd;Krittanai, Chartchai;Panyim, Sakol;Angsuthanasombat, Chanan
    • BMB Reports
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    • v.34 no.4
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    • pp.293-298
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    • 2001
  • Tryptic activation of the 130-kDa Bacillus thuringiensis Cry4B $\delta$-endotoxin produced protease-resistant products of ca. 47 kDa and ca. 21 kDa. The 21-kDa fragment was identified as the N-terminal five-helix bundle (${\alpha}1-{\alpha}5$,) which is a potential candidate for membrane insertion and pore formation. In this study, we constructed the recombinant clone over-expressing this putative pore-forming (PPF) fragment as inclusion bodies in Escherichia coli. The partially purified inclusions were composed of a 23-kDa protein, which cross-reacted with Cry4B antibodies, and whose N-terminus was identical to that of the 130-kDa protein. Dissimilar to protoxin inclusions, the PPF inclusions were only soluble when the carbonate buffer, pH 9.0, was supplemented with 6 M urea. After renaturation via a stepwise dialysis, the refolded PPF protein appeared to exist as an oligomer and was structurally stable upon trypsin treatment. Unlike the 130kDa protoxin, the refolded protein was able to release entrapped glucose from liposomes, and showed comparable activity to the full-length activated toxin, although it lacks larvicidal activity These results, therefore, support the notion that the PPF fragment that consists of ${\alpha}1-{\alpha}5$ of the activated Cry4B toxin is involved in membrane pore-formation.

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