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Full-scale tests and finite element analysis of arched corrugated steel roof under static loads

  • Wang, X.P.;Jiang, C.R.;Li, G.Q.;Wang, S.Y.
    • Steel and Composite Structures
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    • v.7 no.4
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    • pp.339-354
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    • 2007
  • Arched Corrugated Steel Roof (ACSR) is a kind of thin-walled steel shell, composing of arched panels with transverse small corrugations. Four full-scale W666 ACSR samples with 18m and 30m span were tested under full and half span static vertical uniform loads. Displacement, bearing capacities and failure modes of the four samples were measured. The web and bottom flange in ACSR with transverse small corrugations are simplified to anisotropic curved plates, and the equivalent tensile modulus, shear modulus and Poisson's ratio of 18m span ACSR were measured. Two 18 m-span W666 ACSR samples were analyzed with the Finite Element Analysis program ABAQUS. Base on the tests, the limit bearing capacity of ACSR is low, and for half span loading, it is 74-75% compared with the full span loading. When the testing load approached to the limit value, the bottom flange at the sample's bulge place locally buckled first, and then the whole arched roof collapsed suddenly. If the vertical loads apply along the full span, the deformation shape is symmetric, but the overall failure mode is asymmetric. For half span vertical loading, the deformation shape and the overall failure mode of the structure are asymmetric. The ACSR displacement under the vertical loads is large and the structural stiffness is low. There is a little difference between the FEM analysis results and testing data, showing the simplify method of small corrugations in ACSR and the building techniques of FEM models are rational and useful.

Experimental and analytical behaviour of composite slabs

  • Lopes, Emanuel;Simoes, Rui
    • Steel and Composite Structures
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    • v.8 no.5
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    • pp.361-388
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    • 2008
  • The Eurocode 4 presents some negative aspects in the design of composite slabs by the m-k Method or the Partial Connection Method. On one hand, the component chemical adherence is not accounted for in the connection between the profiled steel sheet and the concrete. On the other hand, the application of these methods requires some fitting parameters that must be determined by full scale tests. In this paper, the Eurocode 4 methods are compared with a method developed at the Federal Polytechnic School of Lausanne, based on pullout tests, which can be a valid alternative. Hence, in order to calculate the necessary parameters for the three methods, several tests have been performed such as the full scale test described in Eurocode 4 and pull-out tests. This last type of tests is of small dimensions and implicates lower costs. Finally, a full-scale test of a steel-concrete composite slab with a generic loading is presented, with the goal of verifying the analytical formulation.

Unified Estimations for Parameter Changes in the Uniform Distribution

  • Lee, Changsoo;Chang, Chuseock;Park, Yangwoo
    • Communications for Statistical Applications and Methods
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    • v.10 no.1
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    • pp.145-151
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    • 2003
  • We shall propose several estimators for the scale parameter in the uniform distribution when the parameter is functions of a known exposure level, and obtain expectations and variances for their proposed estimators. And we shall compare numerically relative efficiencies for proposed estimators of the scale parameter in the small sample sizes.

Utilization of UAV Remote Sensing in Small-scale Field Experiment : Case Study in Evaluation of Plat-based LAI for Sweetcorn Production

  • Hyunjin Jung;Rongling Ye;Yang Yi;Naoyuki Hashimoto;Shuhei Yamamoto;Koki Homma
    • Proceedings of the Korean Society of Crop Science Conference
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    • 2022.10a
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    • pp.75-75
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    • 2022
  • Traditional agriculture mostly focused on activity in the field, but current agriculture faces problems such as reduction of agricultural inputs, labor shortage and so on. Accordingly, traditional agricultural experiments generally considered the simple treatment effects, but current agricultural experiments need to consider the several and complicate treatment effects. To analyze such several and complicate treatment effects, data collection has the first priority. Remote sensing is a quite effective tool to collect information in agriculture, and recent easier availability of UAVs (Unmanned Aerial Vehicles) enhances the effectiveness. LAI (Leaf Area Index) is one of the most important information for evaluating the condition of crop growth. In this study, we utilized UAV with multispectral camera to evaluate plant-based LAI of sweetcorn in a small-scale field experiment and discussed the feasibility of a new experimental design to analyze the several and complicate treatment effects. The plant-based SR measured by UAV showed the highest correlation coefficient with LAI measured by a canopy analyzer in 2018 and 2019. Application of linear mix model showed that plant-based SR data had higher detection power due to its huge number of data although SR was inferior to evaluate LAI than the canopy analyzer. The distribution of plant-based data also statistically revealed the border effect in treatment plots in the traditional experimental design. These results suggest that remote sensing with UAVs has the advantage even in a small-scale experimental plot and has a possibility to provide a new experimental design if combined with various analytical applications such as plant size, shape, and color.

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A design of Cooperative Instruction Model based on WWW to improve learning attitude in a small-scale class (소인수학급에서 학습태도에 변화를 주는 웹기반 협동수업모델의 설계)

  • Sung, Young-Hoon;Lee, Jae-Inn
    • Journal of The Korean Association of Information Education
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    • v.6 no.2
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    • pp.154-162
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    • 2002
  • In a small-scale class, children gradually lose interests in studying and develop negative and passive attitudes in class activities due to the uniform education. Although many cooperative instruction WBI models are studied and designed, there has not been any research on cooperative instruction model appropriate for a small-scale class. In this study, instructors participate in classes, each in connection with other small-scale classes, and WWW based cooperative instruction model, WIEZ, which can affect students' learning attitude on long-term basis, was designed and embodied. Currently, WIEZ is being under experimental test in three schools at Kyung-nam where instructors design classes, and students divided into groups participate in classes in this system.

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Interfering Elements in Observation Research on Occupational Health Nursing Services Applied to Small-scale-enterprises of Korea (소규모 사업장의 보건관리 간호업무에 대한 관찰연구에서의 장애요인)

  • YOO, Kyung-Hae
    • Korean Journal of Occupational Health Nursing
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    • v.9 no.1
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    • pp.56-61
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    • 2000
  • This study was done in an attempt to reveal those factors interfering with the observation study. Three trained research assistants collected data by observing the two occupational health nurses working in the small scale enterprises on the 3rd and 10th of February, 1999. The first observation was performed on the 3rd of February without observation guidance. Guidance was given during the second observation on the 10th of February. These data were compared between reporters in nursing services of 'Workplace visiting', 'Health counselling' and 'Blood pressure checking' according to nursing time and frequency. These areas were chosen because these activities were regarded as clearly identifiable by observers in contrast to the other performances. The data showed inconsistency between reporters. However, they were reduced when reporters observed nurses with guidance, although there were still minor differences between data in time and frequency. Discussions were carried out to find possible reasons for these differences. The causes were mainly attributed to the difficulty in workplace conditions to observe, the work specificity of nurses visiting each workplace and the delicate situation between nurses and observers when reporters were travelling in the nurse's car. Therefore, the results suggest that the observation method applied to the nursing service research at small-scale enterprises should be more concerned about the selection of appropriate workplace and operational definition of nursing activity in order to more precisely measure nurses' attitudes.

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A Microgrid Operation based on a Power Market Environment

  • Kim, Hak-Man;Kinoshita, Tetsuo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.23 no.11
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    • pp.61-68
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    • 2009
  • A Microgrid is a private small-scale power system composed of distributed energy resources (DERs), storage devices and loads. And it is expected that the Microgrid will come into wide use in the near future. For this, the establishment of the Microgrid operation methodology is a very important problem. Especially, the Microgrid is greatly different from existing private small-scale power systems because of the multiple participants. Therefore, the Microgrid operation considered various requirements according to multiple participants is more complicated than the operation of existing private small-scale power systems. In this paper, Microgrid operation methodology based on a market environment is suggested. Through case studies, the effectiveness of the suggested methodology is verified.

Characterizing Small-scale Mechanical Behaviors of Heat-treated Materials with Nanoindentation Technique (나노압입시험법을 이용한 열처리 소재의 미소 변형 거동 평가)

  • Choi, In-Chul
    • Journal of the Korean Society for Heat Treatment
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    • v.33 no.2
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    • pp.72-79
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    • 2020
  • To improve the mechanical properties of most structural materials for industrial applications, the control of microstructure is essential by heat treatment process or plastic deformation process. Since the mechanical behavior of structural materials is significantly influenced by their microstructure, it is inevitably preceded to understand the relationship between microstructure and strengthening mechanisms of materials which can be easily changed by heat treatment. In this regard, the nanoindentation test is useful technique for analyzing the influence of the localized microstructural change on small-scale mechanical behavior of various structural materials. Here, the interesting studies performed on various heat-treated materials are reviewed with focus on micromechanical properties obtained by nanoindentation, which are reported in the available literature.

Stress Intensity Factors for a Crack in a Nonlinear Electrostrictive Material (비선형 전왜재료 내부의 균열에 대한 응력 확대계수)

  • Beom, Hyeon-Gyu;Jeong, Eun-Do
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.2
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    • pp.186-191
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    • 2001
  • A crack with electrically impermeable surfaces in an electrostrictive material subjected to uniform electric loading is analysed. The effect of electric yielding on stress intensity factor is investigated by using a small scale yielding model and a strip yield zone model. Complete forms of electric fields and elastic fields are derived by using complex function theory. The electrical yield zone shapes for two models are different each other. The two models, however, predict similar yield zone sizes under the small scale yielding conditions. It is found that the influence of electric yielding on the stress intensity factor is insensitive to the modeling of the electrical yield zone shape.

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