• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.130-136
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• 1998

This paper develops an efficient algorithm for the minimum distance calculation between two general polyhedra(convex and/or concave) in three-dimensional space. The polyhedra approximate objects using flat polygons which composed of more than three vertices. The algorithm developed in this paper basically computes minimum distance between two polygons(one polygon per object) and finds a set of two polygons which makes a global minimum distance. The advantage of the algorithm is that the global minimum distance can be computed in any cases. But the big disadvantage is that the minimum distance computing time is rapidly increased with the number of polygons which used to approximate an object. This paper develops a method to eliminate sets of two polygons which have no possibility of minimum distance occurrence, and an efficient algorithm to compute a minimum distance between two polygons in order to compensate the inherent disadvantage of the algorithm. The correctness of the algorithm is verified not only comparing analytically calculated exact minimum distance with one calculated using the developed algorithm but also watching a line which connects two points making a global minimum distance of a convex object and/or a concave object. The algorithm efficiently finds minimum distance between two convex objects made of 224 polygons respectively with a computation time of about 0.1 second.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1876-1879
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• 1997

This paper developes an efficient algorithm for the minimum distance calculation between general polyhedra(convex and/or concave). The polyhedron approximates and object using flat polygons which composed of more than three veritices. The algorithm developed in this paper basically computes minimun distance betwen two convex polygons and finds a set of polygons whcih makes a global minimum distance. The advantage of the algorithm is that the global minimum distance can be computed in any cases. But the big disadvantage is that minimum distance computing time is repidly increased with the number of polygons which used to approximate an object. This paper developes a method to eliminate unnecessary sets of polygons, and an efficinet algorithm to compute a minimum distance between two polygons in order to compensate the inherent disadvantage of the algorithm. It takes only a few times iteration to find minimum distance for msot polygons. The correctness of the algortihm are visually tested with a line which connects two points making a global minimum distance of simple convex object(box) and concave object(pipe). The algorithm can find minimum distance between two convex objects made of about 200 polygons respectively less than a second computing time.

• The Journal of the Acoustical Society of Korea
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• v.3 no.1
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• pp.25-35
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• 1984

This paper analysis the Dynamic Time Warping algorithms for time normalization of speech pattern and discusses the Dynamic Programming algorithm for spoken Korean isolated digits recognition. In the DP matching, feature vectors of the reference and test pattern are consisted of first three formant frequencies extracted by power spectrum density estimation algorithm of the ARMA model. The major differences in the various DTW algorithms include the global path constrains, the local continuity constraints on the path, and the distance weighting/normalization used to give the overall minimum distance. The performance criterias to evaluate these DP algorithms are memory requirement, speed of implementation, and recognition accuracy.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.847-851
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• 2016

Due to global warming it is estimated that the arctic ocean route will be avaliable and traffic will increase by approximately year 2030. However, most navigation in the arctic is based on the ice breaker captains'orders, there is no exact measurement of convoy speed and distance between ships. So, this research was conducted to find out the minimum safe separation distance and minimum breaking distance via ship controling simulations, and the results are as stated. For breaking distances, for ships that have a lead distance which is 2~4 times the width of the ship and traveling less than 7 knots, crash astern and crash astern & hard rudder showed no significant difference. But ships traveling at 10 knots there was a decrease in breaking distance of 1L, from 3.5L to 2.5L. By analyzing 10 subject ships by crash astern the breaking distance for 5 knots is 0.98L~1.8L, for 8 knots is 1.9L~4.0L. The minimum safe separation distance in narrow sea-ways is 6L, but as the arctic sea-way is only one-way 3L is required. As the result, it is found that in the arctic the safe escort speed is less than 5 knots, if the escort speed is 8knots or more and by using crash astern & hard rudder to break the safe distance should be kept at 3.4L.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.208-213
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• 2011

This paper analyzes potential interference effects of Ultra Wide Band(UWB) on Global Positioning System(GPS) which is providing safety service. For the interference analysis, positioning error method is used to determine the minimum protection distance to meet positioning error of 2.5 m below and Minimum Coupling Loss(MCL) method is used to determine the required protection ratio(I/N) from the protection distance of UWB transmitter and GPS receiver to meet positioning error of 2.5 m below. In a result, the minimum protection distance to meet positioning error of 2.5 m below was about 10 m and the protection ratio to meet positioning error 2.5 m below was -20 dB. The protection ratio proposed in this paper is the same value of the protection ratio of safety service proposed by ITU-R. The obtained protection ratio can be used for the protection standard of domestic GPS system for the safe of life service.

• Bulletin of the Korean Chemical Society
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• v.26 no.9
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• pp.1421-1426
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• 2005

The stationary point structures and relative energies between them as well as binding energies of $(CO)_2$ have been investigated at the CCSD(T) level using the correlation-consistent basis sets aug-cc-pVXZ(X=T,Q,5). It is found that while the equilibrium structure corresponds to the C-bonded T-shaped configuration with intermolecular distance of 4.4 $\AA$, there exists another minimum, slightly higher in energy ($\sim$10 $cm^{-1}$) than the global minimum, corresponding to the O-bonded T-shaped configuration with the intermolecular distance of 3.9 $\AA$. The CCSD(T) basis set limit binding energy of $(CO)_2$ is estimated to be 132 $cm^{-1}$.

• Journal of the Optical Society of Korea
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• v.19 no.1
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• pp.95-101
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• 2015

To accurately extract absolute distance information from a self-mixing interferometry (SMI) signal, in this paper we propose an approach based on a particle swarm optimization (PSO) algorithm instead of frequency estimation for absolute distance. The algorithm is utilized to search for the global minimum of the fitness function that is established from the self-mixing signal to find out the actual distance. A resolution superior to $25{\mu}m$ in the range from 3 to 20 cm is obtained by experimental measurement, and the results demonstrate the superiority of the proposed approach in comparison with interpolated FFT. The influence of different external feedback strength parameters and different inertia weights in the algorithm is discussed as well.

• The Transactions of the Korea Information Processing Society
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• v.7 no.10
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• pp.3280-3289
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• 2000

In this paper,we propose a novel technoque of improving volume rendering quality and speed by integrating volume data and global shape information together. The selective volume rendering method is to generate distance transformed volume using a distance transform to determine the minimum distance to the neaest intercsting part and then render it. The shape information prevents from object occlusions come from similar intensity of each object. Thus it provides effective visual results that enable to get a clear understanding of complex structures. We show the results of selective volume rendering method for left ventricle and right ventricle ans well as the results of selective sampling methods depending on the interpolation from EBCT cardiac images. Our method offers an accelerated technique to accurately visuahze the surfaces of devined objects segmented from the volume.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.12
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• pp.204-213
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• 1999

This paper suggests a numerical method of finding optimal geometric path and minimum-time motion for a manipulator arm. To find the minimum-time motion, the optimal geometric path is searched first, and the minimum-time motion is searched on this optimal path. In the algorithm finding optimal geometric path, the objective function is minimizing the combination of joint velocities, joint-jerks, and actuator forces as well as avoiding several static obstacles, where global search is performed by adjusting the seed points of the obstacle models. In the minimum-time algorithm, the traveling time is expressed by the linear combinations of finite-term quintic B-splines and the coefficients of the splines are obtained by nonlinear programming to minimize the total traveling time subject to the constraints of the velocity-dependent actuator forces. These two search algorithms are basically similar and their convergences are quite stable.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1054-1059
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• 2005

The artificial potential method uses a potential field to guide a robot from a start to a goal configuration respectively. The potential field consists of attractive potential used to pull a robot toward a goal and repulsive potential to keep it away from obstacles. However, there are two problems concerning local minimum and computational cost to be resolved in conventional artificial potential methods. This study proposes a method utilizing a spline surface that interpolates arbitrary boundaries and a domain reduction method that reduces the unnecessary area. The proposed spline surface interpolates arbitrary shaped boundaries and is used as an artificial potential to guide a robot for global motion planning of a mobile robot. A reduced domain process reduces the unnecessary domain. We apply a distance-weighted function as such a function, which blends distances from each boundary with a reduction in computational time compared with other analytical methods. As a result, this paper shows that an arbitrary boundary spline surface provides global planning and a domain reduction method reduces local minimum with quick operation.