• Title/Summary/Keyword: Internal-Mixing

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Improvement of Color and Luminance Uniformity of the Edge-Lit Backlight Using the RGB LEDs

  • Son, Chang-Gyun;Yi, Jong-Hoon;Gwag, Jin-Seog;Kwon, Jin-Hyuk;Park, Gyeung-Ju
    • Journal of the Optical Society of Korea
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    • v.15 no.3
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    • pp.272-277
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    • 2011
  • The effect of the M-window color mixing bar on the characteristics of color mixing and hot spots in the edge-lit backlight employing red (R), green (G), blue (G) light emitting diodes (LED) were studied in terms of the structure of the M-window color mixing bar. The rays from RGB LEDs entering the M-window bar were mixed by internal reflection and scattering inside the M-window bar so that the hot spots and color separation were minimized. The M-window bar was designed and fabricated and the simulation results are matched quite well to experimental data.

An Analysis of Internal Flow of Diagonal Flow Blower with Quasi-Three-Dimensional Calculation Method Considering the Spanwise Mixing due to Secondary Flow (이차흐름에 의한 스팬방향의 믹싱효과를 고려한 준3차원 계산법을 이용한 사류송풍기 내부흐름의 해석)

  • Park, S.R.;Kim, Y.J.;Kim, T.W.
    • Solar Energy
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    • v.19 no.4
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    • pp.21-31
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    • 1999
  • This paper presents a quasi-three-dimensional calculation method considered a spanwise mixing effect in a diagonal flow impeller. The effect of this spanwise mixing caused by spanwise distribution of blade loading is evaluated by a secondary flow theory. In order to verify the validity of this method, it is applied to the analysis of a diagonal flow fan designed under a vortex type of constant circumferential velocity and that of a free vortex. The comparison of the calculated result with experimental data shows a good agreement except the regions near the casing where the flow field is affected by the tip leakage flow.

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Three-dimensional Numerical Modeling of Water Temperature and Internal Waves in a Large Stratified Lake (대형 성층 호수의 수온과 내부파의 3차원 수치 모델링)

  • Chung, Se-Woong;Schladow, S. Geoffrey
    • Journal of Korean Society on Water Environment
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    • v.31 no.4
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    • pp.367-376
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    • 2015
  • The momentum and kinetic turbulent energy carried by the wind to a stratified lake lead to basin-scale motions, which provide a major driving force for vertical and horizontal mixing. A three-dimensional (3D) hydrodynamic model was applied to Lake Tahoe, located between California and Nevada, USA, to simulate the dominant basin-scale internal waves in the deep lake. The results demonstrated that the model well represents the temporal and vertical variations of water temperature that allows the internal waves to be energized correctly at the basin scale. Both the model and thermistor chain (TC) data identified the presence of Kelvin modes and Poincare mode internal waves. The lake was weakly stratified during the study period, and produced large amplitude (up to 60 m) of internal oscillations after several wind events and partial upwelling near the southwestern lake. The partial upwelling and followed coastal jets could be an important feature of basin-scale internal waves because they can cause re-suspension and horizontal transport of fine particles from nearshore to offshore. The internal wave dynamics can be also associated with the distributions of water quality variables such as dissolved oxygen and nutrients in the lake. Thus, the basin-scale internal waves and horizontal circulation processes need to be accurately modeled for the correct simulation of the dissolved and particulate contaminants, and biogeochemical processes in the lake.

Analysis on the Analytical Behavior of Soft Ground Reinforced with Granular Compaction Piles (GCP로 보강된 연약지반의 해석적 거동분석)

  • Kim, Min-Seok;Na, Seung-Ju;Yang, Yeol-Ho;Kim, Daehyeon
    • Journal of the Korean Geosynthetics Society
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    • v.15 no.3
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    • pp.27-37
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    • 2016
  • Although many studies on the Granular Compaction Pile (GCP) have been done by many researchers, the GCP design has not been systematically done due to the absence of the rational design methodology. As the GCP design has been mostly done by engineers' own experiences, some failure cases have been reported to occur. For this reason, it is very difficult to confirm definite causes of the failure and establish the prevention plans for the failure. Therefore, this study aims to investigate the optimal mixing ratio of gravel and sand, the effects of the internal friction angle of the GCP on the stress concentration ratio and the vertical and horizontal settlements. In order to analyze the behavior of the soft ground reinforced with the GCP depending on the different design parameters such as the stress concentration ratio and the internal friction angle, a number of finite element (FE) analyses were performed. From the direct shear test, the optimal mixing ratio of gravel to sand was found to be 70:30. Based on the numerical analyses, as the internal friction angle increased, the stress concentration ratio increased and it converged to a constant value. In addition, the larger the internal friction angle, the smaller the settlements. Consequently, the use of the optimal mixing ratio of gravel and sand can lead to reducing both the lateral flow and the heaving phenomenon.

Evaluation of Fundamental Properties and Chloride Penetration Resistance of Concrete using Superabsorbent Polymers (고 흡수성 폴리머를 혼입한 콘크리트의 기초 물성 및 염화물 침투 저항성 평가)

  • Lee, Chan-Kyu;Kim, Il-Sun;Choi, So-Yeong;Yang, Eun-Ik
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.2
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    • pp.50-59
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    • 2020
  • Superabsorbent Polymer (SAP) expands inside concrete by absorbing water and contracts as it discharges water. Through this process, concrete can achieve the internal curing effect, but the space occupied by the expanded SAP remains as a void. In this study, the effects of SAP internal curing and voids were evaluated by evaluating the fundamental properties and chloride penetration resistance of SAP mixed concrete. Also, to evaluate the internal curing effect by SAP, the tests were carried out under water and sealed curing conditions, respectively. From the result, the compressive strength of water curing did not differ significantly according to the mixing ratio of SAP. In the case of sealed curing, however, the compressive strength tended to increase as the mixing ratio of SAP increased. The internal curing effect of sealed curing was considered to have influenced the increase in compressive strength. In the case of the chloride diffusion coefficient, the diffusion coefficient tended to decrease as the mixing ratio of SAP increased. In particular, as the sealed curing is applied, the chloride penetration resistance is further improved due to internal curing effect. If the curing conditions are different, it is considered inappropriate to estimate the chloride penetration resistance by the surface electrical resistivity.

An Experimental Study on the Mixing Characteristics in a Basket Mill Using PIV/LIF Method (PIV/LIF를 이용한 Basket Mill 내부의 유동특성에 관한 실험적 연구)

  • Kim Hyun Dong;Yoon Sang Youl;Jeong Eun Ho;Ryu Seung Gyu;Kim Kyung Chun;Kim Joongel;Yoo Dal Hyun;Yang Si Young
    • 한국가시화정보학회:학술대회논문집
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    • 2004.11a
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    • pp.56-59
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    • 2004
  • An experimental study has performed to identify the mixing characteristics of basket mill by using PIV and LIF techniques. The velocity fields were measured at three sectors for each two types of basket mill model and various impeller speed. To verify the results of velocity field measurement and the concentration field, LIF measurement also was performed for three cases. There was an inactive region and a descending flow to the bottom of basket mill at the original model. But when the impeller type and the guide shape were changed, internal flow structure was improved suitably for mixing and dispersion. The improvement result in increment of inflow flow rate at the basket entrance about $10\%$.

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A Study on the Spray Characteristics of Flash Boiling Using Two Component Mixing Fuel (2성분 혼합연료를 이용한 감압비등 분무특성에 관한 연구)

  • Myong, Kwang-Jae;Yoon, Jun-Kyu
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.4
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    • pp.451-458
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    • 2009
  • This experimental study was conducted to investigate macroscopic characteristics of the flash boiling spray with tow component mixing fuel. Homogeneous Charge Compression Ignition (HCCI) is a newer combustion method for internal combustion engines to reduce nitrogen oxide and particulate matter simultaneously. But it is difficult to put this combustion method to practical use in an engine because of such problems as instability of combustion in low load operating conditions and knocking in high load operating conditions. In HCCI, combustion characteristics and exhaust emissions depend on conditions of air/fuel mixture and chemical reactions of fuel molecules. The fuel design approach is achieved by mixing two components which differ in properties such as density, viscosity, volatility, ignitability and so on. We plan to apply the fuel design approach to HCCI combustion generated in a real engine, and examine the possibility of mixture formation control using the flash boiling spray. Spray characteristics of two component fuel with a flash boiling phenomenon was investigated using Shlieren and Mie scattering photography. Test fuel was injected into a constant volume vessel at ambient conditions imitated injection timing BTDC of a real engine. As a result, it was found that a flash boiling phenomenon greatly changed spray structure, especially in the conditions of lower temperature and density. Therefore, availability of mixture formation control using flash boiling spray was suggested.

Performance Assessment of Passive Micromixer using Numerical Analysis (수치해석을 이용한 패시브 마이크로 믹서의 성능평가)

  • Lee, Jeong-Ick;Kim, Chul-Kyu
    • Journal of the Korea Convergence Society
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    • v.9 no.10
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    • pp.237-242
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    • 2018
  • A micromixer is a component of a lab-on-a-chip or microfluidic device that mixes two or more chemicals together(convergence). The purpose of this study is to assess the performance of passive micromixer of various shapes. Six shapes of micromixers were compared and three dimensional modeling was carried out to have the same hydraulic diameter. The commercial code, ANSYS Fluent, was used to simulate the internal mixing flow. A numerical analysis method is described in detail in this paper. The performance of the micromixer was compared with the mixing index and pressure drop. Consequently, the CDM-8T shape showed reasonable mixing performance and relatively low pressure drop.

Computational Study of the Axisymmetric, Supersonic Ejector-Diffuser Systems

  • Kim, Heuy-Dong;Lee, Young-Ki;Seo, Tae-Won;Raghunathan, Srinivasan
    • Proceedings of the KSME Conference
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    • 2000.04b
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    • pp.520-524
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    • 2000
  • A ejector system is one of the fluid machinery, which has been mainly used as an exhaust pump or a vacuum pump. The ejector system has often been pointed out to have only a limited efficiency because it is driven by pure shear action and the mixing action between primary and secondary streams. In the present work, numerical simulations were conducted to investigate the effects of the geometry and the mass flow ratio of supersonic ejector-diffuser systems on their mixing performance. A fully implicit finite volume scheme was applied to solve the axisymmetric Navier-Stokes equations, and the standard ${\kappa}-{\varepsilon}$ turbulence model was used to close the governing equations. The flow fields of the supersonic ejector-diffuser systems were investigated by changing the ejector throat area ratio and the mass flow ratio. The existence of the second throat strongly affected the shock wave structure inside the mixing tube as well as the spreading of the under-expanded jet discharging from the primary nozzle, and served to enhance the mixing performance.

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Characteristics on Shear Strength and Clogging Phenomenon of Bottom Ash and Rammed Aggregate Mixture Compaction Pile (쇄석과 저회의 혼합다짐말뚝의 전단강도와 Clogging 현상 규명)

  • Lee, Dongyeup;Kang, Hyongnam;Chun, Byungsik
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.3
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    • pp.33-41
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    • 2010
  • The rammed aggregate compaction pile method is widely used as soft ground improvement method because of the installed piles improve not only overall composite capacity but also discharge capacity. But the discharge capacity is declined when the clogging is generated due to the clay penetration into voids of rammed aggregate compaction pile with the time elapsed. The purpose of this study is to reduce the clogging problem occurred in rammed aggregate compaction pile constructed in the soft ground and to minimize voids of rammed aggregate compaction pile. The proper mixing ratio was determined which is based on the results of the large scale direct shear tests conducted to get strength and permeability as optimum mixing ratio of crushed stone and bottom ash. The test results indicated that the highest internal friction angle was obtained at 80:20 mixing ratio of crushed stone and bottom ash. The internal friction angle was declined when the mixing ratio of the bottom ash increased over 20%. The results of the clogging tests, presented that the mixture of 80:20 crushed stone and bottom ash is highest effective of clogging than ratio of pure crushed stone.