• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.233-233
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• 2019

본 연구에서는 3형식 다공성 인공어초의 국부세굴 발생에 따른 인공어초의 안정성 검토를 위하여 3차원 수치모형인 FLOW-3D의 Sediment 모듈을 적용하여 분석을 실시하였다. 실험파랑 설정을 위하여 인공어초 설치 예정지인 서해 대상해역(대청도, 연평도 인근)의 100년 빈도 설계파랑을 적용하였으며, Bretschneider-Mitsuyasu 스펙트럼 기법을 통하여 파랑을 재현하였다. 원형상격자 조건은 최대 0.1m~2.0m에 해당하며, 수치모형실험 해석 시간을 고려하여 입사파랑의 진행방향으로 인공어초의 1/2 폭에 해당하는 X축(190개), Y축(80개), Z축(110~180개) 영역에 대한 격자조건 설정하고 분석을 실시하였다. 분석은 인공어초 하중에 따른 동적 거동을 반영하는 FSI(Flood Structure Interaction)기법을 적용하였으며, 분석결과 인공어초 구조물 하단의 돌출부분에서 세굴발생이 확인되었으며, 최대세굴심은 3형식 인공어초의 규격 및 단위체적당 중량이 클수록 높게 발생하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제34권1호
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• pp.177-182
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• 2010

인공어초의 구조적 설치로 인하여 흐름의 변화가 생기며, 이로 인한 인공어초 주변의 퇴적물 수송은 침전과 매몰뿐만 아니라 저질 환경에도 영향을 미친다. 본 조사는 경상북도 포항시 해역에 시설된 사각형 어초의 시설상태를 파악하기 위하여 수중음향 영상기기인 사이드 스캔 소나(SSS), 인공위성 위치 측정기(DGPS)와 잠수조사를 통한 조사를 실시하였다. 조사 결과, 총 139개소에서 10,526개의 사각형 어초가 발견되었으며, 어초 기능 유지에 영향을 미치는 수준으로 판단되는 0.5m 이상의 매몰과 세굴은 각각 4개소(0.5~1.2m, 2.9%)와 3개소(0.5m, 2.2%)로 나타났다. 파손의 경우 10,526개의 발견된 사각형 어초 중 183개(1.74%)로 나타났다. 따라서 포항시 해역에 시설된 사각형 인공어초의 시설상태는 비교적 안정적인 것으로 나타났다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.46-46
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• 2011

Severe sediment erosion during floods occur disaster and economic losses, but general sediment erosion is basic mechanism to move sediment from upstream to downstream river. In addition, it is important process to change river form. Check dam, which is constructed in mountain stream, play a vital role such as control of sudden debris flow, but it has negative aspects to river ecosystem. Now a day, check dam of open type is an alternative plan to recover river biological diversity and ecosystem through sediment transport while maintaining the function of disaster control. The purpose of this paper is to verify sediment erosion progress of river bottom and bank as first step for river restoration after dam slit by cross-sectional shear stress and critical shear stress. Study area is upstream reach of slit check dam in mountain stream, named Wasada, in Japan. The check dam was slit with two passages in August, 2010. The transects were surveyed for four upstream cross-sections, 7.4 m, 34 m, 86 m, and 150 m distance from dam in October 2010. Sediment size was surveyed at river bottom and bank. Sediment of cobble size was found at the wetted bottom, and small size particles of sand to medium gravel composed river bank. Discharge was $2.5\;m^3/s$ and bottom slope was 0.027 m/m. Excess shear stress (${\tau}_{ex}$) was calculated for hydraulic erosion by subtracting the values of critical shear stress (${\tau}_{c}$) from the value of shear stress (${\tau}$) at river bottom and bank (${\tau}_{ex}=\tau-{\tau}_c$). Shear stress of river bottom (${\tau}_{bottom}$) was calculated using the cross-sectional shear stress, and bank shear stress (${\tau}_{bank}$) was calculated from the method of Flintham and Carling (1988). $${\tau}_{bank}={\tau}^*SF_{bank}((B+P_{bed})/(2^*P_{bank}))$$ where $SF_{bank}=1.77(P_{bed}/p_{bank}+1.5)^{-1.4}$, B is the water surface width, $P_{bed}$ and $P_{bank}$ are wetted parameter of the bed and bank. Estimated values for ${\tau}_{bottom}$ for a flow of $2.5\;m^3/s$ were lower as 25.0 (7.5 m cross-section), 25.7 (34 m), 21.3 (86 m) and 19.8 (150 m), in N/$m^2$, than critical shear stress (${\tau}_c=62.1\;N/m^2$) with cobble of 64 mm. The values were insufficient to erode cobble sediment. In contrast, even if the values of ${\tau}_{bank}$ were lower than the values for ${\tau}_{bottom}$ as 18.7 (7.5 m), 19.3 (34 m), 16.1 (86 m) and 14.7 (150 m), in N/$m^2$, excess shear stresses were calculated at the three cross-sections of 7.5 m, 34 m, and 86 m distances compare with ${\tau}_c$ is 15.5 N/$m^2$ of 16mm gravel. Bank shear stresses were sufficient for erosion of the medium gravel to sand. Therefore there is potential to erode lateral bank than downward erosion in a flow of $2.5\;m^3/s$. Undercutting of the wetted bank can causes bank scour or collapse, therefore this channel has potential to become wider at the same time. This research is about a potential of sediment erosion, and the result could not verify with real data. Therefore it need next step for verification. In addition an erosion mechanism for river restoration is not simple because discharge distribution is variable by snow-melting or rainy season, and a function for disaster control will recover by big precipitation event. Therefore it needs to consider the relationship between continuous discharge change and sediment erosion.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.718-722
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• 2009

하도 상황이 수역(水域)에서 식생역(植生域)으로 변화하여 최종적으로 육역화(陸域化)단계로의 천이가 진행되는 현상을 하도 육역화라고 한다. 하도 육역화는 하천의 생태환경적 측면에서 많은 문제들을 야기할 수 있으며, 단일 단면 하도의 복단면 고착화로 하천 통수 단면이 감소하여 하도의 홍수 관리 기능에 심각한 위해 요소로 작용할 수 있다. 본 연구는 하도 육역화 방지를 위한 수공구조물로서 말뚝을 설치하고 그 효과를 3차원 수치모형인 FLOW-3D를 이용하여 검토하였다. 수치 모의는 구조물 주변의 복잡한 흐름 모의를 위하여 복잡한 지형지물이 있는 경우에 많이 활용되는 LES(Large Eddy Simulation) 난류 모델을 적용하였으며 세굴 및 퇴적 영향을 알아보기 위하여 유사 세굴(Sediment Scour) 모델을 적용하였다. 하도 육역화 방지 수공구조물의 효과 검토를 위하여 모형 수로의 제방 근처에 말뚝을 설치하고 말뚝직경, 설치 간격 및 배열 등을 변화시켜 구조물 주변의 동수역학적 거동, 흐름분리 효과 및 세굴영향을 수치모의를 통하여 분석하였다. 분석 결과 말뚝에 의한 흐름 분리와 국부 세굴에 의하여 하상 퇴적이 상대적으로 감소되는 효과를 나타냈으며 설치간격이 수변으로부터 말뚝 두께의 2배 그리고 흐름방향으로 말뚝 두께의 2배 이내의 간격으로 설치하여야 더욱 효과적인 것으로 나타났다. 추후 다양한 수리모형 실험을 통한 검증과 다양한 조건에 대한 수치 모의를 통하여 하도 육역화 방지 기술을 개발할 수 있을 것으로 사료된다.

• 한국환경과학회지
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• 제9권1호
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• pp.49-55
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• 2000

An EMERGY analysis of the main energy flows driving the economy of humans and life support systems consists of environmental energies, fuels, and imports, all expresses as solar emjoules. Total EMERGY use(720.0 E20 sej/yr) of the Nakdong River Basin is 96 per cent from imported sources, fuels and goods and services. EMERGY flows from the environment such as rain and geological uplift flux accounted for only 4 percent of total EMERGY use. Consequently, the ratio of outside investment to attracting natural resources was large, like other industrialized areas. EMERGY use per person in the Nakdong River Basin indicates a moderate EMERGY standard of living, even though the indigenous resources are very poor. Population of 6.66 million people in 1996 is already in excess of carrying capacity of the basin. Carrying capacity for steady state based on its renewable sources in only 0.226 million people. EMERGY yield ratio and environment loading ratio were 1.07 and 28.52, respectively. EMERGY sustainability index, a ratio of EMERGY yield ratio to environment loading ratio, is therefore less than one, which is indicative of highly developed consumer oriented economies. This study suggests that the economic structure of the Nakdong River Basin should be transformed from the present industrial structure to the social-economic structure based on an ecological-recycling concept for the sustainable use of the Nakdong River.

• 한국수자원학회논문집
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• 제30권4호
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• pp.401-409
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• 1997

본 연구는 하천 및 저수지의 하상변동을 예측하기 위하여 하천을 단일 수로로 취급하였으며 저수지는 몇 개의 수로로 나누어 유량의 합성모형, 2차원 분류모형 및 1차원 밀도류모형을 이용하였다. 수치모형은 유량의 연속방정식과 운동량방정식을 double-sweep method로 유량과 수위의 변동량을 구한 후, 수위 및 유량의 변동량을 유사의 연속방정식에 적용하여 하상의 세굴 및 퇴적으로 인한 하상고의 변동량을 예측하였다. 본 연구대상 구역은 보성강댐에서 주암댐의 상류지역인 문덕교까지 약 31km구간을 선정하였으며 하천이 약 13km, 저수지 부분이 약 18km이다.

• 한국물환경학회지
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• 제22권1호
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• pp.150-158
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• 2006

Over the past few years, many studies have been conducted on the flow, sediment movement, pollution transportation and scour etc. However, very few attempts have been made at the hydraulic studies reflecting upon the ecological function. The objective of this study is to examine the structures of the flow and turbulence in an open circular channel and their relationship to distribution of the organisms and chironomids. Under different flow conditions, the organic matter and some chironomids were injected into the channel. Using the obtained velocity data, the flow mechanisms and the turbulent shear stresses were analyzed. Organic matters and chironomids were distributed on the region that the velocity was slower and the turbulent shear stresses were smaller. Some habitat moved even though chironomids were inhabited. This phenomenon has relationship with the flow mechanism. Some chironomids have distributed around the habitat structure of a hemisphere. The secondary flow has affected the deposition of the organic matters and the distribution of chironomids.

• 한국해양공학회지
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• 제20권3호
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• pp.61-66
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• 2006

The estuary has a very complex coastline and bottom topography. Before the close of floodgate, the Keum river estuary was deposited with sediment from the Keum river, created bythe construction of the Keum river estuary dike. So, a periodical dredging is necessary to assure water depth for boat entry and departure to Kunsan port. Theof this study is to find the change of tidal current of M2tide and the topography before and after construction at the Geum River estuary dike. The change of water depth is investigated by digitizing the sea map (No.305) of Kunsan port, which was edited by National Oceanographic Research Institute. The calculated co-range and co-tidal charts of M2tide before the dike construction are similar to the observed ones. Therefore, the amplitude and phase after construction at Geum River estuary dike increases compared to before construction at Geum River estuary dike. The scour occurred in the A-A' section.

• Ocean and Polar Research
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• 제33권3호
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• pp.265-280
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• 2011

The temporal dynamics of the meiofauna community in Marian Cove, King George Island, Antarctica were observed from March 7 to December 21 2007. Nine meiofauna taxa were found, with nematodes the most dominant group, making up 92.97% of the total meiofauna density, followed by harpacticoid copepods (3.18%). Meiofauna abundance ranged from 123 to 874 individuals per 10 $cm^2$ (mean 464 inds.10 $cm^{-2}$), which is lower than that found in some polar and temperate regions. The lowest meiofauna abundance was found in the 26th April sample (III) and the highest meiofauna abundance was found in the March 23rd sample (II). There was no correlation between meiofauna abundance and season. The seasonal changes were likely caused by meltwater runoff, and there were the physical disturbances on the bottom sediment by huge iceberg. Biomass of meiofauna varied between 20.36 and 101.02 ${\mu}gC{\cdot}10\;cm^{-2}$, and overall mean biomass was 54.17 ${\mu}gC{\cdot}10\;cm^{-2}$ during the study periods. More than 80% of meiofauna was concentrated in the upper 2 cm of the sediment, and density decreased with depth. The mean diversity index was 0.37, and the ratio between the abundance of nematodes: and harpacticoids (N/C) ratio ranged from 7.31 to 95.04 (mean 26.39). NMDS analysis divided the community into three groups: A (III, IV, V, VII, VIII), B (II, IX, XI, XII) and C (I, V, X). The results of ANOSIM and SIMPER analysis revealed significant differences in community structure among three groups and major contributed meiofauna taxon in grouping were nematodes and copepods. No significant correlations were observed between major meiofauna taxon and environmental factors. Thirteen species in 12 genera representing nine families of harpacicoids were recorded. Ancorabolidae was the most diverse family, and Heteropsyllidae was the most abundant. The correlation analysis between benthic harpacticoid copepods and environmental factors showed that some species were affected by water temperature, sediment temperature, salinity, chlorophyll a concentration, grain size of the sediments and heavy metal contents of the sediments. These data describe the usefulness of benthic harpacticoid copepods as biological indicator species in Antarctic regions.

• 한국해안·해양공학회논문집
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• 제31권6호
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• pp.423-433
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• 2019

서남해에서 해상풍력구조물의 건설에 따른 해저지형변화를 예측하기 위하여, 조석, 조류, 부유사 그리고 해저질 등에 대한 현장조사를 수행하였고, 이들 자료를 수치실험에 활용될 수 있도록 하였다. 수치실험에서 표사량 산정은 관련 상수를 시행착오적으로 변화시켜 관측된 부유사농도에 대해 계산치의 오차가 적당할 때에 경험상수들을 결정하는 방법을 사용하였는데, 어떤 농도분포인자가 0.1 그리고 부유사 평형농도 공식의 비례상수가 0.05일 때, 관측치와 계산치가 합리적으로 유사하였다. 부유사농도에 관한 개경계조건은 관측된 부유사농도에 대해 남동측 경계점에서 11.0배, 남서측 경계점에서 0.5배, 서북측 경계점에서 1.0배, 북서측 경계점에서 1.0배 그리고 북동측 경계점에서 1.0배이었을 때, 개경계와 서로 인접한 계산영역 내의 수심변화 계산결과가 단속적이지 않고 매끄럽게 나타났다. 그리고 연간침식퇴적량은 해상풍력 구조물의 건설전후에 대하여 그 변화가 ± 1 cm 이상 발생하는 해역은 거의 나타나지 않았는데, 사용된 대격자 수치모형은 세굴과 같은 국지적 현상을 재현할 수 없고, 해상풍력 하부구조물이 직경 1 m 정도의 자켓타입의 투과식이어서 이들에 의하여 ± 2 cm/s 이상의 유의미한 유속변화역이 거의 나타나지 않았기 때문에, 해저지형변화가 미미한 것은 당연한 결과인 것으로 판단되었다.