• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.1-6
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• 2004

One of the mechanical system engineer's tasks of satellite design and development is to make the control plan, keep track and estimate the characteristics of system mass properties. As the design phases are going on, mass properties related activities also transit as like a data collection, system mass property estimation and measurement. Fidelity of mass properties database should be confirmed through measurement test. In this paper the control plan and estimation of system mass properties are explained by the actual data and experience of the development of satellite and the fidelity of mass properties database was confirmed through measurement test.

• Journal of Astronomy and Space Sciences
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• v.20 no.4
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• pp.375-382
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• 2003

One of the mechanical system engineer's tasks of a satellite design and development is to make the control plan, keep track and estimate the characteristics of system mass properties. As the design phases are go, mass properties related activities also transit as like a data collection, system mass property estimation and measurement. Fidelity of mass properties database should be confirmed through measurement test. In this paper the control plan and estimation of system mass properties are explained by the actual data and experience of the development of satellite and the fidelity of mass properties database was confirmed through measurement test.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.115-120
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• 2002

The rigid body properties of a structure may be estimated easily if the mass-line of the structure could be taken exactly. However, the exact mass-line may be hard to be obtained exactly in experiments. The mass line value can be read from the mass line in frequency response function. However, the mass lines in the frequency response function sometimes show the fluctuation with frequency, and it cannot be read correctly. In this paper, the wavelet transform is applied to obtain the good mass line value. The mass line calculated by using wavelet transform has unique value and showed in the range of fluctuated values of frequency response function. The rigid body properties obtained by wavelet transform also showed better results than those by fourier transform.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.9
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• pp.725-730
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• 2002

The rigid body properties of a structure may be estimated easily if the mass-line of the structure could be taken exactly. However, the exact mass-line nay be hard to be obtained exactly in experiments. The mass line value can be read from the mass line in frequency response function. However, the mass lines in the frequency response function sometimes show the fluctuation with frequency, and it cannot be read correctly. In this paper, the wavelet transform is applied to obtain the good mass line value. The mass line calculated by using wavelet transform has unique value and showed in the range of fluctuated values of frequency response function. The rigid body properties obtained by wavelet transform also showed better results than those by fourier transform.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.317-322
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• 2002

There are many researches to identify the rigid body properties from the mass-line obtained by impact hammer testing. The correct rigid body properties of the structure may be estimated if the mass-line of the structure could be obtained exactly. When the structure is mounted by elastic materials, the mass-line cannot be read correctly from the impulse response spectrum. The reason is due to the effects of rigid body modes of mounted structure. In this paper, the effects of rigid body modes of mounted structure to the mass-line are discussed and the method to remove these effects is also presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.336.2-336
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• 2002

There are many researches to identify the rigid body properties from the mass-line obtained by impact hammer testing. The correct rigid body properties of the structure may be estimated if the mass-line of the structure could be obtained exactly. When the structure is mounted by elastic materials, the mass-line cannot be read correctly from the impulse response spectrum. The reason is due to the effects of rigid body modes of mounted structure. (omitted)

• Journal of Astronomy and Space Sciences
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• v.16 no.1
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• pp.31-40
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• 1999

With a total 761 contact binary systems in Svechnikov & Kuznetsova(1990)'s catalogue, their physical properties by the mass ratio are investigated - for the early CE type with a common radiative envelope and the late CW type with a common convective envelope. It is found that the early CE type shows a higher temperature difference($\mid$$DeltaT$$\mid$) between the primary and secondary components, and also longer period, than the late CW type. The mass ratio of the CW type are distributed in period, than the late CW type. The mass ratio of the CW type are distributed in smaller ranges, from 0.3 to 0.7, than the CE type. Further, the relation between mass ratio and luminosity for the CW type shows a well-defined linear relation, such as ratio and luminosity for the CW type shows a well-defined linear relation, such as $L_2/L_1$ = 0.01 = 0.89q. In the mass ratio-radii relation, it is confirmed that the physical difference of the CE and CW types is a result of the secondary radius. A new mass ratio-radii relation for the CW type is suggested for both the total radius $({gamma}_1/{gamma}_2$ and the radius ratio $({gamma}_2/{gamma}_1$, respectively.

• Journal of Astronomy and Space Sciences
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• v.17 no.2
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• pp.151-162
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• 2000

The general properties of the NCBs, divided into A and F types according to their spectral types, have been presented. The evolutionary status of the F type near-contact binaries are closer to that of the contact systems, i.e., W UMa type binaries, if it is assumed that the evolution of the NCBs is governed by the thermal relaxation oscillation theory. The mass-radius relation, mass-luminosity relation and H-R diagram of the NCBs provide that the A type NCBs suffer from more active mass transfer than F types. The components of the NCBs ar still in main-sequence like W UMa type stars and their two components lines parallel to the ZAMS.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.246-250
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• 2006

In general, combustion characteristic of hybrid propulsion was shown with the regression rate depending on only massflow rate of oxidizer But this empirical relation was not represented well effect of the thermo-chemical properties of solid fuel. So, in this study, the combustion characteristics was studied with the mass transfer number(B number) of solid fuel instead of regression rate with various fuel. The PMMA, PP, and PE were used as fuel, and gas oxygen as oxidizer in this experiment. The mass flowrate of gas oxigen was controlled by the several chocked orifices that have different diameter, and the oxidizer supply range was $3.66\sim45.3g/sec$. As result, the empirical relation for mass flux of solid fuel was obtained with mass transfer number, and mass flux of oxidizer as follow; $\dot{m}^{'}_f\;=\;0.0175G^{0.55}B^{0.4}$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.2
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• pp.116-122
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• 2004

A micromachined self-exited piezoelectric cantilever has been fabricated using PZT(52/48) thin film. For the application to biosensor using antigen-antibody interaction, electromechanical properties such as resonant frequency and quality factor of micromachined piezoelectric cantilever were important factors. Electromechanical properties and resonant behaviors of microfabricated cantilever were simulated by FEA (Finite Element Analysis) using Coventorware$^{TM}$2003. And these characterization of microcantilever were measured by using LDV(Laser Doppler Vibrometer) to compare with FEA data. We present the resonant frequency shift of micromachined piezoelectric cantilevers due to combination of mass loading and change of spring constant by gold deposition. Experimental mass sensitivities of microcantilever were characterized by Au deposition on the backside of microcantilever. Mass sensitivities with $100{\times}300$ ${\mu}{\textrm}{m}$ dimension cantilever from simulation and experimental were 5.56 Hz/ng and 16.8 Hz/ng respectively.y.