• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.11
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• pp.1496-1502
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• 2002

An Altitude Engine Test Facility(AETF) was built at the Korea Aerospace Research Institute in October 1999 and has been being operated for altitude testing of gas turbine engines of 3,000 Ibf class or less. The AETF has been calibrated using several engines such as J69 of Teledyne Co. as a facility checkout engine. Uncertainty analyses on the air flow rate and thrust were performed using the test results, according to ASME PTC 19.1-1998. Several modifications on the facility and test method were made in order to improve the measurement uncertainty to a satisfactory level over the whole operating envelop. Spatial distributions of pressure and temperature were measured, sensors were substituted by more accurate ones, inlet duct was modified to refine the flow quality, and pressure control logic was revised to remove the cell pressure fluctuation. As a result, the uncertainty of the air flow measurement was improved by 0.1% over all the test conditions, and the net thrust measurement by up to 3%. The improved measurement uncertainties of air flow and thrust are 0.68～O.73% and 0.4～1.3%, respectively.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.25-27
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• 2003

In this paper the instantaneous thrust of a linear induction motor(LIM) with cage-type secondary is estimated by the line voltages and phase currents measurement when the LIM is fed by PWM inverter. The estimated thrust values according to various input frequencies are compared with the measured ones.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1599-1604
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• 2007

LIMs propelling the MAGLEV which has been developed in Korea have 3-series and 2-parallel connection, so that 6 LIMs per one vehicle are fed by one inverter. Thrust performance of the parallel-operated LIMs can be different from each other because of variant magnetic air gaps and electrical impedance. The thrust difference between the parallel LIMs cause a twist force on the vehicle. This paper proposes an algorithm to measure thrust of the parallel-operated LIMs. The method uses a digital signal processor(TMS320F2812), voltage and current sensors. As a result, thrust, flux and currents of the parallel-operated small LIMs which are manufactured in our laboratory are monitored by the developed measurement system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.358-362
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• 2005

An effective control of the axial thrust of a turbopump is one of the critical issues for its operational stability. In order to assure the stability of a turbopump-type fuel pump for a liquid rocket engine, an axial thrust measurement system was developed and a series of axial thrust tests were performed in water environment. In the tests, the axial thrust of the fuel pump at the design flowrate satisfied the axial force condition of the bearing of the pump. Also, it was found that by using orifices with different geometries in the secondary flow passage the overall axial thrust of the pump could be controlled.

• Journal of Electrical Engineering and Technology
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• v.2 no.1
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• pp.50-54
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• 2007

In this paper, a dual-servo type VCM (Voice Coil Motor) for the measuring of nano-level displacement and small thrust is proposed and developed. The shape of VCM for improving the resolution of displacement and ensuring a large displacement are presented. The FEM (finite element method) is utilized to analyze the characteristics of VCM that produces linear driving thrust and satisfies the thrust that the measurement system requires. The Prototype is fabricated and an experiment is performed in order to measure displacement. As a result of simulation and testing, the proposed VCM shows the applicable possibility for a nano-level measurement system.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.183-192
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• 1998

In this paper, we measure the back-EMF and the thrust of a linear brushless DC motor along the relative position between coils and magnets in various speed environments in order to obtain the back-EMF and the thrust as a function of a motor position. The measured back-EMF function and thrust function of the position differ from the analytical ones within 5%. The measured back-EMF and thrust function can, then, be employed in controlling the thrust ripple of the linear motor. Furthermore, to minimize the torque ripple of the linear motor, we suggest the design method to shape the back-EMF and thrust function of the linear motor.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.39-42
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• 2008

In the case of the general helicopter among rotorcraft, length of the rotor blade for thrust-generation is longer than that of fuselage and tail rotor is required in order to compensate moment of the fuselage. For those reasons, enough space for take-off and landing should be secured and an accessibility for building is low. Also, the accidents caused by tail rotor occur frequently. However, the case of counter-rotating has merits that tail rotor is unnecessary as well as length of the rotor blade can be shortened but has a weakness that the weight of body is increased. In the present study, aerodynamic force measurement on single rotor system equipped with NACA0012 airfoil, which has aspect ratio of 6 and chord length of 35.5 mm, was carried out. And measurement was conducted with blade which has a half size of the former blade by using single motor counter-rotating. Aerodynamic force measurement was acquired by using 6-component balances and coefficients of thrust and power were derived along the pitch angle varying from 0$^{\circ}$ to 90$^{\circ}$ with the increment of 10$^{\circ}$. Those aerodynamic force data will be utilized for the design and production of brand-new counter-rotating rotor blade system which has same thrust with single blade system and provides a good accessibility to building by reducing its blade length.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.574-577
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• 2012

Thrust measuring is one of the crucial factor to decide the performance of a liquid rocket engine when the engine development test, especially for the combustion chamber, is implemented. Calculating the thrust from a combustion pressure is used when direct measuring the thrust is impossible, but direct measuring the thrust is necessary and various methods for doing it more precisely should be considered. This paper introduces the preliminary design concept about the new thrust measurement system for the vertical firing test stand, which is introduced domestically for the first time, of a liquid rocket engine combustion chamber.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2147-2153
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• 2009

A Hybrid type Linear Pulse Motor(LPM) for low cost is designed as single side stator structure. The static and dynamic characteristics measurement systems are designed. Experimental measurement systems, which measure the static and dynamic characteristic of the LPM, are uggested for the prototype LPM. It becomes known the values of the thrust forces. Finally the microstep drive method is adopted to the drive of prototype LPM. The waveform difference is measured between the microstep method and rectangular wave. From the experimental results, it can be confirmed that the repetitive ripple of the thrust force of the prototype LPM are reduced by taking the microstep drive method.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.5
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• pp.31-39
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• 2016

This paper is studied on the effect of the bolt joint stiffness on the Thrust Measurement Stand(TMS). TMS is a test stand for thrust performance of the propulsion system, which depends on two factors: The $1^{st}$ is the parallel degree between directions of the thrust vector and action lines of the corresponding measuring load cells for the vector, and the $2^{nd}$ is the orthogonality between action lines of the measuring load cells. Therefore, it is essential to maintain the original shape of the TMS under operating conditions. In this paper, it is examined how the geometric tolerance of the bolt joints and threads of the load cell trains affect the performance of the TMS. Also, some techniques to overcome related problems are proposed.