• Journal of Korean Society of Disaster and Security
• /
• v.16 no.1
• /
• pp.81-89
• /
• 2023

Recently, due to global warming and urbanization due to the influence of abnormal weather, weather changes are increasing worldwide. Various measures have been proposed to reduce flood damage as flood volume increases due to problems such as an increase in impermeable area due to urbanization and reckless development. In this study, flow characteristics and overflow volume were analyzed using FLOW-3D, a three-dimensional CFD model, in accordance with changes in the cross-flow weir inlet angle installed in the meandering river section, and a basic study was conducted to evaluate the overflow capacity and calculate the flow coefficient. As a result of the analysis, the smaller the inflow angle of the transverse overflow, the lower the water level and flow rate of the main water flow after passing the transverse overflow, and the higher the inflow angle, the higher the water level and the flow rate. In addition, it was confirmed that the direct downstream flow rate decreased compared to the upstream flow rate when the inflow angle of the transverse overflow was 40° or higher.

• Journal of Aquaculture
• /
• v.16 no.4
• /
• pp.216-222
• /
• 2003

In a simulated seawater aquaculture system, effects of different operating factors like the superficial air velocity (SAY), hydraulic residence time (HRT), protein concentration and foam overflow height on the removal of total suspended solids (TSS) by a foam fractionator, with 20 cm diameter and 120 cm height, were investigated. This experiment was performed on batch and consecutive modes for different combinations of the tested factors, using synthetic wastewater. In 5 consecutive trials, TSS concentration in culture tank water decreased faster, when the foam fractionator was operated at higher SAV and lower HRT. In batch trials, with increasing SAV, TSS removal rate increased, but decreased with increasing HRT. Higher protein concentration in the bulk solution resulted in higher TSS removal rate. TSS concentration in the collected foam condensates increased but the foam overflow rate decreased with increasing foam overflow height. Foam fractionation was effective for removing TSS in seawater aquaculture systems and its performance largely depended on the operating parameters, especially superficial air velocity.

• Proceedings of the IEEK Conference
• /
• 1999.11a
• /
• pp.1041-1044
• /
• 1999

This paper propose a solution to resolve data overflow or leakage when a subscriber receive data to service provider. The set-top box can communicate with a service provider and can inform the service provider its data overflow or leakage. When service provider received this control signal, it changes data transmit rate and transmits data with changed rate. The buffer of set-top box is important because incoming data from a service provider are stored by it.

• Proceedings of the IEEK Conference
• /
• 2003.07e
• /
• pp.1719-1722
• /
• 2003

Image enhancement를 하기 위한 영상처리 알고리즘 중의 하나인 contrast enhancement 알고리즘은 화면의 flickering 과 같은 부작용과 조절 가능한 contrast enhancement rate 에 대한 구현의 어려움 등으로 실제 TV와 같은 동영상에 적용하기에 어려움이 있었다. 본 논문에서는 Bin Underflow Bin Overflow(BUBO)를 이용하여 동영상에 적용할 경우에도 flickering 등의 부작용이 생기지 않으며 contrast enhancement rate 을 조절할 수 있는 효율적인 알고리즘을 제안한다. 또한 이와 관련하여 영상의 휘도 레벨에 있어서 어두운 영역의 계조와 밝은 영역의 계조를 향상시킬 수 있는 black/white level stretch 알고리즘과 전체 화면의 출력 휘도 레벨에 대한 dynamic range를 유지하면서 brightness를 조절할 수 있는 알고리즘을 제안한다.

• 한국방재학회:학술대회논문집
• /
• 2008.02a
• /
• pp.191-194
• /
• 2008

Labyrinth weir is a hydraulic structure that can maintain constant water depth and increase overflow rate by increasing overflow width of weir through complicated displacement of its cross section. The labyrinth weir can be widely applied to various hydraulic facilities such as dam spillway, irrigation facilities, and canal structures. To date, however, few labyrinth weirs were applied to hydraulic facilities in Korea. Hence, in-depth research on labyrinth weir is highly required to efficiently apply the labyrinth weir to hydraulic facilities. This study was performed to analyze the hydraulic characteristics according to triangle labyrinth weir using hydraulic model experiments. The hydraulic characteristics provided in this study, which make it feasible to increase the overflow rate, and are expected to be widely applied to design of hydraulic facilities such as dam spillway and irrigation system.

• Proceedings of the SAREK Conference
• /
• 2005.11a
• /
• pp.129-134
• /
• 2005

The behavior of whole system is affected by a minor change of system in the hydronic radiant floor heating system. Under partial load condition, the change of system resistance causes overflow of supply water. This unexpected effect is the cause of several problems in the heating system. In this study, we find some factors were validated with several computer simulations. After validation of this result, several conceptual solutions are evaluated to prevent overflow.

• Environmental Engineering Research
• /
• v.20 no.3
• /
• pp.298-305
• /
• 2015

The Standards for Water Works issued by the Korean government prescribed the insertion of inclined plates in a clarifier to enhance the settling of the suspended solids. In this study, in order to verify the role of the inclined plates, two identical laboratory-scale rectangular clarifiers were constructed and eight inclined plates were inserted into one of the clarifiers and inflow from same source was treated in both the clarifiers. Dye tests revealed that only the front three of the seven slots received the inflow at $0.57m^3/m^2{\cdot}h$, which was the highest SOR (surface overflow rate). Three different SORs, with 12 different SS (suspended solid) concentrations at each overflow rate, were fed to both clarifiers. However, the clarifier with the inclined plates failed to show an improved removal rate for the SS. In order to enable the Boycott effect within the slot, it is suggested that each slot created by the inclined plates receives equalized inflow. Moreover, collision of the inflow with the settled sludge at the bottom of the clarifier has to be avoided. These provisions, which can maximize the Boycott effect, should be added to the Standards for Water Works endorsed by Korean government.

• Membrane and Water Treatment
• /
• v.11 no.1
• /
• pp.49-57
• /
• 2020

The effect of Combined Sewer Overflow on the river system was investigated throughout three preliminary field tests and three main ones. As a result of the study, Combined Sewer Overflow did not affect water qualities on the main stream since the concentration of the main stream did not significantly changed during rainfall events although the water quality of tributaries has rapidly deteriorated due to the influence of the Combined Sewer Overflow during rainfall events. The main cause of the result is that the flow rate of the tributaries is considerably lower than that of the main stream, so that the tributaries with deteriorated water quality during rainfall events did not significantly affect the quality of the actual main stream. Therefore, the water quality of the Kumho River is more affected by the wastewater treatment facilities that discharges water continuously to the main stream than pollutants from non-point pollution sources during rainfall events. As a result, managements for discharges from wastewater treatment facilities should be strengthened in order to improve the water quality of the river.

• ETRI Journal
• /
• v.33 no.4
• /
• pp.580-588
• /
• 2011

This paper proposes reversible data hiding using minimum/maximum preserved overflow/underflow avoidance (MMPOUA). The proposed MMPOUA algorithm consists of three main steps. These steps include the minimum (or maximum) pixel fixing, pixel squeezing, and pixel isolation. The aims of pixel fixing are to keep the minimum (or maximum) pixel of a host block unchanged and prevent the occurrence of overflow/underflow. Both the pixel squeezing and pixel isolation supply hiding storage while keeping the amount of distortion low. The proposed method can avoid (or significantly reduce) the overhead bits used to overcome overflow/underflow issues. At an embedding rate of 0.15 bpp, the proposed algorithm can achieve a PSNR value of 48.52 dB, which outperforms several existing reversible data hiding schemes. Furthermore, the algorithm performed well in a variety of images, including those in which other algorithms had difficulty obtaining good hiding storage with high perceived quality.

• Computers and Concrete
• /
• v.29 no.4
• /
• pp.209-217
• /
• 2022

In order to analyze the static and dynamic structural characteristics of the Obermeyer gate under overflow conditions, the force characteristics and vibration characteristics of the shield plate structure are studied based on the fluid-solid coupling theory. In this paper, the effects of the flow rate, airbag pressure and overflow water level on the structural performance of shield plate of air shield dam are explored through the method of controlling variables. The results show that the maximum equivalent stress and total deformation of the shield plate decrease first and then increase with the flow velocity. In addition, they are positively correlated with the airbag pressure. What's more, we find that the maximum equivalent stress of the shield plate decreases first and then increases with the overflow water level, and the total deformation of the shield plate decreases with the overflow water level. What's more importantly, the natural frequency of the shield structure of the Obermeyer gate is concentrated at 50 Hz and 100 Hz, so there is still the possibility of resonance. Once the resonance occurs, the free edge of the shield vibrates back and forth. This work may provide a theoretical reference for the safe and stable operation of the shield of the Obermeyer gate.