• Journal of applied mathematics & informatics
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• v.28 no.5_6
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• pp.1347-1358
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• 2010

An upright drawing of a planar graph G on k layers is a planar straight-line drawing of G, where the vertices of G are placed on a set of k horizontal lines, called layers and no two adjacent vertices are placed on the same layer. There is a previously known algorithm that decides in linear time whether a planar graph admits an upright drawing on k layers for a fixed value of k. However, the constant factor in the running time of the algorithm increases exponentially with k and makes it impractical even for k = 3. In this paper, we give a linear-time algorithm to examine whether a biconnected planar graph G admits an upright drawing on three layers and to obtain such a drawing if it exists. We also give a necessary and sufficient condition for a tree to have an upright drawing on three layers. Our algorithms in both the cases are much simpler and easier to implement than the previously known algorithms.

• The Journal of the Acoustical Society of Korea
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• v.43 no.2
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• pp.234-242
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• 2024

We propose a passive sonar signal classification algorithm using Graph Neural Network (GNN). The proposed algorithm segments spectrograms into image patches and represents graphs through connections between adjacent image patches. Subsequently, Graph Convolutional Network (GCN) is trained using the represented graphs to classify signals. In experiments with publicly available underwater acoustic data, the proposed algorithm represents the line frequency features of spectrograms in graph form, achieving an impressive classification accuracy of 92.50 %. This result demonstrates a 8.15 % higher classification accuracy compared to conventional Convolutional Neural Network (CNN).

• Fashion & Textile Research Journal
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• v.9 no.4
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• pp.418-424
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• 2007

The purpose of this study is to propose a standard of converting 3D shape of men in twenties to 2D patterns. This can be a basis for scientific and automatic pattern making for high quality custom clothes. Firstly, representative 3D body shape of men was modeled. Then the 3D model was divided into 3 shells, front, side and back. Among them, the front shell was divided into 4 blocks by bust line and princess line. Secondly, curves are generated on each block according to matrix combination by grid method. Then triangles were developed into 2D pieces by reflecting the 3D curve length. The grid was arranged to maintain outer curve length. Next, the area of developed pieces and block were calculated and difference ratio between the block area and the developed pieces' area is calculated. Also, area difference ratio by the number of triangles is calculated. The difference ratio was represented as graphs and optimal section is selected by the shape of graphs. The optimal matrix was set considering connection with other blocks. Curves of torso upper front shell were regenerated by the optimal matrix and developed into pieces. We validated it's suitability by comparing difference ratio between the block area and the developed pieces' area of optimal section. The results showed that there was no significant difference between block area and the pieces' area developed by optimal matrix. The optimal matrix for 2D developing could be characterized as two types according to block's shape characteristics, one is affected by triangle number, the other is affected by number of raws more than columns. Through this study, both the 2D pattern developing from 3D body shape and 3D modeling from 2D pattern is possible, so it's standardization also possible.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1336-1341
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• 2011

The pantograph-overhead contact line system is an interface that supplies power to high-speed trains used in many countries including Korea. Due to the fact that power is supplied through direct contact between contact wires and contact strips, wear may occur, increasing the possibility of accidents over periods of time. Therefore, there is a need to establish methods of effectively extracting safety related parameters. In this paper, an image processing based method that calculates and draws graphs of a pantograph's dynamic stagger is proposed. To assess reliability, the results were compared with data collected from conventional maintenance vehicles.

• Steel and Composite Structures
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• v.22 no.2
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• pp.411-427
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• 2016

In this study, by using finite element non-linear static analysis and comparing it with experimental models, the buckling and post-buckling behavior of bracing gusset plates has been investigated. The effects of such parameters as dimension and thickness of the gusset plate and the influence of position of the bracing member on the behavior of gusset plate have been examined. The results of the analyses clearly suggest that capacity, buckling and post-buckling behaviors of gusset plates depend on the position of the bracing splice plate with respect to the free bending line as well as on the size and thickness of the gusset plate. Also, with respect to numerical analysis results, some practical graphs for the calculation of buckling capacity of gusset plate connections are presented. For steel structures, the proposed method is apparently more accurate than available code procedures.

• Journal of the Korean Chemical Society
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• v.63 no.6
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• pp.473-485
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• 2019

In this study, we investigated the differences of graph constructed by middle school students in daily-life and scientific contexts according to the views on the nature of scientific measurement. A test consisting of three similar data sets regarding daily-life and scientific contexts was developed, and administered to 151 ninth graders. They were expected to construct proportional, inverse-proportional, and increasing and become constant form of graphs for each data set. Graphs constructed were analyzed in the aspects of constructing a trend line (types of a trend line, interpolation/extrapolation), selecting axes variables, scaling axes, and plotting points. Analyses of the results revealed that the students with set paradigm tended to construct a curved trend line, while those with point paradigm constructed a broken trend line in inverse-proportional graph questions. In the aspects of interpolation/extrapolation, most students with set paradigm performed both interpolation and extrapolation better than those with point paradigm in scientific context. Most students with set paradigm performed both interpolation and extrapolation regardless of contexts, while the proportion of interpolation of those with point paradigm was higher in scientific context than in daily-life context. In selecting axes variables, scaling axes, and plotting dots, there were no statistically significant differences between set and point paradigms. On the bases of the results, educational implications for improving graph construction skills of middle school students are discussed.

• Journal of the Korean Society of Clothing and Textiles
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• v.14 no.4 s.36
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• pp.245-251
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• 1990

The purposes of the study were to efplain the independent influences of Asthetic Expression and Fashion on aesthetic evaluation in the clothing, to examine which in more important aesthetic components such as line/style, color, textile and detail in aesthetic evaluation in the clothing. Data were obtained from 221 female students living in Seoul area by eight photo-graphs of clothed bodies and a questionnaire. The data were analysied by Pearson's correlation, Analysis of valiables, scheffe-test and Regression analysis. The results of the study were as follows; 1. In the aesthetic evaluation of clothing, the $59.30\%$ of the total variance was explained by Aesthetic Expression, the $20.91\%$ of the total variance was explained by Fashion and $59.68\%$ of the total variance were explained by Aesthetic Expression and Fashion. More important variable of aesthetic evaluation was found to be an Aesthetic Expression. 2. Among aesthetic components such as line/style, color, textile and detail in aesthetic evaluation of the clothing, such general aspects as color and line/style were perceived at first and then specific ones like textile and detail.

• Journal of The Korean Association For Science Education
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• v.22 no.4
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• pp.768-778
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• 2002

Science teachers often suppose that students are able to know the symbolical meaning of graphs when they see the graphs. But such a assumption is not based on the firm theories but a mere image. And we need to search them for holding the abilities to construct and to interpret. In addition, unfortunately, many researchers show that they scarcely have the graphing skills. And then, The Test of Graphing in Science(TOGS) was administered to 535 7th to 12th graders, for we search them for holding the graphing abilities to some degree. Though the higher grade, the better score, they lack the first three among 9 objectives of TOGS which are scaling axes, assigning variables to the axes, using a best fit line, plotting points, translating a graph that displays the data, selecting the corresponding value for y(or x), interrelating/extrapolating graphs, describing the relationship between variables, interrelating the results of the two graphs. It was concluded from this that subjects' graph construction is lower than their graph interpretation in graph skills. It suggests that school science have a bias toward graph interpretation. This tendency represents more strikingly in the case of upper students in TOGS than the others'.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.3
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• pp.193-208
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• 2021

The characteristics of the microcrack lengths(①), microcrack spacings(②) and Brazilian tensile strengths(③) related to the six directions of rock cleavages(H2~R1) in Geochang granite were analyzed. First, the 18 cumulative graphs for the above three major factors representing unique characteristics of the rock cleavages were made. Through the general chart for these graphs classified into three planes and three rock cleavages, the 28 parameters on the length, spacing and Brazilian tensile strength have been determined. The results of correlation analysis among these parameters are summarized as follows. Second, the above parameters were classified into six groups(I~VI) according to the sorting order on the magnitude of parameter values among three rock cleavages and three planes. The values of parameters belonging to group I and II are in order of R(rift) < G(grain) < H(hardway) and H < G < R. The values of the 8 parameters on the length of line(os₂, 𝚫s, 𝚫L and oS^mean), the exponent(λ_L^mean and λ_S^mean), the slope(a^mean) and the anisotropy coefficient (An^mean) are in order of R < G < H and H'(hardway plane) < G'(grain plane) < R'(rift plane). Third, the noticeable differences in distribution patterns among the six types of charts for three planes and three rock cleavages are as follows. From the chart for three planes, the values of 𝚫L, 𝚫s and 𝚫σ_t, corresponding to the distance between two points where the two fitting lines meet on the X-axis, increase in the order of R' < H' < G'. In particular, the two graphs of R2 and G2 related to the length and Brazilian tensile strength are almost parallel to each other and show the distribution characteristics of hardway plane. Among the graphs related to the Brazilian tensile strength, the overall shape for hardway plane is similar to that for grain. From the chart for three rock cleavages, the slopes of the graphs related to the length increase in the order of R < G < H, while those of the graphs related to the spacing and Brazilian tensile strength decrease in the order of R < G < H. Lastly, the characteristics of variation among the six rock cleavages, the three planes and the three rock cleavages were visualized through the correlation chart among the above parameters from this study.

• Communications of the Korean Mathematical Society
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• v.35 no.1
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• pp.1-12
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• 2020

A pathos block line cut-vertex graph of a tree T, written P BL_c(T), is a graph whose vertices are the blocks, cut-vertices, and paths of a pathos of T, with two vertices of P BL_c(T) adjacent whenever the corresponding blocks of T have a vertex in common or the edge lies on the corresponding path of the pathos or one corresponds to a block B_i of T and the other corresponds to a cut-vertex c_j of T such that c_j is in B_i; two distinct pathos vertices P_m and P_n of P BL_c(T) are adjacent whenever the corresponding paths of the pathos P_m(v_i, v_j) and P_n(v_k, v_l) have a common vertex. We study the properties of P BL_c(T) and present the characterization of graphs whose P BL_c(T) are planar; outerplanar; maximal outerplanar; minimally nonouterplanar; eulerian; and hamiltonian. We further show that for any tree T, the crossing number of P BL_c(T) can never be one.