• Wind and Structures
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• v.29 no.5
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• pp.339-359
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• 2019

Pre-stressed concrete poles are among the supporting systems used to support transmission lines. It is essential to protect transmission line systems from harsh environmental attacks such as downburst wind events. Typically, these poles are designed to resist synoptic wind loading as current codes do not address high wind events in the form of downbursts. In the current study, the behavior of guyed pre-stressed concrete Transmission lines is studied under downburst loads. To the best of the authors' knowledge, this study is the first investigation to assess the behaviour of guyed pre-stressed concrete poles under downburst events. Due to the localized nature of those events, identifying the critical locations and parameters leading to peak forces on the poles is a challenging task. To overcome this challenge, an in-house built numerical model is developed incorporating the following: (1) a three-dimensional downburst wind field previously developed and validated using computational fluid dynamics simulations; (2) a computationally efficient analytical technique previously developed and validated to predict the non-linear behaviour of the conductors including the effects of the pretension force, sagging, insulator's stiffness and the non-uniform distribution of wind loads, and (3) a non-linear finite element model utilized to simulate the structural behaviour of the guyed pre-stressed concrete pole considering material nonlinearity. A parametric study is conducted by varying the downbursts locations relative to the guyed pole while considering three different span values. The results of this parametric study are utilized to identify critical downburst configurations leading to peak straining actions on the pole and the guys. This is followed by comparing the obtained critical load cases to new load cases proposed to ASCE-74 loading committee. A non-linear failure analysis is then conducted for the three considered guyed pre-stressed concrete transmission line systems to determine the downburst jet velocity at which the pole systems fail.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.3
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• pp.57-66
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• 2023

In order to understand the economic feasibility of an offshore wind farm, this paper analyzed the differences in LCOE (levelized cost of energy) according to the support type and construction method of the substructure in terms of LCOE and sensitivity analysis was conducted according to the main components of LCOE. As for the site to be studied, the Southwest Offshore Wind Farm was selected, and the capital expenditures were calculated according to the size of the offshore wind farm and the installation unit. As a result of the sensitivity analysis, major components showed high sensitivity to availability, turbine related cost, weighted average cost of capital and balance of system related cost. Moreover, the post-piling jacket method, which was representatively applied to the substructure of the offshore wind farm in Korea, was selected as a basic plan to calculate the capital expenditures, and then the capital expenditures of the pre-piling jacket method and the tripod method were calculated and compared. As a result of analyzing the LCOE, it was confirmed that the pre-piling jacket method of the supporting structure lowers the LCOE and improves economic feasibility as the installation number of turbines increases.

• Korean Journal of Community Nutrition
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• v.18 no.3
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• pp.243-256
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• 2013

The purpose of this study was to evaluate the effectiveness of Centers for Child-care Foodservice Management (CCFSM)'s support on menu management in child-care centers and kindergartens by comparing two perspectives of pre-support vs. post-support and established vs. non-established. To evaluate dietary variety, we used methods that considered both Dietary Diversity Score (DDS) and Dietary Variety Score (DVS). For surveying pre-support and post-support state by CCFSM, we collected and analyzed menus of June and September, 2012, targeting 7 CCFSM supported institutions. Meanwhile, for surveying state in CCFSM established and non-established areas, we collected and analyzed menus of June, 2012, which were implemented in institutions in CCFSM established (181 places) and non-established (106 places) areas. The results of evaluation on the dietary support by CCFSM showed that post-supporting state by CCFSM (95.3%) was significantly higher than pre-supporting state (77.2%) (p < 0.001) and established areas (87.4%) were significantly higher than non-established ones (77.2%) (p < 0.05) on 'Meeting the DRI for infant'. Evaluation of dietary variety between pre- and post-support state by CCFSM showed that post-support state (total 77.3 point) was higher than pre-support state (total 76.4 point). Evaluation of dietary variety between established and non-established areas showed that established areas (total 81.1 point) were significantly higher than non-established ones (total 77.1 point) (p < 0.001). Therefore, it is considered that dietary support service conducted by CCFSM contributes to improve variety level of diet provided by child-care centers and kindergartens.

• Tunnel and Underground Space
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• v.15 no.1 s.54
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• pp.39-46
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• 2005

The RMR ratings, one by horizontal pre-boring in a tunnel and another by tunnel face mapping, are compared at the fault zone in a tunnel. Generally. the horizontal pre-borings were so effective as to forecast reasonably the supporting patterns after tunnel excavation. But the maximum difference in RMR ratings estimated by two methods was about 50 at a certain section of a tunnel. The differences were analyzed on each parameter of the RMR system: the rating differences were 24 in the condition of discontinuities, 15 in the RQD and 13 in the uniaxial compressive strength of rock. To minimize the gap between RMR by pre-borings and by face mappings, it is necessary to select the horizontal pre-boring location where tunnel stability could be critical and to evaluate in detail the sub-parameters of the condition of discontinuities.

• International Journal of Railway
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• v.5 no.4
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• pp.144-147
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• 2012

New transport technologies have been rapidly developed and various transport systems are ready to introduce. However, there no exists effective decision making tools for pre-feasibility studies on transport systems. The pre-feasibility studies should provide reliable solutions about whether a certain transport system is feasible or not by cost-benefit analysis and effectiveness test of enhancing regional economy. This study introduces the smart transport investment/information system (SMARTIS) for supporting decision making with ease, fast and reliable methods. The SMARTIS incorporates travel demand estimates into the process of feasibility studies with automatic data processing methods to give reliable solutions quickly. The SMARTIS is expected to be informative for transit agencies, planners, and operators.

• Earthquakes and Structures
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• v.8 no.3
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• pp.801-820
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• 2015

The seismic sequence which hit the Northern Italian territory in 2012 produced extensive damage to reinforced concrete (RC) precast buildings typically adopted as industrial facilities. The considered damaged buildings are constituted by one-storey precast structures with RC columns connected to the ground by means of isolated socket foundations. The roof structural layout is composed of pre-stressed RC beams supporting pre-stressed RC floor elements, both designed as simply supported beams. The observed damage pattern, already highlighted in previous earthquakes, is mainly related to insufficient connection strength and ductility or to the absence of mechanical devices, being the connections designed neglecting seismic loads or neglecting displacement and rotation compatibility between adjacent elements. Following the vulnerabilities emerged in past seismic events, the paper investigates the seismic performance of industrial facilities typical of the Italian territory. The European building code seismic assessment methodologies are presented and discussed, as well as the retrofit interventions required to achieve an appropriate level of seismic capacity. The assessment procedure and retrofit solutions are applied to a selected case study.

• Journal of information and communication convergence engineering
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• v.7 no.4
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• pp.480-488
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• 2009

A channel-shared modified accelerative pre-allocation wavelength division multiple access (CMAP-WDMA) media access control (MAC) has been proposed for metro-WDMA networks, as an extension of modified pre-allocation wavelength division multiple access (MAP-WDMA) MAC protocol. Similarly, CAP WDMA as an extension of accelerative pre-allocation wavelength division multiple access (AP-WDMA) MAC protocol. Performance of CMAP- and CAP-WDMA was extensively investigated under several channel sharing methods (CSMs), asymmetric traffic load patterns (TLPs), and non-uniform traffic distribution patterns (TDPs). The result showed that the channel utilization of the CMAP-WDMA always outperforms that of CAP-WDMA at the expense of longer channel access delay for channel shared case while CMAP-WDMA provided higher channel utilization at specific network conditions but always shorter channel access delay than CAP-WDMA for non-channel shared case. Additionally both for CMAP- and CAP-WDMA, determining an effective CSM is a critical design issue because TDPs and TLPs can be neither managed nor expected while CSM is manageable, and the CSM supporting the best channel utilization can be recommended.

• Journal of Educational Research in Mathematics
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• v.27 no.1
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• pp.137-156
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• 2017

This study was designed to gain insights into investigating pre-service secondary mathematics teacher education for technology integrated curriculum. The progressive expansion of supporting system for those education in US, TPACK, teacher belief, and analysis frameworks for teacher education program were explored. A survey on the technology courses in 42 mathematics education departments was analysed. Technology courses were not opened in 1/3 of the departments because of the lack of lecturers or objection of the faculty members. Common visions as well as curriculum realignment, financial supports are required for implementing technology integrated mathematics education

• Survey Research
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• v.12 no.1
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• pp.1-30
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• 2011

The purposes of the present study were to analyze correlation of vote behavior and attitude and vote intention in the pre-survey, and to investigate the efficient method of predicting the voting result from the pre-surveys. The previous attitude is measured by the support for the candidate, political self-confidence, self-efficacy and opinion on present issues. The vote intention is surveyed by the past election participation and degree of election interest. Real voting behavior is surveyed by the post enumeration, and the pre-survey and both post-survey are conducted to the same person to analyze the correlation of voting behavior and pre-survey. The real election participation is highly correlated with vote intention, election interest and past election participation. Almost respondents did not change the supporting candidate from the poll survey to the election vote. It is shown that the voting behavior at election of the nonrespondent of pre-survey can be predicted with the demographic charater and attitude of present issues.

• Coupled systems mechanics
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• v.9 no.2
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• pp.147-161
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• 2020

Constructive merging of "basic" systems of different behavior creates hybrid systems. In doing so, the structural elements are grouped according to the behavior in carrying the load into a geometric order that provides sufficient load and structure functionality and optimization of the material consumption. Applicable in all materializations and logical geometric forms is a transparent system suitable for the optimization of load-bearing structures. Research by individual authors gave insight into suitable system constellations from the aspect of load capacity and the approximatemethod of estimating the participation of partialstiffnesswithin the rigidity ofthe hybrid system. The obtained terms will continue to be the basisfor our own research of the influence of variable parameters on the behavior of hybrid systemsformed of glued laminated girder and cable of different geometric shapes. Previous research has shown that by applying the strut-type hybrid systems can increase the load capacity and reduce the deformability ofthe free girder.The implemented parametric analysis pointsto the basic parameterin the behavior of these systems-the rigidity ofindividual elements and the overallstiffnessofthe system.The basic idea ofpre-stressing is that, in the load system or individual load-bearing element, prior to application of the exploitation load, artificially challenge the forcesthatshould optimize the finalsystembehaviorin the overall load. Pre-stressing is possible only if the supporting system orsystem's element possesssufficientstrength orstiffness, orreaction to the imposed forces of pre-stressing. In this paper will be presented own research of the relationship of partial stiffness of strut-type hybrid systemsofdifferentgeometric forms.Conducted parametric analysisofhybridsystemswithandwithoutpre-stressing, and on the example of the glulam-steel strut-type hybrid system under realistic conditions of change in the moisture content ofthe wooden girder,resulted in accurate expressions and diagramssuitable for application in practice.