• Journal of Korean Society for Atmospheric Environment
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• v.19 no.1
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• pp.45-56
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• 2003

In this study the distribution patterns of the metallic components were analyzed both before and after the Asian Dust (AD) events at 2001 by comparing the chemical composition of metallic components in terms of various statistical methods. According to the AD/NAD concentration ratio of metallic components, the main components of crustal soils were exhibiting the values above 1.0; but opposite results were seen dominantly for hazardous metallic components. Examination of fine-to-coarse (F/C) ratios of metallic components showed higher values for major anthropogenic components including Pb (5.83). Ni (2.61), etc. Comparison of our measurement data with those obtained within and across the Korean peninsula indicated that the metallic distribution patterns of the study area can be distinguished from previous studies. The results of our analysis, when investigated in relation with air mass movement patterns. indicated evidence of the direct influence of AD events and anthropogenic processes.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.3
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• pp.105-109
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• 2011

Drift Velocity of Electrons in pure $CF_4$, $CH_4$ and mixtures of $CF_4$ and Ar. Have been analyzed over a range of the reduced electric field strength between 0.1 and 350[Td] by the two-term approximation of the Boltzmann equation (BEq.) method and the Monte Carlo simulation (MCS). The results of the Boltzmann equation and the Monte Carlo simulation have been compared with the data presented by several workers. The deduced transport coefficients for electrons agree reasonably well with the experimental and simulation data obtained by Nakamura and Hayashi. The energy distribution function of electrons in $CF_4$-Ar mixtures shows the Maxwellian distribution for energy. That is, f(${\varepsilon}$) has the symmetrical shape whose axis of symmetry is a most probably energy. The measured results and the calculated results have been compared each other.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.260-264
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• 1996

In this study, the dieiectric breakdown of epoxy composites used for transformers was experimented and then its data were simulated by Weibull distribution probability . As a result. first of all, speaking of dielectric breakdown properties, the more hardener increased the stronger breakdown strength at low temperature, and the breakdown strength of specimens because it is believed that the adding filler farms interface and charge is accumulated in it, therefore the molecular motility is raised, the electric field is concentrated, and the acceleration of electron and the growth of electron avalanche are early accomplished. In the case of filled specimens with treating silane, the breakdown strength become much higher since the suggests that silane coupling agent improves interfacial combination and relays electric field concentration. Finally, from the analysis 7f weibull distribution. it was confirmed that as the allowed breakdown probability was given by 0.11[%].

• Journal of Life Science
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• v.19 no.6
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• pp.693-697
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• 2009

The purpose of the present investigation was to investigate diversity patterns in Mt. Neungdong forested landscape. It was conducted on twelve sloping plots $(100{\times}100 m)$ in the east and west sides of Mt. Neungdong. A total of 2,157 specimins were identified as trees with a diameter at breast height (DBH) ${\geq}$10 em. There were a total of 135 species of 35 families present in both regions of Mt. Neungdong. Least significant differences (LSD) by post hoc analysis revealed that region A had significantly greater densities than region B. Shannon-Wiener functions differed significantly between forests (F=4.12, < 0.05), with region B forest having a significantly higher value (2.118) than region A (1.882). Pinus thunbergii and Quercus aliena were dominant on most plots of both regions, however, the P. densiflora forest of region A was distributed better in the middle plots exposures compared to the opposite ones. Q. aliena, Q. mongolica, and Carpinus laxiflora largely occupied the middle and lower exposures of region B. The spatial distribution in Neungdong's forest was very heterogeneous and reflected by most species as having micro-climate and patchy distributions.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.6
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• pp.592-596
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• 2014

We shall consider fuzzy hypotheses test for signed-rank Wilcoxon fuzzy test by fuzzy difference on rate of internal division. Fundamental to these discussion are fuzzy number data and Wilcoxon signed-rank fuzzy test of a fuzzy hypothesis $H_{f0}$ which is based upon a fuzzy statistics whose distribution does not depend upon the specified distribution or any parameters.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.285-290
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• 2006

To access the volume of sediments deposited after construction of the Soyang Dan and to understand their distribution in the Soyang lake, acoustic profiling using a 10-20 kHz system was conducted along profiles of 227 km length. Profile intervals are approximately 50 and 500 m for longitudinal and cross lines, respectively. The data were gain-controlled and then migrated using the f-k algorithm. After digitization of boundaries of the sediments, the acoustic interpretation was verified through correlating with 38 core samples. Thickness of the sediments averages 0.25 m and reaches to 8.25 m at maximum. Estimated total volume of the sediments based on anisotropic models in geostatistical methods is approximately $5.9{\times}10^6\;m^3$, which is more than twice greater than the earlier estimation based on an isotropic model.

• Journal of applied mathematics & informatics
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• v.25 no.1_2
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• pp.67-83
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• 2007

The characteristics of steady two-dimensional laminar boundary layer flow of a viscous and incompressible fluid past a moving wedge with suction or injection are theoretically investigated. The transformed boundary layer equations are solved numerically using an implicit finite-difference scheme known as the Keller-box method. The effects of Falkner-Skan power-law parameter (m), suction/injection parameter ($f_0$) and the ratio of free stream velocity to boundary velocity parameter (${\lambda}$) are discussed in detail. The numerical results for velocity distribution and skin friction coefficient are given for several values of these parameters. Comparisons with the existing results obtained by other researchers under certain conditions are made. The critical values of $f_0$, m and ${\lambda}$ are obtained numerically and their significance on the skin friction and velocity profiles is discussed. The numerical evidence would seem to indicate the onset of reverse flow as it has been found by Riley and Weidman in 1989 for the Falkner-Skan equation for flow past an impermeable stretching boundary.

• Child Health Nursing Research
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• v.29 no.4
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• pp.280-289
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• 2023

Purpose: This study investigated weight status in survivors of childhood acute lymphocytic leukemia (ALL) and identified related factors. Methods: A retrospective review of the electronic medical records of survivors of childhood ALL (n=230) was conducted. We analyzed the survivors' characteristics, including sex, age, weight status at diagnosis, central nervous system involvement, risk classification, length of treatment, radiation therapy, and hematopoietic stem cell transplantation. Analysis of variance and the chi-squared test were applied to investigate influencing factors. Results: The weight status distribution was as follows: 23 individuals (10.0%) were classified as underweight, 151 individuals (65.7%) were healthy weight, and 56 individuals (24.3%) were overweight/obese. Age at diagnosis (F=10.03, p<.001), weight status at diagnosis (x²=43.41, p<.001), and risk classification (F=10.98, p=0.027) showed significant differences among the weight status groups. Survivors who were older at diagnosis and those in the very high-risk category had a higher likelihood of experiencing underweight status during their survivorship, while survivors who were overweight/obese at diagnosis were more likely to remain overweight/obese at the time of survival. Conclusion: Considering the potential health implications related to an unhealthy weight status in survivors of ALL, it is imperative to undertake early identification and implement interventions for at-risk individuals.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.11
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• pp.902-909
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• 1991

A reproducible selective dry etch process of GaAs/AlGaAs Heterostructures for High Electron Mobility Transistor(HEMT) Device fabrication is developed. Using RIE mode with $CCl_{2}F_{2}$ as the basic process gas, the observed etch selectivity of GaAs layer with respect to GaAs/$Al_{0.3}Ga_{0.7}$As is about 610:1. Severe polymer deposition problem, parialy generated from the use of $CCl_{2}F_{2}$ gas only, has been significantly reduced by adding a small amount of He gas or by $O_{2}$ plasma ashing after etch process. In order to obtain an optimized etch process for HEMT device fabrication, we com pared the properties of the wet etched Schottky contact with those of the dry etched one, and set dry etch condition to approach the characteristics of Schottky diode on wet etched surface. By applying the optimized etch process, the fabricated HEMT devices have the maximum transconductance $g_{mext}$ of 224 mS/mm, and have relatively uniform distribution across the 2inch wafer in the value of 200$\pm$20mS/mm.

• Geomechanics and Engineering
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• v.21 no.4
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• pp.349-356
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• 2020

Rock brittleness, which is closely related to the failure modes, plays a significant role in the design and construction of many rock engineering applications. However, the brittle-ductile failure transition is mostly ignored by the current statistical damage constitutive model, which may misestimate the failure strength and failure behaviours of intact rock. In this study, a new statistical damage model considering rock brittleness is proposed for brittle to ductile behaviour of rocks using brittleness index (BI). Firstly, the statistical constitutive damage model is reviewed and a new statistical damage model considering failure mode transition is developed by introducing rock brittleness parameter-BI. Then the corresponding damage distribution parameters, shape parameter m and scale parameter F₀, are expressed in terms of BI. The shape parameter m has a positive relationship with BI while the scale parameter F₀ depends on both BI and ε_e. Finally, the robustness and correctness of the proposed damage model is validated using a set of experimental data with various confining pressure.