• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3C
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• pp.264-270
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• 2003

Application of the Filtered-X LMS adaptive filter to active noise control requires to estimate the transfer characteristics between the output and the error signal of the adaptive canceler. In this paper, we derive an adaptive control algorithm and analyze its convergence behavior when the acoustic noise is assumed to consist of multiple sinusoids. The results of the convergence analysis of the Filtered-X LMS algorithm indicate that the effects of parameter estimation inaccuracy on the convergence behavior of the algorithm are characterize by two distinct components : Phase estimation error and estimated magnitude. In particular, the convergence of the Filtered-X LMS algorithm is shown to be strongly affected by the accuracy of the phase response estimate. Simulation results of the algorithm are presented which support the theoretical convergence analysis.

• Applied Science and Convergence Technology
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• v.26 no.5
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• pp.114-117
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• 2017

Plasma characteristics of two-dimensional inductively coupled discharge simulation is investigated. Impedance of an inductively coupled plasma discharge was considered. Voltage drops across antenna coils and current variation between coils made different profiles of plasma characteristics. Importance of the capacitive field effect in some case was analyzed.

• Journal of Korea Multimedia Society
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• v.23 no.7
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• pp.830-839
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• 2020

As a popular mathematical framework for modeling decision making, Markov decision process (MDP) has been widely used to solve problem in many engineering fields. MDP consists of a set of discrete states, a finite set of actions, and rewards received after reaching a new state by taking action from the previous state. The objective of MDP is to find an optimal policy, that is, to find the best action to be taken in each state to maximize the expected discounted reward of policy (EDR). In practice, MDP is typically unknown, so simulation-based policy improvement (SBPI), which improves a given base policy sequentially by selecting the best action in each state depending on rewards observed via simulation, can be a practical way to find the optimal policy. However, the efficiency of SBPI is still a concern since many simulation samples are required to precisely estimate EDR for each action in each state. In this paper, we propose a method to select the best action accurately in each state using a small number of simulation samples, thereby improving the efficiency of SBPI. The proposed method accumulates the simulation samples observed in the previous states, so it is possible to precisely estimate EDR even with a small number of samples in the current state. The results of comparative experiments on the existing method demonstrate that the proposed method can improve the efficiency of SBPI.

• Journal of Convergence for Information Technology
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• v.11 no.12
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• pp.244-253
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• 2021

This study examined how the fire evacuation induction service system using a smartphone navigation application in the event of a fire affects the fire evacuation time, and the following conclusions were drawn. 1. The evacuation time was reduced by 22 seconds when the navigation application was used in computer scenario simulation. Even in the demonstration simulation, the evacuation time was reduced by 40 seconds when the navigation application was used. This indicates that the navigation application is effective in shortening the evacuation time in case of fire. 2. As a result of the demonstration scenario simulation, the time until the end of evacuation was 39 seconds faster in the case of evacuation guidance than in the case where it was not conducted. 3. No bottlenecks occurred in the evacuation route during the demonstration scenario simulation. As a result, there was a difference in the time required to complete the evacuation between the computer scenario simulation and the demonstration scenario simulation.

• Journal of the Korea Convergence Society
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• v.11 no.11
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• pp.41-46
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• 2020

The start of the Fourth Industrial Revolution has brought about various changes in the domestic industry in general, and smart factories have spread to companies in the fields of production, manufacturing and logistics, and they are using automation equipment. Especially in the field of logistics automation, AGVs are widely used, and most of them use the line guidance system, which is the traditional AGV drive system. In addition, the demand for AGV system developers, system operators and managers, and maintenance personnel is increasing, and the installation of systems for education is expensive and requires a large space to utilize. It is a situation where systematic education is difficult. In this paper, we propose a virtual simulation-based AGV distance education model for smooth practice of trainees. The proposed model consisted of a model that can drive the AGV by analyzing video information, instead of the line guidance method that is the conventional technology. As a result of self-diagnosis evaluation, it was confirmed that the experimental group through online education had an average satisfaction level of 0.65 higher than the control group using existing equipment, and that it could be used in an online education environment.

• Informatization Policy
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• v.22 no.2
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• pp.19-34
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• 2015

Due to rapid convergence trends in the digital pay TV market, differentiation among the competing medias decreases and substitutability is increasing. The current study aims to explain the effect of service substitutability among competing media on the size of domestic digital pay TV subscribers. For the analysis, the Lotka-Volterra model, an ecological competitive diffusion model, was used to obtain the basic model for a simulation study. A simulation was performed by adjusting independent variables of substitutability to estimate the size of subscriber for particular media. The relationship between the digital cable TV and the IPTV is identified as a predator-prey relationship and the digital cable TV is found to be superior to the IPTV. The simulation results showed that the increase of convergence and substitutability result in the decrease of the entire media market. Especially, the IPTV is estimated to face the greatest loss in this context.

• Journal of the Korea Convergence Society
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• v.11 no.9
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• pp.15-20
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• 2020

Software-related training can be considered essential in situations where software is an important factor in national innovation, growth and value creation. As one of the implementation methods for engineering education, various education through virtual simulations that can educate difficult situations in a similar environment are being conducted. Recently, the construction of smart factories at production and manufacturing sites is spreading, and product inspections using vision systems are being conducted. However, it has many difficulties due to lack of operation technology of vision system, but it requires a lot of cost to construct the system for education of vision system. In this paper, provide an educational virtual simulation model that integrates computer and physics engine camera functions and can extract and transmit video. It is possible to generate an image of 30Hz or more at an average of 35.4FPS of the experimental results of the proposed model, and it is possible to send and receive images in a time of 22.7ms, which can be utilized in an educational virtual simulation educational environment.

• ETRI Journal
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• v.37 no.1
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• pp.175-185
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• 2015

This paper presents a system-of-systems (SoS) approach to the formal modeling of a cyber-physical system (CPS) for simulation-based analysis. The approach is based on a convergence technology for modeling and simulation of a highly complex system in which SoS modeling methodology, hybrid systems modeling theory, and simulation interoperation technology are merged. The methodology maps each constituent system of a CPS to a disparate model of either continuous or discrete types. The theory employs two formalisms for modeling of the two model types with formal specification of interfaces between them. Finally, the technology adapts a simulation bus called DEVS BUS whose protocol synchronizes time and exchange messages between subsystems simulation. Benefits of the approach include reusability of simulation models and environments, and simulation-based analysis of subsystems of a CPS in an inter-relational manner.

• Journal of Digital Convergence
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• v.4 no.1
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• pp.17-30
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• 2006

Recently, Modeling and Simulation, which have been received attention in various in dustries such as national defence, eduction and entertainment, have been researched, and related applications have been developed actively. Especially, it is focused on the to chnology of a virtual reality and a virtual simulation which represents the implementation technology for the simulation education related to the e-Learning industry. However, a solution is needed to fulfill the lack of technology and research about standardize d data elements which could be applied to virtual simulation technologies in common. Therefore, this article suggests the virtual simulation data elements to increase the educational effect of a virtual simulation and interoperability of data among LMS through reference to korean and international standards and the result of related area analysis. In other words, this article aims to define the expression of data element and to propose the guideline elements in the virtual simulation scope.

• Journal of Institute of Convergence Technology
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• v.2 no.2
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• pp.35-39
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• 2012

This paper presents the effect of data-hold methods on stability of haptic system with a virtual wall. When a human operator interacts with virtual wall, the lager the stiffness of the virtual wall is, the more realistic the operator feels that the virtual wall is. However, if the stiffness of the virtual wall becomes extremely large, the system may be unstable. When a virtual wall is designed, it is necessary to analyze the maximum available stiffness to guarantee a stable haptic interaction. The simulation model in this paper is developed based on the haptic device model, sampler, a virtual wall model, and data hold methods to compute the maximum stiffness for stability. The effectiveness of the simulation is evaluated through comparing the results of previous studies with the results of this simulation. In addition, the effects of two data hold methods, that is, zero-order hold (ZOH) and first-order hold (FOH) on the stability are analyzed and the values of the maximum available stiffness are compared through the simulation.