• 재활복지공학회논문지
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• 제5권1호
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• pp.1-10
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• 2011

본 연구에서는 공압 액추에이터를 이용하여 보다 안전하고 편리하게 사용자가 원하는 맞춤형 운동 프로그램을 선택할 수 있는 공압용 슬관절 운동시스템을 개발하였고, 재활운동 시 운동효과에 대한 유효성을 검증하고자 한다. 피험자는 평소 운동을 주 1회 이하로 실시하며 슬관절 신전과 굴곡에 이상이 없는 대학생 수준의 20대 남녀 10명을 대상으로 실시하였다. 실험방법은 기존의 유압식 슬관절 운동장비와 개발된 운동시스템을 이용하여 하루 12회씩 3세트의 슬관절 신전 및 굴곡운동을 실시하고, 주 3회 실시하며 실험은 총 4주간 반복되었다. 운동부하 프로그램은 유압식의 수동형 운동부하와 본 연구에서 개발된 시스템의 능동형 운동부하로 나누어 제공하였다. 운동부하 프로그램에 따른 실시간 근육활성 패턴과 운동 전 후 근육활성도를 비교함으로써 재활운동에 대한 운동효과를 검증하였다. 실험결과 수동형 운동부하보다 능동형 운동부하에 보다 높은 근육활성도를 이끌어 냈으며 운동 4주 후 더 큰 근력증진 효과를 나타냈다. 장비 중심의 운동부하 보다 사용자 중심의 운동부하가 더 효과적으로 근력을 증진할 수 있음을 알 수 있었다. 향후 재활환자나 노약자들에게 안전하고 효율적인 재활운동프로그램으로 활용 될 것이며 또한 재활장비에 적용되어 재활치료관련 종사자들에게 보다 쉽고 편리한 재활운동처방이 가능할 것이라 사료된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1991년도 추계학술대회 논문집
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• pp.171-179
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• 1991

This paper refers to the results of a study on the usefulness of simulation techniques based on both modeling and experiments of KICK DOWN pressure control circuit using an duty solenoid valve controlled by pulse width modulation for an automatic transmission. In this study, dynamic characteristics of solenoid valve plunger and first pressure are verified. Besides, this paper shows the design data for improvement of feeling in changing of gear by means of simulation according to varying the size of jet orifice and temperature of automatic transmission fluid, which are the important variables of the first pressure.

• 전자공학회논문지
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• 제51권10호
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• pp.228-234
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• 2014

건설 중장비의 경우 유압기기 및 전장 배선 등으로 인하여 내부의 배선이 매우 복잡한 구조를 가지고 있으며, 이러한 복잡한 배선으로 인하여 장비의 생산 및 유지 보수에 많은 시간이 소요되고 있어 원가 상승 요인으로 작용한다. 본 논문에서는 건설 중장비의 전장 배선을 간소화하기 위한 고신뢰성을 갖는 PLC(Power Line Communication)-CAN(Controller Area Network) 통신 모듈을 설계하고 구현한다.

• 한국정밀공학회지
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• 제20권4호
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• pp.136-142
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• 2003

The morphological analysis of wear debris can provide early a failure diagnosis in lubricated moving system. It can be effective to analyze operating conditions of oil-lubricated tribological system with shape characteristics of wear debris in a lubricant. But, in order to predict and recognize an operating condition of lubricated machine, it is needed to analyze and to identify shape characteristics of wear debris. Therefore, If the morphological characteristics of wear debris are recognized by computer image analysis using the neural network algorithm, it is possible to recognize operating condition of hydraulic driving members. In this study, wear debris in the lubricating oil are extracted by membrane filter (0.45 ${\mu}{\textrm}{m}$), and the quantitative values of shape parameters of wear debris are calculated by the digital image processing. This shape parameters are studied and identified by the artificial neural network algorithm. The result of study could be applied to prediction and to recognition of the operating condition of hydraulic driving members in lubricated machine systems.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.646-649
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• 2002

It can be effect on diagnosis of hydraulic machining system to analyze working conditions with shape characteristics of wear debris in a lubricated machine. But, in order to predict and estimate working conditions, it is need to analyze the shape characteristics of wear debris and to identify. Therefor, if shape characteristics of wear debris is identified by computer image analysis and the neural network, it is possible to find the cause and effect of moving condition. In this study, wear debris in the lubricant oil are extracted by membrane filter, and the quantitative value of shape characteristics of wear debris we calculated by the digital image processing. This morphological informations are studied and identified by the artificial neural network. The purpose of this study is In apply morphological characteristics of wear debris to prediction and estimation of working condition in hydraulic driving systems.

• 항공우주시스템공학회지
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• 제8권1호
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• pp.1-6
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• 2014

The conventional hydraulic circuits for electro-hydrostatic actuators equipped with a single-rod cylinder can oscillate under overrunning load conditions. In this paper the oscillation problem encountered in the conventional hydraulic circuits for EHAs is analyzed and it is shown by simulation results that this problem can be solved by employing a counter balance valve instead of a pilot-operated check valve generally used in the conventional hydraulic circuits.

• 유공압시스템학회논문집
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• 제1권4호
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• pp.15-21
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• 2004

High speed on-off electro-magnetic valves have been used for pressure control or flow control in automotive or construction machine servomechanisms. These systems require quicker valve switching speed to improve control preciseness. The authors designed and manufactured an electric valve driver with quick response characteristics by using 3 power source type valve driver concept. In experiments by using a hydraulic system incorporating the new valve driver, the new driver shortened the switching lag time from 5 ms to 1.3 ms. And also the new driver showed excellent position tracking control performances.

• 대한전기학회논문지:전력기술부문A
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• 제48권5호
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• pp.593-600
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• 1999

This paper suggests a suboptimal control scheme of an active suspension system with an asymmetric hydraulic cylinder. In this paper a quarter car model including a nonlinear actuator dynamics is used. A feedback linearization technique is applied to obtain a linear model. An LQ regulator is designed with the linear model to keep robustness against sprung mass variation. The gain of the LQ regulator which depends on the damping coefficient of the damper is calculated by using an RBF neural network for real time application. The improvement achieved with our design is illustrated through comparative simulations.

• 대한기계학회논문집
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• 제18권3호
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• pp.738-750
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• 1994

The load-sensing hydraulic system which was developed to improve energy efficiency of conventional hydraulic systems has its own properties. The instability of system responses, linearity of a servo valve, robustness for variation of external load, and dynamic interference between hydraulic motors are such properties which have much to do with control properties of the system. The load-sensing hydraulic system has instability tendancy because the load-sensing mechanism makes a positive feedback loop between the motor part and the pump part. A flow property of the servo valve can be said to be linear because the flow through the valve has nothing to do with a load pressure and the flow is strictly proportional to a valve opening which is adjusted by a valve command signal. The resultant control property can be said to be robust because the steady-state control performance is independent to the load actuated on the motor shaft. In the case when one pump simultaneously drives more than two hydraulic motors, the pump outlet pressure is determined by a hydraulic motor of the largest load pressure among all of the hydraulic motors, and, thus, the other motors are dominated by the largest load pressure. That is, the other motors can be said to be interfered by the motor of the largest load pressure.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1552-1564
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• 2002

Meter-in, meter-out and bleed-off circuits are widely utilized in order to adjust the speed of a hydraulic actuator by using a flow control valve and in order to regulate the pressure of a hydraulic volume by using a simple on-off valve. In these circuits, a relief valve serves either to maintain constant system pressure or to protect the system from over-pressure loading. The relief valve of a bleed-off circuit is the second case frequently undergoing on-off action during operation. It makes the analysis of the pressure control characteristics of the circuit highly difficult. In this paper, steady-state flow rate, pressure, heat loss and efficiency of the three circuits are reexamined and basic experiments far obtaining the characteristics of a pump and relief valve are conducted. Finally, simple empirical first-order dynamic models of decreasing and increasing pressure were separately proposed and verified by comparison with experiment. As the result, the basis for the theoretical analysis of the pressure control characteristics of a bleed-off circuit using a simple on-off valve is established.