• Earthquakes and Structures
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• 제24권6호
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• pp.415-428
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• 2023

Low-cost techniques with seismic isolation performance and excellent resilience need to be explored in the case of rural low-rise buildings because of the limited buying power of rural residents. As an inexpensive and eco-friendly isolation bearing, scrap tire pads (STPs) have the issue of poor resilience. Thus, a seismic isolation system under a column (SISC) integrated with STP needs to be designed for the seismic protection of low-rise rural buildings. The SISC, which is based on a simple exterior design, maintains excellent seismic performance, while the mechanical behavior of the internal STP provides elastic resilience. The horizontal behaviors of the SISC are studied through load tests, and its mechanical properties and the intrinsic mechanism of the reset ability are discussed. Results indicate that the average residual displacement ratio was 24.59%, and the reset capability was enhanced. Comparative experimental and finite element analysis results also show that the load-displacement relationship of the SISC was essentially consistent. The dynamic characteristics of isolated and fixed-base buildings were compared by numerical assessment of the response control effects, and the SISC was found to have great seismic isolation performance. SISC can be used as a low-cost base isolation device for rural buildings in developing countries.

• 한국전자통신학회논문지
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• 제19권4호
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• pp.771-780
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• 2024

본 연구에서는 딸기 농장을 대상으로 YOLOv5 아키텍처를 기반으로 한 컴퓨터 비전 모델과 Isolation Forest Classifier를 적용하여 병충해를 실시간으로 감지 및 예측하는 시스템을 개발하였다. 모델 성능 평가 결과, YOLOv5 모델은 평균 정밀도(mAP 0.5) 78.7%, 정확도 92.8%, 재현율 90.0%, F1 점수 76%로 높은 예측 성능을 나타냈다. 본 시스템은 딸기 농장뿐만 아니라 다른 작물과 다양한 환경에도 적용할 수 있도록 설계되었다. 토마토 농장에서 수집된 데이터를 기반으로 새로운 AI 모델을 학습한 결과, 주요 병충해인 역병과 황화병에 대한 예측 정확도가 85% 이상으로 나타났으며, 기존 모델보다 예측 정확도가 10% 이상 향상되었다.

• 한국지진공학회논문집
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• 제11권2호
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• pp.19-26
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• 2007

본 연구에서는 Coil Spring과 Viscous Damper 시스템의 동특성 분석을 위한 특성실험을 수행하였다. Coil Spring과 Viscous Damper 시스템은 원자력발전소 비상디젤발전기의 진동저감 및 지진력 저감을 위한 장치로 선정되었다. Viscous Damper 가진 속도에 따라서 그 특성이 다르게 나타나기 때문에 그 영향을 평가하여 진동저감과 지진력 저감효과를 동시에 고려할 수 있는 장치로서의 성능을 평가하고자 하는 것이다. 실험결과 수평방향의 경우 속도의존 비선형 거동이 두드러지게 나타나고 있는 반면 연직방향은 그러한 특성이 미미한 것으로 나타났다. 강성과 감쇠 모두 설계값보다 고평가 되고 있는 것으로 나타나서 전체 시스템의 면진 및 진동저감시 영향을 미칠 수 있는 것으로 나타났다.

• 한국전자파학회논문지
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• 제18권8호
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• pp.862-865
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• 2007

RFID 시스템에서는 현재 같은 주파수 대역에서 송신 단과 수신 단이 사용되며, 이에 따라 듀플렉서를 사용할 수 없게 되며 커플러를 사용하게 된다. 커플러를 사용함으로써 송신 누설 신호는 수신 단으로 직접적으로 영향을 주며, 이에 따라 태그의 인식 거리가 제한되는 부정적인 영향을 미치게 된다. 본 논문에서는 Rx 단으로 직접 적으로 영 향을 주는 Tx 누설 신호를 감쇄시키는 방법을 소개하고 ADS2006 시뮬레이션으로 이를 검증하였다

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.15-16
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• 2010

This paper is study on a high efficiency DC-DC converter of discontinuous conduction mode (DCM) added electric isolation. The converters of high efficiency are generally made that the power losses of the used semiconductor switching devices is minimized. To achieve high efficiency system, the proposed converter is constructed by using a quasi resonant circuit. The control switches using in the converter are operated with soft switching by quasi resonant method. The control switches are operated without increasing their voltage and current stresses by the soft switching technology. The result is that the switching loss is very low and the efficiency of the system is high. The proposed converter is also added electric isolation which is used a pulse transformer. When the power conversion system is required electric isolation, the proposed converter is adopted with the converter system development of high efficiency. The soft switching operation and the system efficiency of the proposed converter are verified by digital simulation and experimental results.

• Smart Structures and Systems
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• 제21권3호
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• pp.373-387
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• 2018

Semi-active isolation systems based on leverage-type stiffness control strategies have been widely studied. The main concept behind this type of system is to adjust the stiffness in the isolator to match the fundamental period of the isolated system by using a simple leverage mechanism. Although this system achieves high performance under far-field earthquakes, it is unsuitable for near-fault strong ground motion. To overcome this problem, this study considers the potential energy effect in the control law of the semi-active isolation system. The minimal energy weighting (MEW) between the potential energy and kinetic energy was first optimized through a series of numerical simulations. Two MEW algorithms, namely generic and near-fault MEW control, were then developed to efficiently reduce the structural displacement responses. To demonstrate the performance of the proposed method, a two-degree-of-freedom structure was employed as a benchmark. Numerical results indicate that the dynamic response of the structure can be effectively dampened by the proposed MEW control under both far-field and near-fault earthquakes, whereas the structural responses resulting from conventional control methods may be greater than those for the purely passive control method. Moreover, according to experimental verifications, both the generic and near-fault MEW control modes yielded promising results under impulse-like earthquakes. The practicability of the proposed control algorithm was verified.

• 한국지진공학회논문집
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• 제8권5호통권39호
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• pp.65-77
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• 2004

본 연구에서는 원전기기의 내진안전성을 향상시키기 위한 진동대 실험을 수행하였다. 원전 격납건물과 유사한 진동수 특성을 가지는 구조물을 제작하여 실험에 사용하였으며 구조물 내부에 설치된 기기를 모사 하기 위하여 면진장치가 설치된 강체블럭을 층바닥에 설치하였다. 주파수 특성이 상이한 3종류의 지진파를 이용하여 진동대 실험을 수행하였다. 면진장치로는 천연고무베어링(NRB)과 고감쇠고무베어링(HDRB)을 사용하여 고무의 감쇠특성에 따른 면진기기의 효율성을 분석하였다. 또한 입력지진동의 주파수 특성에 따라 적절한 면진장치의 기기면진효과를 평가하였다. 실험결과 적절한 면진장치를 사용함으로써 기기의 지진응답을 크게 줄일 수 있으며 지진에 대한 안전성을 향상키킬 수 있는 것으로 나타났다.

• Smart Structures and Systems
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• 제16권4호
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• pp.701-723
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• 2015

Friction isolators are one of the most important types of bearings used to mitigate damages of earthquakes. The adaptive behavior of these isolators allows them to achieve multiple levels of performances and predictable seismic behavior during different earthquake hazard levels. There are three main types of friction isolators. The first generation with one sliding surface is known as Friction Pendulum System (FPS) isolators. The double concave friction pendulum (DCFP) with two sliding surfaces is an advanced form of FPS, and the third one, with fully adaptive behavior, is named as triple concave friction pendulum (TCFP). The current study has been conducted to investigate and compare seismic responses of these three types of isolators. The structure is idealized as a two-dimensional single degree of freedom (SDOF) resting on isolators. The coupled differential equations of motion are derived and solved using state space formulation. Seismic responses of isolated structures using each one of these isolators are investigated under seven near fault earthquake motions. The peak values of bearing displacement and base shear are studied employing the variation of essential parameters such as superstructure period, effective isolation period and effective damping of isolator. The results demonstrate a more efficient seismic behavior of TCFP isolator comparing to the other types of isolators. This efficiency depends on the selected effective isolation period as well as effective isolation damping. The investigation shows that increasing the effective isolation period or decreasing the effective isolation damping improves the seismic behavior of TCFP compared to the other isolators. The maximum difference in seismic responses, the base shear and the bearing displacement, for the TCFP isolator are calculated 26.8 and 13.4 percent less than the DCFP and FPS in effective isolation damping equal to10%, respectively.

• 한국공간구조학회논문집
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• 제8권6호
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• pp.49-57
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• 2008

지진에 의한 구조물의 응답을 저감시키기 위하여 다양한 면진장치가 사용되고 있으며 면진장치가 설치된 구조물은 고유주기가 길어져서 지진파의 탁월 주기를 벗어나게 된다. 대공간 구조물의 상부(지붕)구조인 트러스 아치는 하부구조인 기둥에 의하여 지지되는 경우가 있을 수 있다. 본 연구에서는 하부 기둥에 따른 면진 트러스 아치구조물의 거동을 분석하고자 한다. 면진장치를 대공간 구조물에 적용할 경우에 수평지진하중에 의하여 수평방향 지진응답이 저감되는 것은 물론 면진장치의 수직강성으로 인하여 수직응답도 현저하게 저감되는 것을 알 수 있었다. 하부의 기둥 강성이 큰 경우에 트러스 아치의 거동은 기둥 없이 트러스 아치가 지반에 직접 지지되는 트러스 아치의 거동과 유사하게 나타나고 있다. 또한 하부구조의 강성이 비교적 작은 대공간구조물에 면진장치를 적용할 경우에는 지진응답에 대한 우수한 제어 성능을 얻을 수 있을 것이다.

• Earthquakes and Structures
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• 제9권3호
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• pp.603-623
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• 2015

The scale and nature of the recent earthquakes in the world and the related earthquake disaster index coerce the concerned community to become anxious about it. Therefore, it is crucial that seismic lateral load effect will be appropriately considered in structural design. Application of seismic isolation system stands as a consistent alternative against this hazard. The objective of the study is to evaluate the structural and economic feasibility of reinforced concrete (RC) buildings with base isolation located in medium risk seismic region. Linear and nonlinear dynamic analyses as well as linear static analysis under site-specific bi-directional seismic excitation have been carried out for both fixed based (FB) and base isolated (BI) buildings in the present study. The superstructure and base of buildings are modeled in a 3D finite element model by consistent mass approach having six degrees of freedom at each node. The floor slabs are simulated as rigid diaphragms. Lead rubber bearing (LRB) and High damping rubber bearing (HDRB) are used as isolation device. Change of structural behaviors and savings in construction costing are evaluated. The study shows that for low to medium rise buildings, isolators can reduce muscular amount of base shears, base moments and floor accelerations for building at soft to medium stiff soil. Allowable higher horizontal displacement induces structural flexibility. Though incorporating isolator increases the outlay, overall structural cost may be reduced. The application of base isolation system confirms a potential to be used as a viable solution in economic building design.