• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.837-846
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• 2006

In this paper, axial flow fans which applied at coal-thermal power plant(500[MW]) cause a unique phenomenon called 'Stall' under normal operation and this causes abnormal operation and damages the blades. In order to prevent these abnormal operation, this study estimates the reliability of new system which is applying control logic on each parameter with existing black-box-type by field test.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.1047-1050
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• 2010

축류팬(axial fan)은 냉장고, 에어컨 등 가전제품 뿐 아니라, 자동차, 중장비 등에 가장 널리 사용되는 팬의 형태로 제품의 성능과 소음에 많은 영향을 미치는 요소이다. 그러나 설계, 목업(mock-up)개발, 풍동실험 등의 시간과 비용적인 면에서 비효율적인 방법을 통해 개발이 이루어지고 있다. 따라서 범용으로 사용가능한 팬 설계 프로그램과 설계 인자의 입력만으로도 성능을 예측하여 개발에 소요되는 시간과 비용을 줄일 수 있는 시스템의 개발이 필요하다. 본 연구에서는 슈퍼컴퓨터를 활용하여 축류팬 형상변수의 변화에 대한 성능과 소음을 미리 해석한 후 그 결과를 지식형 데이터베이스로 저장하고, 팬 자동설계 시스템과 결합한다. 즉, 축류팬 설계 변수를 입력하면 팬의 형상을 CAD 파일로 자동 생성할 뿐 아니라, 지식형 데이터베이스을 기반으로 하는 데이터 마이닝 기법을 이용하여 해당 모델의 성능과 소음을 예측한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.12
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• pp.76-82
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• 2005

An experimental study on an axial-type micro turbine which consists of maximum 6 stages is conducted to measure aerodynamic characteristics on each stage. This turbine has a 2.0 flow coefficient, 3.25 loading coefficient and 25.8mm mean diameter. The solidity of stators and rotors is within a 0.67~0.75, and the off-design performance is measured by changing the load after adjusting the mass flowrate and the total pressure to constant at inlet. A maximum specific output power of 2kW/kg/sec is obtained in one stage, but the increment of the specific output power with increasing stages is alleviated. In case of torque, the increment of the torque maintains to constant at low RPM region, but its increment become dull at high RPM region. The efficiency of the micro turbine becomes low because the tip gap effect is great due to the small blade, but it could be improved by increasing the stages.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.4
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• pp.10-18
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• 2007

A tested micro axial-type turbine consists of two stages and its mean radius of rotor flow passage is 8.4 mm. This turbine could be applied to a driver of micro power system, and its rotational speed in the unloaded state reaches to 100,000 RPM. The performance of this system is sensitive depending on the blade angles of the rotor and stator because it is operated in a low partial admission rate, so a performance test is conducted through measuring the specific output power and the net specific output torque with various blade angles on the nozzle, stator and rotor. The experimental results show that the net specific output torque is varied by 15% by changing the rotor blade angle, and the optimal incidence angle is about $10.3^{\circ}$.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.6
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• pp.21-29
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• 2008

Performance characteristics on a partially admitted small axial-type turbine are experimentally studied with changing design parameters, such as exit flow angles at the nozzle and solidities at the rotor. The tested turbine consists of a single-stage and its mean radius is 35 mm. In this experiment, three different solidities and four different nozzle flow angles are applied to find the optimal design parameter. For a comparison of the turbine performance, the net specific output powers are evaluated. For a 3.4% partial admission rate, the best performance is obtained when the rotor solidity is at 2.18, which is increased to 74% compared to the solidity at full admission.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.3
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• pp.10-17
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• 2005

A performance prediction model is developed for partially admitted axial-type turbines. Losses generated within the turbine are classified to the windage loss, expansion loss and mixing loss. The developed loss model is compared with an experimental result. The results predicted with the developed model agree well with the experimental results than those predicted with several other models because this model considers three different kinds of losses. Moreover, this model predicts well the performance even the partial admission is changed. So, this model could be applied to predict the performance of partially admitted axial turbine and it has a high accurate performance.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.359-364
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• 2005

Centrifugal pump shows the strongest secondary flow. Wake is formed near pressure surface close to hub at impeller exit for centrifugal pump impeller. Pressure gradient drives secondary flow in the inducer region, while in the remaining region the following sources drive together: > Pressure gradient > Coriolis force Low-momentum fluid near suction surface hub moves toward pressure surface hub in mixed-flow pump impeller. Tip leakage vortex dominate secondary flow in axial-flow pump impeller. Tip leakage vortex dominate secondary flow in axial-flow in axial-flow pump impeller

• Journal of Biomedical Engineering Research
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• v.19 no.1
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• pp.33-38
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• 1998

The intracardiac axial flow pump has been developed This device has several advantages: it fits well anatomically, its blood-contacting surface is small, and it is implanted as easily as an artificial heart valve replacement. The axial flow pump consists of an impeller and a motor, both of which are encased in a housing. Two types of impeller with 4 vanes and 6 vanes are used. Sealing of the motor shaft is achieved by means of a ferrofluidic seal. A flow of 5$\ell$/min was obtained at a differential pressure of 100mmHg with a motor speed of 7091rpm with the 4-vane impeller and 6402rpm with the 6-vane impeller. Sealing was kept against a pressure of 150mmHg at 7000rpm with the 4-vane impeller and 6402rpm with the 6-vane impeller. Sealing was kept against a pressure of 150mmHg at 7000rpm over 24 hours. The index of hemolysis was 0.056 with the 4-vane impeller and 0.214 with the 6-vane impeller. The intracardiac axial flow pump is a very promising circulatory support.

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.353-362
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• 2000

Minimization of hemolysis is one of the key factors for successful axial flow blood pumps. It is, however, difficult to estimate the hemolytic performance of axial flow blood pumps without experiments. Instead, the Computational Fluid Dynamics(CFD) analysis enables the prediction of hemolysis. Three-dimensional fluid dynamics of axial flow pumps with different impellers were analyzed using the CFD software, FLOTRAN. The turbulence model k-$\varepsilon$ was used. The changes in turbulent kinetic energy applied to each particle (red blood cell) flowing through the pumps were computed and displayed by the particle trace method (particle spacing of 10 msec). Also, the Reynolds shear stress was calculated from the turbulent kinetic energy. The shear stress was higher behind the impellers than elsewhere. The CFD analysis could predict in vitro results of hemolysis and also the areas where hemolysis occurred. The CFD analysis was found to be a useful tool for designing less hemolytic rotary blood pumps.

• Proceedings of the KAIS Fall Conference
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• 2006.11a
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• pp.191-194
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• 2006

500MW급 대용량 보일러 통풍계통의 Fan Stall 감시 장치는 Fan 이상 발생시 Fan을 보호하기 위하여 정지시키는 기능을 한다. 그러나 Fan Stall 감시 장치의 빈번한 고장으로 신뢰성이 저하되고 운전에 영향을 미치므로 이것을 DCS Logic으로 구성하여 신뢰성을 향상시켰다.