유압식 엘리베이터의 제어특성에 관한 연구

염만오,Yum, Man-Oh 한국기계가공학회 2003 한국기계가공학회지 Vol.2 No.3

In this study an elevator plant model is made with an electro-hydraulic servo valve and a single rod cylinder. A PID controller, a velocity feedback PID controller and a MRAC controller ate designed. Experimental apparatus including an elevator plant model and these controllers are constructed. In case of experiment, external load which is made with a hydraulic cylinder and a pressure control valve burdens varying load to the elevator plant model being driven. With experiment, the control performances of three proposed control methods are compared.

사판식 유압모터의 특성실험 (I)

염만오,윤일로,Yum, Man-Oh,Yoon, Il-Ro 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.4

The purpose of this study is to construct a testing equipment with which several characteristics of the domestically developed swashplate type axial piston motor can be tested and to develop a software with which the data from experiment can be stored and can be applied. The results of the study are as follows; 1) The leakage flow and the torque of the motor being stopped is propotional to supply pressure and their relation can be showed by linear equations. 2) The motor movement is not smooth below 50 rpm but it moves smoothly up 170 rpm. 3) When the motor starts or stops, the pressure rise ratio effects decisively to the max. torque.

가변하중을 받는 유압실린더의 제어특성개선

염만오,Yum, Man-Oh 한국기계가공학회 2003 한국기계가공학회지 Vol.2 No.4

For position control of electro-hydraulic servo system, single rod cylinders and double rod cylinders are used. Single rod cylinders have simple structure for manufacturing but different volume ratio of two sides induce to non-linearity in process of then mathematical modeling. So only with conventional PID control method it is difficult to control single rod cylinders precisely. For mole precise position control of single rod cylinders, a controller which is inserted a velocity feedback PID controller and MRAC controller are proposed. With experiment control performances of three control methods are compared. In case of experiment, for external varying load to the system, a hydraulic cylinder and a pressure control valve are used. In conclusion a MRAC is considered a suitable control method for external varying load.

동력 절약형 유압유니트 제안 및 제어기 설계

염만오,이상윤,Yum, Man-Oh,Lee, Sang-Yun 한국생산제조학회 2010 한국생산제조학회지 Vol.25 No.3

In a conventional system, hydraulic unit pumps out pressurized oil when the power use is not even necessary. As a result, it causes much power loss. This study is on the proposal of new hydraulic unit which controls the revolution of the pump in order to produce proper power needed and to have good response characteristic. In addition, the existing control methods such as PID control method, fuzzy control method, and adaptive control method are applied to the proposed hydraulic unit. Then the best control method is selected and the controller is developed to realize minimum power loss.

고속 CNC선반용 공랭식 오일 냉각기 개발

염만오,Yum, Man-Oh 한국기계가공학회 2003 한국기계가공학회지 Vol.2 No.4

Recently, CNC lathe is in need of higher speed for precision works. So more intensive and compact heat exchanger is necessary to cool down the heat in short time from drills and works during high speed working. In this study, to increase heat transfer coefficient per unit volume, inner groove tube is designed and compact oil cooler, 57% volume of conventional type, is manufactured. The heat transfer performance is experimented and is compared with the performance of conventional type.

동력 절약형 유압유니트 제안 및 제어기 설계

염만오(Man-Oh Yum),이상윤(Sang-Yun Lee) 한국생산제조학회 2010 한국생산제조학회지 Vol.19 No.1

In a conventional system, hydraulic unit pumps out pressurized oil when the power use is not even necessary. As a result, it causes much power loss. This study is on the proposal of new hydraulic unit which controls the revolution of the pump in order to produce proper power needed and to have good response characteristic. In addition, the existing control methods such as PID control method, fuzzy control method, and adaptive control method are applied to the proposed hydraulic unit. Then the best control method is selected and the controller is developed to realize minimum power loss.

개발한 국산화 유압 액셜피스톤모터의 특성실험

염만오(Man-oh Yum),이상윤(Sang-Yun Lee) 한국생산제조학회 2007 한국생산제조학회지 Vol.16 No.5

The purpose of this study is to analyze the characteristics of a domestic developed hydraulic axial piston motor. An experimental apparatus was constructed and the output torque, the input oil pressure, the input flow rate, the speed of motor and oil temperature were measured. They were measured under both no load and load conditions. The results are as follows; 1. Motion of motor became steady state conditions after 5 seconds. 2. Output torque of motor was proportional to input oil pressure under both load and unload. 3. Speed of motor decreased with increasing load. 4. Oil temperature was almost constant. The results of this study will offer the basic data in designing and operating hydraulic axial piston motors.

적응제어를 이용한 유압 액츄에이터의 특성개선에 관한 연구

염만오(Man Oh Yum),윤일로(Il Ro Yoon) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.1

A hydraulic system is difficult to keep the performance due to non-linearity, load pressure which changes according to working condition and system parameter variation, the requirement of control algorithm has been risen in order to satisfy them. An adaptive control is a control method which is suggested to achieve a control object though plant characteristics change. In spite of the case that plant characteristics and the degree of variation are difficult to grasp, adaptive control can keep the characteristics of closed-loop system regularly. In this study GMVAC(generalized minimum variance adaptive control) combined with output error feedback is proposed in order to solve problems of non-minimum phase, vibration and overshoot in initial response of the plant. The control performance according to the variation of characteristics of the plant is evaluated by changing the supply pressure only.

분산계 ER유체의 빙햄특성에 관한 기초적 연구

장성철,염만오,Jang, Sung-Cheol,Yum, Man-Oh 한국기계가공학회 2003 한국기계가공학회지 Vol.2 No.3

This study investigates the effect of temperature and electric field strength on the Bingham characteristics of Electro-Rheological(ER) fluids which change their Yield shear stress and viscosity by temperature and electric field strength. It is found that under constant temperature the Yield sheal stress and viscosity of ER fluids proportionally increase with the applied electric field strength, and under constant applied electric field strength the Yield shear stress and viscosity of ER fluids decrease with the increasing temperature. These results are considered to be applied to the fluid and pneumatic power industry.

유체커플링에서 유량과 동력전달특성에 관한 실험적 연구

박용호,문동철,염만오,Pak, Yong-Ho,Moon, Dong-Cheol,Yum, Man-Oh 한국정밀공학회 1995 한국정밀공학회지 Vol.12 No.11

The fluid coupling combined with a pump and a turbine have many merits compared with other couplings, their uses are increesing rapidly in various industrial fields at home and abroad in pursuit of high-speed more efficiency durability of various mechanic devices. The authorities concerned have recognized the improtance of the fluid coupling and supported its developement and now some trial products began to show up. As the structrue and characteristics of the fluid coupling have little similarity to other kinds of couplings and its fluid behavior is unique, so its characteristic analysis is expected to be difficult. Until now no satisfactory study on the characteristics of the fluid coupling seems to have been conducted at home, so a study on this field needs to be done urgently. The purpose of this research is to construct the experimental test set-ups and establish a series of performance test program for the domestically developed fluid couplings and to provide a software to store and utilize these experimental data which can be used to improve the performance of the fluid coupling and solve on the job problems confronted in operation. The performance test consists of taking measurment of torque, rpm and efficiency of the fluid coupling for three different amount of working fluid inside with various loads to the output shaft and finally infestigating the torque, rpm and efficiency characteristics of the fluid coupling with respect to these parameters. The results of this study can contribute valuable references to the development of variable speed fluid coupling and torque converter currently pursued by the domestic industry.