• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.3131-3149
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• 2016

In-band Full-duplex (IBFD) wireless communication allows improved throughput for wireless networks. The current Half-duplex (HD) medium access mechanism Request to Send/Clear to Send (RTS/CTS) has been directly applied to IBFD wireless networks. However, this is only able to support a symmetric dual link, and does not provide the full advantages of IBFD. To increase network throughput in a superior way to the HD mechanism, a novel three-way handshaking access mechanism RTS/SRTS (Second Request to Send)/CTS is proposed for point to multipoint (PMP) IBFD wireless networks, which can support both symmetric dual link and asymmetric dual link communication. In this approach, IBFD wireless communication only requires one channel access for two-way simultaneous packet transmissions. We first describe the RTS/SRTS/CTS mechanism and the symmetric/asymmetric dual link transmission procedure and then provide a theoretical analysis of network throughput and delay using a Markov model. Using simulations, we demonstrate that the RTS/SRTS/CTS access mechanism shows improved performance relative to that of the RTS/CTS HD access mechanism.

• 한국국방경영분석학회지
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• 제24권1호
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• pp.110-131
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• 1998

A stochastic modeling of combat that takes more realistic situations into account has been studied with deep concern. Either the firing strategies or network formations are very important elements in the analysis of combat. The first objective of this study is to evaluate how the different strategies affect the outcomes of combat. An analytical approach has been used in an attempt to understand a small-sized battle. The results are validated and compared with existing simulation models. Extending to the moderate size of battle may be achieved with ease. Secondly, an attempt has been made to study and investigate a way to solve combat in a different fashion. We divided a two-on-two battle into two separate one-on-one battles and connected them into a network. New elements considered such as delay time of starting a firefight on a particular node or search time for the next target when a kill occurs are defined and used as the input parameters. The discussions are made to validate the hypothesized model and ask if the results are meaningful and useful in the analysis of combat operations or not.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2004년도 가을 학술발표논문집 Vol.31 No.2 (1)
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• pp.286-288
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• 2004

무선 통신의 발달로 언제 어디서나 누구와도 통신이 자유롭게 되었다 하지만, 무선 통신을 사용하게 됨으로써 통신 사용자와 액세스 포인트, 액세스 포인트와 서버(Server)가 통신을 할 경우 유선 네트워크와는 다른 인증 방식이 요구되었다. 무선 네트워크에서 사용자 인증을 위해 801.x EAP, SSID, CHAP 및 WEP를 이용한 다양한 인증 방식이 사용되고 있다. 본 논문에서는 사용자를 안전하게 인증할 수 있는 효율적인 인증 방법을 제안한다. 절기서는 기존의 PPP CHAP을 수정하여 인증 서버와 사용자간의 상호 인증을 할 수 있도록 했다. 또한 강한 일-방향 해시 함수(Strength One-Way Hash Function)을 사용하여 생성된 결과 값을 일회용 패스워드(One Time Password:OTP)로 사용하여 재공격(Reply Attack)을 방지했다.

• International Journal of Computer Science & Network Security
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• 제22권1호
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• pp.276-282
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• 2022

One of the most essential foundations upon which big institutions rely in delivering cloud computing and hosting services, as well as other kinds of multiple digital services, is the security of infrastructures for digital and information services throughout the world. Distributed denial-of-service (DDoS) assaults are one of the most common types of threats to networks and data centers. Denial of service attacks of all types operates on the premise of flooding the target with a massive volume of requests and data until it reaches a size bigger than the target's energy, at which point it collapses or goes out of service. where it takes advantage of a flaw in the Transport Control Protocol's transmitting and receiving (3-way Handshake) (TCP). The current study's major focus is on an architecture that stops DDoS attacks assaults by producing code for DDoS attacks using a cloud controller and calculating Round-Tripe Time (RTT).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 D
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• pp.2580-2582
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• 2004

In this paper, a Neural Network(NN) based approach for classification of two dimensions images. The proposed algorithm is able to apply in the actual industry. The described diagnostic algorithm is presented to defect surface failures on tiles. A way to get data for a digital image process is several kinds of it. The tiles are scanned and the digital images are preprocessed and classified using neural networks. It is important to reduce the amount of input data with problem specific preprocessing. The auto-associative neural network is used for feature generation and selection while the probabilistic neural network is used for classification. The proposed algorithm is evaluated experimentally using one hundred of the real tile images. Sample image data to preprocess have histogram. The histogram is used as input value of probabilistic neural network. Auto-associative neural network compress input data and compressed data is classified using probabilistic neural network. Classified sample images are determined by human state. So it is intervened human subjectivity. But digital image processing and neural network are better than human classification ability. Therefore it is very useful of quality control improvement.

• ETRI Journal
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• 제38권6호
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• pp.1145-1152
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• 2016

Because the nodes in a wireless sensor network (WSN) are mobile and the network is highly dynamic, monitoring every node at all times is impractical. As a result, an intruder can attack the network easily, thus impairing the system. Hence, detecting anomalies in the network is very essential for handling efficient and safe communication. To overcome these issues, in this paper, we propose a rule-based anomaly detection technique using roaming honeypots. Initially, the honeypots are deployed in such a way that all nodes in the network are covered by at least one honeypot. Honeypots check every new connection by letting the centralized administrator collect the information regarding the new connection by slowing down the communication with the new node. Certain predefined rules are applied on the new node to make a decision regarding the anomality of the node. When the timer value of each honeypot expires, other sensor nodes are appointed as honeypots. Owing to this honeypot rotation, the intruder will not be able to track a honeypot to impair the network. Simulation results show that this technique can efficiently handle the anomaly detection in a WSN.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2022년도 춘계학술대회
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• pp.275-276
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• 2022

해상교통관제사는 항로폭이 협소한 항만에서 선박 충돌사고 예방을 위해 one-way로 항해하도록 선박의 입·출항 대기 지시를 한다. 현재 해상교통관제사의 입·출항대기 지시는 과학적이고 통계적인 데이터를 기반으로 하지 않고 해상교통관제사의 개인 역량에 따라 편차가 크다. 이에 따라 본 연구에서는 항만에서의 선박 입·출항 대기 지시를 위한 정확한 이동 시간을 예측하기 위해 선박 및 기상 데이터를 수집하여 1d-합성곱신경망 모델을 구축하였다. 제안한 모델이 다른 앙상블 기계학습 모델보다 4.5% 이상 개선된 것을 확인하였다. 본 연구를 통해 다양한 상황에서도 선박 입·출항 소요시간 예측이 가능하여 해상교통관제사는 선박에게 정확한 정보 제공 및 대기지시 판단에 도움이 될 것으로 기대된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권11호
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• pp.4087-4102
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• 2014

Two-way relaying is an effective way of improving system spectral efficiency by making use of physical layer network coding. However, energy efficiency in OFDM-based bidirectional relaying with asymmetric traffic requirement has not been investigated. In this study, we focused on subcarrier transmission mode selection, bit loading, and power allocation in a multicarrier single amplified-and-forward relay system. In this scheme, each subcarrier can operate in two transmission modes: one-way relaying and two-way relaying. The problem is formulated as a mixed integer programming problem. We adopt a structural approximation optimization method that first decouples the original problem into two suboptimal problems with fixed subcarrier subsets and then finds the optimal subcarrier assignment subsets. Although the suboptimal problems are nonconvex, the results obtained for a single-tone system are used to transform them to convex problems. To find the optimal subcarrier assignment subsets, an iterative algorithm based on subcarrier ranking and matching is developed. Simulation results show that the proposed method can improve system performance compared with conventional methods. Some interesting insights are also obtained via simulation.

• 한국산학기술학회논문지
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• 제19권4호
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• pp.664-673
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• 2018

산업제어시스템(ICS, Industrial Control System)은 과거에는 폐쇄 네트워크로 운영되었으나 최근에는 정보통신 서비스와 연결되어 운영되면서 사이버 공격으로 인한 피해로 이어지고 있다. 이에 대한 대책으로 정보통신기반보호법이 제정되고 보안가이드라인이 배포되고 있지만 제어망에서 업무망으로의 일방향 정책만 있어 다양한 실제 제어 환경에 대한 보안가이드가 필요하며 국제 표준으로 IEC 62443의 경우 산업제어시스템 참조 모델을 정의하고 침입 차단 시스템을 이용한 영역 보안 모델을 제시하고 있으나 폐쇄 네트워크로 운영되는 산업제어망을 침입 차단 시스템만으로 외부 네트워크와과 연계하기에는 부담이 있다. 본 논문에서는 국내외 산업제어시스템 보안 모델 및 연구 동향을 분석하고 다양한 국내 산업제어망의 실제 연동 환경에 적용할 수 있는 산업제어시스템 보안 모델을 제안한다. 또한 현재 상용 경계 보안 제품들인 침입 차단 시스템, 산업용 침입 차단 시스템, 망 연계 장비, 일방향 전송 시스템 등의 보안성을 분석하였다. 이를 통하여 국내 구축 사례와 정책에 대한 비교를 통해 보안성이 향상되는 것을 확인하였다. 4차 산업혁명 시대를 맞이하여 스마트 팩토리, 스마트 자동차, 스마트 플랜트 등 다양한 산업제어 분야에 대한 보안 관리 방안에 적용할 수 있을 것이다.

• 한국환경복원기술학회지
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• 제1권1호
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• pp.70-83
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• 1998

With the launch of a new millenium of the 21st century ahead, one of tasks that need to be considered in urban ecological aspect is the understanding of impact of continuing urbanization on urban ecosystem, habitats, and various species of animals and plants. In addition, alternatives and measures to mitigate these impacts including environment restoration should be pursued. In this article, the following points will be reviewed; 1) the definition and significance of an eco-city and "ecological network", 2) the necessity of an eco-network as one of factors composing an eco-city, in the aspects of urban planning and urban ecology, 3) ways to build an urban ecological network and example of foreign countries, 4) as an example of a city in Korea, the present state and impending tasks of the ecological network of Seoul city, and 5) a brief conclusion and suggestion. By providing a basic tool called "an ecological network" for urban space planning, it attempts to contribute in promoting networking of cities (netropolis) and urban biodiversity. It is believed that how to create an ecological network in an artificially developed urban area is a pending issue we are faced with. Herein lies the necessity of natural environment restoration and creation based on the so-called the Third Ecology. Regarding the efforts to return the Nature to urban citizens, there is a need to view the development of a desirable urban ecological network as the starting point and finishing point of the effort. In this way, it is believed that the objectives of urban sustainability through netropolis development would also be achieved.