• Journal of the Optical Society of Korea
• /
• v.15 no.3
• /
• pp.232-236
• /
• 2011

We analyze the linear equalizers used in optically amplified on-off-keyed (OOK) systems to combat chromatic dispersion (CD) and polarization mode dispersion (PMD), and we derive the mathematical minimum mean squared error (MMSE) performance of these equalizers. Currently, the MMSE linear equalizer for optical OOK systems is obtained by simulations using adaptive approaches such as least mean squared (LMS) or constant modulus algorithm (CMA), but no theoretical studies on the optimal solutions for these equalizers have been performed. We model the optical OOK systems as square-law nonlinear channels and compute the MMSE equalizer coefficients directly from the estimated optical channel, signal power, and optical noise variance. The accuracy of the calculated MMSE equalizer coefficients and MMSE performance has been verified by simulations using adaptive algorithms.

• Journal of Environmental Science International
• /
• v.12 no.10
• /
• pp.1101-1108
• /
• 2003

We studied the relationship between a civil affair occurrence of bad smell and meteorological conditions around Seongseo district for recent 2 years. The results were as follows; (1) The civil affair occurrence days of bad smell were concentrated from May to August. (2) Daily mean temperatures were mostly 20∼28$^{\circ}C$ and daily mean relative humidities were 60∼80%. (3) Wind speeds were mostly less than 2㎧(75%), and wind directions were southerly winds(50%). It was hardly occurred for relatively well-ventilated conditions in cases of wind speeds 2㎧ over. And the Lagrangian particle dispersion model were used to figure out the transport route in a civil affair occurrence days of bad smell. It was found that the south-western winds transported the bad smelling materials from Jungni-dong(the place of source) to the housing complex located along a piedmont district.

• The Bulletin of The Korean Astronomical Society
• /
• v.39 no.1
• /
• pp.36.1-36.1
• /
• 2014

The correlation between mass of Type Ia Supernova (SN Ia) host galaxies and Hubble residual is now well-established. The origin of this relation, however, is yet to be understood. We have used low-resolution spectra of early-type hosts from YONSEI (YOnsei Nearby Supernovae Evolution Investigation) project to measure central velocity dispersion and Lick/IDS absorption indices. By using the Evolutionary Population Synthesis (EPS) models, luminosity-weighted mean age and metallicity of host galaxies were determined from $H{\beta}$ and absorption lines. Here we will discuss the correlation between the velocity dispersion, which indicates the mass of galaxies, and mean age of stellar population in our sample of early-type host galaxies.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.15 no.4 s.40
• /
• pp.431-435
• /
• 1991

The dispersion and Poiar force components of the surface free energy of PET fibers untreated and treated with hydrophilic chemicals, such as nonionic-soil release polymer (SRP), anionic, nonionic and hydrophilic silicone, were determined using harmonic-mean and geometric-mean methods. Contact angles of water and methylene iodide on the fibers were determined from the adhesion tensions using tensiometric method. Fibers treated with hydrophilic chemicals have the increased polar force component and the decreased dispersion force component. The adhesion tensions of triolein for the hydrophilic treated fibers were smaller than that for untreated fiber.

• The Korean Journal of Applied Statistics
• /
• v.6 no.2
• /
• pp.253-263
• /
• 1993

Recent interest in Taguchi's methods have led to developments of joint modelling of the mean and dispersion in generalized linear models. Since a single data transformation cannot produce all the necessary conditions for an analysis, for the analysis of the Taguchi data, the use of the generalized linear models is preferred to a commonly used data transformation method. In this paper, we will illustrate this point and provide GLIM macros to implement the joint modelling of the mean and dispersion in generalized linear models.

• Bulletin of the Korean Mathematical Society
• /
• v.59 no.4
• /
• pp.979-991
• /
• 2022

A special class of exponential dispersion models is the class of Tweedie distributions. This class is very significant in statistical modeling as it includes a number of familiar distributions such as Gaussian, Gamma and compound Poisson. A Tweedie distribution has a power parameter p, a mean m and a dispersion parameter 𝜙. The value of the power parameter lies in identifying the corresponding distribution of the Tweedie family. The basic objective of this research work resides in investigating the existence of the implicit estimator of the power parameter of the Tweedie distribution. A necessary and sufficient condition on the mean parameter m, suggesting that the implicit estimator of the power parameter p exists, was established and we provided some asymptotic properties of this estimator.

• Korean Journal of Agricultural Science
• /
• v.41 no.4
• /
• pp.315-319
• /
• 2014

Mean densities of two-spotted spider mite (TSM), Tetranichus urticae Koch adults from January to April in 2014 to investigate the occurrence and dispersion pattern of T. urticae on purpose of developing a monitoring method in the strawberry PVC house. Difference of density of T. urticae adult on middle and both side of leaf wasn't significantly. Density of T. urticae in investigation at different furrows and investigating points was the highest at the right and left sides of a furrow in strawberry PVC house. In results of comparing the dispersion incides of Taylor's power law (TPL) with Iwao's patchiness regression (IPR), TPL described better mean-relationship for the dispersion indieces compared to IPR. Slopes and intercepts of TPL from leaf samples did not differ among surveyed regions. Also, Distribution of T. urticae in a strawberry PVC house was the gravitation of the distribution because b and ${\beta}$ values of TPL and IPR was bigger than 1.

• Earthquakes and Structures
• /
• v.14 no.4
• /
• pp.313-322
• /
• 2018

The present study is dedicated to investigate the SH body-as well as Love-waves propagation effects in porous media with uncertain porosity and permeability. A unified formulation of the governing equations for one-dimensional (1-D) wave propagation in anisotropic porous layered media is presented deterministically. The uncertainties around the above two cited parameters are taken into account by random fields with the help of Monte Carlo Simulations (MCS). Random samples of the porosity and the permeability are generated according to the normal and lognormal distribution functions, respectively, with a mean value and a coefficient of variation for each one of the two parameters. After performing several thousands of samples, the mathematical expectation (mean) of the solution of the wave propagation equations in terms of amplification functions for SH waves and in terms of dispersion equation for Love-waves are obtained. The limits of the Love wave velocity in a porous soil layer overlaying a homogeneous half-space are obtained where it is found that random variations of porosity change the zeros of the wave equation. Also, the increase of uncertainties in the porosity (high coefficient of variation) decreases the mean amplification function amplitudes and shifts the fundamental frequencies. However, no effects are observed on both Love wave dispersion and amplification function for random variations of permeability. Lastly, the present approach is applied to a case study in the Adapazari town basin so that to estimate ground motion accelerations lacked in the fast-growing during the main shock of the damaging 1999 Kocaeli earthquake.

• Journal of the Korean Society of Groundwater Environment
• /
• v.2 no.2
• /
• pp.49-57
• /
• 1995

Areas of Chungyang in Chungcheongnamdo, Cheju island and Georgia in U.S.A. were selected to calculate their groundwater ages and dispersion parameters using tritium. Piston flow model, Completely mixing model and Dispersion binomial model which calculate men residence times, and Dispersion normal model and Dispersion model(C$\_$FF) which calculate mean residence times and dispersion parameters simultaneously were applied. Since the input data, tritium concentrations of rainwaters, lack in part, tritium input function was prepared using the correlation of tritium concentrations of rainwaters of Pohang, Korea and Ottawa, Canada. Similar results of PFM and DBM reflect the intrinsical similarity of two models, assumption of low dispersion. The ages of sites of showing relatively higher tritium concentrations than other sites in the sam, region were not calculated by CMM. Since the calculations of DNM and DM(C$\_$FF/) provide the combination of wide ranges of parameters and groundwater ages, the ranges of dispersion parameters were narrowed down under the assumption that ages calculated by PFM and DBM are correct. Since large variation of tritium concentrations of outflows in a same region may reflect the different characteristics of each groundwater flow regime, using only one specific model on a whole region is not recommended.

• Journal of Environmental Science International
• /
• v.3 no.3
• /
• pp.241-252
• /
• 1994

Meteorological parameters In the atmospheric boundary layer and the vertical and horizontal dispersion parameters were determined by analyzing the data obtained by the special upper-air observations of one clear day for each season from October 1991 to August 1992. The concentration of the aklospheric pollutants over Taegu was analyzed by using the application of the Gaussian diffusion model. In the diurnal variation of diffusion of atmospheric pollutants, vertical diffusion due to turbulence is active in daytime while horizontal diffusion due to wind is active in nighttime. The mean concentration of pollutants in the side of downwind is higher during the daytime than the nighttime. Thus, the height of the mixed-layer at the nighttime considered as the most important parameter of the mean concentration of pollutants. In the seasonal variation of diffusion of atmospheric pollutants, vertical diffusion due to strong solar radiation is active in summer case day, and horizontal diffusion due to strong wind is active in winter case day. In winter case day, the mean concentration of pollutants in the side of downwind is maximum in the daytime. However, in summer case day, that is maximum in the nighttime.