• Journal of Energy Engineering
• /
• v.8 no.4
• /
• pp.592-604
• /
• 1999

The steady state and dynamic characteristics of large cell area MCFC stacks were analyzed to solve the problems such as temperature difference generated in stacks and pressure difference between anode and cathode. Manipulated variables (current density, duel utilization rate, oxidant utilization rate) and controlled variables (temperature difference, anode and cathode pressure difference) which had an important effect on the MCFC stack performance were determined using operation results of two types of MCFC stacks (5kW (3,000 $\textrm{cm}^2$, 20 ea). 3kW (6,000 $\textrm{cm}^2$, 5ea)). The stability and transfer function representing system dynamics were obtained by steady state gain rate which showed the relative change between MVs and CVs. The transfer function was a 3$\times$3 matrix and a typical first order system without time delay. The optimal operating condition of large cell area MCFC stacks could be determined by analyzing dynamic characteristics. In case of a 5 kW MCFC stack, pressurized operation with recycle flow should be used to control the outlet temperature less than 68$0^{\circ}C$ and to control the MCFC system effectively. MIMO control or decoupler should be used to remove the interaction between MVs and CVs. This result will be used as important data in determining the control structure design and operation mode of large cell area MCFC systems in the future.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.6 no.4 s.23
• /
• pp.15-20
• /
• 2006

This study developed integration control system that improve efficiency and give flexibility of smoke control system and can improve prevention of disasters performance. The reliable each kind sensor and of integration control system was developed by establishing the specifications, algorithms and constructing engineering data. More correct and reliable control function of optimization can be obtained by the central control from integration control system rather than the existent individual control. This sees to do to impose flexibility to smoke control system. Also, this will provide the basics of integration control system and ability security of smoke control system and can construct smoke control system of performance based.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.2
• /
• pp.95-101
• /
• 2006

A fuel metering unit using PWM(Pulse Width Modulated) solenoid valve has some advantages such as low cost, small size and simple structure. The mathematical model and its experimental rig of the fuel metering unit using PWM solenoid valve and CPDV(Constant Pressure Drop Valve) for miniature turbo engines were constructed. As the results of simulation, some major parameters which have dominant effects on the performance were found. And the experimental results verified the validity of established model by showing the good agreement with the numerical simulation results. Hence, this system modeling could be used effectively in the actual development of a PWM fuel control system.

• Journal of Energy Engineering
• /
• v.15 no.1 s.45
• /
• pp.67-73
• /
• 2006

A calculation method on performance impact of the controllable operations parameter such as GT inlet filter ${\Delta}P$, compressor efficiency, and condenser pressure was devised to achieve best performance of combined cycle power plant with the on-line performance monitoring system. This method calculates the performance impact on the deviation between 'Expected' values and 'Actual' values. Controllable parameter targets are determined based on achievable performance given existing equipments and control conditions.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.06a
• /
• pp.852-855
• /
• 2009

고압 미분탄 공급 기술은 건식 석탄가스화기 시스템의 안정적인 연속운전을 위한 핵심이 되는 기술로서, 본 연구에서는 스크류피더 방식 및 기류수송 방식의 pilot급 고압 미분탄 공급장치를 이용한 미분탄 공급량 제어 기술 개발을 진행하였다. 그리고, 일반적으로 dense phase 형태로 다량의 미분탄을 공급하는 기류수송 방식 고압 미분탄 공급장치에서 가스화기로 공급되는 미분탄의 공급량을 감소시키기 위하여 다공 chamber를 통하여 가압 질소를 공급할 경우, 차압이 증가함에 따라 미분탄의 공급량이 증가하기는 하지만 lean 또는 medium phase 형태로 미분탄 공급량 제어가 가능함을 확인할 수 있었다.

• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.77-82
• /
• 2009

If we can supply accurate minute flow rate to the households, we can solve many problems that are occurring in consequences of uncontrolled flow rate for the households. Therefore, this paper presents an innovative solution to the source of the problems by illustrating how we can control the flow rate to the household. This paper proves such problems even can be solved in a case when there is a room turned off the heating.

• Journal of the Korea Convergence Society
• /
• v.13 no.3
• /
• pp.191-196
• /
• 2022

Unlike an international combustion engine car, a battery-powered electric vehicle requires an additional heat source for its heating system. A high-voltage coolant heater has the advantages of high efficiency and a wide operating temperature range. In its development, the geometry design of the coolant flow path is essential. This paper presents the thermal flow simulations of a 7kW high-voltage heater with symmetric serpentine flow channels arranged parallelly. The heater performance was evaluated from the simulation results in terms of the pressure and temperature differences and the flow uniformity. The proposed design showed a greater flow resistance and similar heat exchanging capability than the existing parallel serpentine design. It has the advantage of a relatively wide low-temperature surface area, where the control circuit board susceptible to high temperatures can be located.

• Journal of Industrial Technology
• /
• v.22 no.A
• /
• pp.89-94
• /
• 2002

In this paper, a Exhaust Flow Controller (EFC) technology for uniform application of film coater and developer device is introduced that spread and remove photo resister at semiconductor manufacturing process. Because developed EFC device uses differential pressure sensing method as a differential flow meter and embodied smart A/D conversion by using a one chip microprocessor and devised by feedback Servo control, It has shown excellent performance and stability evaluation, as maximum 2000L/min flow, capability of installation to actual semiconductor equipment.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.13 no.1
• /
• pp.63-68
• /
• 2004

Recently ER fluids are put to practical use in fluid power industry field. As only with electrical signal change to the valve in which ER fluid flowing, ER fluid flow is controlled, so devepment of simple ER valves have been tried. In this case a technical problem is to check the pressure drop caused from flow rate change in valves because the pressure drop is very small. In this study ER valves are designed and manufactured, and small pressure drop induced from flow rate change is checked by pressure transducer which is made with appling strain gage. The ER valves and pressure drop check method are considered to be applied to the fluid power industry.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.8 no.4 s.23
• /
• pp.152-158
• /
• 2005

In this paper, we have proposed a fuel metering unit of ai breathing engine. The proposed valve system consists of a constant pressure drop valve and a metering valve, which are controlled by servovalve. We carried out nonlinear and linear analysis, computer simulation and experimentation to find effects of some factors on system performance. Analysis and experimental results show a good agreement. It is also shown that the system stability is affected by pressure drop of metering valve and inlet pressure of injectors.