• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.84-91
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• 2001

In this study, the adaptive analysis procedure of crack propagation based on the element-free Galerkin(EFG) method is presented. The adaptivity analysis in quasi-static crack propagation is achieved by adding and/or removing the node along the background integration cell that are refined or recovered according to the estimated error. These errors are obtained basically by calculating the difference between the values of the projected stresses and original EFG stresses. To evaluate the performance of proposed adaptive procedure, the crack propagation behavior is investigated for several examples. The results of these examples show the efficiency and accuracy of proposed scheme in crack propagation analysis.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.452-459
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• 1999

In this study, error estimates using the stress projecting scheme and adaptive nodal generation procedure in the element-free Galerkin(EFG) method are proposed. The essence of proposed error estimates is to use the difference between the values of the projected stress and these given directly by the EFG solution. The stress projection can be obtained simply by taking product of shape function based on a different domain of influence with the stresses at nodes. An adaptive procedure based on error estimates is discussed in this paper. By use of background integration cell, adding node scheme at high error norm area is proposed. To demonstrate the performance of proposed scheme, the convergence behavior is investigated for several examples

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.1 s.232
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• pp.139-144
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• 2005

A vehicle cruise control algorithm using an Interacting Multiple Model (IMM)-based Multi-Target Tracking (MTT) method has been presented in this paper. The vehicle cruise control algorithm consists of three parts; track estimator using IMM-Probabilistic Data Association Filter (PDAF), a primary target vehicle determination algorithm and a single-target adaptive cruise control algorithm. Three motion models; uniform motion, lane-change motion and acceleration motion. have been adopted to distinguish large lateral motions from longitudinal motions. The models have been validated using simulated and experimental data. The improvement in the state estimation performance when using three models is verified in target tracking simulations. The performance and safety benefits of a multi-model-based MTT-ACC system is investigated via simulations using real driving radar sensor data. These simulations show system response that is more realistic and reflective of actual human driving behavior.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.667-673
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• 2000

A number of issues related with the vibrational behavior of pretwisted rotating beams featuring anisotropic properties and incorporating adaptive capabilities are considered in this paper. The adaptive capabilities are provided by a system of piezoactuators bonded or embedded into the structure. Based on the converse piezoelectric effect and on the out of phase activation, boundary control moments are pizoelectrically induced at the beam tip. A feedback control law relating the induced bending moments with the kinematical response quantities appropriately selected is used, and its beneficial effects, considered in conjunction with that of the beam anisotropy and structural pretwist upon the eigenvibration characteristics are highlighted

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.7
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• pp.752-765
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• 1999

대부분 병렬처리 시스템에서 성능 파라미터는 복잡하고 프로그램의 수행 시 예견할 수 없게 변하기 때문에 컴파일러가 프로그램 수행에 대한 최적의 성능 파라미터들을 컴파일 시에 결정하기가 힘들다. 본 논문은 병렬 처리 시스템의 프로그램 수행 시, 변화하는 시스템 성능 상태에 따라 전체 성능이 최적화로 적응하는 적응 수행 방식을 제안한다. 본 논문에서는 이 적응 수행 방식 중에 적응 프로그램 수행을 위한 이론적인 방법론 및 구현 방법에 대해 제안하고 적응 제어 수행을 위해 프로그램의 데이타 공유 단위에 대한 적응방식(적응 입도 방식)을 사용한다. 적응 프로그램 수행 방식은 프로그램 수행 시 하드웨어와 컴파일러의 도움으로 프로그램 자신이 최적의 성능을 얻을 수 있도록 적응하는 방식이다. 적응 제어 수행을 위해 수행 시에 병렬 분산 공유 메모리 시스템에서 프로세서 간 공유될 수 있은 데이타의 공유 상태에 따라 공유 데이타의 크기를 변화시키는 적응 입도 방식을 적용했다. 적응 입도 방식은 기존의 공유 메모리 시스템의 공유 데이타 단위의 통신 방식에 대단위 데이타의 전송 방식을 사용자의 입장에 투명하게 통합한 방식이다. 시뮬레이션 결과에 의하면 적응 입도 방식에 의해서 하드웨어 분산 공유 메모리 시스템보다 43%까지 성능이 개선되었다. Abstract On parallel machines, in which performance parameters change dynamically in complex and unpredictable ways, it is difficult for compilers to predict the optimal values of the parameters at compile time. Furthermore, these optimal values may change as the program executes. This paper addresses this problem by proposing adaptive execution that makes the program or control execution adapt in response to changes in machine conditions. Adaptive program execution makes it possible for programs to adapt themselves through the collaboration of the hardware and the compiler. For adaptive control execution, we applied the adaptive scheme to the granularity of sharing adaptive granularity. Adaptive granularity is a communication scheme that effectively and transparently integrates bulk transfer into the shared memory paradigm, with a varying granularity depending on the sharing behavior. Simulation results show that adaptive granularity improves performance up to 43% over the hardware implementation of distributed shared memory systems.

• Journal of KIISE:Software and Applications
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• v.31 no.8
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• pp.1073-1082
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• 2004

This paper presents a technique for an agent to adaptively behave to unforeseen and dynamic circumstances. Since the traditional methods utilized the information about an environment to control intelligent agents, they were robust but could not behave adaptively in a complex and dynamic world. A behavior-based method is suitable for generating adaptive behaviors within environments, but it is necessary to devise a hybrid control architecture that incorporates the capabilities of inference, learning and planning for high-level abstract behaviors. This Paper proposes a 2-level control architecture for generating adaptive behaviors to perceive and avoid dynamic moving obstacles as well as static obstacles. The first level is behavior-network for generating reflexive and autonomous behaviors, and the second level is to infer dynamic situation of agents. Through simulation, it has been confirmed that the agent reaches a goal point while avoiding static and moving obstacles with the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.758-762
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• 1994

Complicated dynamical behavior can occur in model reference adaptive control systems when two external sinusoidal signals are introduced although the plant and reference model are stable linear first older systems. The phase portrait plot and the power spectral analysis indicate chaotic behavior. In the system treated, a positive Lyapuniov exponent and non-integer dimension clearly manifest chaotic nature of the system.

• Journal of Advanced Navigation Technology
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• v.10 no.1
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• pp.70-78
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• 2006

This paper has addressed the scheme to design single rate Rate Adaptive Shaper (srRAS) proposed in RFC2963. srRAS is the shaper used in conjugation with downstream single rate Three Color Marker (srTCM) described in RFC269. it is tail-drop First Input First Out (FIFO) queue that is drained at a variable rate. srTCM meters IP packet streams from srRAS and marks its packets to be either green, yellow, or red. This shaper has been proposed to use at the ingress of differentiated services networks providing AF PHB. And then srRAS can reduce the burstiness of the upstream traffic of srTCM. This paper addresses algorithm, architecture of srRAS, and the scheme to implement srRAS using Field-Programmable Gate Arrays (FPGA) and the related technology.

• Journal of The Korean Association of Information Education
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• v.2 no.2
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• pp.201-208
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• 1998

Recently software complexity will continue to increase dramatically in the coming decades because of the dynamic and distributed nature of both data and applications. Not only must software systems assist in coordinating tasks among humans, they must also help mannage cooperation among distributed programs. Software agent may properly respond to these requirements. This paper investigates the adaptive characteristics found in adaptive tutoring agents. To funcion effectively throughout the range of situations presented by such a dynamic and extremely-distributed information entities, an agent must be highly adaptive. Adaptivity exists in several key aspects of agent's behavior to its dynamic situation. My goal is to show the various aspects of internal adaptivity that could be applied to build comprehensive agents that function effectively in tutoring agent system.

• 한국생물공학회:학술대회논문집
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• 2004.07a
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• pp.47-84
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• 2004

Principal Component Analysis나 Partial Least Squares와 같은 다변량 통계 기법은 변수간의 correlation structure로부터 공정의 variance를 설명할 수 있는 latent variable를 얻고 이를 이용하여 공정을 효과적으로 modeling할 수 있는 방법으로 최근 들어 많은 관심을 얻고 있다. 하지만 PLS는 공정이 stationary state에 있다고 가정하기 때문에, 생물학적 공정의 non-stationary and time-varying behavior를 설명하기에 부적절하다. 본 논문에서는 PLS 알고리즘의 혐기성 폐수처리 공정에의 적용에 있어, 이와 같은 문제를 해결하기 위해서 adaptive PLS 알고리즘을 사용함으로써 변화하는 공정의 특성에 대응하여 모델을 update하는 방법을 이용하였다. 하지만 실시간 데이터로부터 adaptive PLS 방법을 적용하는 데에는 많은 어려움이 존재하며, 특히 outlier나 abnormal disturbance에 모델이 부적절하게 adaptation하는 문제가 발생할 수 있다. 따라서 이의 해결을 위해 adaptive PLS를 적용하는데 있어 robustness를 향상시키기 위해 monitoring index를 이용하여 abnormal data에 weight를 주고 안정적인 모델의 update가 가능하게 하는 방법을 제안하였으며, 이를 적용하여 성공적으로 혐기성 폐수처리 공정의 Output을 예측하고 효과적으로 공정을 모니터링할 수 있었다. 만들어진 PLS 모델은 산업폐수를 처리하기 위한 industrial plan에서 측정된 실제 데이터에 적용하여 그 효용성을 입증하였으며, 그 결과는 mechanistic model을 적용하기 힘든 실공정에 비교적 쉽게 implementation할 수 있는 장점이 있다.