• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.3
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• pp.251-258
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• 2004

Since the multiscale wavelet-based numerical methods allow effective adaptive analysis, they have become new analysis tools. However, the main applications of these methods have been mainly on elliptic problems, they are rarely used for eigenvalue analysis. The objective of this paper is to develop a new multiscale wavelet-based adaptive Galerkin method for eigenvalue analysis. To this end, we employ the hat interpolation wavelets as the basis functions of the finite-dimensional trial function space and formulate a multiresolution analysis approach using the multiscale wavelet-Galerkin method. It is then shown that this multiresolution formulation makes iterative eigensolvers very efficient. The intrinsic difference-checking nature of wavelets is shown to play a critical role in the adaptive analysis. The effectiveness of the present approach will be examined in terms of the total numbers of required nodes and CPU times.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1291-1296
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• 2003

The objective of the present research is to develop a wavelet-based multiscale adaptive Galerkin method for membrane eigenvalue analysis. Since approximate eigensolutions at a certain resolution level can be good guesses, which play an important role in typical iterative solvers, at the next resolution level, the multiresolution iterative solution approach by wavelets can improve the solutionconvergence rate substantially. The intrinsic difference checking nature of wavelets can be also utilized effectively to develop an adaptive strategy. The present wavelet-based approach will be implemented for the simplest vector iteration method, but some important aspects, such as convergence speedup, and the reduction in the number of nodes can be clearly demonstrated.

• Electronics and Telecommunications Trends
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• v.22 no.3 s.105
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• pp.38-45
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• 2007

최근 각광을 받고 있는 RFID 기술은 기존의 바코드를 대체하여 상품 관리를 네트워크화 및 지능화 함으로써 유통 및 물품 관리뿐만 아니라 보안, 안전, 환경 관리 등에 혁신을 선도할 것으로 전망되며, 이전에 존재하지 않았던 거대한 새로운 시장을 형성할 것으로 기대된다. 이러한 RFID 기술은 사물의 고유한 ID를 단순히 인식하는 읽는 기능중심에서 사물의 이력 정보를 관리할 수 있는 읽고 쓰기 기능, 그리고 전자 태그들이 자신의 고유 정보뿐만 아니라 온도, 습도, 압력 등 주변의 정보까지 감지하는 센싱 기능을 가지도록 발전할 것이다. 이와 같이 기존의 ID 획득만 가능한 태그에 외부 환경 정보를 습득할 수 있는 센서와 자체 전원 공급을 위한 박형 전지(film battery)가 추가된RFID 태그를 ‘센서 태그(smart active label 혹은 RFID sensor tag)’라고 부르며, 그방식은 크게 반능동형 방식(semi-passive 혹은 semi-active)과 능동형 방식(active)으로 구분된다. 본 고에서는 현재 국내외에서 활발히 연구 개발되고 있는 반능동형 센서 태그 기술 동향과 센서 태그 관련 국제 표준화 동향에 대해서 알아본다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1827-1828
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• 2007

임베디드 시스템은 주로 처리된 정보를 관리하는 서버를 가지고 있다. 임베디드 시스템 대부분이 많은 양의 데이터를 적재 할 수 없기 때문에 별도로 처리된 정보들을 관리하는 서버가 필요하다. 이런 서버와 임베디드 시스템을 직접 연결하거나 요즘에는 USN을 이용하여 연결하기도 한다. 이런 임베디드 시스템에 다수의 사용자가 접근하여 제어가 가능하도록 하기 위해서 임베디드 미니 웹서버의 역할이 매우 중요하다. 임베디드 미니 웹서의 사용자 접근에는 여러 방법이 있다. 일반적인 웹서버 방법 중에 하나인 ID와 비밀번호를 이용한 로그인 방법이나 IP주소를 구분하는 방법 등이 있다. 하지만 이런 방법들은 완벽한 사용자의 고유성을 보장 할 수 없다. ID와 비밀번호를 도용할 수 있으며, IP주소를 구분하는 것도 아주 한정적인 사용자 관리에 불과하다. 이런 단점을 좀 더 보완하고자 접근 사용자가 RFID리더를 가지고 자신만의 RFID Tag를 읽힘으로써 사용자의 고유성을 높일 수 있다. RFID를 이용한 임베디드 미니 웹서버를 접근하는 시스템을 설계한다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.2
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• pp.28-37
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• 2000

An almost exact eigenvalue equation for optical fibers with graded-index profile Is derived mathematically based on a combination of the modified Airy functions and the WKB trial solution. By applying proper boundary conditions, a phase shift correction term $\delta$ is found out which improves the inherent error problems of the conventional WKB method. It is shown through computer simulations that results of the derived eigenvalue equation are in excellent agreement with those of the finite-element method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.6
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• pp.65-71
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• 1980

The Sn O2-Si Heterojunction sola cells are Prepared by vacuum deposition of SnO2 on N- and P-type Si - wafers arts the effects of annealing on the Solar cell characteiistics are presented. The existence of optimumannealins temperature for maximum open-circuit voltage and short - circuit current of the solar cell is observed. The optimum tomperature, when low resistivity (7- 2.3 [$\Omega$.cm]) P-and N-type Si -wafers are used, is 500 [$^{\circ}C$] End 400 [$^{\circ}C$] when high resistivity[41-58 [$\Omega$.cm]) P-type Si-wafers are used.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.349-350
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• 2003

멸치, Engraulis japonica는 우리나라 주변해역에 널리 분포하는 소형의 표층성 부어로서 특히 국내 남해에 있어서는 상업적으로 중요한 어획대상종이 되고 있다(장등, 1980). 또한 멸치는 자치어기부터 성어에 이르는 단계까지 어식성 어류들의 주요한 먹이원이 되고 있는데 이는 소형의 플랑크들을 주로 섭이하고 있는 멸치가 해양의 저차생산력을 이용가능한 자원으로 변환시키는 역할을 담당하는 등 천연의 먹이생태계에 있어서도 중대한 위치를 차지하고 있는 어종이라 볼 수 있다(화전, 1997). (중략)

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.251-258
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• 1993

The main purpose of this paper is to present both the natural frequencies and the buckling loads of beam-columns on Winkler-type foundations. The ordinary differential equations governing the free vibrations and the buckling loads of beam-columns on Winkler-type foundation are derived as nondimensional forms. The Runge-Kutta method and Determinant Search method are used to perform the integration of the differential equations and to determine the eigenvalues(natural frequencies and buckling loads), respectively. Hinged-hinged and damped-clamped end constraints are applied in numerical examples. The relation between frequency parameter and elastic foundation parameter is presented in figure. The effects of axial loads on the natural frequencies of beam-columns on elastic foundations are investigated and the relation between buckling load parameter and elastic foundation parameter is also analyzed. The relation between foundation rested ratio and frequency parameter, buckling load parameter are investigated. The beam-columns on non-homogeneous elastic foundation are analyzed and typical mode shapes are also presented.

• Fire Science and Engineering
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• v.17 no.2
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• pp.17-24
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• 2003

Thermal effects and characteristics of heat release for electrical wire installed in pascon and concrete trough have been theoretically approached and studied in consideration of the structure of products. The points of difference between two troughs have been evaluated by theoretical approach and estimated by computer simulation in similar condition of institution environment. As a result, the average of the intrinsic thermal conductivity of concrete trough is superiority to pascon trough considering only for characteristic of materials. But when considering for institution environment (thickness, area and trough structure etc) as the results of the calculation and computer simulation using FLUENT, the degree of heat release for pascon trough is of advantage to concrete trough.

• Journal of Advanced Navigation Technology
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• v.5 no.2
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• pp.111-122
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• 2001

In this paper, we study the performance of eigencanceller which use a eigenvector and eigenvalue in order to update a weighter vector. Eigencanceller can suppress directional interferences and noise effectively while maintaining specified beam pattern constraints. The constraints and optimal weight vector of eigencanceller vary by using interference and noise or desired signal, interference signal and noise as array input signal. From the analysis results in the steady state, We show that weight vectors in each case are simplified the form of projection equation that belongs to desired subspace orthogonal to interference subspace and eigencanceller has the better performance than RLS method through mathematical analysis and simulation.