• Title/Summary/Keyword: bubble size

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Studies on the Deodorization in the Nightsoil Treatment Plant with liquid Phase Catalytic Oxidation Method by Utilization of Fe-EDTA (Fe-EDTA계 액상촉매 산화법에 의한 분뇨처리장 악취제거에 관한 연구)

  • 이인화
    • Journal of Environmental Science International
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    • v.1 no.2
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    • pp.105.1-113
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    • 1992
  • The present study was performed to develop the removal system of the offensive gases, including hydrogen sulfide of acid gas, ammonia or amice of base gas, from the nightsoil treatment plant. In order to remove the offensive gases, the Fe-EDTA system liquid phase catalytic oxidation method with the bubble lift column reactor was employed. From the results obtained, it was confirmed that the offensive gases can be deodorized simultaneously and also hydrogen sulfide of acid gas, ammonia of base gas completely removed at pH 6.45. In addition, as input gases feed rate the efficiency of acid gas did not change but the efficiency of base gases decreased to approximately 90 % at pH 6, 0. From the result of particle size analyzer, it was found that the particle sizes including sulfur and other impurites grew up to $21{\mu}m$ over 72hour reaction time.

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UNSTEADY SUPERSONIC INLET DIFFUSER FLOWS WITH SINUSOIDAL PRESSURE OSCILLATIONS

  • Jong Yun Oh
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 1996.11a
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    • pp.107-116
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    • 1996
  • Numerical simulations have been conducted to characterize unsteady flow structures in an axisymmetric supersonic inlet diffuser with sinusoidal pressure oscillations at the diffuser exit. The formulation is based on the unsteady Navier-Stokes equations and turbulence closure is achieved using a two-layer model with a too-Reynolds-number scheme for the near-wall treatment. The governing equations are formulated in an integral form, and are discretized by the four-stage Runge-Kutta scheme for temporal terms and the Harten-Yee upwind TVD scheme for convective terms. Results indicated that the inlet shock characteristics are significantly modified by acoustic oscillations originating from the combustor. The characteristics of shock/boundarv-layer interactions (such as the size of separation bubble, terminal shock shape, and vorticity intensity) are also greatly iufluenced by the shock oscillation due to acoustic waves.

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Study on the insulation of HTS bushing at cryogenic temperature

  • Kim, W.J.;Shin, H.S.;Park, T.S.;Kim, S.H.
    • Progress in Superconductivity and Cryogenics
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    • v.15 no.3
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    • pp.20-23
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    • 2013
  • In the development of high temperature superconducting (HTS) power machines, HTS bushing is one of core technologies. In particular, the insulation body with sheds and electrical insulation at cryogenic temperature have attracted a great deal of interest from the view point of the size, weight and efficiency of bushing. In this study, the electrical and mechanical characteristics of various insulators for body in liquid nitrogen ($LN_2$) were investigated. And the surface discharge distance, collar length of GFRP sheds were studied. To emit bubbles between sheds, the shape and arrangement of shed were studied. The shed structure for 60 kV class HTS bushing were designed with regular arrangement.

Experimental analysis of pultrusion process for phenolic foam composites (발포 복합재료 Pultrusion 공정의 실험적 해석)

  • Yun MyungSeok;Lee WooIl
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.10a
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    • pp.143-146
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    • 2004
  • Pultrusion process of phenolic foam composite is investigated. Phenolic foam composites provide heat and flame resistance with less weight. When made into foam, a variety of properties can be obtained with different bubble size and number density. In this study, effect of process variables on the foaming characteristics of phenolic resin composites during pultrusion process has been studied experimentally. The process variables considered are the heating temperature and the pulling speed as well as the mass fraction of blowing agent. Experiments were performed using a laboratory scale pultrusion apparatus. Optimal process condition was found by observing the micro-morphology.

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Optimal Design for the Low Drag Tail Shape of the MIRA Model (MIRA model 후미의 저저항 최적 설계)

  • Kim Wook;Hur Nahmkeon
    • 한국전산유체공학회:학술대회논문집
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    • 1998.05a
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    • pp.67-74
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    • 1998
  • Reducing drag of vehicles are the main concern for the body shape designers in order to lower fuel consumption rate and to aid the driving stability. The drag of bluff bodies like transportation vehicles is mostly pressure drag due to the flow separation, which can minimized by controlling the location and size of the separation bubble. In the present study, the TURBO-3D code is incorporated with optimal algorithm based on analytical approximation method to obtain optimal afterbody shape of the MIRA Model corresponding to the lowest drag coefficient. For this purpose three mutually independent afterbody angles are chosen as design variables, while the drag coefficient is chosen as an objective function. It is demonstrated in the present study that an optimal body shape having lowest drag coefficient which is about $6\%$ lower than that of the original shape has been successfully obtained within number of iterations of the optimal design loop.

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Experimental Investigation of Two-dimensionality of Flow around the Vertical Fence Submerged in a Turbulent Boundary Layer (난류 경계층에 잠긴 수직벽 주위 유동의 2차원성 연구)

  • Cha, Jae-Eun;Kim, Hyoung-Woo;Kim, Hyoung-Bum
    • Journal of the Korean Society of Visualization
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    • v.8 no.1
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    • pp.13-18
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    • 2010
  • An experimental investigation of the flow around a vertical fence was carried out using a PIV velocity field measurement technique. The vertical fence was embedded in a turbulent boundary layer. The instantaneous velocity fields measured at cross-sectional planes reveal complex longitudinal vortices that vary in size and strength, developing from the upstream location. In the instantaneous vorticity and velocity field data, the shear flow separated from the fence top is highly turbulent and shows unsteady flow characteristics. The topography of the ensemble averaged velocity fields, especially the separation bubble formed behind the fence, shows that the spatial distributions of streamwise velocity (U) and vertical (V) are symmetric, the spanwise velocity (W) is skew-symmetric with respect to the central xy-plane(z=0).

Studies on the flow stabilization around the turbine suction with utilizing the surface water overflow at small-hydraulic power plant (표층수의 월류를 통한 소수력빌전소 수차터빈측의 유동안정화 연구)

  • Lee, Sungmyung;Kim, Cheolhan;Yoo, Gunjong;Kim, Wonseok
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.11a
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    • pp.165.2-165.2
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    • 2011
  • Flow with suction to water turbine must be in stable state at small hydraulic power plant. But because of water level fluctuation and water gate effect according to irregular supply of cooling water, it would happen to produce bubble and vortex and finally lead to problems in power-plant system. With utilizing the concept design of double size gate, surface water overflowed the overhead of gate for stable flow at suction. We developed the overflow condition and analyzed the design factor with existed one such as water level(overflow amount) and overhead of water gate(overflow figure). Flow test and CFD simulation say that flow have stable state around suction and 20% of wave reduction effect at surface layer after surface water overflow.

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Development of digital textile design using marbling dyeing technique and Photoshop for DTP (포토샵을 이용하여 공예적 기법인 마블링 패턴을 DTP 출력용 텍스타일 디자인으로 개발)

  • Kim, Sin-Hee
    • Journal of Fashion Business
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    • v.13 no.2
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    • pp.115-122
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    • 2009
  • Marbling dyeing technique shows beautiful flowing pattern because the pattern is transferred to the medium by the pigments floating onto the viscous solution base. However, this marbling pattern does not have any reproducibility and the result of accidental pattern formation. Marbling process contains many complicated procedures such as making marbling base, mordanting the medium, and bubble removal with size limitation. Computer changed the many aspects in textile design and digital technique is used in many design production. However, it is impossible to produce marbling pattern with digital drawing. In this research, the digital textile design starting from marbling pattern was developed for digital textile printing. Marbling was done to produce the initial motifs and scanned. Several marbling media such as silk, polyester, and paper were used. Photoshop was used to process and develop textile design based on these marbling motifs. One repeat was developed and various colorways were tried. The developed textile design were printed using DTP.

Integrated dynamics modeling for supercavitating vehicle systems

  • Kim, Seonhong;Kim, Nakwan
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.2
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    • pp.346-363
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    • 2015
  • We have performed integrated dynamics modeling for a supercavitating vehicle. A 6-DOF equation of motion was constructed by defining the forces and moments acting on the supercavitating body surface that contacted water. The wetted area was obtained by calculating the cavity size and axis. Cavity dynamics were determined to obtain the cavity profile for calculating the wetted area. Subsequently, the forces and moments acting on each wetted part-the cavitator, fins, and vehicle body-were obtained by physical modeling. The planing force-the interaction force between the vehicle transom and cavity wall-was calculated using the apparent mass of the immersed vehicle transom. We integrated each model and constructed an equation of motion for the supercavitating system. We performed numerical simulations using the integrated dynamics model to analyze the characteristics of the supercavitating system and validate the modeling completeness. Our research enables the design of high-quality controllers and optimal supercavitating systems.

VARIATION OF LOCAL POOL BOILING HEAT TRANSFER COEFFICIENT ON 3-DEGREE INCLINED TUBE SURFACE

  • Kang, Myeong-Gie
    • Nuclear Engineering and Technology
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    • v.45 no.7
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    • pp.911-920
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    • 2013
  • Experimental studies on both subcooled and saturated pool boiling of water were performed to obtain local heat transfer coefficients on a $3^{\circ}$ inclined tube of 50.8 mm diameter at atmospheric pressure. The local values were determined at every $45^{\circ}$ from the very bottom to the uppermost of the tube periphery. The maximum and minimum local coefficients were observed at the azimuthal angles of $0^{\circ}$ and $180^{\circ}$, respectively, in saturated water. The locations of the maxima and the minima were dependent on the inclination angle of the tube as well as the degree of subcooling. The major heat transfer mechanisms were considered to be liquid agitation generated by the sliding bubbles and the creation of big size bubbles through bubble coalescence. As a way of quantifying the heat transfer coefficients, an empirical correlation was suggested.