• International Journal of Knowledge Content Development & Technology
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• v.10 no.2
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• pp.7-18
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• 2020

Communication is a process involving a group of interrelated elements working together for the purpose of information transfer. This paper discusses information retrieval as a communication process in the 21st century library. The difficulties associated with access to recorded knowledge through bibliographic control devices have been exacerbated by the interposition of additional encoding processes in the library and further decoding by the users. In addition, the innovation of internet/web has revolutionized the means and mode of communication process in the library by flooding information seekers with information and creating an illusion of self-sufficiency in many users. With these changes in information seeking behaviour and pattern, a cybernetic approach to information retrieval has emerged emphasizing adaptive control mechanisms and feedback processes. This paper argues that libraries should strive to continuously remain relevant by keeping abreast with changes in the behavior of information users. To this end, this paper proposes apomediatic-cybernetic model of communication, which illustrates information retrieval processes for the 21st-century library.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.653-661
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• 1994

In this paper the CSCM type upwind flux difference splitting Navier-Stokes method has been applied to study the ARL-SL19 supersonic/transonic compressor cascade flow. H-type grid was chosen for its simplicity in applying cyclic tridiagonal matrix algorithm along with conventional slip/no-slip boundary conditions. The thin-layer algebraic model of Baldwin-Lomax was employed for the calculation of turbulent flows. The test case inlet Mach No. was 1.612 and inlet/exit pressure ratio($P_2/P_1$) was 2.15. The results were compared with experimental results from current method were compared well in suction surface with the experiments and other computational results; however, not well in pressure surface. It might be due to the complex flowfields such as shock/boundary layer interaction, turbulence, and flow separation, etc. In the future, a proper turbulence modelling and adaptive grid system will be studied to improve the solution quality.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.135-138
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• 2006

지능형 홈 네트워크 기술에 대한 도입으로 인해 인간뿐만 아니라 사물들도 컴퓨팅 및 커뮤니케이션 능력을 가지고 주변 상황을 인식하고 판단하여 인간에게 유용한 서비스를 제공하게 될 것이다. 그러나 현 실정에 있어 홈 네트워크 서비스는 단순한 가전기기 제어 관련 서비스만을 제공하고 있다. 다양하게 변화하는 상황에 맞는 상황 적응적 서비스를 제공해야 하는 본 취지에 맞는 서비스를 제공하지 못하고 있다. 따라서 본 논문에서는 사용자의 행위에 규칙성에 기반을 두며, 사용자 행위를 예측하여 지능적으로 동작할 수 있는 근거를 마련할 수 있는 능동적인 서비스를 제공할 수 있는 지능형 제어 모델을 제안하고자 한다.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.140-143
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• 1991

This paper describes a compensation method for the rotor resistance variation of induction machines in speed sensor-less vector control system using MRAS(model reference adaptive system). In case of rotor resistance variation, the analysis of the conventional speed sensor-less vector control system using MRAS is presented and the compensation method for rotor resistance variation using Fuzzy logic is proposed. In order to confirm the performance of the proposed algorithm, computer simulation is performed.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.148-151
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• 1991

This paper describes the vector control system estimates rotor speed based on MRAS(Model Reference Adaptive Control) and this estimate is used for speed feedback control. The stability of speed estimator is proved on the basis of hyperstability theory. In order to improve the performance of speed control, the load torque is estimated by load torque observer and speed controller compensates this estimate value. Thus the robust vector control system against load torque disturbance is constructed.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.12
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• pp.1520-1526
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• 1999

This paper presents a current feedback learning controller for dynamic control of DC motors. The proposed controller uses the full third-order dynamics model of DC motor system to drive stable learning rules for virtual current learning input, voltage learning input, and the coefficient of electromotive force. It is shown that the proposed learning controller drives the state of uncertain DC motor system with unknown system parameters and external load torque to the desired one globally asymptotically. Computer simulation and experimental results are given to demonstrate the effectiveness of the proposed adaptive learning controller.

• Proceedings of the Korea Database Society Conference
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• 1999.06a
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• pp.281-287
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• 1999

Decision class analysis (DCA) is viewed as a classification problem where a set of input data (situation-specific knowledge) and output data (a topological leveled influence diagram (ID)) is given. Situation-specific knowledge is usually given from a decision maker (DM) with the help of domain expert(s). But it is not easy for the DM to know the situation-specific knowledge of decision problem exactly. This paper presents a methodology fur sensitivity analysis of DCA under incomplete information. The purpose of sensitivity analysis in DCA is to identify the effects of incomplete situation-specific frames whose uncertainty affects the importance of each variable in the resulting model. For such a purpose, our suggested methodology consists of two procedures: generative procedure and adaptive procedure. An interactive procedure is also suggested based the sensitivity analysis to build a well-formed ID. These procedures are formally explained and illustrated with a raw material purchasing problem.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.13-16
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• 1996

A new instantaneous torque control technique is presented for a high performance control of a permanent magnet synchronous motor. Using the model reference adaptive system technique, the linkage flux of the motor is estimated and the torque is instantaneously controlled by the proposed torque controller combining with a variable structure control and space vector PWM. The proposed torque control provides the advantage of reducing the torque pulsation caused by the flux harmonics. This control strategy is applied to the high torque PM synchronous motor drives for direct drive systems and is implemented by using a software of the DSP TMS320C30. The experiments are carried out for this system and the results well demonstrate the effectiveness of the proposed control.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.443-447
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• 2001

In this paper, a robust sensorless vector control system for induction motors with a speed estimator and an uncertainty observer is presented. At first, the proposed speed estimator is based on the MRAS(Mode Reference Adaptive System) scheme and constructed with a simple fuzzy logic(FL) approach. The structure of the proposed FL estimator is very simple. The input of the FL is the rotor flux error difference between reference and adjustable model, and the output is the estimated incremental rotor speed Secondly, the unmodeled uncertainties such as parametric uncertainties and external load disturbances are modeled by a radial basis function network(RBFN). In the overal speed control system, the control inputs are composed with a norminal control input and a compensated control input, which are from RBFN observer output and the modeling error of the RBFN, repectively. The compensated control input is derived from Lyapunov unction approach. The simulation results are presented to show the validity of the proposed system.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.382-385
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• 2007

본 논문에서는 다중 표적의 중첩이라는 상황에 대한 새로운 해결 방식을 소개한다. 비선형 표적의 위치와 속도에 대한 추적을 중심으로 표적과 비표적의 중첩이 일어나는 순간 이후 분리되었을 때 추적중인 표적을 지속적으로 유지할 수 있는 방법에 대해 이야기 하고자 한다. 이 논문에서 제안된 알고리즘은 예측 명중위치 개념과 최대 잡음수준을 이용한 칼만필터 기반의 적응 상호작용 다중모델 기법으로 측정된 위치값과 예측된 명중위치 사이의 차이를 고려한 변형된 칼만필터 개념을 이용한다. 이 논문에서는 비선형 표적의 가속도를 시변 변수인 표적의 추가적인 잡음으로 두고 각각의 가속도 간격의 정도에 따라 얻어지는 모든 잡음에 대한 변수에 의해 각각의 하부 모델들을 특성화시켰다. 제안된 알고리즘은 표적의 운동특성에 따라 적응적으로 기법을 선택할 수 있는 선택적 방식을 구현하고자 한다. 표적의 기동중에 나타나는 가속도를 효과적으로 다루기 위하여 잡음의 크기가 급격히 증가하는 경우 그 증가분을 가속도로 인식하여 기동표적 관계식에 이용한다. 그리고 제안된 알고리즘의 수행 가능성을 보여주기 위하여 몇 가지 예를 제시하였다.