• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.10
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• pp.840-845
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• 2012

An ARX(Auto-Regressive eXogenous) modeling technique for vortex dynamics in the BFS(Backward Facing Step) flow field is proposed in this paper. In order for the modeling of the dynamics, the spatial and temporal modes are extracted through POD(Proper Orthogonal Decomposition) analysis. Determining the orders of the inputs and outputs for an ARX structure is carried out by the spectrum analysis and temporal mode analysis, respectively. The order of input delay terms is also determined by the flow velocity. Finally the coefficients of the ARX model are designed by using an artificial neural network.

• Herbal Formula Science
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• v.30 no.3
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• pp.109-121
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• 2022

Objective : This study is conducted to investigate the effect of Astragali Radix on Post Traumatic Stress Disorder(PTSD) induced by the Single Proposed Stress(SPS). Methods : The experiment was conducted with five groups; SAL groups with only saline treatment, SPS group, SPS + ARX25 group, SPS + ARX50 group, and SPS + ARX100 group. After applying SPS, saline and ARX were administered for 14 days to identify the change of body weight, sucrose intake amount, and behavioral changes through Open Field Test(OFT) and Forced Swimming Test(FST). After the behavioral experiment, plasma corticosterone levels, serotonin, norepinephrine and dopamine concentrations were measured by enzyme-linked immunoassay in medical prefrontal cortex, hippocampus, and amygdala. Brain-derived neurotrophic factor(BDNF) in the hippocampus was measured using Reverse Transcription Polymerase Chain Reaction. Results : Weight change has significantly decreased in the SPS group compared to the SAL group(p<0.05). On day 14, the sucrose intake of rats has significantly increased in the SPS + ARX100 group compared to the SPS group(p<0.05). In OFT, the number of staying in the central space has significantly increased in the SPS + ARX100 group(p<0.01). In FST, immobility has significantly decreased in SPS + ARX50 group and SPS + ARX100 group(p<0.05). The concentration of serotonine, dopamine and BDNF expression has increased significantly in SPS + ARX100 group compared to SPS group(p<0.05) Conclusions : In the SPS-induced PTSD experiment, ARX increased sucrose intake and the numbers of crossing in the central zone space in OFT, decreased immobility time in FST, and increased concentration of serotonin, dopamine, and BDNF. It can be postulated that the ARX could be effective for the treatment of PTSD.

• Advances in robotics research
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• v.2 no.1
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• pp.99-112
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• 2018

The main contribution of this work is the design of a field programmable gate array (FPGA) based ARX-Laguerre proportional-integral observation (PIO) system for fault detection and identification (FDI) in a multi-input, multi-output (MIMO) nonlinear uncertain dynamical robot manipulators. An ARX-Laguerre method was used in this study to dynamic modeling the robot manipulator in the presence of uncertainty and disturbance. To address the challenges of robustness, fault detection, isolation, and estimation the proposed FPGA-based PI observer was applied to the ARX-Laguerre robot model. The effectiveness and accuracy of FPGA based ARX-Laguerre PIO was tested by first three degrees of the freedom PUMA robot manipulator, yielding 6.3%, 10.73%, and 4.23%, average performance improvement for three types of faults (e.g., actuator fault, sensor faults, and composite fault), respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.2 s.54
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• pp.115-121
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• 2009

The paper presents a signal-based damage detection algorithm of ARX model using dynamic acceleration data. An ARX model correlates acceleration data measured at two locations in a structure by considering those two sets of data as input and output signals. For detecting damage, the error between the measured data and the predicted response from the defined ARX model is computed in time and used for a statistical evaluation. A normal distribution function from the error in time is constructed and its statistical characteristic values are used for the evaluation of damage. By comparing the normal distribution functions before and after damage, three different types of damage indices are proposed. The efficiency and limitation of the proposed algorithm with the statistical evaluation of damage indices have been examined and discussed through laboratory experiments.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.160-162
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• 1998

본 논문은 실시간 운영체계인 ARX 의 독특한 메커니즘을 바탕으로 한 POSIX 의 thread library( Pthread library)의 구현에 대하여 다룬다. ARX Pthread library는 POSIX 1003.lc의 규약을 따르며 실시간 프로그램밍의 특성에 맞도록 이를 확장한 주기적인 thread, deadine handler등의 확장된 인터페이스를 제공한다. 이와 더불어 정확한 실시간 특성을 제공하기 위하여 사용자 수준 타이머의 관리도 제공하고 있다. 한편 ARX 의 핵심인 가살쓰레드와 개선된 스케줄링 이벤트 업콜 방식을 바탕으로 사용자 수준 쓰레드와 사용자 수준 스케줄러의 동기화를 제공하는 사용자 수준 동기화 도구를 구현하였다. 이러한 Pthread library를 사용한 응용프로그램의 timing anlysis의 결과는 ARX 의 뛰어난 실시간 처리 능력과 함께 다양한 실시간 응용 프로그램의 요구를 수용할 수 있음을 보여준다.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.10
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• pp.827-832
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• 2002

We propose a prediction method of the pollutant and a synchronous classification of the current state of SOx emission in the power plant. We use the auto-regressive with exogeneous (ARX) model as a predictor of SOx emission and use a radial basis function network (RBFN) as a pattem classifier. The ARX modeling scheme is implemented using recursive least squares (RLS) method to update the model parameters adaptively. The capability of SOx emission monitoring is utilized with the application of the RBFN classifier. Experimental results show that the ARX model can predict the SOx emission concentration well and ARX modeling parameters can be a good feature for the state monitoring. in addition, its validity has been verified through the power spectrum analysis. Consequently, the RBFN classifier in combination with ARX model is shown to be quite adequate for monitoring the state of SOx emission.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.6
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• pp.287-293
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• 2017

Sometimes, it is impossible to install a sensor on a certain location of a structure due to the size of a structure or poor surrounding environments. Even if possible, sensors can be frequently malfunctioned or improperly operated due to lack of adequate maintenance. These kind of problems are solved by the virtual sensing methods in various engineering fields. Virtual sensing technology is a technology that can measure data even though there is no physical sensor. It is expected that this technology can be also applied to the construction field effectively. In this study, a virtual sensing technology based on ARX model is proposed. An ARX model is defined by using the simulated data through a structural analysis rather than by actually measured data. The ARX-based virtual sensing model can be applied to estimate unmeasured response using a transfer function that defines the relationship between two point data. In this study, a simulation and experimental study were carried out to examine the proposed virtual sensing method with a laboratory test on a cable-stayed model bridge. Acceleration measured at a girder is transformed to estimate a cable tension through the ARX model-based virtual sensing.

• Korean Chemical Engineering Research
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• v.45 no.1
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• pp.67-72
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• 2007

An efficient method for identification of MIMO state space model has been developed by combining partial least squares (PLS) regression, balanced realization, and balanced truncation. In the developed method, a MIMO system is decomposed into multiple MISO systems each of which is represented by a high-order ARX model and the parameters of the ARX models are estimated by PLS. Then, MISO state space models for respective MISO ARX transfer function are found through realization and combined to a MIMO state space model. Finally, a minimal balanced MIMO state space model is obtained through balanced realization and truncation. The proposed method was applied to the design of model predictive control for temperature control of a high pressure $CO_2$ solubility measurement system.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.157-159
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• 1998

쓰레드는 프로그램의 동시성을 표현하는데 적합하고, 프로세서 모델에 비하여 동기화나 문맥교환의 비용을 줄일 수 있어 기존의 멀티 프로세스 프로그래밍을 대체하고 있다. 운영체계에서 멀티쓰레팅 환경의 제공은 이제 필수적이며, 좋은 성능을 위해서는 운영체계의 지원이 필요하다. ARX 실시간 운영체계는 유저 레벨 멀티쓰레팅을 지원하고 있으며 쓰레드의 성능을 높이고 유저 레벨에서 실시간 스케쥴링이 가능하도록 하기 위하여 동적 가상 쓰레드 바인딩(dynamic virtual stack binding)과 스케쥴링 이벤트 업콜(scheduling event upcall)등의 기법을 지원한다. 본 논문에서는 자바 가상 머신을 통하여 ARX 운영체계의 쓰레드 라이브러리의 성능을 측정하고 다른 운영체계의 멀티쓰레드 라이브러리와 성능 비교를 하였다. 실험결과 ARX 가 제공하는 쓰레드 라이브러리가 다른 운영체계에 비해 우수한 성능을 보여줌을 확인하였다.

• Earthquakes and Structures
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• v.7 no.6
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• pp.1093-1118
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• 2014

A sophisticated story-wise stiffness identification method for a shear building structure is applied to the case where the shear building is subjected to an actual micro-tremor. While the building responses to earthquake ground motions are necessary in the previous method, it is shown that micro-tremors can be used for identification within the same framework. This enhances the extended usability and practicality of the previously proposed identification method. The difficulty arising in the limit manipulation at zero frequency in the previous method is overcome by introducing an ARX model. The weakness of small SN ratios in the low frequency range is avoided by using the ARX model together with filtering and introducing new constraints on the ARX parameters.