• Journal of the Optical Society of Korea
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• v.11 no.2
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• pp.59-62
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• 2007

In this paper, we introduce a reliable, scalable, and cost-effective switchless wavelength division multiplexing (WDM) network based on a quality-of-service supporting reservation-based medium access control (MAC) protocol. The protocol not only provides both packet and circuit switching but also supports multicasting. The network efficiency is significantly increased by spatially reusing wavelengths and exploiting multiple free spectral ranges (FSRs) of arrayed waveguide grating (AWG) employed in the architecture. We have demonstrated the feasibility of this architecture by simulating in $Optsim^{TM}$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.05a
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• pp.109-114
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• 1998

초고속 정보통신의 경제적인 구축을 위해서는 기존 통신망의 적절한 활용이 요구된다. 현재 국내에서는 PSTN, N-ISDN, 기업망 등 많은 독자적인 망들이 운용되고 있는데 비하여 이들 망의 점진적인 발전 및 초고속 통신망으로의 효율적인 통합운용이 절실히 요구되는 시점이다. 이러한 상황을 개선하기 위해, 초고속 통신망의 하부망으로서 경제적인 대안으로 관심을 끌고 있는 기존망의 하나가 CAIV 전송망의 일종인 HFC(Hybrid Fiber Coax)망 이다. 지금까지 HFC망은 주로 일반 통신 사업자 입장에서 보다는 CATV사업자들이 기 보유한 망을 통해서 통신과 방송의 통합 서비스를 경제적으로 제공하고자 하는 방안으로서 많은 관심을 끌고 있다. 본 논문에서는 HFC 구조에서 상향으로의 데이터 충돌이 발생했을 시 이 문제를 해결하기 위해 IEEE802.14에서 제안하는 MAC Protocol과 HFC망의 MAC프로토콜 구성요소 중 제안된 경합중재 알고리즘의 형태를 알아보고 이중 Tree algorithm을 분기율에 따라 성능을 평가하고자 한다.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.6
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• pp.335-344
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• 2011

The Tire Pressure Monitoring System(TPMS) is often used recently. However, the standards and functions are very different. Even though the regulation requires all vehicles install the TPMS, there is no a standard of a Physical and Media access control protocol which provides compatibility with other systems. In this paper, we propose a MAC protocol based on the international standard and an energy efficient hybrid RF system platform. The MAC protocol provides compatibility of the TPMS with other systems and the RF system platform reduces energy consumption significantly.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.4
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• pp.94-104
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• 2008

In this paper, we propose a new architecture of multiplier-and-accumulator (MAC) for high speed multiplication and accumulation arithmetic. By combining multiplication with accumulation and devising a hybrid type of carry save adder (CSA), the performance was improved. Since the accumulator which has the largest delay in MAC was removed and its function was included into CSA, the overall performance becomes to be elevated. The proposed CSA tree uses 1's complement-based radix-2 modified booth algorithm (MBA) and has the modified array for the sign extension in order to increase the bit density of operands. The CSA propagates the carries by the least significant bits of the partial products and generates the least significant bits in advance for decreasing the number of the input bits of the final adder. Also, the proposed MAC accumulates the intermediate results in the type of sum and carry bits not the output of the final adder for improving the performance by optimizing the efficiency of pipeline scheme. The proposed architecture was synthesized with $250{\mu}m,\;180{\mu}m,\;130{\mu}m$ and 90nm standard CMOS library after designing it. We analyzed the results such as hardware resource, delay, and pipeline which are based on the theoretical and experimental estimation. We used Sakurai's alpha power low for the delay modeling. The proposed MAC has the superior properties to the standard design in many ways and its performance is twice as much than the previous research in the similar clock frequency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.74-80
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• 2000

In this paper, we proposed the MAC protocol and analyzed the performance for CATV/LAN network which was based upon HFC(hybrid optic coaxial) increased abruptly as alternative method of high speed network. Upstream channel which analyzed very deeply for CATV/LAN network have the preferential access property depending upon that position and unidirectional property. To solve this fairness problem, we propose the CSMA-CD/U/P protocol that transm it as $P_i$ probability although data packets is immediately transmitted when it was occurred. As the analytic result and simulation, we obtained $P_i$ value and its average delay time. Also, we get its variance value and queue length distribution. The mean delay time and queue length increase as the load and number of stations increase in the CATV/LAN network.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.10
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• pp.152-160
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• 1994

Two dimensional interpolation filter for HD-MAC is designed with 1.0 .mu.m CMOS standard cells and verified by logic simulation. The interpolator uses FMH(FIR-Median Hybrid) filter. The median filter, which is the most complicated part of FMH filtre, is simply implemented by modifying Hadian-Sobel algorithm. the filter generates accurately the missed pixel data of luminance and chrominance with the worst case simulation condition at 27MHz clock rates.

• The Journal of the Korea Contents Association
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• v.2 no.3
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• pp.113-118
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• 2002

To provide interactive sonics in HFC(Hybrid Fiber Coax)-CATV network, there must be supported a MAC(Medium Access Control) protocol. It is wet known that collision can be occurred in the HFC upstream channel because it is shared by up to 500 users. Thus it needs the collision resolution algorithm. Consequently, this paper proposes the analysis mood to study stability of binary stack algorithm for adaptive collision resolution algorithm in HFC-CATV. Also, it compares a system throughput between IPP model and D-BMAP model.

• Electronics and Telecommunications Trends
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• v.11 no.4 s.42
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• pp.63-75
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• 1996

본 고에서는 일반 가정 및 소규모 업무용 가입자들에 대한 광대역화의 가장 경제적인 대안으로 관심을 끌고 있는 Hybrid fiber-coax 구조의 CATV 전송망에 대한 표준화 동향에 대해 조사 분석한 내용을 기술한다. HFC 액세스망에 대한 표준화는 IEEE 802.14 그룹, DAVIC, ATM Forum, IETF(Internet Engineering Task Force)와 Cable TV업계 등 여러기구에서 추진하고 있다. 지금까지 물리계층, MAC계층 등에 대한 주요 표준규격에 대해 DAVIC과 IEEE 802.14에서 주도하고 있으나, 앞으로는 데이터 서비스에 상대적 우선 순위를 두고 표준화를 추진하는 IEEE 802.14그룹에서 주도하게 될 것으로 보인다. 또한 인터넷 접속과 고속 데이터 서비스를 위한 인터페이스와 IP 접속 프로토콜에 대한 표준화를 발 빠르게 추진하고 있는 IETF와 MCNS(Multimedia Cable Network System) 등의 역할이 커질 것으로 전망된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.687-708
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• 2017

The machine-to-machine (M2M) communication is featured by tremendous number of devices, small data transmission, and large uplink to downlink traffic ratio. The massive access requests generated by M2M devices would result in the current medium access control (MAC) protocol in LTE/LTE-A networks suffering from physical random access channel (PRACH) overload, high signaling overhead, and resource underutilization. As such, fairness should be carefully considered when M2M traffic coexists with human-to-human (H2H) traffic. To tackle these problems, we propose an adaptive Slotted ALOHA (S-ALOHA) and time division multiple access (TDMA) hybrid protocol. In particular, the proposed hybrid protocol divides the reserved uplink resource blocks (RBs) in a transmission cycle into the S-ALOHA part for M2M traffic with small-size packets and the TDMA part for H2H traffic with large-size packets. Adaptive resource allocation and access class barring (ACB) are exploited and optimized to maximize the channel utility with fairness constraint. Moreover, an upper performance bound for the proposed hybrid protocol is provided by performing the system equilibrium analysis. Simulation results demonstrate that, compared with pure S-ALOHA and pure TDMA protocol under a target fairness constraint of 0.9, our proposed hybrid protocol can improve the capacity by at least 9.44% when ${\lambda}_1:{\lambda}_2=1:1$and by at least 20.53% when ${\lambda}_1:{\lambda}_2=10:1$, where ${\lambda}_1,{\lambda}_2$ are traffic arrival rates of M2M and H2H traffic, respectively.

• Journal of Communications and Networks
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• v.11 no.6
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• pp.615-625
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• 2009

Worldwide inter-operability for microwave access (WiMAX) is a promising technology that provides high data throughput with low delays for various user types and modes of operation. While much research had been conducted on physical and MAC layers, little attention has been paid to a comprehensive and efficient security solution for WiMAX. We propose a hybrid security solution combining identity-based cryptography (IBC) and certificate based approaches. We provide detailed message exchange steps in order to achieve a complete security that addresses the various kind of threats identified in previous research. While attaining this goal, efficient fusion of both techniques resulted in a 53% bandwidth improvement compared to the standard's approach, PKMv2. Also, in this hybrid approach, we have clarified the key revocation procedures and key lifetimes. Consequently, to the best of knowledge our approach is the first work that unites the advantages of both techniques for improved security while maintaining the low overhead forWiMAX.