• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.13 no.6
• /
• pp.134-138
• /
• 2014

Power packs can change energy to hydraulic energy generated by an engine as a tool for use with civil engineering construction equipment. This paper determines which type of power pack meets the standards of construction machinery. A power pack was formulated as a three-dimensional model by using the software CATIA. A modal analysis was conducted using ANSYS Workbench, and the resonance was checked. Next, a harmonic analysis was conducted. The analytical results show that the dynamic stability of the power pack is assured.

• Journal of Drive and Control
• /
• v.2 no.2
• /
• pp.35-42
• /
• 2005

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.8
• /
• pp.1565-1576
• /
• 2002

By way of driving a 2-way on/off solenoid hydraulic valve with a pulse width modulation (PWM) signal, control of the pressure in a certain volume is frequently used in various applications. However, the pressure built-up according to the duty ratio and carrier frequency of the PWM signal is not so well understood. In order to clarify the characteristics of 2-way valve hydraulic pressure control systems, in this paper two formula fur the mean and ripple of the load pressure were derived through theoretical analysis. And the accuracy of the derived formula were verified by comparison with the experimental test result. Generally 2-way valve systems are constructed as a bleed-off circuit, while 3-way valves are used as a control element in a meter-in circuit pressure control system. In a bleed-off circuit, the system supply pressure from a hydraulic power pack does not remain constant, but changes according to their external load. In turn, the relief valve in the hydraulic power pack reacts accordingly showing complicated dynamic behavior, which makes an analytical study difficult. In order to resolve the problem, simple but accurate empirical dynamic models fer a bleed-off system were used in the course of formula derivation. As the result, selection criteria for two major control parameters of the driving signal is established and the basic strategy to suppress the unnecessary pressure fluctuation can be provided for a hydraulic pressure control system using a 2-way on/off solenoid valve.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.1
• /
• pp.112-119
• /
• 2009

An automatic transmission of construction equipment is controlled by hydraulic and electronic system for doing in various functions like as shifting and operation. The shifting is operated by the engaged and disengaged clutch motion from hydraulic power. On the shifting process, suitable pressure control to the clutch is required for smooth shifting. Hydraulic control system in the automatic transmission is divided by the pilot control type and the direct control type greatly. The direct control type has an advantage than the pilot control type. Because the structure is simple, the design and the manufacture are having less troubles and the system can be maximized precision pressure control. However, the excellent performance proportional control valve should be used to achieve proper control-ability. In this study, the dynamic analysis model composing the automatic transmission and hydraulic system for forklift truck is presented to simulate the characteristics of hydraulic system about the direct control type. That model is verified the validity compared the results of the testing examination. Parameters of input signal are analyzed to reduce the output torque according to input control signal is affected in shifting characteristic.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.94-98
• /
• 2017

Research for developing 9 tonf-class staged combustion cycle engine which is high performance upper stage engine has been conducted. Technical demonstration model of the staged combustion cycle engine was installed in combustion test facility of Naro space center. Combustion tests of Power-pack which consists of pre-burner and turbopump without main combustion chamber and combustion tests of engine have been conducted. The vacuuming process of hydraulic lines is introduced and the characteristics of turbopump and hydraulic lines of engine combustion test are described in this paper.

• Journal of the Korean Society of Industry Convergence
• /
• v.26 no.1
• /
• pp.175-181
• /
• 2023

In offshore plants, various equipments including cranes and davits are used for safety management. Hydraulic cylinder type actuators are mainly used for luffing operations such as cranes and davits. However, in the case of a cylinder using hydraulic pressure, a separate power pack is required to supply hydraulic pressure. When used for a long time, maintenance costs such as sticking of hydraulic valves, contamination of hydraulic oil and deterioration of hydraulic hoses occur. In addition, a lot of hydraulic oil is used in the handling of cranes and davits, which causes marine pollution due to management problems. As a result, as interest in marine pollution prevention has increased recently, interest in actuators that do not use hydraulic pressure is also increasing. Therefore, in this study, we intend to develop a davit with an electric cylinder type actuator that uses electricity rather than hydraulic pressure by the SOLAS regulation. In other words, the conceptual design of the davit driven through the linear motion of the ball screw using electricity is performed, and the structural safety of the drive is also reviewed so that it can be utilized in the industrial field.

• Journal of the Korea Society for Simulation
• /
• v.28 no.2
• /
• pp.35-48
• /
• 2019

Domestic hydraulic drifters till now have been developed by benchmarking products from overseas leading companies. However, they do not have excellent impact performance as they are not suitable for characteristics (large flow rate and low pressure) of Korean hydraulic drill power pack, and therefore, research on the optimum design has not made much headway. This study performs multi-objective function optimization for hydraulic drifters whose capacity has been redesigned to deal with the large flow rate, and also with the help of this function, it aims to improve impact power and reduce supply and surge pressure. A summary of the research study is as follows: First, we set goals for improving impact power, supply pressure, and surge pressure, and then perform multi-objective function optimization on them. After that, we secure the reliability of the optimized analytical model by comparing the test results of the prototype built by the optimized design with the analysis results of the analytical model. This study used SimulationX, that is the hydraulic system analysis software, and EasyDesign, which is a multi-objective function optimization program. Through this research, we have achieved the results that satisfy the goal of developing high power drifters suitable for Korean type hydraulic drills.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.23 no.3
• /
• pp.9-17
• /
• 2019

Variable guide vanes(VGVs) that consist of link mechanisms and an actuator system are required for an aircraft gas turbine engine to adjust the incidence angle of stator vanes. In this study, we developed a VGV actuator system for three-stage VGVs with two hydraulic actuators. The requirements for the actuator system were derived by analyzing the link mechanisms and air loads, and a hydraulic power-pack was developed based on these requirements. Through a load test using the actuator test-rig and the application of synchronizing control logic with proper control gains, the actuator system could be developed and verified.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2009.09a
• /
• pp.71-79
• /
• 2009

The world-wide ship construction market is forecast that the considerable portion of shipbuilding and oceanic plant industry will be transferred consequently in China after 5 or 10 years. This point of view where the Korean ship construction industry seizes the initiative from the world-wide ship construction/oceanic field, we must cultivate technical power of base technology, and focus our interests on the development of core parts. In this study, our proprietary remotely operated valve actuator system with power line technology was developed to enhance the installation and commissioning process by our own technology. This paper describes the new design and functions of the remotely operated valve system for shipbuilding and offshore market especially for FPSO.