• 디지털산업정보학회논문지
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• 제10권1호
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• pp.39-45
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• 2014

This paper proposes an architecture of a sensor network for gathering data under a powerful beam cluster tree architecture. This architecture is used when there is a need to gather data from sensor node where there is no sink node connected to an existing network, or it is required to get a series of data specific to an event or time. The transmit distance of the beam signal is longer than that of the usual sensor node. The nodes of the network make a tree network when receiving a beam message transmitting from the powerful root node. All sensor nodes in a sink tree network synchronize to the superframe and know exactly the sequence value of the current superframe. When there is data to send to the sink node, the sensor node sends data at the corresponding allocated channel. Data sending schemes under the guaranteed time slot are tested and the delay and jitter performance is explained.

• Steel and Composite Structures
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• 제26권4호
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• pp.463-471
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• 2018

The bolted end-plate beam-column connections have been widely used in steel structure and composite structure because of its excellent seismic performance. In this paper, the end-plate bolted connection is applied in the concrete structure, A new-type of fabricated beam-column connections with end-plates is presented, and steel plate hoop is used to replace stirrups in the node core area. To study the seismic behavior of the joint, seven specimens are tested by pseudo-static test. The experimental results show that the new type of assembly node has good ductility and energy dissipation capacity. Besides, under the restraint effect of the high-strength stirrup, the width of the web crack is effectively controlled. In addition, based on the analysis of the factors affecting the shear capacity of the node core area, the formula of shear capacity of the core area of the node is proposed, and the theoretical values of the formula are consistent with the experimental value.

• Steel and Composite Structures
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• 제22권1호
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• pp.45-61
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• 2016

The domestic and foreign scholars conducted many studies on mechanical properties of wave web steel beam and high-strength spiral stirrups confined concrete columns. Based on the previous research work, studies were conducted on the anti-seismic property of the end plate bolt connected wave web steel beam and high-strength spiral stirrups confined concrete column nodes applied with pre-tightening force. Four full-size node test models in two groups were designed for low-cycle repeated loading quasi-static test. Through observation of the stress, distortion, failure process and failure mode of node models, analysis was made on its load-carrying capacity, deformation performance and energy dissipation capacity, and the reliability of the new node was verified. The results showed that: under action of the beam-end stiffener, the plastic hinges on the end of wave web steel beam are displaced outward and played its role of energy dissipation capacity. The study results provided reliable theoretical basis for the engineering application of the new types of nodes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제2권5호
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• pp.265-277
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• 2008

In spite of previous common assumptions about the incompatibility of public key cryptography (PKC) schemes with wireless sensor networks (WSNs), recent works have shown that they can be utilized for such networks in some manner. The major challenge of employing a PKC-based scheme in a wireless sensor network is posed by the resource limitations of the tiny sensors. Considering this sensor feature, in this paper we propose an efficient PKC-based security architecture with relatively lower resource requirements than those of previously proposed PKC schemes for WSN. In addition, our scheme aims to provide robust security in the network. Our security architecture comprises two basic components; a key handshaking scheme based on simple, linear operations and the derivation of a decryption key by a receiver node. Our architecture enables node-to-base-station and node-to-node secure communications. Analysis and simulation results show that our proposed architecture ensures a good level of security for network communications, and can be effectively implemented with the limited computational, memory, and energy budgets of current-generation sensor nodes.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 춘계학술대회
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• pp.286-289
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• 2016

본 논문에서는 오직 모바일 클라우드 컴퓨팅만을 사용하여 스마트폰 기반의 모바일 앱에서 Node.js 파일이 비동기 차단, 비 차단, 이벤트 기반 프로그램 패러다임을 제시한다. 또한 데이터베이스로 잘 알려진 MongoDB를 사용하여 App 사용자에 의해 전송된 방대한 데이터들을 처리한다. Node.js는 프로그래머가 동시 접속 문제를 해결하는 데 필요한 도구를 제공하는 것을 목표로 하고 있다. 원격 사용자들이 드라이버 입력을 전달하고 외부 응용 프로그램에서 출력을 제공하는 응용 프로그램을 고려하고 있는데, 차량을 이용하여 실시간으로 데이터를 분석 할 수 있는 스마트 폰 인터페이스 방식으로 응용 프로그램을 구현하여 제안 된 구조의 효과를 보여주고자 한다.

• ETRI Journal
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• 제30권1호
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• pp.13-20
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• 2008

We evaluate the sink capacity of wireless code division multiple access (CDMA) sensor networks with layered architecture. We introduce a model of interference at a sink considering two kinds of interference: multiple access interference (MAI) and node interference (NI). We also investigate the activity of sensor nodes around the sink in relation to gathering data under a layered architecture. Based on the interference model and the activity of sensor nodes around the sink, we derive the failure probability of the transmission from a source node located one hop away from the sink using Gaussian approximation. Under the requirement of 1% failure probability of transmission, we determine the sink capacity, which is defined as the maximum number of concurrent sensor nodes located one hop away from the sink. We demonstrate that as the node activity of the MAI decreases, the variation of the sink capacity due to the node activity of the NI becomes more significant. The analysis results are verified through computer simulations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권1호
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• pp.178-202
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• 2012

In this paper, we first survey cross-layer architectures for Wireless Sensor Networks (WSNs) and Wireless Multimedia Sensor Networks (WMSNs). Afterwards, we propose a novel cross-layer architecture for QoS provisioning in clustered and multi-hop based WMSNs. The proposed architecture provides support for multiple network-based applications on a single sensor node. For supporting multiple applications on a single node, an area in memory is reserved where each application can store its network protocols settings. Furthermore, the proposed cross-layer architecture supports heterogeneous flows by classifying WMSN traffic into six traffic classes. The architecture incorporates a service differentiation module for QoS provisioning in WMSNs. The service differentiation module defines the forwarding behavior corresponding to each traffic class. The forwarding behavior is primarily determined by the priority of the traffic class, moreover the service differentiation module allocates bandwidth to each traffic class with goals to maximize network utilization and avoid starvation of low priority flows. The proposal incorporates the congestion detection and control algorithm. Upon detection of congestion, the congested node makes an estimate of the data rate that should be used by the node itself and its one-hop away upstream nodes. While estimating the data rate, the congested node considers the characteristics of different traffic classes along with their total bandwidth usage. The architecture uses a shared database to enable cross-layer interactions. Application's network protocol settings and the interaction with the shared database is done through a cross-layer optimization middleware.

• Journal of Computing Science and Engineering
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• 제9권4호
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• pp.163-176
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• 2015

Self-organization of distributed wireless sensor nodes is a critical issue in wireless sensor networks (WSNs), since each sensor node has limited energy, bandwidth, and scalability. These issues prevent sensor nodes from actively collaborating with the other types of sensor nodes deployed in a typical heterogeneous and somewhat hostile environment. The automated self-organization of a WSN becomes more challenging as the number of sensor nodes increases in the network. In this paper, we propose a dynamic self-organized architecture that combines tree topology with a drawn-grid algorithm to automate the self-organization process for WSNs. In order to make our proposed architecture scalable, we assume that all participating active sensor nodes are unaware of their primary locations. In particular, this paper presents two algorithms called active-tree and drawn-grid. The proposed active-tree algorithm uses a tree topology to assign node IDs and define different roles to each participating sensor node. On the other hand, the drawn-grid algorithm divides the sensor nodes into cells with respect to the radio coverage area and the specific roles assigned by the active-tree algorithm. Thus, both proposed algorithms collaborate with each other to automate the self-organizing process for WSNs. The numerical and simulation results demonstrate that the proposed dynamic architecture performs much better than a static architecture in terms of the self-organization of wireless sensor nodes and energy consumption.

• 한국공간구조학회논문집
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• 제7권3호
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• pp.87-95
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• 2007

The recent completions of free-form spatial structures provide us a very attractive form. To realize such an extraordinary shape, it is absolutely necessary that the connector systems have to be investigated the characteristics of the systems and analyzed with a practicable method. In this context, this research consists of not only literature research but also numerical analysis with selected connector systems, which was adopted in real free-form spatial structures. For numerical analysis, especially, finite element analysis (FEA) is performed with a various test parameter using a commercial program ANSYS. Consequently, the general characteristics of node connectors the moment-rotation-curves are presented by considering a large deformation effect as well as a multi-linear material properties.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.768-772
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• 1991

The Self Creating and organizing (SCO) is a new architecture and one of the unsupervized learning algorithm for the artificial neural network. SCO begins with only one output node which has a sufficiently wide response range, and the response ranges of all the nodes decrease with time. Self Creating and Organizing Neural Network (SCONN) decides automatically whether adapting the weights of existing node or creating a new node. It is compared to the Kohonen's Self Organizing Feature Map (SOFM). The results show that SCONN has lots of advantages over other competitive learning architecture.