• Publications of The Korean Astronomical Society
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• v.23 no.2
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• pp.91-107
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• 2008

In this paper, we introduce the performance evaluation and development of Raw VLBI Data Buffer(RVDB) system for the synchronized playback processing of observed data in Korea-Japan Joint VLBI Correlator(KJJVC). The high-speed correlation processing system is under development so that the radio data obtained with 8192 channels and 8 Gbps speed from 16 stations will be able to be processed. When the recorded data of each station are played to correlator, the time synchronization of each station is very important because the correlator should process the data obtained with same time and condition. There are many types of recorder systems in the East Asia VLBI Network (EAVN). Therefore it is required to prepare the special time synchronized playback processing system to synchronize the time tag of observed data. The developed RVDB system consists of Data Input Output(DIO), 10GbE switch, and Disk Data Buffer(DDB). It can record the data with maximum 2 Gbps speed, and can play back the data to correlator with nominal 2 Gbps speed. To enable to play back the data of different playback system to the correlator, we developed the high-speed time synchronized playback processing system. We carried out the experiments of playing back and correlation for gigabit correlator and VCS trial product so as to confirm the performance of developed time synchronized playback processing system. In case of online and offline playing back experiment for gigabit correlator, we confirmed that the online and offline correlation results were the same. In case of playing back experiment for VCS trial product, we verified that the wide band and narrow band correlation results were also the same. Through the playing back experiments of RVDB system, the effectiveness of developed RVDB system was verified. In this paper, the system design, construction and experimental results are shown briefly.

• Korean Journal of Cognitive Science
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• v.33 no.3
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• pp.155-168
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• 2022

In this paper, we introduce the SNUDM-G, a diffusion model analysis tool with improved computational speed. Although the diffusion model has been applied to explain various cognitive tasks, its use was limited due to computational difficulties. In particular, SNUDM(Koh et al., 2020), one of the diffusion model analysis tools, has a disadvantage in terms of processing speed because it sequentially generates 20,000 data when approximating the diffusion process. To overcome this limitation, we propose to use graphic processing units(GPU) in the process of approximating the diffusion process with a random walk process. Since 20,000 data can be generated in parallel using the graphic processing units, the estimation speed can be increased compared to generating data through sequential processing. As a result of analyzing the data of Experiment 1 by Ratcliff et al. (2004) and recovering the parameters with SNUDM-G using GPU and SNUDM using CPU, SNUDM-G estimated slightly higher values for certain parameters than SNUDM. However, in term of computational speed, SNUDM-G estimated the parameters much faster than SNUDM. This result shows that a more efficient diffusion model analysis for various cognitive tasks is possible using this tool and further suggests that the processing speed of various cognitive models can be improved by using graphic processing units in the future.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.4
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• pp.153-161
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• 2018

This paper describes the performance improvement of Software (SW) digital filter using GPU (Graphical Processing Unit). The previous developed SW digital filter has a problem that it operates on a CPU (Central Processing Unit) basis and has a slow speed. The GPU was introduced to filter the data of the EAVN (East Asian VLBI Network) observation to improve the operation speed and to process data with other stations through filtering, respectively. In order to enhance the computational speed of the SW digital filter, NVIDIA Titan V GPU board with built-in Tensor Core is used. The processing speed of about 0.78 (1Gbps, 16MHz BW, 16-IF) and 1.1 (2Gbps, 32MHz BW, 16-IF) times for the observing time was achieved by filtering the 95 second observation data of 2 Gbps (512 MHz BW, 1-IF), respectively. In addition, 2Gbps data is digitally filtered for the 1 and 2Gbps simultaneously observed with KVN (Korean VLBI Network), and compared with the 1Gbps, we obtained similar values such as cross power spectrum, phase, and SNR (Signal to Noise Ratio). As a result, the effectiveness of developed SW digital filter using GPU in this research was confirmed for utilizing the data processing and analysis. In the future, it is expected that the observation data will be able to be filtered in real time when the distributed processing optimization of source code for using multiple GPU boards.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.4
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• pp.191-199
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• 2014

Currently, HTTP traffic has been developed rapidly due to appearance of various applications and services based web. Accordingly, HTTP Traffic classification is necessary to effective network management. Among the various signature-based method, Payload signature-based classification method is effective to analyze various aspects of HTTP traffic. However, the payload signature-based method has a significant drawback in high-speed network environment due to the slow processing speed than other classification methods such as header, statistic signature-based. Therefore, we proposed various classification method of HTTP Traffic based HTTP signatures of hierarchical structure and to improve pattern matching speed reflect the hierarchical structure features. The proposed method achieved more performance than aho-corasick to applying real campus network traffic.

• Journal of IKEEE
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• v.24 no.3
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• pp.791-796
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• 2020

In this paper, "Q-Bone", a 3^rd generation blockchain platform with enhanced security and flexibility, was developed. As a 3^rd generation blockchain platform, it exploits BP (block producer) to increase processing speed. It has many advantages as follows. It improves both security and speed by mixing RSA (Rivest-Shamir-Adleman) and AES (advanced encryption standard). It improves flexibility by exploiting gateway to convert between apps and blockchain with different programming language. It increases processing speed by combining whole transactions into one block and distribute it when too many transactions occur. It improves search speed by inserting sequence hash into transaction data. It was implemented and applied to pet communication service and academy-instructor-student matching service, and it was verified to work correctly and effectively. Its processing speed is 3,357 transactions/second, which shows excellent performance.

• Journal of the Korea Society of Computer and Information
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• v.12 no.1 s.45
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• pp.155-160
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• 2007

Because output of multi-code CDMA system adapted high speed data transmission becoming multi-level system use linear amplifier in output stage and complex output signal. Therefore, Multi-Code CDMA system has shortcoming of high price, high complexity etc.. Binary CDMA technology that allow fetters in existing CDMA technology to supplement this shortcoming proposed. In binary CDMA system When correlator process high speed data, bottle-neck phenomenon is happened on synchronization acquisition process, it is very important parameter. Because existent correlator must there be advantage that power consumption is small but flow addition of several stages to receive correlation's value, the processing speed has disadvantage because the operation amount is much. Therefore in this paper, proposed correlator has characteristic such as data is able to high speed processing, chip area is independent and power consumption is constant in structure in binary CDMA system.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.3
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• pp.177-182
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• 2008

Because output of multi-code CDMA system adapted high speed data transmission becoming multi-level system use linear amplifier in output stage and complex output signal. Therefore, Multi-Code CDMA system has shortcoming of high price, high complexity etc. Binary CDMA technology that allow fetters in existing CDMA technology to supplement this shortcoming proposed. In binary CDMA system When correlator process high speed data, bottle-neck phenomenon is happened on synchronization acquisition process, it is very important parameter. Because existent correlator must there be advantage that power consumption is small but flow addition of several stages to receive correlation's value, the processing speed has disadvantage because the operation amount is much. Therefore in this paper, proposed correlator has characteristic such as data is able to high speed processing, chip area is independent and power consumption is constant in structure in binary CDMA system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1449-1457
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• 2007

A panorama image is constructed by merging several overlapped images to a big one. There are two kinds of methods, feature based and direct method, in the construction. Feature based one has a merit of processing speed faster than direct one. But, it is difficult to be implemented under slower processing environments such as mobile device. This paper proposed high speed construction method of a panorama image. The algorithm extremely improved matching speed by reducing the number of matching parameters using scene shot guider, and additionally adapted local matching technique to reduce matching error caused by the fewer matching parameters. In the experiments, it was shown that the proposed method required about 0.078 second in processing time, about 17 times shorter than the feature based one, for 24-bit color images of $320{\times}240$ size.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.10
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• pp.690-696
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• 2004

This paper is proposed a hybrid intelligent controller based on the vector controlled surface permanent magnet synchronous motor(SPMSM) drive system. The hybrid combination of neural network and fuzzy control will produce a powerful representation flexibility and numerical processing capability. Also, this paper is proposed speed control of SPMSM using neural network-fuzzy(NNF) control and speed estimation using artificial neural network(ANN) Controller. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. The error between the desired state variable and the actual one is back-propagated to adjust the rotor speed, so that the actual state variable will coincide with the desired one. The back propagation mechanism is easy to derive and the estimated speed tracks precisely the actual motor speed. This paper is proposed the theoretical analysis as well as the simulation results to verify the effectiveness of the new method.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.221-226
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• 1999

It can be acquired the high effective productivity through of high speed, precision of machine tools, and then, machine tools will be got a competitive power. Industrially advanced countries already developed that the high speed feed is 50m/min using the high speed ball screw. Also, a lot of problems have happened the feed and servo drive system. It is necessary to study about the character of positioning accuracy, heat generation and high speed/accuracy control for feed/servo drive system of high speed/accuracy. In this study, we make use of high performance vertical machine center with a ball screw of large-scale-lead. Also, we'll apply the high-speed/accuracy control technology in this part of feedforward control, multi-buffering block size, etc. Using the design of the mechanical element and high-speed precision control, the basic design concept can be established.