• 한국지구물리탐사학회:학술대회논문집
• /
• 2003.11a
• /
• pp.340-343
• /
• 2003

This study presents a practical procedure for the Bayesian inversion of geophysical data by Markov chain Monte Carlo (MCMC) sampling and geostatistics. We have applied geostatistical techniques for the acquisition of prior model information, and then the MCMC method was adopted to infer the characteristics of the marginal distributions of model parameters. For the Bayesian inversion of dipole-dipole array resistivity data, we have used the indicator kriging and simulation techniques to generate cumulative density functions from Schlumberger array resistivity data and well logging data, and obtained prior information by cokriging and simulations from covariogram models. The indicator approach makes it possible to incorporate non-parametric information into the probabilistic density function. We have also adopted the MCMC approach, based on Gibbs sampling, to examine the characteristics of a posteriori probability density function and the marginal distribution of each parameter. This approach provides an effective way to treat Bayesian inversion of geophysical data and reduce the non-uniqueness by incorporating various prior information.

• Journal of the Korean Statistical Society
• /
• v.29 no.3
• /
• pp.307-313
• /
• 2000

Suppose we have a set of data X1, ···, Xn and employ kernel density estimator to estimate the marginal density of X. in this article bandwith selection problem for kernel density estimator is examined closely. In particular the Kullback-Leibler method (a bandwith selection methods based on average square error (ASE)) is considered.

• Journal of Astronomy and Space Sciences
• /
• v.23 no.3
• /
• pp.237-244
• /
• 2006

We produced the electron density distribution in the ionosphere over South Korea using the data from nine permanent GPS (Global Positioning System) stations which have been operated by KASI (Korea Astronomy and Space Science Institute). The dual-frequency GPS receiver data was used to precisely estimate the electron density in the ionosphere and we obtained the precise electron density profile based on two-dimensional TEC (Total Electron Contents). We applied ART (Algebraic Reconstruction Technique), which is one of the most commonly used algorithms to develop the tomography model. This paper presented the electron density distribution over South Korea with time. We compared with the electron density profiles derived from the GPS tomography reconstruction, Ionosonde measurement data obtained by observations, and the IRI-2001 values. As a result, the electron density profile by GPS reconstruction was in excellent agreement with the electron density profile obtained by Ionosonde measurement data.

• Science of Emotion and Sensibility
• /
• v.13 no.1
• /
• pp.279-284
• /
• 2010

This paper surveys basic research for data base system of the fabric structural design. For this purpose, the weave density coefficients of the worsted and cotton fabrics are analysed and discussed with cover factors suggested by Prof. Walz and Picanol company. And the relationship between weave density coefficients and cover factors of the worsted and cotton woven fabrics was analysed and discussed with weave pattern and yarn count. Finally, the process shrinkages of dyeing and finishing processes according to the weave density coefficients of the worsted and cotton fabrics were analysed and discussed as a preliminary study for the data base system of the fabric structural design. As a result, the density coefficients, K values of the worsted and cotton fabrics were ranged from 600 to 1000, and the weave density coefficients of those fabrics are ranged from 0.4 to 0.8 and from 0.2 to 1.0, respectively. The finishing shrinkages for the worsted fabrics are ranged from 2% to 10%, and for cotton fabrics, it was from 2% to 20%. The weave density coefficients of the worsted and cotton fabrics could be distributed according to the looms, weave pattern and weaving and finishing shrinkages as a concept of the data base for the fabric structural design.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.17 no.2
• /
• pp.196-201
• /
• 2007

The Fuzzy E-means (FCM) algorithm is a widely used clustering method that incorporates probabilitic memberships. Due to these memberships, it can be sensitive to noise data. In this paper, we propose a new fuzzy C-means clustering algorithm by incorporating the Parzen Window method to include density information of the data. Several experimental results show that our proposed density-based FCM algorithm outperforms conventional FCM especially for data with noise and it is not sensitive to initial cluster centers.

• Journal of the Korean Data and Information Science Society
• /
• v.22 no.1
• /
• pp.107-113
• /
• 2011

We present methods for studying the log-density ratio, which allow us to select which predictors are needed, and how they should be included in the logistic regression model. Under multivariate normal distributional assumptions, we investigate the form of the log-density ratio as a function of many predictors. The linear, quadratic and crossproduct terms are required in general. If two covariance matrices are equal, then the crossproduct and quadratic terms are not needed. If the variables are uncorrelated, we do not need the crossproduct terms, but we still need the linear and quadratic terms.

• Communications for Statistical Applications and Methods
• /
• v.2 no.2
• /
• pp.231-242
• /
• 1995

In this paper we consider kernel type estimator of the spectral density at a point in the analysis of stationary time series data. The kernel entails choice of smoothing parameter called bandwidth. A data-based bandwidth choice is proposed, and it is obtained by solving an equation similar to Sheather(1986) which relates to the probability density estimation. A Monte Carlo study is done. It reveals that the spectral density estimates using the data-based bandwidths show comparatively good performance.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2007.06a
• /
• pp.101-106
• /
• 2007

A time-lapse microgravity survey on a newly widen road at Muan, where limestone cavities are developed, for monitoring the change of the subsurface density distribution before and after grouting. Microgravity monitoring is identified as a quick, easy and cost effective. But, it requires strict data acquisition and quality control due to the differences of conditions at measurements. The survey was carried out two times, that is, October 2005 and September 2006. The data were adjusted for reducing the effects due to the different condition of each survey. The processed data acquired in 2005 and 2006 were inverted into the subsurface density distributions. They show the change and development of density structure during the lapsed time, which implies the effects of grouting.

• Applied Microscopy
• /
• v.50
• /
• pp.6.1-6.6
• /
• 2020

The cerebellum is a region of the brain that plays an important role in motor control. It is classified phylogenetically into archicerebellum, paleocerebellum and neocerebellum. The Purkinje cells are lined in a row called Purkinje cell layer and it has a unique dendritic branches with many spines. The previous study reported that there is a difference of synapse density according to the lobules based on large two-dimensional data. However, recent study with high voltage electron microscopy showed there was no differences in dendritic spine density of the Purkinje cell according to its phylogenetic lobule. We analyzed Purkinje cell density in the II, VI and X lobules by stereological modules and synaptic density was estimated by double disector based on Purkinje cell density in the molecular layer of each lobule. The results showed that there was significant difference in the Purkinje cell density and synapse number according to their phylogenetic lobules. The number of Purkinje cell in a given volume was larger in the archicerebellum, but synapse density was higher in the neocerebellum. These data suggest that cellular and synaptic organization of the Purkinje cell is different according to their phylogenetic background.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.7 no.2
• /
• pp.117-120
• /
• 2002

The effect of cell density on cell growth was investigated in a suspension batch culture of hybridoma cells. The specific growth rate was found to increase with increasing initial cell density and then to decrease with further increases in initial cell density. In order to quantitatively describe the dependence of specific growth rate on cell density, a kinetic model is proposed, which satisfactorily represents the experimental data.