• Journal of Environmental Impact Assessment
• /
• v.23 no.2
• /
• pp.150-156
• /
• 2014

The aim of this study is to detection of changed vegetation area of Saemangeum tidal flat with comparison of topography and surface sediments during the dyke construction. Sedimentary facies of four seasons of 2001 from inside Saemangeum tidal flat revealed homogeneous layers in the upper part, however near sea side tidal flat were detecting with carried out rapid sediment deposition during the dyke construction using satellite image spatial analysis. The sedimentation types inside Saemangeum tidal flat were classified with vegetation types, which were well matched with the sedimentation pattern revealed by change in vegetation patterns.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.05b
• /
• pp.155-158
• /
• 2005

수자원 분야에서 DEM은 유역을 분할하고 하천망을 생성하며 유역 범위 내에서 지형인자를 계산하는 과정에서 광범위하게 이용되고 있다. 그러나 수치지도의 등고선이나 영상으로부터 추출된 DEM은 sink나 flat area와 같은 오류를 다수 포함하고 있으며, 이러한 오류들을 합리적인 방법으로 제거하는 과정이 필요하다. 본 연구에서는 DEM에서의 sink를 제거하기 위하여 breaching 알고리즘(Grabercht와 Martz, 1996)을 포함하는 filling method(Jenson과 Domingue, 1988; Martz와 Jong, 1988)를 이용하였으며, flat area를 처리하기 위해서는 combined gradient method(Grabercht와 Martz, 1996)를 이용하였다. 또한 흐름방향을 결정하기 위해서는 8방향법(O'Callaghan과 Mark, 1984)을 이용하였다. 이러한 방법을 통하여 보정된 DEM을 이용하여 흐름방향과 흐름누적수를 계산한 후 하천망을 추출하였다. 추출된 하천망은 ArcView 3.2a와 TOPAZ v3.1을 적용한 WMS v6.1에서의 결과와 비교하였으며, DEM의 오류수정을 위한 알고리즘이 적절히 구현된 것을 확인 할 수 있었다. 따라서 본 연구에서 개발한 DEM 보정기술은 DEM을 수자원 분야에 이용하기 위해 필요한 sink와 flat area 처리를 효과적으로 수행할 수 있는 것으로 나타났다.

• The Korean Journal of Malacology
• /
• v.32 no.1
• /
• pp.31-36
• /
• 2016

In the present study, we observed a unique association of the flat oyster, Ostrea denselamellosa obtained from a muddy substrate at Haechang Bay, the south coast of Korea in the spring of 2013. Fossilized or semi-fossilized veneriid clam shells, possibly Ruditapes philippinarum, were found adhering to the umbonal area of the flat oyster valves. This unique association of the flat oyster shells with the fossilized clam shells suggested that the flat oyster larvae utilized the clam shells as substrate during settlement. Since availability of clam shells in the muddy subtidal environment is limited, this unique substrata for the flat oyster larvae may limit recruitment of the flat oysters in the bay.

• Honam Mathematical Journal
• /
• v.41 no.4
• /
• pp.799-812
• /
• 2019

We introduce flat e-covers of modules and define e-perfect rings as a generalization of perfect rings. We prove that a ring is right perfect if and only if it is semilocal and right e-perfect which generalizes a result due to N. Ding and J. Chen. Moreover, in the light of the fact that a ring R is right perfect if and only if flat covers of any R-module are projective covers, we study on the rings over which flat covers of modules are (generalized) locally projective covers, and obtain some characterizations of (semi) perfect, A-perfect and B-perfect rings.

• Journal of Magnetics
• /
• v.17 no.1
• /
• pp.56-60
• /
• 2012

This paper presents an analysis and experiment of the flat coil actuator with shorted turn. The flat coil actuator is widely used in high precision products because it has no friction between the moving coil and the guide. A shorted turn and a center pole are placed into the flat coil actuator in order to reduce the inductance of the coil and improve the initial response when the actuator is voltage-driven. Enhanced dynamic performance of the flat coil actuator with shorted turn was demonstrated by simulation and experiment.

• Journal of the Korea Concrete Institute
• /
• v.12 no.5
• /
• pp.153-164
• /
• 2000

Numerical studies were carried out to investigate long-term behavior of flat plates, subjected to combined in-plane compressive and transverse loads. For the numerical studies, a computer program of nonlinear finite element analysis was developed. It can address creep and shrinkage as weel as geometrical and material nonlinearity, and also it can address various load combinations and loading sequences of transverse load, in-plane compressive load and time. This numerical method was verified by comparison with the existing experiments. Parametric studies were performed to investigate the strength variations of flat plates with four parameters; 1) loading sequence of floor load, compressive load and time 2) uniaxial and biaxial compression 3) the ratio of dead to live load 4) span length. Through the numerical studies, the behavioral characteristics of the flat plates and the governing load combinations were examined. These results will be used to develop a design procedure for the long-term behavior of flat plates in the future.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2006.11a
• /
• pp.257-260
• /
• 2006

West coast of Korea belongs to the five largest tidal-flat zones in the world. Aiming at the efficient management and preservation of the eco-system and the enhancement of the bio-productivity of the tidal-flat zones, development of a environment-friendly vehicle for tidal-flat area is being attempted. This paper deals with the description of the characteristics of the tidal-flat zones of west coast of Korea, the technology assessment of the related products in the ATV(All-Terrain Vehicle) market, the demand assessment for the resident people.

• Journal of the Korean Mathematical Society
• /
• v.36 no.4
• /
• pp.747-756
• /
• 1999

In ring theory it is well-known that a ring R is (von Neumann) regular if and only if all right R-modules are flat. But the analogous statement for this result does not hold for a monoid S. Hence, in sense of S-acts, Liu (]10]) showed that, as a weak analogue of this result, a monoid S is regular if and only if all left S-acts satisfying condition (E) ([6]) are flat. Moreover, Bulmann-Fleming ([6]) showed that x is a regular element of a monoid S iff the cyclic right S-act S/p(x, x2) is flat. In this paper, we show that the analogue of this result can be held for automata and them characterize regular semigroups by flat automata.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.46 no.2
• /
• pp.49-57
• /
• 2004

Generally, the properties of aggregate greatly affect the physical and mechanical properties of concrete. Flat and elongated particles in coarse aggregates, for some construction uses, may interfere with consolidation and be difficult to place. In this study, an experiment to evaluate properties of flat and elongated particles as coarse aggregate in concrete was conducted. The experiments include slump test, air content test and compressive strength test. The test result of slump and change of slump was rapidly decreased by percentage of flat and elongated particles. But it had not a trend by increasing percentage of flat and elongated particles. Compressive strength of hardened concrete does not make any differences in comparison.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.9 no.2
• /
• pp.69-76
• /
• 2001

The purpose of this research is to investigate the thermal performance of embossing surface sandwich panel and flat surface sandwich panel. To do this research, thermal performances in summer season at the six points of embossing surface sandwich panel and flat surface sandwich panel are investigated focusing on the temperature. Three kinds of embossing surface sandwich panel and one kind of flat surface sandwich panel are used for this research. At the same size of sandwich panel, the average temperature differences of flat surface sandwich panel between average temperature at the 0.5 mm below copper plate and average outside air temperature and surface temperature are higher than those of embossing surface sandwich panel. The average heat transfer rate of flat surface sandwich panel in higher than that of embossing surface sandwich panel. More study will be needed about the size of diameter and height of embossing, and materials of embossing surface sandwich panel.