• Structural Engineering and Mechanics
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• v.42 no.3
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• pp.425-448
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• 2012

In this paper, a new damage detection and quantification method has been presented to perform detection and quantification of structural damage under ambient vibration loadings. To extract modal properties of the structural system under ambient excitation, natural excitation technique (NExT) and eigensystem realization algorithm (ERA) are employed. Sensitivity matrices of the dynamic residual force vector have been derived and used in the parameter subset selection method to identify multiple damaged locations. In the sequel, the steady state genetic algorithm (SSGA) is used to determine quantified levels of the identified damage by minimizing errors in the modal flexibility matrix. In this study, performance of the proposed damage detection and quantification methodology is evaluated using a finite element model of a truss structure with considerations of possible experimental errors and noises. A series of numerical examples with five different damage scenarios including a challengingly small damage level demonstrates that the proposed methodology can efficaciously detect and quantify damage under noisy ambient vibrations.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.63-67
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• 2004

The problem is improving the positioning precision of a permanent magnet linear synchronous motor (PMLSM). Thus, this paper presents the design and realization of an adaptive dither to reduce the force ripple in PMLSM. A composite control structure is used, consisting of three components: a simple feed-forward component, a PID feedback component and an adaptive feed-forward compensator (AFC). Especially adaptive feed-forward component cancel out detent force using wavelet transformation. Computer simulation results verify the effectiveness of the proposed scheme for high precision motion trajectory tracking using the PMLSM

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.115-121
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• 2001

In micro automation technology, the concurrent realization of a high resolution and a large operating rage has been achieved by a dual actuator, usually called by piggy-back system, conventionally. But, because of its manufacturing cost, the complexity of control, and the limit of overall bandwidth, the contract-free and single servo actuators have been suggested with specific applications. In this paper, we suggest a novel non-contact surface actuator suing combination of the Lorentz force and the magnetized force, and discuss the actuating principles including an analytical approach. Differently from the existing planar system, an operating range of the suggested system can be expanded by an additional attachment of active elements. Therefore, it is estimated to be suitable for the next-generation moving system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.2
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• pp.281-292
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• 2017

It is demanded to promote research and development of cyber weapons system and core technology in response to the ongoing cyber attack of North Korea. In this paper, core technologies of the future cyber weapon system are developed and the factors affecting the realization timing of core technologies were analyzed. 9 core technology groups and 36 core technologies are derived. Afterwards, these core technology groups are compared to the operation phase of the joint cyber warfare guideline and the cyber kill chain of Lockheed Martin. As a result of the comparison, it is confirmed that the core technology groups cover all phases of the aforementioned tactics. The results of regression analyses performed on the degree of influence by each factor regarding the moment of core technology realization show that the moment of core technology realization approaches more quickly as factors such as technology level of the most advanced country, technology level of South Korea, technology transfer possibility from the military sector to the non-military sector(spin-off factor), and technology transfer possibility from the non-military sector to the military sector(spin-on factor) increase. On the contrary, the moment of core technology realization is delayed as the degree at which the advanced countries keep their core technologies from transferring decrease. The results also confirm that the moment of core technology realization is not significantly correlated to the economic ripple effect factor. This study is meaningful in that it extract core technologies of cyber weapon system in accordance with revision of force development directive and join cyber warfare guideline, which incorporated cyber weapon system into formal weapon system. Furthermore, the study is significant because it indicates the influential factor of the moment of core technology realization.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.894-897
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• 2004

In this paper, we address a position control scheme for a stage system, which is levitated and driven by electric magnetic actuators. This consists of a levitating object (called platen) with 4 permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion by the vertical and horizontal forces. Dynamic equations of the stage system are derived based on Newton-Euler method and its special Jacobian matrix describing a relation between the Joint velocity and platen velocity is done. There are proposed two control schemes for positioning, which are Cartesian space controller and Joint space controller. The control performance of the Cartesian space controller is better than the Joint space controller in task space trajectory while the Joint space controller is simpler than the Cartesian space controller in controller realization.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.2
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• pp.16-21
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• 2006

In this study, the analytic realization of chatter mechanism using radial basis neural network(RBNN) was introduced and compared with the conventional stability analysis. In this regard, the FFT and time series spectrum analysis was used as a criterion for the existence of chatter in end-milling force. The desired coded outputs of chatter was trained and finally converged to desired outputs. The output of the RBNN match well with the conventional desired stability lobe. Using this trained data, the stability boundary of the radial basis neural network was acquired using the contour plotting. As a result, the proposed stability lobe boundary using RBNN consists well with the conventional analytical boundary that is calculated in characteristic equation of transfer function in chatter dynamics. In this RBNN analysis, two input and three output parameters were used in this paper.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.78-80
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• 2005

Haptic interface apparatus is the device which can offer users virtual reality not only by visualization of virtual space but also by force or tactile feedback. In this paper, we designed and fabricated a 2D haptic interface device that can be used for various purposes, and implemented a virtual air-hockey system that users can easily find in game rooms. By suitable modeling and haptic rendering, users can feel the impact and the reaction force with his/her hand holding the handle through 2D haptic interface device when he/she hit an air-hockey puck with the handle. Through the trial demonstration. we observed the reasonable effect of direction and speed of a ball like doing in reality.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.31.3-31
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• 2001

In this paper, an automatic pipe-cutting machine that uses magnet to attach itself to pipe and performs unmanned cutting process is proposed. The machine uses magnetic force to prevent slip and to attach the machine to the pipe against gravity. The magnetic force is adjustable by changing the gap between the magnet and the pipe. During pipe cutting process, the gravity acting on the pipe-cutting machine widely varies nonlinearly where the gravity is function of climbing angle of the cutting machine along the pipe. The cutting quality is deteriorated with irregular cutting speed. It is necessary to maintain constant cutting speed to obtain good cutting quality ...

• Journal of Power Electronics
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• v.6 no.1
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• pp.8-17
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• 2006

In this paper, we propose a fault-tolerant control system for the position control and vibration suppression of a flexible arm robot. The proposed control system has a strain gauge sensor signal observer based on a reaction force observer and detects a fault by monitoring an estimated error. In order to improve the estimation accuracy, the plant parameters included in the sensor signal observer are updated by using the strain gauge sensor signal in normal time through the adaptive law. After fault detection, the proposed control system exchanges the faulty sensor signal for the estimated one and switches to a fault mode controller so as to maintain the stability and the control performance. We confirmed the effectiveness of the proposed control system through several experiments.

• International Journal of Computer Science & Network Security
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• v.22 no.8
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• pp.1-6
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• 2022

In this paper, we will present the realization of a facial recognition system using the ESP32-CAM board controlled by an Arduino board. The goal is to monitor a remote location in real time via a camera that is integrated into the ESP32 IOT board. The acquired images will be recorded on a memory card and at the same time transmitted to a pc (a web server). The development of this remote monitoring system is to create an alternative between security, reception, and transmission of information to act accordingly. The simulation results of our proposed application of the facial recognition domain are very efficient and satisfying in real time.