• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.3
• /
• pp.265-272
• /
• 2007

This study uses the SWAT model to analyze the characteristics of long-term runoff at the Ssang-cheon Basin located in the city of Sokcho, which is located in the province of Gangwon. The study considers the effect of snow packing and snow melting in a runoff simulation. In this simulation, the study examines the need to introduce a snow pack and snow melt model to evaluate the water resources of the mountainous region of the Gangwon province. The findings of this study indicate that the runoff hydrograph that was produced approximates the true measured flow when the effect of the snow pack and snow melt are considered, compared to when they are not factored in. The analysis of the flow duration curve indicates that the stream flow largely increases when the effect of the snow pack and snow melt are considered. The wet stream flow was shown to increase by nearly 3% due to the melting effect, while the normal stream flow, low stream flow and drought stream flow were shown to increase by slightly more than 10%. Specifically, it was found that as the stream flow decreases, the effect of the snow pack and snow melt on the stream flow increases.

• Journal of Korean Society on Water Environment
• /
• v.29 no.3
• /
• pp.343-353
• /
• 2013

Flow duration curve (FDC) can be developed by linking the daily flow data of stream flow monitoring network to 8-day interval flow data of the unit watersheds for the management of Total Maximum Daily Loads. This study investigated the applicable method for the development of long term FDC with the selection of the stream flow reference sites, and suggested the development of the FDC in 4 river basins. Out of 142 unit watersheds in 4 river basins, 107 unit watersheds were shown to estimate daily flow data for the unit watersheds from 2006 to 2010. Short term FDC could be developed in 64 unit watersheds (45%) and long term FDC in 43 unit watersheds (30%), while other 35 unit watersheds (25%) were revealed to have difficulties in the development of FDC itself. Limits in the development of the long term FDC includes no stream monitoring sites in certain unit watersheds, short duration of stream flow data set and missing data by abnormal water level measurements on the stream flow monitoring sites. To improve these limits, it is necessary to install new monitoring sites in the required areas, to keep up continuous monitoring and make normal water level observations on the stream flow monitoring sites, and to build up a special management system to enhance data reliability. The development of long term FDC for the unit watersheds can be established appropriately with the normal and durable measurement on the selected reference sites in the stream flow monitoring network.

• Journal of Korean Society on Water Environment
• /
• v.29 no.1
• /
• pp.55-65
• /
• 2013

It is very difficult to apply stream flow data directly to the management of Total Maximum Daily Loads because there are some differences between the unit watershed and the stream flow monitoring network in their characteristics such as monitoring locations and its intervals. Flow duration curve can be developed by linking the daily flow data of stream monitoring network to 8 day interval flow data of the unit watershed. This study investigated the current operating conditions of the stream flow monitoring network and the flow relationships between the unit watershed and the stream flow monitoring network. Criteria such as missing and zero value data, and correlation coefficients were applied to select the stream flow reference sites. The reference sites were selected in 112 areas out of 142 unit watersheds in 4 river basins, where the stream flow observations were carried out in relatively normal operating conditions. These reference sites could be utilized in various ways such as flow variation analysis, flow duration curve development and so on for the management of Total Maximum Daily Loads.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.10 no.1
• /
• pp.86-95
• /
• 1986

A study on film water flow on steep open channel has been seldom found up to date. Therefore, this paper dealed with the depth variation of film thickness of water (city supply normal water) flowing on steep open channel. For this purpose, Experimental apparatus (made of a normal glass with 160cm of length and 15cm of width) was made and the depths of the water flowing on the channel were measured experimentally, changing the channel slope angle from 30 to 80 degree (5 steps) and the flow rate from 0.25 to 10CPM (11 steps). The results obtained, some characteristics of the film flow on the channel are as follows. (1) When thin film water flowed on steep open channel, the depths of flow tended to increase after decreasing and was kept nearly constant in its downstream in case of laminar and transitional flow region. The turining point of the depths of flow from decrease to increase tended to move downward with the increase of Reynolds number. In turbulent flow region, the depths of flow showed reapid decrease in its upper stream, gradual decrease in its midstream and were kept nearly constant in its downstream. (2) While the differences between the depths of flow along the channel slope got small in its upper stream and got large in its downstream in case of laminar flow region, they got very large in its upper stream and were kept nearly constant in its downstream in case of transitional and turbulent flow region. And the move flow rate increases, the more the differences between the depths of flow along the channel slope got large in its upper stream.

• Korean Journal of Agricultural Science
• /
• v.38 no.1
• /
• pp.163-172
• /
• 2011

To provide the operation rule curve for suppling instream flow to urban stream from reservoir, the Soho reservoir with watershed area of 7.4 $km^2$ and total water storage of 2.58 $Mm^3$ was planned at the headwaters of the Daejeoncheon. Daily streamflow was simulated and using the simulated streamflow and desired instream flow, the operation rule curve by Senga method was drawn and evaluated through reservoir operation. Senga method is derived by accumulating the differences between streamflow and desired instream flow adversely. Water storages were simulated on a daily basis to supply urban instream flow from Soho reservoir, but the amount of supplying instream flow to urban stream was not nearly increased comparing with that of normal operation that does not used the rule curve. Thereafter the new simulation-based operation rule curve was derived and applied to supply instream flow from Soho reservoir. In normal operation, the amount of instream flow was shown to 15,000 $m^3$/d, but it was increased to 27,700 $m^3$/d in withdrawal limited operation using the new derived rule curve, in which the applicability of this rule curve was proved. Also comparing with the flow duration curves at station just before urban Daejeoncheon stream without and with upstream Soho reservoir, the 95th flow was decreased from 1.64 mm/d to 1.51 mm/d, and the 355th flow was increased from 0.17 mm/d to 0.30 mm/d. Monthly streamflows during October to March were increased from 10.6~24.1 mm to 24.1~34.0 mm with the increasing rate of 141~227%.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.10a
• /
• pp.263-270
• /
• 1997

For a cylinder in a uniform flow stream, sound is generated by the fluctuating pressure on the cylinder surface due to the vortex shedding behind the cylinder. It is known that the major parameters to predict the sound pressure are the characteristic length of the flow along the cylinder axis and the fluctuating lift coefficient. These parameters strongly depend on the Reynolds number and the yaw angle of the cylinder to the free stream. In this experimental study the effects of yaw on the flow parameters, and consequently on the generated sound are investigated. The surface pressure and the radiated sound are measured simultaneously for different yaw angles and showed that the reduced normal velocity component to the cylinder axis reduces the unsteady lift fluctuation which results in lowered sound press-are level, However, experimental result shows that "the cosine law" which uses the normal velocity component as a characteristic velocity for noise Generation from a yawed cylinder needs to be carefully reviewed. reviewed.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.10
• /
• pp.3668-3684
• /
• 2021

Video action recognition is widely used in video surveillance, behavior detection, human-computer interaction, medically assisted diagnosis and motion analysis. However, video action recognition can be disturbed by many factors, such as background, illumination and so on. Two-stream convolutional neural network uses the video spatial and temporal models to train separately, and performs fusion at the output end. The multi segment Two-Stream convolutional neural network model trains temporal and spatial information from the video to extract their feature and fuse them, then determine the category of video action. Google Xception model and the transfer learning is adopted in this paper, and the Xception model which trained on ImageNet is used as the initial weight. It greatly overcomes the problem of model underfitting caused by insufficient video behavior dataset, and it can effectively reduce the influence of various factors in the video. This way also greatly improves the accuracy and reduces the training time. What's more, to make up for the shortage of dataset, the kinetics400 dataset was used for pre-training, which greatly improved the accuracy of the model. In this applied research, through continuous efforts, the expected goal is basically achieved, and according to the study and research, the design of the original dual-flow model is improved.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.5 no.3
• /
• pp.25-32
• /
• 2001

A passive control method of the interaction between a weak normal shock-wave and a turbulent boundary-layer was simulated using two-dimensional Navier-Stokes computations. The inflow Mach number just upstream of the normal shock wave was 1.33. A porous plate wall having a cavity underneath was used to control the shock-wave/turbulent boundary-layer interaction. The flows through the porous holes and inside the cavity were investigated to get a better understanding of the flow physics involved in this kind of passive control method. The present computations were validated by some recent wind tunnel tests. The results showed that downstream of the rear leg of the $\lambda$-shock wave the main stream inflows into the cavity, but upstream of the rear leg of the $\lambda$-shock wave the flow proceeds from the cavity toward to the main stream. The flow through the porous holes did not choke fur the present shock/boundary layer interaction.

• Journal of Korea Water Resources Association
• /
• v.51 no.3
• /
• pp.207-219
• /
• 2018

In this study, the ecological flow rate of the Zacco playtypus habitat was simulated based on the Instream Flow Incremental Methodology (IFIM) in reachs of urban and natural stream using the habitat suitability index (HSI) of the probability density function (PDF). To apply this method, PHABSIM model was used in this study. However, in this study, the HSI of the probability density function was developed by adjusting the parameters of the PDF based on Kang (2010) HSI. As a result, the normal distribution is closest to the ecological flow rate of the Kang (2010) in the urban stream. However, the two-parameter log-pearson distribution tended to be the closest in the natural stream. The ecological flow rate was simulated by the HSI and the reach of stream with the PDF. Based on the comparison of simulation results, we propose an ecological flow rate estimation method using probabilistic method.

• Journal of ILASS-Korea
• /
• v.1 no.2
• /
• pp.66-73
• /
• 1996

The present study investigates experimentally the characteristics of liquid jet, which is, the spray flow in the normal direction of the air stream under the flow conditions of air velocity $110\sim125m/s$. The present study adopts with the flow visualization technique using a short duration light bulb and the image processing analyse with CCD camera. Two types of injector were used: one is a flat plate type, and the other is backward facing step type, which height are 5, 8, 10mm. Dispersion of liquid jet can be represented by gray level of CCD camera. In the upstream of liquid jet, the backward facing step shows better liquid jet penetration. However, in the downstream. mean droplet size for backward facing step injector is smaller than that for flat plate injector