• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.424-427
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• 2002

Pneumatic control systems have the potential to provide high output power to weight and size ratios at a relatively low cost. However, they are mainly employed in open-loop control applications where positioning repeatability is not of great importance. This paper presents precision positioning control of pneumatic servo cylinder with on-off valve, Pneumatic low-friction cylinder with servo valve and DC servo motor under parameter variations. Basically positioning control uses PID controller, where needs a linearized model. A neural network is added to a PID controller to compensator nonlinearity of the system and an influence of friction force is consider as disturbance. The performances of the proposed algorithms were compared by experiments with them of PID controller. From those experiments is was shown that the proposed algorithms are more efficient about settling time, steady 7tate error and overshoot than PID control algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.636-639
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• 1996

We have developed a part of hydraulic stroke sensing cylinder using magnetic sensor that can detect each position under severe construction fields. In this paper, for evaluating the developed cylinder under various environment condition, thermal control systems and two hydraulic systems to be coupled consist of. The former is composed of an heater case, temperature sensor, and interface circuits which include SCR(silicon controlled rectifier) for the control of the voltage's phase. The latter is composed of an hydraulic cylinder for position control with solenoid valve (ON/OFF motion) and a load cylinder with proportional reducing valve. To obtain the various performance evaluation, it is carried out under high temperature condition in thermal system controlled by using Ziegler-Nichols PID tuning method and artificial disturbances such as impulse or constant force. The results show that the developed cylinder has good performance under the various environment condition.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.555-560
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• 2000

The modeling and the numerical analysis are done so as to develop the Computer Aided Design program for the design of flow control valve attached to the vane pump. The factors affecting the flow rate characteristics, are analyzed by the experiments and the numerical methods. It is shown that the main factor affecting to the first control flow is the diameter of small rod of the spool, the main factor affecting to the second control flow is the diameter of big rod of the spool, the main factors affecting to the cut off are the main spring constant, the initial displacement of main spring and small diameter of the spool, and the dropping slope characteristics of flow rate are decided by the chamfer of spool and the dynamic characteristics of the spool.

• Journal of Biosystems Engineering
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• 제17권1호
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• pp.18-26
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• 1992

A mechanical-hydraulic hitch control system has been adapted to most agricultural tractors. But it has various defects due to friction, inertia and hysteresis. Recently a number of electronic-hydraulic hitch control systems have been developed in several countries to improve control performance of the agricultural tractors equipped with a mechanical-hydraulic hitch control system. This study was conducted to develop a new electronic-hydraulic hitch control system using an electro-hydraulic servo valve instead of an on-off valve and to carry out computer simulation of the system. According to the result of computer simulation, the control system showed the best performance when the proportional constants were 9 and 4 for position and draft control respectively. The step and frequency responses were improved as flow rate increased.

• 대한기계학회논문집
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• 제11권3호
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• pp.465-472
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• 1987

본 연구에서는 솔레노이드 밸브를 사용한 유압위치제어 시스템에 위에서 언급 한 두가지 단속적 제어 방법을 적용하여 각각의 제어변수들과 부하조건이 시스템의 시 간 영역에서의 응답특성에 미치는 영향을 실험적으로 규명하고 각각의 제어특성을 비 교 고찰하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제30권1호
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• pp.42-49
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• 2006

In this research. the diesel cycle was thermodynamically interpreted to evaluate the possibility of high efficiency by converting diesel engines to the high expansion diesel cycle, and general cycle features were analyzed after comparing these two cycles. Based on these analyses. an experimental single cylinder a long stroke with high expansion-diesel engine. of which S/B ratio was more than 3, was manufactured. After evaluating the base engine through basic experiments, a diesel engine was converted into the high expansion diesel engine by establish VCR device and VVT system Accordingly, the high expansion diesel cycle can be implemented when the quantity of intake air is compensated by supercharge and the effective compression ratio is maintained at its initial level through the reduction of the clearance volume. In this case, heat efficiency increased by $5.0\%$ at the same expansion-compression ratio when the apparent compression ratio was 20 and the fuel cut off ratio was 2. As explained above, when the atkinson cycle was used for diesel cycle, heat efficiency was improved. In order to realize high expansion through retarding the intake value closing time, the engine needs to be equipped with variable valve timing equipment, variable compression ratio equipment and supercharged pressure equipment. Then a high expansion diesel cycle engine is realized.

• 한국가스학회지
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• 제23권2호
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• pp.28-34
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• 2019

현재 울산국가산업단지에는 생산량의 증대와 이송의 편의를 위해 막대한 규모의 지하매설배관이 설치되어 있다. 현재 울산국가산업단지에는 62개 사에 총 1,293km의 지하배관이 설치되어 있으며, 이 중에서 상당수는 사업장 외부에 설치되어 있다. 최근 3년간 울산국가산업단지에서는 5건의 누출사고가 발생하였으며, 대응시간은 평균 8시간 이상 걸렸다. 이러한 사고대응의 지체는 심각한 2차 사고로 이어질 수 있으며, 이는 지역주민들에게 큰 위험을 줄 수도 있다. 본 연구에서는 지하매설배관에 긴급차단장치를 설치하는 경우 사고영향평가를 통해 얼마나 누출사고의 영향이 경감되는지 분석하였다. 본 연구의 결과를 통해 긴급차단장치 설치가 지하매설배관의 누출사고의 피해를 줄이는 데 큰 역할을 할 수 있음을 검증하였다. 향후, 지하매설배관의 안전성 향상을 위해 시급히 긴급차단장치의 설치를 입법화하고 실행되어야 할 것이다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 춘계학술대회 논문집
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• pp.380-384
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• 1992

The position control of a pneumatic cylinder suing low cost on-off valves is studied. The valve control band(VCB) was proposed toget fast response and toprevent solenoid valves from unnecessary switching at the beginning of response. A learning algorithm was used to compensate the nonlinearity and complexity in mathematical modelling of pheumatic on-off controlled positioning systems. In this algorithm, the desired performance index and modified learning rate, were proposed to improvespeed and convergence of learning control. It is shown experimentally that the proposed algorithm is robust to changes of system parameters: the setting time less than 1.0 sec and the error bound of .+-. 0.1 mm can be obtained. The effects of supply pressure, size of switching valves and the effect of multiple valves are discussed, and computer simulation onthe dynamic performances of the pneumatic system is also presented.

• 한국자동차공학회논문집
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• 제5권1호
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• pp.1-13
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• 1997

The key point that guarantees the durability of the ceramic monolith filter is to lower peak temperature and temperature gradient inside filter during regeneration. The control of the exhaust gas flow rate into the filter, by the bypass technique of the exhaust gas, enables the gas temperature in filter to be constant for regeneration. A couple of methods, which are the ON/OFF and PID control of the bypass valve, were used for feedback control of the gas temperature. These techniques showed that the ceramic filter was regenerated perfectly under the peak temperature and peak temperature gradient limitations for durability.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.154-155
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• 2007

Put Recently, development of micro valves that operate by compressed air has received significant attention in the fields of the micro fluid chip for medical applications or production lines of semi-conduct chip for electronic goods. Especially it is required that high-speed responsibility and lower power in optimal design of these micro valves. The primary objective of this study is to compare the optimally designed Solenoid Valve with the actually produced one which can highly improve the efficiency by providing optimal current according to mechanical load.