• Journal of Drive and Control
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• v.12 no.4
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• pp.21-27
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• 2015

The accurate position control of pneumatic driving apparatus is considered in this paper. In pneumatically actuated positioning systems, accurate positioning as an electrical servo has been known to be difficult because of the friction force and compressibility of the air. For good control performance of the pneumatic system, an actuator mounted with externally pressurized air bearings is produced to compensate for friction force. For the controller design, the governing equation of the pneumatic driving apparatus is derived. In order to reduce the nonlinear characteristics of the control valve, linearized control input is derived from the relation between the effective area of the valve and the control input. The experimental results are presented to show the results of the improved position control of the pneumatic driving apparatus.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1614-1619
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• 2003

In this study, position and force simultaneous trajectory tracking control system with pneumatic cylinder driving apparatus is proposed. The pneumatic cylinder driving apparatus that consists of two pneumatic cylinders constrained in series and two proportional flow control valves offers a considerable advantage as to non-interaction of the actuators because of the low stiffness of the pneumatic cylinders. The controller applied to the driving system is composed of a non-interaction controller to compensate for interaction of two cylinders and a disturbance observer to reduce the effect of model discrepancy of the driving system in the low frequency range that cannot be suppressed by the non-interaction controller. The experimental results with the proposed control system show that the interacting effects of two cylinders are eliminated remarkably and the proposed control system tracks the given position and force trajectories accurately.

• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.13-16
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• 2012

본 논문에서는 항공기의 제어 안정성(Control Stability)과 조종성(Controllability), 그리고 기계 하중을 줄여 구조와 공기역학적인 안정성을 향상시키기 위해 고양력장치(High-lift Device)인 플랩에 탭이 추가된 익형을 설계하였다. 이 과정에서 한정된 해석자원 때문에 많은 설계조건을 해석하는데 어려움이 있었다. 이를 해결 하기위해 얇은 익형 해석(Thin Airfoil Theory)을 이용하여 지정된 설계구속조건을 통해 시위선을 지정하고 이를 바탕으로 두께를 부여하여 최종적인 익형을 설계하였다. EDISON CFD 2.0 Solver를 이용해 최종 설계한 익형의 성능을 해석하였다. 이를 바탕으로 플랩만 존재하는 익형에 비해 양력손실률이 15%이하로 감소하고, 힌지 모멘트가 최소인 공기역학적 익형을 산출하였다.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.3
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• pp.8-13
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• 2011

In the present study, a robust controller has been designed to control force for a pneumatic driving system considering the effect of a transmission line. Transfer characteristics of pneumatic transmission line should be changed according to the velocity of the air going through the transmission line. The designed controller is composed of two parts. The one is a feedback controller, which is composed of a stabilizing filter, a compensating filter of modelling error and a nominal model of the force control system, to compensate the influence of transmission line and improve the feedback characteristics of the control system, and, the other is a feedforward controller to achieve the control performance. Control results with the designed controller show that the robustness and performance of the control system are improved compared to the control results with a fixed gain controller.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.1
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• pp.1-5
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• 2008

Pneumatic driving systems have hard non-linear characteristic and large friction force compared with driving power. Hence, it cannot be robust against parameter uncertainties, modelling error, disturbance and noise. In this study, we apply a mixed $H_2/H_{\infty}$ control to the generalized plant for a pneumatic driving apparatus system including parameter uncertainty and disturbance. In order to design the $H_2/H_{\infty}$ controller, we use the LMI technique. To evaluate control performance and robust stability of the designed controller, we compare it with a conventional controller such as PVA(Position-Velocity-Acceleration state controller) using the simulation results. As a result, it can be known that designed controller shows better robust stability than the conventional controller.

• Journal of Welding and Joining
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• v.14 no.3
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• pp.29-40
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• 1996

Electron beam 용접은 전자총에서 발생된 electron beam을 렌즈로 집속시켜 고 에너지의 열원을 얻는 것을 기본 원리로 하고 있다. Electron beam은 렌즈에 의해 매우 작게 집속(0.1 - 1mm.PHI.)시켜 높은 에너지밀도로 만들 수 있으므로 용접을 매우 깊게(수십 - 수백 mm) 할 수 있다. 이러한 용접 특성은 모재의 열변형을 최소로 하여 용접 부위가 원래의 성질을 잃어버리는 것을 최소화한다. 그러나, deep welding 의 경우 입력 파워 밀도가 너무 큰 관계로 계면 부위가 기계적 충격에 약하다는 단점 을 갖고 있다. Electron beam 용접은 서로 다른 금속을 filler material 없이 용접할 수 있으며 복잡한 구조의 용접이 가능하다. 또한 대부분의 electron beam 용접은 진공 중에서 이루어지기 때문에 공기의 영향을 받지 않는다는(산화 방식) 특성을 갖고 있다. 즉, 공기와의 접촉이 적기 때문에 산화가 방지되고 용접 순도가 매우 높다는 장점을 갖고 있다. 이는 반면 장치가 거대해지고 비싸다는 단점으로 작용한다. 1980년대 부터 이러한 단점의 극복을 위해서 대기중에서의 electron beam 용접에 관한 연구가 수행 되어 실용화 단계에 이루고 있다. 최근 전자, computer기술의 발달로 electron beam 출력을 더욱 더 정밀하게 조절할 수 있고, computer와 sensor의 결합으로 자동용접 위치 제어와 NC(Numerical Control) 작업대의 설치로 완전 자동화 용접 공정이 가능 하다. 그 결과 높은 용접 속도를 얻을 수 있으며 무인 생산 체계에로의 응용이 가능 하다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.592-594
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• 2017

본 연구는 기존의 실내 환경 관리시스템의 단순함에 퍼지이론을 부가하여 지능적으로 관리하는 것을 제안한다. 이 장치는 실내의 온도, 습도, 공기 오염도를 센서를 사용하여 측정한 후, 이를 아두이노를 활용한 제어 프로그램으로 보낸다. 계절별 적정 환경을 기준으로 만든 퍼지 규칙을 통해 쾌적한 실내 환경을 만들 수 있도록 에어컨, 제습기, 공기청정기를 제어하여 자동으로 실내의 환경을 관리해주는 지능적인 IoT 환경을 구축한다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.127-129
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• 2011

In the building, controlling temperature is main concern for maintaining fresh environment. To control temperature, phase change material(PCM) can be used as a medium that keeps temperature in certain level. PCM has its own phase change temperature. PCM melts/solidifies while absorbing/releasing the heat. Because of the advantage, PCM can be applied to a air-PCM heat exchanger. In this study, the air-PCM heat exchanger was designed based on the system requirements and experimental analysis was conducted to study on the performance of the heat exchanger.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.131-139
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• 2001

Highly accurate control of the air-fuel ratio is important to reduce exhaust gas emissions of the gaseous-fuel engines. In order to achieve this purpose, inlet air mass flow must be measured exactly, and precise engine models are necessary to design engine control systems. In this paper, the effects of water vapor and gaseous fuel that change the air mass flow are studied. The effective air mass ratio is defined as the air mass flow divided by the mixture mass flow, and also it is applied to the estimation of the inlet air mass flow. The presence of the gaseous fuel and the water vapor in the mixture reduces the air partial pressure and the effective air mass ratio of the gaseous-fuel engines. The Experimental results for an LPG engine show that the estimation of the inlet ai mass flow based upon the effective air mass ratio is more accurate than that of the normal air mass flow.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.26-31
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• 2011

In this study, it made to run conventional single direct injection(DI) diesel engine, which adapted bulk combustion system not following spark ignition system without any ignition apparatus. It was heated and controlled inlet-air into conventional single DI diesel engine. The maximum value of brake thermal efficiency was at 35 region of air-fuel ratio. On the contrary, when the region of air-fuel ratio leaner than 35, brake thermal efficiency was decreased suddenly. And brake thermal efficiency was increased as much as inlet-air heating temperature increased. So, when air-fuel ratio was decreased and inlet-air heating temperature was higher, the engine was in optimal operation condition.