• Journal of Korean Society of Water and Wastewater
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• v.24 no.4
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• pp.377-386
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• 2010

To identify operating parameters of the up-flow filtering system, which is available to discharge filtering residue after the rain, developed for treatment of urban storm runoff, lab scale test was carried out. Removal efficiency of SS was 68.7%, 62.2%, and 58.6% at the area roading rate of 2.46m/h, 4.68m/h, and 10m/h, respectively, filtering device is desirable to operate at the lower than 4.68m/h of area roading rate to get higher level of 60% SS removal efficiency. The removal efficiency of SS was 57.1% ~ 68.7% at the raw water SS of 100mg/L ~ 600mg/L, and the SS in treated water was maintained at the constant level through the elapsed time. It is indicate that filtering device can guarantee a certain level of effluent water quality at various raw water quality. The removal efficiency of SS to the depth of filter media was 68.3%, 78.6% at the filter depth of 10 cm, 20cm respectively. The final treated water quality was showed 30.2mg/L of CODMn, 1.60mg/L of TN and 0.25mg/L of TP. The average removal efficiencies by filtering device developed in this research were recorded slightly lower levels than other research. The main reason of these results were the first, the filter depth of the media used in this test was shallow, the second, the kind of filter media in discharge port of residue. More research to kind of filter media, filter packing rate, select of media for residue discharge port should be go on to produce optimum operating condition. The result of this study would be valuable for the application of filtration device to control of urban storm water.

• Journal of Korean Society of Rural Planning
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• v.25 no.4
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• pp.27-33
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• 2019

Agricultural water for crops are faced with the need to improve the use efficiency due to the impact of climate change. Water productivity (WP) is known as a good indicator for assessing resources efficiency. This study was conducted to assess WP of rice and potential water consumption (PWC) as new indicator for water use efficiency assessment. The average of WP was 0.7 kg/㎥, and Jeonbuk had the highest WP as 0.83 kg/㎥. Kangwon and Kyungbuk had the lowest WP as 0.59 kg/㎥. PWC showed the same trend because of rice consumption per capita, but Total PWC considering population living in each province showed the different trend with PWC. Every year, the changing patterns of WP was increasing little by little, and the patterns of PWC was decreasing greatly than WP. These results mean that WP has been slowly improved through breed development and irrigation techniques, and PWC was affected by reduced rice consumption and WP increasing. PWC could also be useful as an indicator to compare the water use efficiency between provinces or nations.

• Water for future
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• v.29 no.1
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• pp.213-220
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• 1996

This paper presents an experimental study on the discharge head of Cherepnov water lifter that was continuously operated with the aid of the siphon. The energy used by the Cherepnov water lifter is derived from the potential energy ofthe water itself. The lifter consists of three interconnected tanks and five pipes, one of which is open and two others are hermetically sealed. The effects of varying operating parameters such as the tank and pipe size, the ratio between head of discharge and drop height were analyzed. As a result, factors that can maximize the efficiency and increase the average delivery rate were indentified. When the ratio between head of discharge and drop height is about 0.5, the efficiency of Cherepnov water lifter is maximized. In order to design the efficient Cherepnov water lifter, the discharge head of the Cherepnov water lifter should be assigned to be twice as much as the drop height. The effect of tank size on the efficiency is less than 5%, while the effect of the pipe size is not negligible. The larger the pipe size is, the more the efficiency increases.

• Journal of the Korea Furniture Society
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• v.19 no.3
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• pp.172-179
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• 2008

The objective of this study was to investigate the influence of the water repellents' treatment on the water absorptivity and the dimensional stability of Korean red pine wood(Pinus densiflora). The alkylketene dimer(AKD), fluororesin emulsion(Wood-seal, WS), and paraffin wax emulsions(PW25, PW40, and PW1200) were used as water repellents. PW40 and WS were proved as excellent water repellents for pine wood, because the samples treated with these agents showed high contact angles and large reduction in water absorptivities. Also, the dimensional stability(antiswelling efficiency) of pine wood was considerably improved by water repellents treatments, such as PW40 and WS at the pressure of 2MPa. The water repellent treated woods with WS, PW40, and PW1200 at the pressure of 2MPa were relatively stable to the wet-dry cyclic leaching test.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1427-1432
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• 2008

This paper describes the locomotion of a water jumping robot which attempts to emulate the fishing spider’s ability to jump on the water surface. While previous studies of the robots mimicking arthropods living on water were focused on recreating their horizontal skating motions, here we aim to achieve a vertical jumping motion. The robot jumps by pushing the water surface with rapidly released legs which were initially bent. The motion is triggered with a latch driven by the shape memory alloy actuator. The robot is capable of jumping to the maximum height of 26mm. Jumping efficiency, defined the maximum jumping height on water over the maximum jumping height on rigid ground, is 0.26 This work represents a first step toward robots that can locomote on water with superior versatility including skating and jumping.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.1
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• pp.67-74
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• 2016

The demand of environmental friendly packaging materials such as pulp mold has been increased. The application of the oil palm biomass, EFB (Empty Fruit Bunch) fiber as natural raw materials to the pulp mold could increase the usability of the pulp mold by the reduced production cost brought from the relatively low cost of EFB. The effects of the EFB(Empty Fruit Bunch) fibers on the properties of pulp mold and on the process efficiency were evaluated in this study. The pulp mold samples were prepared with mixture ONP (Old news paper) and EFB by using laboratory wet pulp molder. The changes in the drying efficiency were measured with the changes in the solid contents of pulp mold samples during drying process. The efficiency of the surface coating treatment on the pulp mold depending on the condition of the pulp mold samples were also evaluated in order to improve the water resistance properties of pulp mold. The addition of EFB increased the drying efficiency by providing the bulkier structure and the higher water contact angle, which indicated the better water resistance properties. The water resistance were improved by the surface coating treatments and the application of surface coating on the pulp mold at the higher moisture contents resulted in the higher improvement in the water resistance. The bulkier structure originated from the application of EFB fiber reduced the effects of the surface coating, which could be overcome by the control of surface coating process.

• Journal of Korean Society of Water and Wastewater
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• v.38 no.4
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• pp.233-242
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• 2024

This study evaluates the potential of various coagulants to enhance the efficiency of total phosphorus removal facilities in a sewage treatment plant. After analyzing the existing water quality conditions of the sewage treatment plant, the coagulant of poly aluminium chloride was experimentally applied to measure its effectiveness. In this process, the use of poly aluminium chloride and polymers in various ratios was explored to identify the optimal combination of coagulants. The experimental results showed that the a coagulants combination demonstrated higher treatment efficiency compared to exclusive use of large amounts of poly aluminium chloride methods. Particularly, the appropriate combination of poly aluminium chloride and polymers played a significant role. The optimal coagulant combination derived from the experiments was applied in a micro flotation method of real sewage treatment plant to evaluate its effectiveness. This study presents a new methodology that can contribute to enhancing the efficiency of sewage treatment processes and reducing environmental pollution. This research is expected to make an important contribution to improving to phosphorus remove efficiency of similar wastewater treatment plant and reducing the ecological impact from using coagulants in the future.

• International Journal of Fluid Machinery and Systems
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• v.6 no.1
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• pp.1-10
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• 2013

Jet pump is one type of artificial lifts and is used when depth and deviation of producing wells increases and pressure depletion occurs. In the present study, numerical analysis has been carried out to analyze the flow behavior and find the performance of the jet pump. Reynolds-averaged Navier Stokes equations were solved and k-${\varepsilon}$ turbulence model was used for simulations. Water and light oil as primary fluids were used to pump water, light oil and heavy oil. The ratios of area and length to diameter of the mixing tube were considered as design parameters. The pump efficiency was considered to maximize for the downhole conditions. It was found that the increase in viscosity and density of the secondary fluid reduced efficiency of the system. Water as primary fluid produced better efficiency than the light oil. It was also found that the longer throat length increased efficiency upto 40% if light oil was used as primary fluid and secondary fluid viscosity was 350 cSt.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.9
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• pp.977-982
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• 2013

Blades of wind energy plants are exposed to external shocks or internal cracks during operation. Furthermore, the blade surfaces can be contaminated by substances such as dust, blood of birds, salt or insects which can decrease the electricity generation efficiency significantly. For this reason, many blade cleaning companies started to appear and a variety of methods for cleaning were suggested. Despite these diverse methods, there has been no study to investigate how effectively to clean the substances in quantitative manner. In this paper, the cleaning efficiency of two rotor blade cleaning methods, brush and water-jet, is examined through experiments by changing operating parameters. Then, the optimal operating conditions for both methods are derived.

• Journal of the Korean Society of Industry Convergence
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• v.13 no.1
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• pp.31-39
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• 2010

An exergy analysis is carried out for the regenerative gas turbine cycle which has a potential of enhanced thermal efficiency and specific power owing to the more possible water injection than that of inlet fogging under the ambient conditions. Using the analysis model in the view of the second law of thermodynamics, the effects of pressure ratio, water injection ratio and ambient temperature are investigated on the performance of the system such as exergetic efficiency, heat recovery ratio of recuperator, exergy destruction or loss ratios, and on the optimal conditions for maximum exergy efficiency. The results of computation for the typical cases show that the regenerative gas turbine system with afterfogging can make a notable enhancement of exergy efficiency.