• 한국정보통신학회논문지
• /
• 제10권6호
• /
• pp.1055-1059
• /
• 2006

무선 센서 네트워크의 센서 노드는 브로드캐스트 방식을 사용하여 수집한 데이터를 이웃한 다른 센서노드로 전달하기 때문에 데이터 중복성 문제가 발생한다. 데이터 중복성은 네트워크 로드를 가중시키며 데이터 손실의 원인이 되며, 이러한 문제점은 데이터 전송의 신뢰성과 네트워크 혼잡 회피간의 상충조건에 의해 발생한다. 따라서 무선 센서 네트워크에서 효율적으로 혼잡제어를 수행하기 위해서는 신뢰성 있는 전송(reliable transmission), 무선 손실(wireless loss), 혼잡 손실(congestion loss) 등과 같은 여러 요소를 고려한 신뢰성 있는 혼잡제어 기법이 필요하다. 본 논문에서는 Hop-by-Hop 순서 번호, DSbACK(Delayed and Selective ACK, Buffer Condition)을 사용하여 신뢰성 있는 전송을 보장하고 불필요한 전송을 최소화한 에너지 절약형 혼잡 제어 기법으로 HRCCP(Hop-by-Hop Reliable Congestion Control Protocol)를 제안하여 무선 센서 네트워크에서 신뢰성 있는 전송과 흔잡 제어가 동시에 이루어 질수 있도록 하였다.

• International Journal of Contents
• /
• 제12권1호
• /
• pp.65-69
• /
• 2016

Wireless communication chipsets have fixed transmission rate and communication distance. Although there are many kinds of chipsets with throughput and distance purpose, they cannot support various types of wireless applications. This paper provides theoretic research results in order to support various wireless applications requiring different throughput, delayed quality-of-service (QoS), and different communication distances by using a wireless communication chipset with fixed rate and transmission power. As a performance metric, the probability for a data frame that successfully receives at a desired receiver is adopted. Based on this probability, the average number of transmission in order to make a successful frame transmission is derived. Equations are utilized to analyze the performance of a single-hop with channel coding and a dual-hop without error correction matter transmission system. Our results revealed that single-hop transmission assisted by channel coding could extend its communication distance. However, communication range extending effect of the single-hop system was limited. Accordingly, dual-hop transmission is needed to overcome the communication distance limit of a chipset.

• 한국정보통신학회논문지
• /
• 제24권11호
• /
• pp.1550-1553
• /
• 2020

In this paper, we maximize the lifetime of a multi-hop path through a cooperative wireless energy sharing scheme between constituent nodes in a wireless multi-hop communication. Considering a bidirectional multi-hop communication environment, we present an optimization problem to maximize path lifetime by adjusting the amount of energy each node needs to share with its neighboring nodes. On the basis of solidarity property, i.e., the lifetime of the multi-hop path is maximized when the lifetimes of all nodes are the same, we convert the considered optimization problem into a linear programming problem and solve it easily. Simulation result shows that the proposed two-way wireless energy sharing method maximizes the path lifetime of multi-hop communications and approximately doubles the path lifetime compared with the one-way energy sharing method.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제16권2호
• /
• pp.405-423
• /
• 2022

The distance vector-hop (DV-Hop) is one of the emblematic algorithms that use node connectivity for locating, which often accompanies by a large positioning error. To reduce positioning error, the bio-inspired algorithm and weight optimization model are introduced to address positioning. Most scholars argue that the weight value decreases as the hop counts increases. However, this point of view ignores the intrinsic relationship between the error and weight. To address this issue, this paper constructs the relationship model between error and hop counts based on actual communication characteristics of sensor nodes in wireless sensor network. Additionally, we prove that the error converges to 1/6CR when the hop count increase and tendency to infinity. Finally, this paper presents a modified error-oriented weight positioning model, and implements it with genetic algorithm. The experimental results demonstrate excellent robustness and error removal.

• Journal of Plant Biology
• /
• 제20권1호
• /
• pp.59-61
• /
• 1977

This experiment was undertaken with the purpose of investigating the effect on the hop yield and dryweight of two Hallertau forma, Shinshuwase by Gibberellin treatment. The concentration of GA applied were 0, 10, 20ppm respectively and they were treated before ten day of flowering of hop. The result as follows; (1) Yield of hop was increased significantly by treatment of GA 10 ppm solution that is Hallertau was increased 17.2% of control plots, and Shinshuwase was increased 23.2% in GA 20ppm. (2) In dry weight was increased significantly by treatment of GA 10ppm solution that is Hallertau was increased 21.6% of control plot and Shinshuwase was increased 25.9% in GA 20ppm.

• 한국군사과학기술학회지
• /
• 제24권1호
• /
• pp.115-122
• /
• 2021

In this paper, we propose a dynamic slot allocation scheme to improve the slot utilization rate in tactical multi-hop networks in which the channel condition varies due to node movements. The proposed scheme takes advantage of the fact that nodes that are more than three hops apart can use the same slot simultaneously. The frame is divided into two parts: the control period and the data period. To know the available slot information within two-hop distance, the node exchanges a slot allocation information with one-hop neighbors during the control period. The node can get the information on idle slots that are not used within two-hop distance but assigned already to other nodes that are more than three-hop away. The identified idle slot can be used by the node, which increases the slot utilization rate. The performance analysis results of the proposed scheme show that it increases the slot utilization rate sufficiently despite the overhead of the control period in the multi-hop networks of the future soldier system.

• Journal of Communications and Networks
• /
• 제17권1호
• /
• pp.58-66
• /
• 2015

Aeronautical communication networks (ACN) is an emerging concept in which aeronautical stations (AS) are considered as a part of multi-tier network for the future wireless communication system. An AS could be a commercial plane, helicopter, or any other low orbit station, i.e., Unmanned air vehicle, high altitude platform. The goal of ACN is to provide high throughput and cost effective communication network for aeronautical applications (i.e., Air traffic control (ATC), air traffic management (ATM) communications, and commercial in-flight Internet activities), and terrestrial networks by using aeronautical platforms as a backbone. In this paper, we investigate the issues about connectivity, throughput, and delay in ACN. First, topology of ACN is presented as a simple mobile ad hoc network and connectivity analysis is provided. Then, by using information obtained from connectivity analysis, we investigate two communication models, i.e., single-hop and two-hop, in which each source AS is communicating with its destination AS with or without the help of intermediate relay AS, respectively. In our throughput analysis, we use the method of finding the maximum number of concurrent successful transmissions to derive ACN throughput upper bounds for the two communication models. We conclude that the two-hop model achieves greater throughput scaling than the single-hop model for ACN and multi-hop models cannot achieve better throughput scaling than two-hop model. Furthermore, since delay issue is more salient in two-hop communication, we characterize the delay performance and derive the closed-form average end-to-end delay for the two-hop model. Finally, computer simulations are performed and it is shown that ACN is robust in terms of throughput and delay performances.

• 패션비즈니스
• /
• 제2권1호
• /
• pp.86-99
• /
• 1998

The aim of this study to examine the Hip-Hop style, one of the fashion trends of the new generation in the 1990s and to come up with a design with a Hip-Hop image. As the Counterculture, Black Renaissance, Pop Star Syndrome, the importance of Hip-Hop fashion in mass culture was recognized and given a firm place as one of the major cultural trends of the 1990s. Hip-Hop fashion has a history: it originated from the Caribbean style in the 1940s and was transformed into Rude Boys style in the 1960s, Two-tone style and Rastafarians style in the 1970s. Finally it was succeeded by B-boys and Flygirls style. Hip-Hop style combines characteristics of all three styles mixed in one, which are as follows. First, Neo-Hip-Hop Fashion, Second, Hip-Hop Reggae Fashion and Third, Graffiti Fashion. Based on these three Hip-Hop images of the 19905, an attempt will be made to produce a Design Planning with a predicted 1998 fashion trend. This research provides order sheets on ready-made clothes designed for new generation in their late 10s and early 20s. Design Concept, Image Map, Fabric, color direction will be offered on the basis of an image map drawn in line with the three design concepts incorporating three sub themes of Liveliness, Modern Ethnic, and Dynamic Future. Three designs will be designed based on the following fashion themes$\ddot{o}$ Generation 'Y', Black Guys and Street Boys.

• Journal of Information Processing Systems
• /
• 제16권5호
• /
• pp.1158-1168
• /
• 2020

The distance vector-hop wireless sensor node location method is one of typical range-free location methods. In distance vector-hop location method, if a wireless node A can directly communicate with wireless sensor network nodes B and C at its communication range, the hop count from wireless sensor nodes A to B is considered to be the same as that form wireless sensor nodes A to C. However, the real distance between wireless sensor nodes A and B may be dissimilar to that between wireless sensor nodes A and C. Therefore, there may be a discrepancy between the real distance and the estimated hop count distance, and this will affect wireless sensor node location error of distance vector-hop method. To overcome this problem, it proposes a wireless sensor network node location method by modifying the method of distance estimation in the distance vector-hop method. Firstly, we set three different communication powers for each node. Different hop counts correspond to different communication powers; and so this makes the corresponding relationship between the real distance and hop count more accurate, and also reduces the distance error between the real and estimated distance in wireless sensor network. Secondly, distance difference between the estimated distance between wireless sensor network anchor nodes and their corresponding real distance is computed. The average value of distance errors that is computed in the second step is used to modify the estimated distance from the wireless sensor network anchor node to the unknown sensor node. The improved node location method has smaller node location error than the distance vector-hop algorithm and other improved location methods, which is proved by simulations.

• 한국통신학회논문지
• /
• 제32권12A호
• /
• pp.1226-1237
• /
• 2007

이 논문은 IEEE 802.16 기반의 무선 메쉬 네트워크를 위한 QoS 메쉬 라우팅 프로토콜을 제안한다. 본 논문에서 제안하는 QoS 메쉬 라우팅 프로토콜은 테이블 관리 (Table-driven or Proactive) 방식의 홉 간 (Hop-by-Hop) QoS 라우팅 프로토콜이다. 제안하는 라우팅 프로토콜의 목표는 송신 노드에서 목적지 노드까지 경로를 찾는 것 뿐만 아니라, 대역폭과 지연의 관점에서, QoS 요구사항을 만족시키는 최적 경로를 찾는 것이다. 이 논문에서, 우리는 먼저 이동 Ad Hoc 라우팅 프로토콜과 관련된 연구를 바탕으로, 라우팅 프로토콜의 유형을 분석하고, 테이블관리 방식의 홉 간 라우팅 프로토콜이 무선 메쉬 네트워크에 가장 적합함을 보인다. 그리고 나서, 본 논문에서 주목하는 IEEE 802.16 기반의 무선 메쉬 네트워크의 네트워크 모델을 소개하고, 테이블 관리 방식의 홉 간 라우팅 프로토콜을 기반으로 하는 QoS 메쉬 라우팅 프로토콜을 제안한다. 시뮬레이션을 통해서, 제안하는 라우팅 프로토콜이 QOLSR 프로토콜에 비하여 단대단 지연 (End-to-End Delay)이 낮고, 패킷 전달률 (Packet Delivery Ratio)이 높으며, 라우팅 오버헤드 패킷 량이 적음을 보였다.