• Title/Summary/Keyword: Behavior-response performance

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Sparse Design Problem in Local Linear Quasi-likelihood Estimator (국소선형 준가능도 추정량의 자료 희박성 문제 해결방안)

  • Park, Dong-Ryeon
    • The Korean Journal of Applied Statistics
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    • v.20 no.1
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    • pp.133-145
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    • 2007
  • Local linear estimator has a number of advantages over the traditional kernel estimators. The better performance near boundaries is one of them. However, local linear estimator can produce erratic result in sparse regions in the realization of the design and to solve this problem much research has been done. Local linear quasi-likelihood estimator has many common properties with local linear estimator, and it turns out that sparse design can also lead local linear quasi-likelihood estimator to erratic behavior in practice. Several methods to solve this problem are proposed and their finite sample properties are compared by the simulation study.

Inelastic Behavior and Seismic Retrofit of Inverted V Braced Steel Frames (역V형 철골 가새골조의 비탄성거동 및 내진성능향상 방안에 관한 연구)

  • Kim, Nam Hoon;Lee, Cheol Ho
    • Journal of Korean Society of Steel Construction
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    • v.15 no.5 s.66
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    • pp.571-578
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    • 2003
  • An effective seismic retrofit scheme for inverted V braced (or chevron type) steel frames was proposed by studying the redistribution of forces in the post-buckling range. The steel frames with chevron bracing are highly prone to soft story response once the compression brace buckles under earthquake loading. This paper shows that the seismic performance of such frames could be significantly improved by supplying tie bars to redistribute the inelastic deformation demand over the height of the building. A practical design method of the retrofit tie bars was also proposed by considering the sequence of buckling occurrence.

Estimating Evapotranspiration of Rice Crop Using Neural Networks -Application of Back-propagation and Counter-propagation Algorithm- (신경회로망을 이용한 수도 증발산량 예측 -백프로파게이션과 카운터프로파게이션 알고리즘의 적용-)

  • 이남호;정하우
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.36 no.2
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    • pp.88-95
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    • 1994
  • This paper is to evaluate the applicability of neural networks to the estimation of evapotranspiration. Two neural networks were developed to forecast daily evapotranspiration of the rice crop with back-propagation and counter-propagation algorithm. The neural network trained by back-propagation algorithm with delta learning rule is a three-layer network with input, hidden, and output layers. The other network with counter-propagation algorithm is a four-layer network with input, normalizing, competitive, and output layers. Training neural networks was conducted using daily actual evapotranspiration of rice crop and daily climatic data such as mean temperature, sunshine hours, solar radiation, relative humidity, and pan evaporation. During the training, neural network parameters were calibrated. The trained networks were applied to a set of field data not used in the training. The created response of the back-propagation network was in good agreement with desired values and showed better performances than the counter-propagation network did. Evaluating the neural network performance indicates that the back-propagation neural network may be applied to the estimation of evapotranspiration of the rice crop. This study does not provide with a conclusive statement as to the ability of a neural network to evapotranspiration estimating. More detailed study is required for better understanding and evaluating the behavior of neural networks.

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Plastic Deformation Behavior of Structural Nano Metallic Materials (구조용 나노금속재료의 소성변형 특성)

  • Yoon, S.C.;Pham, Q.;Bock, C.H.;Kwak, E.J.;Kim, H.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.10a
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    • pp.25-26
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    • 2007
  • At the time when nanostructured materials (NSMs) are becoming a major focus of materials research, the attention of researchers is turning more to their mechanical performance. In contrast with conventional coarse grained materials, which are either strong or ductile, but rarely both at the same time, it is expected that with NSMs both high strength and ductility can be achieved and confirmed by several experimental studies. In spite of the significant interest and efforts in the mechanical properties of NSMs, deformation mechanisms during plastic deformation as well as elastic deformation are not well established yet. In this talk, the deformation mechanisms of NSMs under various grain sizes, temperatures and strain rates were investigated. It is based on recent modelling that appears to provide a conclusive description of the phenomenology and the mechanisms underlying the mechanical properties of NSMs. Based on the theoretical model that provides an adequate description of the grain size dependence of elasticity and plasticity covering all grain size range from coarse down to the nanoscale, the tensile deformation response of NSMs, especially focusing on the deformation mechanisms was investigated.

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Development of Modeling for Dynamic Response of EDF System (EDF 시스템의 동적 특성 연구를 위한 모델링 개발)

  • Han, Kyu Seung;Park, Sun Kyu;Lee, In Won
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.5 no.1
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    • pp.218-227
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    • 2001
  • The purpose of this study was to estimate that the relations of weathering speed and shear strength of granite soil by tracing the weathering depth of granite soil from the very moment of its cutting. The results obtained this follows : This paper is about seismic performance of the EDF(Electricite De France) system, that is among various base isolator. A rational modeling of EDF system has been presented that used Nllink element. We get theoretical solutions of equation of motion of the system and compared with numerical solutions using a finite element program. The unification modeling is made by comparing with behavior using Newmark-${\beta}$ method when input earthquake acceleration data. Thus, a verified modeling will apply bridge structures or multi-degree of-freedom systems.

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PI and Fuzzy Logic Controller Based 3-Phase 4-Wire Shunt Active Filters for the Mitigation of Current Harmonics with the Id-Iq Control Strategy

  • Mikkili, Suresh;Panda, Anup Kumar
    • Journal of Power Electronics
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    • v.11 no.6
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    • pp.914-921
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    • 2011
  • Commencing with incandescent light bulbs, every load today creates harmonics. Unfortunately, these loads vary with respect to their amount of harmonic content and their response to problems caused by harmonics. The prevalent difficulties with harmonics are voltage and current waveform distortions. In addition, Electronic equipment like computers, battery chargers, electronic ballasts, variable frequency drives, and switching mode power supplies generate perilous amounts of harmonics. Issues related to harmonics are of a greater concern to engineers and building designers because they do more than just distort voltage waveforms, they can overheat the building wiring, cause nuisance tripping, overheat transformer units, and cause random end-user equipment failures. Thus power quality is becoming more and more serious with each passing day. As a result, active power filters (APFs) have gained a lot of attention due to their excellent harmonic compensation. However, the performance of the active filters seems to have contradictions with different control techniques. The main objective of this paper is to analyze shunt active filters with fuzzy and pi controllers. To carry out this analysis, active and reactive current methods ($i_d-i_q$) are considered. Extensive simulations were carried out. The simulations were performed under balance, unbalanced and non sinusoidal conditions. The results validate the dynamic behavior of fuzzy logic controllers over PI controllers.

A Study on the Analysis of 3 Dimensional Substrate Behaviour of Complex Environmental Deterioration and the Analysis of Results (방수재료 및 공법의 내구성 평가를 위한 복합열화분석용 3차원 거동대응 시험결과)

  • Song, Je-Young;Seo, Hyun-Jae;Choi, Eun-Kyu;Lee, Jung-Hun;Kim, Byoungil;Oh, Sang-Keun
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2018.11a
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    • pp.189-190
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    • 2018
  • KS standards mostly relate to single component material evaluation, so in cases of underground structure environments, most cannot predict the existing composite forms of deterioration, resulting in the applied waterproofing materials becoming unable to respond to these damaging factors. Current domestic waterproofing market in Korea mainly uses single-ply waterproofing materials comprised of coatings or waterproof sheets and two or more-ply composite waterproofing methods. In order to evaluate these types of composite waterproofing systems, a new test equipment and method that incorporates various deterioration conditions (joint displacement, chemical exposure, water pressure etc) was developed. In a comparison testing, the results showed that flexible type materials have higher response performance towards joint displacement than the hardened material.

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Seismic Behavior and Performance Assesment of a One-story Building with a Flexible Diaphragm (유연한 지붕으로 된 단층 구조물의 지진 거동과 성능 분석)

  • ;;Donald W. White
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.16 no.4
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    • pp.377-386
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    • 2003
  • The proposed simplified MDOF model is applied to a half-scale single-story reinforced masonry test building with a single diagonally-sheathed diaphragm. Comparisons of analytical studies to experimental tests can be valuable for understanding the seismic response of these types of buildings and for determining the qualities and limitations of the simplified models. A model calibration process is performed in this paper to determine the required structural properties based on the elastic and inelastic test responses for test building. This approach is necessary since established methods to determine the in-plane and out-of-plane stiffness, strength, and hysteresis do not exist.

Evolutionary computational approaches for data-driven modeling of multi-dimensional memory-dependent systems

  • Bolourchi, Ali;Masri, Sami F.
    • Smart Structures and Systems
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    • v.15 no.3
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    • pp.897-911
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    • 2015
  • This study presents a novel approach based on advancements in Evolutionary Computation for data-driven modeling of complex multi-dimensional memory-dependent systems. The investigated example is a benchmark coupled three-dimensional system that incorporates 6 Bouc-Wen elements, and is subjected to external excitations at three points. The proposed technique of this research adapts Genetic Programming for discovering the optimum structure of the differential equation of an auxiliary variable associated with every specific degree-of-freedom of this system that integrates the imposed effect of vibrations at all other degrees-of-freedom. After the termination of the first phase of the optimization process, a system of differential equations is formed that represent the multi-dimensional hysteretic system. Then, the parameters of this system of differential equations are optimized in the second phase using Genetic Algorithms to yield accurate response estimates globally, because the separately obtained differential equations are coupled essentially, and their true performance can be assessed only when the entire system of coupled differential equations is solved. The resultant model after the second phase of optimization is a low-order low-complexity surrogate computational model that represents the investigated three-dimensional memory-dependent system. Hence, this research presents a promising data-driven modeling technique for obtaining optimized representative models for multi-dimensional hysteretic systems that yield reasonably accurate results, and can be generalized to many problems, in various fields, ranging from engineering to economics as well as biology.

Seismic behavior of frames with innovative energy dissipation systems (FUSEIS 1-1)

  • Dougka, Georgia;Dimakogianni, Danai;Vayas, Ioannis
    • Earthquakes and Structures
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    • v.6 no.5
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    • pp.561-580
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    • 2014
  • After strong earthquakes conventional frames used worldwide in multi - story steel buildings (e.g. moment resisting frames) are not well positioned according to reparability. Two innovative systems for seismic resistant steel frames incorporated with dissipative fuses were developed within the European Research Program "FUSEIS" (Vayas et al. 2013). The first, FUSEIS1, resembles a vertical Vierendeel beam and is composed of two closely spaced strong columns rigidly connected to multiple beams. In the second system, FUSEIS2, a discontinuity is introduced in the composite beams of a moment resisting frame and the dissipative devices are steel plates connecting the two parts. The FUSEIS system is able to dissipate energy by means of inelastic deformations in the fuses and combines ductility and architectural transparency with stiffness. In case of strong earthquakes damage concentrates only in the fuses which behave as self-centering systems able to return the structure to its initial undeformed shape. Repair work after such an event is limited only to replacing the fuses. Experimental and numerical investigations were performed to study the response of the fuses system. Code relevant design rules for the seismic design of frames with dissipative FUSEIS and practical recommendations on the selection of the appropriate fuses as a function of the most important parameters and member verifications have been formulated and are included in a Design Guide. This article presents the design and performance of building frames with FUSEIS 1-1 based on models calibrated on the experimental results.