• Journal of Drive and Control
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• v.11 no.4
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• pp.46-52
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• 2014

This study suggests a small-sized screw decanter specialized for dredging sites. Generally, conventional screw decanters are composed of a cylinder and a cone. However, the suggested screw decanter simply has a cone based on a cone-type bowl structure. In this research, a commercial analysis tool is used to establish an optimal design for the bowl and the screw conveyor. Moreover, the base frame, where the main bearings that support the spindle of the bowl and the screw conveyor are installed, is optimally designed considering the weight of the rotating body and the deflection caused by the high centrifugal force. Furthermore, the natural frequency range of the spinning body, the bowl and the screw conveyor, is applied to this base frame; it is designed not to correspond to the resonance frequency range and achieves stability as a result. This study suggests an optimal design for the rotating body and the base frame of a screw decanter considering its vibration characteristics. Such a design will prevent overuse of materials and help to reduce the weight and volume-and the price-of a screw decanter.

• 연구논문집
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• s.31
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• pp.53-63
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• 2001

Numerical investigation based on the control-volume using finite-difference method has been made by the development of computer program in order to figure out the pattern of the flow field inside screw decanter. The typical flow pattern inside screw decanter is characterized by the two strong recirculation zones separated by the main stream from slurry discharge hole to exit. These recirculation regions and flow pattern are strongly influenced by the centrifugal force and the change of the value of slurry viscosities, that is,500, 1,000 and 3,000cp respectively. The wear of screw decanter appeared experimentally in two spots; one is near the circumferential area of the slurry discharge hole and the other is on the decanter blades at a certain height from the bottom to a different degree after the continuous long-term operation. These wears are partly explained by the flow pattern and the strong turbulence intensity near the recirculation attachment region.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.2_1
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• pp.169-176
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• 2022

Prognostics and health management (PHM) is recently converging throughout the industry, one of the trending issue is to detect abnormal conditions at decanter centrifuge during water treatment facilities. Wastewater treatment operation produces corrosive gas which results failures on attached sensors. This scenario causes frequent sensor replacement and requires highly qualified manager's visual inspection while replacing important parts such as bearings and screws. In this paper, we propose anomaly detection by measuring the vibration of the decanter centrifuge based on the video camera images. Measuring the vibration of the screw decanter by applying the optical flow technique, the amount of movement change of the corresponding pixel is measured and fed into the LST M model. As a result, it is possible to detect the normal/warning/dangerous state based on LSTM classification. In the future work, we aim to gather more abnormal data in order to increase the further accuracy so that it can be utilized in the field of industry.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.148-155
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• 2003

In this paper, based on the concept of solid particles' hovering problem the working formula for the channel design of a Decanter-type centrifuge were derived. The Shields' diagram and its curve-fitting formula were used in determining the criterion of particle size for the sediment. By using these formula the designer can determine the sectional configuration of the channel, such as the liquid depth, the normal pitch of the screw-blade arrangement and the bowl diameter.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.2
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• pp.60-70
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• 2000

The swine wastewater from slurry feedlot has been a social problem in Korea since the proper treatment is very difficult. Therefore, a practical study on the Solid-Liquid separation of swine wastewater from slurry feedlot was carried out as a pan of pretreatment for the successful biological treatment. The appropriate type of coagulant and optimum dosage were proposed for the most efficient Solid-Liquid separation and the best Solid-Liquid separation methods for different size of feedlot were determined through the tests with field-scaled Solid-Liquid separation equipment. The appropriate coagulant for the conditioning of dewatering property was E-851, which is a cationic polyelectrolyte made of polyacrylamide, and the optimum dosage was 0.24~0.6% of unit solids weight. Mesh Screen, Drum Screen, Cyclone Drum Filter, Screw Press, High-speed Screw Decanter, Low-speed Screw Decanter, and Dissolved Air Flotation Process had been investigated in this study. According to the results, the Screw Press was the best dewatering equipment for the small & medium size for feedlot and low-speed Screw Decanter was the best for the large size feedlot & public owned treatment facilities for the primary Solid-Liquid separation, and the most suitable secondary treatment process was DAF. On the other hand, reductions for the requirement of bulking agent and organic loading by Solid-Liquid separation process were 94.8% and 84.7%, respectively Therefore, the Solid-Liquid separation process must be required for the successful treatment of swine wastewater from slurry feedlot.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.7
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• pp.929-937
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• 2003

In general, the electric motor for driving the centrifuge of Decanter type is selected based on the power(starting power) necessary to start the bowl and the screw shaft. However the operation cost of the machine is dependent on the power needed at a steadily operating condition, including the power against the bearing friction and that for the sludge removal. In this paper, the formulation for the sludge-removal power is presented. Sample calculation for a specific design shows that the sludge-removal power is increased with the friction coefficient. It also reveals that the power is mainly dependent on the length of the screw blade rather than the beach angle. Further it is shown that the power increases in square of the rotational speed of the machine.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.3
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• pp.285-291
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• 2015

A centrifuge works on the principle that particles with different densities will separate at a rate proportional to the centrifugal force during high-speed rotation. Dense particles are quickly precipitated, and particles with relatively smaller densities are precipitated more slowly. A decanter-type centrifuge is used to remove, concentrate, and dehydrate sludge in a water treatment process. This is a core technology for measuring the sludge conveyance efficiency improvement. In this study, a smoothed particle hydro-dynamic analysis was performed for a decanter centrifuge used to convey sludge to evaluate the efficiency improvement. This analysis was applied to both the original centrifugal model and the design change model, which was a ball-plate rail model, to evaluate the sludge transfer efficiency.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.8
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• pp.879-885
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• 2008

A rotordynamic analysis was performed with a decant-type centrifuge, which is a kind of industrial centrifuge. The system is composed of screw rotor, bowl rotor, driving motors, gear box, and support rolling element bearings. These rotors have a rated speed of 4300 rpm, and were modeled utilizing a rotordynamic FE method for analysis, which was verified through 3-D FE analysis. Design goals are to achieve wide separation margins of lateral critical speeds, and favorable unbalance responses of the rotor in the operating range. Then, a complex analysis rotordynamic analysis of the system was carried out to evaluate its forward synchronous critical speeds and mode shapes, whirl natural frequencies, and unbalance responses under various balance grade. As a result of analysis, the rotordynamic analysis performed by separating a screw rotor and bowl rotor may cause an error in predicting critical speed of entire system. Therefore, the rotordynamic analysis of a coupled rotor combining a screw and bowl rotor must be performed in order to more accurately estimate dynamic characteristics of the decanter-type centrifuge as presented in this paper. Also, rolling element bearings with suitable stiffness should be selected to keep enough separation margin. In addition, in establishing balance grade of a screw and bowl rotor, ISO G2.5 balance grade is more recommended than ISO G6.3, in particular balancing correction of a screw rotor based on ISO G2.5 grade is strongly recommended.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.5
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• pp.571-577
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• 2012

In this study, a small movable batch treatment system for dredging soil deposited in a rain water tube is proposed; further, a vacuum silo sorting separation device with a vacuum silo, first-stage sorting separator, and conveyor is designed. The vacuum silo sorting separation device also consists of a storage tank, transferring screw, vacuum gate, screen bar, screen bar cleaner, and vacuum discharging device. In view of the fact that the flow of drawn air in the storage tank is a major factor influencing the sorting separation performance, the optimum shape of the tank is determined by CFD flow analysis. In addition, by using CAE structure analysis, the safety of a storage tank made of boards is examined. The specifications of the vacuum silo sorting separation device are determined by conducting mechanical and dynamic simulations of the driving mechanism of the vacuum silo sorting separation device through 3D-CAD modeling. Following this study, we will design a drum-screen-type second sorter, a decanter-type dehydration device, and waste water tank and pump as a secondary device. Further, on the basis of this design, we will construct a prototype model and carry out a field test.