• Journal of Advanced Marine Engineering and Technology
• /
• 제32권6호
• /
• pp.955-963
• /
• 2008

In this paper, we propose an improved practical encryption and fault-tolerance decryption method using a non-negative value key and random function obtained with a white noise by using iterative phase wrapping method. A phase wrapping operating key, which is generated by the product of arbitrary random phase images and an original phase image. is zero-padded and Fourier transformed. Fourier operating key is then obtained by taking the real-valued data from this Fourier transformed image. Also the random phase wrapping operating key is made from these arbitrary random phase images and the same iterative phase wrapping method. We obtain a Fourier random operating key through the same method in the encryption process. For practical transmission of encryption and decryption keys via Internet, these keys should be intensity maps with non-negative values. The encryption key and the decryption key to meet this requirement are generated by the addition of the absolute of its minimum value to each of Fourier keys, respectively. The decryption based on 2-f setup with spatial filter is simply performed by the inverse Fourier transform of the multiplication between the encryption key and the decryption key and also can be used as a current spatial light modulator technology by phase encoding of the non-negative values. Computer simulations show the validity of the encryption method and the robust decryption system in the proposed technique.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2002년도 추계학술대회 논문집
• /
• pp.68-72
• /
• 2002

Localization with array sensors has been applied for not only military but also non-military purposes. The identification of submarines and fish finding are those examples. Nowadays the demand for noise identification is increasing to characterize noise sources and improve acoustic performance of underwater acoustic equipment. For that reason KRISO/KORDI recently constructed an anechoic basin which bus reflection only at the free surface. This paper suggests a noise identification methods using MUSIC algorithm in such an acoustic field. For comparison phase delay sum and minimum valiance methods are also described. At first basic principles are described. A several numerical simulations are also performed. The results say that reflection effect many cause a new non-real source although good estimation is obtained under no reflection conditions.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.1862-1866
• /
• 2003

A control system design with Coefficient Diagram Method (CDM) is proven that effective for SISO control design. But the control system design for MIMO via CDM is not concrete procedure. In this paper presents the control system design method for quadruple-tank process via CDM. By using the decentralized method for both non-minimum phase and minimum phase are made. The results from Integral-Proportional (I-P) controller’s design via CDM and standard Proportional-Integral (PI) controls are also shown to compare the merits of the proposed controllers.

• 대한전기학회논문지
• /
• 제37권11호
• /
• pp.720-726
• /
• 1988

본 논문에서는 적응 알고리즘을 마이크로컴퓨터에 의하여 실현하고 그것을 열교환기에 응용하였으며 실험결과 검토하엿다. 실험을 위하여 제작된 열교환기는 비최소위상 시스템으로 판정되었으며 직접 수확적으로 모형화하는 데에는 많은 어려움이 있었다. 따라서 PID제어방법 등 다른 고전적인 제어 방법들을 사용하려면 실험을 통한 많은 시행착오를 거쳐 시스템의 파라미터 값들을 결정해야하고 시스템의 파라미터 값들이 변화할 경우 좋은 성능을 보장하지 못한다. 이런 어려움을 극복하고 제어기의 성능을 향상시키기 위해 비최소상위 시스템에 적용할 수 있는 두 가지 적응제어 방식을 선택하여 열교환기에 응용하여 보았다. 아울러 적응제어 방식의 성능을 종래의 PID제어기에 의한 결과와 비교하여 보았다.이러한 연구의 최종적인 목적은 산업플랜트에 손쉽게 적용될 수 있는 제어기를 마이크로프로세서를 사용하여 구성하는 것이다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제27권3호
• /
• pp.388-394
• /
• 2003

Hydraulic system is difficult to obtain a suitable performance due to the nonlinearity load pressure change and system parameter variation. The requirement of control a1gorithm has been complex in order to satisfy the performance. The adaptive control is a control method which is suggested to achieve the control object under the plant characteristics change. In spite of the case that plant characteristics and the degree of variation are difficult to grasp. the adaptive control could keep the characteristics of closed-loop system generally. In this study. a method of combined generalized minimum variance adaptive control (GMVAC) and output error feedback is proposed, in order to solve the problem of non-minimum phase of plant and the vibration and overshoot in initial response. The control performance according to the variation of characteristics of plant is evaluated by changing the supply pressure. The experimental results show the effectiveness of the proposed scheme.

• 전자공학회논문지SC
• /
• 제38권3호
• /
• pp.1-12
• /
• 2001

본 논문은 파라미터 불확실성을 갖는 비최소위상 시스템의 강인제어 문제를 고려한다. 먼저 불확실성을 갖는 비최소위상 시스템을 구간 최소위상 전달함수군과 Pade'근사화 형태로 시간지연 성분으로 변환하는 새로운 방법을 제시한다. 제안하게 될 제어기는 비최소위상 플랜트로 인한 시간지연 거동을 보상할 수 있도록 Smith 예측기 구조를 갖는 보상기로 구성된다. 최소위상 플랜트군의 피드백 제어기는 구조적 불확실성에 대해 주파수 영역의 설계사양의 강인 안정도를 만족하도록 QFT를 이용하여 설계되었다. 전체 시스템의 안정도와 성능은 예제를 통하여 입증한다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
• /
• pp.383-387
• /
• 1989

In this paper, an adaptive algorithm for processes with unmeasured deterministic disturbances is presented. This algorithm is simple to synthesize an adaptive controller with desired pole/zero assignment. The internal stability requirement is achieved so that this algorithm can easily handle any minimum or non-minimum phase system. Some simulations are given to show the applicability of this approach.

• Journal of Power Electronics
• /
• 제16권4호
• /
• pp.1396-1406
• /
• 2016

A novel controller design is presented for the recently proposed electric springs (ESs). The dynamic modeling is analyzed first, and the initial Bode diagram is derived from the s-domain transfer function in the open loop. The design objective is set according to the characteristics of a minimum phase system. Step-by-step optimizations of the Bode diagram are provided to illustrate the proposed controller, the design of which is different from the classical multistage leading/lagging design. The final controller is the accumulation of the transfer function at each step. With the controller and the recently proposed δ control, the critical load voltage can be regulated to follow the desired waveform precisely while the fluctuations and distortions of the input voltage are passed to the non-critical loads. Frequency responses at any point can be modified in the Bode diagram. The results of the modeling and controller design are validated via simulations. Hardware and software designs are provided. A digital phase locked loop is realized with the platform of a digital signal processor. The effectiveness of the proposed control is also validated by experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• 제5B권4호
• /
• pp.331-336
• /
• 2005

With increasing emphasis on non-conventional energy systems and autonomous power generation, development of improved and appropriate generating systems has recently taken on greater significance. This paper describes the performance analysis of a single phase self-excited induction generator (SEIG), suitable for autonomous/standby power systems. The system is also appropriate for wind energy systems and small portable systems. Both windings of the induction machine, the main and the auxiliary, are utilized. One winding will be devoted to the supply excitation current only, by being connected to the excitation capacitor, while the load is connected across the other winding. As the design of excitation, the minimum of self-excited capacitor connected auxiliary winding is determined as the suitable value using a circuit equation of auxiliary winding. For the steady state analysis, the equivalent circuit of the single-phase induction generators is used as a basis for modeling using the double-revolving field theory. The validity of the designed generator system is confirmed by experimental and computed results.

• 제어로봇시스템학회논문지
• /
• 제2권1호
• /
• pp.14-20
• /
• 1996

This paper presents a self tuning method of a velocity type PID controller for minimum or non-minimum phase systems with time delays. The velocity type PID control structure is determined in the process of minimizing the variance of the auxilliary output, and self tuning effect is achieved through the recursive least square algorithm at the parameter estimation stage and also through the Robbins-Monro algorithm at the stage of optimizing a design parameter. This method is simple and effective compared with other existing methods[1,2]. Numerical examples are included to illustrate the procedure and to show the performance of the control system.