• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.164-172
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• 2020

The fuel oil/heat exchanger installed in military aircraft is a device that cools the lubricant oil supplied to other devices, such as an AMAD, and a hydraulic pump using the low temperature of the fuel is cracked at the AMAD lubricant inlet port. If a crack in the heat exchanger occurs, the lubricant oil supplied to other equipment is not cooled. Therefore, the flight can no longer be performed. In this study, non-destructive inspection and microscopic examination of the fracture surface of the oil port were performed to analyze the crack tendency. The oil pipe connected to the oil port is a titanium pipe, which is fastened with over torque and has been identified as the leading cause of heat exchanger oil port cracks. In addition, it was verified as the main reason for cracking by finite element analysis. The material and diameter of the pipe were changed to improve this defect, and the applied torque was adjusted. In addition, the bending value of the pipe was adjusted to minimize the fatigue accumulation due to pulsating pressure. As a result, no cracks occurred on the heat exchanger via the ground test after the installation of an improved pipe under the same conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.614-617
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• 1995

The unbalance heavy-load elevation driving systems are composed of rotating link-mechanism and hydraulic cylinder which actuates elevation and compensates the static unbalance moment of supporting mechanism. Control and compensation of gun driving is very difficult because these mechanism imply highly nonlinearities due to hydraulic fluid characteristics and mechanical rotation of link-mechanism. In this study, through the analysis of manufactured link-mechanism, the optimal link-mechanism design of the elevating system is suggested. Also to estimate the control performance of the unbalance heavy-load elevation servo-control driving system, modeling and simulation of the system are carried out. To prove the reliability of performance estimation program,simulation results are compared with the experimental results. Both results are similar, therefore this program will be helpful to study the control performance improvement of the system.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.9
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• pp.15-21
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• 1997

In this paper, a self-activated cable spooling system for seaborne winch is developed . The system consists of a hydraulic servo driving unit and a cable position measurement mechanism. To realize the cable spooling system, it is carried out the mathematical modelling of the system and designed the proportional controller through the system aalysis and the simulation. The cable spooling system is tested and evaluated to validate the performance of the controller. The test results shows a good traceability of the cable spooling system under disturbance of cable tension.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.4
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• pp.335-341
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• 2010

The electric braking system obtains its braking force by a motor instead of the hydraulic brake which has been used in conventional automobile systems. Electric braking system is consisted of fewer numbers of components than hydraulic braking system, and it has effects of improved response and reduced braking distance for the ABS(Anti-lock Brake System) and ESC(Electronic Stability Control). This paper presents the BLAC motor drive system for Electro-Magnetic Brake(EMB). Proposed control system consists of the power converter for driving a motor and the digital control system for speed control, and the vector control is applied for fast torque response. It is verified through the simulation using Matlab/Simulink and experiment that the proposed BLAC drive system can be applied to EMB.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.10
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• pp.738-746
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• 2019

Instead of hydraulic actuation systems, an electromechanical actuation system is more efficient in terms of weight, cost, and test evaluation in the thrust vector control of the 7-ton gimbal engine used in the Korea Space Launch Vehicle-II(KSLV-II) $3^{rd}$ stage. The electromechanical actuator is a kind of servo actuator with position feedback and uses a BLDC motor that can operate at high vacuum. In the case of the gimballed rocket engine, a synthetic resonance phenomenon may occur due to a combination of a vibration mode of the actuator itself, a bending mode of the launcher structure, and an inertial load of the gimbals engine. When the synthetic resonance occurs, the control of the rocket attitude becomes unstable. Therefore, the requirements for the stiffness have been applied in consideration of the gimbal engine characteristics, the support structure, and the actuating system. For the 7-ton gimbal engine of the KSLV-II $3^{rd}$ stage, the stiffness requirement of the actuation system is $3.94{\times}10^7N/m$, and the direct drive type electromechanical actuator is designed to satisfy this requirement. In this paper, an equivalent stiffness analysis model of a direct drive electromechanical actuator designed based on the stiffness requirements is proposed and verified by experimental results.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2003.02a
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• pp.278-283
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• 2003

트랙터 작업은 일반적으로 부하의 변동이 크기 때문에 잦은 변속이 요구되며, 견인 또는 다양한 작업기의 구동 등 작업 조건에 따라 적합한 작업 속도를 얻기 위한 많은 변속 단수가 요구된다. 이러한 특성 때문에 트랙터의 변속기는 큰 견인 부하에서도 정지하지 않고 원하는 속도로 원활하게 변속할 수 있어야 하며 동시에 동력 손실을 최소화할 수 있어야 한다 따라서, 트랙터 변속 장치는 작업 능률과 전동 효율을 동시에 고려할 경우, 작업 능률이 놀은 유압 변속과 동력 전달 효율이 놀은 기계식 동력 전달을 조합한 파워시프트 변속이 가장 우수한 것으로 판단된다. (중략)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.254-260
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• 1995

본 연구에서는 제어 알고리듬 적용면에서 가속도 계측이 보다 용이한 점을 고려하여 가속도가 포함된 가속도-속도-변위 되먹임 제어 알고리듬을 개발하고, 이를 유압식 능동 질량구동장치에 적용하여 능동제어시스템의 성능을 실증적으로 검토한다. 이 때 능동제어시스템의 구성요소들의 동특성을 시스템 모델링에 포함하여 제어력을 산정함으로써 시간 지연의 영향을 효과적으로 보상하는 방안을 제시한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.919-928
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• 2010

Four patterns for width adjustment were studied with an aim to increase the width-adjustment speed in continuous casting. The main goals are to minimize the actuating force of a WAM actuator, to develop a deformation analysis model of a solidified shell in the mold, and to induce the main limit factor for the speedup of width adjustment. On the basis of the width-adjustment experiment, the notable features of four patterns types were considered, and we compared the corresponding actuating forces. For comparing the driving forces of the patterns, during the experiment, the same casting speed was maintained for each pattern. To optimize the parameter of the deformation analysis model of the solidified shell, the experiment results were applied to them. To speed up width adjustment and to reduce the driving force, we controlled the pattern parameters. The most effective pattern was the fast-mode pattern, and the taper was the main parameter that helped reduce the driving forces during the motion of the actuator.

• Transactions of The Korea Fluid Power Systems Society
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• v.7 no.2
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• pp.19-26
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• 2010

The typical trunk lid system for vehicle is composed of a hinge having 4-bar link and gas lifter. Here, the energy regenerative brake of hydraulic driven systems is applied to the tail gate system for vehicle and removed the gas lifter. The new tail gate system is composed of a hydraulic pump by electric motor, a hydraulic motor, four check valves, an accumulator, a relief valve and a directional control valve. The dynamic characteristics of the hydraulic motor system, such as the surge pressure and response time, are investigated in both brake action and acceleration action. The capacity selection method of accumulator by mathematical model is based upon trial and error approach and computer simulation by AMEsim software is carried out.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.127-133
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• 2001

In this study, the effect of the factors of a hydraulic modulator of ASMS was analysed. The modeling of ASMS was presented and the equation of ASMS was derived from the modeling. With this background, GUI analysis tool was developed. After the verification of the reasonability of simulation, the response of a hydraulic modulator is investigated through simulation of modeling. With this simulation, each behavior was predicted with changing the various parameters and determined the influenced factors to apply the designing process.