• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2005년도 학술발표회(1)
• /
• pp.610-611
• /
• 2005

• International Journal of Ocean System Engineering
• /
• 제2권2호
• /
• pp.71-81
• /
• 2012

Several methods have been proposed to control the sedimentation process. These include catchment management, flushing, sluicing, density current venting, and dredging. Flushing is used to erode previously deposited sediments. In pressurized flushing, the sediment in the vicinity of the outlet openings is scoured and a funnel shaped crater is created. In this study, the effect of localized vibrations in the sediment layers on the dimensions of the flushing cone was investigated experimentally. For this purpose, experiments were carried out with two bottom outlet diameters, five discharge releases for each desired water depth, and one water depth above the center of the bottom outlets. The results indicate that the volume and dimensions of the flushing cone are strongly affected by localized vibrations.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2005년도 학술발표회(1)
• /
• pp.252-252
• /
• 2005

• 한국해양공학회지
• /
• 제27권2호
• /
• pp.107-113
• /
• 2013

Most natural river reach are approximately balanced with respect to sediment inflow and outflow. Dam construction dramatically alters this balance, creating an impounded river reach characterized by extremely low flow velocities and efficient sediment trapping. The impounded reach will accumulate sediment and lose storage capacity until a balance is again achieved, which would normally occur after the impoundment has become "filled up" with sediment and can no longer provide water storage and other benefits. This paper aims to investigate the sediment removal process in dam reservoir using simultaneously pressure flushing operation and vibrator machine. The main objective of this study is to identify the effect of vibrator in flushing cone dimensions. To achieve the objectives of present study, laboratory test have conducted under different hydraulic conditions such as two bottom outlets with diameter equal to 2" and 3", five discharges 0.23, 0.53, 1.21, 1.53 and 2.1 lit/s and only one water depth above the center of bottom outlets. Using the vibrator machine mounted into the reservoir and close to the bottom outlet, different frequency e.g. 20, 35 and 50 HZ, have been introduced to the deposited sediment at the vicinity of outlet. The results indicate that the volume and width of flushing cone are strongly affected by frequency of vibrations. The results indicate that the volume and width of flushing cone are strongly affected by frequency of vibrations.

• 상하수도학회지
• /
• 제25권5호
• /
• pp.627-634
• /
• 2011

In the present study, the flow behaviors of square jets surface discharged and submerged discharged into shallow water were each simulated using computational fluid dynamics, and the results were compared. As for the verification of the models, the results of the hydraulic experiment conducted by Sankar, et al. (2009) were used. According to the results of the verification, the present application of computational fluid dynamics to the flow analysis of square jets discharged into shallow water was valid. As for the wall jet, which is one form of submerged discharges, at the bottom wall boundary, the peak velocity of the jet rapidly moved from the center of the jet to the bottom wall boundary due to the restriction of jet entrainment and the no-slip condition of the bottom wall boundary, and, as for the surface discharge, because jet entrainment is limited on the free water surface, the peak velocity of the jet moved from the center of the jet to the free water surface. This is because jet entrainment is restricted at the bottom wall boundary and the surface so that the momentum of the central core of the jet is preserved for considerable time at the bottom wall boundary and the surface. In addition, due to the effect of the bottom wall boundary and the free water surface, the jet discharged into shallow water had a smaller velocity diminution rate near the discharge outlet than did the free jet; at a location where it was so distant from the discharge outlet that the vertical profile of the velocity was nearly equal (b/x =20~30), moreover, it had a far smaller velocity diminution rate than did the free jet due to the effect of the finite depth.

• 한국태양에너지학회 논문집
• /
• 제21권2호
• /
• pp.35-43
• /
• 2001

The results of numerical simulation on the performance of a solar chimney system in building are described. The inside surface temperature of four walls within the solar chimney arc calculated with solar radiation and outdoor temperature in summer. The air within the solar chimney is heated by conduction, convection and radiation. Air temperature distribution from the bottom to the top and outlet air temperature can be obtained by solving energy balance equation. Since the buoyance or stack effect is affected by temperature difference between the bottom and the top within the solar chimney. It is evaluated using inlet and outlet temperatures. It is expected that natural ventilation by the solar chimney of witch the height is 7.8m and the cross sectional area is $4.93m^2$ can provide about $6400m^3/h$ on sunny day.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2005년도 학술발표회(2)
• /
• pp.1274-1275
• /
• 2005

• Korean Chemical Engineering Research
• /
• 제44권3호
• /
• pp.294-299
• /
• 2006

백-형상 필터의 투과율에 따른 필터 표면에서의 유동속도와 입자궤적을 수치해석 하였다. 필터의 투과율이 널리 사용되는 저급의 부직포 백필터의 투과율 이하의 조건에서는, 투과율에 따른 필터 표면에서의 유동속도와 입자궤적 분포의 변화가 아주 미미하였다. 필터의 바닥면 모서리와 출구 근처를 제외한 필터 표면에서 유선들과 반경 방향 유속들이 균일하게 분포하였다. 필터 표면으로의 입자궤적은 필터의 바닥면 모서리 근처에 더 조밀하게 분포하여 그 위치에 도달하는 입자의 수가 가장 많았고, 필터의 출구 쪽으로 향함에 따라 필터 표면에 위치하는 입자의 수는 점점 감소하는 추세를 보였다.

• 한국농공학회지
• /
• 제42권6호
• /
• pp.83-89
• /
• 2000

A depot encircled with contact oxidation canal has been developed to improve water qualityr. The depot is aimed to settle suspended solid in the flow. The oxidation canal is to contact the pollutants and oxygen in the surface of gravel filter to purify the water. The deposit of the pollutant in the depot is released by the drainage culvert located at the bottom of it. Aeration nozzle is installed to supply enough oxygen to the gravel filter layers in the bottom of the detent the flow and improve oxidation efficiency. From the experiment it is founded that 91% of SS, 39% of TN, 63% of TP and 77% of COD were removed in the system. The treatment efficiency of total nitrogen is rather lower than any other components, however, it would be higher when some floating vegetation is added in the primary clarifier. The depot and oxidation canal system would be useful to purify the flows in the mouth of the reservoirs or at the outlet of the drainage canal.

• Clinics in Shoulder and Elbow
• /
• 제1권2호
• /
• pp.250-255
• /
• 1998

Purpose of the study was to analyze the supraspinatus outlet image of sagittal MRI in rotator cuff disease. We analyzed the sagittal views of the shoulder MRI of 78 cases without cuff tear. The cases were divided into 51 cases of rotator cuff disease group and 27 cases of control group. Six parameters of acromial tilt, coracoacromial ligament angle, length and height of coracoacromial triangle, length of acromial side of the baseline and distance of intrusion of the humeral head were compared for each group. The distance of intrusion of the humeral head was the most significantly different one, 0.52cm for rotator cuff disease group and 0.15cm for control group. Intrusion of the humeral head to the supraspinatus outlet space from the bottom may be a contributing factor developing rotator cuff disease. The intrusion may precede to tearing of the rotator cuff.