• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.1
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• pp.34-42
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• 2011

It's been reported that the global warming effect has invoked the ever increasing typhoon intensity and long-term sea level rise which jointly cause severe wave overtopping over breakwaters or shore dykes. A simple measure to cope with this undesirable change may be just to increase the crest height of the dykes and breakwaters. This is surely effective to prevent wave overtopping, but it also decreases the seaward visibility of coastal waterfront. In this paper, a dynamic deformable rubber membrane parapet which not only reduces wave overtopping in storm period but also secures seascapes in normal days is presented. Several optimal configurations of the parapet are proposed. Through numerical analyses using a nonlinear finite element model and hydraulic experiments, the air controlled expansion and contraction of the parapets, their behavior against wave overtopping and structural stability are investigated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.2
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• pp.183-190
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• 2015

An ejector is a type of non-powered pump that is used to supply a secondary flow via the ejection of a primary flow. It is utilized in many industrial fields, and is used for fueling the vehicle because of less failures and simple structure. Since most of ejectors in industry are gas-to-gas and liquid to gas ejector, many research activities have been reported in optimization of gas ejector. On the other hand, the liquid ejector is also applied in many industry but few research has been reported. The liquid ejector occurs cavitation, and it causes damage of parts. Cavitation has bees observed at the nozzle throat at the specified pressure. In this study, a two-dimensional axisymmetric simulation of a liquid-liquid ejector was carried out using five different parameters. The angle of the nozzle plays an important role in the cavitation of a liquid ejector, and the performance characteristics of the flow ratio showed that an angle of $35^{\circ}$ was the most advantageous. The simulation results showed that the performance of the liquid ejector and the cavitation effect have to be considered simultaneously.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.3
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• pp.136-143
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• 2006

The study was carried out to evaluate odor emission during storage time and quality of liquid slurry fertilizer along with three storage container types installed at farmer's fields in Cheorwon. Liquid slurry manure stored in the liquid-circulated or the air-injected tank was very homogeneous in concentration of nutritional elements because of well mixing operation, while nutritional concentration of the manure stored in the non-treated tank was significantly different from top to bottom in the tank, which may bring about partially irregular growth of plant after its application. The potential capacity of offensive odor emitted from liquid slurry manure stored in the liquid-circulated or the air-injected tank was much lower than that emitted from manure stored in the non-treated tank. Low potential capacity may less emit offensive odor after application of piggery liquid slurry on the field. The efficiency in oder to reduce odor emission from liquid manure was slightly higher in the liquid-circulated tank than the air-injected tank