• The KSFM Journal of Fluid Machinery
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• v.18 no.2
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• pp.67-72
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• 2015

The purpose of this study is to achieve energy saving effect of inverter driving multistage centrifugal pump. For determining the operation points in the pump system, the system curves should be obtained experimentally. To get the system curves, three pumps combined in parallel and one pump operated with different rotational speeds. But for variable speed pump system, energy saving rates can not be evaluated from operation efficiencies. That is why operation efficiencies, system curves, duty cycles, and input powers of the pump system were measured by the constructed experimental apparatus. The duty cycle segmented into different flow rates and weighting the average value for each segment by the interval time. The system was operated with two different periods. The mean duty cycles were collected from apartment and found that the system operated at 40% and at 50% or below capacity. Measured energy saving rate was 58.16%. Estimating method of energy saving rate could be more effective operation index than that of operation efficiency.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.6
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• pp.37-47
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• 2001

Due to the friction characteristics of pump, cylinder packing and passenger car, in the elevator actuated with hydraulic inverter-fed systems, there exist dead zones, which cannot be controlled by a PID controller. To overcome the drawbacks, in this paper, we propose a new hybrid control scheme, which switches the modes between a sliding mode controller and a PID controller. The proposed hybrid control scheme achieves an improved control performance by using both controllers. We first propose a design method of sliding mode controller for a hydraulic elevator system controlled by inverters, then fellowed by a design method of a hybrid sliding mode control scheme is proposed. The effectiveness of the proposed control scheme are shown by simulation results, which the proposed hybrid control method yields better control performance then the PID controlled scheme, not only in the zero-crossing speed region but also in the overall control region including steady-state region.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.51-55
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• 2021

The nurses manually carry out the intravenous therapy for the patients. Using an Arduino, the fine flow controlling device was invented to provide an ongoing patient care. The medication is injected through a peristaltic pump, and the amount of the solution is controlled with a RGB color sensor. The power of the device is supplied through the batteries. An amount of the injection is measured with LIG strain sensor fabricated by 355nm UV pulsed laser. This system will provide a better medical service.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.4
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• pp.26-31
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• 2008

This paper deals with the issue of position tracking control of a clamp-cylinder for injection moulding machine with electric-hydrostatic drives. A fixed displacement pump is utilized in combination with AC motor in order to directly control a clamp-cylinder. A clamp-cylinder may be required to operate under a variety of operating conditions. Therefore, robust control performance is important in position tracking control applications. In order to accommodate mismatches between the real plant and the model used for controller design, discrete-time sliding mode control is developed by combining a velocity feedforward loop. From tracking control experiments, it is shown that significant reduction in position tracking error is achieved through the use of sliding mode control.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.233-238
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• 2024

The pipe cleaning process is a crucial step in the shipbuilding process of a shipyard. It involves removing foreign substances from the inside of the pipes before moving on to the stage of testing equipment after installing the pipes. If there are foreign substances inside the pipes and the equipment is tested, the foreign substances can enter the high-priced equipment and become a factor in the breakdown of pumps, gears, bearings, and other components. Especially in the case of pumps or hydraulic valves, even small foreign substances can lead to major accidents if they enter the equipment, and such equipment accidents can be a potential cause of major disasters, leading to accidents involving workers operating the equipment in the vicinity. Therefore, it is a process that shipyard customers, who are shipowners, also focus on and manage very intensively. To solve these problems, this study developed a system that can increase the cleaning effect of the cleaning fluid inside the pipes by increasing the flow of the cleaning fluid inside the pipes in the existing pipe cleaning method.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.1
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• pp.1-13
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• 2001

Due to the friction characteristics of cylinders and the rail of a passenger car, in the elevator actuated with hydraulic systems, there exist dead zones, which can not be controlled by a PID controller. To overcome the drawbacks, in this paper, we first try a hybrid controller which switches between a fuzzy logic controller and a PID controller. However, because the hybrid control scheme uses only a single type controller, except the switched layer, the high control performance can not be achieved. To solve this problem, we propose a new type fuzzy hybrid control scheme, which outputs of the output mixer arc controlled by a fuzzy logic. The hydraulic elevator system controlled by inverters has more then one switched layers due to the highly nonlinear characteristics. The proposed fuzzy hybrid control scheme achieves improved control performances by using both controllers with weighted outputs depend on the system status, to achieve improved control performances. The effectiveness of the proposed control scheme arc shown by simulation results, which the proposed fuzzy hybrid control method yields good control performance not only in the zero crossing speed region but also in the overall control region including steady-state region.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.19-19
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• 2017

자율주행 트랙터를 위한 트랙터 조향제어는 일반적으로 전자모터를 이용한 EPS(Electric Power Steering) 시스템을 스티어링 휠에 연결하여 회전변위를 변경하고 그 결과 오비트롤(Orbitrol) 밸브의 토출유량을 바꾸고 호스로 연결된 조향실린더의 변위를 조절하여 최종적으로 전방 타이어의 방향각을 변경하면서 이루어진다. 이러한 조향방식은 시스템 구조상 조향실린더와 오비트롤 밸브가 상대적으로 멀리 떨어져 있으며, 밸브 특성상 약 ${\pm}5^{\circ}$의 오버랩이 포함되어 있다. 또한, EPS의 전자모터는 관성력, 마찰, 백래시 등의 영향을 가진다. 이와 같은 복합적인 영향은 조향 응답을 느리게 만들어 상대적으로 빠른 속도에서 주행에서 추종성능이 떨어지는 문제가 발생한다. 본 연구에서는 자율주행 트랙터의 조향성능 개선 연구의 일환으로 조향 HILS 시뮬레이터를 설계제작하여 조향 성능의 요인을 실험적으로 구명하고자 하였으며 이를 바탕으로 조향 시스템의 설계개선 방안을 수립하고자 하였다. 시뮬레이터는 동양물산 80 마력급 TX803 트랙터에 사용되는 오픈센터방식의 오비트롤 유압회로 시스템을 기어펌프가 장착된 AC모터로 구동되게 구성하였으며, 유량은 모터의 주파수를 조절 회전속도를 조절 변경하였다. 추가적으로 EPS와 오비트롤 조합의 조향성능을 비교 및 개선하기 위해 비례제어밸브(PVG 32, Danfoss)를 추가 장착하였다. 실제 트랙터 조향 시 나타나는 마찰저항을 모사하기 위해 부하 실린더를 구성하였으며, 조향 실린더의 부하의 크기는 부하 실린더를 폐회로를 구성하고 유량비례제어밸브를 이용한 유로의 개구량 조절을 통해 부하의 크기를 약 4000 N 까지 증가시킬 수 있도록 하였다. EPS와 비례제어밸브를 제어하기 위해 CANoe 8.0 소프트웨어를 이용하여 CAN통신 기반 가상 조향ECU를 구성하였으며 오비트롤의 기본 성능을 확인하기 위해 조향휠에 따른 실린더 동특성 및 계단 추종성능을 비례제어밸브와 비교하였다. 오비트롤 밸브는 약 ${\pm}5^{\circ}$이상 동작 시 실린더 압력이 상승하기 시작하였으며, 이후 약 ${\pm}10^{\circ}$이상 동작 시 조향실린더가 동작하기 시작하였다. 계단 추종성능실험에서는 비례제어밸브가 약 2배 이상의 응답개선을 나타냈다. 자율주행 경로추종 성능을 향상시키기 위해서는 순간적인 출력밀도가 높은 비례제어밸브를 통해 응답개선이 필요한 것으로 나타났다.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.1
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• pp.1-7
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• 1998

Due to the increase in capacity of auxiliary machinery in power plant, the importance of energy saving has been greatly emphasized. If the speed of fans or pumps is controlled in accordance with the variation of load, large electric energy can be saved. Large capacity inverter, 2MVA GTO inverter, has been developed by operating two of 1MVA unit inverters in parallel. The parallel operation of the unit inverter is accomplished through two output transformers of which the secondary windings are connected in series. The system is composed of one control cubicle, one rectifier cubicle and 2 unit inverter cubicles. This inverter system was applied to the sea water lift pump(SLP) driven by a 6.6KV 1500KW induction motor in Seo-Inchon power plant to save the electric energy. The parallel operation of inverters by 180 degrees apart in switching frequency helps to reduce the harmonic components.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.3
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• pp.328-334
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• 1999

A fish pump makes very important roles in an automation system of an aquaculture farm, thus it has been used widely in order to transfer fishes from one place to the other place automatically. In spite of its significant roles, the efforts for developing performance and promoting efficiency of the fish pump are not sufficient yet. In this paper, a method which makes the fish pump automation system is suggested. Automation of the fish pump can be accomplished by using variable voltage and variable frequency inverter system including induction motors. Especially, very simple logic to generate Pulse width Modulation(PWM) wave to control induction motor efficiently and three steps speed control method to regulate liquid quantity of the fish pump simply are suggested. Owing to the simplifies speed control and PWM wave generation technique, a cheaper microprocessor, 80C196KC, than a digital signal Processor(DSP) can be used to operate control algorithm in induction motor systems for real time control Also, a new idea of remote control for the simplifies novel inverter system by Programmable logic Controller(PLC) without special output unit, digital to analog converter(D/A), is suggested in this paper. Consequently the function of reliability, availability and serviceability of the fish pump system are developed. It will be expected to contribute expanding of application of the fish pump in aquaculture farms because the system can reduce energy consumption and some difficulties according to manual operation prominently.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.491-494
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• 2008

최근 유비쿼터스의 활용이 확장되고 있다. 헬스분야에도 예외는 아니다. 기존의 헬스 싸이클은 단지 고정된 싸이클에 현재 자신의 속도와 맥박 등의 일반적인 정보만 제공하기 때문에 장시간이나 장기간의 운동을 하기에는 시간이 지날수록 흥미도가 떨어지고, 자신에 맞는 운동을 하기도 어렵다. 본 논문에서 논의하는 헬스 싸이클은 센서 네트워크와 DB를 접목한 상증 인식 시스템을 이용하여 자신이 현재 상태와 운동 진행 상태를 분석한 맞춤 운동을 할 수 있다. 사용자는 부착된 체온센서와 심전도센서를 통해서 자신의 상태를 실시간으로 확인하게 된다. 센싱된 신호들을 효율적으로 관리하기 위해서 센서네트워크를 형성하여 모든 신호들은 싱크노드에 집중되게 된다. 이 신호들과 DB에 기록된 사용자의 과거 운동기록을 활용하여 현재 운동중인 사용자의 신체적인 상태를 체하게 된다. 이러한 상황인식을 통해서 운동자에게 위험한 요소를 제거하거나 효과적인 운동이 가능하도록 자동으로 제어해주는 것이 이 헬스싸이클의 특징이다. 또한 여기에 충격감지 센서, 유압펌프제어, Python을 이용한 3D 게임엔진을 더하여 운동시에 가상현실적인 상황을 만들고자 하였으며 장시간의 운동에도 흥미가 떨어지지 않도록 하는 것도 상기 헬스싸이클의 특징이다.