• 한국기계가공학회지
• /
• 제14권1호
• /
• pp.78-84
• /
• 2015

The stress state acting on mechanical parts and structures is generally mixed stress. This complex stress state, which is subject to changes in the environment, will produce many. Cars running on roads with different road conditions will subject the automotive parts to combined stress state. In the x direction and the y direction, a different amplitude and frequency of the fatigue load can be present. However, the load amplitude for Mode I and Mode II in a 2-axis fatigue test is limited to a constant ratio; the load frequency is always the same for any mode. In this paper, it is verified how the variation of the load frequency for mode II affects the behavior of fatigue crack propagation under mixed mode.

• 제어로봇시스템학회논문지
• /
• 제13권1호
• /
• pp.15-18
• /
• 2007

We consider the problem of designing a static output feedback sliding mode control law for linear dynamical systems with mismatched uncertainties in the state matrix. We assume that an output dependent sliding surface guaranteeing the quadratic stability of the sliding mode dynamics is given, the reachability condition is not required to be satisfied globally, and the output feedback sliding mode control law complises both linear and discontinuous parts. We reduce the problem of designing the linear part of the sliding mode control law to a simple LMI problem which offers design flexibility for combining various useful convex design specifications. Our approach does not require state transformation and it can be applied to mismatched uncertain systems.

• 대한전자공학회논문지
• /
• 제21권1호
• /
• pp.1-6
• /
• 1984

기하광학적 해석방법으로 입사조건에 따른 SCS(step-graded-step) 모드 스크램블러의 near field pattern, 모달 파우어 분포 및 far field pattern을 계산하고, 실험결과와 일치함을 보였다. 이로부터 SGS 모드 스크램블러에 의해 피측정 graded index 광섬유에서 stable mode launching이 이루어짐을 설명하였다. 또한 SGS 모드 스크램블러의 효과적 사용 방법으로는 입사 NA를 적게하는 것이 좋다는 것을 알았으며, 실험으로 확인하였다.

• 한국자동차공학회논문집
• /
• 제21권1호
• /
• pp.78-85
• /
• 2013

This paper presents the sliding mode control methods for anti-lock brake system (ABS) with the friction force observer. Using a simplified quarter car model, the sliding mode controller for ABS is designed to track the desired wheel slip ratio. Here, new method to find the desired wheel slip ratio which produces the maximum friction force between road and tire is suggested. The desired wheel slip ratio is varying according road and tire conditions to produce maximum friction force. In order to find optimum desired wheel slip ratio, the sliding mode observer for friction force is used. The proposed sliding mode controller with observer is evaluated in simulation, and the control design is shown to have high performance on roads with constant and varying adhesion coefficients.

• 제어로봇시스템학회논문지
• /
• 제1권1호
• /
• pp.25-32
• /
• 1995

Nonlinear depth control algorithms for the hovering system of underwater vehicles are presented. In this paper, a nonlinear effect in heave motion for underwater vehicles, a deadzone effect of the flow control valve in the hovering tank and an impact disturbance are considered. In this situation, in order to choose a desirable controller, sliding mode controller and fuzzy sliding mode controller are designed and compared. The computer simulation results show that the fuzzy sliding mode control system is more suitable in order to maintain a desirable depth of an underwater vehicle with a deadzone and impact disturbance.

• Smart Structures and Systems
• /
• 제25권1호
• /
• pp.37-45
• /
• 2020

This paper aims at enlightening the properties, computational and implementation issues related to Kalman filter based state estimation algorithms and sliding mode observers, by applying them for estimating the states of a smart structure system. The Kalman based estimators considered in this work are Kalman filter and information filter and, the sliding mode observers considered are Utkin observer and higher order sliding mode observer. A fourth order linear time invariant model of a piezo actuated beam is used in this work. This structure is embedded with four number of piezo patches, of which two act as sensors, one as disturbance actuator and the other as control actuator. The performance of the state estimation algorithms is evaluated through simulation, for the first two vibrating modes of the piezo actuated structure, when the structure is maintained at first mode and second mode resonance.

• 한국기계가공학회지
• /
• 제5권3호
• /
• pp.36-42
• /
• 2006

The analytical realization of uncoupled system was introduced in this study using times series and its spectrum analysis. The ARMAX spectra of time series methods were compared with the conventional FFT spectrum. Also, the response of second order system uncoupled was solved using the Runge-Kutta Gill method. In this numerical analysis, the displacement, velocity and acceleration were calculated. The displacement response among them was used for the power spectrum analysis. The ARMAX algorithm in time series was proved to be appropriate for the mode estimation and spectrum analysis. Using the separate response of first and second mode, each modes were calculated separately and the response of mixed modes was also analyzed for the mode estimation using several time series methods.

• 한국전기전자재료학회논문지
• /
• 제15권1호
• /
• pp.37-45
• /
• 2002

We described a method of resonant mode identification in dielectric-disc loaded cylindrical cavity resonators. The characteristic equations are solved using the ContourPlot graph of Mathematica. Contour graph method uses graphical method. It is comparable with numerical method. The numerical method is very difficult mode identification. The analysis is based on the approximated electromagnetic representation which is only concentrated on the calculation of resonant frequencies, and a mode identification of resonant frequencies has not been covered. However, It is possible to calculate precise resonant frequencies and to identify the mode of resonant frequencies using the contour graph method. The contour graph method is not a method using approximated representation of electromagnetic field variation at the outer area of dielectric in the resonators. It is a method using enact representation.

• Current Optics and Photonics
• /
• 제7권6호
• /
• pp.708-713
• /
• 2023

A robust all-fiber nonlinear amplifying loop-mirror-based mode-locked femtosecond laser is demonstrated. Power-dependent nonlinear phase shift in a Sagnac loop enables stable and power-efficient mode-locking working as an artificial saturable absorber. The pump power is adjusted to achieve the lowest intensity noise for stable long-term operation. The minimum pump power for mode-locking is 180 mW, and the optimal pump power is 300 mW. The lowest integrated root-mean-square relative intensity noise of a free-running mode-locked laser is 0.009% [integration bandwidth: 1 Hz-10 MHz]. The long-term repetition-rate instability of a free-running mode-locked laser is 10^-7 over 1,000 s averaging time. The repetition-rate phase noise scaled at 10-GHz carrier is -122 dBc/Hz at 10 kHz Fourier frequency. The demonstrated method can be applied as a seed source in high-precision real-time mid-infrared molecular spectroscopy.

• 한국자동차공학회논문집
• /
• 제25권1호
• /
• pp.116-126
• /
• 2017

We suggest a process for the basic software configurations and application development in the mode management design of AUTOSAR-based ECU. Mode management is an essential task and AUTOSAR provides the mode management components for the runtime state handling of an ECU, such as BswM, application mode manager and RTE. BswM is used to meet the custom's requirements for ECU state handling. The behavior of BswM is configured with a set of rules in the form of "if-else" statements, so it is a complicated job and a potential source of errors as the number of rules increases. These difficulties can be overcome using the Model-Based Development approach, which is widely used in the AUTOSAR SW development. An efficient process is proposed to apply the MBD approach to the BswM configuration. An application mode development process is also proposed to improve the mode management design by combining the MBD process. Development tools are developed to adapt these proposed processes to the traditional ones. Simulation and experimental results are provided to prove the feasibility of the proposed approach.