• Title/Summary/Keyword: loss of particles

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Fluidity Changes of Cement Paste added Superplasticizer and Inorganic Fine Powders for Cement Admixture (고유동화제와 시멘트 혼화용 무기미분체가 첨가된 시멘트 페이스트의 유동성 변화)

  • 김도수;정흥호;박병배;노재성
    • Journal of the Korean Ceramic Society
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    • v.37 no.8
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    • pp.751-759
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    • 2000
  • Effects of the dosage change, from 0 to 2.0 wt% based on cement weight, of naphthalenic (NSF) and polycarboxylic(NT-2) superplasticizers, on the fluidity of cement paste substituted by 10 wt% II-anhydrite and fly ash respectively as well as II-anhydrite and fly ash itself were investigated. Dispersion properties between particles in suspension were investigated by zeta potential test. Initial fluidity and slump loss in the paste system were observed through mini-slump and apparent viscosity changes with elapsed time. Zeta potential on the particle surface was a tendency to increase according to increasing of NSF dosage. Especially, zeta potential of fly ash has the highest value among all particles equivalent to NSF dosage. In the fluidity of cement paste substituted by inorganic particles, the specimen with substitution of 10 wt% II-anhydrite and fly ash for cement was more effective than cement itself to improve initial fluidity and retain stable fluidity of cement paste. In addition, effect of NT-2 and NSF to improve the fluidity of cement paste, addition of 1.0 wt% NT-2 was more effective than 1.5wt% NSF.

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The Preparation of Alumina Particles Wrapped in Few-layer Graphene Sheets and Their Application to Dye-sensitized Solar Cells

  • Ahn, Kwang-Soon;Seo, Sang-Won;Park, Jeong-Hyun;Min, Bong-Ki;Jung, Woo-Sik
    • Bulletin of the Korean Chemical Society
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    • v.32 no.5
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    • pp.1579-1582
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    • 2011
  • Alumina particles wrapped in few-layer graphene sheets were prepared by calcining aluminum nitride powders under a mixed gas flow of carbon monoxide and argon. The graphene sheets were characterized by powder X-ray diffraction (XRD), Raman spectroscopy, electron energy loss spectroscopy, and high-resolution transmission electron microscopy. The few-layer graphene sheets, which wrapped around the alumina particles, did not exhibit any diffraction peaks in the XRD patterns but did show three characteristic bands (D, G, and 2D bands) in the Raman spectra. The dye-sensitized solar cell (DSSC) with the alumina particles wrapped in few-layer graphene sheets exhibited significantly improved overall energy-conversion efficiency, compared to conventional DSSC, due to longer electron lifetime.

고진공에서 이온 카운터를 사용한 실시간 입자 모니터링 시스템의 개발

  • An Gang-Ho;Kim Yong-Min;Yun Jin-Uk;Gwon Yong-Taek
    • Proceedings of the Korean Society Of Semiconductor Equipment Technology
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    • 2006.05a
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    • pp.255-258
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    • 2006
  • In this paper, the new method which is monitoring quantity of particles using by ion-counter has been developed. ISPM system is composed by Gerdien type ion-counter (house-made), DC power supply and electrometer. Ion-counter applied positive voltage could detect only positive charged particles. Therefore charged particles to Boltzmann equilibrium distribution or to some identified charge distribution can be detected by ion-counter. Ion-counter could install on the exhaust line of process equipment since pressure loss is structurally low. ISPM system has been certified by comparison with the result of SMPS (Scanning Mobility Particle Sizer) system. The relation coefficiency is above 0.98 about $20{\sim}300nm$ particles with identified charge distribution under $0.1{\sim}10.0$ Torr.

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Heat Transfer Characteristics and Pressure Drop of a Fluidized Bed Heat Exchanger without Baffle Plate

  • Jun, Yong-Du;Lee, Kum-Bae
    • International Journal of Air-Conditioning and Refrigeration
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    • v.11 no.1
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    • pp.24-31
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    • 2003
  • A new fluidized bed heat exchanger for exhaust gas heat recovery is do-veloped. Compared to the existing ones, the present heat exchanger system is featured by the particle fluidization method which does not depend on conventionally used baffle plate with holes and by the multiple downcomer tubes to extract heat energy from hot particles during the time particles moves down to be fed again to the hot gas line. Particles are introduced to the main hot gas stream alongside the pipe circumference. The heat exchanger performance and pressure drop are evaluated through experiments for the present gas-to-water heat exchanger system.

Effect of Impact Angle on the Etching of Glass by Powder Blasting (Powder Blasting 을 이용한 유리의 표면부식시 분사각도의 영향)

  • 김광현;박경호;박동삼
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.10a
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    • pp.349-354
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    • 2001
  • In this study, we investigated the effect of the impacting ang1e of particles, the scanning times and the stand-off distance on the surface roughness and the weight-loss rate of samples with no mask, and the wall profile and overetching of samples with different mask pattern in powder blasting of soda-lime glass. The varying parameters were the different impact angles between 50$^{\circ}$ and 90$^{\circ}$, scanning times of nozz1e up to 40 and the stand-off distances 70mm and 100mm. The widths of mask pattern were 0.2mm, 0.5mm and 1mm. The powder was alumina sharp particles, WA#600. The mass flow rate of powder during the erosion test was fixed constant at 175g/min and the blasting pressure of powder at 0.2MPa

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Erosion Damage of Ultrasonic Vibrator Tip in Marine Sludge Oil Environment - study on depth of transducer disc - (선박 슬러지유 환경에서의 초음파 진동자 선단의 침식손상(2) - 침지깊이 변화에 따른 고찰 -)

  • 한원희;하만식;이진열
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.7 no.3
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    • pp.75-84
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    • 2001
  • Ultrasonic vibrator is an equipment which atomizes and homogenizes the oils by breaking the oil particles with ultrasonic vibration cavity, and possibly improves the properties. There are various parameters on the effect of ultrasonic irradiation. Especially, this study intended to investigate the matrix structure of sludge oils and the erosion damages for horn disc SS41 according to the variation of the oil temperature and the immersing depth of horn disc. Sludge oils were irradiated with ultrasonic vibration and then observed the aspects of the change of oil particles. From these, the recycling feasibility of sludge oil for useable oil to be burnt was determined. The erosion damages for horn disc SS41 were examined with weight loss, weight loss rate and the irradiation time to max. erosion rate. These data will be useful to the development of ultrasonic breaking systems to recycle sludge oil and to consider a countermeasure for the prevention of erosion damages.

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The Firing of Slag Containing Batch (광재 조합물 소성에 관한 연구)

  • 박기형;송한식;천성순;김종희
    • Journal of the Korean Ceramic Society
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    • v.15 no.4
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    • pp.185-192
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    • 1978
  • The effects of slag prticle size, $Na_2SO_4$ addition and sulphide in slag to the foam formation was investigated. This investigation showed that the slag particle size and the amount of $Na_2O$ had produced effects on the size of the foam, foam distribution and firing temperatures. In addition to that the amount of sulphide loss during the firing was controlling factor for the foam formation. The smaller slag particles and higher firing temperatures increased the loss of sulphide in the slag. The addition of $Na_2SO_4$ in the slag batch was likely to inhibit the foam formation. The larger slag particles resutled in the larger foam size and tended to be increasing the batch firing temperature. The main constituents of slag formed glass consisted of wallstonite and glassy phase. It is believed that the controlling the slag particle size and the amount of $Na_2SO_4$ in the slag batch will probably be main factors in foam formation.

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Influence of Machining on Magnetic Properties of Soft Magnetic Composites

  • Igarashi, Kazunori;Miyahara, Masahisa;Morimoto, Koichiro
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.1175-1176
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    • 2006
  • Influences of machining on magnetic properties of soft magnetic composites (SMC's) with addition of two kinds of binder, i.e., organic binder and inorganic one, were investigated. Machining does not affect DC magnetic properties of the SMC compacts. This can be ascribed to their particular structure in which the ironpowder particles are highly isolated by the binder. On the other hand, decrease in resistivity and resultant increase in eddy current loss was confirmed in the machined compacts containing inorganic binder. It is supposed that the brittleadditive binder existing between the iron particles is partly broken, and iron-to-iron contact is formed on the machined surface.

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Investigation on DHF Application at Metal CMP Cleaning Process (Metal CMP 세정 공정에서 DHF 적용에 관한 연구)

  • 김남훈;김상용;김인표;장의구
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.7
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    • pp.569-572
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    • 2003
  • In this study, we evaluated the dilute HF cleaning to reduce residual defects made by metal CMP process. The purpose of this test is to observe the existence of barrier metal damage during DHF cleaning on condition that it should not affect metal thin film reliability, so we will get rid of slurry residual particles as a main defect of the metal CMP process for the better yield. In-line defect data showed us that slurry residual particles were removed by DHF application. The HF rinse significantly reduced metal contamination levels and surface roughness. The best effect by additional oxide loss was discovered when Dilute HF condition is 10".

Soil Loss Reduction and Stabilization of Arsenic Contaminated Soil in Sloped Farmland using CMDS (Coal Mine Drainage Sludge) under Rainfall Simulation (광산지역 비소오염 경사 농경지 토양의 안정화 및 유실 저감을 위한 석탄광산배수슬러지의 적용성 평가)

  • Koh, Il-Ha;Kwon, Yo Seb;Jeong, Mun-Ho;Ji, Won Hyun
    • Journal of Soil and Groundwater Environment
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    • v.26 no.6
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    • pp.18-26
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    • 2021
  • Soil aggregation begins with flocculation of clay particles triggered by interfacial reactions of polyvalent cation such as Ca2+ and Fe3+, and they are also known as important elements to control the mobility of arsenic in soil environment. The objective of this study was to investigate the feasibility of CMDS (coal mine drainage sludge) for soil loss reduction and stabilization of arsenic-contaminated soil in a 37% sloped farmland under rainfall simulation. The amount of soil loss decreased by 43% when CMDS was applied, and this result was not significantly different from the case of limestone application, which yielded 46% decrease of soil loss. However, the relative amount of dispersed clay particles in the sediment CMDS-applied soil was 10% lower than that of limestone-applied soil, suggesting CMDS is more effective than limestone in inducing soil aggregation. The concentrations of bioavailable arsenic in CMDS amended soil decreased by 46%~78%, which was lower than the amount in limestone amended soil. Therefore, CMDS can be used as an effective amendment material to reduce soil loss and stabilize arsenic in sloped farmland areas.