• Proceedings of the Korean Statistical Society Conference
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• 2002.05a
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• pp.1-5
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• 2002

We consider the problem of optimal bandwidth choice for nonparametric classification, based on kernel density estimators, where the problem of interest is distinguishing between two univariate distributions. When the densities intersect at a single point, optimal bandwidth choice depends on curvatures of the densities at that point. The problem of empirical bandwidth selection and classifying data in the tails of a distribution are also addressed.

• Journal of Korean Society of Transportation
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• v.28 no.3
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• pp.157-167
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• 2010

Density is the most important congestion indicator among the three fundamental flow variables, flow, speed and density. Measuring density in the field has two different ways, direct and indirect. Taking photos with wide views is one of direct ways, which is not widely used because of its cost and lacking of proper positions. Another direct density measuring method using two point detectors has been introduced with the concept of instantaneous density, average density and measurement interval. The relationship between accuracy and measurement interval has been investigated using the SIMULATION data produced by Paramics Application Programming Interface function. We analyze the affect of segment density accuracy by sensing gap each road condition such as sensing segment length, lane and LOS after gathering data by Paramics Application Programming Interface.

• Journal of the Korean Statistical Society
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• v.27 no.4
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• pp.385-396
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• 1998

A computing method of fractional Bayes factor (FBF) for a point null hypothesis is explained. We propose alternative form of FBF that is the product of density ratio and a quantity using the generalized Savage-Dickey density ratio method. When it is difficult to compute the alternative form of FBF analytically, each term of the proposed form can be estimated by MCMC method. Finally, two examples are given.

• Carbon letters
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• v.2 no.1
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• pp.72-75
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• 2001

The performance of Li-ion system based on $LiCoO_2$ and Graphite is well optimized for the 3C applications. The charge-discharge mode, the manufacturing process, the cell performance and the thermal reactions affecting safety has been explained in the engineering point of view. The energy density of the current LIB system is in the range of 300~400 Wh/l. In order to achieve the energy density higher than 500 Wh/l, the active materials should be modified or changed. Adopting new high capacity anode materials would be effective to improve energy density.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.5
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• pp.550-557
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• 1998

The saturated vapor density correlation proposed here relates logarithmic density to the inverse of temperature. Its performance is examined correlating the date listed in the ASHTAE tables for 40 refrigerants. The correlation equation is valid over the entire range where data point exist and gives better results than a conventional equation with the same number of adjustable coefficients. Number of terms in the equation is a variable so that great flexibility can be given to the representation of data.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.26 no.2
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• pp.108-120
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• 2022

We considered qualitative behaviour of the generalization of Einstein's model of Brownian motion when the key parameter of the time interval of free jump degenerates. Fluids will be characterised by number of particles per unit volume (density of fluid) at point of observation. Degeneration of the phenomenon manifests in two scenarios: a) flow of the fluid, which is highly dispersing like a non-dense gas and b) flow of fluid far away from the source of flow, when the velocity of the flow is incomparably smaller than the gradient of the density. First, we will show that both types of flows can be modeled using the Einstein paradigm. We will investigate the question: What features will particle flow exhibit if the time interval of the free jump is inverse proportional to the density and its gradient ? We will show that in this scenario, the flow exhibits localization property, namely: if at some moment of time t₀ in the region, the gradient of the density or density itself is equal to zero, then for some T during time interval [t₀, t₀ + T] there is no flow in the region. This directly links to Barenblatt's finite speed of propagation property for the degenerate equation. The method of the proof is very different from Barenblatt's method and based on the application of Ladyzhenskaya - De Giorgi iterative scheme and Vespri - Tedeev technique. From PDE point of view it assumed that solution exists in appropriate Sobolev type of space.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.3
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• pp.57-69
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• 2011

This study examined the relationship between Phragmites australis' growth and sediment properties at mud tidal flat of Donggum-ri, Gilsang-myeon, Gangwha-gun, Incheon city. Field survey was carried out from May, 2010 to October, 2010. Water content, soil texture, electric conductivity and water table depth for sediment, density, height, dry weight and flowering for P. australis were examined at several plots from the starting point (the coastal embankment) to the end point of the two populations. The result was as follows. Firstly, the water table increased along distance from the embankment at one line (N-line) but was similar at the other line (S-line) in a P. asustralis population. Water tables were higher out of than within a P. australis population at two populations. Secondary, in N-line, the height and dry weight of P. australis decreased along the distance from embankment but, in S-line, those were similar in its population. P. australis' growth was dependent on electric conductivity at lower layer (water table level) rather than upper one (the surface). Thirdly, density of P. australis changed during growing season and was similar in a population, except for the end point of patch. In summary, the growth and distribution of P. australis were dependent on salt content of tidal flat's sediment (water table level) and this was affected by fresh water of the inland.

• Electrical & Electronic Materials
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• v.8 no.5
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• pp.640-647
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• 1995

In this study, the BaTiO$\sub$3/ capacitor add to MnO$\sub$2/ like depressor and shifter were investigated for temperature or voltage compensation by structural and electrical analysis. The relative density of BCTM, generating poly crystall and formation of lattice defect, has a 90[%] over as the CaTiO$\sub$3/ come out to control grain size. The current density of BCTM2 increased non-ohmic in high-electric field but that BCTM3 and BCTM4 had a few changing. The BCTM3 and BCTM4 unformated grain boundary shown temperature compensation properties, so that the dielectric constant was low value. The curie point was near 140[.deg. C] in BCTM1 and BCTM4, but BCTM3 and BCTM4 not shown the curie point. It is found that the charging energy of BCTM4 was changed 6[%] according to rising temperature from room temperature to 417[K]. The formation of BaMnO$\sub$3/ was low dielectric constant to change frequency and temperature.

• Journal of the Korean Society of Combustion
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• v.4 no.2
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• pp.1-10
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• 1999

Pulverized coal is widely used as the source of electrical power generation and industrial processes. Numerical analysis on the transient ignition process of the cloud of pulverized coal particles in various cases is carried out. Particle radius, initial particle temperature, number density are chosen as major parameters that influence the characteristics of ignition and combustion. The result can be summarized as follow. The ignition occurs at the position that is closed to the surface of the cloud. Maximum temperature and velocity appear at ignition point, and the concentrations of gaseous fuel and oxidizer decrease rapidly near the ignition point. The chemical reaction takes place in wider zone as number density and particle radius decrease. The ignition delay is shortest when particle radius is about $50\;{\mu}m$, and tends to be shorter as number density and initial ambient temperature increase.

• Journal of Korean Society of Transportation
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• v.29 no.3
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• pp.83-91
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• 2011

This paper discusses models for estimating dynamic travel times based on probability theory. The dynamic travel time models proposed in the paper are formulated assuming that the travel time of a vehicle depends on the distribution of the traffic stream condition with respect to the location along a road when the subject vehicle enters the starting point of a travel distance or with respect to the time at the starting point of a travel distance. The models also assume that the dynamic traffic flow can be represented as an exponential distribution function among other types of probability density functions.