• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.261-264
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• 1992

In designing the fuzzy rule-based system, it has effected by the four significant factors such as the choice of membership function, scaling factor, the numbers of fuzzy control rule, the method of defuzzification. In this paper we design the fuzzy rule based system and evaluate by three factors, as followes reaching time, overshoot, and amplitude. And then we wiII show that the significant factors are the choice of scaling factor and the numbers of fuzzy control rule, and the system performance can be improved by the proper selection of the scaling factors.

• 한국항만학회지
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• 제15권1호
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• pp.37-46
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• 2001

Fuzzy logic control(FLC) is composed of three parts : fuzzy rule-bases, membership functions, and scaling factors. Well-defined fuzzy rule-base should contain proper physical intuition on the plant, so are needed lots of experiences of the skillful expert. When membership functions are considered, some parameters on the memberships function such as function shape, support, allocation density should be selected well. The rule of scaling factors is 'scaling'(amplifying or reducing) for both input and output signals of the FLC to fit in the membership function support and to operate the plant intentionally. To get a better performance of the FLC, it is necessary to adjust the parameters of the FLC. In general, the adaptation of the scaling factors is the most effective adjustment scheme, compared with that of the fuzzy rule-base or membership function parameters. This study proposes the adaptation scheme of the scaling factors. When the adaptation is performed on-line, the stability of the adaptive FLC should be guaranteed. The stable FLC system can be designed with stability analysis in the sense of Lyapunov stability. To adapt the scaling factors for the error signals, the concept of the conventional MRAC would be introduced into slightly modified form. A tracking accuracy of the control system would be enhanced by the modified shape and support of the membership function. The simulation is achieved on the pilot plant with the hydraulic steering control of a UCT(Unmanned Container Transporter) of which modeling dynamics have lots of severe uncertainties and modeling errors.

• 전기학회논문지
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• 제57권9호
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• pp.1618-1623
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• 2008

In this paper, a new design method for IMC-PID that adds a phase scaling factor of system identifications to the standard IMC-PID controller as a control parameter is proposed. Based on analytically derived frequency properties such as gain and phase margins, this tuning rule is an optimal control method determining the optimum values of controlling factors to minimize the cost function, integral error criterion of the step response in time domain, in the constraints of design parameters to guarantee qualified frequency design specifications. The proposed controller improves existing single-parameter design methods of IMC-PID in the inflexibility problem to be able to consider various design specifications. Its effectiveness is examined by a simulation example, where a comparison of the performances obtained with the proposed tuning rule and with other common tuning rules is shown.

• 산업기술연구
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• 제20권B호
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• pp.155-162
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• 2000

Although Fuzzy Logic Controller(FLC) adopted three terms as input gives better performance, FLC is in general composed of two-term control because of the difficulty in the construction of fuzzy rule base. In this paper, a three-term FLC which is similar to PID control but acts as a nonlinear controller is proposed. To reduce the complexity of the rule base design and to increase efficiency. a simplified fuzzy PID control is induced from a hybrid velocity/position type PID algorithm by sharing a common rule base for both fuzzy PI and fuzzy PD parts. It is simple in structure, easy in implementation, and fast in calculation. The phase plane technique is applied to obtain the rule base for fuzzy two-term control and the resultant rule base is Macvicar-Whelan type. And the membership function is a Gaussian function. The frequency response information is used in tuning of the membership functions. Also a tuning strategy for the scaling factors is proposed based on the relationship between PID gain and the scaling factors. Simulation results show better performance and the effectiveness of the proposed method.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권1호
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• pp.92-97
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• 2008

In this Paper, we present a scaling theory for dual material surrounding gate (DMSGTs) MOSFETs, which gives a guidance for the device design and maintaining a precise subthreshold factor for given device parameters. By studying the subthreshold conducting phenomenon of DMSGTs, the effective conductive path effect (ECPE) is employed to acquire the natural length to guide the design. With ECPE, the minimum channel potential is used to monitor the subthreshold behavior. The effect of ECPE on scaling factor significantly improves the subthreshold swing compared to conventional scaling rule. This proposed model offers the basic designing guidance for dual material surrounding gate MOSFETs.

• Journal of electromagnetic engineering and science
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• 제13권2호
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• pp.127-133
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• 2013

We examined the scaling effects of a number of gate_fingers (N) and gate_widths (w) on the high-frequency characteristics of $0.1-{\mu}m$ metamorphic high-electron-mobility transistors. Functional relationships of the extracted small-signal parameters with total gate widths ($w_t$) of different N were proposed. The cut-off frequency ($f_T$) showed an almost independent relationship with $w_t$; however, the maximum frequency of oscillation ($f_{max}$) exhibited a strong functional relationship of gate-resistance ($R_g$) influenced by both N and $w_t$. A greater $w_t$ produced a higher $f_{max}$; but, to maximize $f_{max}$ at a given $w_t$, to increase N was more efficient than to increase the single gate_width.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.213-217
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• 2008

본 논문에서는 표준 IMC-PID 제어기에 시스템 식별상의 위상 조절 인자를 설계 변수로 추가함으로 새로운 IMC-PID 제어기 설계 방법을 제안한다. 제안된 제어기의 동조법으로 해석적으로 구해진 주파수 영역 특성을 통해 주파수 영역 성능을 보장하도록 하는 설계 변수의 구속 조건 하에서 시간영역의 적분 오차 지표를 가격함수로 최소화하는 최적 해를 얻는다. 이 제안된 동조법은 다양한 설계 사양을 동시에 고려하도록 하여 기존의 IMC-PID의 단일 설계 변수 동조가 갖는 비유연성 문제를 개선하였다. 사례 연구에서 기존의 동조법들과의 성능 비교를 통해 그 유용성을 검토했다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 D
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• pp.650-652
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• 2000

Although Fuzzy Logic Controller(FLC) adopted three terms as input gives better performance. FLC is in general composed of two-term control because of the difficulty in the construction of fuzzy rule base. In this paper, a three-term FLC which is similar to PID control but acts as a nonlinear controller is proposed. To reduce the complexity of the rule base design and increase efficiency, a simplified fuzzy PID control is induced from a hybrid velocity/position type PID algorithm by sharing a common rule base for both fuzzy Pi and fuzzy PD parts. It is simple in structure, easy in implementation, and fast in calculation. The phase plane technique is applied to obtain the rule base for fuzzy two-term control and them. The resultant rule base is Macvicar-Whelan type. The frequency response information is used in tuning of membership functions. Also a tuning strategy for the scaling factors is Proposed based on the relationship between PID gain and them. Simulation results show better performance and the effectiveness of the proposed method.

• 한국항공우주학회지
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• 제43권12호
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• pp.1089-1096
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• 2015

해상 운용 헬리콥터는 비상부주를 적용하여 탑승자의 안전한 탈출을 위해 일정시간 이상 안정된 상태를 유지할 수 있어야 한다. 규정에서도 헬기가 해상에 착륙 후 승객이 탈출할 수 있는 충분한 부양시간을 요구하고 있다. 이를 위해 국내개발 헬기의 비상부주 장비는 해수면에서의 안정성 입증을 위해 "Froude Scaling" 기법을 적용하여 수조시험을 수행하였다. 시험 형상 및 조건은 헬기 하중조건과 요구되는 규격을 고려하여 설정하였다. 시험결과 요구 조건인 해상 상태 코드4와 손상조건 해상 상태 코드2에서 안전성이 있음을 확인하였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제6권4호
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• pp.234-239
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• 2006

In the past decade, several tools have been developed to automate the floating-point to fixed-point conversion for DSP systems. In the conversion process, a number of scaling shifts are introduced, and they inevitably alter the original code sequence. Recently, we have observed that a compiler can often be adversely affected by this alteration, and consequently fails to generate efficient machine code for its target processor. In this paper, we present an optimization technique that safely migrates scaling shifts to other places within the code so that the compiler can produce better-quality code. We consider our technique to be safe in that it does not introduce new overflows, yet preserving the original SQNR. The experiments on a commercial fixed-point DSP processor exhibit that our technique is effective enough to achieve tangible improvement on code size and speed for a set of benchmarks.