• Journal of Communications and Networks
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• 제14권4호
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• pp.434-442
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• 2012

Several gateway selection schemes have been proposed that select gateway nodes based on a single Quality of Service (QoS) path parameter, for instance path availability period, link capacity or end-to-end delay, etc. or on multiple non-QoS parameters, for instance the combination of gateway node speed, residual energy, and number of hops, for Mobile Ad hoc NETworks (MANETs). Each scheme just focuses on the ment of improve only a single network performance, i.e., network throughput, packet delivery ratio, end-to-end delay, or packet drop ratio. However, none of these schemes improves the overall network performance because they focus on a single QoS path parameter or on set of non-QoS parameters. To improve the overall network performance, it is necessary to select a gateway with stable path, a path with themaximum residual load capacity and the minimum latency. In this paper, we propose a gateway selection scheme that considers multiple QoS path parameters such as path availability period, available capacity and latency, to select a potential gateway node. We improve the path availability computation accuracy, we introduce a feedback system to updated path dynamics to the traffic source node and we propose an efficient method to propagate QoS parameters in our scheme. Computer simulations show that our gateway selection scheme improves throughput and packet delivery ratio with less per node energy consumption. It also improves the end-to-end delay compared to single QoS path parameter gateway selection schemes. In addition, we simulate the proposed scheme by considering weighting factors to gateway selection parameters and results show that the weighting factors improve the throughput and end-to-end delay compared to the conventional schemes.

• 한국인터넷방송통신학회논문지
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• 제11권4호
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• pp.9-16
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• 2011

본 논문에서는 이동망에서 통신노드가 다이나믹하게 이동하는 경우, VLC 음성품질을 위지하기 위한 상호연동 구조를 다룬다. 연동구조에서 체계적인 품질 분석은 OPENT 시뮬레이터를 사용하였으며, 패킷지연율과 성능분석으로 결과를 제시하였다. 실험결과에 따라 이동노드의 수가 작을 때, PDR은 상대적으로 데이터 프래픽이 증가함에 따라 안정을 유지하며, 성능은 이동노드의 수에 영향을 받는다. 특히 MANET 노드 밀도가 크게 증가하면, 성능은 높아지지만 이동속도에 영향을 받지 않았다. 또한 FTP 업다운 응답시간은 이동속도와 노드의 수에 크게 영향을 주지 않음을 확인하였다.

• BMB Reports
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• 제39권1호
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• pp.55-60
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• 2006

We describe a phage display strategy, based on the differential resistance of proteins to denaturant-induced unfolding, that can be used to select protein variants with improved conformational stability. To test the efficiency of this strategy, wild-type and two stable variants of ${\alpha}_1$-antitrypsin (${\alpha}_1AT$) were fused to the gene III protein of M13 phage. These phages were incubated in unfolding solution containing denaturant (urea or guanidinium chloride), and then subjected to an unfavorable refolding procedure (dialysis at $37^{\circ}C$). Once the ${\alpha}_1AT$ moiety of the fusion protein had unfolded in the unfolding solution, in which the denaturant concentration was higher than the unfolding transition midpoint ($C_m$) of the ${\alpha}_1AT$ variant, around 20% of the phage retained binding affinity to anti-${\alpha}_1AT$ antibody due to a low refolding efficiency. Moreover, this affinity reduced to less than 5% when 10 mg/mL skimmed milk (a misfolding-promoting additive) was included during the unfolding/refolding procedure. In contrast, most binding affinity (>95%) remained if the ${\alpha}_1AT$ variant was stable enough to resist unfolding. Because this selection procedure does not affect the infectivity of M13, the method is expected to be generally applicable to the high-throughput screening of stable protein variants, when activity-based screening is not possible.

• 대한전자공학회논문지TC
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• 제42권12호
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• pp.149-158
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• 2005

본 논문은 고정대역 네트워크에서 최대 TCP 혼잡윈도우를 제한하여, 버퍼 크기와 무관하게 안정적인 성능과 전송률을 제공할 수 있는 혼잡회피 알고리즘을 제안한다. 현재는 AIMD(Additive Increase, Multiplicative Decrease) 기반의 혼잡제어 방법이 가장 널리 사용되고 있다. 그러나 AIMD 기반의 TCP 혼잡제어 방법은 고정대역 네트워크에서 불필요하게 성능을 저하시키는 문제가 있다는 것이 여러 연구결과를 통해 알려져 있다. 또한 TCP의 톱니파형 데이터율로 안정적인 데이터 전송률이 필요한 응용에 적용하기 어렵다. 제안된 알고리즘은 필요에 따라 공평성을 유지하며 혼잡에 의한 손실을 방지하기 위해 혼잡윈도우의 크기를 제한한다. 최대 혼잡윈도우의 크기를 병목노드에서 데이터 축적을 방지하는 지연 정보로 결정하여, 별도의 버퍼와 윈도우 제어절차 없이 연결의 성능과 전송율이 안정적이도록 한다. 다양한 경우에 대한 시뮬레이션을 통해 호환성, 정상상태의 성능, 정상상태 손실 패킷 수, 그리고 혼잡윈도우의 분산 등으로 특성을 검증하였다. 제안된 방법은 송신단의 간단한 수정으로 적용이 가능하며, 네트워크 라우터와 사용자 프로그램의 수정이 불필요하여 확산이 용이한 장점을 가지며, 고정대역 네트워크로 볼 수 있는 국내 초고속인터넷 접속망에 적용하면 성능개선을 얻을 수 있다.

• 정보보호학회논문지
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• 제34권1호
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• pp.129-141
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• 2024

디지털 전환이 다양한 분야에서 가속되고 있는 가운데, 금융시장에서도 디지털·전자화된 화폐를 포함한 지급결제 수단 발전에 관한 관심이 집중되고 있다. 그중 중앙은행 디지털화폐(Central Bank Digital Currency, CBDC)는 기존 실물 화폐를 대체할 수 있는 미래 디지털화폐로 가치변동이 없으며 기존 실물 화폐인 현금과1:1 등가교환이 가능하다. 최근 국내·외에서는 CBDC 출시를 위해 다양한 연구 및 개발을 진행하고 있다. 그러나, 현재 CBDC 시스템은 대용량 거래에 대한 처리 속도 지연, 응답대기시간 지연 및 네트워크 부하 등 CBDC 확장성에 관한 문제가 존재한다. 범용적인 CBDC 시스템을 구축하기 위해서는 기존 블록체인의 낮은 처리량 및 네트워크 부하 문제 등의 확장성 문제를 해결해야 한다. 따라서, 본 연구에서는 범용 CBDC 구축을 위한 강화학습 기반의 CBDC 환경에서 대용량 데이터에 대한 처리량 및 네트워크 부하 문제 해결 기술을 제안한다. 제안 기술은 기존 시스템 대비 최대 64배 이상의 처리량 증대 및 20% 이상의 네트워크 부하를 감소할 수 있다.

• Journal of Information Processing Systems
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• 제13권3호
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• pp.500-517
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• 2017

In this paper, an improved zone-based routing protocol for heterogeneous wireless sensor networks is proposed. The proposed protocol has fixed the sized zone according to the distance from the base station and used a dynamic clustering technique for advanced nodes to select a cluster head with maximum residual energy to transmit the data. In addition, we select an optimal route with minimum energy consumption for normal nodes and conserve energy by state transition throughout data transmission. Simulation results indicated that the proposed protocol performed better than the other algorithm by reducing energy consumption and providing a longer network lifetime and better throughput of data packets.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권5호
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• pp.475-491
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• 2009

This paper is primarily concerned with multi-path routing in Mobile Ad hoc Networks (MANETs). We propose a novel associativity-based on-demand source routing protocol for MANETs that attempts to establish relatively stable path(s) between the source and the destination. We introduce a new notion for gauging the temporal and spatial stability of nodes, and hence the paths interconnecting them. The proposed protocol is compared with other unipath (DSDV and AODV) and multi-path (AOMDV) routing protocols. We investigate the performance in terms of throughput, normalized routing overhead, packet delivery ratio etc. All on-demand protocols show good performance in mobile environments with less traffic overhead compared to proactive approaches, but they are prone to longer end-to-end delays due to route discovery and maintenance.

• 전기학회논문지
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• 제58권12호
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• pp.2505-2510
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• 2009

Semiconductor processes need measurement to confirm where there are problems in quality after progresses manufacturing process. This paper suggests equipment and automatic measure sampling method that control monitoring ratio according to change point occurrence availability of process that is not measure method by the existent simple ratio rate. This paper defines measure section as ailment section, metastable section and stability section by change point standard and create statistical model of each section and developed suitable measure rate model by section. As a result, we have accomplished maximum throughput and minimum sampling number that needs to maintain constant level of quality. Proposed method minimizes load of measure process by brings production quality sophistication and decrease of process badness and lowers measure rate in stable section making perception about problem occurrence quick heightening measure rate at change point occurrence.

• Journal of Communications and Networks
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• 제5권3호
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• pp.202-214
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• 2003

The central challenge in the design of ad-hoc networks is the development of dynamic routing protocol that efficiently finds route between mobile nodes. Several routing protocols such as DSR, AODV and DSDV have been proposed in the literature to facilitate communication in such dynamically changing network topology. In this paper, a Node Transition Probability (NTP) based routing algorithm, which determines stable routes using the received power from all other neighboring nodes is proposed. NTP based routing algorithm is designed and implemented using Global Mobile Simulator (GloMoSim), a scalable network simulator. The performance of this routing algorithm is studied for various mobility models and throughput, control overhead, average end-to-end delay, and percentage of packet dropped are compared with the existing routing protocols. This algorithm shows acceptable performance under all mobility conditions. The results show that this algorithm maximizes the bandwidth utilization during heavy traffic with lesser overhead.

• 한국소음진동공학회논문집
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• 제16권4호
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• pp.366-371
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• 2006

As functional requirements of automatic office machines like printers, Automatic Tellex Machines(ATMs), copying machines are on a trend for the higher speed and precision, extensive technical advances are being developed and implemented in the industry. Media transport system is a device to convey a sheet of paper in ATMs and printers. The stability of media transport system is a matter of concern as their operating throughput rapidly increases. And defects of belts or rollers in a transport system directly affect the level of stability of the system. Therefore an automatic diagnostic system for predicting various defects is necessary for the stable operation of the media transport system. A simulation based on multi-body dynamics has been done for a feasibility study of a system design for the defect anticipation.