• ALGAE
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• v.30 no.1
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• pp.35-47
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• 2015

The marine sand-dwelling dinoflagellate Polykrikos lebourae possesses obvious gold-brown pigmented plastids as well as taeniocyst-nematocyst complex structures. Despite of the presence of the visible plastids, previous attempts to establish this species in culture all failed and thus the unavailability of cultures of this species has posed a major obstacle to further detailed exploration of ecophysiology of the dinoflagellate. Here, we isolated P. lebourae from sandy sediment of an intertidal flat on Korean western coast, successfully established it in culture, and have been maintaining the stock culture over the past 3 years. Using this stock culture, we explored phagotrophy and potential prey resources of P. lebourae, growth and grazing responses of P. lebourae to different prey organisms, the effect of prey concentration on growth and grazing rates and gross growth efficiency (GGE) of P. lebourae when fed three different prey organisms, and the growth kinetics of P. lebourae under different light regimes. P. lebourae captured prey cells using a tow filament and then phagocytized them through the posterior end. The dinoflagellate was capable of ingesting a broad range of prey species varying in size, but not all prey species tested in this study supported its sustained growth. GGE of P. lebourae was extremely high at low prey concentration and moderate or low at high prey concentrations, indicating that P. lebourae grows heterotrophically at high prey concentrations but its growth seems to be more dependent on a certain growth factor or photosynthesis of plastids derived from the prey. In the presence of prey in excess, P. lebourae grew well at moderate light intensity of $40{\mu}mol$ photons $m^{-2}s^{-1}$, but did not grow at dim and high (10 or $120{\mu}mol$ photons $m^{-2}s^{-1}$) light intensities. Our results suggest that the benthic dinoflagellate P. lebourae is an obligate mixotroph, requiring both prey and light for sustained growth and survival.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.4
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• pp.333-345
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• 2017

The potato tuber is known as a rich source of essential nutrients, used throughout the world. Although potato-breeding programs share some priorities, the major objective is to increase the genetic potential for yield through breeding or to eliminate hazards that reduce yield. Glycoalkaloids, which are considered a serious hazard to human health, accumulate naturally in potatoes during growth, harvesting, transportation, and storage. Here, we used the AMMI (additive main effects and multiplicative interaction) and GGE (Genotype main effect and genotype by environment interaction) biplot model, to evaluate tuber yield stability and glycoalkaloid content in six potato cultivars across three locations during 2012/2013. The environment on tuber yield had the greatest effect and accounted for 33.0% of the total sum squares; genotypes accounted for 3.8% and $G{\times}E$ interaction accounted for 11.1% which is the nest highest contribution. Conversely, the genotype on glycoalkaloid had the greatest effect and accounted for 82.4% of the total sum squares), whereas environment and $G{\times}E$ effects on this trait accounted for only 0.4% and 3.7%, respectively. Furthermore, potato genotype 'Superior', which covers most of the cultivated area, exhibited high yield performance with stability. 'Goun', which showed lower glycoalkaloid content, was the most suitable and desirable genotype. Results showed that, while tuber yield was more affected by the environment, glycoalkaloid content was more dependent on genotype. Further, the use of the AMMI and GGE biplot model generated more interactive visuals, facilitated the identification of superior genotypes, and suggested decisions on a variety of recommendations for specific environments.

• Geophysics and Geophysical Exploration
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• v.14 no.1
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• pp.116-120
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• 2011

Radioelement ratios are useful for mapping subtle variations in radiometric signatures in map data. But the conventional method for calculating radioelement ratios has the significant limitation that if just one of the radioelements comprising the ratio has a small spread of concentration estimates relative to its mean, then it will not contribute significantly to the ratio map. However, if both the numerator and denominator are first normalised to approximately the same mean and spread prior to ratioing, then they will contribute equally to the enhancement of the differences between them across the map area.

• Steel and Composite Structures
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• v.2 no.3
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• pp.161-170
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• 2002

The problem of the elastic buckling of a cylindrical liquid-storage tank subject to horizontal earthquake loading is considered. An equivalent static loading is used to represent the dynamic effect. A theoretical solution based on the nonlinear Fl$\ddot{u}$gge shell equations is developed, and numerical results are found using the new differential quadrature method. A second solution is obtained using the finite element package ADINA. A major motivation of the study was to show that the new method can serve to verify finite element solutions for cylindrical shell buckling problems. For this purpose the paper concludes with a comparison of buckling results for a number of cases covering a wide range in tank geometry.

• Geophysics and Geophysical Exploration
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• v.16 no.4
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• pp.268-274
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• 2013

Continuous seismic observation of volcanic earthquakes related to migration of magma or gas, is one of the most important methods used to monitor active volcanoes. In this review paper, we introduce the characteristics of volcanic earthquakes and their classification based on locations of foci, waveforms, frequencies, lithology, and source mechanisms. We also present some examples of successful warnings of volcanic eruptions and the present status of some observations of volcanic earthquakes in Japan, the United States, Italy, and New Zealand.

• Steel and Composite Structures
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• v.34 no.4
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• pp.599-613
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• 2020

In this article, free vibration attributes of double-walled carbon nanotubes based on nonlocal elastic shell model have been investigated. For this purpose, a nonlocal Flügge shell model is established to observe the small scale effect. The wave propagation is employed to frame the governing equations as eigenvalue system. The influence of nonlocal parameter subjected to different end supports has been overtly examined. A suitable choice of material properties and nonlocal parameter been focused to analyze the vibration characteristics. The new set of inner and outer tubes radii investigated in detail against aspect ratio and length. The dominance of boundary conditions via nonlocal parameter is shown graphically. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.

• Geophysics and Geophysical Exploration
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• v.15 no.4
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• pp.245-248
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• 2012

Two dimensional Fourier transform can be used for the upward continuation of gravity or magnetic field data acquired at given altitude over a rectangular area. Earth's curvature is often neglected in most potential field continuations, however, it should be considered over several hundred kilometer field area. In this study, we developed a new method retaining terms of Earth's curvature to better perform the continuation of potential field on spherical patch area.

• Journal of Power System Engineering
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• v.9 no.3
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• pp.58-65
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• 2005

This paper deals with the free vibrations of truncated conical shell with uniform thickness by the transfer influence coefficient method. The classical thin shell theory based upon the $Fl\ddot{u}gge$ theory is assumed and the governing equations of a conical shell are written as a coupled set of first order differential equations using the transfer matrix. The Runge-Kutta-Gill integration and bisection method are used to solve the governing differential equations and to compute the eigenvalues respectively. The natural frequencies and corresponding mode shapes are calculated numerically for the truncated conical shell with any combination of boundary conditions at the edges. And all boundary conditions and the intermediate supports between conical shell and foundation could be treated only by adequately varying the values of the spring constants. Numerical results are compared with existing exact and numerical solutions of other methods.

• Geophysics and Geophysical Exploration
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• v.26 no.4
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• pp.238-267
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• 2023

Studies on Earth's rotation and tide since the 19th century are briefly summarized. The theories of precession, nutation, polar motion, and periodic/secular changes in the rate of rotation are described individually. In addition, a brief review of the Milankovitch theory - the hypothesis of the relationship between the Earth's spin/orbital rotational state and the ice ages - is given. Finally, Earth's tides and their theoretical models are briefly explained. Some detailed technical content is summarized in the appendices.

• The Korean Journal of Air & Space Law and Policy
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• v.30 no.1
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• pp.303-325
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• 2015

The latest slogan put forth by the international space community is the safety, security, and sustainability of outer space activities. The security of outer space activities, in particular, would be defined as the secure state from space-based threats. The latter comprises passive threats (such as collision with other satellites and space debris) and aggressive threats (such as electromagnetic interference, arms race on the earth or in outer space, and military attacks). Has outer space been used for military purposes in practice? If so, does international law regulate the military space activities it? The use of outer space for military purposes is referred to as space militarization and space weaponisation. Satellites has been used in Gulf War, Kosovo War, and Afghan War, recently, and research and development on space weapons are under way. Since only the placement of weapons of mass destruction on orbit around the earth is prohibited in accordance with 1967 Outer Space Treaty, it may be asked whether other weapons may be placed on orbit. It will be necessary to analyze the stance of on the above question, by studying UN space-related treaties including UN Charter. New international space norms represented by PPWT, ICoC, and UN GGE Report are at the center of progressive development of international law. In conclusion, the author will signpost the various points on international norms to be codified on the use of outer space for military purposes.