• Title/Summary/Keyword: 압력커플링

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A Study of Energy Saving Hydraulic System by A Pressure Coupling Hydrostatic Transmission (압력커플링 정유압 변속기를 이용한 에너지 절감 유압시스템에 관한 연구)

  • Do, H.T.;Ahn, K.K.
    • Journal of Drive and Control
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    • v.9 no.1
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    • pp.10-17
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    • 2012
  • Nowadays, the demand of energy saving is increasing more and more while the natural resources have been exhausted. Besides, the emission gas caused by vehicles has been being a serious environment problem. Therefore, many studies have been carried out, especially focusing on braking energy regeneration, in order to save energy as well as reduce emission of mobile vehicles. In this paper, we propose a closed-loop hydrostatic transmission for braking energy regeneration with two configurations to reduce the energy consumption by recovering the braking energy. The effectiveness of the proposed system was verified by simulation. The simulation results indicated that the pressure coupling configuration gave better performance in comparison to flow coupling configuration about 40.8%, 61.7% and 53.8% reduction of fuel consumption in 10 mode, 10 mode modified profile and highway schedules, respectively.

Characteristics of Piezoelectric Sensor for Fluid Impact Pressure (유체 충격 압력 측정용 압전 센서 특징)

  • Choi, Young-Myung;Kim, Hyun-Yi;Park, Jun-Soo;Kwon, Sun-Hong;Kim, Dong-Jean
    • Journal of Ocean Engineering and Technology
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    • v.23 no.6
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    • pp.17-22
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    • 2009
  • This study presents an investigation of the characteristics of piezoelectric sensors whose main utilization is to measure impact pressure. The piezoelectric sensors were tested from several points of view. Their characteristics were investigated for repeatability, the effect of the diameter, temperature effect, water purity, flush mounting, and AC and DC coupling. Out of these, it was revealed that the temperature effect is very significant. The characteristics of the AC and DC coupling are also very important in understanding the time history of the impact pressure.

Coupling Effects of Stemming Materials in Blasting Hole by AUTODYN Analysis (발파공 내 전색물의 커플링 효과에 대한 AUTODYN 수치해석)

  • Baluch, Khaqan;Ko, Young Hun;Yang, Hyung-Sik
    • Explosives and Blasting
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    • v.35 no.3
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    • pp.9-14
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    • 2017
  • Coupling effects of the stemming materials for single borehole were studied by AUTODYN analysis and compared to understand the role of different stemming materials on transmitting the pressure from blasthole to the surrounding rocks. Five different material properties, air, sand, water, 10% and 20% gelatin were selected. Authors assumed that high pressure detected in borehole means better fragmentation. Simulations show that these coupling materials lead to different level of pressure in the blasting hole and 20% gelatin turns out to be highest among them. Results show that gelatin can be used as better coupling material than sand or water.

Study on Design of Coupling Bolt for Shaft in Power Plant (발전용 축계 결합용 커플링 볼트 설계에 관한 연구)

  • Jeong, HoSeung;Son, ChangWoo;Cho, JongRae;Kim, Tae Hyung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.5
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    • pp.707-713
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    • 2013
  • Coupling bolts have replaced conventional fitted bolts in applications where the operator's safety during assembly/disassembly is of concern or where the cost of process interruption is significant. Coupling bolts have been installed on rotating flange couplings in a wide range of marine and power applications worldwide. Their use has been approved by all leading international and national classification societies and regulatory bodies. A coupling bolt is a hydraulically tensioned fitted bolt that creates a stable and rigid link between coupling flanges and simplifies assembly and disassembly. We measure the bolt dimensions for reverse engineering and study the standard of assembly-load using a mechanical formula in order to localize a coupling bolt for a shaft in a power plant. We experimentally obtain the friction coefficient and confirm the condition of bolt sets through structure analysis. We show the variation of contact pressure for the shape parameter in order to consider the result when redesigning a bolt.

A Study on Temperature Field and Contact Pressure in Ventilated Disc-Pad Brake by 3D Thermo-mechanical Coupling Model (3차원 열-기계 커플링 모델에 의한 벤틸레이티드 디스크-패드 브레이크의 온도 분포와 접촉 압력에 관한 연구)

  • Hwang, Pyung;Seo, Hee-Chang;Wu, Xuan
    • Tribology and Lubricants
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    • v.25 no.6
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    • pp.421-426
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    • 2009
  • The brake system is important part of automobile safety system. The disc brake system is divided two parts: the rotating axisymmetrical disc and the stationary pads. During braking, the kinetic energy and potential energy of moving vehicle were converted into the thermal energy through frictional heat between the brake disc and the pads. The frictional heat, which is generated on the interface of the disc and pads, can cause high temperature during the braking process. The object of present work is to determine temperature and thermal stress, to compare to simulation results and experimental results in the disc by partial 3D model of ventilated disc brake with appropriate boundary conditions. In the simulation process, the mechanical loads were applied to the thermo-mechanical coupling analysis in order to simulate the process of heat produced by friction.

A Theoretical Study on the Fluid-Structure Interaction Due to the Pump in the Pressurized Water Reactor (원자로에서 펌프에 의해 야기되는 유체와 구조물 상호 작용에 대한 이론적 연구)

  • Lee, Kye-Bock;Jong Ryul park
    • Nuclear Engineering and Technology
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    • v.27 no.5
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    • pp.710-720
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    • 1995
  • The propagation of pump-induced pressure pulsation in a reactor is important because of the potential for vibration and resultant damage of reactor internals. A hydrodynamic model has been developed to obtain the pressure fluctuation due to the operation of pumps in the annulus(between the core support barrel and reactor vessel of a pressurized water reactor) including the coolant inlet pipe. The mathematical analysis is formulated in accordance with the linearized Navier-Stokes equation by assuming a compressible, inviscid flow. Two regions are considered separately and by coupling the solutions of the inlet pipe and the annulus, the inlet nozzle pressure(pressure at pipe and annulus interface) is to be calculated without assumptions. The geometric parameter effect on the pump-induced pressure pulsation is evaluated. Comparison of predicted and measured inlet nozzle pressure values for each forcing frequency shows good order of magnitude agreement.

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Measurement of Journal Bearing Friction Loss of Turbocharger in a Passenger Vehicle (승용차용 터보과급기의 저널 베어링 마찰 손실 측정)

  • Chung, in-Eun;Jeon, Se-Hun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.7
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    • pp.9-15
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    • 2018
  • The turbochargers, which are used widely in diesel and gasoline engines, are an effective device to reduce fuel consumption and emissions. On the other hand, turbo-lag is one of the main problems of a turbocharger. Bearing friction losses is a major cause of turbo lag and is particularly intense in the lower speed range of the engine. Current turbochargers are mostly equipped with floating bearings: two journal bearings and one thrust bearing. This study focused on the bearing friction at the lower speed range and the experimental equipment was established with a drive-motor, load-cell, magnetic coupling, and oil control system. Finally, the friction losses of turbochargers were measured considering the influence of the rotating speed from 30,000rpm to 90,000rpm, oil temperature from $50^{\circ}C$ to $100^{\circ}C$, and oil supply pressure of 3bar and 4bar. The friction power losses were increased exponentially to 1.6 when the turbocharger speed was increased. Friction torques decreased with increasing oil temperature and increased with increasing oil pressure. Therefore, the oil temperature and pressure must be maintained at appropriate levels.

A Study of Wind Energy Conversion System by a Secondary Control Hydrostatic Transmission (2차측 제어 정유압 변속기를 이용한 풍력발전시스템에 관한 연구)

  • Do, H.T.;Ahn, K.K.
    • Journal of Drive and Control
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    • v.10 no.1
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    • pp.21-28
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    • 2013
  • Wind energy has been more and more important and contributive in the energy utilization of the world. This paper proposed a novel method for Wind Energy Conversion System (WECS), in which a secondary control hydrostatic transmission (SC-HST) with two hydraulic accumulators, were employed for wind energy conversion system. This approach can absorb the excessive power of turbine, keep the generator from over-speed and maintain the speed of generator in low speed of turbine. A PID controller was designed for speed control to track a predefined speed. The simulation results indicated that the speed of the generator was ensured with the relative error less than 2%; and the efficiency of the proposed system was 70.4%.

Battle Damage Analysis of Aircraft Wing Fuel Tanks by Hydrodynamic Ram Effect (항공기 날개 연료탱크의 수압램 전투손상 해석연구)

  • Kim, Jong-Heon;Jeon, Seung-Mun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.4
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    • pp.17-24
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    • 2006
  • Hydrodynamic ram of aircraft fuel tanks is one of main ballistic battle damages of an aircraft and has great importance to airframe survivability design. Basic concept, physics and research history of hydrodynamic ram are investigated. The penetration and internal detonation of a simple fuel tank and ICW(Intermediate Complexity Wing) are analyzed by computational method. Structural rupture and fluid burst are analytically realized using general coupling and coupling surface interaction. The results such as fluid pressure, tank stress and displacement are shown and future research chances are suggested based on the study.

Study on Phase-Amplitude Characteristics in a Simplex Swirl Injector with Low Frequency Range (저주파 압력섭동 범위 내에서의 단일 스월 인젝터의 진폭-위상 특성 연구)

  • Khil, Tae-Ock;Chung, Yun-Jae;Yoon, Young-Bin
    • Journal of the Korean Society of Propulsion Engineers
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    • v.14 no.2
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    • pp.19-28
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    • 2010
  • Generally, combustion instability is generated by the mutual coupling between the heat release and the acoustic pressure in the combustor. On the occasion, the acoustic pressure generates the oscillation of the mass flow rate of propellant injected from injector, and this oscillation again affects combustion in the combustor. So, the dynamic characteristics of the injector have been studied to control combustion instability using injector itself in Russia from 1970's. In order to study injector dynamics, a mechanical pulsator for forced pressure pulsation is produced and the method to quantify the mass flow rate of the propellant that is oscillating at the exit of the injector is developed. With the pulsator and the method, pulsating values of the mass flow rate, pressure, liquid film thickness, and axial velocity generated at the exit of the simplex swirl injector are measured in real time. And phase-amplitude characteristics of each parameter are analyzed using these pulsating values acquired at the exit of the simplex swirl injector.