• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.262-267
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• 2008

Numerical investigations were performed with an external-compression inlet with a three-dimensional bump at Mach 2 to scrutinize the geometrical effects of the bump in controlling the interaction of a shock wave with a boundary layer. The inlet was designed for two oblique shock waves and a terminal normal shock wave followed by a subsonic diffuser, with a circular cross-section throughout. The bump-type inlet that replaced the aft ramp of the conventional ramp-type inlet was optimized with respect to the inlet performance parameters as well as compared with the conventional ramp-type inlet. The current numerical simulations showed that a bump-type inlet can provide an improvement in the total pressure recovery downstream of the shock wave/boundary layer interaction over a conventional ramp-type inlet.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.262-267
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• 2008

Numerical investigations were performed with an external-compression inlet with a three-dimensional bump at Mach 2 to scrutinize the geometrical effects of the bump in controlling the interaction of a shock wave with a boundary layer. The inlet was designed for two oblique shock waves and a terminal normal shock wave followed by a subsonic diffuser, with a circular cross-section throughout. The bump-type inlet that replaced the aft ramp of the conventional ramp-type inlet was optimized with respect to the inlet performance parameters as well as compared with the conventional ramp-type inlet. The current numerical simulations showed that a bump-type inlet can provide an improvement in the total pressure recovery downstream of the shock wave/boundary layer interaction over a conventional ramp-type inlet.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.190-190
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• 2000

This paper presents a multirate state feedback control (MRSFC) method for systems sensitive to disturbance and noise based on the multirate estimator design using the current estimator. MRSFC updates the controller output slower than the measurement sampling frequency of system output by a lifting factor R=T$\sub$c//T$\sub$s/. The closed-loop MRSFC system is less sensitive to disturbance and noise due to filtering effect than the conventional single-rate control system. The multirate estimator gain is obtained from solving a conventional pole placement problem such that MRSFC has the same spectrum of eigenvalues in the s-plane as the single-rate control. We applied the proposed multirate state feedback controller to a galvanometer servo system. Simulation and experimental results show that settling and tracking performances are improved compared with a conventional single-rate pole placement control (PPC).

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2120-2122
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• 2002

There are several types of control systems that use fuzzy logic controller as a essential system component. The majority of research work on fuzzy PID controller focuses on the conventional two-input PI or PD type controller. However, fuzzy PID controller design is a complex task due to the involvement of a large number of parameters in defining the fuzzy rule base. In this paper we combined conventional PI type and PD type fuzzy controller and set the initial parameters of this controller from the conventional PID controller gains obtained by Ziegler-Nichols tuning or other coarse tuning methods. After that, by replacing some of these parameters with sing1e neurons and making them to be adjusted by back-propagation learning algorithm we designed a neuro-fuzzy controller which showed good performance characteristics in both computer simulation and actual application.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2161-2163
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• 2002

The PID type controller has been widely used in industrial application doc to its simply control structure, ease of design and inexpensive cost. However control performance of the PID type controller suffers greatly from high uncertainty and nonlinearity of the system, large disturbances and so on. This paper presents a hybrid fuzzy logic proportional plus conventional integral derivative controller (Fuzzy P+ID). In comparison with a conventional PID controller, only one additional parameter has to be adjusted to tune the Fuzzy P+ID controller. In this case, the stability of a system remains unchanged after the PID controller is replaced by the Fuzzy P+ID controller without modifying the original controller parameters. Finally, the proposed hybrid Fuazy P+ID controller is applied to BLDC motor drive. Simulation results demonstrated that the control performance of the proposed controlled is better than that of the conventional controller.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.3
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• pp.417-424
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• 2001

This paper proposes new symbol mapping method that can enhance the performance of trellis coded M-ary PSK compared with conventional symbol mapping methods in AWGN environment. Since the basic criteria of TCM design is Maximum Euclidean distance in AWGN, conventional symbol mapping method keep this basic criteria. In this paper, proposed new symbol mapping method uses both Euclidean distance and Hamming distance to design, while conventional methods make use of only optimal Euclidean distance. New symbol mapping method show the better BER performance than the other through computer simulation and error equations.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.11
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• pp.1-10
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• 1993

This paper proposes a High Performance Full-Swing BiCMOS (HiF-BiCMOS) circuit which improves on the conventional BiCMOS circuit. The HiF-BiCMOS circuit has all the merits of the conventional BiCMOS circuit and can realize full-swing logic operation. Especially, the speed of full-swing logic operation is much faster than that of conventional full-swing BiCMOS circuit. And the number of transistors added in the HiF-BiCMOS for full-swing logic operation is constant regardless of the number of logic gate inputs. The HiF-BiCMOS circui has high stability to variation of environment factors such as temperature. Also, it has a preamorphized Si layer was changed into the perfect crystal Si after the RTA. Remarkable scalability for power supply voltage according to the development of VLSI technology. The power dissipation of HiF-BiCMOS is very small and hardly increases about a large fanout. Though the Spice simulation, the validity of the proposed circuit design is proved.

• Korean Journal of Computational Design and Engineering
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• v.12 no.3
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• pp.182-192
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• 2007

The reduction of product development time is exposed to the competitive pressure due to shortened product-and production technology lifecycles as well as increasingly dynamic markets. Specially in automobile companies, that is of major importance for designing die because it is a bottleneck process in the development of a new car. To improve this conventional design process, this paper describes how to design it fast and flexibly. This was done by a modular method using standard template and a feature and knowledge based design method along the design process.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.516-521
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• 2002

This paper was reviewed technical items of catenary system for electrification of Gyeongbu(Dongdaegu∼Busan) and Honam(Daejeon∼Mokpo) conventional Railways. The lines have adopted new technical items in order to connect to Gyeongbu high speed railway. We can use the technology and experience of Gyeongbu and Honam lines to a new catenary system design up-graded for speed-up of conventional lines and new lines construction.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.528-530
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• 1999

This paper addresses the analysis and design of fuzzy control systems for a class of complex single input single output nonlinear systems. Firstly, the nonlinear system is represented by well-known Takagai-Sugeno (TS) fuzzy model and the global controller is constructed by compensating each linear model in the rule of TS fuzzy model. The design of conventional TS fuzzy-model-based controller usually is composed of two processes. One is to determine static state feedback gain of each local model and the other is to validate the stability of the designed fuzzy controller. In this paper, we propose an alternative of the design of TS fuzzy-model-based controller. The design scheme is based on the extension of conventional optimal control theory to the design of TS fuzzy-model-based controller. By using the proposed method the design and stability analysis of the TS fuzzy model-based controller is reduced to the problem of finding the solution of a set of algebraic Riccati equations. And we use the recently developed interior point method to find the solution of AREs, where AREs are recast as the LMI formulation. One simulation example is given to show the effectiveness and feasibility of the proposed fuzzy controller design method.