• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.1
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• pp.59-65
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• 2007

HPI (High-speed Portable Internet) system which provides high speed internet services is going to be commercialized soon. Since HPI provides simultaneously four different service types such as UGS (Unsolicited Grant Service), rtPS (real time Polling Service), nrtPS(non-real time Polling Service), and BE (Best Effort) under different QoS (Quality of Service) requirements and limited wireless channel resources, efficient packet scheduling mechanisms are necessary to increase the utilization of channels as well as to satisfy the various QoS requirements. This study regards the traffic data to be served as time series and proposes a new packet scheduling algorithm based on the nonparametric statistical test. The performance of the newly proposed algorithm is evaluated through the simulation analysis using a simulator that can evaluate the performance of packet scheduling mechanisms under various values of system parameters and measures such as packet delay time, data transmission rate, number of loss packets, and channel utilization.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.1005-1009
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• 2005

The On Board Computer System (ORCS) used for rolling stocks is one of the core equipments in trains, which deals with collecting real-time data of a train to display and record the train's statuses, control the train, and support the driver and maintenance function. Resides, due to high reliability and high speed communication required lately for various electronics including signal1ing devices, train protection system, and multimedia, the necessity of a more robust train communication network is on the lise. This study aims at understanding the technological trend of the current train communication network in order to rapidly cope with the tendency above and providing fundamental data for designing a more advanced communication network for high-speed trains hereafter.

• Journal of Ocean Engineering and Technology
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• v.15 no.1
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• pp.1-6
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• 2001

This study focuses on the potential flow analysis for a hull with the transom stern. The method is based on a low order panel method. The Kelvin type free-surface boundary condition which is known to better fit experimental data for a high speed is applied. To treat a dry transom stern effect a special treatment for the free-surface boundary condition is adopted at the free-surface region after the transom stern. Trim and sinkage, which are important in high speed ships, are considered by an iterative method. Pressure and momentum approaches are used to calculate the wave resistance. Numerical calculations are performed for Athena hull and these results are compared with the experimental data and also other computational results.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1142-1144
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• 2003

This Paper presents a speed controller based on the adaptive fuzzy tuning method for brushless DC(BLDC) motor drives under load variations. Generally, the speed tracking control systems use PI controller due to its simple structure and easy of design. PI controller, however, suffers from the electrical machine parameter variations and disturbances. In order to improve the tracking control performance under load variations, PI controller of which the parameters are modified during operation by adaptive fuzzy tuning method. This method based on optimal fuzzy logic system has simple structure and computational simplicity. It needs only sample data which is obtained by optimal controller off-line. As the sample data implemented in the adaptive fuzzy system can be modified or extended, a flexible control system can be obtained. Simulation results show the usefulness of the proposed controller.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.537-540
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• 2008

This paper reviews the operation standards and manuals of earthquake monitoring system for Gyungbu high speed railroad. The domestic earthquake monitoring system detects the acceleration data at the locations of lower part of pier and deck of viaducts and bridges, not like foreign system to do the surface ground accelerations. For the purpose of evaluating the behaviors of the domestic earthquake monitoring system, measured acceleration data on the Odaesan earthquake at Iwon viaduct were analysed. The values of maximum acceleration level of the viaduct were increased from 0.0089g(EW component) of the lower part of pier to 0.014g(EW component) on the deck of the viaduct. And also the predominant periods and frequencies were analysed by the frequency domain analysis.

• Journal of Korean Institute of Industrial Engineers
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• v.26 no.4
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• pp.306-314
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• 2000

In this paper we present a new approach to estimate link travel speed based on the hybrid neuro-fuzzy network. It combines the fuzzy ART algorithm for structure learning and the backpropagation algorithm for parameter adaptation. At first, the fuzzy ART algorithm partitions the input/output space using the training data set in order to construct initial neuro-fuzzy inference network. After the initial network topology is completed, a backpropagation learning scheme is applied to optimize parameters of fuzzy membership functions. An initial neuro-fuzzy network can be applicable to any other link where the probe car data are available. This can be realized by the network adaptation and add/modify module. In the network adaptation module, a CBR(Case-Based Reasoning) approach is used. Various experiments show that proposed methodology has better performance for estimating link travel speed comparing to the existing method.

• International Journal of Safety
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• v.5 no.2
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• pp.1-5
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• 2006

A data acquisition and processing system for measuring the current collection signals of the Korean High-speed Railway is developed. The current collection system is composed of a pantograph and the overhead catenary that supplies electrical power to the train through the pantograph. The system simultaneously measures the signals generated at the interface between the catenary and the pantograph through the accelerometers, load cells and strain gauges placed at various locations. The on-track test data are processed to evaluate the current collection reliability. The fiequency analysis of the signals reveals the presence of several structural vibration modes in the pantograph, as well as the components arising from the periodicity in the structure of the catenary and pantograph at the interface. The feasibility of predicting the contact performance from the measured signals is also demonstrated.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.532-535
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• 2003

In this paper, we propose a new algorithm that can enhance the speed of template matching of hand vascular pattern person verification or recognition system. Various template matching algorithms have advantages in the matching accuracy, but most of the algorithms suffer from computational burden. To reduce the computational amount, with accuracy maintained, we propose following template matching scenario as follows. firstly, original hand vascular image is re-sampled in order to reduce spatial resolution. Secondly, reconstructed image is projected to vertical and horizontal direction, being converted to two one dimensional (1D) data. Thirdly, converted data is used to estimate spatial discrepancy between stored template image and target image. Finally, matching begins from where the estimated order is highest, and finishes when matching decision function is computed to be over certain threshold. We've applied the proposed algorithm to hand vascular pattern identification application for biometrics, and observed dramatic matching speed enhancement. This paper presents detailed explanation of the proposed algorithm and evaluation results.

• Journal of The Korean Society For Urban Railway
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• v.6 no.4
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• pp.309-317
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• 2018

Sudden pressure changes caused by the high-speed train entering the entrance of the tunnel are propagated into the tunnel and spread out around the tunnel in the form of a micro pressure wave at the exit of the tunnel. This phenomenon can cause noise and vibration around the tunnel, causing damage to the surroundings. Analysis of this phenomenon is very difficult, but the development of analytical technology has revealed more phenomena than in the past. In this study, we propose this method of analysis and compare it with the experimental data to show the data with higher reliability.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.396-404
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• 2021

It is important to verify that the contracted speed-power performance of a ship is satisfied in sea trials. International Organization for Standardization (ISO) has published the procedure for measuring and assessing ship speed during sea trials. The results obtained from actual sea conditions inevitably include various uncertainty factors. In this study, double run tests were performed on one container ship to analyze the uncertainty of sea trial on three maximum continuous rating conditions. The uncertainty factors and scale of uncertainty were examined based on the measured raw data during sea trial. The results indicate that the expanded uncertainty for ideal power performance is approximately ±1.4% at 95% confidence level (coverage factor k = 2) and most of the uncertainty factors were because of the shaft power measurement system.