• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.902-909
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• 2006

In this study, three-dimensional rotordynamic analyses have been conducted using equivalent beam, hybrid and fun three-dimensional models. The Present computational method is based on the general finite element method with rotating gyroscopic effects of a rotor system. General purpose commercial finite element code, SAMCEF which includes practical rotordynamics module with various types of rotor analysis methods and bearing elements is applied. For the purpose of numerical verification, comparison study for a benchmark rotor model with support bearings is performed first. Detailed finite element models based on three different modeling concepts are constructed and then computational analyses are conducted for the realistic and complex three-dimensional rotor system. The results for rotor stability and mass unbalance response are presented and compared with the experimental vibration test conducted in this study.

• Journal of Animal Environmental Science
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• v.6 no.1
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• pp.37-44
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• 2000

A new hose slurry spreader with improved spreading uniformity is developed to distribute the slurrynear to the soil surface and to reduce odor problems. The precision of distributed slurry was investigated using 3 types of slurry and found to be dependent on the rotor speed. For the solid matter separated fluid containing 0.1% of dry matter rotor speed of 150 rpm showed best uniformity with CV of 10% In the case of slurry from dairy cattle which contains 8.2% of dry matter high rotor speed of 330 rpm showed best result with CV of 7.2% Also swine slurry which has a 13.6% of dry matter content showed the best result of 8.1% CV at the high rotor speed of 250rpm. A high rotor speed generates enough pressure in the central distributor and as a result uniform distribution of slurry can be achieved. In conclusion it is highly recommended rotor speed of 300 rpm to get the best performance.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.752-753
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• 2006

Oil Pump rotor is essential parts for automobile and, it is consisted of drive rotor and driven rotor in general. These parts are requested different properties according to environment. There are 2 types of Oil Pump rotor according to its usage. One is used for electric system, and the other is used for shaft-driven system. Especially, high precision and functionality is required in electric pump, and cost reduction is required in shaft-drive pump without slowing down its performance. This paper is mainly describing about the non-machine treated shaft-drive pump, based on the trial sample producing process.

• Current Industrial and Technological Trends in Aerospace
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• v.8 no.1
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• pp.118-130
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• 2010

In this paper, it is described the current technology status of bearingless rotor hub system for helicopter which is one of major rotor hub system. First, the advantages and disadvantages of major helicopter rotor hub system are described and compared each other. The unique characteristics of bearingless rotor hub system are described compared to other types of rotor hub systems. Next, the main function, role and characteristics of the sub-components of bearingless rotor hub system are described. Furtherly, recent helicopters which adopt this bearingless rotor hub system are described and introduced.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.101-103
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• 2003

This paper deals with field distributions in high speed motor with two different types of diametrically magnetized PM rotor, one is that rotor is consisted of PM and shaft, the other is that rotor has only PM. In case of high speed motor with rotor consisted of PM and shaft, this paper predicts field distributions in high speed motor according to the quality of shaft. The magnetic field solutions are derived analytically in terms of vector potential and 2-D polar coordinate system. The results are shown in good conformity with those obtained from the commonly used finite element method.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.9-11
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• 2003

This paper deals with the comparison of rotor eddy current losses In two types of permanent magnet high-speed machines. The analytical method and two dimensional finite element analysis have been used to evaluate the rotor eddy current loss with the rotor magnetization Pattern. It is shown that the Halbach array produce rotor loss less than parallel magnetization.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.10
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• pp.687-694
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• 2007

Cycle simulation is peformed for two types of the desiccant cooling system incorporating a regenerative evaporative cooler. The cooling capacity and COP are evaluated at various effectiveness values of the regenerative evaporative cooler, the desiccant rotor and the sensible heat exchanger. As either of the effectiveness of the regenerative evaporative cooler or the humidity effectiveness of the desiccant rotor increases, both the cooling capacity and COP increase, but the enthalpy leak ratio gives the opposite effect on the system performance. It is found that COP of cycle A mainly depends on the humidity effectiveness of the desiccant rotor, while for cycle B enthalpy leak ratio of desiccant rotor has the major impact on COP. The effect of the sensible heat exchanger on the cooling capacity is small about 1/10 compared with those of other components.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.3
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• pp.103-107
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• 2004

Recently, greater attention has been paid to the high-speed generator for its many merits, such as ease of installation, high efficiency and high power density. However, due to their high fundamental frequency, careful consideration needs to be given to both electromagnetic and mechanical design issues. This paper deals with the comparison of two types of permanent magnet high-speed machines. Specifically, the effect of the permanent magnet magnetization pattern on the rotor losses is investigated. On the basis of analytical field analysis and the 2-D finite element method, this paper predicts the flux harmonics and rotor losses under the no-load condition. It is shown that the Halbach magnetization is superior to parallel magnetization in terms of producing rotor losses.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.56 no.1
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• pp.51-55
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• 2007

In this paper, a portable rotor bar fault diagnosis system for small 3 phase induction motors is suggested. For portable real-tine diagnosis system, an USB-DAQ board for collecting the 3 phase current data, three current probes, and a notebook computer are used. The LabVIEW graphical language is used for filtering, analysis, storing, and monitoring the current data. The three phase stator current are filtered and transformed to frequency level by FIT. An analysis window programed by LabVIEW is located in front panel to show the FIT results and this suggested window has a zooming function to detect the fault feature more easily near the feature frequency range which is varying by the slip frequency. To show the possibility of portable rotor bar diagnosis system, three types(healthy, one rotor bar fault, two rotor bar fault) of rotor bar are intentionally prepared and compared by the suggested window of front panel. Experimental results are shown that a suggested diagnosis system is applicable to portable diagnosis system and the rotor bar fault is detected by the frequency window in front panel programed in LabVIEW graphical language.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.5-8
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• 2008

In this paper, the effect of turbine shape on the flow characteristics and performance of dental air turbine handpiece were studied using CFD. Computations have been performed for many different cases of the angle between the center-line of nozzle and turbine rotor by using frozen rotor method that one of steady-state method. The characteristics of turbine rotor for three different types (flat, concave, gull) were analyzed. Additionally, the turbine rotor of gull type that has better performance than others was computed for other reflected angles.