arXiv subjects

Chang-Yong Lee

Publications and source records attributed to Chang-Yong Lee.

6 recordsLinked to original sources

arXiv2016

A model for the clustered distribution of SNPs in the human genome

Motivated by a non-random but clustered distribution of SNPs, we introduce a phenomenological model to account for the clustering properties of SNPs in the human genome. The phenomenological model is based on a preferential mutation to the closer proximity of existing SNPs. With the Hapmap SNP data, we empirically demonstrate that the preferential model is better for illustrating the clustered distribution of SNPs than the random model. Moreover, the model is applicable not only to autosomes but also to the X chromosome, although the X chromosome has different characteristics from autosomes. The analysis of the estimated parameters in the model can explain the pronounced population structure and the low genetic diversity of the X chromosome. In addition, correlation between the parameters reveals the population-wise difference of the mutation probability. These results support the mutational non-independence hypothesis against random mutation.

q-bio.GN↗

arXiv2014

An efficient method for solving a correlated multi-item inventory system

We propose an efficient method of finding an optimal solution for a multi-item continuous review inventory model in which a bivariate Gaussian probability distribution represents a correlation between the demands of different items. By utilizing appropriate normalizations of the demands, we show that the normalized demands are uncorrelated. Furthermore, the set of equations coupled with different items can be decoupled in such a way that the order quantity and reorder point for each item can be evaluated independently from those of the other. As a result, in contrast to conventional methods, the solution procedure for the proposed method can be much simpler and more accurate without any approximation. To demonstrate the advantage of the proposed method, we present a solution scheme for a multi-item continuous review inventory model in which the demand of optional components depend on that of a "vanilla box", representing the customer's stochastic demand, under stochastic payment and budget constraints. We also perform a sensitivity analysis to investigate the dependence of order quantities and reorder points on the correlation coefficient.

physics.comp-ph↗

arXiv2006

Correlations among centrality measures in complex networks

In this paper, we empirically investigate correlations among four centrality measures, originated from the social science, of various complex networks. For each network, we compute the centrality measures, from which the partial correlation as well as the correlation coefficient among measures is estimated. We uncover that the degree and the betweenness centrality are highly correlated; furthermore, the betweenness follows a power-law distribution irrespective of the type of networks. This characteristic is further examined in terms of the conditional probability distribution of the betweenness, given the degree. The conditional distribution also exhibits a power-law behavior independent of the degree which explains partially, if not whole, the origin of the power-law distribution of the betweenness. A similar analysis on the random network reveals that these characteristics are not found in the random network.

physics.soc-ph↗

arXiv2006

Mass Fractal Dimension of the Ribosome and Implication of its Dynamic Characteristics

Self-similar properties of the ribosome in terms of the mass fractal dimension are investigated. We find that both the 30S subunit and the 16S rRNA have fractal dimensions of 2.58 and 2.82, respectively; while the 50S subunit as well as the 23S rRNA has the mass fractal dimension close to 3, implying a compact three dimensional macromolecule. This finding supports the dynamic and active role of the 30S subunit in the protein synthesis, in contrast to the pass role of the 50S subunit.

q-bio.BM↗

arXiv2006

Statistical Self-Similar Properties of Complex Networks

It has been shown that many complex networks shared distinctive features, which differ in many ways from the random and the regular networks. Although these features capture important characteristics of complex networks, their applicability depends on the type of networks. To unravel ubiquitous characteristics that complex networks may have in common, we adopt the clustering coefficient as the probability measure, and present a systematic analysis of various types of complex networks from the perspective of statistical self-similarity. We find that the probability distribution of the clustering coefficient is best characterized by the multifractal; moreover, the support of the measure had a fractal dimension. These two features enable us to describe complex networks in a unified way; at the same time, offer unforeseen possibilities to comprehend complex networks.

physics.soc-ph↗

arXiv1995

Projectile $Δ$ Excitations in $p(p,n)Nπ$ Reactions

It has recently been proven from measurements of the spin-transfer coefficients $D_{xx}$ and $D_{zz}$ that there is a small but non-vanishing $ΔS=0$ component $σ_{0}$, in the inclusive $p(p,n)Nπ\,$ reaction cross section $σ\,$. It is shown that the dominant part of the measured $σ_{0}$ can be explained in terms of the projectile $Δ$ excitation mechanism. An estimate is further made of contributions to $σ_{0}$ from s-wave rescattering process. It is found that s-wave rescattering contribution is much smaller than the contribution coming from projectile $Δ$ excitation mechanism. The addition of s-wave rescattering contribution to the dominant part, however, improves the fit to the data.

nucl-th↗