• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.11
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• pp.1069-1076
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• 2007

This paper presents the road simulator control technology for reproducing the road input signal to implement the real road data. The simulator consists of the hydraulic pump, servo valve, hydraulic actuator and its control equipment. The QFT(Quantitative Feedback Theory) is utilized to control the simulator effectively. The control system illustrates a tracking performance of the closed-loop controller with low order transfer function G(s) and pre-filter F(s) for a parametric uncertain model. A force controller is designed to communicate the control signal between simulator and digital controller. Tracking specification is satisfied with upper and lower bound tolerances on the steep response of the system to the reference signal. The efficacy of the QFT force controller is verified through the numerical simulation, in which combined dynamics and actuation of the hydraulic servo system are tested. The simulation results show that the proposed control technique works well under uncertain hydraulic plant system. The conventional software (Labview) is used to make up for the real controller in the real-time basis, and the experimental works show that the proposed algorithm works well for a single road simulator.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.4
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• pp.285-291
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• 2004

A simulated moving bed (SMB) chromatography system is a powerful tool for preparative scale separation, which can be applied to the separation of chiral compound. We have de-signed our own lab-scale SMB chromatography using 5 HPLC pumps, 6 stainless steel columns and 4 multi-position valves, to separate a racemic mixture of ketoprofen in to its enantiomers. Our design has the characteristics of the low cost for assembly for the SMB chromatography and easy repair of the unit, which differs from the designs suggested by other investigators. It is possible for the flow path through each column to be independently changed by computer control, using 4 multi-position rotary valves and 5 HPLC solvent delivery pumps. In order to prove the operability of our SMB system, attempts were made to separate the (S)-ketoprofen enantiomer from a ketoprofen racemic mixture. The operating parameters of the SMB chromatography were calculated for ketoprofen separation from a batch chromatography experiment as well as by the triangle theory. With a feed concentration of 1 mg/mL, (S)-ketoprofen was obtained with a purity of 96% under the calculated operating conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.2
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• pp.240-253
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• 1996

The refrigeration cycle of automobile air-conditioners is simulated in an effort to provide a computational tool for optimum thermodynamic design. In the simulation, thermodynamic and heat transfer analysis was performed for the four major components : evaporator, condenser, compressor, and expansion valve. Effectiveness-NTU method was used for modeling both evaporator and condenser. The evaporator was divied into many subgrids and simultaneous cooling and dehumidifying analysis was performed for each grid to predict the performance accurately. Blance equations were used to model the compressor instead of using the compressor map. The performance of each component was checked against the measured data with CFC-12. Then, all the components were combined to yield the total system performance. Predicted cycle points were compared against the measured data with HFC-134a and the deviation was found to be less than 5% for all data. Finally, the system model was used to predict the performance of CFC-12 and HFC-134a for comparison. The results were very reasonable as compared to the trend deduced from the measured data.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.12
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• pp.75-81
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• 2008

A robust controller is proposed for regulating effectively the pressure of control cylinder of swash plate type variable displacement axial piston pump. In order to design a precise and robust pressure control system, a mathematical model for swash plate control system is identified by the signal compression method. Based on the identified mathematical model, an $H_{\infty}$ robust swash plate controller is designed which is robust to the variation of the load pressure. The precise and robust swash plate control characteristics are verified by experiments.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.3
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• pp.23-28
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• 2011

To secure basic data for intake port design, effects of a port masking on the part load performance were investigated in a 4 valve SI engine. For this purpose, 9 kinds of masking, which have different shapes and masking ratio, are applied to the engine intake system. The characteristics of the performance were estimated through mixture response test at various engine load and speed. The results show that NOx emission, one of indexes for stratification, increases considerably in spite of retarded spark timing due to the stratification which is caused by unequal flow distribution between the two intake ports. The mechanism of stratification by masking is different from axial stratification and the fuel entering through masked port plays a very important role in this stratification process. In conclusion, the port masking method could be easily applied to engine intake system and be very effective for inducing the stratified charging without the change of port design.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1109-1114
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• 2007

This paper presents the road simulator control technology for reproducing the road input signal to implement the real road data. The simulator consists of the hydraulic pump, servo valve, hydraulic actuator and its control equipment. The QFT is utilized to control the simulator effectively. The control system illustrates a tracking performance of the closed-loop controller with low order transfer function G(s) and pre-filter F(s) for a parametric uncertain model. A force controller is designed to communicate the control signal between simulator and digital controller. The efficacy of the QFT force controller is verified through the numerical simulation, in which combined dynamics and actuation of the hydraulic servo system are tested. The simulation results show that the proposed control technique works well under uncertain hydraulic plant system. The conventional software (Labview) is used to make up for the real controller in the real-time basis, and the experimental works show that the proposed algorithm works well for a single road simulator.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.1
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• pp.40-47
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• 2010

In this study, basic research on the thrust control by controling oxidizer mass flow rate of a $GO_2$/PE hybrid rocket is presented. For this purpose, hybrid rocket system including oxidizer flow control system and data acquisition system was developed. To control oxidizer mass flow rate, we used needle valve with stepping motor which was controled by LabVIEW program. During the fundamental experiments, this system managed to follow the pre-programmed (20 N - 10 N - 20 N - 0 N) thrust level.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.402-403
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• 2014

Micro-magnetic detection system is used to detect small particles in an automatic transmission valve body, which signal noise and time-delay may occurs in process of signal transmitting and filtering. In this paper, we present the design and implement of a micro-magnetic detection system based on wireless sensor networks. Micro-magnetic detection system consists of five modules which are magnetic sensor detector, signal processing unit, wireless sensor networks, system control unit and system monitoring unit. The experimental results show that signal noise and time-delay decreased.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.6
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• pp.447-460
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• 2012

In this study, the shutdown system of the fuel gas supply system is designed based on the Safety Integrity Level of IEC 61508 and IEC 61511. First of all, the individual risk($10^{-4}$/year) and the risk matrix which are the risk acceptance criteria are set up for the qualitative risk assessment such as the HAZOP study. The natural gas leakage at the gas supply pipe is identified as the highest risk among the hazards identified through the HAZOP study and as a safety instrumented function the shutdown function for leakage was defined. SIL 2 and PFD($2.5{\cdot}10^{-3}$) for the shutdown function are determined by the layer of protection analysis(LOPA). The shutdown system(SIS) carrying out the shutdown function(SIF) is verified and designed according to qualitative and quantitative requirements of IEC 61508 and IEC 61511. As a result of SIL verification and SIS conceptual design, the shutdown system is composed of two gas detectors voted 1oo2, one programmable logic solver, and two shutdown valve voted 1oo2.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.3
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• pp.213-219
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• 2015

Piezoelectric-based hydraulic actuator is a hybrid device consisting of a hydraulic pump driven by piezoelectric stacks that is coupled to a conventional hydraulic cylinder via a set of fast-acting valves. Nowadays, such hybrid actuators are being researched and developed actively in many developed countries by requirement of high performance and compact flight system. In this research, a piezoelectric hybrid actuator has been designed and tested. To achieve bi-directional capabilities in the actuator, solenoid valves were used to control the direction of output fluid. The experimental testing of the actuator in uni-directional and bi-directional modes was performed to examine performance issues related to the solenoid valves. The results showed that the bi-directional performance was slightly lower than uni-directional performance due to air bubble developed in the valve system. A new design to solve the vacuum problem has been proposed to improve the performance of the hybrid actuator.