• 전자통신동향분석
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• 제22권3호통권105호
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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.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.511-518
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• 2006

In this study, seismic response mitigation effect of an MR damper generating response-dependent frictional force is investigated. It has been reported in previous studies that passively operated MR damper with constant input current doesn't show better control performance than semi-active MR damper with varying input current calculated by control algorithms such as linear quadratic regulator and sliding mode control. However, in order to operate the MR damper semi-actively, other control systems besides the damper itself such as sensors for measuring structural responses and controller for calculating optimal input current are necessary, which deteriorate the economical efficiency. This study presents a MR damper generating frictional force of which magnitude is controlled in accordance to the displacement and velocity transferred to the damper. Numerical analyses results indicate that the performance of the response dependent MR damper is closely related with the range of the friction force and it can be designed to short better control performance than the passive MR damper.

• 대한기계학회논문집A
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• 제31권1호
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• pp.129-138
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• 2007

In this paper, a modified sensitivity control for the semi-active suspension system with a magneto-rheological (MR) damper is investigated. A 2-d.o.f quarter-car model together with a 6th order polynomial model for the MR damper is considered. For the purpose of suppressing the vertical acceleration of the sprung mass, the square of the vertical acceleration is defined as a cost function and a modified sensitivity control that updates the current input in the negative gradient of the cost function is proposed. The implementation of the proposed algorithm requires only the measurement of the relative displacement of the suspension deflection. The local stability of equilibria of the closed loop nonlinear system is proved by investigating the eigenvalues of the linearized ones. Through simulations, the passive suspension, the skyhook control, and the proposed modified sensitivity control are compared.

• 한국언어정보학회:학술대회논문집
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• 한국언어정보학회 2005년도 하계 학술대회
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• pp.71-85
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• 2005

To build a Korean wordnet, we translated semi-automatically the English wordnet PWN into Korean verbs. During this process, we found that some of translation errors are related to the arbitrariness of PWN`s sense distinction in regard to the accusativity/inaccusativity of the same verb form in English. This study presents an empirically based method of remodeling the PWN for Korean wordnet and while revising the PWN`s hierarchical structure, it shows the necessity of classifying the Korean passive verbs as semantically autonomous.

• 한국지진공학회논문집
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• 제13권3호
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• pp.39-50
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• 2009

인접건물 사이에 감쇠기 형태의 에너지 소산장치를 설치하고 연결함으로써, 지진 응답을 줄이고 내진 성능을 향상시킬 수 있는 방법에 대하여 연구를 수행하였다. 서로 인접한 건물 간의 진동제어를 위하여 준능동 MR 감쇠기를 이용하는 퍼지 제어기법을 제시하고, MR 감쇠기의 감쇠력 조절을 시간에 따라 제어할 수 있도록 제시한 방법으로 제어기를 설계하였다. 제시한 방법의 타당성을 검증하기 위하여 수치모사를 수행하였으며, 다양한 역사지진의 지진응답 해석을 통해서 비제어시, 수동제어 및 준능동 퍼지제어 등에 대한 최대응답을 비교 분석하였다. 수치모사 결과 제시한 방법은, 다양한 주파수 성분을 가진 여러 가지 지진에 대해 매우 효과적인 제진 성능을 보이는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제70권6호
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• pp.765-779
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• 2019

Most of the existing evaluation criteria of vibration serviceability rely on the peak acceleration of the structure rather than that of the people keeping their own body unmoved on the structure who is the real receiver of structural vibrations. In order to accurately assess the vibration serviceability, therefore, a full path assessment approach of vibration serviceability based on vibration source, path and receiver is not only tentatively proposed in this paper, taking the peak acceleration of receiver into account, but also introduce a probability procedure to provide more instructive information instead of a single value. In fact, semi-rigid supported on both sides of the structure is more consistent with the actual situation than simply supported or clamped due to the application of the prefabricated footbridge structures. So, the footbridge is regarded as a beam with semi-rigid supported on both sides in this paper. The differential quadrature-integral quadrature coupled method is not only to handle different type of boundary conditions, but also after being further modified via the introduction of an approximation procedure in this work, the time-varying system problem caused by human-structure interaction can be solved well. The analytical results of numerical simulations demonstrate that the modified differential quadrature-integral quadrature coupled method has higher reliability and accuracy compared with the mode superposition method. What's more, both of the two different passive control measures, the tuned mass damper and semi-rigid supported, have good performance for reducing vibrations. Most importantly, semi-rigid supported is easier to achieve the objective of reducing vibration compared with tuned mass damper in design stage of structure.

• 한국공간구조학회논문집
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• 제12권1호
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• pp.99-108
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• 2012

본 연구에서는 지진하중을 받는 대공간 구조물의 지진응답을 저감시키기 위하여 돔 구조물에 대한 동조질량제어장치(TMD)의 적용성을 검토하였다. 이를 위하여 돔 구조물의 기본적인 동적특성을 가지고 있으며 가장 간단한 구조이기도 한 스타 돔 구조물에 수동형 TMD를 설치하여 지진응답 제어성능을 평가하였다. 본 연구에서는 KBC2009에 따른 인공 지진하중을 수평방향과 연직방향으로 가하여 스타 돔 구조물에 대한 지진응답을 분석하였으며 이를 바탕으로 TMD의 설치에 따른 스타 돔 구조물의 지진응답 제어성능을 분석하였다. 해석결과 다음과 같은 결론을 얻을 수 있었다. 지진하중의 방향에 반응하는 스타 돔 구조물의 진동모드 분석을 통하여 수동 TMD를 설치하는 것이 지진응답 제어에 있어서 효과적인 것을 확인할 수 있었다.

• Corrosion Science and Technology
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• 제2권2호
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• pp.68-74
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• 2003

The effects of Niobium on the structure and properties(especially electric properties) of passive film of Zirconium alloys in pH 8.5 buffer solution are examined by the photo-electrochemical analysis. For Zr-xNb alloys (x = 0, 0.45, 1.5, 2.5 wt%), photocurrent began to increase at the incident energy of 3.5 ~ 3.7 eV and exhibited the $1^{st}$ peak at 4.3 eV and the $2^{nd}$ peak at 5.7 eV. From $(i_{ph}hv)^{1/2}$ vs. hv plot, indirect band gap energies $E_g{^1}$= 3.01~3.47 eV, $E_g{^2}$= 4.44~4.91 eV were obtained. With increasing Nb content, the relative photocurrent intensity of $1^{st}$ peak significantly increased. Compared with photocurrent spectrum of thermal oxide of Zr-2.5Nb, It was revealed that $1^{st}$ peak in photocurrent spectrum for the passive film formed on Zr-Nb alloy was generated by two types of electron transitions; the one caused by hydrous $ZrO_2$ and the other created by Nb. Two electron transition sources were overlapped over the same range of incident photon energy. In the photocurrent spectrum for passive film formed on Zr-2.5Nb alloy in which Nb is dissolved into matrix by quenching, the relative photocurrent intensity of $1^{st}$ peak increased, which implies that dissolved Nb act as another electron transition source.

• Smart Structures and Systems
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• 제29권3호
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• pp.499-512
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• 2022

This work proposes a novel contactless vibration damping and thermal isolation tripod platform based on Superconducting Magnetic Levitation (SML). This prototype is suitable for cryogenic environments, where classical passive, semi active and active vibration isolation techniques may present tribological problems due to the low temperatures and/or cannot guarantee an enough thermal isolation. The levitating platform consists of a Superconducting Magnetic Levitation (SML) with inherent passive static stabilization. In addition, the use of Operational Modal Analysis (OMA) technique is proposed to characterize the transmissibility function from the baseplate to the platform. The OMA is based on the Stochastic Subspace Identification (SSI) by using the Expectation Maximization (EM) algorithm. This paper contributes to the use of SSI-EM for SML applications by proposing a step-by-step experimental methodology to process the measured data, which are obtained with different unknown excitations: ambient excitation and impulse excitation. Thus, the performance of SSI-EM for SML applications can be improved, providing a good estimation of the natural frequency and damping ratio without any controlled excitation, which is the main obstacle to use an experimental modal analysis in cryogenic environments. The dynamic response of the 510 g levitating platform has been characterized by means of OMA in a cryogenic, 77 K, and high vacuum, 1E-5 mbar, environment. The measured vertical and radial stiffness are 9872.4 N/m and 21329 N/m, respectively, whilst the measured vertical and radial damping values are 0.5278 Nm/s and 0.8938 Nm/s. The first natural frequency in vertical direction has been identified to be 27.39 Hz, whilst a value of 40.26 Hz was identified for the radial direction. The determined damping values for both modes are 0.46% and 0.53%, respectively.

• Structural Engineering and Mechanics
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• 제61권5호
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• pp.675-684
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• 2017

In this paper, a hybrid seismic response control (HSRC) system was developed to control bridge behavior caused by the seismic load. It was aimed at optimum vibration control, composed of a rubber bearing of passive type and MR-damper of semi-active type. Its mathematical modeling was driven and applied to a bridge model so as to prove its validity. The bridge model was built for the experiment, a two-span bridge of 8.3 meters in length with the HSRC system put up on it. Then, inflicting the EI Centro seismic load on it, shaking table tests were carried out to confirm the system's validity. The experiments were conducted under the basic structure state (without an MR-damper applied) first, and then under the state with an MR-damper applied. It was also done under the basic structure state with a reinforced rubber bearing applied, then the passive on/off state of the HSRC system, and finally the semi-active state where the control algorithm was applied to the system. From the experiments, it was observed that pounding rather increased when the MR-damper alone was applied, and also that the application of the HSRC system effectively prevented it from occurring. That is, the experiments showed that the system successfully mitigated structural behavior by 70% against the basic structure state, and, further, when control algorithm is applied for the operation of the MR-damper, relative displacement was found to be effectively mitigated by 80%. As a result, the HSRC system was proven to be effective in mitigating responses of the two-span bridge under seismic load.