• 농촌계획
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• 제23권1호
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• pp.1-10
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• 2017

네트워크를 분석하는 방법인 stochastic 기반의 community bridge node finder는 네트워크 구조의 일부 정보만을 이용하여 중심지 및 확산 경로의 유추가 가능하다. 그러나, heterogeneity 네트워크에 적용하기 어려운 단점을 보유하고 있어, 본 연구에서는 이를 개선하고자 하였다. heterogeneity 네트워크에 적용할 수 있는 community bridge node finder 방법을 개발하기 위해 네트워크의 modularity를 계측하는 방법을 적용하였으며, 개선된 방법을 통해 community bridge node를 정량적으로 평가할 수 있어 heterogeneity 네트워크의 분석이 가능하였다. 농촌계획분야 정보의 경우, 대부분 자료의 불확실성이 존재하며 무결성이 떨어지는 특성을 가지고 있는 바 본 연구에서 적용한 전염병 확산 예측 뿐만 아니라 개선된 방법을 활용할 경우 주산지 정비 거점 분석 등 다양한 형태로 이용될 수 있을 것으로 기대된다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2009년도 춘계학술발표대회
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• pp.1253-1256
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• 2009

본 연구에서는 무선 센서 네트워크에서 공용 주파수 대역 2.4GHz를 여러 무선 프로토콜이 사용함으로 발생하는 간섭 및 충돌에 의한 전송 성능 저하 문제를 해결하기 위한 방법으로 무선 센서 네트워크의 일부 센서 노드들을 Wired Bridge Node로 연결하는 방법을 제안한다. 이를 증명하기 위해, 무선 통신과 유선 통신을 동시에 지원하는 Wired and Wireless MAC을 포함하는 센서 노드인 Wired Bridge Node의 소프트웨어 구조를 제안하고 이 시스템을 검증하였다.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.525-543
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• 2010

Testing and validation processes are critical tasks in developing a new hardware platform based on a new technology. This paper describes a series of experiments to evaluate the performance of a newly developed MEMS-based wireless sensor node as part of a wireless sensor network (WSN). The sensor node consists of a sensor board with four accelerometers, a thermometer and filtering and digitization units, and a MICAz mote for control, local computation and communication. The experiments include calibration and linearity tests for all sensor channels on the sensor boards, dynamic range tests to evaluate their performance when subjected to varying excitation, noise characteristic tests to quantify the noise floor of the sensor board, and temperature tests to study the behavior of the sensors under changing temperature profiles. The paper also describes a large-scale deployment of the WSN on a long-span suspension bridge, which lasted over three months and continuously collected ambient vibration and temperature data on the bridge. Statistical modal properties of a bridge tower are presented and compared with similar estimates from a previous deployment of sensors on the bridge and finite element models.

• Interaction and multiscale mechanics
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• 제4권4호
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• pp.273-289
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• 2011

The vibration response of the bridges under the moving vehicular load is of importance for engineers to estimate the serviceability of existing bridges and to design new bridges. This paper deals with the three dimensional vibration analysis of prestressed concrete bridges under moving vehicles. The prestressed bridges are modeled by four-node isoparametric flat shell elements with the transverse shearing deformation taken into account. The usual five degrees-of-freedom (DOFs) per node of the element are appended with a drilling DOF to accommodate the transformation of the local stiffness and mass matrices to the global coordinates. The vehicle is modeled as a single or two-DOF system. A single-span prestressed Tee beam and two-span prestressed box-girder bridge are studied as the two numerical examples. The effects of prestress forces on the natural frequencies and dynamic responses of the bridges are investigated.

• Structural Engineering and Mechanics
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• 제38권4호
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• pp.417-428
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• 2011

This paper presents recovering of missing vibration data of a bridge transmitted from wireless sensors. Kalman filter algorithm is adopted to reconstruct the missing data analytically. Validity of the analytical approach is examined through a field experiment of a bridge. Observations demonstrate that, even a part of recovered acceleration responses is underestimated in comparison with those responses taken from cabled sensors, dominant frequencies taken from the reconstructed data are comparable with those from cabled sensors.

• Smart Structures and Systems
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• 제9권2호
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• pp.145-164
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• 2012

In this paper, solar-powered, multi-scale, vibration-impedance sensor node on Imote2 platform is presented for hybrid structural health monitoring (SHM) in cable-stayed bridge. In order to achieve the objective, the following approaches are proposed. Firstly, vibration- and impedance-based hybrid SHM methods are briefly described. Secondly, the multi-scale vibration and impedance sensor node on Imote2-platform is presented on the design of hardware components and embedded software for vibration- and impedance-based SHM. In this approach, a solar-powered energy harvesting is implemented for autonomous operation of the smart sensor nodes. Finally, the feasibility and practicality of the smart sensor-based SHM system is evaluated on a full-scale cable-stayed bridge, Hwamyung Bridge in Korea. Successful level of wireless communication and solar-power supply for smart sensor nodes are verified. Also, vibration and impedance responses measured from the target bridge which experiences various weather conditions are examined for the robust long-term monitoring capability of the smart sensor system.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.487-494
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• 2003

Recently it is used seismic analysis like single mode spectrum analysis, multi mode spectrum analysis and time history analysis in Korea. Because bridges are not special form of them but regular and simple form of them in our country, we must develope seismic analysis program of bridge based on single nude spectrum analysis. The program developed by this study reduces a Quantity and a time of calculation compared to SAP90 and gives accurate answers without errors. In the case of commercial program if we look for seismic load(P/sub e/(x)), we must increase the number of node and the larger the number of node the more a quantity and a time of calculation. But this program is exactly solved with basic node compared to commercial program.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권9호
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• pp.3615-3638
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• 2020

Node identity authentication is an essential means to ensure the security of the Internet of Things. Existing blockchain-based IoT node authentication schemes have many problems. A heterogeneous IoT node authentication scheme based on an improved hybrid blockchain is proposed. Firstly, the hybrid blockchain model is designed to make the blockchain and IoT environment more compatible. Then the proxy node selection mechanism is intended to establish a bridge between the ordinary IoT node and the blockchain, building by calculating the trust value between nodes. Finally, based on the improved hybrid blockchain, the node authentication scheme of the model and proxy node selection mechanism establishes a secure connection for communication between nodes. Safety and performance analysis shows proper safety and performance.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.127-132
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• 2008

As economic rapid growth, large structures are damaged by defects from design and construction process of the formation and environments. Therefore, safety diagnosis and monitoring skills are bringing importance into relief and legislate for safety diagnosis of large structures. However, the existing monitoring systems are difficult by using wire cable because of cost, error of date, location, revise. In this paper, wireless sensor network which are accelerator, temperature sensor system using ubiquitous had been field test on Sea-Hea Grand bridge. We compare accelerator, temperature sensor system with wire and wireless sensor network.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2004년도 추계학술대회 및 정기총회
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• pp.345-348
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• 2004

Every bridge node participating in multiple piconets and forming a scatternet should schedule the inter-piconet traffics in an efficient manner. Frequent piconet switching due to short polling intervals for the links of a bridge node leads to considerable time slots loss caused by the guard time and power consumption for transceiving and processing. On the other hand, restrained piconet switching may result in failures of fulfilling QoS (Quality of Service) requirements for some links. Tn this paper, we present a QoS aware inter-piconet scheduling scheme minimizing the piconet switching events within guaranteed QoS requirements. According to simulation results, the proposed scheme is confirmed to have great improvement in throughput and number of switching events over the credit scheme as current inter-piconet scheduling scheme for the scatter mode.