• Journal of KIISE:Computer Systems and Theory
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• v.28 no.8
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• pp.399-405
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• 2001

이 논문은 재귀원형군 G(2$^{m}$ , 2$^{k}$ )의 강한 해밀톤 성질을 그래프 이론적 관점에서 고찰한다. 재귀원형군은 [9]에서 제안된 다중 컴퓨터의 연결망 구조이다. G(2$^{m}$ , 2$^{k}$ )가 임의의 정점 쌍 ν, $\omega$를 잇는 길이 ι인 경로를 가지는가 하는 문제를 고려하여, (a) G(2$^{m}$ , 2$^{k}$ )는 ι$\geq$d(ν, $\omega$)을 만족하는 모든 ι에 대해서 길이 ι인 경로를 가지며, (b) G(2$^{m}$ , 4)는 ι$\geq$d(ν, $\omega$)+2인 모든 길이의 경로를 가지며, (c)G(2$^{m}$ , 2$^{k}$ ), k$\geq$3은 길이 d(ν, $\omega$)+2$^{k}$ -3인 경로를 가지지 않는 정점 쌍이 있음을 보인다. 여기서, d(ν, $\omega$)는 ν와 $\omega$ 사이의 거리이다.

• Journal of Korean Society of Transportation
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• v.26 no.1
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• pp.145-153
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• 2008

Existing shortest-path algorithms mainly consider a single attribute. But traveler actually chooses a route considering not single attribute but various attributes which are synthesized travel time, route length, personal preference, etc. Therefore, to search the optimal path, these attributes are considered synthetically. In this study route searching algorithm which selects the maximum utility route using discrete choice model has developed in order to consider various attributes. Six elements which affect route choice are chosen for the route choice model and parameters of the models are estimated using survey data. A multinomial logit models are developed to design the function of route choice model. As a result, the model which has route length, delay time, the number of turning as parameter is selected based on the significance test. We use existing shortest path algorithm, which can reflect urban transportation network such as u-turn or p-turn, and apply it to the real network.

• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.607-613
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• 2015

In order to design M/W(microwave) short backhaul above 10 GHz to meet the increase in mobile traffic demand, the rain attenuation as well as the atmospheric conditions such as Earth bulge and Fresnel zone should be considered. In this paper, the path lengths have been estimated theoretically in various frequency bands using the Korean standard rain rate, and an example of path profile has been analyzed in urban area utilizing spectrum management intelligence system (SMIS). These derived minimum path lengths in various frequency bands are compared to the foreign them, and then will be proposed to improve the Korean minimum path length unitized to 10 km. This paper will provide useful information for microwave engineers in designing a M/W access link, and be utilized to make an efficient usage of high frequency bands for the short mobile broadband backhaul.

• The KIPS Transactions:PartA
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• v.13A no.6 s.103
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• pp.541-544
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• 2006

In a tree with each edge associated with a length and a weight (positive, negative, or zero are possible) we develop an O(nlognloglogn) time algorithm for finding a path such that its sum of weights is maximized and its sum of lengths does not exceed a given value. The previously best-known result is O($nlog^2n$), where n is the number of nodes in the tree.

• Journal of Elementary Mathematics Education in Korea
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• v.19 no.3
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• pp.387-408
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• 2015

The purpose of this research is to analyze the mathematical tasks of length measurement in two different perspectives, the level of cognitive demands and learning trajectories, and restructure the mathematical tasks so that the students' conceptual learning is promoted and students are able to have opportunities to think more broadly. Ten lessons with the restructured mathematical tasks were implemented for a class of 2nd grade elementary students. Also a qualitative and in-depth study was conducted with 4 students of the target group. The study shows that firstly, the restructured tasks requiring high level of cognitive skills, had positive effects in increasing the students' level of thinking and reasoning. Secondly, the tasks modified according to the learning trajectories of Szilag, Clements & Sarama(2013) in length measurement, have proven to promote students' concept learning and elaborate the students' level of thinking.

• Journal of KIISE:Software and Applications
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• v.34 no.11
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• pp.971-983
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• 2007

Cellular Genetic Algorithms(CGAs) are a subclass of Genetic Algorithms(GAs) in which each individuals are placed in a given geographical distribution. In general, CGAs# population space is a regular network that has relatively long characteristic path length and high clustering coefficient in the view of the Networks Theory. Long average path length makes the genetic interaction of remote nodes slow. If we have the population#s path length shorter with keeping the high clustering coefficient value, CGAs# population space will converge faster without loss of diversity. In this paper, we propose Smallest-Small-World Cellular Genetic Algorithms(SSWCGAs). In SSWCGAs, each individual lives in a population space that is highly clustered but having shorter characteristic path length, so that the SSWCGAs promote exploration of the search space with no loss of exploitation tendency that comes from being clustered. Some experiments along with four real variable functions and two GA-hard problems show that the SSWCGAs are more effective than SGAs and CGAs.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.623-629
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• 2018

In this paper, we propose a real-time obstacle detection and avoidance path generation algorithm for UAV. 2-D Lidar is used to detect obstacles, and the detected obstacle data is used to generate real-time histogram for local avoidance path and a 2-D SLAM map used for global avoidance path generation to the target point. The VFH algorithm for local avoidance path generation generates a real-time histogram of how much the obstacles are distributed in the vector direction and distance, and this histogram is used to generate the local avoidance path when detecting near fixed or dynamic obstacles. We propose an algorithm, called modified $RRT^*-Smart$, to overcome existing limitations. That generates global avoidance path to the target point by creating lower costs because nodes are checked whether or not straight path to a target point, and given arbitrary lengths and directionality to the target points when nodes are created. In this paper, we prove the efficient avoidance maneuvering through various simulation experiment environment by creating efficient avoidance paths.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.363-366
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• 2003

이 논문에서는 XML 문서에 대한 경로질의를 효과적으로 처리할 수 있는 색인기법을 제안한다. 제안하는 색인 기법은 문서의 변경에 동적으로 대처하며 단순경로 질의뿐 아니라, 경로의 길이가 주어지지 않는 질의에도 효과적으로 동작한다. 이 논문에서는 제안하는 색인기법을 구현하고 실험을 통해서 경로질의를 처리하는 시간을 측정하여 제안하는 방법의 타당성을 보인다.

• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.50-55
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• 2005

A method for measuring the wavefront error and the modulation transfer function(MTF) of large aperture optics using an unequal path interferometer is presented. A bidirectional shearing interferometer is used for collimation testing of the measurement system. A large aperture Fizeau interferometer with long optical path difference measures the wavefront error of the optics under test by using a $\Phi$ 400 mm off-axis parabolic mirror. The MTF is also measured at the wavelength of the interferometer by changing the laser light into partially incoherent light. Test results of a $\Phi$ 300 mm Cassegrain type satellite telescope made in Korea are presented.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.742-744
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• 2001

이 논문은 n-차원 스타 그래프 S$_{n}$, n$\geq$4에서 정점과 에지 고장의 수가 n-3 이하일 때, 임의의 두 고장이 아닌 정점 사이에 길이가 두 정점의 색이 같으면 n!-2f$_{v}$ -2 이상이고, 색이 다르면 n!-2f$_{v}$ -1 이상인 경로가 존재함을 보인다. 여기서 f$_{v}$ 는 고장인 정점의 수이다. 이 결과를 이용하면 고장의 수가 n-3이하일 때, 임의의 고장이 아닌 에지를 지나는 길이 n!-2f$_{v}$ 이상인 사이클을 설계할 수 있다.