• Journal of Ocean Engineering and Technology
• /
• v.21 no.3 s.76
• /
• pp.40-45
• /
• 2007

This study was performed to investigate the effect of various propeller tunnel shapes on the propulsion performance of a fishing boat. The propeller tunnel reduces the problem resulting from the open propeller accidentally catching the waste net and cable on the sea, as well as increasing the cruising speed. For 3 different tunnel geometries, the model test is conducted in the circular water channel, and the potential based panel method was applied to analyze the hydrodynamic characteristics of propeller. Also, both results are compared with each other to represent the difference between results of the model scale test and the potential theory. It is expected that these results could be referenced in the design of the propeller tunnel in consideration of the hydrodynamic interaction between the propeller and the tunnel.

• 한국전산유체공학회:학술대회논문집
• /
• 2005.10a
• /
• pp.239-243
• /
• 2005

Fully three-dimensional Large Eddy Simulation calculations of the flow past 2D cavity are conducted to study the purging of neutrally buoyant or dense miscible contaminants introduced instantaneously inside the cavity. The length to depth ratio(L/D) is 2 and Reynolds number based on the depth is 3,360. Fully developed turbulent inflow are fed at the inlet from precursor simulation of channel flow. Mean flow pattern and unsteady features are investigated based on the experimental data of Pereira and Sousa. From the study of mass exchange processes, it is found that the mechanism of removal of the contaminant is very different between the non-buoyant and buoyant cases. In the buoyant case, internal wave motion which interacts with a strong cavity vortex is dominant in the ejection mechanism of the contaminants.

• Journal of Electrical Engineering and Technology
• /
• v.2 no.4
• /
• pp.518-524
• /
• 2007

This paper describes several improved characterizations of the EPIC CCD, which now has modified electrode and channel structures. From a 3-D numerical simulation of the device, its channel doping and potential distributions are then observed for the optimization of the charge transfer. A wavelength-dependence on the device structure is observed in terms of the reflectivity of the incident radiation. The optical properties of ultra-low energy levels, when using an open-electrode structure, are then considered to improve their quantum efficiency.

• Korean Journal of Hydrosciences
• /
• v.3
• /
• pp.45-59
• /
• 1992

The flow characteristics varying with rate of the radius of curvature to width (Rc/B) in open channel bends are investigated with a simplified numerical model. Secondary flow velocity and transverise bed slope are formulated from the equations of momentum and force balance analysis, respectively. The conservation equations of mass and streamwise momentum are simplified by depth integration and its solution could be obtained from the explicit finite difference method. Three sets of computer simulation are executed. The rates of Rc/B adopted in simulations are 2.7, 5.4 and 8.1. The terms analyzed in this paper secondary flow velocity, streamwise velocity, the path of maximum steamwise velocity, deviation angle, and mass-shift velocity.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.1269-1271
• /
• 2008

We find some array mura are caused by S/D bridge or channel open in 4 mask process. The gray tone PR thickness non-uniformity is the main reason of these defects. By the adjustment of exposure and dry etch parameters, S/D bridge and channel open ratio drops by 10.87%.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.160.1-160.1
• /
• 2011

In this study, the influence of methodology of assessing water levels on the discharge coefficient of sluice for tidal power generation was investigated. A physical experiment was performed in a planar open channel by installing 1/70 scale model of the sluice caisson in the planar open channel. In front of and behind the sluice model, sloping bathymetry was made to reproduce corresponding field condition. By analyzing the experimental results, it was found that the location of measuring water levels significantly affects the estimates of the discharge coefficient, due to the variability of the parameter according to the head difference between the measuring locations. Therefore, it is necessary to be careful in estimating and utilizing the discharge coefficient in the relevant study of a tidal power generation.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.7
• /
• pp.1297-1298
• /
• 2008

• 한국방재학회:학술대회논문집
• /
• 2008.02a
• /
• pp.401-404
• /
• 2008

The vegetation in the surrounding area of river is a primary factor to increase water level during flood. The influence of vegetation on the river flow in a bank has been investigated by using a hydraulic experiment. For a hydraulic experiment square-shaped piers are used as a model of unsubmerged rigid vegetation in a open channel. For fully developed uniform flows, the water elevation of the experiment was measured as varying the interval of piers and the porosity which presents the fraction of water flowing area in the cross-sectional area. The Manning's roughness coefficient, which implicates energy losses due to the vegetation, was obtained by using the experimental data. As a result, the energy losses were varied when the distance of piers and the porosity of area were changed, and the Manning's coefficient increased nonlinearly when a water elevation increased.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.9 no.2
• /
• pp.53-57
• /
• 2009

The dividing flow in an open channel has a number of distinctive characteristics. One of these is that the separation zone interacts with a secondary motion along the inner wall of a branch channel, generating sediment accumulation. To investigate this phenomenon, a two-dimensional numerical model based on the shallow-water equations, RMA2, which calculates water surface elevations and horizontal-velocity components, was used to analyze the dividing flow. The obtained numerical results fully coincide with the laboratory measurements reported by Hsu et al.(2002). For the analysis of the numerical results, a separation zone-discharge rate relationship was proposed. To reduce the size of a separation zone, the topographies of diagonal and curved edges were proposed, smoothly connecting the upstream corner to branch channel.

• Journal of Information Technology Applications and Management
• /
• v.19 no.2
• /
• pp.249-263
• /
• 2012

Recently the open innovation is considered as one of the important issues for the survival strategy of a company in the industry. There have been several researches and practices on this topic. However, previous researches are mainly focused on the study of successful cases and some statistical analyses on the relationship between the open innovation and its performance. There are rare researches on the hindrance factors in the practical level. This paper tries to find some hinderance factors for the open innovation in Korean large-scale companies based on the WFGM(Want-Find-Get-Manage) model proposed by Gene Slowinski(2006). Especially this research focused on each processes of open innovation by in-depth interviews for two representative large companies in Korea. From the result of this research we come to know that the critical hindrance factor in the WANT step is the uncertain definition of the necessary technologies for the company. Issues on establishing and maintaining the innovation network are in the FIND step. Technology evaluation, technology introduction channel and technology copying issues are in the GET step. Communication issues, technology feasibility and lack of competition are in the MANAGE step. This paper finds some hindrance factors in each process step of open innovation, which gives some implications for the companies that want to adopt open innovation.