• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권3호
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• pp.1357-1372
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• 2017

Energy harvesting techniques, particularly radio frequency energy harvesting (RF-EH) techniques, which are known to provide feasible solutions to enhance the performance of energy constrained wireless communication systems, have gained increasing attention. In this paper, we consider a wireless-powered cooperative communication network (WPCCN) for transferring energy in the downlink and forwarding signals in the uplink. The objective is to maximize the average transmission rate of the system, subject to the total network power constraint. We formulate such a problem as a form of wireless energy transmission based on resource allocation that searches for the joint subcarrier pairing and the time and power allocation, and this can be solved by using a dual approach. Simulation results show that the proposed joint optimal scheme can efficiently improve system performance with an increase in the number of subcarriers and relays.

• 한국컴퓨터정보학회논문지
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• 제24권5호
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• pp.1-9
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• 2019

In this paper, we propose the algorithms which determine 1) the efficient anchor-node visiting route of mobile sink in terms of energy supply and 2) the efficient energy amount to be charged to each anchor node, by using the information of each anchor node and the mobile sink. Wireless sensor networks (WSNs) using mobile sinks can be deployed in more challenging environments such as those that are isolated or dangerous, and can also achieve a balanced energy consumption among sensors which leads to prolong the network lifetime. Most mobile sinks visit only some anchor nodes which store the data collected by the nearby sensor nodes because of their limited energy. The problem of these schemes is that the lifetime of the anchor nodes can be shorten due to the increased energy consumption, which rapidly reduces the overall lifetime of WSN. This study utilizes a mobile sink capable of wireless power transmission to solve this problem, so a mobile sink can gather data from anchor nodes while charging energy to them. Through the performance verification, it is confirmed that the number of blackout nodes and the amount of collected data are greatly improved regardless of the size of the network.

• International journal of advanced smart convergence
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• 제6권1호
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• pp.50-56
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• 2017

Wireless sensor nodes have limited energy, so it is important to optimize energy consumption to preserve network lifetime. Various protocols have been proposed for this purpose. LEACH protocol and SEP are the representative protocols. These protocols become less effective as the Sensor Field becomes wider. To improve this, MR-SEP and L-SEP were proposed. These protocols increase the energy efficiency by dividing the Sensor Field into layers and reducing the transmission distance. However, when dividing a layer, there are cases where it is divided inefficiently, and a node within a certain range from a Base Station has a better transmission efficiency than a direct transmission method using a cluster method. In this paper, we propose a Single-hop layer for L-SEP to improve inefficient layer division and near node transmission efficiency. When the larger the Sensor Field, the better the performance of the proposed method by up to 87%. The larger the sensor field, the more efficient the proposed method is over the conventional method. That is, the proposed method is suitable for the wide Sensor Field.

• 조명전기설비학회논문지
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• 제15권2호
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• pp.64-72
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• 2001

본 논문에서는 비접촉 충전 에너지 전달을 위한 포워드 ZVS MRC(Zero Voltage Switching Multi Resonant Converter)를 제안하였다. 포워드 ZVS MRC는 기생성분을 흡수하는데 그리고 스위칭손실을 최소화하는데 효과적이다. 이것은 높은 주파수동작에 적합하며 따라서 이것을 비접촉 충전에너지 전달에 적용하였다. 사용된 컨버터는 분리형 트랜스포머와 동기식정류기를 이용하였다. 갭의 크기에 따른 결합계수(k), 누설인덕턴스, 결합인 덕턴스 그리고 공진 주파수를 측정하였다. 구해진 값을 이용하여 회로를 설계, 구현하였으며 제안된 회로는 PSPICE로 시뮬레이션하였고 실험하였다. 주스위치의 전압 스트래스와 출력전력을 측정하였으며 제안된 컨버터가 비접촉 충전 에너지 전달에 적합함을 보였다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 추계학술대회 논문집
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• pp.303-308
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• 2003

In this paper, wave numerical modeling was experimented for the analysis of impact factors for the wave transmission as the incident wave and topographic conditions in the narrow channel sea. Recently, Although the results of many researcher for the wave modelling, numerical equations have limited to simulation of wave transformation effects. Despite of thispresent problems, the models was used to design the coastal structures in barrow channel sites. Finally, this paper estimated the wave model(mild slope eq. model) as the analysis of the wave energy transmission according to changing of impact factors(width of channel, bottom slope in channel, incident wave angle, wave period). As the results of numerical experiment, the major impact factors which influence to wave energy transmission were the width of channel and incident wave direction. But in the case that the width of channel is larger than 3L(L=Length of wave), the reduction of wave energy was small.

• 한국소음진동공학회논문집
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• 제17권7호
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• pp.649-661
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• 2007

Friction-type reinforcing members(FRM) to enhance the resistance to wind loads of a transmission tower through both stiffness strengthening and damping increase are energy dissipation devices that utilize bending deflection of a tower leg. In this paper, the hysteretic behavior of the transmission tower structure with FRMs was experimentally investigated through cyclic loading tests on a half scale substructure model. Firstly, the variation of friction forces and durability of the FRM depending on the type of friction-inducing materials used in the FRM were examined by performing the cyclic loading tests on the FRM. Secondly, cyclic loading tests of a half-scale two-dimensional substructure model of a transmission tower with FRMs were conducted. Test results show that the FRM, of which desired maximum friction force is easily regulated by adjusting the amplitude of the torque applied to the bolts, have stable hysteretic behaviors and it is found that there exists the optimum torque depending on a design load by investigating the amount of energy dissipation of the FRMs according to the increase of torque.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.568-577
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• 2007

Friction-type reinforcing members (FRM) to enhance the resistance to wind loads of a transmission tower through both stiffness strengthening and damping increase are energy dissipation devices that utilize bending deflection of a tower leg. In this paper, the hysteretic behavior of the transmission tower structure with FRMs was experimentally investigated through cyclic loading tests on a half scale substructure model. Firstly, the variation of friction forces and durability of the FRM depending on the type of Friction-inducing materials used in the FRM were examined by performing the cyclic loading tests on the FRM. Secondly, Cyclic loading tests of a half-scale two-dimensional substructure model of a transmission tower with FRMs were conducted. Test results show that the FRM, of which desired maximum friction force is easily regulated by adjusting the amplitude of the torque applied to the bolts, have stable hysteretic behaviors and it is found that there exists the optimum torque depending on a design load by investigating the amount of energy dissipation of the FRMs according to the increase of torque.

• 한국통신학회논문지
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• 제41권4호
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• pp.433-440
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• 2016

본 논문에서는 사물인터넷 환경에서 통신 기기들이 정보를 직접 공유하고자 할 때 전체 네트워크의 에너지 소모량을 최소화하기 위한 방식을 제안한다. 제안하는 방식은 매 전송 시 동적으로 전송 노드 및 전송 데이터를 선택하는 효과적인 네트워크 부호화 기법을 사용하여 정보 공유에 필요한 총 전송 횟수를 감소시킨다. 실험을 통하여 기존의 고정된 순서로 전송 노드를 설정하는 네트워크 부호화 방식, 랜덤한 순서로 전송 노드를 설정하는 네트워크 부호화 방식, 그리고 랜덤한 순서로 전송 노드를 설정하는 비부호화 방식에 비해 총 전송 횟수 측면에서 보다 뛰어난 성능을 가짐을 확인하였다.

• 한국산업정보학회논문지
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• 제25권1호
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• pp.1-11
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• 2020

본 논문은 큰 스케일의 무선센서네트워크(Wireless Sensor Networks: WSN)에서 클러스터링을 위한 제어 메시지의 최적화된 전송반경을 사용하여 전체 네트워크의 수명을 증가시키는 방법을 제안한다. 또한 스케일이 큰 네트워크에서 노드들의 제어 메시지의 최대 전송반경과 에너지 소모에 대하여 고찰한다. 이를 위하여 일반 노드가 소모하는 에너지와 클러스터 헤드가 소모하는 에너지의 함수 형태로 제어 메시지 전송반경을 분석하고, 이를 바탕으로 최적의 전송반경을 구하는 방법을 제시한다. 제안한 방법을 이용하여 싱글 홉 및 멀티 홉 등의 여러 WSN 라우팅 환경에서 시행한 시뮬레이션 성능 분석 결과를 바탕으로, 본 논문에서 제안한 방법이 기존의 방법들에 비하여 전체 네트워크의 수명을 더욱 길게 운용하는 것을 보였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.166-171
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• 2002

The transmission loss coefficient is very important acoustic property in parallel with absorption and acoustic impedance categorizing the acoustical materials, which can control the acoustical problems. At the same time, the transmission loss coefficient is a key parameter to choose the optimum material for the analysis of acoustical characteristics of material using SEA(Statistical Energy Analysis). In this paper, the transmission loss coefficient measurement system using 4-microphone impedance tube is proposed, based on the idea calculating the full transfer matrix of the acoustical sample to test. The theoretical background and measurement system are introduced, and finally the measurement results are verified.