• 제목/요약/키워드: Opc

검색결과 969건 처리시간 0.028초

Hydration Property of Electric Arc Furnace Reduction Slag (전기로(電氣爐) 환원(還元) 슬래그의 수화반응(水和反應) 특성(特性) 연구(硏究))

  • An, Yong-Jun;Han, In-Kyu;Choi, Jae-Seok;Bae, Kwang-Hyun;Kim, Hyung-Seok
    • Resources Recycling
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    • 제19권6호
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    • pp.93-101
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    • 2010
  • In this study, we have studied hydration properties and compressive strength of the electric arc furnace reduction slag as a cement admixture. The reduction slag is mainly consisted of 17.1% of f-CaO and rapid curing clinker minerals, 37.1% of $C_{11}A_7CaF_2$, and 21.0% of $C_3A$. When the substitution rate of the slag on OPC was 30%, the initial setting time and final setting time has been shortened from 305 min. and 425 min. to 10min. and 30min. When the substitution rate of the slag on OPC was 7%, the compressive strength of mixed cement mortars has been increased than that of OPC during all period. When the substitution rate of the slag on OPC was over 20%, the compressive strength of mortars has been reduced than that of OPC at initial and final compressive strength. As a result of hydration properties of reduction slag, $C_{11}A_7CaF_2$ transfer to $C_3AH_6$ but as the substitution rate of slag on OPC increases, increased f-CaO and the metastable hydrates $C_4AH_{13}$ increased. Therefore, we should control the substitution rate of the slag on OPC was under 7% in order to use EAF reduction slag as a cement admixture.

Sulfate and Freeze-thaw Resistance Characteristic of Multi-component Cement Concrete Considering Marine Environment (해양환경을 고려한 다성분계 시멘트 콘크리트의 황산염 및 동결융해 저항 특성)

  • Kim, Myung-Sik;Beak, Dong-Il;Kang, Jun-Ho
    • Journal of Ocean Engineering and Technology
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    • 제26권3호
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    • pp.26-32
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    • 2012
  • Recently, concrete using multicomponent blended cement has been required to increase the freeze-thaw and sulfate resistances of concrete structures exposed to a marine environment. Thus, the purpose of this study was to propose the use of concrete containing multicomponent blended cement as one of the alternatives for concrete structures exposed to a marine environment. For this purpose, batches of concrete containing ordinary portland cement (OPC), binary blended cement (OPC-G, G: ground granulated blast slag), ternary blended cement (OPC-GF, F: fly ash), and quaternary blended cement (OPC-GFM, M: mata-kaolin) were made using a water-binder ratio of 50%. Then, the durability levels, including thesulfate and freeze-thaw resistances, were estimated for concrete samples containing OPC, OPC-G, OPC-GF, and OPC-GFM. It was observed from the tests that the durability levels of the concrete samples containing OPC-G and OPC-GF were found to be much better than that of the concrete containing OPC. The optimum mixing proportions were a40% replacement ratio of ground granulated blast slag for the binary blended cement and a30% replacement ratio of ground granulated blast slag and 10% fly ash for the ternary blended cement.

Performance Improvement of WDM Channels using Inline Dispersion Management in Transmission Link with OPC Placed at Various Position (다양한 위치에 존재하는 OPC를 갖는 전송 링크에서 Inline 분산 제어를 이용한 WDM 채널의 성능 개선)

  • Lee, Seong-Real
    • Journal of Advanced Navigation Technology
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    • 제14권5호
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    • pp.668-676
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    • 2010
  • Optimal net residual dispersions (NRDs) of inline dispersion management (DM) for compensating the signal distortion of $24{\times}40$ Gbps WDM channels in optical transmission links, in which optical phase conjugator (OPC) is placed from 250 km to 750 km by spacing 50 km in 1,000 km total transmission length of single mode fiber (SMF), are induced as a function of various ope positions. And, performance improvement of WDM channels in transmission links with the induced optimal NRD is investigated by comparing with that in transmission links with NRD = 0 ps/nm. It is confirmed that optimal NRDs are decided by displacement of OPC from mid-way of total transmission length, i.e. 500 km, and the determinating and applying of optimal NRD in case of ope displacement into transmitters is more stable and effective than that in case of ope displacement into receivers from 500 km. Also, it is shown that eye opening penalties (EOPs) of WDM channels in transmission links with optimal NRD are improved by 1.5 dB to 3 dB, which are related with OPC position, from that obtained in transmission links with fixed NRD of 0 ps/nm.

Compensation Characteristics Dependence on the Position of Optical Phase Conjugator in 320 Gbps WDM System

  • Lee Seong-Real;Yim Hwang-Bin
    • Journal of electromagnetic engineering and science
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    • 제4권4호
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    • pp.162-167
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    • 2004
  • In this paper, optimal position of optical phase conjugator(OPC) for best compensating distorted WDM channels due to both chromatic dispersion and self phase modulation(SPM) is numerically investigated, and the compensation characteristics of overall WDM channels at this position is investigated, comparing with that in case of OPC placed at mid-way of total transmission length. It is confirmed that the compensation extents in WDM system with OPC is more improved by the shifting OPC position from the mid-way of total transmission length. And, we confirmed that the optimal position of OPC must be selected to the position decreasing not only eye opening penalty(EOP) of overall WDM channels but also EOP deviation between WDM channels, and this OPC position should be altered as various system parameters such as modulation format, and fiber dispersion, etc. Using proposed configuration, it is possible to remove all in-line dispersion compensator, reducing span losses and system costs.

A Development of Primary Charging Roller for OPC Drum (OPC Drum의 저압 대전체 개발)

  • Cho, Hyun-Seob
    • Journal of the Korea Academia-Industrial cooperation Society
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    • 제10권2호
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    • pp.243-247
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    • 2009
  • Primary charging roller is rotated with contacting surface of OPC drum and take charge OPC drum. Owing to this reason, primary charging roller is made by elasticity substance with electric conduction. Properties of charging and image is changed by class of coating, method of coating and environment. This study developed coating material and coating method to make print image of good quality.

Analgesic Effect of Grape Seed Proanthocyanidin Extract in Fibromyalgia Animal Model (섬유근통 동물 모델에서 포도씨 추출 proanthocyanidin의 진통 효과)

  • Mun, Hyun-Il;Kim, Seong-Ho;Jang, Tae-Jung;Moon, Il-Soo
    • Journal of Life Science
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    • 제20권4호
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    • pp.496-502
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    • 2010
  • The acidic saline animal model of pain has been suggested to mimic fibromyalgia (FM). Oligomeric proanthocyanidin complexes (OPC) from grape seeds are known to act as an antioxidant. We studied the effects of OPC on the pain threshold in the acidic saline animal model of pain. The left gastrocnemius muscle was injected with $100\;{\mu}l$ of saline at pH 4.0 under brief isoflurane anesthesia on days 0 and 5. Control rats (n=5) received identical injections of physiological saline (pH 7.2) on the same schedule. Rats (n=10) with acidic saline injection were separated into two study subgroups. After measurement of pre-drug pain thresholds, rats were injected intraperitoneally with either saline or OPC 300 mg/kg. Paw withdrawal thresholds to pressure were again measured 60 min after intraperitoneal injection. Nociceptive thresholds were measured with a Dynamic Plantar Aesthesiometer by applying an increasing pressure to right or left hind paw until the rat withdrew the paw. Compared to baseline (day 0), acid injections produced mechanical hyper-responsiveness on day 7 (pre-drug) in these rats [p<0.05]. A potent antihyperalgesic effect was observed when rats were injected intraperitoneally with OPC 300 mg/kg [injected paw, p=0.001; contralateral paw, p=0.002]. OPC treatment decreased the expression of acid sensing ion channel 3 in the brain motor cortex area on immunohistochemical staining when OPC 300 mg/kg was administered intraperitoneally in the animal model of FM pain [p<0.05]. Further research is required to determine the efficacy of OPC treatments in FM pain in humans.

The Effects of Na2CO3 on Early Strength of High Volume Slag Cement (대량치환 슬래그 시멘트의 초기강도에 미치는 Na2CO3의 영향)

  • Kim, Tae-Wan;Hahm, Hyung-Gil
    • Journal of the Korea Concrete Institute
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    • 제28권3호
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    • pp.349-356
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    • 2016
  • This report presents the results of an investigation on the early strength development of pastes high volume slag cement (HVSC) activated with different concentration of sodium carbonate ($Na_2CO_3$). The ordinary Portland cement (OPC) was replaced by ground granulated blast furnace slag (GGBFS) from 50% to 90% by mass, the dry powders were blended before the paste mixing. The $Na_2CO_3$ was added at 0, 2, 4, 6, 8 and 10% by total binder (OPC+GGBFS) weight. A constant water-to-binder ratio (w/b)=0.45 was used for all mixtures. The research carried out the compressive strength, ultrasonic pulse velocity (UPV), water absorption and X-ray diffraction (XRD) analysis at early ages(1 and 3 days). The incase of mixtures, V5 (50% OPC + 50% GGBFS), V6 (40% OPC + 60% GGBFS) and V7 (30% OPC + 70% GGBFS) specimens with 6% $Na_2CO_3$, V8 (20% OPC + 80% GGBFS) and V9 (10% OPC + 90% GGBFS) specimens with 10% $Na_2CO_3$ showed the maximum strength development. The results of UPV and water absorption showed a similar tendency to the strength properties. The XRD analysis of specimens indicated that the hydration products formed in samples were CSH and calcite phases.

Q-factor Improvements of WDM Signals using Optical Transmission Link with Dispersion Management and OPC (분산 제어와 OPC를 갖는 광전송 링크를 이용한 WDM 신호의 Q-factor 개선)

  • Lee, Seong-Real
    • Journal of Advanced Navigation Technology
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    • 제13권1호
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    • pp.27-33
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    • 2009
  • New optical transmission link techniques improving performance of WDM channels, each channel have bit rate of 40 Gbps, are proposed. The proposed optical link configuration consist of optical phase conjugator (OPC) placed at middle of total transmission length, and dispersion management (DM) as a role of compensating dispersion cumulated in transmission line. It is confirmed that Q-factor of total channels are improved by combining OPC and DM in optical transmission link as a result of following fact; DM not only mitigate the cumulated dispersion in total transmission line but also help OPC to compensate optical nonlinearities. And, it is confirmed that the improvement of Q-factor of overall WDM channels depends on net residual dispersion (NRD) of optical link.

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An Experimental Study on Corrosion Resistance of Cracked Concrete (균열 콘크리트에서의 부식저항성에 관한 실험적 연구)

  • Song, Ha-Won;Lee, Chang-Hong;Ann, Ki-Yong;Lee, Kewn-Chu
    • Proceedings of the Korea Concrete Institute Conference
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    • 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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    • pp.517-520
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    • 2008
  • In this study, corrosion resistance of steel in cracked-reinforced concrete was performed according to experimental method. Mixed design is OPC, 30% PFA, 60% GGBS and 10% SF, respectively. Moreover, corrosion resistance test was measured using ultra testing machine for 0.3mm crack induction. The corrosion resistance of blended concrete shows the results following OPC > 10%SF > 30% PFA > 60% GGBS after 60days curing. In case of mass loss test, embedded reinforcement in OPC concrete surveyed the minimum corrosion and appeared better corrosion resistance than blended concrete. As a result, corrosion resistance of sound concrete is higher than cracked concrete. Moreover, corrosion resistance of binary concrete is lower than OPC.

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The Analysis of Fundamental Property for Developing High Performance Concrete of Ternary System (3성분계 고성능 콘크리트 개발을 위한 기초 특성 분석)

  • Park, Byung-Kwan;Choi, Sung-Yong;Kim, Soo-Yung;Kim, Bok-Kyu;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korea Concrete Institute Conference
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    • 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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    • pp.805-808
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    • 2008
  • This study analyzed the basic characteristics of concretes to develop 3 ingredients high performance concrete that displaced BS and FA, and the results are as follows. As part of fresh concrete characteristics, the flow was shown more increase than OPC with increase in admixture material displacement rate, and air amount tended to decrease with increase in admixture displacement rate. As hardened concrete characteristics, compressive strength decreased below OPC at early age with increase in BS and FA displacement rate, however at age 28 days, it was similar to OPC or increased above that. Particularly, at B30F15 with age 28 days, its compressive strength was about 15% higher than OPC

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