• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2000년도 추계 학술발표회 논문집
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• pp.101-104
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• 2000

1980년대 중반이후 화력발전소용으로 순환유동층 연소로(Circulating fluidized bed combustor : CFBC)가 많이 건설되고 있다. 이는 기존의 고정층 연소로보다 효율면에서 좋고, 차지하는 부피는 훨씬 적기 때문이다. 순환유동층의 층물질로 사용되는 모래, 석탄회, 석회석 등은 순환하는 입도, 비산유출되는 회재(fly ash)와 하부로 배출되는 회재(bottom ash)로 나누어진다. 주입되는 석탄 및 석회석의 입도는 입자-입자, 입자-연소로의 마모(attrition), 입자의 깨짐(fragmentation), 입자의 축소(shrinking) 등에 의해서 변화하게 된다.(중략)

• Journal of applied mathematics & informatics
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• 제41권1호
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• pp.181-192
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• 2023

This work deals with the numerical modeling of dam-break flow over erodible bed. The mathematical model consists of the shallow water equations, the transport diffusion and the bed morphology change equations. The system is solved by central upwind scheme. The obtained results of the resolution of dam-beak problem is presented in order to show the performance of the numerical scheme. Also a comparison of central upwind and Roe schemes is presented.

• 한국환경복원기술학회지
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• 제6권1호
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• pp.51-56
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• 2003

The urban stream include the channel and its adjacent banks, or hillslopes and it consists of various landscape elements. The riparian ecosystem is important to people. Its water is extracted for irrigation and drinking supplies. Biodiversity and many wetland species are protected here. The riparian ecosystem is diverse and needs to be preserved well. So, it is necessary to measure the features of the urban stream accurately to figure out the change of the riparian ecosystem. However, the traditional Electronic Distance Measurement(EDM) surveying is difficult to measure the curvilinear features of the stream - e, g, angle, curve. The beacon Differential Global Positioning System(DGPS) can handle to measure the curvilinear shape. Therefore, the purpose of this study is to measure the change of the river bed in urban stream accurately using realtime beacon DGPS, and ultimately to provide the basic data for identifying the change of the river ecosystem.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.1335-1339
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• 2004

A hydro-geomorphologic change in a sand bed channel reach and vegetation expansion by changes in the How regime is analyzed in this study. Field and aerial photo surveys, basic hydrological analysis about flow regime change due to two dams, Andong Dam and Imha Dam, on the upstream river and computer modeling are conducted. Two Dams in the study reach have obviously affected downstream channel in many ways including the bed particle coarsening, vegetation expansion on the sandbars and following river channel braiding. The phenomenon of no vegetation on the large point bar in front of Hahwe Village seems due to disturbance of the sandbar surface probably due to the cross flow in the meander reach during the flood. Another reason for no vegetation is that the sandbar on this reach has lower subsurface water lovels, as compared with the others in the up- and downstream of the reach where vegetation expanded, which would hinder vegetation from germinating and growing on the sandbar.

• 환경영향평가
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• 제6권1호
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• pp.55-66
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• 1997

This study summarizes the use of satellite data to detect the change of southwestern coastal wetlands in Korea. The images used for this study were two Landsat Thematic Mapper(TM) images (June 12, 1984 & June 2, 1992). TM images were used to classify such different types of wetlands as aquatic bed, nonaquatic bed and other land use in the region. Then it, was possible to a) determine the status of wetlands using image classification products, and b) detect the changes of various types of wetlands influenced by both human and nature. The results from spatiotemporal analysis showed that approximately 120 lad of coastal wetlands were lost from the year of 1984 to 1992. 71 % of the lost wetlands were converted to the reclaimed land. This loss of wetlands has been causing the profound environmental impacts. It has been successfully proved that satellite data are very effective for spatiatemporal change analysis, especially for that of coastal wetlands.

• 한국기계가공학회지
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• 제20권2호
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• pp.38-44
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• 2021

To cater to the transition from single-color to multicolor/multi-material printing, this paper proposes a cartridge-replacing type multi-nozzle Fused Depositon Modeling(FDM) three-dimensional (3D) printer. In the test printing run, tool change failure/wobble/layer shift occurred. It was confirmed that improper support was the cause of this tool change failure. As a solution, spline and electromagnetic cartridges were designed. Wobble was caused by machine vibration and the motor stepping out. To minimize wobble, an additional Z-axis was installed, and the four-point bed leveling method was used instead of the three-point bed leveling method. The occurrence of layer shift was ascribed to the eccentricity of the Z-axis lead screw. Therefore, slit coupler was replaced with an Oldham type. In addition to the mechanical supplementation, the control environment was integrated to prevent accidents and signal errors due to wire connections. Before the final test printing run, a rectifier circuit was added to the motor to secure precise control stability. The final test printing run confirmed that the wobble/layer shift phenomenon was minimized, and the maximum error between layers was reduced to 0.05.

• 한국농공학회논문집
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• 제49권2호
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• pp.17-24
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• 2007

This study analyzes the flood inundation in low agricultural area caused by rainfall during typhoon periods and how flood inundation areas should be affected. GIS techniques, HEC-HMS and HEC-GeoHMS were used for flood runoff, HEC-RAS was applied in water surface elevation analysis at each cross-section. RMA2, SED2D were applied for runoff characteristics of inundation areas and river bed change and distribution of sediment. As a result, velocity distribution was analyzed 2.6 m/s-3.4 m/s in flood inundation by water level increase. In the case of bed elevation change, most sediments were deposited to the parts that adjoin bank.

• 상하수도학회지
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• 제29권6호
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• pp.617-623
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• 2015

In this study, determination methods of monitoring location in water distribution system were suggested and applied to real test bed. Small block of Gwangtan water distribution system is consisted of 582 pipes, 564 junctions, 1 reservoir, and 1 pump station. Small block of Ho Chi Minh water distribution system is consisted of 162 pipes, 148 junctions, and 1 reservoir. Two small block water distribution systems were analyzed by pressure contribution analysis method to determine the optimum monitoring locations. The pressure change was estimated at each junctions by the additional demand at a junction. From the results, the optimum monitoring location can be determined by rank of pressure contribution index at each junctions due to demand change at a junction.

• 상하수도학회지
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• 제11권3호
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• pp.105-111
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• 1997

Taken from the entrance of Juam Dam to 11km long as survey, this study predicted the bed change according to the movement of sediment in jet flow zone. The result of applying compound model and jet model turned out to be satisfactory, though the latter was the better. The jet constant of Juam Dam could be controlled between 0.5 and 0.65. In the jet flow zone of the dam, the prediction of the bed change by the numerical motel showed almost the same to the observed data.

• 한국수자원학회논문집
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• 제37권5호
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• pp.387-395
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• 2004

본 논문에서는 하상변동 및 유사입자의 시간적 공간적 분포를 동시에 모의할 수 있는 2차원 수치모형을 제시하였다. 사행수로의 하상변동은 만곡부의 외측에서는 하상이 세굴되고 훨씬 더 거친 입경의 재료로 구성되며, 만곡부의 내측에서는 하상이 상승하고, 세립토로 구성되었다. 또한 사행하천에서 흐름의 방향에 대한 입자분포 과정은 상류의 변곡점에서 시작하여, 하류 변곡점에서 마치게 되는 것을 보여주었다. 하천의 경계가 불규칙하고 복잡한 하천에서는 혼합사호 형성된 하천에서보다 균일사로 이루어진 하천에서 하상이 깊게 세굴되는 현상을 보여준다. 혼합사로 이루어진 하천에서의 공간적 입도 분포는 사행하천에서와 마찬가지로 하상이 퇴적되는 사행의 내측에서는 세립토로 구성되고 하상이 세굴되는 외측에서는 굵은 입자로 구성되는 것을 보여주었으며, 하천 폭이 좁은 부분에서는 하상의 세출 및 하상재료가 굵게 변화되는 것을 보여주었다.