• 지구물리
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• 제8권3호
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• pp.123-130
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• 2005

It is necessary, in the light of the importance of long-term slope stability problem, to develop a simple method or tool which can figure out the possible failure zone resulted from weathering effect and other factors. The FBG sensor system is used to estimate the correlations between the temperature and the slope in Kimhae, and to find a failure zone in slopes effectively. This research is to seek for the correlation between the soil temperature distribution and the strain distribution in a active zone by analyzing the data from the in-situ measurement so that the possible failure zone should be well defined based on the correlation. For instance, the zone of high temperature fluctuation can be regarded as one of the possible sliding zone due to the weathering effect while the constant temperature depth of the ground, if exists would not be relatively affected by the weathering process.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.614-619
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• 2012

A LQG/LTR(Linear Quadratic Gaussian/Loop Transfer Recovery) controller with an integrator is designed to control the electro-hydraulic positioning system. Without considering the nonlinearity in the dead-zone, computer simulations are performed and show good performances and tracking abilities with the feedback controller based on the linear system model. However, the performance of the closed loop hydraulic positioning system shows big steady-state error in real system because of the dead-zone. In this paper, the feedback controller with a nonlinear compensator is introduced to overcome the dead-zone phenomenon in hydraulic systems. The inverse dead-zone as a nonlinear compensator is used to cancel out the dead-zone phenomenon. Experimental tests are performed to verify the performance of the controller.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.845-850
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• 2007

The empirical AISC panel zone thickness provision$(t_z\geq(d_z+w_z)$/90) to prevent the cyclic shear buckling of the panel zone was proposed based on the test data of Krawinkler et al. (1971) and Bertero et al. (1973) However, no published records of the equation development or any other background information appear to be available. The calibrated finite element analysis results of this study indicated that the AISC provision was not reasonable. In this study, through including the effects of the column axial force and the aspect ratio of the panel zone, a new equation for the relative strength between the beam and the panel zone was proposed such that the proposed equation can prevent the panel zone shear buckling and reduce the potential fracture associated with the kinking of the column flanges.

• 한국실내디자인학회논문집
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• 제25권5호
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• pp.140-147
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• 2016

This research aims to establish the size standard of university library's user space, and present the standard and method to calculate total area required in the planning of new building construction and remodeling. Nine university libraries newly constructed or remodeled since 2000 were selected among the libraries of large scale universities with more than 10,000 enrolled students as the target libraries in this research. The target libraries were classified into A group (five cases partially remodeled) and B group (four cases newly constructed or fully remodeled) on the basis of the change of times. A university library can be divided into three spaces (user space, administration space and public space). This research classified the reading room in the user space into bookshelf zone, reading zone, information/office zone and hall/other zone, and analyzed area ratio according to each zone. B group's bookshelf zone decreased 12% more than A group, and B group's reading zone increased 10% more than A group. However, there was no big change in the area ratio of information/office zone and hall/other zone. This can be interpreted that university library changes from book and archive preservation-oriented space to user-oriented space. This research presented a proper reading room area calculation method, based on the capacity of books, by reflecting such a change. Each zone's standard was set up through classification of domestic and international standards, based on which, the calculation method of university library's total floor area required was presented. The reason why there was difference in university library's total floor area required according to domestic standard and international standard was that the number of enrolled students per seat in the reading room was different. The area calculation methods presented in this research can be utilized as useful data upon planning university library construction or remodeling.

• 한국철도학회논문집
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• 제19권5호
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• pp.585-591
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• 2016

최근 IoT환경에서 다양한 위치기반의 서비스의 확산으로 인해 실내측위는 중요한 영역으로 자리잡고 있다. 이에 본 논문에서는 특정 공간에 시설물, 서비스 등을 고려한 가상의 영역을 Zone으로 설정하였고, 다층퍼셉트론(MLP: Multi-Layer Perceptron)을 사용하여 Zone을 인식하는 방법을 제안하였다. 제안방법의 다층퍼셉트론은 입력으로 BLE(Bluetooth Low Energy) Beacon의 RSSI(Received Signal Strength Indicator)신호를 입력으로 활용하였고 현재 위치의 소속된 Zone을 출력하였다. 제안방법의 검증을 위해서 실제 역사와 유사한 크기의 실험환경을 구축하였으며 4개의 Beacon을 설치하였고 2개의 Zone영역을 설정하였다.

• Journal of Electrical Engineering and Technology
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• 제3권2호
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• pp.192-198
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• 2008

This paper proposes a FRTU-based intelligent fault distance determination strategy in which each FRTU is able to avoid multiple estimations and reduce the level of estimation error by utilizing heuristic rules driven by voltage and current information collected by 1:1 communication with other FRTUs from the same zone in a ubiquitous-based distribution system. In the proposed method, each FRTU, at first, determines a fault zone and a fault path on the faulted zone based on the proposed heuristic rules which use its current data and the voltage data of its neighboring FRTUs as input data. Next, it determines the fault distance from its position based on the fault current estimated from the current data of the neighboring FRTUs. Finally, in order to prove the effectiveness of the proposed method, the diverse fault cases are simulated in several positions of the typical distribution system using the EMTP.

• 디지털콘텐츠학회 논문지
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• 제16권3호
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• pp.407-415
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• 2015

오프라인 English Zone이란 교실 내에서 학습자가 영어로 말하고 듣고, 알고 싶은 단어나 내용을 스스로 찾고 연습하고 그 결과를 확인할 수 있도록 만든 물리적 환경을 말한다. 그러나 제한적이고 인위적 환경에 의존할 수밖에 없는 오프라인의 English Zone은 쇼핑 존, 레스토랑 존, 병원 존 등의 소규모 영어 마을처럼 인위적인 공간을 설정하여 학생들이 자발적으로 Role Play를 체험할 수 있는 환경을 제공해야 하는 극히 제한적인 운영이 될 수밖에 없다. 본 연구의 목적은 이러한 오프라인에서의 English Zone 프로그램을 활용한 학습방법이 가지고 있는 환경적인 제한성의 문제점을 분석하고 유비쿼터스 개념에 기초하여 멀티미디어 도구 활용, 무선 인터넷 활용과 SNS를 활용한 온라인 English Zone 프로그램의 활용 방안을 제시하고자 한다.

• ETRI Journal
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• 제42권5호
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• pp.712-720
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• 2020

Recently, to make the best use of limited and precious spectrum resources, spectrum sharing between satellite and cellular networks has received much interest. In this study, we mathematically analyze the success probability of a fixed (satellite) earth station (FES) based on a stochastic geometry framework. Both the FES and base stations (BSs) are assumed to be equipped with a directional antenna, and the location and the number of BSs are modeled based on the Poisson point process. Furthermore, an exclusion zone is considered, in which the BSs are prohibited from locating in a circular zone with a certain radius around the FES to protect it from severe interference from the cellular BSs. We validate the analytical results on the success probability of the cognitive satellite-terrestrial network with directional antennas by comparing it using extensive computer simulations and show the effect of the exclusion zone on the success probability at the FES. It is shown that the exclusion zone-based interference mitigation technique significantly improves the success probability as the exclusion zone increases.

• Current Optics and Photonics
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• 제7권3호
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• pp.254-262
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• 2023

Novel thermo-optically focus-switchable Fresnel zone plates based on phase-change metafilms are designed and analyzed at a visible wavelength (660 nm). By virtue of the large thermo-optic response of vanadium dioxide (VO₂) thin film, a phase-change material, four different plasmonic phase-change absorbers are numerically designed as actively tunable Gires-Tournois Al-VO₂ metafilms in two and three dimensions. The designed phase-change metafilm unit cells are used as the building blocks of actively focus-switchable Fresnel zone plates with strong focus switching contrast (40%, 83%) and high numerical apertures (1.52, 1.70). The Fresnel zone plates designed in two and three dimensions work as cylindrical and spherical lenses in reflection type, respectively. The coupling between the thermo-optic effect of VO₂ and localized plasmonic resonances in the Al nanostructures offer a large degree of freedom in design and high-contrast focus-switching performance based on largely tunable absorption resonances. The proposed method may have great potential in photothermal and electrothermal active optical devices for nonlinear optics, microscopy, 3D scanning, optical trapping, and holographic displays over a wide spectral range including the visible and infrared regimes.

• Computers and Concrete
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• 제33권5호
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• pp.621-630
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• 2024

This study presents novel electromagnetic wave-based methods for evaluating the integrity of cement-based structures using time domain reflectometry (TDR). Two cement-based plates with embedded rebars are prepared under sound and defective conditions. TDR tests are carried out using transmission lines with various numbers of artificial joints, and electromagnetic waves are measured to assess the integrity of the plates. The experimental results show that the travel time of electromagnetic waves is consistently longer in sound plates than in defective ones, and an increase in the reflection coefficients is observed in the defect zone of the defective plates. Electromagnetic wave velocities are higher in the defective plates, especially when connectors are present in the transmission line. A novel approach based on the area of the reflection coefficient provides larger areas in the defective plates, and the attenuation effect of the electromagnetic waves induces a difference in the areas of the reflection coefficient between the two defect conditions. An alternative method using the centroid of the defect zone slightly overestimates the location of the defect zone. The length of the defect zone is estimated using the defect ratio and wave velocities of cement, air, and plate. The length of the defect zone can also be calculated using the travel times within the plate, total measured length of the plate, and wave velocities in the cement and air. Therefore, the electromagnetic wave-based methods proposed in this study may be useful for estimating the location and length of defect zones by considering attenuation effects.