• Journal of the Korean Data and Information Science Society
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• v.10 no.1
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• pp.243-250
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• 1999

We consider $Y=X{\lambda}Z,\;{\lambda}>0$, where X and Z are independent random variables, and Y is the length biased distribution or the equilibrium distribution of X. The purpose of this paper is to consider the distribution of X or Y when the distribution of Z is given and the distribution of Z when the distribution of X or Y is given, In particular, we obtain that the necessary and sufficient conditions for X to be $X^{2}({\upsilon})\;is\;Z{\sim}X^{2}(2)\;and\;for\;Z\;to\;be\;X^{2}(1)\;is\;X{\sim}IG({\mu},\;{\mu}^{2}/{\lambda})$, where $IG({\mu},\;{\mu}^{2}/{\lambda})$ is two-parameter inverse Gaussian distribution. Also we show that X is smaller than Y in the reverse Laplace transform ratio order if and only if $X_{e}$ is smaller than $Y_{e}$ in the Laplace transform ratio order. Finally, we can get the results that if X is smaller than Y in the Laplace transform ratio order, then $Y_{L}$ is smaller than $X_{L}$ in the Laplace transform order, and that if X is smaller than Y in the reverse Laplace transform ratio order, then $_{\mu}X_{L}$ is smaller than $_{\nu}Y_{L}$ in the Laplace transform order.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.74.2-74.2
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• 2012

Metallicity is an important tracer of star formation in galaxy evolution. Based on the flux ratios of broad emission lines, AGN metallicity has shown a correlation with AGN luminosity. However, it is not clear what physical parameter drives the observed correlation. Using a sample 69 Palomar-Green QSOs at low-z (z<0.5), we determine BLR gas metallicity from emission line flux ratios, i.e., N V1240/C IV1549, (Si IV1398+O IV1402)/C IV1549 and N V1240/He II1640 based on the UV spectra from the HST and IUE archives. We compare BLR gas metallicity with various AGN properties, i.e., black hole mass, AGN luminosity and Eddington ratio, in order to investigate physical connection between metal enrichment and AGN activity. In contrast to high-z QSOs, which show the correlation between metallicity and black hole mass, we find that the metallicity of low-z QSOs correlates with Eddington ratio, but not with black hole mass, suggesting that metallicity enrichment mechanism is different between low-z and high-z.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.71.1-71.1
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• 2012

We have identified local analogs of strong $H{\alpha}$ Emitters (HAEs) that dominate the z~4 Lyman-break galaxy population using the Sloan Digital Sky Survey (SDSS). At z<0.4, only 0.04% of galaxies are classified as HAEs with $H{\alpha}$ equivalent width larger than $500{\AA}$, comparable to that of z~4 HAEs. The $H{\alpha}$-to-UV luminosity ratio of local HAEs is consistent with that of z~4 HAEs, indicating relatively large specific star formation rate in these galaxies compared to traditionally studied UV-selected Lyman break analogs. Local HAEs are young, less evolved galaxies with low metallicity. It is still difficult to constrain whether the star formation in local HAEs is powered by minor mergers or by cosmological cold gas accretion. However, the stacked optical spectrum of local HAEs shows several strong ionization lines, for example HeII 4686 emission line, which are shown in Wolf-Rayet galaxies. Thus it is highly likely that local HAEs are galaxies with an elevated ionization parameter, either due to a high electron density or large escape fraction of hydrogen ionizing photons.

• Archives of Pharmacal Research
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• v.10 no.2
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• pp.94-99
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• 1987

By using the former equation (8), we modified the equation which can show the dissimilar osmotic behavior of liposome with composition change. The slope of the new equation was presented as the ratio of osmotically active volume (V$_{act}$= ) to the total volume (V$_{totel}$= $_{acl}$+ V$_{dead}$ ; V$_{dead}$ is osmotically inactive volume) of loposomes, we defined is as a Z-value, which can elucidate the dissimilarity of the osmotic activity of multilamellar liposomes with the change of phospholipid composition and the differences of physicochemical properties of liposomes. Z-value was applied for studying the physico-chemical properties of liposomal membrane. The factor that affects on the Z-value was not the lipid concentration of liposome stock dispersion but the lipid composition of liposomal membrane. As the content of dicetylphosphate, the negative charged phospholipid, was increased, the osmotic activity, represented by Z-value, of multilamellar liposome was decreased. Using the hypertonic conditions (shrinking region), Z-value steadily increased and reached a maximum at 10 mole percent cholesterol with increasing the cholesterol content.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.449-454
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• 1994

This paper describes new PID control methods based on the fuzzy logic. PID gains are retuned after evaluating control performances of transient responses in terms of performance features. The retuning procedure is based on fuzzy rules and reasoning accumulated from the knowledge of experts on PID gain scheduling. For the case that the retuned PID gains result in worse CLDR (characteristics of load disturbance rejection) than the initial gains, an on-line tuning scheme of the set-point weighting parameter is, proposed. This is based on the fact that the set-point weighting method efficiently reduce either overshoot or undershoot without any degradation of CLDR. The set-point weighting parameter is adjusted at each sampling instant by the fuzzy rules and reasoning. As a result, better control performances were achived in comparison with die controllers tuned by the Z-N (Ziegler-Nichols) parameter tuning formula or by the fixed set-point weighting parameter.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.66-71
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• 2003

Profiles of naturally fractured surfaces of three sedimentary rock samples were plotted from the measured data using a mechanical profilometer. Fractal dimension of these profiles were computed and statistical F-test indicates that fractal dimension (FD) values can be used as a parameter for distinguishing the rock types. The comparison between FD values and a commonly used profile-roughness parameter called the Mayer's $Z_2$ parameter shows the superiority of the FD values as roughness estimator. Two-dimensional fractal roughness parameters of the same naturally fractured rock surfaces were also studied from their scanning electron microscopic (SEM) images at various magnification levels. The most suitable level of magnification of the SEM images for the study of the 2-D fractal roughness parameter was identified. The values of 2-D fractal roughness parameter for three different rocks were also compared using different methods of fractal dimensioning.

• Journal of KSNVE
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• v.8 no.5
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• pp.964-973
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• 1998

In this paper we propose a levitation and imbalance compensation controller design methodology of magnetic bearing system. In order to achieve levitation and elimination of unbalance vibartion in some operation speed we use the discrete-time Q-parameterization control. When rotor speed p = 0 there are no rotor unbalance, with frequency equals to the rotational speed. So in order to make levitatiom we choose the Q-parameterization controller free parameter Q such that the controller has poles on the unit circle at z = 1. However, when rotor speed p $\neq$ 0 there exist sinusoidal disturbance forces, with frequency equals to the rotational speed. So in order to achieve asymptotic rejection of these disturbance forces, the Q-parameterization controller free parameter Q is chosen such that the controller has poles on the unit circle at z = $exp^{ipTs}$ for a certain speed of rotation p ( $T_s$ is the sampling period). First, we introduce the experimental setup employed in this research. Second, we give a mathematical model for the magnetic bearing in difference equation form. Third, we explain the proposed discrete-time Q-parameterization controller design methodology. The controller free parameter Q is assumed to be a proper stable transfer function. Fourth, we show that the controller free parameter which satisfies the design objectives can be obtained by simply solving a set of linear equations rather than solving a complicated optimization problem. Finally, several simulation and experimental results are obtained to evaluate the proposed controller. The results obtained show the effectiveness of the proposed controller in eliminating the unbalance vibrations at the design speed of rotation.

• Proceedings of the Acoustical Society of Korea Conference
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• 1984.12a
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• pp.66-69
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• 1984

This paper is a study on the Endpoint Detection for Korean Speech Recognition. In speech signal process, analysis parameter was classification from Zero Crossing Rate(Z.C.R), Log Energy(L.E), Energy in the predictive error(Ep) and fundamental Korean Speech digits, /영/-/구/ are selected as date for the Recognition of Speech. The main goal of this paper is to develop techniques and system for Speech input ot machine. In order to detect the Endpoint, this paper makes choice of Log Energy(L.E) from various parameters analysis, and the Log Energy is very effective parameter in classifying speech and nonspeech segments. The error rate of 1.43% result from the analysis.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.39.2-39
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• 2002

This paper presents adaptive add-on control algorithms for theconventional mode of operation of MEMS z-axis gyroscopes. This scheme is realized by adding an outer loop to a conventional force-balancing scheme that includes a parameter estimation algorithm. The parameter adaptation algorithm estimates the angular rate, identifies and compensates the quadrature error, and may permit on-line automatic mode tuning. The convergence and resolution analysis show that the proposed adaptive add-on control scheme prevents the angular rate estimate from being contaminated by the quadrature error, while keeping ideal resolution performance of a conventional force-balancing scheme.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1765-1777
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• 2014

This study evaluated PMM (Probability Matching Method) for parameter estimation of the Z - R relation. As a first step, the sensitivity analysis was done to decide the threshold number of data pairs and the data interval for the development of a histogram. As a result, it was found that at least 1,000 number of data pairs are required to apply the PMM for the parameter estimation. This amount of data is similar to that collected for two hours. Also, the number of intervals for the histogram was found to be at least 100. Additionally, it was found that the matching the first-order moment is better than the cumulative probability, and that the data pairs comprising 30 to 100% are better for the PMM application. Finally, above findings were applied to a real rainfall event observed by the Bislsan radar and optimal parameters were estimated. The radar rain rate derived by applying these parameters was found to be well matched to the rain gauge rain rate.