• Title/Summary/Keyword: Minimum velocity

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A Velocity Disturbance Estimation System for the Stable Fine Seek Control Using a Genetic Algorithm (유전자 알고리즘을 이용한 안정적인 미동 탐색 제어를 위한 속도 외란 추정 시스템)

  • Jin, Kyoung Bog;Shin, Jin-Ho;Lee, Moonnoh
    • Journal of the Semiconductor & Display Technology
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    • v.11 no.3
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    • pp.13-18
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    • 2012
  • This paper presents a velocity disturbance estimation system for the stable fine seek control using a genetic algorithm. To estimate accurately the velocity disturbance in spite of the uncertainties of fine actuator, the system utilizes an objective function to minimize the differences of the frequency characteristics between the nominal velocity control loop and the extremal velocity control loops. The objective function is considered by applying a genetic algorithm and the velocity disturbance is estimated by the measurable velocity, the adjusted velocity controller, and the fine actuator model. The proposed velocity disturbance estimation system is applied to the fine seek control system of a DVD recording device and is evaluated through the experimental results.

Experimental Investigation on Particle Size of Soils Erodible by Wind using Portable Wind Erosion Tunnel (소형 풍동을 이용한 토양의 풍식 가능 입경 분석)

  • Kim, Tae-Wan;Son, Young-Hwan;Min, Seul-Gi;Lee, In-Bok;Hong, Se-Woon;Kim, Min Young
    • Journal of The Korean Society of Agricultural Engineers
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    • v.55 no.6
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    • pp.127-133
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    • 2013
  • The purpose of this study was to investigate maximum and minimum grain size which eroded by wind according to soil and wind conditions, such as top soil water content, roughness, land slope, wind velocity and proportion of grain size under 0.84mm. For performing this study, portable wind erosion tunnel was designed and utilized during field test, which facilitated measuring actual wind erosions under artificially controlled wind conditions. In the result, maximum, minimum grain size had strong negative correlation with roughness while weak positive correlation with wind velocity. Also, Slope which means the effect of gravity also influence grain size erodible by winds. Based on these results, regression equations were suggested for predicting maximum and minimum grain sizes by using multiple linear regression analysis from SPSS 20.0. The equation for maximum grain size erodible by winds showed a good agreement with the observed data with $R^2$=0.896. Other equation for minimum grain size had $R^2$=0.777.

The Characteristics of Sediment and a Design Method for Preventing Sediment in the beginning Lateral Sewer (단말 오수관거 에서의 퇴적특성과 퇴적방지를 위한 설계법 고찰)

  • Hwang, Hwan Kook;Kim, Young Jin;Han, Sang Jong;Jung, Ho Chan
    • Journal of Korean Society of Water and Wastewater
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    • v.23 no.6
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    • pp.789-797
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    • 2009
  • The flow in the beginning lateral sewer can be characterized as intermittent and unsteady, and a moment maximum flow energy is required to transport fecal solids in the sewer. It is thus difficult to design to satisfy a minimum velocity criteria (0.6m/s), because of the substantially lower discharge in the beginning lateral sewer. This study is the result of a field survey, and aims to determine a design criteria for the minimum slope to prevent sediment in a lateral sewer. The survey performed on the two flat small catchments in Goyang-si consisting of D400mm hume-pipe, aimed to understand the manner in which the scope of a sewer slope has an effect on sediment in the beginning lateral sewer. The survey showed that the sewer slope below 3‰ had sedimentation of 88.7%, while the sewer slope of 3~6‰ had sedimentation of 47.8%. In addition, the minimum design slope was estimated to refer to the result of hydraulic experiments from Public Works Research Institute in Japan. Analysis showed that the D400mm hume pipe should be installed with a slope of 6.5‰ to prevent sediment in the beginning lateral sewer. For future installations, the study results showed that a D300mm plastic pipe requires a minimum slope of 3.5‰, and a D250mm plastic pipe requires a minimum slope of 3.3‰ in the beginning lateral sewer.

Hydrodynamic Characteristics of Absorbent and Catalyst for Pre-combustion CO2 Capture (연소 전 이산화탄소 회수를 위한 흡수제 및 촉매의 수력학적 특성)

  • Ryu, Ho-Jung;Yoon, Joo-Young;Lee, Dong-Ho;Shun, Dowon;Park, Jaehyeon;Park, Yeong-Seong
    • Clean Technology
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    • v.19 no.4
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    • pp.437-445
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    • 2013
  • To develop SEWGS (sorption enhanced water gas shift) system using dry $CO_2$ absorbent for pre-combustion $CO_2$ capture, hydrodynamic characteristics of $CO_2$ absorbents were measured and investigated. The minimum fluidization velocity of $CO_2$ absorbent was measured and the effects of the operating conditions were investigated to operate the system at bubbling fluidized bed condition. The minimum fluidization velocity decreased as pressure and temperature increased. Moreover, the minimum fluidization velocity decreased as column diameter increased. The effects of operating conditions on the solid circulation rate were measured and investigated to select appropriate operating conditions for continuous $CO_2$ capture and regeneration. The measured solid circulation rates were ranged between 10 and 65 kg/h and increased as the solid injection velocity, gas velocity in the regeneration reactor, and solid height increased.

Adaptive minimum-time optimal control of robot manipulator (로보트 매니퓰레이터에 대한 적응 최소시간 최적제어)

  • 정경훈;박정일;박종국
    • 제어로봇시스템학회:학술대회논문집
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    • 1990.10a
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    • pp.258-262
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    • 1990
  • Several optimum control algorithms have been proposed to minimize the robot cycle time by velocity scheduling. Most of these algorithms assume that the dynamic and kinematic characteristics of a manipulator are fixed. This paper presents the study of a minimum-time optimum control for robotic manipulators considering parameter changes. A complete set of solutions for parameter identification of the robot dynamics has been developed. The minimum-time control algorithm has been revised to be updated using estimated parameters from measurements.

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An Experimental Study on Loss Coefficient of Turbine Cascade with Incidence Angles (입사각의 변화에 따른 터빈 캐스케이드에서 손실계수에 관한 실험적 연구)

  • Lee, Ju-Hyung;Hur, Won-Hae;Jeon, Chang-Soo
    • The KSFM Journal of Fluid Machinery
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    • v.2 no.4 s.5
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    • pp.48-56
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    • 1999
  • For the study on loss coefficients of turbine cascade with variation of incidence angle, the wind-tunnel tests were performed under the ranges in velocity of 10 m/s, 15 m/s, 20 m/s and incidence angles from $-20^{\circ}\;to\;20^{\circ}$ by intervals of $5^{\circ}$. Comparing our results with Soderberg's prediction, differences in loss coefficient were $2.5\%\;and\;2.8\%$ each for 10 m/s and 15 m/s. A large disagreement of $30.3\%$ was showed at 20 m/s freestream velocity. The comparisons of these test results with Ainley's prediction showed an $8\%$ difference in the case of 20 m/s freestream velocity. Test results were approximately comparable with Ainley's loss prediction's in incidence angles. Generally, averaged total pressure loss seemed to be decreased as Reynolds number increased. The total pressure loss coefficients were increased parabolically, as incidence angles were increased negatively and positively from $0^{\circ}$, in all speed ranges. At the far low freestream velocities, minimum loss accurred between $-5^{\circ}\;and\;+5^{\circ}$. But this minimum range narrowed the location of this range by shifting to the direction of the angle as freestream velocity was increased.

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Determination of the Minimum Instream Flows for the Landscape of Riverside (하천의 경관 유지 수량의 결정)

  • 홍형순;이주헌;정상만
    • Journal of the Korean Institute of Landscape Architecture
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    • v.30 no.6
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    • pp.17-25
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    • 2003
  • The physical components of a river, such as water surface width/river width ratio, water level, and flow velocity vary according to different flowrates. Moreover, the riverside landscapes are greatly affected by the change of physical components of the stream or river. This paper provides an analysis of the influence of changing physical components of a river on the riverside landscape using a survey-based quantification method. The questionnaire was developed based on current literature, and was submitted to 326 people who each visited a representative station along the riverside.This survey was implemented three times at each representative station during periods of different flowrates. The results of this analysis and survey have Produced an understanding of the relationship between the variation of physical components and riverside landscapes. Survey results about the flow comparison are summarized as follows. Viewing riverside landscapes, most respondents are sensitive to the change of the flow velocity and prefer high water levels to low water levels. As a whole, respondents prefer abundant stream flows and moderate flow velocity in which they can perceive the flow of water. The minimum instream flows for riverside landscapes is estimated at each representative station by using a survey-based quantification method, and the estimated results of some representative stations were greater than the mean monthly flow at each station. The result of this analysis shows that establishing minimum instream flows for riverside landscapes is not only a technical problem, but also a legal problem. Therefore, in the to establish the instream flows in a river, the estimated results have to be considered as a relative standard. Regarding the survey results, respondents' satisfaction level didn't show any clear inclination according to the variation of various hydraulic properties. In determining the minimum instream flow using such an inquiry method, the structure of riverside scenery may vary according to the change of seasons or months. Therefore, to determine a consistent general inclination about the flow rate, it is necessary to have more detailed flow rates for each season or month combined with more inquiries.

An Experimental Study on the Lift-off Characteristics of the Triple Flame within a Diverging Duct (단면 확대 덕트 내에 형성된 삼지화염의 부상특성에 관한 실험적 연구)

  • Seo, Jeong-Il;Kim, Nam-Il;Oh, Kwang-Chul;Shin, Hyun-Dong
    • 한국연소학회:학술대회논문집
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    • 2003.05a
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    • pp.85-91
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    • 2003
  • The lift-off characteristics of the triple flame within a diverging duct have been studied experimentally using a multi-slot burner, which can control the concentration gradient and the mean velocity independently. In this experiment the triple flame was stabilized successfully in lift-off condition and flame stabilization with a duct or without a duct, lift-off heights, and some other characteristics were examined for propane flame. It was examined that the effects with various concentration gradient and mean velocity on the triple flame. It was found that minimum value of the lift-off heights exist at a certain concentration gradient for constant mean velocity and flame with a duct is more stable than that without. Moreover the propagation velocity of the flame becomes maximum at a certain concentration gradient regardless of mean velocity.

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An Experimental Study on the Lift-off Characteristics of the Triple Flame with Concentration Gradient (농도구배가 삼지화염의 부상특성에 미치는 영향에 관한 실험적 연구)

  • Seo, Jeong-Il;Kim, Nam-Il;Oh, Kwang-Chul;Shin, Hyun-Dong
    • 한국연소학회:학술대회논문집
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    • 2004.06a
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    • pp.7-14
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    • 2004
  • The lift-off characteristics of the triple flame have been studied experimentally with various mean velocities and concentration gradients using a multi-slot burner, which can control the concentration gradient and the mean velocity independently, Lift-off height, axial maximum velocity, flame temperature, and some other characteristics were examined for methane and propane flame, It was found that minimum values of the lift-off heights exist at a certain concentration gradient for constant mean velocity, and this result implies that the propagation velocity has a maximum value at this condition, OH radical distribution was measured with LIF method and velocity variation along streamline was measured with PlV system. In addition maximum temperature along streamline was measured with CARS system. The intensity of the diffusion flame affects on the propagation velocity of triple flame in the region of very weak concentration gradient.

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