• 한국음향학회지
• /
• 제19권3호
• /
• pp.77-85
• /
• 2000

사질퇴적물의 함량이 높은 대한해협 퇴적물에 대해 새로운 음파전달속도 측정 장비(sediment sound velocimeter)를 이용 음파전달속도와 물리적 성질을 측정하여, 연구지역의 지음향 및 물리적 특성을 제시하였다. 연구지역 퇴적물의 물성 및 음파전달속도 변화는 조직의 변화에 의해 크게 좌우되는 것으로 나타났다. 연구결과 음향 및 물성 값을 바탕으로 연구지역을 3개 지역(provinces; mid-shelf, shelf margin and trough)으로 구분할 수 있었으며, 이러한 결과는 탄성파 단면 분석을 통해 시스템 트랙과 퇴적계로 지역구분한 기존의 결과[14]와 잘 일치한다. 연구를 통해 새롭게 제시된 3개 지역의 지음향모델은 Briggs and Fischer[5]가 제시한 기존의 대한해협 지 음향모델의 수정모델로 제시한다.

• 한국농공학회지
• /
• 제40권4호
• /
• pp.85-93
• /
• 1998

In the 2nd year study of a 5 year project to evaluate the soil quality and develop the best management practices for mountaineous soils, 11 runoff plots were treated and monitored with respect to physical property of the soil, runoff and sediment discharge, and the following results were obtained. 1. Bulk density and porosity did not show any siginificant difference between experimental treatments. 2. Runoff was basically dependent on the soil's physical property and tillage. Up-and-down plots showed the highest runoff while contour plots the lowest runoff. 3. Sediment yield in the mountaineous soils was directly related to tillage and residue cover. Residue covered plots showed the lowest sediment yield and up-and-down plots the highest sediment yield. And it is recommended that the best management practices using till_age and residue cover for the mountaineous soils must be developed to protect soil quality and maintain agricultural productivity.

• 한국수산과학회지
• /
• 제31권5호
• /
• pp.609-621
• /
• 1998

1. 연구지역내 sand ridge들은 10$\~$20 m 높이의 비대칭형태이며, 등수심선과 평행하게 발달해 있고, sand ridge의 경사진 부분에서는 지역에 따라 sand wave 형태의 이미지가 나타나는 것으로 보아 현재 다소 활동성이 있는 것으로 보인다. 2. Ridge 주변 위치별 입도, 물리적 성질, 음파전달속도 값은 차이가 크지 않았는데, 이것은 본 연구지역의 주 퇴적상인 사질의 퇴적층이 판의 형태로 넓게 분포하고 있기 때문이다. 3. 코어 하부에는 해수면이 상승하면서 생성된 transgressive sand sheet 퇴적상의 특징을 지시하는 40$\~$200cm 두께의 자갈, 패각편, 조립사가 혼재된 퇴적상이 나타난다. 이들 사질의 분급이 양호하지 않은 이유는 해수면이 상승하면서 조류나 고에너지 환경에서 재동(reworking)되어 퇴적된 palimpsest와 관련된 것으로 사료된다.

• Ocean Systems Engineering
• /
• 제2권4호
• /
• pp.289-295
• /
• 2012

Assume fluid eddy viscosity in the vertical direction is parabolic. Sediment particles diffuse with the given fluid eddy viscosity. However, when the vertical diffusion coefficient profile is computed from the suspended sediment concentration profile, the coefficient shows lager values than the fluid mixing coefficient values. This trend was explained by using two sizes of sediment particles. When fine sediment particles like wash load are added in water column the sediment mixing coefficient looks much larger than the fluid mixing coefficient.

• 한국해안해양공학회지
• /
• 제7권3호
• /
• pp.233-240
• /
• 1995

비정상 이송확산 방정식의 고정도 수치계산법을 이용, 표사이동의 비평형성을 고려하는 항로매몰 예측법을 개발하고, 2차원 이동상 모형실험으로부터 얻어지는 항로매몰형상과 매몰량을 비교 검토함으로써 예측법의 적용성을 확인하였다. 아울러 이 예측법을 현지 scale의 model 항로에 적용, 매몰형상 및 매몰량을 예측함과 더불어 항로경사부에 있어서 복단면을 설치하여 항로내에서의 매몰량을 최소화하는 항로매몰 저감공법에 대하여 검토하였다. 그 결과. 항로경사부에 설치되는 복단면의 형상에 있어서, 복단면의 폭은 비평형상태의 표사이동이 평형상태로 회복됨에 요구되는 최소의 유하거리로서, 복단면의 깊이는 항로주변의 수심과의 비로서 결정되는 것을 알 수 있었다. 그러나 항로경사면에 설치되는 복단면의 폭과 깊이는, 역시 항로주변의 파랑과 흐름 그리고 저질입경 등과 같은 자연조건요인들에 의하여 크게 좌우되는 점을 감안할 때, 항로매몰저감을 목적으로 하는 복단면의 설치계획 및 시공에 앞서 세밀한 현지관측조사와 많은 자료수집 및 분석이 요구된다.

• Environmental Engineering Research
• /
• 제21권1호
• /
• pp.52-57
• /
• 2016

Sediment is a useful natural source but deteriorated continually by anthropogenic and industrial sources. Therefore, it is imperative to search a suitable method for improving or restoring sediment quality. Sediment has been tested to identify the effects of some external agents on a polluted area for 28 days. Chemical analysis and total viable counts (TVC) test have been conducted for 4 days interval to assess their performance. The analyses of chemical oxygen demand (COD), acid volatile sulfide (AVS), total phosphorous (T-P), total nitrogen (T-N) indicate that the chemical agents was more efficient to improve sediment quality whereas the microbial agent was more efficient for nutrient releasing from sediment. Oxygen releasing property of the chemical agent was thought to be providing with more congenial environment for the higher growth of the bacterial community than the direct application of microbial agents.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2016년도 학술발표회
• /
• pp.196-196
• /
• 2016

Landslide dam failure presents as a severe natural disaster due to its adverse impact to people and property. If the landslide dams failed, the discharge of a huge volume of both water and sediment could result in a catastrophic flood in the downstream area. In most of previous studies, breaching process used to be considered as a constructed dam, rather than as a landslide dam. Their erosion rate was assumed to relate to discharge by a sediment transport equation. However, during surface erosion of landslide dam, the sediment transportation regime is greatly dependent on the slope surface and the sediment concentration in the flow. This study aims to accurately simulate the outflow hydrograph caused by landslide dam by overtopping through a 2D surface flow erosion/deposition model. The lateral erosion velocity in this model was presented as a function of the shear stress on the side wall. The simulated results were then compared and it was coherent with the results obtained from the experiments.

• 한국환경과학회지
• /
• 제15권7호
• /
• pp.643-651
• /
• 2006

This study investigated the distributive property of micropollutants in sediment around Gwang-yang bay using simultaneous analytical method of 310 chemicals. In the results, the major micropollutants detected were CH type chemicals such as aliphatic, polycyclic compounds, benzenes, and CHN(O) type chemicals aromatic amines, and pesticides. Insecticides of pesticide type were frequently detected at all sampling site. The total concentration of micropollutants were higher in summer than in winter and measured within the range of $ND{\sim}36.50{\mu}g/L$. Also, because of effect of seomjin river, GY6 of all sampling site detected by the highest concentration, GY10 and 11 located in Gwang-yang outside bay were not detected the micropollutants. From the result of this study, we should estimated that the industrial complex located in Gwang-yang inside bay and an inflow of fresh water through the Seomjin river are major pollution sources of Gwang-yang bay.

• Journal of the korean society of oceanography
• /
• 제38권4호
• /
• pp.166-172
• /
• 2003

Multi­Sensor Core Logger (MSCL) is a useful system for logging the physical properties (compressional wave velocity, wet bulk density, fractional porosity, magnetic susceptibility and/or natural gamma radiation) of marine sediments through scanning of whole cores in a nondestructive fashion. But MSCL has a number of problems that can lead to spurious results depending on the various factors such as core slumping, gas expansion, mechanical stretching, and the thickness variation of core liner and sediment. For the verification of MSCL data, compressional wave velocity, wet bulk density, and porosity were measured on discrete samples by Hamilton Frame and Gravimetric method, respectively. Acoustic impedance was also calculated. Physical property data (velocity, wet bulk density, and impedance) logged by MSCL were slightly larger than those of discrete sample, and porosity is reverse. Average difference between MSCL and discrete sample at both sites is relatively small such as 22­24 m/s in velocity, $0.02­-0.08\;g/\textrm{cm}^3$ in wet bulk density, and 2.5­2.7% in porosity. The values also show systematic variation with sediment depth. A variety of factors are probably responsible for the differences including instrument error, various measurement method, sediment disturbance, and accuracy of calibration. Therefore, MSCL can be effectively used to collect physical property data with high resolution and quality, if the calibration is accurately completed.

• 한국습지학회지
• /
• 제4권1호
• /
• pp.21-31
• /
• 2002

Vegetation structure and sediment properties were investigated in the Wondong wetland of the Nakdong-gang, Yangsan-city, Gyeongsangnam-do, Korea. The vegetation type was classified into eleven communities based on the actual vegetation map: Miscanthus sacchariflorus community, Salix nipponica community, Phragmites communis community, Zizania latiofolia community, Trapa japonica community, Hydrilla verticillata community, Hydrocharis dubia community, Digitaria sanguinalis community, Nelumbo nucifera community, Phragmites japonica community, and Salix matsudana for. tortuosa community. Among them, Distribution area of Miscanthus sacchariflorus community was largest as 12.4 ha (36.3%). The dominant vegetation type was Miscanthus sacchariflorus community based on phytosocialogical method, and it was classified into two subcommunities; Persicaria maackiana - Miscanthus sacchariflorus subcommunity and Hydrilla verticillata - Miscanthus sacchariflorus subcommunity. Ranges of the sediment properties such as pH, conductivity, organic matter, total nitrogen, and available phosphorus were 4.9~6.2, $23{\sim}423{\mu}mho/cm$, 0.37~11.16%, 0.02~0.36% and 0.14~0.38mg/100g, respectively. Percentages of the partical size of the sediment such as clay, silt, and sand were 5.0~27.0%, 6.7~31.3%, and 46.7~88.3%, respectively.