• Water Engineering Research
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• v.3 no.3
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• pp.155-162
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• 2002

This study presents the theoretical approach for volume concentration, velocity profile, and granular discharge on the fluid-granule mixed flow downstream of the scour hole at the outlet of the hydraulic structure. Concept of dilatant model was applied for the stress-strain relationships of fluid-granule mixed flow since the flow downstream of the scour hole corresponds to debris flow, where momentum transfers through particle collisions. Mathematical formulations were derived using momentum equation and stress-strain relation of the fluid-granule mixture. Velocity profile under the assumption of uniform concentration over flowing layer showed the downward convex type. Deposition angle of downstream hump was found to be a function of an upstream slope angle, a dynamic friction angle and a volume concentration irrespective of flow itself, Granular discharge and the overflow depth were obtained with given values of inflow rates. Experimental results showed relatively good agreements with theoretical ones.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.407-412
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• 2011

Recently, the Malaysian government had been developing new technologies to the construction industry and one of them is the Industrialised Building System (IBS). The government urged that IBS is 100% utilized in all construction projects. It is believed that the application of IBS helps in reducing construction duration and cost, solving the problems of overflow of foreign workers in the site and improving performance and appearance of a structure. However, there are some parties like the contractor who feel reluctant to utilize this system because there are risks. They worry that their trades will be affected as IBS construct a structure using components which are manufactured in a factory and assemble on site. Therefore, this research is to find out whether IBS benefits the country's economy by focusing on the business created by investing in IBS. A comprehensive supply chain for IBS will be developed to compare with the traditional construction supply chain as to determine businesses or trades created and eliminated. This paper is looking at the theoretical framework about business opportunities due to the Government policy on embarking IBS.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.8-15
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• 2005

Wave energy has been considered to be one of the most promising energy resources for the future, as it is pollution-free and an abundant natural resource. However, since it has drawbacks of non-stationary energy density, it is necessary to change the wave energy into a simple concentrated energy. Progressive waves in a coastal area can be amplified, swashed, and overtopped by a wave overtopping control structure. By conserving the quantity of overflow in a reservoir, the kinetic energy of the waves can be converted to the potential energy with a hydraulic head above the mean sea level. The potential energy in the form of a hydraulic head can be utilized to produce electric power, similar to hydro-electric power generation. This study aims to find the most optimal shape of wave overtopping structure for maximum overtopping volume of sea water; for this purpose, we carried out the wave overtopping experiment in a wave tank, under both regular and irregular wave conditions.

• Journal of Ocean Engineering and Technology
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• v.21 no.1 s.74
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• pp.25-30
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• 2007

Most of dams and reservoirs were made from natural materials, such as soil, sand and gravel. This type of hydraulic structure has the danger of collapse by overflow during a flood. Freeboard is the vertical distance between the crest of the dam and the full supply level in the reservoir. It must be sufficient to prevent overtopping from over flow. Thus, freeboard determination involves engineering judgment, statistical analysis, and consideration of the damage that would result from the overtopping of a hydraulic structure. This study attempts to calculate the wave height in dam, which is needed for the determination of the freeboard of the dam. Chung-ju dam is selected as the study area. Using the empirical formulas, the wave heights in dam were calculated, and the results were compared with those by the SWAN model, which is a typical wave model. The difference between the calculated results from the empirical formulas and those by the SWAN model is considerably large. This is because empirical equations consider only fetch or fetch and wind velocity, while the SWAN model considers depth and topography data as well.

• Journal of Korea Water Resources Association
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• v.41 no.2
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• pp.197-212
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• 2008

Recently, stream flow analysis has been accomplished by one or two dimensional equations and was applied by simple momentum equations and fixed energy conservations which contain many condition limits. In this study, FLOW-3D using CFD (Computational Fluid Dynamics) was applied to stream flow analysis which can solve three dimensional RANS (Reynolds Averaged Navier-Stokes Equation) control equation to find out physical behaviors and the effect of hydraulic structures. Numerical simulation accomplished those results was compared by using turbulence models such as ${\kappa}-{\varepsilon}$, RNG (Renormalized Group) ${\kappa}-{\varepsilon}$ and LES (Large Eddy Simulation). Numerical analysis results have been illustrated by the turbulence energy effects, velocity of flow, water level pressure and eddy flows around the piers and transverse overflow type structures. These results will be able to used by basis data that catch hold of effects on long-term bed elevation changes, sediment accumulations, scours and water aggravations by removal of obsolete transverse over flow type structures in urban stream.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.393-399
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• 2005

The purpose of this study is to suggest some references of maintenance and design of concrete gravity dams by analyzing dynamic characteristics in x, y, z directions. It is considered as additional mass, soil interaction for numerical dynamic analysis for gravity concrete dams in Han River basin as some cases. The result shows that the overflow structure can be possibly underestimated for the evaluation of the seismic performance using seismic intensity, modified seismic intensity methods. A much more research is still necessary for the evaluation of comprehensive seismic performance of concrete gravity dam

• Journal of Korea Multimedia Society
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• v.21 no.9
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• pp.1090-1098
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• 2018

MQTT is a lightweight messaging protocol that can be used for low power IoT devices. The MQTT basically uses single MQTT broker to indirectly share message information between publishers and subscribers. This approach has a weakness in regard to traffic overflow, connection fault, security, etc. In this paper, we propose a distributed MQTT broker architecture that solves the problems in single MQTT broker structure. The distributed MQTT broker architecture is expected to support new application services that cannot be supported by a conventional MQTT architecture. We have designed and implemented a distributed MQTT broker architecture based on the RPL protocol that has been widely used for IoT network. The experiment results show that the proposed MQTT broker architecture represents better publishing/subscribing latency and network stability than the conventional MQTT broker architecture.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.2929-2931
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• 1999

In this paper, an adaptive fuzzy inference and HCM(Hard C-Means) clustering method are used for on-line fuzzy modeling of nonlinear and complex system. Here HCM clustering method is utilized for determining the initial parameter of membership function of fuzzy premise rules and also avoiding overflow phenomenon during the identification of consequence parameters. To obtain the on-line model structure of fuzzy systems. we use the recursive least square method for the consequent parameter identification. And the proposed on-line identification algorithm is carried out and is evaluated for sewage treatment process system.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.2908-2910
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• 1999

In this paper, a fuzzy model is identified and optimized using the hybrid algorithm and HCM clustering method. Here, the hybrid algorithm is carried out as the structure combined with both a genetic algorithm and the improved complex method. The one is utilized for determining the initial parameters of membership function, the other for obtaining the fine parameters of membership function. HCM clustering algorithm is used to determine the confined region of initial parameters and also to avoid overflow phenomenon during auto-tuning of hybrid algorithm. And the standard least square method is used for the identification of optimum consequence parameters of fuzzy model. Two numerical examples are shown to evaluate the performance of the proposed model.

• Journal of Ocean Engineering and Technology
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• v.19 no.3
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• pp.18-24
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• 2005

Wave overtopping is one of the most important processes for the design of seawalls. The term "wave overtopping" is used here to refer to the processes where waves hit a sloping structure run up the slope and, if the crest level of the slope is lower than the highest run up level, overtop the structure. Wave overtopping is dependent on the processes associated with breaking wave. A numerical model based on Navier-Stokes equation and the Marker-density function for predicting wave overtopping of coastal structures is developed in this paper. In order to evaluate the present model, two simulations are tested. One is overflow without waves at vertical seawall, and the other is wave overtopping at sloping seawalls.