• 한국통신학회논문지
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• 제37A권10호
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• pp.876-884
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• 2012

본 논문에서는 무선 센서네트워크(wireless sensor network : WSN)에서 발생하는 두 가지 지연 요인인 큐잉 지연(queueing delay)과 랜덤 링크 스케줄링에 의한 지연(delay by random link scheduling)을 소개하고 이를 해결하기 위한 새로운 순차적 스케줄링 기법을 제안한다. 또한 모의 실험을 통하여 이용하여 제안한 다중 홉 전송기법의 성능 평가를 수행하고, 이를 기존의 랜덤 링크 스케줄링 기법의 성능과 종단간 패킷 전송 지연의 관점에서 비교한다. 모의실험 결과에 따르면, 소스 노드(source node)와 목적지 노드(destination node) 사이의 홉 수(hop distance)가 증가할수록 제안한 스케줄링 기법과 기존의 랜덤 링크 스케줄링 기법의 지연 성능 차이가 증가함을 알 수 있었다. 소스 노드와 목적지 노드 사이의 평균 홉 수가 2.66, 4.1, 4.75 및 6.3 일 때, 제안한 스케줄링 기법은 기존의 랜덤 링크 스케줄링 기법에 비해 22%, 36%, 48% 및 55% 까지 지연 시간을 줄일 수 있었다.

• 한국운동역학회지
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• 제34권2호
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• pp.93-103
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• 2024

Objective: The purpose of this study was to investigate whether dancers with chronic ankle instability (CAI) exhibit different characteristics in dynamic postural control ability and ankle joint laxity compared to dancers without CAI and non-dancers with CAI. Method: Twelve dancers with CAI, 14 dancers without CAI, and 12 non-dancers with CAI participated in the study. Dynamic balance was evaluated using the Star Excursion Balance Test (SEBT) and the single-leg hop balance. The laxity of the ankle joint was evaluated through the anterior drawer test and the talar tilt test. SEBT measured maximum reach distances in anterior, posteromedial, and posterolateral directions. Single-leg hop assessed center of pressure (COP) and time-to-boundary (TTB) outcomes. One-way ANOVA and Chi-square tests were performed to compare the outcome variables among the three groups. Results: Dancers with CAI demonstrated greater reach distance in the posterolateral direction compared to non-dancers with CAI during SEBT (p=.014). Secondly, dancers without CAI showed greater reach distance in the posterolateral (p<.001) and posteromedial (p=.001) directions during SEBT compared to non-dancers with CAI. Additionally, dancers without CAI exhibited better postural control with higher TTB AP mean of minima (p=.003) and TTB AP standard deviation of minima (p=.012) during single-leg hop compared to nondancers with CAI. Thirdly, dancers with CAI showed a lower positive rate during the anterior drawer test compared to non-dancers with CAI (p=.019). Conclusion: Dancers with CAI demonstrated better ankle function and reduced mechanical instability compared to non-dancers with CAI. Therefore, to elucidate the underlying mechanisms of lateral ankle sprain and CAI development exacerbation in dancers, additional factors that can affect ankle sprain, such as visual dependence during postural control and evaluation in dance movements, should be explored.

• 한국멀티미디어학회논문지
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• 제19권5호
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• pp.910-917
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• 2016

Sensors have limited resources in sensor networks, so efficient use of energy is important. Representative clustering methods, LEACH, LEACHC, TEEN generally use direct transmission methods from cluster headers to the sink node to pass collected data. However, the communication distance of the sensor nodes at low cost and at low power is not long, it requires a data transfer through the multi-hop to transmit data to the sink node. In the existing cluster-based sensor network studies, cluster process and route selection process are performed separately in order to configure the routing path to the sink node. In this paper, in order to use the energy of the sensor nodes that have limited resources efficiently, a cluster-based multi-hop routing protocol which merges the clustering process and routing process is proposed. And the proposed method complements the problem of uneven cluster creation that may occur in probabilistic cluster methods and increases the energy efficiency of whole sensor nodes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.206-208
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• 2005

Wireless sensor network's value has increased greatly in recent years in the fields of Ubiquitous Computing that function as solution to reduce both the limitation and collision about RFID Technology. The research for wireless sensor network technology is proceeding with the research for various sensor nodes, powerful routing algorithms, securities for data transmission, and valid applications. This paper suggests that we make the new multi-hop routing algorithm using RSS in order to implement enhanced multi-hop routing algorithm. This paper should demonstrate that the routing algorithm using suggested RSS is superior to routing algorithm based on established BSDV(Destination Sequenced Distance Vector).

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2003년도 추계학술발표논문집 (중)
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• pp.1229-1232
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• 2003

Ad Hoc 네트워크에서 on demand 라우팅 프로토콜로 대표적인 AODV(Ad Hoc On Demand Distance Vector Routing)는 table driven 기반의 라우팅 프로토콜과 비교해 active route만을 라우팅 테이블에 저장하기 때문에 오버헤드가 작고 경로단절시 경로복구를 통해 경로 재설정할 수 있는 장점을 가지고 있으나 경로복구시 대역폭 낭비가 심하고 복구시간이 길다는 drawback을 가지고 있다. 이러한 단점은 많은 라우팅 패킷의 발생으로 기인하는 점이 있다. 본 논문에서는 Expanding Ring Search 알고리즘에서 time out은 timestamp를 이용하여 네트워크 상황에 맞게 가변적으로 적용하는 알고리즘을 개선하여 hop 수에 따라 node traversal time을 설정하도록 제안하였다. 제안한 알고리즘은 시뮬레이션을 통하여 검증하였으며 라우팅 패킷의 발생을 줄이고 throughput에서 향상을 보였다.

• 한국항공운항학회지
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• 제21권1호
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• pp.15-22
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• 2013

In oceanic flight routes, HF radio and satellite data links have weather restrictions, long propagation delay and low data throughput. In this paper, we propose oceanic aeronautical communications scheme in the VHF band based on ad-hoc communication. The proposed scheme organizes autonomously a multi-hop network that is divided into multiple local network using aircraft to fly long-distance communication and supports a hybrid type of multiple access, which consists of random access and TDMA (Time Division Multiple Access) scheme. In addition, several algorithms to apply spatial reuse of transmission to multi-hop long range communication environments have been proposed. The proposed system proves performance improvement on delay time as an effective solution to communicate end-to-end on the oceanic flight routes and strengthens the reliability of oceanic aeronautical communication.

• International Journal of Computer Science & Network Security
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• 제21권3호
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• pp.165-171
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• 2021

Vehicular Ad hoc Network (VANET) is an extension paradigm of moving vehicles to communicate with wireless transmission devices within a certain geographical limit without any fixed infrastructure. The vehicles have most important participation in this model is usually positioned quite dimly within the certain radio range. Fuzzy based multi-hop broadcast protocol is better than conventional message dissemination techniques in high-mobility VANETs, is proposed in this research work. Generally, in a transmission range the existing number of nodes is obstacle for rebroadcasting that can be improved by reducing number of intermediate forwarding points. The proposed protocol stresses on transmission of emergency message projection by utilization subset of surrounding nodes with consideration of three metrics: inter-vehicle distance, node density and signal strength. The proposed protocol is fuzzy MHB. The method assessment is accomplished in OMNeT++, SUMO and MATLAB environment to prove the efficiency of it.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권10호
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• pp.2732-2749
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• 2023

Device-to-Device (D2D) communication has received increasing attention and been studied extensively thanks to its advantages in improving spectral efficiency and energy efficiency of cellular networks. This paper proposes a novel relay selection algorithm for multi-hop full-duplex D2D communications underlaying cellular networks. By selecting the relay of each hop in a reverse manner, the proposed algorithm reduces the heavy signaling overhead that traditional relay selection algorithms introduce. In addition, the social domain information of mobile terminals is taken into consideration and its influence on the performance of D2D communications studied, which is found significant enough not to be overlooked. Moreover, simulations show that the proposed algorithm, in absence of social relationship information, improves data throughput by around 70% and 7% and energy efficiency by 64% and 6%, compared with two benchmark algorithms, when D2D distance is 260 meters. In a more practical implementation considering social relationship information, although the proposed algorithm naturally achieves less throughput, it substantially increases the energy efficiency than the benchmarks.

• 정보처리학회논문지C
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• 제14C권2호
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• pp.191-198
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• 2007

이동성을 가진 다수의 노드들로 구성된 MANET (Mobile Ad-hoc Networks)에서는 네트워크 토폴로지의 빈번한 변화에 효과적으로 대응할 수 있는 요구기반 (On Demand) 방식의 라우팅 프로토콜이 주로 사용된다. 대표적인 요구기반 라우팅 프로토콜인 AODV (Ad-hoc On demand Distance Vector)는 데이터 전송을 위하여 경로의 다음노드 (Next Hop)가 기록된 각 노드의 경로테이블을 기반으로 운영되며 선정된 경로는 유효기간이 만료되거나 경로단절이 발생되지 않을 경우에 그대로 유지된다. 본 연구에서는 AODV를 기반으로 설정된 경로의 2홉 범위 내에서 동적 경로변경을 제공하는 부분적응형 경로유지 기법 (AODV PA)을 제안한다. 제안된 기법은 경로탐색 과정에서 경로의 다음노드 뿐 아니라 다음노드의 다음노드 (즉, 2홉 다음노드) 정보를 취득하여 상황에 따라 보다 효율적인 경로를 선택할 수 있도록 하며 이러한 경로변경으로 인한 예기치 못한 경로단절 발생을 막기 위하여 HELLO 메시지를 통한 부가적인 경로테이블 관리를 수행한다. NS 2를 이용한 시뮬레이션 결과는 제안된 기법이 기존의 AODV 보다 패킷 전달비율, 지연시간, 라우팅부하 측면에서 향상된 성능을 제공함을 보여준다.

• 한국산업정보학회논문지
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• 제17권7호
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• pp.1-8
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• 2012

본 논문에서는 유비쿼터스 환경 구축을 위한 센서 네트워크에서 효율적으로 데이터를 전송할 수 있는 멀티홉(multi-hop) 릴레이 (Relay) 전송 시스템을 고려한다. ISM 주파수 대역을 사용하는 DBO-CSS (Differentially Bi-Orthogonal Chirp Spread Spectrum) 방식의 확산대역 신호 중 하나인 첩 (Chirp) 신호를 이용하여 구축된 센서 네트워크를 기반으로 센서 거리 및 사물 위치인식을 위한 효율적인 릴레이 프로토콜을 제안한다. 효율적인 네트워킹 접속을 위하여 Zone information packet, Hop information packet, Tag information packet 및 Application serial packet 의 4종류의 패킷구조를 설계하여 구현하였으며, 구축된 센서 네트워크를 기반으로 사물의 위치인식의 효율성을 높이기 위한 구현 알고리즘을 제안하였다. 최종적으로 $15m{\times}15m$ 멀티셀 및 10 홉으로 구성된 테스트베드 시스템에서 제안한 프로토콜의 성능의 우수성을 검증한다.