• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.2
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• pp.85-93
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• 2024

In this paper, we propose a method for establishing a state-space equation model for the motion analysis of floating structures subjected to wave loads, by applying system-identification techniques. Traditionally, the motion of floating structures has been analyzed in the time domain by integrating the Cummins equation over time, which utilizes a convolution integral term to account for the effects of the retardation function. State-space equation models have been studied as a way to efficiently solve floating-motion equations in the time domain. The proposed approach outlines a procedure to derive the target transfer function for the load-displacement input/output relationship in the frequency domain and subsequently determine the state-space equation that closely approximates it. To obtain the state-space equation, the method employs the N4SID system-identification method and an optimization approach that treats the coefficients of the numerator and denominator polynomials as design variables. To illustrate the effectiveness of the proposed method, we applied it to the analysis of a single-degree-of-freedom model and the motion of a six-degree-of-freedom barge. Our findings demonstrate that the presented state-space equation model aligns well with the existing analysis results in both the frequency and time domains. Notably, the method ensures computational accuracy in the time-domain analysis while significantly reducing the calculation time.

• Journal of Plant Biotechnology
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• v.46 no.1
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• pp.32-36
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• 2019

Calla lilies (Zantedeschia spp.) are monocotyledonous ornamental plants which belongs to the Araceae family. After the release of elite calla cultivar, an efficient propagation system is needed for commercial use. Despite the use of conventional propagation methods such as splitting of tubers and rhizomes of calla, rapid and efficient propagation system should be developed. In order to achieve this goal, stem segments contained apical meristems derived from calla lily cultivar (cv. Gag-si) were cultured on Murashige and Skoog (MS) medium supplemented with various concentrations of cytokinin and auxin. This was aimed at inducing embryogenic calluses, shoots and multiple shoots. As a result, about 25% of induction rates of yellow embryogenic calluses were observed with MS medium containing both $0.5mg{\cdot}L^{-1}\;NAA$ and $1.5mg{\cdot}L^{-1}\;BA$ as growth regulators. In the experiments involving the regeneration from embryogenic calluses through shoot formation, MS medium supplemented with $0.5mg{\cdot}L^{-1}\;IAA$ and $2.0mg{\cdot}L^{-1}\;BA$ showed the highest rates at approximately 85 ~ 90% with regard to the formation of shoots in calla. Moreover, multiple shoots needed for rapid propagation were generated when explants were cultured on MS medium supplemented with $0.5mg{\cdot}L^{-1}\;IAA$ and $2.0mg{\cdot}L^{-1}\;BA$ with 40% of formation rate. In this study, the combination of auxin and cytokinin showed positive effects on both the induction of embryogenic calluses, the formation of shoots as well as multiple shoots in calla. The regeneration system described here can contribute to the development of breeding programs of calla in the future.