• 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.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.1
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• pp.1-9
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• 2022

Global Navigation Satellite System (GNSS) provides location information using signals from multiple satellites. However, a spoofing attack that forges signals or retransmits delayed signals may cause errors in the location information. To prevent such attacks, authentication protocols considering the navigation message structure of each GNSS can be used. In this paper, we analyze the authentication protocols of Global Positioning System (GPS), Galileo, and BeiDou, and compare the performance of Navigation Message Authentication (NMA) of the above systems, using several performance indicators. According to our analysis, authentication protocols are similar in terms of performing NMA and using Elliptic Curve Digital Signature Algorithm (ECDSA). On the other hand, they are different in several ways, for example, whether to perform Spreading Code Authentication (SCA), whether to use digital certificates and whether to use Timed Efficient Stream Loss-tolerant Authentication (TESLA). According to our quantitative analysis, the authentication protocol of Galileo has the shortest time between authentications and time to first authenticated fix. We also show that the larger the sum of the navigation message bits and authentication bits, the more severely affected are the time between authentications and the time to first authenticated fix.

• Journal of Broadcast Engineering
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• v.19 no.4
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• pp.491-501
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• 2014

Recently, the need for disaster-preventing broadcast has increased gradually to cope with natural disaster like earthquake and tsunami causing enormous losses of both life and property. In disaster-preventing broadcast system, the wake-up signal is used to alert user terminal and switch the current state of channel to the emergency channel, which is for the fast and efficient delivery of emergency information. In this paper, we propose the detection method of wake-up signal for disaster-preventing broadcast systems. The wake-up signals for disaster-preventing broadcast should have a good auto-correlation property in low power and narrow-band conditions that does not affect the existing digital television (DTV) system. The suitability of the m-sequence and complementary code (CC) is analyzed for wake-up signals according to signal to noise ratio. A wake-up signal is proposed by combining the direct sequence spread spectrum (DSSS) technique and pseudo noise (PN) sequences such as Barker and Walsh-Hadamard codes. By using the proposed method, a higher detecting performance can be achieved by the spreading gain compared to the single long m-sequence and the Golay code.

• Journal of Internet Computing and Services
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• v.21 no.1
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• pp.45-55
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• 2020

Due to the development of information and communication technology, the number of new / variant malicious codes is increasing rapidly every year, and various types of malicious codes are spreading due to the development of Internet of things and cloud computing technology. In this paper, we propose a malware analysis method based on string information that can be used regardless of operating system environment and represents library call information related to malicious behavior. Attackers can easily create malware using existing code or by using automated authoring tools, and the generated malware operates in a similar way to existing malware. Since most of the strings that can be extracted from malicious code are composed of information closely related to malicious behavior, it is processed by weighting data features using text mining based method to extract them as effective features for malware analysis. Based on the processed data, a model is constructed using various machine learning algorithms to perform experiments on detection of malicious status and classification of malicious groups. Data has been compared and verified against all files used on Windows and Linux operating systems. The accuracy of malicious detection is about 93.5%, the accuracy of group classification is about 90%. The proposed technique has a wide range of applications because it is relatively simple, fast, and operating system independent as a single model because it is not necessary to build a model for each group when classifying malicious groups. In addition, since the string information is extracted through static analysis, it can be processed faster than the analysis method that directly executes the code.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.168-175
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• 2019

The purpose of this paper is to examine the characteristics of organic relations according to the characteristics of space and place in which human activities are spreading. The diffusion of various human experiences and the interaction of space and place that form a mutual construction network create momentum for expanding individual or collective experiences. The space and place that lead to the interactions of human activities are expressed in various ways. Through the domestic travel program especially, the ways of expressing space and place are spreading as various "fields of experience." The composition and the expression system of a travel program is transformed into a subject of thought, not a mere experience of space and place through the formation of a "field of experience" that can be thought out and thought of as an existing travel style. Therefore, in this study, we examine the characteristics of the MBC Plus channel from a socio-cultural perspective, expressed through the experience of space and place characteristics expressed through a travel program. The result of an analysis of story development composition for this study shows that the experience of space and place minimizes the boundaries of various cultural discounts according to their relationships to food and communication. In addition, the analysis results of a three-way communication structure show that the emotional code of the audience is maximized through the process of maximizing the effect of reality, and minimizing the gap between the cultural differences and the boundaries through the empathic situation and the empathic subject.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.3
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• pp.1-9
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• 2003

We analyze the performances of MC-CDMA and MC-DS/CDMA systems on quasi-synchronized mobile satellite return link. Quasi-synchronization is considered that chip offset between user terminals is within a few chips. Since the transmitted signals of MC-CDMA and MC-DS/CDMA systems have non-constant envelop, they are easily distorted by nonlinearity of transmit amplifier. Since the nonlinear amplifier input signal level of MC-CDMA system using Walsh code to employ frequency domain spreading is lower than that of MC-DS/CDMA system, performance of single user in MC-CDMA system is respectively 2.3dB and 1dB better than that of MC-DS/CDMA system when amplifier input backoff is 0dB and 6dB. However, since interference of MC-DS/CDMA is less than that of MC-CDMA with many subcarriers in quasi-synchronization and AWGN channel, MC-DS/CDMA system is much better than MC-CDMA system as the number of users increases.

• The Journal of Korean Medicine
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• v.31 no.4
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• pp.49-62
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• 2010

Objectives: Current information & communication technology is advancing very rapidly and the ripple effects are spreading all over society traditional Korean medicine (TKM) is no exception. We draw up afuture plan and target system's architecture of KIOM's OASIS to follow the information change and reinforce the supporting infra for TKM research. Methods: First, we analyzed the information circumstances of western and eastern medicine, both overseas and domestic, especially investigating the detailed changes domestically. Second, we grasped the present conditions of OASIS and compared it with other information portals. Finally, we drew a future plan and system architecture from the analysis results. Results: First, the information status of western medicine is much more advanced than TKM's, and overseas information circumstances are likewise more developed than domestics. Second, we found that OASIS is performing the central research infra role well in TKM. Finally we designed an information system architecture which is composed of an infra layer, an application layer and a service layer. Conclusion: We must integrate information materials such as literature, research manpower, facilities and standards to make TKM's knowledge portal successful. In detail, we have to make TKM's information classification code, build up the electronic TKM library and offer complementary and alternative medicine (CAM) trends.

• Journal of IKEEE
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• v.8 no.1 s.14
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• pp.145-151
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• 2004

For wide-band spread spectrum communication systems such as IMT-2000, a digital matched filter is a key device for rapid spreading code synchronization. Although a digital matched filter can be implemented easily, large power consumption at the higher chip rate and large summation delay of longer chip length are the bottleneck of practical use. In this paper, we propose a optimized partial correlation digital matched filter structure which can be constructed of the so-called generalized hierarchical Golay sequence. a partial correlation structure can reduce the number of correlators, but enlarge the size of flip-flops. In this paper, The proposed approach focuses on efficient circuit size, power dissipation, maintaining the operating throughput. A proposed digital matched filter reduce the size of flip-flops by rounding method. and it reduces about 45 percentages of power dissipation and chip area as compared with digital matched filter which is not rounded. rounding. The proposed architecture was verified by using Xilinx FPGA.

• Journal of forensic and investigative science
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• v.1 no.1
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• pp.54-71
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• 2006

The definition of Crime Indictable Upon Complaint (CIC) is crimes which can be prosecuted only with complaints from the victim or his/her direct parents. Sex crimes are the representative examples, rapes and indecent assaults. According to the research referenced in this paper, 74% of sex crimes which had been penalized based on Republic of Korea (ROK) Criminal Code amounts rape and indecent assault are CIC. However, only 20% of perpetrators were confined, and the rest received non-confinement or non-prosecution determination. The review of criminal history checks reveals that 67% of the perpetrators had criminal histories and 39% of them had more than three documented offenses. The CIC was established in order to protect the victim's rights and dignity, respecting the victim's opinion regarding the incident. All kinds of sex crimes then should have been the CIC, but those crimes such as Injury Resulting from Rape, Special Rape, Rape by Special Modus Operandi, Sexual Assault among Relatives and Domestic Violence which have to guarantee the opinion of the victims are prescribed as non-CIC. We therefore conclude that the CIC should be abolished. The abolition of CIC will play an important role in crime prevention because severe penalties for sex crimes will be imposed on the perpetrators. In addition, it will help the sex crime victims retrieve their dignity by spreading recognition widely through the community that sexual assault is not only a social assault but an infringement against human rights.

• 전자공학회논문지 IE
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• v.43 no.2
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• pp.70-74
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• 2006

The performance of conventional direct sequence code division multiple access (DS-CDMA) systems is decreased under environments such as additive white Gaussian noise (AWGN), channel distortion and interference noise due to multiple access user. By means of this parameter, auto correlation value of pseudo noise spreading sequence is decreased at receiver. This techniques which are based on correlation of between signature waveform signal. In this paper, to improve correlation property, we proposed the binary chirp DS-CDMA techniques which combine the DS-CDMA and chirp modulation. The proposed system which is based on binary chirp symbol has a good correlation value. Thus, we called BC DS-CDMA. To evaluate the system's performance, we compare the performance of the proposed systems with DS-CDMA systems under AWGN channel and halogen noise which exists on the powerline. The simulation results show that the proposed method has better performance than conventional technique.