• Journal of the Korean Society of Industry Convergence
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• v.24 no.4_2
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• pp.501-507
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• 2021

In this study, In order to prevent the safety accidents caused by the sliding, to develop the non-slip grating, the stability judgment based on the span length of the grating and the gap of the bearing bar is performed. The structural analysis of Grating was carried out in accordance with the provisions set out in Grating's load-bearing test conditions. As the span length increases, the deflection increases and the stress and span length tend to be proportional to each other. It was shown that the larger the span, the linear increase in stress and exponential increase in deformation of grating. The maximum stress of grating was approximately 58.2 MPa, indicating a very stable safety rate of about 4.3 compared to the yield strength of the grating material. Based on these results, it will be able to be utilized as the basic data for determining the optimal dimensions of non-slip grading by performing optimal designs in the future.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.6
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• pp.607-613
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• 2019

In this study, we investigate the effect of SNCM616 alloy steel, which is commonly used in industry, such as rotors and crank-shafts, on the surface roughness of CNC HBM with Ø25 mm, 8-blade reamer to objective is to analyze and present optimal cutting conditions. The higher the feedrate for the spindle speed, the rougher the surface roughness. The surface roughness was found to be better when the feed rate was lower. The resultant value of the most accurate surface roughness is Ra 0.756 ㎛, and the optimal cutting conditions are 25 rpm at spindle speed and 20 mm/min at transfer speed.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.5
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• pp.470-477
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• 1990

Singh's multi-level method is extended to the optimal tracking control of a large interconnected dynamical system which has coupled states and coupled inputs. The steady-state tracking error and a convergence condition for the extended multi-level method are derived analytically and the results show that the steady-state tracking error and a convergence rate have to be compromised. Also, a new multi-level method which is advantageous over the Singh's method in steady-state tracking error and computational burden is proposed by introducing nominal inputs into the performance index. The resulting feedback gain matrix and the compensation vector are optimal for all initial conditions so that eventual on-line computation is minimal.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.3
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• pp.151-169
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• 2014

We propose a new technique for autonomous navigation and travelling of mobile robot based on ultrasonic sensors through the narrow labyrinth that leave only distance of a few centimeters on each side between the guides and the robot. In our current implementation the ultrasonic sensor system fires at a rate of 100 ms, that is, each of the 8 sensors fires once during each 100 ms interval. This is a very good firing rate, implemented here for optimal performance. This paper presents an extensively tested and verified solution to the problem of obstacle avoidance. Our solution is based on the optimal placement of ultrasonic sensors at strategic locations around the robot. Both the sensor location and the associated navigation algorithm are defined in such a way that only the accurate radial sonar data is used for accurate travelling.

• Journal of Computing Science and Engineering
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• v.5 no.4
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• pp.316-323
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• 2011

Recently, Proxy Mobile IPv6 (PMIPv6) has received much attention as a mobility management protocol in next-generation all-IP mobile networks. While the current research related to PMIPv6 mainly focuses on providing efficient handovers for unicast-based applications, there has been relatively little interest in supporting multicast services with PMIPv6. To provide support for multicast services with PMIPv6, there are two alternative approaches called Mobile Access Gateway (MAG)-based subscription and Local Mobility Anchor (LMA)-based subscription. However, MAG-based subscription causes a large overhead for multicast joining and LMA-based subscription provides non-optimal multicast routing paths. The two approaches may also cause a high packet loss rate. In this paper, we propose an efficient PMIPv6-based multicast protocol that aims to provide an optimal delivery path for multicast data and to reduce handover delay and packet loss rate. Through simulation studies, we found that the proposed protocol outperforms existing multicast solutions for PMIPv6 in terms of end-to-end delay, service disruption period, and the number of lost packets during handovers.

• Journal of Digital Convergence
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• v.11 no.6
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• pp.199-204
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• 2013

Speech recognition system is shall be composed model of learning from the inaccurate input speech. Similar phoneme models to recognize, because it leads to the recognition rate decreases. Therefore, in this paper, we propose a method of speech recognition optimal learning model configuration using the Bhattacharyya algorithm. Based on feature of the phonemes, HMM feature extraction method was used for the phonemes in the training data. Similar learning model was recognized as a model of exact learning using the Bhattacharyya algorithm. Optimal learning model configuration using the Bhattacharyya algorithm. Recognition performance was evaluated. In this paper, the result of applying the proposed system showed a recognition rate of 98.7% in the speech recognition.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_2
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• pp.1111-1117
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• 2022

Recently, interest in the circular economy has emerged in the industry. As a result, interest in Re-manufacturing, which makes old equipment similar to new products, is growing. In the machine tool industry with many aging equipment, the Re-manufacturing industry is essential, and among them, research on the performance improvement of gear type oil pumps was conducted. The purpose was to achieve the target performance of flow rate and volume efficiency by changing the shape of the gear pump housing clearance and inlet/outlet, and Computational Fluid Analysis and Central Composite Design were conducted using ANSYS CFX 2022 R2 and MINITAB®. The level of each determined factor was determined. 20 design points were derived, and the Flow Rate at each design point was calculated, and the Theoretical Flow Rate was calculated to obtain Volumetric Efficiency. The optimal design point was obtained when the Flow Rate was 140 lpm and the Volumetric Efficiency was maximum, the optimal design point was obtained when both were maximum, and the Surface Plot for each factor was obtained to identify the tendency.

• Journal of information and communication convergence engineering
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• v.5 no.4
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• pp.377-381
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• 2007

Nonlinear effects and chromatic dispersion are the main causes of pulse degradation in high bit-rate WDM transmission systems and several architectures have been proposed to compensate them by means of optical phase conjugation. In this paper, a new method to exploit an optical phase conjugator (OPC) for nonlinearity and dispersion cancellation is disclosed. The proposed method is using optimal total dispersion of each fiber sections and it is simpler than those previously described in literature. Power penalty between WDM channels and the maximum launch power in $28{\times}40$ Gbps WDM transmission system designed by optimal total dispersion are more decreased and more increased than those in the conventional WDM transmission system with OPC, respectively. Furthermore, optimal total dispersion proposed in this research should provide the flexible design of WDM system, which less depends on OPC position.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.246-248
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• 2004

In this paper, we propose an optimal power control algorithm for CDMA cellular systems. The proposed power control algorithm is based on linear quadratic control theory. As the cellular system includes the changeability of system environment or various noise, Kalman filter is adapted to estimate the time-varying interference. This is the well-known linear quadratic Gaussian (LQG) theory. Through this algorithm, power transmission of each mobile with optimal one is more realistic. Simulation results show a fast convergence rate to optimal power value, and a rapid decreasing outage probability.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.179-190
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• 2010

This paper describes a new stochastic heuristic algorithm in engineering problem optimization especially in power system applications. An improved particle swarm optimization (PSO) called adaptive particle swarm optimization (APSO), mixed with simulated annealing (SA), is introduced and referred to as APSO-SA. This algorithm uses a novel PSO algorithm (APSO) to increase the convergence rate and incorporate the ability of SA to avoid being trapped in a local optimum. The APSO-SA algorithm efficiency is verified using some benchmark functions. This paper presents the application of APSO-SA to find the optimal location, type and size of flexible AC transmission system devices. Two types of FACTS devices, the thyristor controlled series capacitor (TCSC) and the static VAR compensator (SVC), are considered. The main objectives of the presented method are increasing the voltage stability index and over load factor, decreasing the cost of investment and total real power losses in the power system. In this regard, two cases are considered: single-type devices (same type of FACTS devices) and multi-type devices (combination of TCSC, SVC). Using the proposed method, the locations, type and sizes of FACTS devices are obtained to reach the optimal objective function. The APSO-SA is used to solve the above non.linear programming optimization problem for better accuracy and fast convergence and its results are compared with results of conventional PSO. The presented method expands the search space, improves performance and accelerates to the speed convergence, in comparison with the conventional PSO algorithm. The optimization results are compared with the standard PSO method. This comparison confirms the efficiency and validity of the proposed method. The proposed approach is examined and tested on IEEE 14 bus systems by MATLAB software. Numerical results demonstrate that the APSO-SA is fast and has a much lower computational cost.