• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.863_864
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• 2009

Design and drive characteristics of SR drive for hydraulic pump system using passive converter is presented in this paper. In oder to get the high performance, a simple passive circuit is added in the front-end of a conventional asymmetric converter, which consists of three diodes and one capacitor. This passive converter has the high demagnetization voltage, to reduce the demagnetization time. Futhermore optimal turn-off angle for the proposed passive converter is proposed. According to motor speed and current, an optimal turn-off angle can be achieved by look-up table to reduce torque ripple. The characteristic of proposed hydraulic pump system using passive converter is verified by simulation and experimental results.

• 한국해양공학회지
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• 제29권5호
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• pp.380-385
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• 2015

In the development of an underwater construction robot, the reliability of the operating system is the most important issue because of its huge maintenance cost, especially in a deep sea application. In this paper, we propose a new redundant architectural design for the hydraulic control system of an underwater construction robot. The proposed architecture consists of dual independent modular redundancy management systems linked with a commercial profibus network. A cold standby redundancy management system consisting of a preprocessing switch circuit is applied to the signal network, and a hot standby redundancy management system is adapted to utilize two main controllers.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.150-158
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• 2002

Through experimental works, the damping force vibration problem was investigated, which results from valve and surge pressure in the oil return line of the hydraulic circuit of an active suspension system in a passenger cu. Experiments were carried out under passive system, where an orifice valve was closed and non-active system, where an orifice valve was opened, using a pressure control valve controlled by solenoid. The effects of parameters of the valve overlap and accumulator on smoothing surge pressure was elucidated. It was proved that the apparent variation of damping force due to the overlap amount of pressure control valve is the most important factor to control the damping force variation. The procedure of the experimental works shows the development process of a proportional pressure control valve in the hydraulics system of an active suspension system of passenger car.

• 한국기계연구소 소보
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• 통권20호
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• pp.27-32
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• 1990

A counter balance valve is used as one part of hydraulic motor brake system. The function of this valve is to protect over-run or free falling of inertia load. But occasionally the brake system with counter balance valve makes some undesirable problems such as pressure surges or vibrations. In this study, for the purpose of easy estimation about dynamic chrcteristics of hydraulic system including counter balance valve, precise formulation describing fluid dynamics and valve dynamics under various boundary conditions were made. dynamic caracteristics were analysed by numerical intergration using Runge-Kutta method, because the equations in this circuit with counter balance valve contain various nonlinear terms. So the analyzing method developed in this study enabled very easy estimating the relation between the performance of counter balance valve and various physical parameters related to the valve.

• 한국자기학회지
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• 제26권2호
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• pp.55-61
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• 2016

본 논문에서는 설계변수 변화에 따른 특성을 빠른 시간 내에 파악할 수 있는 등가자기회로법(equivalent magnetic circuit method)을 활용하여 콜레노이드(colenoid) 타입의 선형 액츄에이터 설계 알고리즘을 제시하였다. 우선 선형 액츄에이터의 중요치수가 결정되면 등가자기회로법에 의해 슬롯 폭 비율 및 인가전류에 따른 클램핑력으로 파라미터 맵(parameter map)을 완성하고 이를 활용하여 효율적인 슬롯 폭 비율을 결정하였다. 또한 최대 클램핑력(clamping force)을 얻기 위해 극 폭 조절 알고리즘을 수행하여 최적의 극 폭 치수를 선정하였으며 이를 바탕으로 인가전류에 따른 클램핑력을 계산하여 40 kN 이상 출력하기 위한 최적의 극 수, 극 폭 치수 및 인가전류를 결정하였다. 제안된 설계 알고리즘은 최적설계 방법인 반응표면법(response surface method)과 비교하여 제안한 설계 알고리즘의 타당성을 검증하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.301-302
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• 2009

• International Journal of Fluid Machinery and Systems
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• 제2권4호
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• pp.324-333
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• 2009

This paper presents a numerical simulation study of the transient behavior of a $2{\times}340MW$ pump-turbine power plant, where the results show an unstable behavior at runaway. First, the modeling of hydraulic components based on equivalent schemes is presented. Then, the 2 pump-turbine test case is presented. The transient behavior of the power plant is simulated for a case of emergency shutdown with servomotor failure on Unit 1. Unstable operation at runaway with a period of 15 seconds is properly simulated using a 1-dimensional approach. The simulation results points out a switch after 200 seconds of the unstable behavior between a period of oscillations initially of 15 seconds to a period of oscillation of 2.16 seconds corresponding to the hydraulic circuit first natural period. The pressure fluctuations related to both the rigid and elastic water column mode are presented for oscillation mode characterization. This phenomenon is described as a switch between a rigid and an elastic water column oscillation mode. The influence of the rotating inertia on the switch phenomenon is investigated through a parametric study.

• 드라이브 ㆍ 컨트롤
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• 제11권4호
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• pp.8-14
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• 2014

The transmission control method of a small forklift is classified into a pilot control method and a direct control method. In the pilot control method, the complex hydraulic circuit consists of many components, making the production process too costly and time consuming. The direct control method contains fewer components that can be configured to simple hydraulic circuits. As another advantage, the input profile easily changes the shift sensitivity of the transmission. Therefore, this research considers the characteristics of the direct control method in the development of hydraulic system design. This paper will present a simulation of the direct control transmission using AMESim. First, modeling of the direct control method is obtained and simulated with real parameters. The simulation results then are carried out and compared with the experimental results to verify and analyze the characteristics of the direct control method.

• 드라이브 ㆍ 컨트롤
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• 제19권1호
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• pp.26-33
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• 2022

This study dealt with a self-propelled spinach harvester, which is capable of carrying out sequential harvesting work. This study aimed to find the cause of the harvester's occasional performance deterioration, which occurs in the process of simplifying the hydraulic circuit, using a multi-domain analysis model. The study was carried out in the following manner. First, a hydraulic system analysis model, which combines linear motion, rotary motion, hydrodynamic behavior, and an electrical signal, was developed through SimulationX software, specialized in multi-domain analysis. Second, a scenario for single behavior and coupled behavior was set out on an actuator basis. Third, the flow rate of the hydraulic system, which is not required for the movement of the actuator, was quantitatively analyzed. The results showed that a change in oil temperature was the cause of the harvester's occasional performance deterioration. And the higher the oil temperature, the more serious the performance deterioration, especially as the number of actuators operated simultaneously was small.

• 한국소음진동공학회논문집
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• 제27권2호
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• pp.168-174
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• 2017

In this work, a piezostack single-stage valve (PSSV) system is proposed and its control performance is experimentally evaluated at high temperature up to $150^{\circ}C$. In order to achieve this goal, a PSSV system is designed and operating principle and mechanical dimensions are discussed. A displacement amplifier and an adjust bolt are used to generate target displacement and to compensate thermal expansion. Then, an experimental apparatus is constructed to evaluate control performance of the PSSV system. The experimental apparatus consists of a heat chamber, a hydraulic circuit, a pneumatic circuit, pneumatic-hydraulic cylinders, thermal insulator, electronic devices, sensors, data acquisition (DAQ) board and a voltage amplifier. The flow rate and displacement control performance of the valve system are evaluated via experiment. The experimental results are evaluated and discussed at different temperatures and frequencies showing the controlled flow rate and spool displacement.