http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
On the Optimal Shape of Gear Teeth End Gaps for Hydraulic Gear Pumps and Motors
Heon Sul Jeong,Lili Feng,Seok-Hyung Oh 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.9
In order to improve the efficiency of hydraulic gear pumps or motors especially for high operating pressure or temperature, power losses due to viscous friction acting on and leak flow through gear teeth end-gaps are considered in this paper. Formulas of the viscous friction and leak flow through a gap are derived and then the optimal gaps minimizing the power loss for pumps and motors with uniform heights of gaps are analyzed first. And the effect of the shapes of gaps with unequal heights on the power loss are discussed by simulation study. Considering that the outer shell facing gear teeth may expand due to high internal pressure or thermal stress, the results drawn in this paper can be used for the design of high efficiency pumps and motors.
A Novel Performance Model Given by the Physical Dimensions of Hydraulic Axial Piston Motors
Heon-Sul Jeong 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.1
Since Wilson (1948) had firstly developed steady-state flow rate and moment loss model for hydraulic piston machines, several authors tried to make precise performance models. However, Huhtala (1997) discussed the strength and weakness of some existing models comparing with measurement data and concluded unfortunately that any model is not accurate enough for wide operating ranges. For a hydraulic axial piston motor of swash plate design with rotating cylinder, new performance formula is derived in this paper through theoretical study on leakages and friction losses of three facing gaps and other non-negligible losses. And efficiency surface of an example motor is estimated and extension of the formula for hydraulic pumps is discussed. A novel feature of the derived model is that all coefficients are given by the physical dimensions of a motor, hence allowing calculation and analysis of the performance of a motor in mind.
On the Instantaneous and Average Piston Friction of Swash Plate Type Hydraulic Axial Piston Machines
Heon-Sul Jeong,Hyoung-Eui Kim 대한기계학회 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.10
Piston friction is one of the important but complicated sources of energy loss of a hydraulic axial piston machine. In this paper, two formulas are derived for estimating instantaneous piston friction force and average piston friction moment loss. The derived formula can be applicable for piston guides with or without bushing as well as for axial piston machines of motoring and pumping operations. Through the formula derivation, a typical curve shape of friction force found from several experimental measurements during one revolution of a machine is clearly explained in this paper that it is mainly due to the equivalent friction coefficient dependent on its angular position. Stribeck curve effect can easily be incorporated into the formula by replacing outer and inner friction coefficients at both edges of a piston with the coefficient given by Manring (1999) considering mixed/boundary lubrication effects. Novel feature of the derived formula is that it is represented only by physical dimensions of a machine, hence it allows to estimate the piston friction force and loss moment of a machine without hardworking experimental test.
Sliding Mode Trim and Attitude Control of a 2-DOF Rigid-Rotor Helicopter Model
Heon-Sul Jeong,Se-Myong Chang,Jin-Sung Park 한국항공우주학회 2005 International Journal of Aeronautical and Space Sc Vol.6 No.2
An experimental control system is proposed for the attitude control of a simplified 2-DOF helicopter model. The main rotor is a rigid one, and the fuselage is simply supported by a fixed hinge point where the longitudinal motion is decoupled from the lateral one since the translations and the rolling rotation are completely removed. The yaw trim of the helicopter is performed with a tail rotor, by which the azimuthal attitude can be adjusted on the rotatable post in the yaw direction. The robust sliding mode control tracking a given attitude angle is proposed based on the flight dynamics. A pitch damper is inserted for the control of pitching angle while the compensator to reaction torque is used for the control of azimuth angle. Several parameters of the system are selected through experiments. The results shows that the proposed control method effectively counteracts nonlinear perturbations such as main rotor disturbance, undesirable chattering, and high frequency dynamics.
건설기계용 가변용량형 피스톤 펌프 레귤레이터의 EPPR 밸브를 이용한 선형, 비선형 압력제어 모델링 비교분석
정헌술(Heon-Sul Jeong),장진현(Jin-Hyeon Jang) 유공압건설기계학회 2016 유공압건설기계학회 학술대회논문집 Vol.2016 No.11
Normally hydraulic piston pumps are controlled by a mechanical type regulator consisted of springs and valves, but construction of the mechanical regulator is very complicated, Hence nowadays electro-hydraulic regulators are emerging to overcome poor control performance, difficult adjustment work and limited control functionality. This paper focuses on the pressure control of a electro-hydraulic type regulator using EPPR valve for a variable displacement swash plate type piston pump. First of all, PI Pressure controller is constructed and Simulink and AMESim simulation models for those mathematical models are developed. Comparison results of the hydraulic pump characteristics response and pressure control performance depending on the complexity of the simulation models are discussed and some conclusions are given.
Sliding Mode Trim and Attitude Control of a 2-00F Rigid-Rotor Helicopter Model
Jeong, Heon-Sul,Chang, Se-Myong,Park, Jin-Sung The Korean Society for Aeronautical and Space Scie 2005 International Journal of Aeronautical and Space Sc Vol.6 No.2
An experimental control system is proposed for the attitude control of a simplified 2-DOF helicopter model. The main rotor is a rigid one, and the fuselage is simply supported by a fixed hinge point where the longitudinal motion is decoupled from the lateral one since the translations and the rolling rotation are completely removed. The yaw trim of the helicopter is performed with a tail rotor, by which the azimuthal attitude can be adjusted on the rotatable post in the yaw direction. The robust sliding mode control tracking a given attitude angle is proposed based on the flight dynamics. A pitch damper is inserted for the control of pitching angle while the compensator to reaction torque is used for the control of azimuth angle. Several parameters of the system are selected through experiments. The results shows that the proposed control method effectively counteracts nonlinear perturbations such as main rotor disturbance, undesirable chattering, and high frequency dynamics.
정헌술(Heon-sul Jeong),남지우(Ji-woo Nam),임효준(Hyo-joon Lim),정승욱(Seung-wook Jung),한성민(Sung-min Han) 유공압건설기계학회 2010 유공압건설기계학회 학술대회논문집 Vol.2010 No.6
Because of the increasing demand on the high precision and high response of a machinery, electronic control valves are widely adopted at various application fields. This paper studies on the static characteristic of a first-stage proportional pressure control valve. At first an experimental apparatus including hyd. pump variable speed inverter, pressure and data aquisition system was setted up with the experimental apparatus, various tests such as P-Q-W test, hyd, pump, dynamic, static, frequency response test of the proportional valve was carride out and the results are discussed.