• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.1
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• pp.9-19
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• 2016

Permanent deformation plays a key role in performance based earthquake resistant design. In order to estimate permanent deformation after earthquake, it is essential to secure reliable response history analysis(RHA) as well as earthquake scenario. This study focuses on permanent deformation of an inverted T-type wall under earthquake. The study is composed of two separate parts. The first one is on the verification of RHA and the second one is on an effect of input earthquake motion. The former is discussed in companion paper and the latter in this paper. In order to investigate the effect of an input earthquake motion on the permanent deformation, three bins of spectral matched real earthquake records with different magnitude, regions, epicentral distance are constructed. Parametric study was performed using the verified RHA through the companion paper for each earthquake records in the bins. The most influential parameter affecting permanent displacement is magnitude. The other parameters describing earthquake motion are not significant enough to increase permanent displacement of the inverted T-type wall except for energy related parameters(AI, CI, SEI).

• Geomechanics and Engineering
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• v.9 no.1
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• pp.39-55
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• 2015

Usually the analyses of structures are carried out by assuming the base of structures to be fixed. However, the soil beneath foundation alters the earthquake loading and varies the response of structure. Hence, it is not realistic to analyze structures by considering it to be fixed. The importance of soil-structure interaction was realized from the past failures of massive structures by neglecting the effect of soil in seismic analysis. The analysis of massive structures requires soil flexibility to be considered to avoid failure and ensure safety. Present study, considers the seismic behavior of multi-storey reinforced concrete narrow and wide buildings of various heights with and without shear wall supported on raft foundation incorporating the effect of soil flexibility. Analysis of the three dimensional models of six different shear wall positions founded on four different soils has been carried out using finite element software LS DYNA. The study investigates the differences in spectral acceleration coefficient (Sa/g), base shear and storey shear obtained following the seismic provisions of Indian standard code IS: 1893 (2002) (IS) and International building code IBC: 2012 (IBC). The base shear values obtained as per IBC provisions are higher than IS values.

• Wind and Structures
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• v.18 no.1
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• pp.37-56
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• 2014

The evaluation of pressure fields acting on slender structures under wind loads is currently performed in experimental aerodynamic tests. For wind-sensitive structures, in fact, the knowledge of global and local wind actions is crucial for design purpose. This paper considers a particular slender structure under wind excitation, representative of most common high-rise buildings, whose experimental wind field on in-scale model was measured in the CRIACIV boundary-layer wind tunnel (University of Florence) for several angles of attack of the wind. It is shown that an efficient reduced model to represent structural response can be obtained by coupling the classical structural modal projection with the so called blowing modes projection, obtained by decomposing the covariance or power spectral density (PSD) wind tensors. In particular, the elaboration of experimental data shows that the first few blowing modes can effectively represent the wind-field when eigenvectors of the PSD tensor are used, while a significantly larger number of blowing modes is required when the covariance wind tensor is used to decompose the wind field.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.86-91
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• 2009

In this paper, we analyze the Transition of Isc by natural solar spectrum of c-Si and a-Si PV module. Commonly, performance of photovoltaic (PV) module is estimated under the standard test condition (STC). That is, solar irradiance $1kW/m^2$, solar spectrum distribution: AM1 5G, module temperature $25^{\circ}C$ This means it rarely meets actual outdoor conditions. The solar spectrum always changes. So it is rare to fit the standard solar spectrum AM1 5G defined in ASTM G173-03 or IEC 60904-3. Thus spectral response of PV module is different depending on the material. so we estimated the variation of Isc at every minutes by comparing c-Si PV module with a-si PV module for outdoor conditions.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.894-903
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• 2019

An approach for collapse risk assessment is proposed to evaluate the vulnerability of electric cabinet in nuclear power plants. The lognormal approaches, namely maximum likelihood estimation and linear regression, are introduced to establish the fragility curves. These two fragility analyses are applied for the numerical models of cabinets considering various boundary conditions, which are expressed by representing restrained and anchored models at the base. The models have been built and verified using the system identification (SI) technique. The fundamental frequency of the electric cabinet is sensitive because of many attached devices. To bypass this complex problem, the average spectral acceleration $S_{\bar{a}}$ in the range of period that cover the first mode period is chosen as an intensity measure on the fragility function. The nonlinear time history analyses for cabinet are conducted using a suite of 40 ground motions. The obtained curves with different approaches are compared, and the variability of risk assessment is evaluated for restrained and anchored models. The fragility curves obtained for anchored model are found to be closer each other, compared to the fragility curves for restrained model. It is also found that the support boundary conditions played a significant role in acceleration response of cabinet.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.386-400
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• 2022

Seismic fragility analysis, a part of seismic probabilistic risk assessment (SPRA), is commonly used to establish the relationship between a representative property of earthquakes and the failure probability of a structure, component, or system. Current guidelines on the SPRA of nuclear power plants (NPPs) used worldwide mainly reflect the earthquake characteristics of the western United States. However, different earthquake characteristics may have a significant impact on the seismic fragility of a structure. Given the concern, this study aimed to investigate the effects of earthquake characteristics on the seismic fragility of concrete containments housing the OPR-1000 reactor. Earthquake time histories were created from 30 ground motions (including those of the 2016 Gyeongju earthquake) by spectral matching to the site-specific response spectrum of Hanbit nuclear power plants in South Korea. Fragility curves of the containment structure were determined under the linear response history analysis using a lumped-mass stick model and 30 ground motions, and were compared in terms of earthquake characteristics. The results showed that the median capacity and high confidence of low probability of failure (HCLPF) tended to highly depend on the sustained maximum acceleration (SMA), and increase when using the time histories which have lower SMA compared with the others.

• Current Optics and Photonics
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• v.5 no.6
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• pp.652-659
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• 2021

The theoretical analysis and optimization of extrinsic Fabry-Perot interferometer (EFPI) opticalfiber humidity sensors are deeply investigated. For a typical dual-cavity structure composed of an optical fiber and a humidity-sensitive membrane (HSM), the changes in refractive index (RI) and initial length are discussed for polymer materials and porous oxide materials when relative humidity (RH) increases. The typical interference spectrum is simulated at different RH using MATLAB. The spectral change caused by changing HSM RI and initial length are simulated simutineously, showing different influences on humidity response. To deeply investigate the influence on RH sensitivity, the typical response sensitivity curves for different HSM lengths and air-cavity lengths are simulated. The results show that the HSM is the vital factor. Short HSM length can improve the sensitivity, but for HSM RI and length the influences on sensitivity are opposite, because of the opposite spectral-shift trend. Deep discussion and an optimization method are provided to solve this problem. According to analysis, an opaque HSM is helpful to improve sensitivity. Furthermore, if using an opaque HSM, a short air cavity and long HSM length can improve the sensor's sensitivity These results provide deep understanding and some ideas for designing and optimizing highly sensitive EFPI fiber humidity sensors.

• Journal of Veterinary Science
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• v.24 no.5
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• pp.66.1-66.7
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• 2023

Two dogs presented with bilateral pattern-forming corneal opacity. Treatment with topical immunosuppressants was initiated after a complete ophthalmic examination. The response to treatment was assessed by analyzing serial images using slit-lamp biomicroscopy and spectral domain optical coherence tomography (SD-OCT). Both dogs responded to topical immunosuppressants; however, the lesions recurred once the treatment was abated or withdrawn. The most effective immunosuppressant in both dogs was 0.03% tacrolimus ointment. Early and continuous treatment with topical immunosuppressants may be necessary to improve corneal clarity and prevent scarring. SD-OCT could provide useful structural information regarding presumed immune-mediated keratitis and aid in monitoring treatment response.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.6
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• pp.1-8
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• 1999

Multi-carrier CDMA is a transmission scheme where data symbols are spread in the frequency domain with a spread code then transmitted using multiple carriers. It is robust against narrowband interference because of its long symbol duration. However, due to large sidebands of the rectangular window frequency response, subchannels spectrally overlap with neighboring subchannels, which leads to substantial intercarrier interference in a dispersive channel. In this paper, we consider a mult-carrier CDMA system where subchannel spectral containment is achiveved by M-band cosine modulated filter bank (CMFB). In CMFB based MC-CDMA, subchannel spectral containment is achieved using the filter bank of longer impulse response than that of conventional discrete Fourier transform (DFT) filter bank. We show that spectral containment feature of the CMFB based fading channel is analyzed using computer simulations.

• Journal of Korean Society of Transportation
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• v.33 no.4
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• pp.405-416
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• 2015

This paper developed a method analyze drivers' response characteristics using spectral analysis with car following data. Cross-correlation function and cross spectrum are produced by Fourier transform from speed fluctuations of leading vehicle and following vehicle during the designated time ${\tau}$. Based on the analysis data, a process to calculate the reaction time and stimulus-adaption index of following vehicle was developed and 170 cases of field data was applied. It was reported average of 0.654 and 2.091 seconds of stimulus-adaption index and reaction time respectively. In conclusion, the developed indexes might contribute to enhance vehicle control of autonomous vehicle more efficient and safer.