• Korean Journal of Remote Sensing
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• v.34 no.3
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• pp.481-494
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• 2018

The accurate radiative transfer model simulation is essential for an accurate ozone profile retrieval using optimal estimation from backscattered ultraviolet (BUV) measurement. The input parameters of the radiative transfer model are the main factors that determine the model accuracy. In particular, meteorological parameters such as temperature and surface pressure have a direct effect on simulating radiation spectrum as a component for calculating ozone absorption cross section and Rayleigh scattering. Hence, a sensitivity of UV ozone profile retrievals to these parameters has been investigated using radiative transfer model. The surface pressure shows an average error within 100 hPa in the daily / monthly climatological data based on the numerical weather prediction model, and the calculated ozone retrieval error is less than 0.2 DU for each layer. On the other hand, the temperature shows an error of 1-7K depending on the observation station and altitude for the same daily / monthly climatological data, and the calculated ozone retrieval error is about 4 DU for each layer. These results can help to understand the obtained vertical ozone information from satellite. In addition, they are expected to be used effectively in selecting the meteorological input data and establishing the system design direction in the process of applying the algorithm to satellite operation.

• The Korean Journal of Applied Statistics
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• v.27 no.4
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• pp.645-653
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• 2014

P-value is the probability of observing a current sample and possibly other samples departing equally or more extremely from the null hypothesis toward postulated alternative hypothesis. When p-value is less than a certain level called ${\alpha}$(= 0:05), researchers claim that the alternative hypothesis is supported empirically. Unfortunately, some findings discovered in that way are not reproducible, partly because the p-value itself is a statistic vulnerable to random variation. Boos and Stefanski (2011) suggests calculating the upper limit of p-value in hypothesis testing, using a bootstrap predictive distribution. To determine the sample size of a replication study, this study proposes thought experiments by simulating boosted bootstrap samples of different sizes from given observations. The method is illustrated for the cases of two-group comparison and multiple linear regression. This study also addresses the reproducibility of the points in the given 95% confidence interval. Numerical examples show that the center point is covered by 95% confidence intervals generated from bootstrap resamples. However, end points are covered with a 50% chance. Hence this study draws the graph of the reproducibility rate for each parameter in the confidence interval.

• The Journal of Engineering Geology
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• v.9 no.1
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• pp.31-43
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• 1999

This study aims to quantify the distribution characteristics of the fracture system for the numerical modeling of groundwater flow in the north-eastern area of Yosu peninsula. The study area is composed mainly of volcanic rocks and granite. The regional and site scale lineament in the range of magnitude Order 1 to Order 3 were analyzed from the geologic map, air-photograph and shaded relief map. The geometric parameter of Order 4 fracture system was acquired from the scanline survey on the ground surface. There is a similar trend in the preferred orientation between the regional lineament and the Order 4 fracture system except the Set 4 of Order 4 fracture system which is not prominent in the type. That is classified to three fracture sat of high dip angle and one of ow dip angle. From the lineament trend. The orientation of Order 4 fracture system has similar characteristics in each rock termination mode analysis, it is considered that the fracture system was developed systematically and sequentially from Set 1 to Set 4 Filling materials are distinct relatively in low dip angle set. The fracture spacing follows to lognoral distribution and the fracture frequency corrected by the modified Terzaghi correction ranges from 0.38 to 1.01 per mater in each fracture set. The fracture trace lenght also follows to lognormal distribution and ranges from 2.9m to 3.7m in each fracture set.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.1
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• pp.74-83
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• 1995

To estimate the parameters of a mathematical model of fishes' swimming behavior, the behavior in a experimental water tank was observed and analyzed using the video monitoring system. The tank was equipped with vertical circulation system, and measured $3,500L\;{\times}\;1,500B\;{\times}\;1,000H\;mm$ at flow channel and $1,200L\;{\times}\;900B\;{\times}\;500H\;mm$ at observational part. Rainbow trout, salmo gairdnerii were used as experimental fishes. Their swimming behavior in the tank was observed by the monitoring system, and the positions of every individual were checked at 0.5 second intervals by the image processing of recorded pictures for 5 minutes. The mean swimming speed calculated from the time series data of positions of every individual ranged from 2.5BL cm/sec to 2.9BL cm/sec at the stagnated flow. The mean swimming speed of 10 individuals in a school increased according to the flow speed. The mean swimming depth ranged from 17 cm to 38 cm even though it changed irregularly at the stagnated flow and gradually became stable according to the increase of flow speed. In the present study, the mean distance of individuals from wall of the tank varied from 17.6cm to 21.4cm. The mean distance between the nearest individual varied from 0.4BL cm to 0.7BL cm when 10 individuals in a school were observed. The mean dimension of fish schools became enlarged in all directions according to increase in the number of individuals, and as flow speed increased the horizontal dimension of fish schools expanded while their vertical dimension decreased.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.2
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• pp.110-118
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• 2002

The element free Galerkin method has been suggested by Belyschko, etc. it is applied for linear elastic analysis of solid problems and its convergence characteristics and stability are shown according to the weight function, influence domain and scattered points. The various numerical examples are performed to check the efficiency of 1D EFG and 2D EFG program by changing factors. As a result it have the best results when it used the cubic spline weight function and the scaling parameter d$_{max}$=2. These programs were developed by mixed language programming method using Visual Basic and the C language. so it is fast and efficient. and visually shown the result.t.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.3
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• pp.160-163
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• 2008

$CO_2$ ocean sequestration is being considered as a way to earn a frame of time to change other industrial life pattern to overcome the global warming crisis. The method is to dilute the captured $CO_2$ into ocean by ejecting the liquefied $CO_2$ through nozzles. The main issue of such method is the effectiveness and safety, and in both problems the rising speed of those LCO2 droplet is the key parameter. In this paper, the rising speed of LCO2 droplets is numerically studied including the effect of the surfactant which can be residing along the density interface of the droplets. A front tracking method with a simple surface tension model is developed and the rising speed of the droplets is carefully investigated with varying the various parameters. It is demonstrated that the variable surface tension can change the deformation of the droplet, the flow near the interface, and the rising speed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.265-274
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• 2018

The increasing use of curved beams in buildings, vehicles, ships, and aircraft has prompted studies directed toward the development of an accurate method for analyzing the dynamic behavior of such structures. The stability behavior of elastic curved beams has been the subject of a large number of investigations. Solutions of the relevant differential equations have been obtained traditionally using standard finite difference or finite element methods. These techniques require a great deal of computer time as the number of discrete nodes becomes relatively large under the conditions of complex geometry and loading. One of the efficient procedures for the solution of partial differential equations is the method of differential quadrature. The differential quadrature method (DQM) has been applied to a large number of cases to overcome the difficulties of the complex algorithms of programming for the computer, as well as the excessive use of storage due to the conditions of complex geometry and loading. The in-plane buckling of curved beams considering the extensibility of the arch axis was analyzed under uniformly distributed radial loads using the DQM. The critical loads were calculated for the member with various parameter ratios, boundary conditions, and opening angles. The results were compared with the precise results by other methods for cases, in which they were available. The DQM, using only a limited number of grid points, provided results that agreed very well (less than 0.3%) with the exact ones. New results according to diverse variations were obtained, showing the important roles in the buckling behavior of curved beams, and can be used in comparisons with other numerical solutions or with experimental test data.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.437-444
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• 2020

This study was focused on the stabilization of surge motions of a moored vessel under irregular head seas. A two-point moored vessel shows strong non-linearity even in regular sea, owing to its inherent non-linear restoring force. A long-crested irregular wave is subjected to the vessel system, resulting in more complex nonlinear behavior of the displacement and velocities than in the case of regular waves. Sliding mode control (SMC) is implemented in the moored vessel to control both surge displacement and surge velocity. The SMC can provide a closed-loop system with performance and robustness against parameter uncertainties and disturbances; however, chattering is the main drawback for implementing SMC. The goal of minimizing the chattering and state convergence with accuracy is achieved using a quasi-sliding mode that approximates the discontinuous function via a continuous sigmoid function. Numerical simulations were conducted to validate the effectiveness of the proposed control algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.7
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• pp.754-764
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• 2016

To understand and analyze SNS(Social Network Service) two important classes of networks, small-world and scale-free networks have gained a lot of research interests. In this study, a generalized network generation method is developed, which can produce small-world network, scale-free network, or network with the properties of both small-world and scale-free by controlling two input parameters. By tuning one parameter we can represent the small-world property and by tuning the other one we can represent both scale-free and small-world properties. For the network measures to represent small-world and scale-free properties clustering coefficient, average shortest path distance and power-law property are used. Using the model proposed in this study we can have more clear understanding about relationships between small-world network and scale-free network. Using numerical examples we have verified the effects of two parameters on clustering coefficient, average shortest path distance and power-law property. Through this investigation it can be shown that small-world network, scale-free network or both can be generated by tuning two input parameters properly.

• Journal of the Korean Society for Railway
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• v.12 no.1
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• pp.31-38
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• 2009

The selection of the support system is an important design parameter in design and construction of the tunnel using the new Australian tunnel method. It is a common practice to select the support based on the rock mass grade, in which the rock mass is classified into five rock groups. The method is applicable if the characteristics of the rock mass are uniform in the direction of tunnel excavation. However, such case is seldom encountered in practice and not applicable when the properties vary along the longitudinal direction. This study performs comprehensive three dimensional finite difference analyses to investigate the ground deformation pattern for cases in which the rock mass properties change in the direction of the tunnel axis. The numerically calculated displacements at the tunnel crown show that the displacement is highly dependent on the stiffness contrast of the rock masses. The results strongly indicate the need to select the support type $0.5{\sim}1.0D$ before the rock mass boundary. The paper proposes a new guideline for selecting the support type based the results of the analyses.