• International Journal of Computer Science & Network Security
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• 제23권9호
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• pp.8-16
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• 2023

In Japan, high-speed ground transportation service using linear motors at speeds of 500 km/h is scheduled to begin in 2027. To accommodate 5G services in trains, a subcarrier spacing frequency of 30 kHz will be used instead of the typical 15 kHz subcarrier spacing to mitigate Doppler effects in such high-speed transport. Furthermore, to increase the cell size of the 5G mobile system, multiple base station antennas will transmit identical downlink (DL) signals to form an expanded cell size along the train rails. In this situation, the forward and backward antenna signals are Doppler-shifted in opposite directions, respectively, so the receiver in the train may suffer from estimating the exact Channel Transfer Function (CTF) for demodulation. In a previously published paper, we proposed a channel estimator based on Delay and Doppler Profiler (DDP) in a 5G SISO (Single Input Single Output) environment and successfully implemented it in a signal processing simulation system. In this paper, we extend it to 2×2 MIMO (Multiple Input Multiple Output) with spatial multiplexing environment and confirm that the delay and DDP based channel estimator is also effective in 2×2 MIMO environment. Its simulation performance is compared with that of a conventional time-domain linear interpolation estimator. The simulation results show that in a 2×2 MIMO environment, the conventional channel estimator can barely achieve QPSK modulation at speeds below 100 km/h and has poor CNR performance versus SISO. The performance degradation of CNR against DDP SISO is only 6dB to 7dB. And even under severe channel conditions such as 500km/h and 8-path inverse Doppler shift environment, the error rate can be reduced by combining the error with LDPC to reduce the error rate and improve the performance in 2×2 MIMO. QPSK modulation scheme in 2×2 MIMO can be used under severe channel conditions such as 500 km/h and 8-path inverse Doppler shift environment.

• 융합보안논문지
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• 제23권1호
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• pp.139-145
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• 2023

한국 육군은 기동화, 지능화, 초연결형 Army TIGER 체계 등 최첨단 미래형 강군 육성을 추진하고 있다. 미래 보병여단은 다영역작전에서 전투수행이 가능하도록 분대 단위 전술차량으로 기동성을 증대시키고, 지상무인로봇, 감시정찰드론 등 다양한 무기체계를 전력화할 예정이다. 또한 무기체계를 통해 수집한 데이터를 초연결 네트워크로 실시간 송·수신하고 학습시키는 지능형 부대를 육성할 것이다. 이러한 군의 발전 계획을 통해 미래의 보병여단은 더 많은 데이터를 유통시킬 것이다. 그러나 현재 육군의 전술정보통신체계는 미래 무기체계의 대용량 정보를 유통하기에 상대적으로 낮은 전송속도와 대역폭, 수동적 네트워크 관리, 기동 간 통신 지원 제한 등 미래의 부대의 전술통신체계로 운용하기에는 한계가 있다. 따라서 본 논문에서는 한국 육군의 미래 보병여단의 무기체계를 분석하고, 보병여단의 기동 상황을 묘사하기 위한 공격작전 시나리오를 바탕으로 지상·공중·위성 계층의 통합 전술통신망 M&S를 통해 미래 보병여단이 갖추어야 할 정보유통능력을 제시한다.

• 융합보안논문지
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• 제22권5호
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• pp.145-154
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• 2022

최근 봇넷의 광범위한 확산과 고도의 정교함은 기업과 사용자뿐만 아니라 국가 간 사이버전에도 심각한 결과를 초래하고 있다. 이 때문에 봇넷을 탐지하고자 하는 연구는 꾸준히 되고 있다. 하지만, DGA 기반의 봇넷은 기존의 시그니처 및 통계 기반의 기술로는 탐지율은 높지만, 오탐율 또한 높은 한계가 있다. 이에 본 논문에서는 DGA 기반의 봇넷을 탐지하고자 문자 기반의 n-gram을 활용한 탐지모델을 제안한다. 제안한 모델을 통해 기존의 탐지 기술의 한계인 탐지율을 높이고 오탐율을 최소화할 수 있다. 다양한 DGA 봇넷에서 사용하는 대규모의 도메인 데이터셋과 정상 도메인에 대한 실험을 통해 기존의 모델보다 성능이 우수함을 확인하였다. 제안된 모델의 오탐율은 2~4% 미만이며 전체 탐지 정확도와 F1 점수는 모두 97.5%임을 확인하였다. 이처럼 본 논문에서 제안한 모델을 통해 DGA 기반의 봇넷에 대한 탐지 및 대응 능력이 향상될 것을 기대한다.

• International Journal of Computer Science & Network Security
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• 제23권7호
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• pp.1-8
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• 2023

An Orthogonal Frequency Division Multiplexing (OFDM) based wireless communication system has drawn wide attention for its high transmission rate and high spectrum efficiency in not only radio but also Underwater Acoustic (UWA) applications. Because of the narrow sub-carrier spacing of OFDM, orthogonality between sub-carriers is easily affected by Doppler effect caused by the movement of transmitter or receiver. Previously, Doppler compensation signal processing algorithm for Desired propagation path was proposed. However, other Doppler shifts caused by delayed Undesired signal arriving from different directions cannot be perfectly compensated. Then Receiver Bit Error Rate (BER) is degraded by Inter-Carrier-Interference (ICI) caused in the case of Multi-path Doppler channel. To mitigate the ICI effect, a modified Delay and Doppler Profiler (mDDP), which estimates not only attenuation, relative delay and Doppler shift but also sampling clock shift of each multi-path component, is proposed. Based on the outputs of mDDP, an ICI canceling multi-tap equalizer is also proposed. Computer simulated performances of one-tap equalizer with the conventional Time domain linear interpolated Channel Transfer Function (CTF) estimator, multi-tap equalizer based on mDDP are compared. According to the simulation results, BER improvement has been observed. Especially, in the condition of 16QAM modulation, transmitting vessel speed of 6m/s, two-path multipath channel with direct path and ocean surface reflection path; more than one order of magnitude BER reduction has been observed at CNR=30dB.

• International Journal of Computer Science & Network Security
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• 제23권10호
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• pp.135-146
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• 2023

An effective educational program warrants the inclusion of an innovative construction which enhances the higher education efficacy in such a way that accelerates the achievement of desired results and reduces the risk of failures. Educational Decision Support System (EDSS) has currently been a hot topic in educational systems, facilitating the pupil result monitoring and evaluation to be performed during their development. Insufficient information systems encounter trouble and hurdles in making the sufficient advantage from EDSS owing to the deficit of accuracy, incorrect analysis study of the characteristic, and inadequate database. DMTs (Data Mining Techniques) provide helpful tools in finding the models or forms of data and are extremely useful in the decision-making process. Several researchers have participated in the research involving distributed data mining with multi-agent technology. The rapid growth of network technology and IT use has led to the widespread use of distributed databases. This article explains the available data mining technology and the distributed data mining system framework. Distributed Data Mining approach is utilized for this work so that a classifier capable of predicting the success of students in the economic domain can be constructed. This research also discusses the Intelligent Knowledge Base Distributed Data Mining framework to assess the performance of the students through a mid-term exam and final-term exam employing Multi-agent system-based educational mining techniques. Using single and ensemble-based classifiers, this study intends to investigate the factors that influence student performance in higher education and construct a classification model that can predict academic achievement. We also discussed the importance of multi-agent systems and comparative machine learning approaches in EDSS development.

• International Journal of Computer Science & Network Security
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• 제24권6호
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• pp.161-170
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• 2024

With the technological advances, the humans have made so much progress in the ease of living and now incorporating the use of sight, motion, sound, speech etc. for various application and software controls. In this paper, we have explored the project in which gestures plays a very significant role in the project. The topic of gesture control which has been researched a lot and is just getting evolved every day. We see the usage of computer vision in this project. The main objective that we achieved in this project is controlling the computer settings with hand gestures using computer vision. In this project we are creating a module which acts a volume controlling program in which we use hand gestures to control the computer system volume. We have included the use of OpenCV. This module is used in the implementation of hand gestures in computer controls. The module in execution uses the web camera of the computer to record the images or videos and then processes them to find the needed information and then based on the input, performs the action on the volume settings if that computer. The program has the functionality of increasing and decreasing the volume of the computer. The setup needed for the program execution is a web camera to record the input images and videos which will be given by the user. The program will perform gesture recognition with the help of OpenCV and python and its libraries and them it will recognize or identify the specified human gestures and use them to perform or carry out the changes in the device setting. The objective is to adjust the volume of a computer device without the need for physical interaction using a mouse or keyboard. OpenCV, a widely utilized tool for image processing and computer vision applications in this domain, enjoys extensive popularity. The OpenCV community consists of over 47,000 individuals, and as of a survey conducted in 2020, the estimated number of downloads exceeds 18 million.

• 한국컴퓨터정보학회논문지
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• 제28권12호
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• pp.129-136
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• 2023

정부는 공공데이터 품질관리 수준평가를 진행하여 공공 개방데이터의 품질관리를 진행하고 있다. 공공 개방데이터는 XML, JSON, CSV 등 여러 오픈포맷 형태로 제공되며 CSV 형식이 대다수를 차지한다. 이러한 CSV 형식의 공공 개방데이터 품질진단 시 품질진단 담당자가 공공 개방데이터 파일의 필드명과 필드 내 데이터에 의존하여 필드 별 도메인을 판단하여 진단한다. 그러나 대량의 개방 데이터 파일을 대상으로 품질진단을 수행하기 때문에 많은 시간이 소요된다. 또한 의미 파악이 어려운 필드의 경우 품질진단의 정확성이 품질진단 담당자의 데이터 이해도 역량의 영향을 받는다. 본 논문은 필드명과 데이터 분포 통계를 이용한 CSV 형식 공공 개방데이터의 도메인 판별 모델을 제안하여 품질진단 결과가 품질진단 담당자의 역량에 좌지우지 되지 않도록 일관성과 정확성을 보장하고 진단 소요 시간 단축을 지원한다. 본 논문의 모델 적용 결과 행정안전부에서 제공하는 파일형식 개방데이터 진단도구보다 2.8% 높은 약 77%의 정답률을 보였다. 이를 통해 공공데이터 품질관리 수준진단·평가에 제안 모델 적용 시 정확성을 향상시킬 수 있을 것으로 기대한다.

• 한국통신학회논문지
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• 제29권8C호
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• pp.1076-1085
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• 2004

최근 프라이버시 적용이 IT분야의 가장 중요한 문제의 하나로 대두되고 있다. 프라이버시 보호는 조직의 데이터 처리 시스템에 프라이버시 정책을 적용함으로써 달성 될 수 있다. 전통적인 보안 모델은 다소간 프라이버시 바인딩과 같은 기본적인 프라이버시 요구를 적용하기에 부적절하다. 본 논문은 조직에 프라이버시 정책을 적용할 수 있는 하나의 확장된 역할기반 접근제어 모델을 제안한다. 이 모델은 RBAC과 도메인-타입 적용, 그리고 프라이버시 정책을 결합함으로써 프라이버시 보호와 함께 문맥기반 접근제어를 제공한다. 프라이버시 정책은 역할에 프라이버시 등급을, 데이터에 고객의 프라이버시 선호에 따른 데이터 프라이버시 등급을 부여하는 데이터 사용 정책을 적용함으로써 달성한다. 또 이 모델을 응용에 적용하기 위하여 작은 병원 모델이 사용되었다.

• ETRI Journal
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• 제42권4호
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• pp.619-632
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• 2020

Highly dispersive S-boxes are desirable in cryptosystems as nonlinear confusion sublayers for resisting modern attacks. For a near optimal cryptosystem resistant to modern cryptanalysis, a highly nonlinear and low differential probability (DP) value is required. We propose a method based on a piecewise linear chaotic map (PWLCM) with optimization conditions. Thus, the linear propagation of information in a cryptosystem appearing as a high DP during differential cryptanalysis of an S-box is minimized. While mapping from the chaotic trajectory to integer domain, a randomness test is performed that justifies the nonlinear behavior of the highly dispersive and nonlinear chaotic S-box. The proposed scheme is vetted using well-established cryptographic performance criteria. The proposed S-box meets the cryptographic performance criteria and further minimizes the differential propagation justified by the low DP value. The suitability of the proposed S-box is also tested using an image encryption algorithm. Results show that the proposed S-box as a confusion component entails a high level of security and improves resistance against all known attacks.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.876-879
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• 2004

The buried fiber optic cable as a distributed intrusion sensor for detecting and locating intruders along the long perimeters is proposed. Phase changes resulting from either the pressure of the intruder on the ground immediately above the buried fiber or from seismic disturbances in the vicinity are sensed by a phase-sensitive optical time-domain reflectometer. Light pulses from a Er:fiber cw laser with a narrow, <3kHz-range, spectral width and a frequency drift of < 1 MHz/min are injected into one end of the fiber, and the backscattered light from the fiber is monitored with a photodetector. Results of preliminary studies, measurement of phase changes produced by pressure and seismic disturbances in buried fiber optic cables and simulation of ${\varphi}-OTDR$ response over long fiber paths, to establish the feasibility of the concept are described. The field experiments indicate adequate phase changes, more than 1t-rad, are produced by intruders on foot and vehicle for burial depths in the 0.2 m to 1 m range in sand, clay and fine gravel soils. The simulations predict a range of 10 km with 35 m range resolution and 30 km with 90 m range resolution. This technology could in a cost-effective manner provide enhanced perimeter security.