• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.165-177
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• 2019

This paper considers corrosion wastage of two ship hull structure members as a part of investigated fuel oil tanks of 25 aging bulk carriers. Taking into account that many factors which influence corrosion wastage of ship hull structures are of uncertain nature, the related corrosion rate ($c_1$) is considered here as a real-valued continuous distribution, assuming that the corrosion wastage starts after 5, 6 or 7 years. In all considered cases, by using available data and applying three basic statistical tests, it is established that between two-parameter continuous distributions, normal, Weibull and logistic distributions are best fitted distributions for the mentioned corrosion rate ($c_1$). Note that the presented statistical, numerical and graphical results concerning two mentioned ship hull structure members allow to compare and discuss the corresponding probabilistic estimates for the corrosion rate ($c_1$).

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.2
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• pp.234-240
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• 2010

Gas flow uniformity is an important factor to guarantee particle removal performance of electrostatic precipitators (EP), and the gas flow uniformity is evaluated by a fraction of standard deviation to the mean of gas flow distribution (%RMS) or a technical standard, ICAC EP-7, provided by The Institute of Clean Air Companies. In this study, relationship between the ICAC EP-7 and %RMS in evaluation of gas flow uniformity was investigated in terms of flow velocity. The maximum values of %RMS for gas velocity distribution of normal distribution has been obtained, and the maximum values of %RMS with gas velocity distribution satisfying ICAC EP-7 standards were also evaluated. With gas flow distribution obtained from CFD analysis and physical model test of real EP, %RMS values were calculated and it was tested if those gas flow distribution satisfy the criteria specified in ICAC EP-7. The %RMS values satisfying criteria of ICAC have been appeared to have similar values with %RMS values calculated with normal distribution of gas velocities.

• Bulletin of the Korean Mathematical Society
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• v.44 no.2
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• pp.265-270
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• 2007

The modern approach for wavelets imposes a Bayesian prior model on the wavelet coefficients to capture the sparseness of the wavelet expansion. The idea is to build flexible probability models for the marginal posterior densities of the wavelet coefficients. In this note, we derive exact expressions for a popular model for the marginal posterior density.

• Communications of the Korean Mathematical Society
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• v.34 no.2
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• pp.495-506
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• 2019

Motivated by Bloch's principle, we prove a value distribution result for meromorphic functions which is related to Hayman's alternative in certain sense.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.4_5
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• 2009

A new protection coordination algorithm in Multi-Agent based distribution automation system is proposed in this paper. Distribution network protection coordination is acted by normal state distribution operation. But, in more and more complex distribution network structure, it has a big problem that central server processed all measurement data, coordination setting and controls for operation. So, a algorithm to change coordination setting is proposed automatically in terminal devices which Recloser and OCR to include Multi-Agent concepts in distribution network.

• Water Engineering Research
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• v.6 no.2
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• pp.49-61
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• 2005

This paper presents the numerical study to examine characteristics of fluid flow and solute transport in a rough fracture subject to effective normal stresses. The aperture distribution is generated by using the self-affine fractal model. In order to represent a nonlinear relationship between the supported normal stress and the fracture aperture, we combine a simple mechanical model with the local flow model. The solute transport is simulated using the random walk particle following algorithm. Results of numerical simulations show that the flow is significantly affected by the geometry of aperture distribution varying with the effective normal stress level while it is slightly affected by the fractal dimension that determines the degree of the fracture surface roughness. However, solute transport is influenced by the effective normal stress as well as the fracture surface roughness.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.2
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• pp.243-247
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• 2016

Driving Event Data such as the rapid acceleration, the rapid deceleration, the sudden braking, and the sudden departure, and over speeding provide important information to predict or analyze the driving habits and accident risk of a driver. Most of the data that represent the driver's driving habits generally fit to the parametric distribution, whereas extreme parts of the data to estimate the accident risk of a driver may not. This paper presents an empirical distribution that is divided into two regions, one is from the normal distribution, and the other is from the general pareto distribution for the driving habits of a driver.

• Journal of Ocean Engineering and Technology
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• v.34 no.1
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• pp.26-36
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• 2020

An extreme value analysis of metocean data which include wave, wind, and current data is a prerequisite for the operation and survival of offshore structures. The purpose of this study was to provide information about the return wave, wind, and current values for the Barents Sea using extreme value analysis. Hindcast datasets of the Global Reanalysis of Ocean Waves 2012 (GROW2012) for a waves, winds and currents were obtained from the Oceanweather Inc. The Gumbel distribution, 2 and 3 parameters Weibull distributions and log-normal distribution were used for the extreme value analysis. The least square method was used to estimate the parameters for the extreme value distribution. The return values, including the significant wave height, spectral peak wave period, wind speed and current speed at surface, were calculated and it will be utilized to design offshore structures to be operated in the Barents Sea.

• Smart Structures and Systems
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• v.25 no.5
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• pp.593-604
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• 2020

Temperature may have more significant influences on structural responses than operational loads or structural damage. Therefore, a comprehensive understanding of temperature distributions has great significance for proper design and maintenance of bridges. In this study, the temperature distribution of the steel box girder is systematically investigated based on the structural health monitoring system (SHMS) of the Sutong Cable-stayed Bridge. Specifically, the characteristics of the temperature and temperature difference between different measurement points are studied based on field temperature measurements. Accordingly, the probability density distributions of the temperature and temperature difference are calculated statistically, which are further described by the general formulas. The results indicate that: (1) the temperature and temperature difference exhibit distinct seasonal characteristics and strong periodicity, and the temperature and temperature difference among different measurement points are strongly correlated, respectively; (2) the probability density of the temperature difference distribution presents strong non-Gaussian characteristics; (3) the probability density function of temperature can be described by the weighted sum of four Normal distributions. Meanwhile, the temperature difference can be described by the weighted sum of Weibull distribution and Normal distribution.

• Journal of Navigation and Port Research
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• v.34 no.8
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• pp.609-614
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• 2010

This paper describes statistical parameter estimation to calculate collision probabilities between Mokpo Harbor Bridge and passing vessels. At first, we obtained AIS (Automatic Identification System) information from passing vessels, then after, analyzed the lateral distributions of vessel tracks and estimated the mean and the standard deviation for the distance away from bridge center, the passing course and the passing speed. The analysis results of track distribution for the distance away and the passing course are shown as normal type, otherwise the speed distribution shown as two kinds of different normal type. In addition, we testified that the usefulness of estimated parameter values through the relative comparison between the track distributions and it's normal probability distributions.