• Korean Journal of Mathematics
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• v.6 no.2
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• pp.303-311
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• 1998

We study the conformally flat unit vector bundle $E_1$ of constant scalar curvature for the bundle ${\pi}:E^{n+2}{\rightarrow}M^n$ over an Einstein manifold M.

• Honam Mathematical Journal
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• v.38 no.1
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• pp.59-69
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• 2016

We classify conformally flat Kenmotsu 3-manifolds and classify conformally flat cosympletic 3-manifolds.

• Journal of the Korean Mathematical Society
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• v.32 no.3
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• pp.519-529
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• 1995

Let M be a compact smooth manifold of dimension n and let E be a flat (complet) vector bundle over M of rank r.

• Bulletin of the Korean Mathematical Society
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• v.53 no.6
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• pp.1879-1886
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• 2016

In this paper, we investigate domains having a flat piece in the boundary and find a sufficient condition for such a domain to be a cone.

• Communications of the Korean Mathematical Society
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• v.11 no.2
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• pp.391-405
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• 1996

In this article, we calculate the cohomology groups of flat vector bundles on some manifolds.

• Communications of the Korean Mathematical Society
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• v.15 no.3
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• pp.541-547
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• 2000

In this paper, we discuss various limit sets of projectively flat manifolds and relationship between them.

• Journal of the Korean Society of Costume
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• v.66 no.3
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• pp.1-17
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• 2016

This study examined and analyzed the women's jeogoris in the Seoul Gwangjang Market and Busan Jin Market. They study explored the items to look into the current state of the Jeogori patterns, as well as investigate the flat pattern jeogoris, including its source and aspects of change. Korean women's body figure has become more westernized, and the purpose of this study is to investigate the effects of this change on the traditional jeogoris. We hope to gather valuable data, which can be used to propose a new direction for designing hanbok in the future. The study methods are as follows: First, the types of jeogori patterns were examined. Second, the current state of jeogori patterns in the Seoul Gwangjang market and Jin market in Busan were analyzed to look into how the patterns have transitioned. And lastly, the reason for the origination of the flat pattern jeogori and the type of changes will be examined. Current study results show that two pattern types are being used: the flat composition jeogori and the flat pattern jeogori. Surveys show that more than 90 percent of the jeogoris in the Seoul Gwangjang Market are of the flat composition pattern variety, while more than 90 percent of jeogoris in the Busan Jin Market are of the flat pattern variety. In 1998, western-style dress designers in Busan introduced the flat pattern jeogoris, which were used to get rid of the wrinkles caused by the extra space, into the market after the financial crisis period in Korea, as a way to revitalize the market. This new pattern was popular among tea aficionados and traditional Korean musicians. It was exposed to the public via different mediums, such as TV programs, magazines, and brochures. Busan was the first to be exposed, and then it spread to Seoul. It also seems that the reduction of production cost caused the increase of the flat pattern jeogori.

• Journal of Wetlands Research
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• v.14 no.3
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• pp.375-384
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• 2012

The sedimentary processes of the Ganghwa tidal flat has been changed over 20 years because of the large-scale construction projects. The sedimentary environment of the Donggum tidal flat, located in the eastern part of Ganghwa tidal flat and in the lower reaches of Yeomha channel, was affected by changes the tidal current regime and estuarine circulation. These resulted an occurrence of rapid deposition in the tidal flat. The silt-clay laminated silt facies in the upper parts of two core sediments suggested that deposition had been relatively high in the tidal flat. The sedimentation rates from the cores using $^{210}Pb$ analysis were 3.25cm/year(st. 3) and 3.47cm/year(st. 5). However the short-term sediment accumulation rates from 2010 to 2012 were mostly less than 1cm/year, indicated that the sediments deposited relatively low rates. As a result, the sediment in the Donggum tidal flat rapidly accumulated during 2000s due to constructions of man-made structures. Recently, the increase of elevation in the tidal flat resulted to show relatively low sedimentation rate with seasonal variations.

• Journal of Ocean Engineering and Technology
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• v.21 no.2 s.75
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• pp.42-49
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• 2007

It has been known that shallow-water regions, such as tidal flats, sea grass and sea weed beds have water purification capability, and they also serve as nursery grounds for many fishes. On the other hand, tidal flat areas are economically attractive sites for reclamation, to be used for developing industries. When developing shallow-water areas, we have to propose a plan to mitigate the environmental impact associated with such a development plan. However, it is difficult to estimate the affects on the ecosystem and water purification, and the literature related to this matter is insufficient. In order to evaluate the ability of coastal tidal flat and to predict the future changes, it is necessary to develop a reliable prediction technique and construction of data by using a field investigation. In this study, we carried out a numerical model test for the tidal flat ecosystem, using the pelagic system and the benthic system, simultaneously, in order to show a change in the tidal flat ecosystem. The flow of nitrogen, phosphorus and carbon has been identified as a primary consideration of marine ecosystem components, and the capability of water purification and the change of the tidal flat were predicted using this flow. In order to make a more reliable prediction, a field investigation to determine tide, current and creatures of the object coastal area has been done. The purification capability of this shallow-water region is estimated from the model results. According to the results of experiments, the tidal flat has a capability of water purification (Sink) of 11mgN/m2/day, but the other area has a load (Source) of 20mgN/m2/day. As a result, we could confirm that the tidal flat of an object coastal area plays an important role in water purification.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.669-676
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• 2016

A field study was conducted to determine the runoff loss of N and P in small scale of red pepper field plots (10% slope), consisting of three different plots with black polyethylene vinyl mulching (mulching), ridge without mulching (ridge), and flat without ridge and mulching (flat). Composted manure and urea as a basal application were applied at rates of $20MT\;ha^{-1}$ and $93kg\;N\;ha^{-1}$, respectively. Urea at $189kg\;N\;ha^{-1}$ and fused phosphate at $67kg\;P_2O_5\;ha^{-1}$ were additionally applied on June 25 with different fertilization methods, broadcast application in flat plot and hole injection in ridge and mulching plots. Plant uptake of N and P was positively correlated with their respective concentrations in surface soil: mulching > ridge > flat plots. The runoff loss by soil erosion was higher in flat plot than ridge and mulching plot with contour line. Nitrate loss by the runoff water had no significant differences among three surface management practices, but the higher average value in ridge and mulching plots than flat plot. Especially, the flat plot had no phosphate loss during summer season. This is probably due to low labile P content in surface soil of flat plot. In the summation of soil and water loss, flat plot was higher in N and P loss than ridge and mulching plot with contour line. Nevertheless, the nitrate and phosphate loss by runoff water could be more important for non-point source management because the water could meet the river easier than eroded soil because of re-deposition around slope land.