• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.5
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• pp.179-189
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• 2008

The object of this study is to develope a program with proposed numerical techniques for an optimal seismic control of structures using active tendon systems. Ricatti closed-loop algorithm has been applied to control the active tendon systems with time-delay problem. The optimal control is formulated as an optimization problem which is finding optimal weighting matrices by minimizing the quadratic performance index by SUMT. In order to find the optimal location of active tendons in structures, controllability index has been introduced. From numerical examples, the current optimal control technique with optimal location of tendons was suitable to control the seismic response of structures.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.17 no.1
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• pp.17-23
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• 2009

The purpose of this study is possibility of the heavy rainfall prediction using instability index. The convective instability index using this study is Convective Available Potential Energy(CAPE) concerned the growth energy of the storm, Bulk Richardson Number(BRN) concerned the type and strength of the storm, and Sotrm Relative Helicity(SRH) concerned maintenance of the storm. To verify the instability index, the simulation of heavy rainfall case experiment by Numerical Weather Prediction(NWP) model(MM5) are designed. The results of this study summarized that the heavy rainfall related to the high instability index and the proper combination of one more instability index made the higher heavy rainfall prediction.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.2
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• pp.70-74
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• 2004

There is a need to have a dredging index for decision of contaminated sediments dredging. Some differences from nation to nation were found in sediment quality guideline being applied by several nations because of economic level, environmental nature, and multiple uses. Therefore, it is not reasonable to adapt one guideline to be applied to sediments dredging. In this study, we developed dredging index by combining four numerical sets of sediment quality judgement into a quadrodiagram for prudential decisions. This newly developed dredging index was applied to the data obtained from Masan Bay before and after the dredging process. The quadrodiagrams of DI give us a nice graphical comparison and numerical values to explain the relative dredging effect under the circumstances of continuous input loadings. When the guideline value of DI is determined for the judgement of dredging considering social and economic impacts on local community, the DI value will be a scientific and reasonable tool in deciding dredging area and dredging depth.

• Journal of Ocean Engineering and Technology
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• v.22 no.2
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• pp.34-41
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• 2008

As a basic study for developing a forecasting/estimating system that predicts water quality changes when Deep Sea Water (DSW) drains to the ocean after using it, this study was carried out as follows: 1) numerical simulation of the present state at DSW developing region in the East sea using SWEM, 2) numerical prediction of water quality changes by effluent DSW, 3) analysis of influence degree 'With defined DEI (DSW effect index) at F station. On the whole, when DSW drained to the ocean, Chl-a, COD and water-temperature were decreased and DIN, DIP and DO were increased by effluent DSW, and Salinity was steady. According to analysis of influence degree, the influence degree of DIN was the highest and it was high in order of Chl-a, COD, Water-temperature, DO, DIP and Salinity. The influence degree classified by DSW effluent position was predicted that suiface outflow was lower than bottom outflow. Ad When DSW discharge increased 10 times, the influence degree increased about $5{\sim}14$ times.

• Journal of the Chungcheong Mathematical Society
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• v.19 no.2
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• pp.123-131
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• 2006

In this paper, a numerical programming for Liapunov index of differential equations with periodic coefficients depending on parameters is given. The associated equations are given at first, then existence of periodic solutions to the associated equations is proved in this paper. And we compute periodic solution u(t) of the associated equations. Finally, we give the error of approximate calculation.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.786-790
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• 1987

An optimization problem minimizing n given time-weighted performance index for discrete-time linear multi-input systems is investigated for the prespecified closed-loop eigenvalues. Necessary conditions for an optimality of the controller that satisfies the specified closed-loop eigenvalues are derived. A computational algorithm solving the optimal constant feedback gain is presented and a numerical example is given to show the effect of a time-weighted performance index on the transient responses.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.11
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• pp.40-48
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• 1992

The wave-kinetic numerical method is used in simulating the irradiance scintillations of optical wave through a two-dimensional random medium containing weak Gaussian fluctuations of the refractive index. The results are compared to existing analytical or numerical results. The wave-kinetic method is a phase-space ray-tracing method for certain key ray trajectories, and the irradiance is calculated by reconstructing the entire beam from these trajectories. The strength of the wave-kinetic method lies in the fact that it can be applied to any type of random media.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.13-14
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• 2007

• Journal of Korean Society of Forest Science
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• v.21 no.1
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• pp.47-51
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• 1974

In order to prove the similarity relationships between the basic species of oak through Electronic Data Processing System(EDPS) and numerical analysis, The analized species and datas were selected from the list of morphological observation in the thesis of T.B. Lee, 1961, "Phytogenetic study of the subgenus Lepidobalanus of the genus Quercus in Korea", and were coded by categories shown in Table 1. The value in the list were transformed into hundred percentage to standardize the observational value by each code into dimensionless. The similarity index between species were computed through formula of non-metric coefficient, $N_{jk}=\sum\limits_{i=1}^{n}\(\frac{{\mid}x_{ij}-x_{ik}{\mid}}{x_{ij}+x_{ik}}\)$, using the UNiVAC-1106, at National Computer Center. Quercus aliena, by analysis result, is most similar to Q. mongolica with the similarity index, 71.6 and Q. dentata is most far apart from Q. serrata in the relationship with index, 121.4. The above thesis of Professor, T. Lee, are closely similar with the result of this research study. But, their similar relationship are proved in quantity through numerical method in our research study. In addition, The relationships among Q. mongolica, Q. aliena and Q. serrata are found to be very similar, but Q. dentata to be enough far in similarity to other species by dendrogram shown at Fig. 1. The numerical classification through EDPS is found to be suitable method also applicable to the plant taxonomy.

• Atmosphere
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• v.28 no.4
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• pp.403-414
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• 2018

Predictability of Northern Hemisphere blocking in the Korea Meteorological Administration (KMA) Global Data Assimilation and Prediction System (GDAPS) is evaluated for the period of July 2016 to May 2017. Using the operational model output, blocking is defined by a meridional gradient reversal of 500-hPa geopotential height as Tibaldi-Molteni Index. Its predictability is quantified by computing the critical success index and bias score against ERA-Interim data. It turns out that Northwest Pacific blockings, among others, are reasonably well predicted with a forecast lead time of 2~3 days. The highest prediction skill is found in spring with 3.5 lead days, whereas the lowest prediction skill is observed in autumn with 2.25 lead days. Although further analyses are needed with longer dataset, this result suggests that Northern Hemisphere blocking is not well predicted in the operational weather prediction model beyond a short-term weather prediction limit. In the spring, summer, and autumn periods, there was a tendency to overestimate the Western North Pacific blocking.