• Bulletin of the Korean Mathematical Society
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• v.52 no.4
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• pp.1139-1148
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• 2015

For any alternating knot, it is known that the double branched cover of the 3-sphere branched over the knot is an L-space. We show that the three-fold cyclic branched cover is also an L-space for any genus one alternating knot.

• Bulletin of the Korean Mathematical Society
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• v.54 no.5
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• pp.1619-1625
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• 2017

The aim of this short note is to give a simple proof of the non-rationality of the double cover of the three-dimensional projective space branched over a sufficiently general quartic.

• Journal of the Korean Mathematical Society
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• v.43 no.4
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• pp.691-701
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• 2006

In this paper, we construct a new exotic smooth 4-manifold X which is homeomorphic, but not diffeomorphic, to ${\mathbb{C}}\mathbb{P}^2{\sharp}13\overline{\mathbb{C}\mathbb{P}}^2$. Moreover the manifold X has vanishing Seiberg-Witten invariants for all $Spin^c$-structures of X and has no symplectic structure.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.79-82
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• 2002

The addition of switches to a distribution feeder does, in general, increase reliability by decreasing the duration of the outage of many to the customers on the feeder. To cover its service area so that feeder-level delivery reaches sufficiently close to all customers, feeders typically split their routes many times, in what is often called a lateral feeder. It is interesting to note, however, that the effectiveness of a switch is very much dependent on the types of lateral feeder. The types of lateral are classified into two types. The first is loop lateral feeder that can connect its load to an adjacent feeder through a tie line in case that a fault occurs in its feeder and it is laid out so that every feeder has complete fault backup through re-switching of its loads to other sources like a main feeder. The second is the radial lateral feeder cannot connect its load to an adjacent line, no provision is made for contingency backup of feeders. There are no other circuits in the radial lateral feeder form which to restore power. In this study, we evaluate the effectiveness of a switch installation between on the radial and loop lateral feeders to increase reliability by decreasing the duration of the outage. These results can help power utility to design the switch layouts on the radial and loop lateral feeder system.

• Fisheries and Aquatic Sciences
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• v.11 no.3
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• pp.159-165
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• 2008

Intertidal benthic algal communities on the shores of Gujido and Daeyeonpyeongdo islets, Korea, were examined in October 2007. At both sites, 45 seaweeds including 7 green, 6 brown and 32 red algae were identified. The number of species at Gujido(38 species) was 1.5 times higher than at Daeyeonpyeongdo(25 species), but seaweed coverage was very similar with about 20%. Dominant seaweeds in terms of coverage and importance value were Hildenbrandtia sp., Caulacanthus okamurae, Ulva pertusa, and Gelidium amansii at Gujido and U. pertusa, Hildenbrandtia sp., Gelidium divaricatum at Daeyeonpyeongdo. The vertical distribution pattern of the seaweeds was G. divaricatum-U. pertusa, Hildenbrandtia sp.-U. pertusa, Hildenbrandtia sp., Ishige okamurae from upper to lower intertidal zone but seaweed zonations were not observed on the Gujido rocky shore. At both sites, coarsely-branched forms were the dominant functional group in species number and percent cover(among benthic algal species). The rocky shores of the two sites were dominated by crustose coralline and green algae, whose presence generally results in decreased seaweed biodiversity and community stability. Therefore, the shores of the Yeonpyeongdo islets are of considerable environmental concern and should be monitored for seaweed species composition and community structure.

• ALGAE
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• v.28 no.2
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• pp.161-171
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• 2013

A morphologically distinct lineage within the Bostrychia moritziana-B. radicans species complex is described as a new species. Bostrychia anomala has thalli with branched monosiphonous filaments with apical cell divisions. The species has terminal tetrasporangial stichidia, each subtending cell bearing tetrasporangia with 2 cover cells. Discharged spores divide transversely, the lower cell first forming a narrow rhizoid and the upper cell forming a monosiphonous shoot. Females have subterminal procarps and males have terminal spermatangial stichidia. Carposporophytes are spherical. Isolates in culture show a pattern of cell death not associated with injury, reminiscent of programmed cell death. Bostrychia anomola shows cell death at intervals along the filaments resulting in division of adjacent cells on either side of the dead cell re-joining the filament; cell division of only one adjacent cell resulting in branching at that site; or filaments fragmenting at the cell death point with adjacent cells forming new apical cells, a means of thallus propagation. The cell death pattern could be a method of filament propagation in the mangrove environment where sexual reproduction is rare.

• Journal of Korean Society on Water Environment
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• v.24 no.5
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• pp.543-549
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• 2008

Human activities and land-use practices are intensely widening the urban areas. High impervious surface areas cover much of urban landscapes and are the primary pollutant sources which can lead to water quality and habitat degradation in its watershed. As the urban areas expand, transportation land-use such as parking lots, roads, service areas, toll-gates in highways and bridges also increase. These land-uses are significant in urban pollution due to high imperviousness rate and vehicular activities. To regulate the environmental impacts and to improve the water quality of rivers and lakes, the Ministry of Environment (MOE) in Korea developed the Total Pollution Load Management System (TPLMS) program. The main objective is to lead the watershed for a low impact development. On a local scale, some urban land surfaces can be emitting more pollution than others. Consequently, in urban areas, the unit loads are commonly employed to estimate total pollutant loadings emitted from various land-uses including residential, commercial, industrial, transportation, open lands such as parks and golf courses, and other developed land like parking areas as a result of development. In this research, unit pollutant loads derived specifically from transportation land-uses (i.e. branched out from urban areas) will be provided. Monitoring was conducted over 56 storm events at nine monitoring locations during three years. Results for the unit pollutant loads of transportation land-use are determined to be $399.5kg/km^2-day$ for TSS, $12.3kg/km^2-day$ for TN and $2.46kg/km^2-day$ for TP. The values are higher than those of urban areas in Korean MOE and US highways. These results can be used by MOE to separate the pollutant unit load of transportation landuses from urban areas.

• Applied Microscopy
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• v.40 no.2
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• pp.109-116
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• 2010

Morphology and microstructure of the suction trap in aquatic Utricularia japonica were examined using scanning electron microscopy. Branched stems bear numerous suction traps without root formation. The traps are derived axillary from the node, and their antennae and appendages extend in a peculiar fashion. The trap walls are thin, two-celled, parenchyma tissue and simple, small glands are scattered in both internal and external surface of the trap. The entrance of the trap is surrounded by one pair of dorsal antennae and ventral appendages, where the former guides the prey to the entrance. Trap door is situated below the entrance and numerous sessile and stalked capitate trichomes cover the entrance and even on the door surface. The capitate trichomes are secretory, but four trigger hairs formed on the central areas of the door are not. They are believed to function in activating and tripping the trap door. A specialized region of the threshold come in contact with the lower portion of the door upon closing. The secretory capitate trichomes near this region are responsible for producing and secreting a mucilage-like substance which composes the velum. Two-armed bifid glands are located in the interior side of the threshold, while four-armed quadrifid glands are considerably numerous occurring over the entire inner trap wall. Bifid and quadrifid glands develop semi-spherical basal cells that connect them to the inner wall surface. Antennae, trigger hairs, capitate trichomes, bifid and quadrifid glands are more important structures in the carnivory of U. japonica.