• Structural Engineering and Mechanics
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• 제72권2호
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• pp.203-216
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• 2019

Reliability analysis of composite structures considering random variation of involved parameters is quite important as composite materials revealed large statistical variations in their mechanical properties. The reliability analysis of such structures by the first order reliability method (FORM) and Monte Carlo Simulation (MCS) based approach involves repetitive evaluations of performance function. The response surface method (RSM) based metamodeling technique has emerged as an effective solution to such problems. In the application of metamodeling for uncertainty quantification and reliability analysis of composite structures; the finite element model is usually formulated by either classical laminate theory or first order shear deformation theory. But such theories show significant error in calculating the structural responses of composite structures. The present study attempted to apply the RSM based MCS for reliability analysis of composite shell structures where the surrogate model is constructed using higher order shear deformation theory (HSDT) of composite structures considering the uncertainties in the material properties, load, ply thickness and radius of curvature of the shell structure. The sensitivity of responses of the shell is also obtained by RSM and finite element method based direct approach to elucidate the advantages of RSM for response sensitivity analysis. The reliability results obtained by the proposed RSM based MCS and FORM are compared with the accurate reliability analysis results obtained by the direct MCS by considering two numerical examples.

• E2M - 전기 전자와 첨단 소재
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• 제10권8호
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• pp.836-842
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• 1997

• Structural Engineering and Mechanics
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• 제81권4호
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• pp.429-441
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• 2022

A probabilistic assessment of the seismic-excited buildings with a multiple-tuned-mass-damper (MTMD) system is carried out in the presence of uncertainties of the structural model, MTMD system, and the stochastic model of the seismic excitations. A free search optimization procedure of the individual mass, stiffness and, damping parameters of the MTMD system based on the snap-drift cuckoo search (SDCS) optimization algorithm is proposed for the optimal design of the MTMD system. Considering a 10-story structure in three cases equipped with single tuned mass damper (STMS), 5-TMD and 10-TMD, sensitivity analyses are carried out using Sobol' indices based on the Monte Carlo simulation (MCS) method. Considering different seismic performance levels, the reliability analyses are done using MCS and kriging-based MCS methods. The results show the maximum structural responses are more affected by changes in the PGA and the stiffness coefficients of the structural floors and TMDs. The results indicate the kriging-based MCS method can estimate the accurate amount of failure probability by spending less time than the MCS. The results also show the MTMD gives a significant reduction in the structural failure probability. The effect of the MTMD on the reduction of the failure probability is remarkable in the performance levels of life safety and collapse prevention. The maximum drift of floors may be reduced for the nominal structural system by increasing the TMDs, however, the complexity of the MTMD model and increasing its corresponding uncertainty sources can be caused a slight increase in the failure probability of the structure.

• 융합정보논문지
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• 제10권5호
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• pp.1-7
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• 2020

본 논문은 수중 IoT 네트워크에서 센서의 전력 소비를 줄이고 네트워크의 처리량을 향상하는 수중 링크적응 방법을 제안한다. 링크 적응 방법의 하나인 AMC(Adaptive Modulation and Coding) 기술은 SNR(Signal Noise Rate)과 BER(Bit Error Rate)의 강한 상관관계를 이용하지만, 수중에 바로 적용하는 것은 어렵다. 따라서 수중 환경에 적합한 머신러닝 기반의 AMC 기술을 제안한다. 제안하는 MCS(Modulation Coding and Scheme) 예측 모델은 수중 채널 환경에서 목표 BER 값을 달성하기 위한 통신 방법을 예측한다. 예측된 통신 방법을 실제 수중 무선 통신에서 적용하는 것은 현실적으로 어렵기 때문에 본 논문에서는 높은 정확도의 BER 예측 모델을 사용해 MCS 예측 모델의 성능을 확인한다. 결과적으로 제안하는 AMC 기술은 통신 성공 확률을 올림으로써 머신러닝의 적용 가능성을 확인시켰다.

• 천문학회보
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• 제35권2호
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• pp.46.1-46.1
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• 2010

This work is a part of our project to establish a Website which provides a list of magnetic clouds (MCs) identified by WIND and ACE spacecraft. MCs are characterized by their magnetic fields that are well described by magnetic flux rope structures, whereas interplanetary coronal mass ejections (ICMEs) are interplanetary manifestations of coronal mass ejections (CMEs), usually identified by differences of plasma and magnetic field characteristics from those in the background solar wind. It is widely accepted that, while MCs are generally identified within ICMEs, the number of MCs are significantly lower than the number of ICMEs. In our effort to identify MCs, however, we have found that there was a big problem in identification method of MCs in previous works. Generally speaking, most of the previous surveys failed in identifying MCs which encounter the spacecraft at large distances from the MC axis, or near the surface of MC structures. In our survey, MCs are identified as the region of which magnetic fields are well described by appropriate flux rope models. Thus, we could selected over 45 MCs, in 1999 solar wind data for instance, while 33 ICMEs are listed in the Website of the ACE Science Center reported by Richardson and Cane.

• Nuclear Engineering and Technology
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• 제52권9호
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• pp.1907-1916
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• 2020

In this work, the depletion capability implemented in Monte Carlo code MCS is investigated to predict the isotopic compositions of spent nuclear fuel (SNF). By comparison of MCS calculation results to post irradiation examination (PIE) data obtained from one pressurized water reactor (PWR), the validation of this capability is conducted. The depletion analysis is performed with the ENDF/B-VII.1 library and a fuel assembly model. The transmutation equation is solved by the Chebyshev Rational Approximation Method (CRAM) with a depletion chain of 3820 isotopes. 18 actinides and 19 fission products are analyzed in 14 SNF samples. The effect of statistical uncertainties on the calculated number densities is discussed. On average, most of the actinides and fission products analyzed are predicted within ±6% of the experiment. MCS depletion results are also compared to other depletion codes based on publicly reported information in literature. The code-to-code analysis shows comparable accuracy. Overall, it is demonstrated that the depletion capability in MCS can be reliably applied in the prediction of SNF isotopic inventory.

• Journal of Pharmaceutical Investigation
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• 제34권5호
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• pp.393-399
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• 2004

For the efficient determination of activity against solid tumors, an in vitro tumor model that resembles the condition of in vivo solid tumors, is required. The purpose of this study was to establish a rapid culture method and viability assay for an in vitro 3-dimensional tumor model, multicellular spheroid (MCS). Among 12 human cancer cell lines, a few cell lines including DLD-1 (human colorectal carcinoma cells) formed fully compact MCS which was adequate for in vitro viability assay. DLD-1 MCS showed steady growth reaching $700\;{\mu}m$ diameter after 11 day culture. DLD-1 cells grown as MCS showed significant increase in $G_0/G_1$ phase compared to the monolayer cells (73.9% vs 45.7%), but necrotic regions or apoptotic cells were not observed. The cells cultured as MCS showed resistance to 5-FU (10.3 fold higher $IC_{50}$) compared to monolayers, however, tirapazamine (a hypotoxin) showed similar activity in both culture systems. In summary, MCS may be a valid in vitro model for activity screening of anticancer agents against human solid tumors and also exploitable for studying molecular markers of drug resistance in human solid tumors.

• 한국전기전자재료학회논문지
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• 제16권2호
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• pp.168-172
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• 2003

The electron transport coefficients in Air is analysed in range of E/Nvalues from 100~1000(Td) by a MCS and BE method. This paper have calculated W, ND$\sub$L/, ND$\sub$T/, Mean energy mixtures by N$_2$+O$_2$. The results gained that the values of the electron swarm parameters such as the electron drift velocity, longitudinal and transverse diffusion coefficients.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1995년도 추계학술발표회논문집
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• pp.53-59
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• 1995

The accurcy and the application limits of the Three-Curve Method(TCM) and Zonal Cavity Method(ZCM) are evaluated. Average illuminance values are calculated by TCM and ZCM for various lighting conditions using general Diffusing Luminaires and Direct Luminaires. These values are compared with the values from Monte-Carlo Simulation(MCS) for the same lighting conditions. Accuracy of MCS was proved by Moon's Analytical Method.

• 한국통신학회논문지
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• 제40권8호
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• pp.1613-1621
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• 2015

본 연구에서는 초고속 WLAN(Wireless LAN)인 IEEE 802.11ac 및 802.11ad 에서 처리율 향상을 위한 전송율 제어기법과 이에 따른 MCS(Modulation and Coding Scheme)의 적용방안을 제시한다. IEEE 802.11ac 및 802.11ad 표준은 기존의 IEEE 802.11b/g/a 무선 LAN표준과는 달리 송신측이 시간적으로 변하는 채널조건에 따라 전송율을 제어하여 처리율을 높일 수 있도록 하기 위해 많은 MCS 기능을 지원한다. 그러나 이들 표준에서는 전송율을 제어할 수 있는 알고리듬을 제시하고 있지 않으므로 본 연구에서는 전송율 제어 알고리듬에 대하여 살펴보고 MCS의 적용 방안을 제시한다. 특히 IEEE 802.11ac 무선 LAN의 DCF 처리율 성능을 에러를 갖는 채널 환경하에서 분석하기 위해 A-MPDU 기법이 활용되었고 패킷 에러율, 단말장치의 수, 프레임의 수, 프레임 페이로드 크기 및 전송 확률이 변수로 사용되었다.