• Smart Structures and Systems
• /
• 제4권5호
• /
• pp.667-684
• /
• 2008

Numerous devices exist for reducing or eliminating seismic damage to structures. These include passive dampers, semi-active dampers, and active control devices. The performance of structural systems with these devices has often been evaluated using numerical simulations. Experiments on structural systems with these devices, particularly at large-scale, are lacking. This paper describes a real-time hybrid testing facility that has been developed at the Lehigh University NEES Equipment Site. The facility enables real-time large-scale experiments to be performed on structural systems with rate-dependent devices, thereby permitting a more complete evaluation of the seismic performance of the devices and their effectiveness in seismic hazard reduction. The hardware and integrated control architecture for hybrid testing developed at the facility are presented. An application involving the use of passive elastomeric dampers in a three story moment resisting frame subjected to earthquake ground motions is presented. The experiment focused on a test structure consisting of the damper and diagonal bracing, which was coupled to a nonlinear analytical model of the remaining part of the structure (i.e., the moment resisting frame). A tracking indictor is used to track the actuator ability to achieve the command displacement during a test, enabling the quality of the test results to be assessed. An extension of the testbed to the real-time hybrid testing of smart structures with semi-active dampers is described.

• Smart Structures and Systems
• /
• 제4권6호
• /
• pp.809-828
• /
• 2008

Real-time hybrid testing is an attractive method to evaluate the response of structures under earthquake loads. The method is a variation of the pseudodynamic testing technique in which the experiment is executed in real time, thus allowing investigation of structural systems with time-dependent components. Real-time hybrid testing is challenging because it requires performance of all calculations, application of displacements, and acquisition of measured forces, within a very small increment of time. Furthermore, unless appropriate compensation for time delays and actuator time lag is implemented, stability problems are likely to occur during the experiment. This paper presents an approach for real-time hybrid testing in which time delay/lag compensation is implemented using model-based response prediction. The efficacy of the proposed strategy is verified by conducting substructure real-time hybrid testing of a steel frame under earthquake loads. For the initial set of experiments, a specimen with linear-elastic behavior is used. Experimental results agree well with the analytical solution and show that the proposed approach and testing system are capable of achieving a time-scale expansion factor of one (i.e., real time). Additionally, the proposed method allows accurate testing of structures with larger frequencies than when using conventional time delay compensation methods, thus extending the capabilities of the real-time hybrid testing technique. The method is then used to test a structure with a rate-dependent energy dissipation device, a magnetorheological damper. Results show good agreement with the predicted responses, demonstrating the effectiveness of the method to test rate-dependent components.

• 한국표면공학회지
• /
• 제55권6호
• /
• pp.383-389
• /
• 2022

Natural(outdoor) and accelerated(artificial) weathering tests were performed to investigate their influence on polycarbonate. The polycarbonate materials were prepared of various formulations divided into three batches, with existing, development materials1, development materials2, containing mixture of UV additives. Weathering tests were carried out as outdoor weathering(Seosan, South Korea) and accelerated weathering(xenon-arc), and the results analysis were evaluated based on yellow-index(YI), scanning electron microscope(SEM/EDS), energy dispersive x-ray spectroscopy(XRD), and gel permeation chromatography(GPC). Among the three materials, processing method development materials1 with UV stabilizer was excellent in weathering. This study can provide basic data for standardization of development and performance evaluation on livestock barn roof.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 추계학술대회 논문집
• /
• pp.301-305
• /
• 2007

The performance of the railway bogie is classified into the stability and the steering performance. Testing for the bogie stability is conducted on the roller rig. But testing for the bogie steering performance on test facility is very difficult, so the testing for the vehicle curving performance is conducted on the real curve track. And it is desirable to test on the full scale test rig, but it caused many problems relating to test costs, test time. To overcome these problems, the small scale test rig is actively used in the field of bogie stability. Thus, in this paper, we have studied the scale track to test the bogie steering performance. For this, we designed the 1/5 scale test track equivalent to radius 200 curve and confirmed the validity of the testing for the bogie steering performance on the scale curve track through the testing using 1/5 scale bogie.

• Membrane and Water Treatment
• /
• 제2권2호
• /
• pp.121-136
• /
• 2011

A bench-scale test has recently been proposed as a predictive tool to minimize the scope of pilot-scale testing or to optimize the operation of full-scale membrane filtration systems. Consequently, a bench-scale testing unit was developed for this purpose and systematically evaluated in this study. This unit was capable of accommodating commercially available, low pressure, hollow fiber (LPHF) membranes with various configurations for testing under conditions comparable to real-world applications. Reproducibility of this unit in assessing membrane fouling and microbial removal efficiency of LPHF membranes was tested and statistically comparable results were obtained. This unit serves as a useful apparatus for academic researchers and utilities to evaluate the performance of LPHF membranes used for water treatment.

• Ecology and Resilient Infrastructure
• /
• 제5권4호
• /
• pp.257-263
• /
• 2018

본 연구는 도시의 열섬을 저감하기 위해 그린인프라시설의 표면온도 저감 성능시험 장비를 개발하고, 대표적인 그린인프라시설 제품을 포함하여 실험을 수행하였다. 기존문헌을 고찰하여 장비를 개발하였으며, 개발된 장비의 특징은 다음과 같다. 표면온도의 측정방법은 비접촉식인 적외선온도센서를 활용하였으며, 시편의 중앙 온도만 측정하는 것이 아닌 모서리 부분 온도를 포함하여 전체적인 평균온도를 측정하도록 개선하였다. 개발된 장비 (GSTM)를 활용하여 대조군인 아스팔트와 그린인프라시설 제품을 비교하여 성능평가를 수행하였다. 그 결과 식생블록이 $18.4^{\circ}C$의 높은 차이를 보이며, 표면온도 저감에 기여하는 것으로 나타났다.

• Smart Structures and Systems
• /
• 제14권6호
• /
• pp.1269-1289
• /
• 2014

With the sub-stepping technique, the numerical analysis in real-time dynamic hybrid testing is split into the response analysis and signal generation tasks. Two target computers that operate in real-time may be assigned to implement these two tasks, respectively, for fully extending the simulation scale of the numerical substructure. In this case, the integration time-step of solving the dynamic response of the numerical substructure can be dozens of times bigger than the sampling time-step of the controller. The time delay between the real and desired feedback forces becomes more striking, which challenges the well-developed delay compensation methods in real-time dynamic hybrid testing. This paper focuses on displacement prediction and force correction for delay compensation in the real-time dynamic hybrid testing with a large integration time-step. A new displacement prediction scheme is proposed based on recently-developed explicit integration algorithms and compared with several commonly-used prediction procedures. The evaluation of its prediction accuracy is carried out theoretically, numerically and experimentally. Results indicate that the accuracy and effectiveness of the proposed prediction method are of significance.

• Journal of the Korean Data and Information Science Society
• /
• 제23권6호
• /
• pp.1299-1308
• /
• 2012

This article deals with the problem of testing the equality of the scale parameters in nonregular Pareto distributions.We propose Bayesian hypothesis testing procedures for the equality of the scale parameters under the noninformative prior. The noninformative prior is usually improper which yields a calibration problem that makes the Bayes factor to be de ned up to a multiplicative constant. So we propose the default Bayesia hypothesis testing procedures based on the fractional Bayes factor and the intrinsic Bayes factors under the reference priors. Simulation study and a real data example are provided.

• Earthquakes and Structures
• /
• 제18권3호
• /
• pp.337-348
• /
• 2020

Experimental testing has been considered as one of the most straightforward approaches to realize the structural behavior for earthquake engineering studies. Recently, novel and advanced experimental techniques, which combine numerical simulation with experimental testing, have been developed and applied to structural testing practically. However, researchers have to take the risk of damaging specimens or facilities during the process of developing and validating new experimental methods. In view of this, a small-scale structural laboratory has been designed and constructed in order to verify the effectiveness of newly developed experimental technique before it is applied to large-scale testing for safety concerns in this paper. Two orthogonal steel reaction walls and one steel T-slotted reaction floor are designed and analyzed. Accordingly, a large variety of experimental setups can be completed by installing servo-hydraulic actuators and fixtures depending on different research purposes. Meanwhile, a state-of-the-art digital controller and multiple real-time computation machines are allocated. The integration of hardware and software interfaces provides the feasibility and flexibility of developing novel experimental methods that used to be difficult to complete in conventional structural laboratories. A simple experimental demonstration is presented which utilizes part of the hardware and software in the small-scale structural laboratory. Finally, experimental layouts of future potential development and application are addressed and discussed, providing the practitioners with valuable reference for experimental earthquake engineering.

• 한국전산구조공학회논문집
• /
• 제21권5호
• /
• pp.465-474
• /
• 2008

실시간 하이브리드 실험법(real-time hybrid testing method)은 구조물의 수치해석부와 실험부 부분구조를 운동방정식으로 통합하여 실시 간으로 동시에 계산과 실험을 수행하는 방법이다 본 연구는 실시간 하이브리드 실험법을 사용하여 수동 및 준능동 MR감쇠기가 설치된 건축구조물의 내진성능을 정량적으로 평가한다. 건물 모델은 실물 크기 5층 건물을 강제진동실험 결과를 통해 식별한 수치모델로 사용하였고, MR감쇠기는 실험적 부분구조르 UTM에 설치되었다. 본 연구에서 수행되는 실시간 하이브리드 실험은 사인파 및 지진파 가진을 통하여 얻은 결과와 전류에 따른 MR감쇠기의 제어력을 이용하여 얻은 Bouc-Wen모델을 사용하여 얻은 해석모델과 일치함으로 그 유효성을 입증하였다. 또한 예비연구로써 구조물의 응답을 최적으로 제어하기 위한 clipped-optimal 제어알고리즘과 modulated homogeneous friction 준능동 제어알고리즘을 MR감쇠기에 적용하였다. 각 전류별 Bouc-Wen모델을 곡선맞춤하여 각각의 Bouc-Wen모델 파라미터를 식별하였으며 그 결과를 준능동 제어알고리즘 수치해석에 적용하였다. 또한 실시간 하이브리드 실험법을 이용한 준능동 제어 실험결과와 해석결과를 비교하여 준능동 제어알고리즘의 성능을 평가함에 있어 실시간 하이브리드 실험이 합리적임을 보여준다.