• Journal of information and communication convergence engineering
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• 제15권1호
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• pp.28-36
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• 2017

The medium access control (MAC) protocol based on dynamic time division multiple access/time division duplex (TDMA/TDD) is responsible for random access control and radio resource allocation in dynamic traffic environments. These functions of random access and resource allocation are very important to prevent wastage of resources and improve MAC performance according to various network conditions. In this paper, we propose new random access and resource allocation schemes to guarantee quality of service (QoS) and provide priority services in a dynamic TDMA/TDD system. First, for the QoS guarantee, we propose an adaptive random access and resource allocation scheme by introducing an access probability. Second, for providing priority service, we propose a priority-based random access and resource allocation scheme by extending the first adaptive scheme in both a centralized and a distributed manner. The analysis and simulation results show that the proposed MAC protocol outperforms the legacy MAC protocol using a simple binary exponential backoff algorithm, and provides good differential performance according to priorities with respect to the throughput and delay.

• 융합보안논문지
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• 제11권4호
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• pp.43-49
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• 2011

웹 기반 의료정보는 많은 편리성을 제공하지만 공개된 네트워크 환경에서 나타나는 보안 취약성을 해결하지 않은 채 정보노출의 위험속에 사용이 확대되고 있다. 웹 기반 의료정보 접근시 보안문제에 대한 안전한 방법론 강구없이 기술만 발전시키려한다면 또 다른 위협의 요소를 증가시키는 것이다. 따라서 웹에 기반한 정보활용 보안대책 으로서 웹 기반 의료정보 접근제어 보안 메커니즘 기반 설계가 필요하다. 본 논문은 소프트웨어 아키텍쳐 설계사상을 기반으로 하여 의료정보시스템 접근제어 보안 메커니즘 기반을 설계 하였다. 그 방법론은 새로운 설계절차를 도출하고 아키텍쳐를 설계하며 기능 메커니즘 알고리즘을 구성하는 것 이다. 이를위해서는 웹 기반 다중 환자 정보 접근제어를 위한 보안 아케텍쳐 인프라스트럭가 필요하다. 제안하는 소프트웨어아케텍쳐는 소프트웨어 프레임워크를 도출하고 기능 메커니즘을 구성하는 기반에 관한 구조도를 도출했다. 제안된 시스템를 활용하여 의료정보 어플리케이션을 설계할때 의료정보 사용자는 실시간으로 데이터를 검색하면서도 통합화된 접근제어알고리즘의 보장하에서 정보관리 안전성을 확보하는 시스템 설계가 가능하다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권2호
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• pp.565-586
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• 2022

Cloud storage's elastic expansibility not only provides flexible services for data owners to store their data remotely, but also reduces storage operation and management costs of their data sharing. The data outsourced remotely in the storage space of cloud service provider also brings data security concerns about data integrity. Data integrity verification has become an important technology for detecting the integrity of remote shared data. However, users without data access rights to verify the data integrity will cause unnecessary overhead to data owner and cloud service provider. Especially malicious users who constantly launch data integrity verification will greatly waste service resources. Since data owner is a consumer purchasing cloud services, he needs to bear both the cost of data storage and that of data verification. This paper proposes a verification control algorithm in data integrity verification for remotely outsourced data. It designs an attribute-based encryption verification control algorithm for multiple verifiers. Moreover, data owner and cloud service provider construct a common access structure together and generate a verification sentinel to verify the authority of verifiers according to the access structure. Finally, since cloud service provider cannot know the access structure and the sentry generation operation, it can only authenticate verifiers with satisfying access policy to verify the data integrity for the corresponding outsourced data. Theoretical analysis and experimental results show that the proposed algorithm achieves fine-grained access control to multiple verifiers for the data integrity verification.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.48-48
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• 2000

We developed a wireless communication system for multiple instrumentation system. The developed system has a function of remote instrumentation and PLC(Programmable Logic Controller) control. The system consists of CC(Control and Communication) protocol, wireless media access and physical media system. For multiple wireless communication, we propose a hub polling protocol based on master-slave control concept. To show the validity of the developed system, several experiments are illustrated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2619-2621
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• 2001

This study proposes a new efficient MAC(media access control) protocol to establish the ultrasonic communication network for under water vehicles, which ensures a certain level of maximum throughput regardless of the propagation delay of ultrasonic and allows fast data transmission through the multiple ultrasonic communication channel. In this study, a media access control protocol for underwater communication network that allows 'peer-to-peer' communication between a surface ship and multiple underwater system is designed, and the proposed control protocol is implementde for its verification.

• Journal of Information Processing Systems
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• 제13권3호
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• pp.630-642
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• 2017

In this paper, we propose the opportunistic non-orthogonal multiple access (NOMA)-based cooperative relaying system (CRS) with channel state information (CSI) available at the source, where CSI for the source-to-destination and source-to-relay links is used for opportunistic transmission. Using the CSI, for opportunistic transmission, the source instantaneously chooses between the direct transmission and the cooperative NOMA transmission. We provide an asymptotic expression for the average achievable rate of the opportunistic NOMA-based CRS under Rayleigh fading channels. We verify the asymptotic analysis through Monte Carlo simulations, and compare the average achievable rates of the opportunistic NOMA-based CRS and the conventional one for various channel powers and power allocation coefficients used for NOMA.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2018년도 추계학술발표대회
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• pp.880-881
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• 2018

Recently technological advancements have allowed visible, infrared and thermal imaging systems to be readily available for security and access control. Increasing applications of facial recognition for security and access control leads to emerging spoofing methodologies. To overcome these challenges of occlusion, replay attack and disguise, researches have proposed using multiple imaging modalities. Using infrared and thermal modalities alongside visible imaging helps to overcome the shortcomings of visible imaging. In this paper we review and propose hybrid feature extraction methods to combine data from multiple imaging systems simultaneously.

• 전기전자학회논문지
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• 제17권4호
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• pp.492-498
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• 2013

최근 스마트폰 이용자가 급증하여 다양한 스마트폰 게임이 출시되고 있으나, 개인을 위한 게임이 주종을 이루고 함께할 수 있는 게임은 많지 않다. 본 논문에서는 하나의 게임을 다수 이용자와 같이 할 수 있도록 도와주는 블루투스를 이용한 다중접속 시스템을 제안한다. 제안 시스템은 기존 PC게임의 한계를 극복하고, Nintendo Wii와 같은 고가의 장비 없이 다수의 사용자가 함께 게임을 즐길 수 있는 방법을 편리하게 제공한다.

• Journal of information and communication convergence engineering
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• 제5권2호
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• pp.88-92
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• 2007

In this paper, an SS-RRA protocol that is based on Code Division Multiple Access is proposed and analyzed under the integrated voice and data traffic load. The backward logical channels consist of slotted time division frames with multiple spreading codes per slot. The protocol uses a reservation mechanism for the voice traffic, and a random access scheme for the data traffic. A discrete-time, discrete-state Markov chain is used to evaluate the performance. The numerical results show that the performance can be significantly improved by a few distinct spreading codes.

• Journal of Communications and Networks
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• 제8권3호
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• pp.313-322
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• 2006

We consider a power controlled code division multiple access (CDMA) system with multiple flow types. At each of the N nodes, there are F flow types with different signal-to-interference-and-noise-ratio (SINR) requirements. To keep the complexity of the transmitter low, we assume that each node uses the same power level for all its flows. The single flow case has been fully solved and is well-understood. We concentrate on the multiple flow case, and use a novel and different approach. For the uplink problem with N = 2 and F arbitrary, the necessary and sufficient conditions to have a solution are found and proved. For the general N > 1 uplink problem, we provide a necessary condition for the problem to have a solution and an iterative algorithm to find the optimum solution. For the downlink case with F > 1 some properties of the optimal sequences are obtained.