• Journal of Institute of Control, Robotics and Systems
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• v.14 no.7
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• pp.647-655
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• 2008

This paper presents real-time algorithm for an ultrasonic Local Positioning System(LPS). An ultrasonic LPS consists of 4 transmitters and n receivers. Each transmitter transmits an sequential ultrasonic signal to avoid interference of ultrasonic signal. This method is a noneffective application for a fast object. Because receiver detects four sequential transmissive ultrasonic signal and calculates a position. This paper proposes the method which 4 transmitters transmit simultaneous ultrasonic signal and each transmitter distinguished by frequencies and codes. And Auto-Correlation Function(ACF) method separates codes from an ultrasonic echo signal which is interference of each transmitter's code. If the receiver uses only ACF method, it is difficult to implement real time application for increased computation. This paper implements LPS using dual frequencies and ACF method. Using dual frequencies reduces codes length. The reduced codes length save computation in ACF. To prove this algorithm by experiment, high performance DSP(digital signal processor) used. The result shows the performance of the designed system is good enough positioning.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.69-76
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• 2018

This paper studies the Turbo Codes, the concatenation of Turbo Codes and Reed-Solomon (RS) codes on Orthogonal frequency-division multiplexing (OFDM) in digital communication channel, and then analysis the performances of the new concatenated Forward Error Correct (FEC) scheme applied to an OFDM system based on the digital terrestrial video broadcasting (DVB-T) scheme. We compared the results with the standard DVB-T convolutional codes performances on Additive White Gaussian Noise (AWGN) channels. The simulation results shown that by employing turbo codes with only a few numbers of iterations, the performances of the overall system can be improved significantly. These results will be obtained by applying an appropriate interleaver technique in the concatenated FEC procedure.

• International Journal of Control, Automation, and Systems
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• v.6 no.6
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• pp.809-817
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• 2008

Program plagiarism is widespread due to intelligent software and the global Internet environment. Consequently the detection of plagiarized source code and software is becoming important especially in academic field. Though numerous studies have been reported for detecting plagiarized pairs of codes, we cannot find any profound work on understanding the underlying mechanisms of plagiarism. In this paper, we study the evolutionary process of source codes regarding that the plagiarism procedure can be considered as evolutionary steps of source codes. The final goal of our paper is to reconstruct a tree depicting the evolution process in the source code. To this end, we extend the well-known bioinformatics approach, a local alignment approach, to detect a region of similar code with an adaptive scoring matrix. The asymmetric code similarity based on the local alignment can be considered as one of the main contribution of this paper. The phylogenetic tree or evolution tree of source codes can be reconstructed using this asymmetric measure. To show the effectiveness and efficiency of the phylogeny construction algorithm, we conducted experiments with more than 100 real source codes which were obtained from East-Asia ICPC(International Collegiate Programming Contest). Our experiments showed that the proposed algorithm is quite successful in reconstructing the evolutionary direction, which enables us to identify plagiarized codes more accurately and reliably. Also, the phylogeny construction algorithm is successfully implemented on top of the plagiarism detection system of an automatic program evaluation system.

• Journal of the Korea Society of Computer and Information
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• v.24 no.5
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• pp.27-33
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• 2019

One of serious security threats is a botnet-based attack. A botnet in general consists of numerous bots, which are computing devices with networking function, such as personal computers, smartphones, or tiny IoT sensor devices compromised by malicious codes or attackers. Such botnets can launch various serious cyber-attacks like DDoS attacks, propagating mal-wares, and spreading spam e-mails over the network. To establish a botnet, attackers usually inject malicious URLs into web source codes stealthily by using data hiding methods like Javascript obfuscation techniques to avoid being discovered by traditional security systems such as Firewall, IPS(Intrusion Prevention System) or IDS(Intrusion Detection System). Meanwhile, it is non-trivial work in practice for software developers to manually find such malicious URLs which are hidden in numerous web source codes stored in web servers. In this paper, we propose a security defense system to discover such suspicious, malicious URLs hidden in web source codes, and present experiment results that show its discovery performance. In particular, based on our experiment results, our proposed system discovered 100% of URLs hidden by Javascript encoding obfuscation within sample web source files.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.187-190
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• 2001

A new ultrasound imaging technique based on simultaneous multiple transmit focusing using orthogonal modified Golay codes is presented. modified Golay codes are used to increase signal-to-noise-ratio(SNR) and maximize the transmit power efficiency(TPE). Conventional Golay codes consist of a pair of complementary codes with same length and can be compressed into a delta-like signal due to their complementary property. In the present work, two modified Golay codes focused at different depths are transmitted at the same time, which are mutually orthogonal. On receive, these orthogonal modified Golay codes are separately compressed into two short pulses and individually focused. These two focused beam are combined to form a frame of image with improved lateral resolution. Computer simulations are performed to verity the proposed method improves the lateral resolution of image compared with the conventional echo system.

• Journal of Korea Multimedia Society
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• v.24 no.8
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• pp.1012-1019
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• 2021

Currently, since the black-white QR (Quick Response) codes have limited storage capacity, color QR codes have been actively being studied. By multiplexing 3 colors, the color QR codes can allow the code capacity to be increased by three times, however, the color multiplexing brings about the possibility of crosstalk and noises in the acquisition process of the final image, incurring the decrease of bit-recognition rate. In order to improve the bit recognition rate, while keeping the storage capacity high, this paper proposes a new type of color QR code which uses the pattern information as well as the color information, and then analyzes how to increase the bit recognition rate. For this aim, the paper presents an efficient system which extracts embedded information from color QR code and then, through practical experiments, it is shown that the proposed color QR codes improves the bit recognition rate and are useful for commercial applications, compared to the conventional color codes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.479-482
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• 2022

Recently, various artificial intelligence technologies are being applied to smart factory, finance, healthcare, and so on. When handling data requiring protection of privacy, distributed learning techniques are used. For distribution of information with privacy protection, encoding private information is required. Minimal codes has been used in such a secret-sharing scheme. In this paper, we explain the relationship between the characteristics of the minimal codes for application in distributed systems. We briefly deals with previously known construction methods, and presents extension methods for minimal codes. The new codes provide flexibility in distribution of private information. Furthermore, we discuss application scenarios for the extended codes.

• The Journal of Korean Obstetrics and Gynecology
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• v.32 no.1
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• pp.73-84
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• 2019

Objectives: The purpose of this study is to collect and analyze the KCD codes applied to the treatment of 27 postpartum women who had been treated with Korean traditional medicine in a Korean medicine hospital, so that this study may be used as a basic data for setting the direction of postpartum Korean medical treatment research. Methods: It was approved by the Institutional Review Board (IRB) of ${\bigcirc}{\bigcirc}$ University medical center (IRB approval number : WSOH IRB H1708-02-01). Twenty-seven postpartum women who had been treated at ${\bigcirc}{\bigcirc}$ University medical center were received outpatient treatment for two weeks (from September 27, 2017 to January 5, 2018), and the KCD codes applied to the mothers were collected after obtaining the consent. On the day of registration of the study, the fertility, obstetric history and high-risk pregnancies were identified through an interview. Results: 1. The mean age of the 27 subjects was $33.33{\pm}3.99\;years$ old. Among the subjects, 17 mothers (63.0%) were high-risk pregnancy and 10 mothers (37.0%) were normal. 2. Among the 22 major disease categories, 8 categories were used. M code (musculoskeletal system) was used 243 times (70.85%), followed by R code (unclassified symptom) of 51 times (14.87%) and U code (special purpose code) of 23 times (6.71%). 3. The most commonly used code among the ten frequently used codes was M25.57 (joint pain, ankle and foot), a total of 47 times. Of the remaining nine codes, except for R60.1 (systemic edema) and U68.4 (The deficiency of yang in Bi), all codes were M codes (musculoskeletal system). 4. The M code (musculoskeletal system) was the most used major disease category in high-risk group, a total of 159 times. But in specific categories, the most commonly used code was R60.1 (systemic edema), a total of 28 times. 5. In normal group, the M code (musculoskeletal system) was the most used major disease category, a total of 84 times. Also, in specific categories, the most commonly used code was M25.57 (joint pain, ankle and foot), total 29 times. 6. The U code, corresponding to 'the diagnosis of childbirth and other obstetrical medical use', was used 23 times (6.71%), O code three times (0.87%) and Z code two times (0.58%), which was less than 10% of the total number of codes used. Conclusion: When analyzing KCD codes related to Korean medicine treatment for postpartum diseases, it is important to select the KCD codes that reflect the actual clinical state.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1982.10a
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• pp.47-50
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• 1982

A baseband data transimission system is implemented on a microcomputer for performance study on some NRS line codes. These codes are compared in terms of eye width, BER, and power spectrum.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6C
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• pp.337-342
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• 2011

In 2009, polar codes, proposed by Arikan, are theoretically proven codes to achieve capacity with acceptable encoding and decoding complexity. Currently, polar codes using channel polarization phenomenon are studied in security and data compression fields etc. In this paper, we consider the practical communication system and propose the construction method of polar codes with finite length and fixed code rate. Also, we show the outstanding performance and corresponding construction method of polar codes found by heuristic simulation.