• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.3
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• pp.185-191
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• 2007

For the seismic performance enhancement of residential flat plate structure and for the selection of earthquake records, the possibility of base isolation is evaluated and the time history results are reviewed. By evaluating a base isolated stiffness, a target period, and an envelope curve analysis, seismic performance of structure, which has strong rotational mode, is evaluated. For the propriety evaluation of earthquake records usage and scaling method, time history analysis is done with variables such as DBE(design base earthquake) level, MCE(maximum considerable earthquake) level, and 1.4DBE level. From the analysis results, following conclusions can be made; the earthquake records, which are used in base isolation analysis, should be selected by similar soil type which the structure is considered, and should be intensity scaled in a range of mean ${\pm}$ standard deviation of code based design response spectrum.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.4
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• pp.15-23
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• 2009

An experimental study was performed to evaluate seismic reduction performance and the applicability of 2-dimensional floor isolation system to the main control room of a nuclear power plant. A lead-rubber bearing (LRB) and a friction pendulum system (FPS) were designed and fabricated for a 2-dimensional floor isolation system. A partial experimental model of a main control room with the LRB and FPS was tested using a shaking table. The experimental model consisted of a control panel, a 2.5m${\times}$2.5m access floor, and four LRB and FPS. The artificial time histories based on the horizontal floor response spectrums (OBE, SSE) of the main control room were used as earthquake input signals. Compared to the non-isolated system, the seismic response of experimental models using a 2-dimensional floor isolation system showed considerable seismic reduction performance against an earthquake.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.1
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• pp.57-66
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• 2008

An experimental study was performed to evaluate seismic reduction performance and applicability of 3-dimensional floor isolation system to the main control room of nuclear power plant. A friction pendulum system(FPS) and air spring were designed and fabricated for 3-dimensional floor isolation system. Two kind of the partial experimental model of a main control room attached to the FPS and air spring were tested on the shaking table. The experimental model consisted of a control panel, a $2.5m{\times}2.5m$ access floor, four FPS and air springs. The artificial time histories based on the vertical and horizontal floor response spectrums(OBE, SSE) of the main control room were used as the earthquake input signals in the test. Compared to non-isolated system, the seismic response of experimental models using 3-dimensional floor isolation system were shown considerable seismic reduction performance.

• Smart Structures and Systems
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• v.23 no.1
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• pp.91-106
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• 2019

Adopting sloped rolling-type isolation devices underneath a raised floor system has been proved as one of the most effective approaches to mitigate seismic responses of the protected equipment installed above. However, pounding against surrounding walls or other obstructions may occur if such a base-isolated raised floor system is subjected to long-period excitation, leading to adverse effects or even more severe damage. In this study, real-time hybrid simulation (RTHS) is adopted to assess the control performance of a smart base-isolated raised floor system as it is an efficient and cost-effective experimental method. It is composed of multiple sloped rolling-type isolation devices, a rigid steel platen, four magnetorheological (MR) dampers, and protected high-tech equipment. One of the MR dampers is physically tested in the laboratory while the remainders are numerically simulated. In order to consider the effect of input excitation characteristics on the isolation performance, the smart base-isolated raised floor system is assumed to be located at the roof of a building and the ground level. Four control algorithms are designed for the MR dampers including passive-on, switching, modified switching, and fuzzy logic control. Six artificial spectrum-compatible input excitations and three slope angles of the isolation devices are considered in the RTHS. Experimental results demonstrate that the incorporation of semi-active control into a base-isolated raised floor system is effective and feasible in practice for high-tech industry.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.2
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• pp.35-42
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• 2022

In this paper, a method to increase the combining efficiency and isolation of the combiner, the core module of SSPA (solid state amplifier), was studied. Specifically, the isolation was secured by matching the common port and the isolation port in the waveguide combiner. The matching structure for matching is in the form of a circular disk and is engraved inside the waveguide combiner. The structure is very simple, so it is possible to secure stable performance. And this structure showed more than 60 times higher critical power performance compared to previous studies, confirming that it is suitable for high output. And by combining 1-stage T-junction and 2, 3 stage MagicT combiner, miniaturization was achieved and the combining efficiency was optimized by reducing the insertion loss. The fabricated waveguide coupler obtained an isolation of 16dB or more and a coupling efficiency of 86.2%.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.4
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• pp.771-780
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• 2024

In this study, we implemented a real-time pest detection and prediction system for a strawberry farm using a computer vision model based on the YOLOv5 architecture and an Isolation Forest Classifier. The model performance evaluation showed that the YOLOv5 model achieved a mean average precision (mAP 0.5) of 78.7%, an accuracy of 92.8%, a recall of 90.0%, and an F1-score of 76%, indicating high predictive performance. This system was designed to be applicable not only to strawberry farms but also to other crops and various environments. Based on data collected from a tomato farm, a new AI model was trained, resulting in a prediction accuracy of over 85% for major diseases such as late blight and yellow leaf curl virus. Compared to the previous model, this represented an improvement of more than 10% in prediction accuracy.

• Journal of Korean Association for Spatial Structures
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• v.8 no.5
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• pp.75-82
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• 2008

In this study, the possibility of vibration control of high-rise building structures by applying top-story isolation has been investigated. To this end, El Centro NS (1940) earthquake load is applied to 20- and 50-story building structures for numerical analysis. Artificial wind loads are used to evaluate the serviceability of example structures against wind vibration. As the number of isolated stories of example buildings is changed, structural responses has been evaluated to investigate optimal isolated building mass. And the natural period of isolation systems for top-story isolation is varied to investigate the improvement of control performance compared with the fixed base structure. Based on the analytical results, the top-story isolation system can be used as a hued mass damper and effectively reduce the structural responses of high-rise buildings against wind and seismic loads.

• Journal of information and communication convergence engineering
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• v.9 no.6
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• pp.647-651
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• 2011

In this letter, non-regenerative Amplify-and-Forward (AF) relay systems based on half and full duplex schemes are investigated and their performance is analyzed and compared in terms of outage probability. Although the AF relay systems have been widely investigated in many previous literatures, most of them adopted a half duplex scheme due to hardware limitation and mathematical tractability. To the best of our knowledge, this letter is the first study to investigate the performance of the full duplex AF relay system considering practical hardware limitations. In full duplex AF relay systems, it is important to secure the isolation between transmit and receive antennas. Our numerical and simulation results show that there exists a threshold point of the isolation gain that the full duplex relay system outperforms the half duplex relay system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.1
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• pp.56-65
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• 2011

A new hybrid mount system is proposed for microvibration control in a high-tech factory. The mount consists of an airspring as a passive device and a piezostack actuator as an active device. The two devices are connected in series. Some numerical simulations and experimental tests are carried out to evaluate isolation performance of the mount system comprising of four proposed hybrid mounts. As a control logic, the specific algorithm is adopted for considering multiple target frequencies of excitation based on a Filtered-X LMS algorithm. The results are compared with isolation performance of the passive airspring mount system. It is confirmed that the proposed hybrid mount system has great performance on microvibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.380-383
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• 2006

This study examines the influence factor of flanking transmission in the wall. Generally, there is the difference of airborne sound isolation between laboratory and field test. The purpose of this study is examing the cause of droping sound insulation performance in the field and searching the method of improving sound insulation performance. First, we measured the sound isolation in the wall at the lab. Then, we measured it in the field and compared them. At the base of these datum, we measured the flanking transmission and solid transmission. For the flanking transmission am the wall, we used intensive method. So, we found the influence of solid transmission.