• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.486-489
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• 2003

To reduce lateral force of traditional plunger type piston in the swash plate type hydraulic piston pumps and motors, we have proposed rod type piston with ball joint on both ends. We have studied the theoretical reaction force on two types of piston moving in the cylinder block bore. and made an experiment for the resistance force measurement on a reciprocating motion of plunger and rod type piston, changing the test condition such as swash plate angel and supply oil pressure and so on. As a result. a rod type piston has more smaller resistance force, about 29%. than a plunger type one.

• 한국자동차공학회논문집
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• 제10권4호
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• pp.166-174
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• 2002

Power steering systems far automobile are becoming ever more popular because they reduce steering efforts of the drivers, especially during parking lot maneuver. In this paper, the controller of the motor driven hydraulic power steering(MDHPS) has been designed and developed. This system uses a power source of DC motor instead of engine power source for power steering drive oil pump. The developed MDHPS system is accomplished a highly sensitive power steering resulted from electronic control under variable driving condition. Furthermore, this system is more improvement than type of engine driving far fuel economy.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권7호
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• pp.369-373
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• 2006

In this paper, an optimal method for determining design parameters of a Switched Reluctance Motor is researched. The dominant design parameters are stator and rotor pole arc and switching on and off angle. The parameters affecting performance are examined and selected using evolutionary computations and commercial CAD program. The simulated design method is compared with conventional procedure.

• Tribology and Lubricants
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• 제30권3호
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• pp.183-188
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• 2014

In this paper, we present our analysis of tribological failure examples for an anti-lock brake system(ABS) in a car. The study range of this paper is to improve the quality of ABS system by analyzing with sensor, computer, actuator and oil lines. In the first example, the brake leak from hydraulic supply line in a caliper on the rear left side of the ABS hydraulic modulator. This produces the sponge phenomenon, where the car does not brake even when the driver operates the brake pedal. The hydraulic unit operating ABS is actuator that play role regulating drive condition according with the oil pressure supplied with wheel of a car. In the second example, the service man does not completely tighten the fixed bolt after repairing the car. This causes the ABS warning lamp to light up as the ABS wheel speed sensor cannot detect whether the ABS has been activated. In the third example, the ABS electronic control unit is separated from the soldered part of the inner circuit board. Consequently, the ABS fails in control because the ABS motor pump receives no-signal for the hydraulic unit. The wheel speed sensor has to large durability because of giving signal of acting condition to computer by detected the acceleration and deceleration of wheel of a car. In the fourth example, the ABS warning lamp lights up of when cracks propagate in the circuit board soldering part. The circuit of this computer is very important part for input and output the operating signal of system. Such failures can aggravate the durability of the ABS. Thus, the ABS needs to be optimized to eliminate malfunction phenomenon.

• 한국산업융합학회 논문집
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• 제25권3호
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• pp.379-386
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• 2022

The goal of this research is to verify a performance test system for a low speed, high torque, and harsh reducer at low cost. The reducer rotates a cooling fan with a diameter of 10 meters, in a high temperature (50℃) cooling tower in a geothermal power plant. It requires about 500 kgf·m torque and 47.75 kW power to rotate the fan at a maximum power condition. An expensive dynamometer is commonly used for performance test of a motor or a reducer. In this paper, a low cost system is developed using a hydraulic pump as a load unit to generate torque instead of a dynamometer. We accurately calculated the required power, the flow meter, and the pressure of the pump, and selected to design and optimize the system at minimal cost. The system also applied another reverse reducer and a gearbox to increase the rotational speed and to reduce the torque from the low speed and high torque target reducer. This allows low-cost systems to be built using inexpensive components. The developed system was able to successfully measure the high torque and the low rotational speed of the target reducer at high temperature.

• 한국자동차공학회논문집
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• 제25권1호
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• pp.103-110
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• 2017

Most commercial vehicles have adopted the hydraulic power steering system. To reduce fuel consumption and to improve steering controllability, a hybrid electric power steering system is being developed for commercial vehicles. In this study, the HILS (Hardware In the Loop Simulation) system equipped with a commercial vehicle hybrid electric power steering system was developed and the vehicle dynamic performance of a truck with the steering system was evaluated. The hybrid electric power steering system is composed of the EHPS motor pump, column mounted EPS system, and ball nut steering gear box for heavy commercial vehicles. The accuracy of vehicle models equipped with the HILS system was verified with comparisons between the simulation results and field test results. The road reaction forces of the steering system were generated from the vehicle model and verified using field test results. Step steering tests using the verified HILS system were carried out and the performance of a newly developed commercial vehicle hybrid electric power steering system was evaluated.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2006년도 학술발표대회 논문집
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• pp.116-125
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• 2006

Piston assemblies, which are key components of hydraulic high pressure pumps & motors, are major failure products operating at high pressure and high speed, and the main failure mode is wearout of the shoe surface. To predict the actual life of piston assemblies. we require to find out the most sensitive parameters and establish related empirical formula. In this study, we analyzed the life of piston and shoe assemblies in accordance with variation of speed, pressure, and temperature to reduce the life test time, then analyzed the result of combined accelerated life test which is applied by high speed, speed pressure, and high temperature simultaneously, and finally developed combined accelerated life test model.

• 대한기계학회논문집A
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• 제39권2호
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• pp.211-217
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• 2015

환경 문제 및 화석연료 고갈에 대한 관심으로 인하여 배기가스에 대한 규제는 나날이 엄격해지고 있으며 높은 연비에 대한 수요는 지속적으로 증가하고 있다. 이러한 시대적 요구를 뒷받침하기 위하여 저배기-고연비가 특징인 하이브리드 굴삭기가 현실적인 대안으로서 각광받고 있으며 지속적으로 연구되고 있다. 본 연구에서는 선회 구동 전동기, 엔진보조 전동기, 울트라 캐패시터, 전력변환장치를 중형 굴삭기에 탑재한 복합형 하이브리드 굴삭기를 개발하였으며, 일반적인 복합형 하이브리드 굴삭기의 연비개선요소(선회 구동 에너지 회생, 엔진 작동 속도 변경)외에 추가적으로 적용된 연비개선 방법론들에 대하여 다루고 있다. 본 방법론들을 적용함으로써 연비와 운전 조작성을 동시에 개선할 수 있었다.

• 대한기계학회논문집
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• 제17권8호
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• pp.2023-2032
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• 1993

This study suggests a new type shaft generating system driven by hydrostatic transmission suitable for small size vessels. Since the shaft generating system is affected ceaselessly by disturbances such as speed variation in pump driving speed and variation in external load, a robust servo control must be implemented to obtain stable electric power with constant frequency. Thus, in this study, a digital robust servo control algorithm is applied to the controller design. By the experiment and the numerical computation, the frequency variation characteristics of the generating system under various disturbances are investigated. Conclusively, it is said that the shaft generating system proposed in this study shows excellent control performances.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1033-1034
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• 2011

공작기계에 유압동력을 공급하는 유압동력발생장치의 신뢰성은 공작기계 전체의 신뢰성과 밀접한 관계를 가진다. 전기모터에 의해 유량을 직접제어하는 유압펌프의 시제품에 대한 신뢰성을 평가하기 위해서 성능시험, 내환경시험, 그리고 수명내구시험을 실시할 필요가 있다. 본 연구에서는 2단계 품질기능 전개를 통해 전기모터에 의한 직접유량 제어방식 유압펌프의 신뢰성평가 시험항목을 결정하였다. 시험항목에는 전기모터에 대한 항목, 유압펌프에 대한 항목, 하우징 및 냉각시스템에 대한 항목이 포함되어 있다. 신뢰성평가 시험 항목 중, 가장 큰 비중을 차지하는 수명내구시험에 대해 무고장수명시험을 산출하고, 시험소요시간 단축을 위한 가속모델을 제안하고, 실제 구동 조건을 적용하여 가속수명시험시간을 산출하였다.