• Title/Summary/Keyword: flapper

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An Analytical Investigation of the Characteristics of Four-Nozzle Flapper Valve (4-노즐 플렙퍼 밸브 특성에 대한 해석적 고찰)

  • 이재천
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.161-166
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    • 2001
  • The static characteristics of four-nozzle flapper valves are investigated with both constant flow and constant supply pressure. The ranges, in which linearization of these characteristics would be valid, are discussed. Linearized dynamic model is also derived. Numerical simulations of nonlinear dynamic model are carried out by HyPneu to make an assessment of the effect of input step size in both cases of no-load and blocked-load operation.

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A Study on the Parallelism between the Art Trend and the Fashion -Focusing on Modernism and the Flapper Look (예술사조와 패션과의 Parallelism에 관한 연구 -모더니즘과 플래퍼 록을 중심으로-)

  • 정현숙;김진구
    • The Research Journal of the Costume Culture
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    • v.3 no.2
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    • pp.261-275
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    • 1995
  • This paper analyzes the parallelism between the art trend and the fashion. As a representative case, we consider the Modernism and the Flapper look. The Modernism rejected the tradition of the past and pursued something new. This trend was in parallel with the fashion called flapper look which was against the tradition and made drastic change. The factors which represent the spirit of the age the Modernism are the simplicity, the rejection of the tradition, the individualism and the subjectivity, the functionalism, the fragmentation of the self, and the straight line. We discuss the fashion style of the flapper look in terms of these factors.

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A Study On Characteristics of Nozzle/Flapper Type Flow Control Servo Valve (노즐/플래퍼형 유량제어 서보밸브의 특성에 관한 연구)

  • 윤소남;강보식;성백주;김형의
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.1
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    • pp.54-62
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    • 2000
  • The purpose of this study is to bring out the optimal design factors which effect on dynamic characteristics in the design of flow control servo valve with high response characteristics, and to verify the validity of the design factors. In this study, force feedback type flow control valve with nozzle/flapper and with no drain is studied. And, the effect of the parameters, such as fixed orifice, nozzle diameter, and maximum displacement between nozzle and flapper are analyzed. We have done simulations using the optimal design factors and simulink(Matlab) as a simulation tool, and verified the validity of our simulations by means of comparison our simulation results with an experimental results of another similar valve.

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Experimental Study on Power Improvement of a Flapping Tidal Stream Turbine by Mimicking a Manta-Ray (쥐가오리 모방 진동식 조류 터빈의 출력향상에 대한 실험적 연구)

  • Ko, Jin Hwan;Kim, Jihoon
    • Ocean and Polar Research
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    • v.39 no.4
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    • pp.293-300
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    • 2017
  • Various approaches have been tried in an effort to improve the power performance of a flapping tidal stream turbine after it was introduced as an alternative to conventional rotary turbines. Among the different approaches, researches on mimicking the morphology and behavior of animals have been conducted. In this study, we utilized a flapper to mimic the multi-joint pectoral fin of a Manta-ray and investigated its effect on power generation. Experiments were conducted by a dual flapping apparatus with rigid and flexible flappers in a towing tank facility. First, in order to determine the conditions that can produce high power generation, the performances of the dual rigid flappers were compared when input arm angles and frequencies are changed, and the two conditions $40^{\circ}$, 0.2 Hz and $40^{\circ}$, 0.3 Hz for the input arm angle, frequency were selected. When the mimicked flexible flapper was used instead of the front rigid flapper and the rear one, the power was improved by an average of 22% and 38% in the experimental conditions, respectively. Moreover, it was recognized from the apparent camber observed during the experiment that the flexible flapper had been successfully applied. If the feasibility of the Manta-Ray mimicked flapper is improved through subsequent researches, the flapping tidal turbine can be a viable alternative to rotary turbines in the near future.

A Study on Winter Season Usability Performance Improvement of Flapper Valve for KUH-1 (한국형 기동헬기 동계운용능력 향상을 위한 플래퍼밸브 개선연구)

  • Choi, Jae Hyung;Chang, In ki;Shim, Dai Sung;Ahn, Jeong Min
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.1
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    • pp.49-56
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    • 2016
  • Flapper Valve of Korean Utility Helicopter(KUH-1) is an essential equipment in Environmental Control System(ECS) for pilot to perform flight mission. It provides pilots and crews with heating, ventilating and air conditioning. It has function of maintaining room temperature to sustain operational capability for pilot and crew. This paper summarizes pilot comments in flight test which are classified by cause of occurrence and the troubleshooting process about each comment. It also describes design improvements which was derived from troubleshooting and suggests verification results of flight test at low temperature.

Dynamic Modeling and Pressure Control of Piezoactuator Based Valve Modulator Integrated with Flexible Flapper (유연 플래퍼와 연계한 압전 밸브 모듈레이터의 동적 모델링 및 압력 제어)

  • Jeon, Jun-Cheol;Maeng, Young-Jun;Sohn, Jung Woo;Choi, Seung-Bok;Lee, Soo-Jin
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.10
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    • pp.976-982
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    • 2010
  • This paper proposes a novel type of pressure control mechanism which can apply to vehicle ABS (anti-lock braking system) utilizing the piezoactuator based valve system associated with the pressure modulator. As a first step, a flapper-nozzle of a pneumatic valve system is devised by integrating the piezoacuator to the flexible beam structure. The dynamic modeling of the valve system is then undertaken and subsequently the governing equation of pressure control is derived considering the pressure modulator. A sliding mode controller is designed in order to achieve accurate pressure tracking control in the presence of actuator uncertainty as well as input pressure variation. It is shown through computer simulation that an accurate pressure tracking for sinusoidal motion whose magnitude is 40 bar is achieved by utilizing the proposed pressure control mechanism.

Simulation and transient analyses of a complete passive heat removal system in a downward cooling pool-type material testing reactor against a complete station blackout and long-term natural convection mode using the RELAP5/3.2 code

  • Hedayat, Afshin
    • Nuclear Engineering and Technology
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    • v.49 no.5
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    • pp.953-967
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    • 2017
  • In this paper, a complete station blackout (SBO) or complete loss of electrical power supplies is simulated and analyzed in a downward cooling 5-MW pool-type Material Testing Reactor (MTR). The scenario is traced in the absence of active cooling systems and operators. The code nodalization is successfully benchmarked against experimental data of the reactor's operating parameters. The passive heat removal system includes downward water cooling after pump breakdown by the force of gravity (where the coolant streams down to the unfilled portion of the holdup tank), safety flapper opening, flow reversal from a downward to an upward cooling direction, and then the upward free convection heat removal throughout the flapper safety valve, lower plenum, and fuel assemblies. Both short-term and long-term natural core cooling conditions are simulated and investigated using the RELAP5 code. Short-term analyses focus on the safety flapper valve operation and flow reversal mode. Long-term analyses include simulation of both complete SBO and long-term operation of the free convection mode. Results are promising for pool-type MTRs because this allows operators to investigate RELAP code abilities for MTR thermal-hydraulic simulations without any oscillation; moreover, the Tehran Research Reactor is conservatively safe against the complete SBO and long-term free convection operation.

A Study on the Design and the Dynamic Characteristics of Electro-Hydraulic Flow Control Servo Valve (전자유압 서보 유량제어밸브의 설계 및 동특성 향상에 관한 연구)

  • 김고도;김수태
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.2
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    • pp.151-160
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    • 2000
  • An experimental and theoretical analysis for the improvement of dynamic characteristics and design of electro-hydraulic flow control servo valve are performed. The theoretical results are compared with the experimental step responses, and the important design parameters of an electro-hydraulic flow control servo valve are derived by using the simulation program. Simulation parameters of nozzle jet coefficient and orifice and spool valve discharge coefficient are given through experiment. The theoretical and experimental step response curves show that the valve gain depends on the fixed orifice and nozzle $ratio(R_on)$ and is maximum at $R_on=1.$ And drain orifice in the flapper - nozzle return line creates a small back pressure, which improves the performance fur the valve.

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A Study on Characteristics of Flow Control Servo Valve with no Drain Orifice (드레인 오리피스가 없는 유랑제어 서보밸브의 특성에 관한 연구)

  • Yun, So-Nam;Gang, Bo-Sik;Seong, Baek-Ju;Kim, Hyeong-Ui
    • 연구논문집
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    • s.26
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    • pp.85-94
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    • 1996
  • The purpose of this study is to bring out the optimal design factors which effect on dynamic characteristics in the design of proportional flow control valve with high response characteristics, and to verify the validity of the design factors. In this study, force feedback type flow control valve with nozzle-flapper is studied. And, the influences which fixed orifice, nozzle diameter, and maximum displacement between nozzle and flapper effect on dynamic characteristics are analyzed. We have done simulations using the optimal design factors and simulink(Matlab) as a simulation tool, and verified the validity of our simulations by means of comparison our simulation results with an experimental results of another similar valve.

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