• Ocean and Polar Research
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• v.39 no.2
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• pp.73-84
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• 2017

The probability distribution of ichthyoplankton is important for enhancing the precision of sampling while reducing unnecessary surveys. To estimate the ichthyoplankton detection proportion (IDP) and its margin of error (ME), the monitoring information of the chub mackerel's (Scomber japonicus) ichthyoplankton presence-absence sampling data has been were collected over approximately 30 years (from 1982 to 2011) in the Korean coastal seas. Based on the computed spatial distributions of the mackerel's IDP and ME, the confidence interval (CI) range, defined as 2 ME, decreases from approximately 80% to 40% as the sample size n increases from 4 to 24 and the ME is approximately 40% in the typical (seasonal survey) case n = 4 per year. The IDP and ME off Jeju Island are relatively high at the 0.5-degree smoothing level. After increasing the spatial smoothing level to 1.0-degree, the ME decreased, and the spatial distribution pattern also changed due to the over-smoothing effects. In this study, the 0.5-degree smoothing is more suitable for the distribution pattern than the 1.0-degree smoothing level. The area of the high IDP and the low ME on the mackerel's ichthyoplankton was similar to the estimated spawning ground in the Korean peninsula. This information could contribute to enhancing for the spawning ecology surveys.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.898-899
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• 2008

In this paper we propose a new method for obtaining two way switchable LCD. For this two domain vertical alignment LCD is used. A two way LCD is able to show different images on the same screen based on left and right perspectives. Viewing angle dependence of different grey levels of transmittance for the polar angles 0, +45 and -45 degree are also found out.

• Plant Resources
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• v.5 no.1
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• pp.17-28
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• 2002

Palynological characters such as pollen grain polar axis length (PL), pollen equatorial diameter (ED), colpus length, colpus width, and P/E ratio of six species of Quercus subgenus Lepidobalanus Endl. from Korea were studied. A significant interspecific variation, unequal distances between the species, and various degree of intraspecific variations were found. The taxonomic value of the pollen morphology parameters measured was found to vary according to species. These results suggest a possible relationship between parameters measured and ploidy level of the Quercus species studied.

• Journal of the Korean Mathematical Society
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• v.53 no.2
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• pp.461-473
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• 2016

Let C be a projective plane curve of degree d whose singularities are all isolated. Suppose C is not concurrent lines. P loski proved that the Milnor number of an isolated singlar point of C is less than or equal to $(d-1)^2-{\lfloor}\frac{d}{2}{\rfloor}$. In this paper, we prove that the Milnor sum of C is also less than or equal to $(d-1)^2-{\lfloor}\frac{d}{2}{\rfloor}$ and the equality holds if and only if C is a P loski curve. Furthermore, we find a bound for the Milnor sum of projective plane curves in terms of GIT.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.234-236
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• 1993

Dielectric properties of low viscous silicone oils have been investigated as a function of frequency and The increase of polymerization degree was attributed to presence of Si-O-Si bonds and their increased dissociation factor. The application of the Clausius-Mosotti equation on the low viscous silicone oils, it has been previously assumed that the oils were dilute solutions of polar molecules. In the silicone oil the Si-o and O-Si bonds give dipole polarization. Simple relations have been found which dipole moment and activation energy as a function of number of Si atoms in the low viscous silicone oils.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.53.2-53.2
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• 2011

A small number of active galactic nuclei are known to exhibit prominent double peak emission profiles indicating the presence of a relativistic accretion disk model. Using a Monte Carlo technique, we compute the linear polarization of a double peaked broad emission line. A Keplerian accretion disk is adopted for the double peak emission line region and the Schwarzschild geometry is assumed in the emission region. Far from the accretion disk where flat Minkowski geometry is appropriate, we place a scattering region in the shape of a spherical shell sliced. We generate a line photon in the accretion disk in an arbitraray direction in the local rest frame and follow the geodesic of the photon until it hits the scattering region. The profile of the polarized flux is mainly determined by the relative location of the scattering region with respect to the emission source. When the scattering region is in the polar direction, the linear degree of polarization also shows a double peak structure. Under a favorable condition we show that up to 1% of linear degree of polarization may be obtained.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.6
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• pp.555-561
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• 2000

The remote field eddy current (RFEC) inspection was performed on the ductile cast iron pipes with nominal outer diameter of 100mm, which were machined with various shapes and sizes of defects. Ductile cast iron pipes which are used as water supply pipe have the non-uniform thickness and asymmetric cross section due to relatively high degree of allowable errors during the manufacturing processes. These characteristics of ductile cast in pipes cause the long range background noises in RFEC signals along the pipe. In this study, tile machined defects in pipes were effectively classified by the moving window average (MWA) method which eliminated the long-range noise. The voltage plane polar plots (VPPP) method was used to quantitatively evaluate the depth and circumferential degree of defects. The VPPP signatures showed that the angle between defect signature and the normalized in-phase component on the VPPP is linear to the depth of defects. The nondestructive RFEC technique proved to be capable of quantitatively evaluating the machined defects of underground water supply pipe.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.145-148
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• 2008

ICESat launched in Jan. 2003 has a capability to monitor polar regions with its inclination of 94 degree. ICESat carries GLAS (Geosciences Laser Altimetry System) to measure Earth's topography in unprecedented accuracy, and thus it can be applied for glacier variation due to recent climate changes. Here we present a new method to estimate velocity structure of Amery Ice-Shelf using ICESat altimtery data. ICESat data shows horizontal displacement of Amery Ice-Shelf, which can be directly used for velocity estimation. This method is expected to extend to other ice-shelves in Antarctica.

• Ocean and Polar Research
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• v.31 no.2
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• pp.213-218
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• 2009

We examined the intracellular antioxidative effects of 20 Arctic seaweed extracts in Raw 264.7 cells. Each seaweed species was subjected to extraction using acetone/dichloromethane and methanol, respectively, after which the extracts were combined and used as the test sample. The antioxidant ability of all 20 seaweeds extracts was evaluated using four different activity tests, including the degree of occurrence of intracellular reactive oxygen species (ROS), $ONOO^-$, and lipid peroxidation in Raw 264.7 cells, as well as the extent of oxidative damage of genomic DNA purified from Raw 264.7 cells. Crude extracts from Monostroma obscurum, Alaria esculnta, Laminaria digitata, Desmarestia aculeata, Chorda filum, Ptilota seriata, Phycidrys rubens, Devaleraea ramentacea and Palmaria palmata exhibited significant scavenging effects on the generation of intracellular ROS. Among them, Monostroma obscurum and Phycidrys rubens significantly inhibited membrane lipid peroxidation and DNA oxidation. Moreover, Phycidrys rubens exhibited scavenging effects on peroxynitrite generated from SIN-1.

• Ocean and Polar Research
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• v.37 no.4
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• pp.327-332
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• 2015

Isotopic compositions of ice and meltwater play a very crucial role in paleoclimate studies based on ice cores and water resources research conducted in alpine hydrogeology. Better understanding of variations in the stable isotopic compositions of water is required since changes from ice to liquid water are gaining more attention due to recent climate change. In this work, a melting experiment was designed and conducted to investigate how the isotopic compositions of ice vary with time by heat sources, such as solar radiation. We conducted the melting experiment for 22 hours. The discharge rate rose to a maximum value after 258 minutes and gradually declined because we fixed the heat source. The isotopic compositions of meltwater increased linearly or to a second degree polynomial. The linear relationship between oxygen and hydrogen has a slope of 6.8, which is less than that of the Global Meteoric Water Line (8) and higher than a theoretical value (6.3). The deuterium excess decreased when ${\delta}D$ or ${\delta}^{18}O$ increases or vise versa since the slope of the relationship for ice-liquid exchange is less than 8. These findings and the apparatus of the melting experiments will make a helpful contribution to the studies of stable isotopes and the melting process in temperate and polar regions.