• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.4
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• pp.400-406
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• 2017

The model used in this study was reversed to analyze the cause of excessive damage that occurred inside the rotating system and pipe system of a centrifugal-type seawater pump on a ship. For this purpose, internal flow analysis on a cooling seawater pump was performed using CFD. As a result, the shape and boundary conditions of the target pump were set by reverse engineering, and pump efficiency at a design operating point of $125m^3/h$ was calculated as 85.3 % with a head of 32.0 m. The maximum efficiency point of the target pump was estimated to be 86.2 % at $150m^3/h$, but this differed from the actual operating point. At $112.5m^3/h$, which was the lowest flow point, flow was unstable due to the characteristics of the low flow point and analysis convergence was not good. The purpose of this study was to clarify the cause of ongoing cavitation in seawater pumps and piping systems in operation. Future research will be needed to clarify causes for pipe systems in the future by performing calculations for the total piping system of an inlet and outlet, in addition to measuring the flow rate of each branch pipe.

• Journal of the Korean GEO-environmental Society
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• v.15 no.3
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• pp.49-55
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• 2014

Characteristics of sedimentation of dredged soil is depended on the field condition and characteristics of dredged soil because dredged fill ground was formed by various field condition, sedimentation and self-weight consolidation process of dredged soil. Dredged fill ground is formed as separated sedimentary layer by characteristics of dredged soil. Therefore, it requires some special test method to consider a various field condition, characteristics of sedimentation and self-weight consolidation of dredged soil. In this study, in order to identify the characteristics of sedimentation of dredged soil with disposing velocity geo-centrifuge test and laser particle size analyzer were performed. As a results, river and mixed dredged soil show the separation sedimentation by soil particle size. And sedimentation of clayey dredged soil is parallel to the bottom surface of dredged fill space.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.3
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• pp.70-76
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• 2022

Recently, the demand for ultra-precision processing has increased owing to the increase in the demand for high-performance ultra-precision optical parts in the fields of information technology (IT), bio, healthcare, aerospace, and future automobiles. In this study, a performance improvement of a multi-stage pump was achieved by improving the pump casing structure rather than using the existing performance improvement method. To verify the performance improvement, the CFD analysis reliability of the existing pump, Pump A, was verified using the FLUENT app in the analysis software ANSYS, and the pump casing was improved through the verified CFD analysis of Pump B. Therefore, we want to analyze the performance improvement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.343.1-343
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• 2002

In this study, the increasing gear boxes for the high speed vertical in-line centrifugal pump are developed through rotor dynamic analysis. The developed increasing gear boxes are two kinds fur 18000rpm and 25000rpm at the output shaft. The gear sets suitable for high speed and high load are manufactured by investigating AGMA bending strength and AGMA surface strength severely. The rotor dynamic analysis on gear sets and bearings is performed in order to avoid the critical speeds and other troubles. As a result of study, the two increasing gear boxes for the high speed vertical in-line centrifugal pump are designed and maunfactured.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.20-27
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• 2012

Mechanical seals are one of main components of high speed centrifugal pumps. So, it is very important to detect the faults (scratch, notch, indentation, wear) of mechanical seals since the damage of seal can cause a critical failures or accidents of machinery system. In the past, many researchers mainly performed to detect the seal fault using the time signals measured from sensors. Recently, studies are focused on the development of on-line real time monitoring system. But study on the feature parameters used for fault detection of mechanical seals has a little been performed. In this paper, we showed feature parameters extracted from accelerated and acoustic signals by using the discrete wavelet transform (DWT), alpha coefficient, statistical parameters. And also verified the possibility for fault detection of mechanical seal.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.531-534
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• 2006

This study is concerned with radial turbine design and performance improvement of a turbo generator system, which is used for maximizing performance of a 250kW MCFC fuel cell system. A preliminary design of a radial turbine has been performed under the thermodynamic and fluid-dynamic conditions determined by a cycle analysis of the MCFC BOP system. Basic demensions are determined by a meanline analysis and calculation of radial variation at the exit of the turbine. The turbine impeller is designed and modified by iterative processes of three dimensional flow analysis.

• Journal of Chest Surgery
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• v.37 no.1
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• pp.108-111
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• 2004

Reoperation on the recurrent aortic aneurysm adjuvent to sternum remains a challenging problem in regard to the risk of the massive hemorrhage at the time of resternotomy resulting from inadvertent entry into the aneurysmal sac. The cardiopulmonary bypass technique of femoral cannulation and deep hypothermic circulatory arrest can provide a safe resternotomy. The left ventricle is likely to distend due to lack of contraction with ventricular fibrillation during core cooling. To prevent ventricular distention during core cooling, sufficient venous drainage is mandatory, We report a technique in which deep hypothermic circulatory arrest is achieved before resternotomy without left ventricular distention by active venous drainage using centrifugal pump.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.49-58
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• 2009

This paper presents the vector control of single phase induction motor(SPIM) to operate water pumping system using PV system with a maximum power point tracking(MPPT). The water pumping system uses a variable speed SPIM driven a centrifugal pump by field oriented control(FOC) inverter. The MPPT using a DC-DC converter controlled the duty cycle to track maximum power from PV under different insolation conditions. The duty cycle directly relate with a flux producing current control($i_{ds}$). The FOC inverter uses a current control voltage source inverter(CC-VSI). The simulation results are shown that the characteristics and performance of drive system, which varies as each conditions of light by expresses in voltage($V_{dq}$), current($I_{dq}$), speed of motor and torque.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.245-246
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• 1998

AMB(Active Magnetic Bearing) systems are popularly used in various areas. In biomedical engineering applications it is a key part of magnetically suspended rotary blood pumps. The special advantage of AMBs is that they enable the rotor to revolve with no physical contact and provide rotary blood pumps with better performances such as low hemolysis level. Fundamentally, AMB systems consist of three parts, proximity sensors for distance detection, microprocessor for control algorithm and power amplifiers for actuating electromagnets. We have developed an inductive type proximity sensor with satisfactory characteristics that can be used in AMB systems. Frequency response was flat at least up to 10 kHz and sensitivity, resolution$(>5{\mu}m)$ and sensing range(<5mm) of the sensor could be adjustable for various purposes. The characteristics of the completed model showed to have satisfactory behaviors compared with the commercially available ones that already appeared to have reliable behaviors in AMB systems.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.2
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• pp.101-106
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• 2017

The chemical mechanical planarization (CMP) process combines the chemical effect of slurry with the mechanical effect of abrasive (slurry)-wafer-pads The slurry delivery system has a notable effect on polishing results, because the slurry distribution is changed by the supply method. Thus, the investigation of slurry pumps and nozzles with regard to the slurry delivery system becomes important. This paper investigated the effect of a centrifugal slurry pump on a spray nozzle system in terms of uniform slurry supply under a rotating copper (Cu) wafer, based on experimental results and computational fluid dynamics (CFD). In conventional tools, the slurry is unevenly and discontinuously supplied to the pad, due to a pulsed flow caused by the peristaltic pump and distributed in a narrow area by the tube nozzle. Adopting the proposed slurry delivery system provides a higher uniformity and lowered shear stress than usual methods. Therefore, the newly developed slurry delivery system can improve the CMP performance.