• Title/Summary/Keyword: WTS

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WTS-04

  • 양준규
    • TTA Journal
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    • s.96
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    • pp.138-147
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    • 2004

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Vibration-based structural health monitoring for offshore wind turbines - Experimental validation of stochastic subspace algorithms

  • Kraemer, Peter;Friedmanna, Herbert
    • Wind and Structures
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    • v.21 no.6
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    • pp.693-707
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    • 2015

  • The efficiency of wind turbines (WT) is primarily reflected in their ability to generate electricity at any time. Downtimes of WTs due to "conventional" inspections are cost-intensive and undesirable for investors. For this reason, there is a need for structural health monitoring (SHM) systems, to enable service and maintenance on demand and to increase the inspection intervals. In general, monitoring increases the cost effectiveness of WTs. This publication concentrates on the application of two vibration-based SHM algorithms for stability and structural change monitoring of offshore WTs. Only data driven, output-only algorithms based on stochastic subspace identification (SSI) in time domain are considered. The centerpiece of this paper deals with the rough mathematical description of the dynamic behavior of offshore WTs and with the basic presentation of stochastic subspace-based algorithms and their application to these structures. Due to the early stage of the industrial application of SHM on offshore WT on the one side and the required confidentiality to the plant manufacturer and operator on the other side, up to now it is not possible to analyze different isolated structural damages resp. changes in a systematic manner, directly by means of in-situ measurement and to make these "acknowledgements" publicly available. For this reason, the sensitivity of the methods for monitoring purposes are demonstrated through their application on long time measurements from a 1:10 large scale test rig of an offshore WT under different conditions: undamaged, different levels of loosened bolt connections between tower parts, different levels of fouling, scouring and structure inclination. The limitation and further requirements for the approaches and their applicability on real foundations are discussed along the paper.

  • https://doi.org/10.12989/was.2015.21.6.693 인용 KSCI

The Effect of Regulatory Focus and Product Type on the Difference in Acceptable Prices between Buyers and Sellers (구매자와 판매자의 용의가격 차이에 제품유형과 소비자의 목적지향성이 미치는 영향)

  • Jun, Sung Youl;Ju, Tae Wook;Cho, Hyo Ryung
    • Asia Marketing Journal
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    • v.10 no.1
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    • pp.65-94
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    • 2008

  • This study examines the generalizability of the existing research in an on-line auction situation which suggests that there exist a gap between buyer's willing-to-pay price(WTP) and seller's willing-to-sell price(WTS) about the same product due to the endowment effect and consumers' loss aversion propensity. At the same time, this study also identifies and examines the potential moderating factors for the effect such as product type and consumer's goal orientation based on existing theories about consumers' gain-loss heuristics. The results show that WTS is consistently higher than WTP, and that such gap gets more pronounced when the target product is hedonic vs. utilitarian and when consumers have prevention goals vs. promotion goals. Lastly, limitations and managerial implications of this study is discussed.

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Relationships between levels of heterotrophic plate count bacteria and endotoxin in point-of-use water treatment systems

  • Moon, Kyong-Whan;Kim, Young-Whan;Shon, Jong-Ryeul
    • Proceedings of the Korean Environmental Health Society Conference
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    • 2003.06a
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    • pp.132-135
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    • 2003

  • Endotoxin concentrations were measured from 69 point-of-use(POU) water treatment system(WTS) by using Limulus amebocyte lysate(LAL) assay, and the results were compared to heterotrophic bacterial data. Endotoxin concentrations in all POU WTS water samples and tap waters varied within the range 0.8-79.1EU mL$\^$-1/ and 0.1-3.4EU mL$\^$-1/, respectively, The correlations between endotoxin concentration and HPC bacteria from the water samples showed not significant(r=0.18).

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