• Structural Engineering and Mechanics
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• v.62 no.3
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• pp.345-355
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• 2017

The aim of the present study is to develop an elemental approach based on the differential quadrature method for free vibration analysis of cracked thin plate structures. For this purpose, the equations of motion are established using the classical plate theory. The well-known Generalized Differential Quadrature Method (GDQM) is utilized to discretize the governing equations on each computational subdomain or element. In this method, the differential terms of a quantity field at a specific computational point should be expressed in a series form of the related quantity at all other sampling points along the domain. However, the existence of any geometric discontinuity, such as a crack, in a computational domain causes some problems in the calculation of differential terms. In order to resolve this problem, the multi-block or elemental strategy is implemented to divide such geometry into several subdomains. By constructing the appropriate continuity conditions at each interface between adjacent elements and a crack tip, the whole discretized governing equations of the structure can be established. Therefore, the free vibration analysis of a cracked thin plate will be provided via the achieved eigenvalue problem. The obtained results show a good agreement in comparison with those found by finite element method.

• Structural Engineering and Mechanics
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• v.17 no.3_4
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• pp.393-408
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• 2004

There exists a clear need to monitor the performance of civil structures over their operational lives. Current commercial monitoring systems suffer from various technological and economic limitations that prevent their widespread adoption. The wires used to route measurements from system sensors to the centralized data server represent one of the greatest limitations since they are physically vulnerable and expensive from an installation and maintenance standpoint. In lieu of cables, the introduction of low-cost wireless communications is proposed. The result is the design of a prototype wireless sensing unit that can serve as the fundamental building block of wireless modular monitoring systems (WiMMS). An additional feature of the wireless sensing unit is the incorporation of computational power in the form of state-of-art microcontrollers. The prototype unit is validated with a series of laboratory and field tests. The Alamosa Canyon Bridge is employed to serve as a full-scale benchmark structure to validate the performance of the wireless sensing unit in the field. A traditional cable-based monitoring system is installed in parallel with the wireless sensing units for performance comparison.

• Journal of Korea Multimedia Society
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• v.18 no.10
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• pp.1197-1204
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• 2015

Smoke detection plays an important role for the early detection of fire. In this paper, we suggest a newly developed method that generated LBPV(Local Binary Pattern Variance)s as special feature vectors from RGB contrast images can be applied to detect smoke using SVM(Support Vector Machine). The proposed method rearranges mean value of the block from each R, G, B channel and its intensity of the mean value. Additionally, it generates RGB contrast image which indicates each RGB channel’s contrast via smoke’s achromatic color. Uniform LBPV, Rotation-Invariance LBPV, Rotation-Invariance Uniform LBPV are applied to RGB Contrast images so that it could generate feature vector from the form of LBP. It helps to distinguish between smoke and non smoke area through SVM. Experimental results show that true positive detection rate is similar but false positive detection rate has been improved, although the proposed method reduced numbers of feature vector in half comparing with the existing method with LBP and LBPV.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.553-554
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• 2018

Supply Chain Management (SCM) is the overall process (component procurement, production planning, delivery, inventory control, etc.). It is the process from the supplier to the consumer until the raw material becomes the finished product. Basically, traditional supply chain management is primarily aimed at cost reduction and efficiency. However, considering only cost reduction and efficiency, it is not easy apply the center of 4th industry to Smart Factory. In this study, I propose a form of supply chain management network. It can be satisfy the security by using block chain and automatic control of each element by adding the internet of things.

• Journal of Communications and Networks
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• v.12 no.4
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• pp.334-345
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• 2010

In this paper, we study optimal tradeoffs of achievable throughput versus consumed power in wireless ad-hoc networks formed by a collection of multiple antenna nodes. Relying on adaptive modulation and/or dynamic channel coding rate allocation techniques for multiple antenna systems, we examine the maximization of throughput under power constraints as well as the minimization of transmission power under throughput constraints. In our examination, we also consider the impacts of enforcing quality of service requirements expressed in the form of channel coding block loss constraints. In order to properly model temporally correlated loss observed in fading wireless channels, we propose the use of finite-state Markov chains. Details of fading statistics of signal-to-interference-noise ratio, an important indicator of transmission quality, are presented. Further, we objectively inspect complexity versus accuracy tradeoff of solving our proposed optimization problems at a global as oppose to a local topology level. Our numerical simulations profile and compare the performance of a variety of scenarios for a number of sample network topologies.

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.333-340
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• 1996

We have implemented a planar integrated optics for the fractional Fourier transform (FRT) which has recently been developed as a generalized form of the conventional Fourier transform. FRT optical systems provide versatile tools for analyzing signals and designing hardwares, but require high accuracy and stability in the arrangement of optical components because of their shift-variant characteristic. The planar optical FRT setup composed of free-space optical components integrated on a single glass block makes the FRT of 2-dimensional(2-D) input patterns through the 3-D glass-space. Therefore, taking advantage of the compactness, easy alignment and thermal/mechanical stability, the planar optics can provide a useful approach to realizing an optical fractional correlation system in a practical way. In the experiment, we have obtained accurate FRT results by using the planar integrated optics with 4 different fractional orders of 0.25, 0.5, 0.75, and 1.0.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3743-3748
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• 2013

A tetradentate ligand of 2-phenyl-4,6-di(pyridin-2-yl)pyrimidine (L) has been synthesized and its complexes with $ZnI_2$ and CuI have been obtained by hydrothermal method. single crystal X-ray diffraction analysis indicates that ligand L coordinates with Zn(II) ions to form a simple four-coordinate di-nuclear complex, while the complexation of L with Cu(I) constructs a one-dimensional chain polymer. The existence of $I^-$ ion hampers the L to assemble grid-type complexes with Zn(II) and Cu(I). Fluorescence spectra show that the L emits blue fluorescence while its Cu(I) polymer decrease the fluorescence intensity and Zn(II) complex quenches the fluorescence.

• Structural Engineering and Mechanics
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• v.5 no.4
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• pp.339-353
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• 1997

Fiber reinforced plastic (FRP) rods provide certain benefits over steel as concrete reinforcement, such as corrosion resistance, magnetic and electrical insulation, light weight, and high strength. FRP composites can be combined with a steel core to form hybrid reinforcing rods that take advantage of properties of both materials. The objective of this study was to characterize the bond behavior of hybrid FRP rods made with braided epoxy-impregnated aramid or poly-vinyl alcohol FRP skins. Eleven rod types were tested using two concrete strengths. Specific topics examined were bond strength, slip, and type of failure in concentric pull-out tests from concrete cubes. From analysis of identical pull-out tests on both hybrid and steel rods, information on relative bond strength and behavior were obtained. It is concluded that strength is similar but slip in hybrid rods is much higher. Hybrid rods failed either by pull-out or splitting the concrete block (with or without yielding of the steel core). Experimental data showed consistency with similar test results presented in the literature.

• Journal of the Korean housing association
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• v.17 no.3
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• pp.111-121
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• 2006

The objective of the study is to derive the quantitative result and method from the solar simulation on the traditional architectonic control methods and their effects for the sunshine on Ddeuljip in Northern Area of Kyongsang-Bukdo Province, Korea. The Ddeuljip(rectangular-shaped housing plan having an inner court) has distinctive form to introduce plentiful sunshine deep inside to the house in spite of disadvantageous condition resulted from the structure of traditional housing composition, that is, Ickrang(linkage block connecting buildings). From the research on the Ddeuljip, following results were derived: First, in the plan the sunshine environment was improved by placing the master bedroom on the right diagonally, or projecting it toward the Ickrang when there isn't enough space for the inner court and the Daechung(wooden floored main hall). Second in the elevation specific sunshine control methods were developed by increasing the height of the master bedroom, reducing the eaves of south elevation, or differentiating the height of ceiling structure gradually.

• Aerospace Engineering and Technology
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• v.8 no.1
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• pp.179-186
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• 2009

This paper describes the design and implementation for spread spectrum FTS encoder and decoder. The FTS command format is defined by 64 bit encrypted packet that contains all required information relayed between the ground and the vehicle. Encryption is accomplished using the Tripple-DES encryption algorithm in block encryption form. The proposed FTS encoder and decoder is using the Convolution Encoding and Viterbi Decoding for forward error correction. The Spread Spectrum Modulation is done using a PN code, which is 256 bit gold code. The simulation result shows that the designed FTS decoder is compatible with the designed FTS encoder.