• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11A
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• pp.1946-1956
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• 2001

In this paper, we propose a novel 2-D partial matching algorithm based on model-based stochastic analysis of feature correspondences in a relation vector space, which is quite robust to shape variations as well as invariant to geometric transformations. We represent an object using the ARG (Attributed Relational Graph) model with features of a set of relation vectors. In addition, we statistically model the partial occlusion or noise as the distortion of the relation vector distribution in the relation vector space. Our partial matching algorithm consists of two-phases. First, a finite number of candidate sets areselected by using logical constraint embedding local and structural consistency Second, the feature loss detection is done iteratively by error detection and voting scheme thorough the error analysis of relation vector space. Experimental results on real images demonstrate that the proposed algorithm is quite robust to noise and localize target objects correctly even inseverely noisy and occluded scenes.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.15-19
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• 2006

GPS has been increasingly exploited to provide positioning and navigation solutions for a variety of applications. In vessel berthing application, however, there are stringent requirements in terms of positioning accuracy, availability and integrity that cannot be satisfied by GPS alone. This is because the performance of satellite-based positioning and navigation systems are heavily dependent on both the number and the geometric distribution of satellite tracked by receivers. Due to the limited number of GPS satellites, a sufficient number of ‘visible’ satellites cannot be sometimes guaranteed. This paper discusses some issues associated with the implementation of ground-based pseudolite augmentation for vessel berthing. Pseudolite means small transmitter that transmits GPS-like signals in local area. Actually, pseudolite can play three different roles in GPS augmentation scheme, depending on the operational conditions. Firstly, in the case of kinematic GPS operation where there are no signal blockages, and more than five satellites are available, additional pseudolites strengthen the GPS satellite-pseudolite geometry, and more accurate and reliable positioning solution can be achieved. Secondly, in the case when there are adverse GPS operational environments in which the number of tracked satellites is less than four, pseudolites can complement the GPS signals. In the third case, GPS signals are completely unavailable, such as when operated indoor. In such cases the pseudolites can replace the satellite constellation. However, the first role will be considered in this paper, since more than four satellite signals can usually be tracked in most marine applications. This paper presents that the pseudolite-augmented precise positioning system can provides continuous centimeter-level positioning accuracy through comparison analysis of RDOP simulation result of the GPS satellite constellation and the pseudolite-augmented GPS satellite constellation.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.8 no.3
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• pp.13-22
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• 2012

According to recent research on leak-rate estimates to assess rupture probabilities of nuclear piping which contains a circumferential surface/through-wall cracks due to PWSCC, i.e., xLPR (Extremely Low Probability of Rupture) program, it has been revealed that the use of crack shape with an idealized circumferential through-wall crack during actual crack growth can lead to overestimate of the leak-rate. Thus, for accurate estimation of the leak-rate during crack growth, the more realistic crack shape that can simulate the crack shape transition from surface crack to through-wall crack should be used. In this context, in the present study, the elastic crack opening displacement of slanted circumferential through-wall crack in thick-walled cylinder was proposed based on 3-dimensional elastic finite element fracture mechanics analyses. To propose the elastic crack opening displacement of slanted circumferential through-wall crack in thick-walled cylinder, the geometric variables affecting crack opening displacement, i.e., thickness of cylinder, reference inner crack length and slant crack ratio were systematically varied. In terms of loading conditions, axial tension, global bending moment and internal pressure were considered. The present results can be applied to calculate the leak-rate considering more realistic crack shape transition from surface crack to idealized through-wall crack, and can be expected to enhance current leak-rate estimation scheme, for instance, in xLPR program etc.

• Journal of Soil and Groundwater Environment
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• v.17 no.5
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• pp.1-9
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• 2012

The purpose of ecological risk assessment in soil ecosystem is to protect ecological receptors and to provide a scheme of efficient management for soil contaminants. Developed countries have already prepared the methodologies of ecological risk assessment by considering their soil properties, land use, and ecological receptors. In this study, we compared the soil ecological risk assessment processes in the similarity and differences in methodology. Four countries, except for USA, adjusted the toxicological data for ecological risk assessment, based on their representative soil properties because the soil properties affect toxic effects to ecological receptors. The soil ecological risk assessment methodology of Netherlands and UK was based on 'Technical guidance document on risk assessment (TGD)' of European Chemical Bureau (ECB). Australia, USA, and Canada developed their autonomous methodology. In the Netherlands, UK, Australia, and Canada, they employed the species sensitivity distribution (SSD) approach if sufficient toxicity data are available. The USA determined the ecological soil screening level by obtaining the geometric mean of toxicological data for three species. Furthermore, all countries consider secondary poisoning in their soil ecological risk assessment. The latest risk assessment methodology of soil ecosystem that this study investigated can be used to explore what Korea needs to develop the Korean ecological risk assessment methodology of soil ecosystem in the future.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.2
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• pp.19-25
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• 2004

The linear analysis for the balance of linear momentum of a structure is relatively easy to perform, but the error becomes large when the structure experiences large deformation. Therefore, the material and geometric nonlinearity need to be considered for the precise calculations in that case. The plastic flow of a ductile steel-like metal mainly transforms its dissipated mechanical energy into heat, which transfers under the first and second law of thermodynamics. This heat increases the temperature of the material and the strength of the material decreases accordingly, which affects mechanical behavior of the given structure. This paper presents a finite-strain thermo-elasto-plastic steel model. This model can handle large deformation and thermal load simultaneously, which is common during earthquake periods. Two 3-dimensional finite element analyses verify this formulation.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.164-174
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• 2015

In a real scenario, radiometric change has frequently occurred in the stereo image acquisition process using multiple cameras with geometric characteristics or moving a single camera because it has different camera parameters and illumination change. Conventional stereo matching algorithms have a difficulty in finding correct corresponding points because it is assumed that corresponding pixels have similar color values. In this paper, we present a new method based on the local descriptor reflecting intensity, gradient and texture information. Furthermore, an adaptive weight for local descriptor based on the entropy is applied to estimate correct corresponding points under radiometric variation. The proposed method is tested on Middlebury datasets with radiometric changes, and compared with state-of-the-art algorithms. Experimental result shows that the proposed scheme outperforms other comparison algorithms around 5% less matching error on average.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.287-292
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• 2021

We utilized the isogeometric analysis (IGA) method that uses NURBS basis functions in CAD systems, to account for the geometric exactness of a geometrically exact beam deformation, on a new type of metamaterial, twist-translation coupled structure showing a large twist angle. A two-dimensional unit cell structure was embedded in a cylindrical wall, using free-form deformation and an appropriate interpolation scheme. A parametric study on the effects of the dimensions of the cylinder and the number of cells, on the twisting angle was performed. Furthermore, the mechanism of the twist-translation coupled metamaterial was explored through numerical examples.

• Fashion & Textile Research Journal
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• v.23 no.6
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• pp.726-743
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• 2021

This study tried to examine the fashion design and style of representative K-Pop boy groups BTS and SEVENTEEN appearing on music shows. The data collection was conducted on 4 music programs(Inkigayo, Music Bank, Show! Music Core, M COUNTDOWN) and YouTube(www.youtube.com) for each boy who worked for 5 years from January 2016 to December 2020. Result analysis utilized the stage scenes and music videos of the title songs of BTS and Seventeen. As for the fashion design and style characteristics of BTS, it was found that overall, the color, pattern, and decoration of the bottom were minimized, and the style was changed mainly by the top of the denim pants. As for Seventeen's fashion design and style characteristics, it was analyzed that plain simple slacks, bright and modest chromatic colors, and geometric and stylistic patterns with street retro sensibility were relatively emphasized, and natural and romantic images appeared a lot. As a result of examining the differences in fashion design and style characteristics between BTS and Seventeen, significant differences were found in color, tone, color scheme, material type, material combination, detail, trimming, pattern, accessories, and fashion image. Overall, it was found that both groups minimized the use of decorative elements such as patterns, details, and trimmings.

• Composites Research
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• v.35 no.1
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• pp.31-37
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• 2022

In this study, an optimal structural design framework has been developed for the structural design of composite helicopter blades. The optimal design framework is constructed using PSGA (Particle Swarm assisted Genetic Algorithm), which combines the genetic algorithm and particle swarm optimizer. The optimization process consists of a finite element (FE) modeling over the blade section, two-dimensional (2D) cross-sectional FE analysis, and 1D rotating blade analysis. In the design process, the geometric curves and surfaces are formed using the B-spline scheme while discretizing the sections via a FE mesh generation program Gmsh. The blade cross-sections are created in accordance with the design variables when performing the blade structural analysis. The proposed optimization design framework is applied to a modernization of the HART II (Higher-harmonic Aeroacoustics Rotor Test II) blades. It is demonstrated that an improved blade design is reached through the current optimization framework with the satisfaction of all design requirements set for the study.

• Structural Engineering and Mechanics
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• v.85 no.1
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• pp.105-118
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• 2023

The present work is an attempt to develop a simple and accurate finite element formulation for the assessment of thermal shock/thermally induced vibrations in pretwisted and tapered functionally graded material thin (FGM) blades obtained from Voigt and local representative volume elements (LRVE) homogenization models, based on neutral surface approach. The neutral surface of the FGM blade does not coincide with its mid-surface. A finite element model (FEM) is developed using first-order shear deformation theory (FSDT) and the FGM turbine blade is modelled according to the shallow shell theory. The top and the bottom layers of the FGM blade are made of pure ceramic and pure metal, respectively and temperature-dependent material properties are functionally graded in the thickness direction, the position of the neutral surface also depends on the temperature. The material properties are estimated according to two different homogenization models viz., Voigt or LRVE. The top layer of the FGM blade is subjected to high temperature and the bottom surface is either thermally insulated or kept at room temperature. The solution of the nonlinear profile of the temperature in the thickness direction is obtained from the Fourier law of heat conduction in the unsteady state. The results obtained from the present FEM are compared with the benchmark examples. Next, the effect of angle of twist, intensity of thermal shock, variable chord and span and volume fraction index on the transient response due to thermal shock obtained from the two homogenization models viz., Voigt and LRVE scheme is investigated. It is shown that there can be a significant difference in the transient response calculated by the two homogenization models for a particular set of material and geometric parameters.