• Korean Journal of Mathematics
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• v.13 no.2
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• pp.123-126
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• 2005

This paper is a sequel to our earlier research on biplanar drawings [4] and biplanar crossing numbers [3]. The biplanar crossing number $cr_2$(G) of a graph G is $min\{cr(G_1+cr(G_2)\}$, where $cr$ is the planar crossing number and $G =G_1{\cup}G_2$. In this paper we show that $cr_2(G){\leq}{\frac{3}{8}}cr(G)$.

• Kyungpook Mathematical Journal
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• v.55 no.3
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• pp.741-752
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• 2015

We introduce the warping crossing polynomial of an oriented knot diagram by using the warping degrees of crossing points of the diagram. Given a closed transversely intersected plane curve, we consider oriented knot diagrams obtained from the plane curve as states to take the sum of the warping crossing polynomials for all the states for the plane curve. As an application, we show that every closed transversely intersected plane curve with even crossing points has two independent canonical orientations and every based closed transversely intersected plane curve with odd crossing points has two independent canonical orientations.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.11
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• pp.1782-1793
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• 1989

Stroke crossing number, syntactic pattern recognition procedure, top down recognition structure, and heuristic approach are studied for the Korean text recognition. We propose new algorithms: 1)Korean vowel seperation using limited scanning method in the Korean characters, 2) extracting strokes using stroke width method, 3) stroke crossing number and its properties, 4) average, standard deviation, and mode of stroke crossing number, and 5) classification and recognition methods of limited chinese character. These are studied with computer simuladtions and experiments.

• Journal of Forest and Environmental Science
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• v.34 no.2
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• pp.136-141
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• 2018

The purpose of this study is to compare the bird crossing of roads by type (Expressway 1, railroad-provincial road and Highway 4) and the crossing of roads according to the size of birds. The greatest number of avian species and individuals crossing road per 10 minutes were found on railroad-provincial road ($8.96{\pm}1.92$ and $29.33{\pm}11.94$, respectively), while the lowest number of avian species and individuals were found on Expressway 1 ($2.96{\pm}1.04$ and $6.13{\pm}2.89$, respectively), which has the widest width. In addition, the number of small-sized bird (<20 cm) crossing the Expressway 1, railroad-provincial road, and Highway 4 was lower than that of the medium-sized bird (${\geq}20cm$). Current wildlife crossing structures have been focused on mammals, amphibians and reptiles, but future structures should also consider birds.

• Journal of Korean Society of Transportation
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• v.13 no.2
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• pp.43-58
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• 1995

This paper discusses some of the results of investigation of railroad-highway grade crossing accidents and accident-related inventory information that was collected from the Pusan District Office of the Korean National Railroads. Established statistical techniques were applied to tabulated data to obtain an accident prediction equation that estimates the expected probability of accidents at each crossing under various grade crossing situations. It was found that the most significant factor that influences the railroad crossing accidents was flagger. The other factors were train and traffic volumes, number of tracks. crossing angle, maximum timetable train speed, algebraic grade difference, and lighting facility. No significant effects was identified with railroad crossing gates. The results of the analysis and the uses of the prediction equation for the development of warrants for safety improvements are also discussed.

• Bulletin of the Korean Mathematical Society
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• v.55 no.3
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• pp.799-808
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• 2018

We generalize some of the congruences in [20] to periodic knotted trivalent graphs. As an application, a criterion derived from one of these congruences is used to obstruct periodicity of links of few crossings for the odd primes p = 3, 5, 7, and 11. Moreover, we derive a new criterion of periodic links. In particular, we give a sufficient condition for the period to divide the crossing number. This gives some progress toward solving the well-known conjecture that the period divides the crossing number in the case of alternating links.

• Kyungpook Mathematical Journal
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• v.59 no.4
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• pp.797-820
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• 2019

For every tree T, we introduce a topological invariant, called the T-cross-index, for connected graphs. The T-cross-index of a graph is a non-negative integer or infinity according to whether T is a tree basis of the graph or not. It is shown how this cross-index is independent of the other topological invariants of connected graphs, such as the Euler characteristic, the crossing number and the genus.

• Kyungpook Mathematical Journal
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• v.57 no.2
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• pp.331-360
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• 2017

Unknotting numbers for torus knots and links are well known. In this paper, we present a new approach to determine the position of unknotting number crossing changes in a toric braid such that the closure of the resultant braid is equivalent to the trivial knot or link. Further we give unknotting numbers of more than 600 knots.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.5
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• pp.883-891
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• 1994

In this paper, we introduce new thinning algorithm which is useful for handwritten Korean character by using pixel directivity. At first, the directivity detection is performed before thinning. Each pixel is classified into the straight line of the oblique line based on its directivity. The algorithm using Rutovitz corossing number is applied to the straight line. And the algorithm using Hilditch crossing number is applied to the oblique line. The proposed algorithm is compared with six convention algorithms. Comparison criteria are similarity, noisy branch, and phoneme segmentation rate. Experiments with 570 characters have been conducted. Experimental result shows that the proposed algorithm is superior to six conventional algorithm with respect to similarity and phoneme segmentation rate.

• International Journal of Highway Engineering
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• v.19 no.4
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• pp.69-78
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• 2017

PURPOSES : In this study, we analyzed the road crossing behavior of older pedestrians on a mid-block signalized crosswalk, and compared it to that of younger pedestrians. In addition, we analyzed the correlation between accidents involving older pedestrians while crossing roads and their behavioral characteristics. Finally, we confirmed the reasons for an increase in accidents involving older pedestrians. METHODS : First, 30 areas with the highest incidence of accidents involving older pedestrians while crossing roads were selected as target areas for analysis. Next, we measured the start-up delay (the time elapsed from the moment the signal turns green to the moment the pedestrian starts walking) and head movement (the number of head turns during crossing a road) of 900 (450 older and 450 younger) pedestrians. The next step was to conduct a survey and confirm the differences in judgment between older and younger pedestrians about approaching vehicles. Finally, we analyzed the correlation between the survey results and traffic accidents. RESULTS : The average start-up delay and head movement of the older pedestrians was 1.58 seconds and 3.15 times, respectively. A definite correlation was obtained between head movement and the frequency of pedestrian traffic accidents. The results of our survey indicate that 17.3% of the older pedestrians and 7.8% of the younger pedestrians have a high crash risk. CONCLUSIONS : Behavioral characteristics of older pedestrians were closely correlated with accidents involving older pedestrians while crossing roads in mid-block signalized crosswalks. Our study indicates that in order to reduce the number of accidents involving older pedestrians, it is necessary to develop an improvement plan including measures such as installation of safety facilities taking the behavioral characteristics of older pedestrians into consideration and their safety education.