• Journal of Biosystems Engineering
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• 제21권2호
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• pp.155-166
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• 1996

A direct injection sprayer was designed using the concepts of injection mixing and total flow control, flowrate-based system compensating for the variation of forwarding speed. A metered rate, proportionally to the actual diluent flow rate, of a tracer chemical was injected directly into the diluent stream. The injection of chemical may improve the precision and safety of chemical application process. The control system was evaluated for the variables of the control interval, tolerances and sensitivities of flow regulation valve and injection pump. Performance of the system was assessed as that the response time of flow rate, response time of injection rate, absolute steady state error, and the coefficient of variance(C.V.) of concentration were 8.5 and -0.53 seconds, 0.067 lpm(0.8%) and 3.15%, respectively, at optimal parameters of control interval of 1.0 sec, fast sensitivity of flow regulation valve, medium sensitivity of injection pump and medium tolerance of flow rate. Performance of the system can be improved by increasing the sensitivity of flow regulating valve and employing a high resolution velocimeter, such as Doppler radar.

• 설비공학논문집
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• 제13권9호
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• pp.810-817
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• 2001

Performance of a water-to-water multi-type heat pump system using R22 which has tow indoor units has been investigated experimentally. The refrigerant flow rate of each indoor unit was regulated by an electronic expansion valve and the total refrigerant flow rate of the system was controlled by a variable speed compressor. In the system, evaporator outlet pressure of refrigerant and outlet temperatures of secondary fluid from indoor units were selected as control variables. Experiments were executed for both cooling and heating modes using PID control method with fuzzy logic, and results of the test are compared with a classical PID method. In the case of PID control with fuzzy logic, the fuzzy control rules corrects PID parameters each time. Results show that PID control with fuzzy logic has the merits of quick response and reduced overshoot.

• 유공압시스템학회논문집
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• 제6권2호
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• pp.14-21
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• 2009

The typical hydraulic hoisting system of the rack-bar type sluice gate is composed of a hydraulic supply unit using an uni-directional pump, a direction control valve, a hydraulic motor, a counter balance valve, and flow control valves. Here, the hydrostatic transmission is applied to the hoisting system of rack-bar type sluice gate to simplify the operation of gate such that the upward and downward direction of gate is simply controlled by the direction of pump rotation. The new hydraulic hoisting system is composed of a bi-directional pump, a hydraulic motor, two counter balance valves, two check valves, two pilot-operated check valves, two relief valves and a shuttle valve. The characteristics of a suggested system are analyzed by computer simulations.

• 한국생산제조학회지
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• 제26권4호
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• pp.387-394
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• 2017

This paper develops a pump system for patient with chronic pain or cancer. The pump module is consists of two micro-valve and membrane. The micro-valve is operated by a solenoid. With two solenoid valves which are connected via a drug transport line, the inlet and outlet are completely blocked. A silicon rubber membrane located between the two valves makes the flow-rate constant without any backflow. This pump module can control the flow-rate of drugs by controlling the time that the valves are opened and closed. The reservoir consists of a drug chamber and a gas chamber. As the gas chamber encloses the drug chamber, propellant gas which is injected into the gas chamber pressurizes the drug chamber regardless of volume of the drug chamber. To design the pump module, analysis a constant efficiency test, and accuracy test for the pump module were conducted.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.643-646
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• 2000

As many industrial systems become more complex, it becomes extremely difficult to diagnose the cause of failures. This paper presents a failure diagnosis approach based on discrete event system theory. In particular, the approach is a hybrid of event-based and state-based ones leading to a simpler failure diagnoser with supervisory control capability. The design procedure is presented along with a pump-valve system as an example.

• 동력기계공학회지
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• 제17권6호
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• pp.5-10
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• 2013

Diesel engines have the advantages of good fuel efficiency and low emissions. Therefore, car makers have been developed various kinds of diesel engine management system to clean up emissions while improving fuel efficiency. One of them is the common rail system. In the common rail system, diesel fuel is injected into the combustion chamber at ultra high pressures up to 1,800 bar to ensure more complete combustion for cleaner exhaust gas, and highly precise multiple injection reduces NOx emission, combustion noise and vibration. Generally speaking, common rail system consists of booster pump, high pressure pump, common rail, injectors, control valves, and sensors. The high pressure pump receives low pressure fuel from the booster pump and supply high pressure fuel to injectors through the high pressure common injection rail. Therefore, high pressure pump has an important role in common rail system. In this paper, we have investigated the performance of high pressure pump of common rail system.

• 설비공학논문집
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• 제20권6호
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• pp.365-371
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• 2008

Condensing gas boiler units may make a big role for the reduction of energy consumption in heating industries. In order to decrease the energy consumption of a condensing gas boiler unit, effective operations of the system are necessary. In this study, mathematical models of a condensing gas boiler system were developed in order to develop control algorithms of the system. These include dynamic models of a blower, a gas valve, a pump, a burner, a boiler heat exchanger, and a hot water heat exchanger. Control algorithms of a blower, a gas valve, and a pump were also assumed. Simulation results showed good predictions of dynamic behaviors of a boiler system. Therefore, the simulation program developed for this study may be effectively used for the development of control algorithms of a boiler system.

• 한국추진공학회지
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• 제9권3호
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• pp.74-84
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• 2005

본 논문에서는 AMESim(상용 소프트웨어)을 이용, 개방형 터보펌프식 엔진시스템을 모델로 하여 산업용 제어밸브를 적용한 시스템의 특성을 미리 확인하였다. 그 결과물을 토대로 하여 앞으로 발사체 제어밸브 개발할 계획이며, 밸브와 연계된 제어 및 밸브시험을 위한 설비 특성을 예측해 보았다. 시스템시험을 위해 장착할 각 산업용 제어밸브의 PID 값을 찾고자 하였으며, PI 및 PID 제어 방식을 이용하여 제어밸브의 과도 및 정상상태의 유동특성을 비교분석하였다. 제어밸브를 이용하여 추력제어 및 TDS 구현을 목적으로 하는 밸브설계와 시스템의 종합 모사시험을 위한 설비의 설계 조건을 또한 제시하였다.

• 한국정보통신학회논문지
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• 제7권5호
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• pp.1026-1031
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• 2003

자동 급수펌프는 압력스위치에 의해 운전 및 정지를 하게 된다. 따라서 수량 증감에 따른 펌프의 빈번한 운전 및 정지로 인해 지속적인 정격 및 정압 운전이 불가능하다. 또한 빈번한 작동으로 인해 지속적으로 일정한 압력을 얻을 수 없으며, 펌프의 소손과 에너지의 낭비가 심한 단점을 가지고 있다. 본 논문에서는 이러한 단점을 해결하고자 급수밸브, 유량센서, 제어장치로 구성되는 정압 급수장치를 설계 제작하였다. 급수밸브는 유출되는 물의 양과 관계없이 항상 일정한 양의 물을 유입하여 펌프의 부하를 줄이는 역할을 한다. 유량센서는 적외선 다이오드를 사용하여 유출되는 물의 양의 측정하며, 제어장치는 8 비트 마이크로프로세서를 이용하여 설계하였으며, 특별한 제어 알고리듬에 의해 펌프의 운전과 정지를 제어하게 하였다. 본 논문에서 개발한 장치는 토출 압력이 일정하게 유지되고 펌프의 작동 및 정지 동작이 부드럽게 이루어지며, 펌프의 지속적인 정압운전이 가능하므로 기존의 단점을 보완하는 장치로 사료된다.

• Journal of Biosystems Engineering
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• 제27권2호
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• pp.79-88
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• 2002

This study was conducted to develop system for high speed rice transplanting machines. The control system includes a sensor detecting the tilt angle of the seedling bed, a micro-controller and a hydraulic system consisting of a double acting cylinder, a four-way three-position solenoid valve, a relief valve and a hydraulic pump. The levelling system shared the pump with the existing steering control, resulting in a tandem center circuit for the steering and levelling control systems. Using the input signal from the sensor, the micro-controller determined and generated the output signal to control the cylinder through the solenoid valve to keep the seedling bed always parallel to the water surface regardless of soil unevenness during the transplanting operations. Both an ON/OFF and a PWM control schemes were tested. When the flow rate was more than 1 ι/min in the ON/OFF control, the system showed unstable rolling. However, in the PWM control, the system worked stably although the flow rate was more than 1 ι/min. The PWM control showed a better performance when a large difference between the angle and the dead band of the control system occurred. The characteristics of tile system response to given tilt angles were predicted by a computer simulation. Both the ON/OFF and the PWM control systems worked well providing that the operating and waiting times were properly adjusted.