• Title/Summary/Keyword: flow induction

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An Experimental Study of In-Cylindeer Flow Characteristics of a High Speed Direct Injection Diesel Engine (고속 직접분사식 디젤엔진의 실린더내 유동특성에 관한 실험적 연구)

  • 정경석
    • Transactions of the Korean Society of Automotive Engineers
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    • v.4 no.3
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    • pp.22-30
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    • 1996
  • In-cylinder flow of a purpose-built small HSDI Hydra Diesel engine was investigated by laser Doppler velocimetry(LDV) during induction and compression processes. The flow was quantified in terms of ensemble-averaged axial and swirl velocities, normalized by the mean piston speed, at a plane located 12mm from the cylinder head and corresponding to the mid-plane of the diametrically-opposed quartz windows at an enigne speed of 1000rpm. The formation of toroidal vortices during the intake process and the evolution and decay of swirl motion during the compression process were observed. Turbulence at around TDC of compression became homogeneous and isotropic.

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The Analysis of Liquid Metal Flow Characteristics in the Annular Passage of an Electromagnetic Pump

  • Kim, Chang-Eob;Jeon, Mun-Ho;Kwon, Jeong-Tae;Lim, Hyo-Jae;Lee, Suk-Won
    • Journal of Electrical Engineering and Technology
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    • v.5 no.2
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    • pp.270-275
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    • 2010
  • An electromagnetic pump using a tubular induction motor (TLIM) has been proposed to pump liquid metal fluids. TLIM has been designed for liquid metal flow systems with a motor with a thrust force of 40~77[N]. The flow characteristics have been investigated by solving the Navier-Stokes equation, where the Lorentz force was included simply by considering it as a constant in the Navier-Stokes equation. A wood metal was chosen to simulate the liquid metal. The effect of Lorentz force on the flow rate was investigated. An experiment was conducted and its results were compared with those of the simulation. The simulation result showed an overestimation of about 17% compared with the experimental one.

Analysis of aerodynamic characteristics of 2 MW horizontal axis large wind turbine

  • Ilhan, Akin;Bilgili, Mehmet;Sahin, Besir
    • Wind and Structures
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    • v.27 no.3
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    • pp.187-197
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    • 2018
  • In this study, aerodynamic characteristics of a horizontal axis wind turbine (HAWT) were evaluated and discussed in terms of measured data in existing onshore wind farm. Five wind turbines (T1, T2, T3, T4 and T5) were selected, and hub-height wind speed, $U_D$, wind turbine power output, P and turbine rotational speed, ${\Omega}$ data measured from these turbines were used for evaluation. In order to obtain characteristics of axial flow induction factor, a, power coefficient, $C_p$, thrust force coefficient, $C_T$, thrust force, T and tangential flow induction factor, a', Blade Element Momentum (BEM) theory was used. According to the results obtained, during a year, probability density of turbines at a rotational speed of 16.1 rpm was determined as approximately 45%. Optimum tip speed ratio was calculated to be 7.12 for most efficient wind turbine. Maximum $C_p$ was found to be 30% corresponding to this tip speed ratio.

A study on the Analysis and Forecast of Effect Factors in e-Learning Reuse Intention Using Rule Induction Techniques (규칙유도기법을 이용한 이러닝 시스템의 재이용의도 영향요인 분석 및 예측에 관한 연구)

  • Bae, Jae-Kwon;Kim, Jin-Hwa;Jeong, Hwa-Min
    • Journal of Information Technology Applications and Management
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    • v.17 no.2
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    • pp.71-90
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    • 2010
  • Electronic learning(or e-learning) has created hype for companies, universities, and other educational institutions. It has led to the phenomenal growth in the use of web-based learning and experimentation with multimedia, video conferencing, and internet-based technologies. Many researchers are interested in the factors that affect to the performance of e-learning or e-learning services. In this sense, this study is aimed at proposing e-learning system reuse prediction models in which e-learner intention to reuse influence factors(i.e., system accessibility, system stability, information clarity, information validity, self-regulated efficacy, computer self-efficacy, perceived usefulness, perceived ease of use, flow, and parental expectation) affect e-learner intention to reuse positively. A web survey was conducted for the full members of the e-learning education institute A in Seoul, Republic of Korea, an exclusive e-learning company that provides real time video lectures via the desktop conferencing system. The web survey was conducted for 20 days from November 5, 2009, through the e-learning web site of the company A. In this study, three data mining techniques were used : the multivariate discriminant analysis, CART, and C5.0 algorithm. This study was conducted to provide the e-learning service providers, e-learning operators, and contents developers with marketing and management strategies for improving the e-learning service companies, based on the data mining analysis results.

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On the two phase detonation in carbon laden oxygen : taking into account of inner particle temperature distribution (입자온도 분포를 고려한 탄소입자와 산소에서의 이상폭발현상에 관한 연구)

  • 승성표;백승욱
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.5
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    • pp.1104-1112
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    • 1988
  • In this study the structure of a two phase detonation has been numerically investigated through the assumption of a steady and one-dimensional flow in the suspension of carbon particles and pure oxygen. The bow shock formation in front of carbon particles has been taken into consideration when the relative velocity of gas flow with respect to the particle exceeds the local speed of sound. But its effect was found to be very limited to the induction zone only. Furthermore the interior particle temperature distribution has been considered in this work. It was found that the inner temperature gradient was very steep in the region of high relative velocity. On the while the temperature distribution inside the particle was almost uniform in the region of low relative velocity. Overall, the effect of the interior particle temperature distribution has been significant in the two phase detonation.

Analysis on the In-cylinder Flow of HIMSEN 6H21/32 Engine (HIMSEN 6H21/32 엔진 실린더 내 유동해석)

  • Yoon, Wook-Hyun;Kim, Jin-Won;Ha, Ji-Soo
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.934-939
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    • 2001
  • In computational study of the flow in piston engines and the flow through moving valves, the use of moving vertices is essential for modelling flows with moving boundaries. The positions of cell vertices in such cases must be allowed to vary with time. To simulate 3-dimensional port-valve and piston-cylinder of HIMSEN 6H21/32 engine, a commercially available code, STAR-CD, was used. Changes in mesh geometry was specified by PROSTAR commands.(i.e. the Change Grid operation in the EVENTS command module.) Control of the intake flow is expected to play an important role as designers seek to obtain better fuel spray characteristics, fuel mixing and mixture preparation, combustion performance, and emissions reductions to meet national standards. As a result of analysis, velocity fields indicate the presence of a structured flow comprised of one pair of counter-rotating vortices under the intake valve during the early induction process. These flow structures remain visible for most of the intake process. As the piston moves towards BDC, these vortices develops into a larger tumbling motion that dominates the flow structure.

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Synthesis of high purity aluminum nitride nanopowder by RF induction thermal plasma (유도결합 열 플라즈마를 이용한 고순도 질화알루미늄 나노 분말 합성)

  • Kim, Kyung-In;Choi, Sung-Churl;Han, Kyu-Sung;Hwang, Kwang-Taek;Kim, Jin-Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.24 no.1
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    • pp.1-7
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    • 2014
  • Aluminum nitride, which has outstanding properties such as high thermal conductivity and electrical resistivity, has been received a great attention as a substrate and packaging material of semiconductor devices. Since aluminum nitride has a high sintering temperature of 2173 K and its properties depends on the impurity level, it is necessary to synthesize high-purity and nano-sized aluminum nitride powders for the applications. In this research, we synthesized high purity aluminum nitride nanopowders from aluminum using RF induction thermal plasma system. Sheath gas (NH3) flow was controlled to establish the synthesis condition of high purity aluminum nitride nanopowders. The obtained aluminum nitride nanopowders were evaluated by XRD, SEM, TEM, BET, FTIR and N-O analysis.

Directional effects of close-up shot in Development of Narrative - Focusing on Animation - (내러티브 전개에서의 클로즈업 쇼트의 연출 효과 - 애니메이션을 중심으로-)

  • Lee, Tae-Gu
    • Journal of Digital Contents Society
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    • v.15 no.1
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    • pp.53-60
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    • 2014
  • Even if shots in frames may be variable in both movies and animations, close-up reveals the significance of the subject in the focus. Because directors and animators take the place the actor as character in animation while performance of actor plays an important role in the close-up in the movies, it is significant to understand the close-up in the animation. In the present study we investigate the dramatic effect of close-up in the animation narrative in animations for theaters. Among the various dramatic effects of the close-up, the natural flow of the narrative and the induction of immersing in emotion are focused. Descriptive close-up is analyzed as a dramatic effect of inducing the natural flow of the narrative. Psychological close-up is analyzed as the induction of immersing emotion by effective delivery of internal mental state of a character. By analyzing symbolic close-up as the induction of immersing in the play by producing a dramatic effect, we expect that the close-up contribute to the advance of animation narrative structure.

A numerical study on the aerodynamic characteristics of a variable geometry throttle valve(VGTV) system controlling air-flow rate (유량 제어장치인 가변스로틀밸브의 기하학적 형상변화에 따른 공기역학 특성분석 연구)

  • Cho, Hyun-Sung;Kim, Chul-Ho
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.4
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    • pp.378-383
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    • 2013
  • A butterfly throttle valve has been used to control the brake power of an SI engine by controlling the mass flow-rate of intake air in the induction system. However, the valve has a serious effect on the volumetric efficiency of the engine due to the pressure resistance in the induction system. In this study, a new intake air controlling valve named "Variable Geometry Throttle Valve(VGTV)" is proposed to minimize the pressure resistance in the intake system of an SI engine. The design concept of VGTV is on the application of a venturi nozzle in the air flow path. Instead of change of the butterfly valve angle in the airflow field, the throat width of the VGTV valve is varied with the operating condition of an SI engine. In this numerical study, CFD(computational fluid dynamics) simulation technique was incorporated to have an aerodynamics performance analysis of the two air flow controlling systems; butterfly valve and VGTV and compared the results to know which system has lower pressure resistance in the air intake system. From the result, it was found that VGTV has lower pressure resistance than the butterfly valve. Especially VGTV is effective on the low and medium load operating condition of an SI engine. The averaged pressure resistance of VGTV is about 49.0% lower than the value of the conventional butterfly throttle valve.

Analysis of Membrane Fouling Reduction by Natural Convection Instability Flow in Membrane Filtration of Protein Solution Using Blocking Filtration Model (막힘여과 모델에 의한 단백질 용액의 막여과에서 자연대류 불안정 흐름의 막오염 제어 효과 해석)

  • Kim, Ye-Ji;Youm, Kyung-Ho
    • Membrane Journal
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    • v.29 no.1
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    • pp.18-29
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    • 2019
  • The dead-end ultrafiltration (UF) of BSA protein solution was performed to investigate the defouling effects of natural convection instability flow (NCIF) induced in membrane module. The permeate fluxes were measured according to the inclined angles ($0{\sim}180^{\circ}$) of membrane module with respect to gravity, and analyzed using the blocking filtration model. NCIF are more induced as the inclined angles increased from $0^{\circ}$ to $180^{\circ}$, and the induced NCIF enhances flux. Comparing the fluxes at $0^{\circ}$ inclined angle (no NCIF induction) and $180^{\circ}$ (maximum NCIF induction), the flux enhancements by NCIF induction are increased about 5 times in the short-term UF operation (2 hours) and about 17 times in the long-term operation (20 hours). As applying the blocking filtration model, it is more suitable to analyze the flux results by using the intermediate blocking model in the early times of UF operation within 15 minutes and then thereafter times by using the cake filtration model. NCIF induced at $180^{\circ}$ inclined angle reduces the intermediate blocking fouling at about 67% in the early times operation and thereafter the cake layer fouling at about 99.9%. The main defouling mechanism of NCIF induced in the membrane module is suppress the formation of protein cake layer.