• Title/Summary/Keyword: Rapid Mixing

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Highly Sensitive Biological Analysis Using Optical Microfluidic Sensor

  • Lee, Sang-Yeop;Chen, Ling-Xin;Choo, Jae-Bum;Lee, Eun-Kyu;Lee, Sang-Hoon
    • Journal of the Optical Society of Korea
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    • v.10 no.3
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    • pp.130-142
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    • 2006
  • Lab-on-a-chip technology is attracting great interest because the miniaturization of reaction systems offers practical advantages over classical bench-top chemical systems. Rapid mixing of the fluids flowing through a microchannel is very important for various applications of microfluidic systems. In addition, highly sensitive on-chip detection techniques are essential for the in situ monitoring of chemical reactions because the detection volume in a channel is extremely small. Recently, a confocal surface enhanced Raman spectroscopic (SERS) technique, for the highly sensitive biological analysis in a microfluidic sensor, has been developed in our research group. Here, a highly precise quantitative measurement can be obtained if continuous flow and homogeneous mixing condition between analytes and silver nano-colloids are maintained. Recently, we also reported a new analytical method of DNA hybridization involving a PDMS microfluidic sensor using fluorescence energy transfer (FRET). This method overcomes many of the drawbacks of microarray chips, such as long hybridization times and inconvenient immobilization procedures. In this paper, our recent applications of the confocal Raman/fluorescence microscopic technology to a highly sensitive lab-on-a-chip detection will be reviewed.

Study on Wastewater of Paper Mill for Coagulant Characteristics (제지폐수의 응집특성에 관한 연구)

  • Cho, Jun-Hyung;Jeong, Won-Gu;Kim, Joon-Hwan
    • Journal of Forest and Environmental Science
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    • v.14 no.1
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    • pp.101-111
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    • 1998
  • Sedimentation characteristics SS, $BOD_5$ and removal efficiency of waste water in the tissue paper mill using milk carton were examined. Optimum dosage of coagulant, rapid mixing time and slow mixing time were determined by turbidity, SS and S-$BOD_5$ and then equation for treatment efficiency was suggested. For the coagulant, polyaluminium chloride(PAC) are compared with a little better efficiency compare to the aluminium sulfate.

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A Study on the Combustion Characteristics in an Aero-Valved Pulsating Combustion System (空氣밸브型 脈動燃燒시스템의 燃燒特性에 관한 硏究)

  • 임광렬;오상헌;최병륜
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.2
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    • pp.328-337
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    • 1988
  • Experimental study was carried out to investigate the combustion characteristics of the hero-valved pulsating combustor with maximum operating capacity of 56kW. The pressure, the ion current, and the temperature fluctuations were simultaneously measured and statistically analyzed to identify the combustion process, the reignition and the mixing process of the reactants. It was found that the pulse combustion process was intermittent and the reignition of the reactants was caused by a direct contact and rapid mixing with the previous hot residuals. The analysis of the measured data indicated that the combustion process consisted of there stages in the combustion chamber; the preheating of the reactants in the vicinity of the air inlet pipe, the explosive combustion in the central region and the afterburning in the vicinity of the tailpipe. Wile the inflow of the fresh air occurred during the negative period of the pressure in the mechanical valved system, it occurred during the rising period of the pressure in the aero-valved system.

A Study on the Thermal and Chemical Characteristics of Wasted Coal for the Development of Low Cost Fuel

  • Lee, G.H.;Shim, J.D.
    • Agricultural and Biosystems Engineering
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    • v.3 no.2
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    • pp.79-84
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    • 2002
  • The seawater involving diverse chemical elements was mixed with wasted coals to improve the quality. The thermal and chemical characteristics of these seawater-mixed coals were investigated and compared with those of original coals. The contents of MgO, $Na_2O$, and $K_2O$ were increased by mixing seawater in wasted coals. The content of $Na_2O$ in these coal samples was greatly increased due to the sodium, which was the main component of seawater. Thus, it was expected that fusion temperatures of these coal samples were decreased. Coal samples mixed with seawater showed that the rapid weight loss was started at the lower temperature than those of original coal samples. In these coal samples, the temperatures of maximum heat emission were lowered by average $61^{\circ}C.$. Thus, it is suggested that some chemical constituents of the seawater act an important role on lowering the ignition temperature of wasted coal. By mixing seawater into wasted coals, the calorific values were increased. Especially, calorific values were greatly increased in the coal samples of lower quality as Baksan A and B with the improvement of 15~20%.

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Burner combustion characteristics of hybrid type water mixing emulsion fuel (하이브리드형 물혼합 에멀젼 연료의 버너 특성)

  • Kim, Cheol-Jeong;Kim, Dong-Kwon;Park, Kweon-Ha
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.4
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    • pp.308-315
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    • 2013
  • Water emulsion technology has the problem of unstable combustion due to the rapid separation of water. To solve the problem, a hybrid mixing device was developed. The device attached on the burner was tested. As a result, the fuel consumption reduced to 12% in the similar condition of exhaust emissions and flame temperature, and 45.5%, 98.5% and 97.2% of NOx, CO, and smoke were reduced at the same inlet air and fuel flow rate.

Experimental Study on Fuel/Air Mixing using the Cavity in the Supersonic Flow (초음속 유동장 내의 공동을 이용한 연료/공기 혼합에 관한 실험적 연구)

  • Kim Chae-Hyoung;Jeong Eun-Ju;Jeung In-Seuck
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2005.11a
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    • pp.64-71
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    • 2005
  • To achieve efficient supersonic combustion within a manageable length, a successful fuel injection scheme must provide rapid mixing between fuel and airstream. In former days, various injection concepts have been investigated. Cavity flow is the open type, that is, length-to-depth ratio L/D=4.8, aft ramp angle is $22.5^{\circ}$. An experimental study on a transverse cross jet injection into a Mach 1.92 supersonic main stream which flows over a cavity was carried out to investigate the effect of the momentum flux ratio(J), the jet interaction characteristics, and the pressure distribution in the combustor and using the primary diagnostics : schlieren visualization and wall static pressure measurements. Fuel penetration height and jet interaction characteristics depend strongly on the momentum flux ratio.

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Traffic Extraction and Verification for Attack Detection Experimentation (공격탐지 실험을 위한 네트워크 트래픽 추출 및 검증)

  • Park, In-Sung;Lee, Eun-Young;Oh, Hyung-Geun;Lee, Do-Hoon
    • Convergence Security Journal
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    • v.6 no.4
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    • pp.49-57
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    • 2006
  • Firewall to block a network access of unauthorized IP system and IDS (Intrusion Detection System) to detect malicious code pattern to be known consisted the main current of the information security system at the past. But, with rapid growth the diffusion speed and damage of malicious code like the worm, study of the unknown attack traffic is processed actively. One of such method is detection technique using traffic statistics information on the network viewpoint not to be an individual system. But, it is very difficult but to reserve traffic raw data or statistics information. Therefore, we present extraction technique of a network traffic Raw data and a statistics information like the time series. Also, We confirm the validity of a mixing traffic and show the evidence which is suitable to the experiment.

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CFD ANALYSIS ON THE CHARACTERISTICS FOR FLOCCULATORS OF VERTICAL PADDLE AND HYDRO-FOIL TYPE (수직 패들형 및 하이드로 포일형 응집기 특성의 전산유체역학 해석)

  • Shin, J.H.;Chang, S.M.;Cho, Y.
    • Journal of computational fluids engineering
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    • v.21 no.3
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    • pp.24-30
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    • 2016
  • In the water purification plant, the mixture of water and chemical from the mixing basin enters the flocculation basin. The rotating flocculators are generally used for the efficient flocculation of dregs. In this paper, the performance of flocculators of a vertical paddle type, widely used in the typical flocculation basins, and a hydro-foil type, recently disseminated in the field, are compared with each other by use of the numerical method. Also the characteristics and the efficiency are analyzed with CFD techniques. The strain rate and the eddy viscosity are compared for two types to predict the mixing efficiency, and the maximum speed and its location are pursued from the computed data. The hydrofoil type shows that the eddy viscosity is enhanced 1.66 to 3.03 times larger than that of vertical paddle type, and also produced 1.87 to 1.95 times larger flocs for each stage. However, the rapid rotation of hydrofoil may chop the floc to small size due to the higher turbulence intensity. From the result of computation, the strong and weak points of each type have been analyzed for the decision making.

Investigation on the Turbulence Structure of Reattaching Separated Shear Layer Past a Two-Dimensional Vetrical Fenc(I) (2次元 垂直壁을 지니는 再附着 剝離 斷層 의 亂流構造 에 관한 硏究 (I))

  • 김경천;정명균
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.9 no.4
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    • pp.403-413
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    • 1985
  • Hot-wire measurements of second and third-order mean products of velocity fluctuations have been made in the separated, reattached, and redeveloping boundary layer behind a vertical fence. Mean velocity, wall static pressure distributions have also been measured in the whole flow field. Upstream of the reattachment point, the separated shear layer developes as a free mixing layer, but the gradient of the maximum slope thickness, turbulent intensities and the Reynolds shear stress are higher than that of the mixing layer due to initial streamline curvature and the effects of highly turbulent recirculating flow region. In the reattachment region, Reynolds shear stress and triple products near the surface is far more rapid than the decrease of the shear stress; that is the presence of the solid wall has a marked effect on the apparent gradient diffusivity of intensity or shear stress and throws doubts upon the usefulness of the simple gradient diffusivity model in this region.

Quantitative Determination of Nicotine in a PDMS Microfluidic Channel Using Surface Enhanced Raman Spectroscopy

  • Jung, Jae-hyun;Choo, Jae-bum;Kim, Duck-Joong;Lee, Sang-Hun
    • Bulletin of the Korean Chemical Society
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    • v.27 no.2
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    • pp.277-280
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    • 2006
  • Rapid and highly sensitive determination of nicotine in a PDMS microfluidic channel was investigated using surface enhanced Raman spectroscopy (SERS). A three-dimensional PDMS microfluidic channel was fabricated for this purpose. This channel shows a high mixing efficiency because the transverse and vertical dispersions of the fluid occur simultaneously through the upper and lower zig zag-type blocks. A higher efficiency of mixing could also be obtained by splitting each of the confluent streams into two sub-streams that then joined and recombined. The SERS signal was measured after nicotine molecules were effectively adsorbed onto silver nanoparticles by passing through the three-dimensional channel. A quantitative analysis of nicotine was performed based on the measured peak area at 1030 $cm^{-1}$. The detection limit was estimated to be below 0.1 ppm. In this work, the SERS detection, in combination with a PDMS microfluidic channel, has been applied to the quantitative analysis of nicotine in aqueous solution. Compared to the other conventional analytical methods, the detection sensitivity was enhanced up to several orders of magnitude.