• International Journal of Aeronautical and Space Sciences
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• v.7 no.1
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• pp.129-136
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• 2006

A new guidance synthesis for anti-ship missiles to control impact angle and impact time is proposed in this paper. The flight vehicle is assumed as a 1st order lag system to consider more practical system. The proposed guidance synthesis enhances the survivability of anti-ship missiles because multiple anti-ship missiles with the proposed synthesis can hit the target simultaneously. The control input to satisfy constraints of zero miss distance and impact angle, and the feedforward bias control input to control impact time constitute the guidance law. The former is from trajectory shaping guidance, the latter is from neural network. And particle swarm optimization method is introduced to furnish reference input and output for learning in neural network. The performance of the proposed synthesis in the accuracy of impact time and angle is validated by numerical examples.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.3
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• pp.271-287
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• 2015

In this article, a more generalized form of the impact time and angle control guidance law is proposed based on the linear quadratic optimal control methodology. For the purpose on controlling an additional constraint such as the impact time, we introduce an additional state variable that is defined to be the jerk (acceleration rate). Additionally, in order to provide an additional degree of freedom in choosing the guidance gains, the performance index that minimizes the control energy weighted by an arbitrary order of time-to-go is considered in this work. First, the generalized form of the impact angle control guidance law with an additional term which is used for the impact time control is derived. And then, we also determine the additional term in order to achieve the desired impact time. Through numbers of numerical simulations, we investigate the superiority of the proposed guidance law compared to previous guidance laws. In addition, a salvo attack scenario with multiple missile systems is also demonstrated.

• Journal of Information Technology Services
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• v.6 no.3
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• pp.47-67
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• 2007

While earlier research reports focused on Internet addiction among adolescents, this research examines the direct/indirect impact of socio-psychological variables like stress level, self-consciousness (self-esteem, self-control, and self-efficacy), and Internet use control on Internet addiction among adults. The fact that 62.4% of survey respondents were diagnosed as Internet addicts demonstrates that this concern about Internet addiction among adults is valid. This research, first, shows the direct impact of socio-psychological variables on Internet addiction. Low self-esteem, low self-control, high self-efficacy, high levels of stress, and high Internet-use control lead to a severe level of Internet addiction. Second, self-consciousness variables mediate the impact of stress on the addiction, but the mediating role is not so significant as the direct impact. Internet-use control plays as a partial moderator between self-esteem, self-control and addiction. Internet-use control is a useful measure for Internet addition at work. In addition, businesses may take personality, as well as environmental conditions, and organizational management process into account to minimize the impact of the addiction.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.89-94
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• 1994

This paper presents an impact control algorithm for reducing the potentially damaging effects by interation of redundant manipulators with their environments. In the. proposed control algorithm, the redundancy is resolved at the torque level by locally minimizing joint torque, subject to tire operational space dynamic formulation which maps tire joint torque set into the operational forces. For a given pre-impact velocity of the manipulator, the proposed approach is on generating joint space trajectories throughout the motion near the contact which instantaneously minimize the impulsive force which is a scalar function of manipulator's configurations. This is done by using the null space dynamics which does not affect the motion of an end-effector. The comparative evaluation of the proposed algorithm with a local torque optimization algorithm without reducing impact is performed by computer simulation. The simulation results illustrate the effectiveness of the algorithm in reducing both the effects of impact and large torque requirements.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.91-94
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• 1995

A newly developed discrete-time control design method for impact machines is proposed. It is composed of identification and control using neural networks, where the optimal controller with saturationn and no use of velocity measurements is obtained. By computer simulation, the proposed method is demonstrated to be effective: as the training progresses, the cost function becomes smaller, the proposed control is superior to PID control tuned with Ziegler-Nichols (Z-N) parameters; robust performance with respect to uncertainty, disturbances and working time is so good.

• The Journal of Information Systems
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• v.22 no.4
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• pp.49-69
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• 2013

Recently, enterprises have reinforced security control in order to prevent infringement of personal information and abuse of customer information by insiders. However, the reinforcement of security control by enterprises makes it difficult for internal users to perform business by using a business information system. There is, therefore, a need for research on various fields, which makes it possible to establish an appropriate security control policy while minimizing an impact on business. The present research verifies and analyzes an impact on difficulty in business of internal users using customer information, which is caused by security control performed by display restriction on customer information identifiers. The present research is intended to academically develop a technique for statistically analyzing an impact degree and a causal relationship between security control and an impact on business, which is a dichotomous variable, and to practically contribute to the establishment of an efficient security policy in consideration of an impact on business when an enterprise applies security control. A research target was internal business information systems of domestic securities enterprises, data was collected by questionnaire, and verification/analysis was performed by logistic regression analysis.

• Smart Structures and Systems
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• v.31 no.5
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• pp.455-467
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• 2023

Impact damper is a passive damping system that controls undesirable vibration with mass block impacting with stops fixed to the excited structure, introducing momentum exchange and energy dissipation. However, harmful momentum exchange may occur in the random excitation increasing structural response. Based on the mechanism of impact damping system, a semi-active impact damper (SAID) with controllable impact timing as well as a semi-active control strategy is proposed to enhance the seismic performance of engineering structures in this paper. Comparative experimental studies were conducted to investigate the damping performances of the passive impact damper and SAID. The extreme working conditions for SAID were also discussed and approaches to enhance the damping effect under high-intensity excitations were proposed. A numerical simulation model of SAID attached to a frame structure was established to further explore the damping mechanism. The experimental and numerical results show that the SAID has better control effect than the traditional passive impact damper and can effectively broaden the damping frequency band. The parametric studies illustrate the mass ratio and impact damping ratio of SAID can significantly influence the vibration control effect by affecting the impact force.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.46-56
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• 1999

A semi-actively controlled impact system which adjusts an impulse exerted by the external impact is studies. The main control variables are internal pressure difference inside the cylinder and the shock absorber displacement while it travels. Compared to a conventional one so called a passive system with a variable orifice inside the cylinder, a semi-actively controlled system utilizes an external orifice controlled by a highly fast responding electrical proportional valve. This device overcomes the temperature and viscosity change due to continuous operating and keeps the desired pressure difference and displacement in every operation. In this article a new prototype impact system is designed and manufactured based on a semi-actively control system. Through computer simulations and experiments, we verify the possibility of controlling the shock absorber pressure and displacement. After investigating the control performance a modified semi-actively controlled system with better control performance is also proposed.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2509-2512
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• 2005

In this paper, a position control scheme of the ink droplet is presented for the high image quality and print speed inkjet printer. The proposed scheme estimates the impact position and compensates it by control of the fire strobe time based on the dynamic equations describing the moving trajectory of the ink droplet. Compared to the conventional fire strobe control which is based on the simple synchronization the fire strobe with the position signal of the inkjet nozzle, the proposed control scheme provides more accurate impact position control during the carrier is moving with accelerated or decelerated speed as well as constant speed. The availability of printing during the acceleration and deceleration states of the carrier moving enables the print speed up and the frame size down which means the cost down.

• Smart Structures and Systems
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• v.24 no.1
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• pp.95-110
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• 2019

The semi-active impact damper (SAID) is proposed to improve the damping efficiency of traditional passive impact dampers. In order to investigate its damping mechanism and vibration control effects on realistic engineering structures, a 20-story nonlinear benchmark building is used as the main structure. The studies on system parameters, including the mass ratio, damping ratio, rigid coefficient, and the intensity of excitation are carried out, and their effects both on linear and nonlinear indexes are evaluated. The damping mechanism is herein further investigated and some suggestions for the design in high-rise buildings are also proposed. To validate the superiority of SAID, an optimal passive particle impact damper ($PID_{opt}$) is also investigated as a control group, in which the parameters of the SAID remain the same, and the optimal parameters of the $PID_{opt}$ are designed by differential evolution algorithm based on a reduced-order model. The numerical simulation shows that the SAID has better control effects than that of the optimized passive particle impact damper, not only for linear indexes (e.g., root mean square response), but also for nonlinear indexes (e.g., component energy consumption and hinge joint curvature).