• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.10
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• pp.44-52
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• 1990

A collision-free trajectory planning for two robots with designated paths is considered. The proposed method is based on the concept of decomposing the planning problem into two steps: one is determining coordination of two robots, and the other is velocity planning with determined coordination. Dynamics and maximum allowable joint velocities are also taken into consideration in the whole planning process. The proposed algorithm is converted into numerical calculation version based on neural optimization network. To show the usefulness of proposed method, an example of trajectory planning for 2 SCARA type robot in common workspace is illustrated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.9-16
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• 2014

The localization compensation algorithm for moving objects using the least-squares method is suggested and the performance of the algorithm is analyzed in this paper. The suggested compensation algorithm measures the distance values of the mobile object moving as a constant speed by the TMVS (TWR Minimum Value Selection) method, estimates the location of the mobile node by the trilateration scheme based on the values, and the estimated location is compensated using the least-squares method. By experiments, it is confirmed that the localization performance of the suggested compensation algorithm is largely improved to 58.84% and 40.28% compared with the conventional trilateration method in the scenario 1 and 2, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.110-116
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• 2013

With the recent development of wireless network technologies, there have been increasing usage of variouse position base servies. Position based services basically collect position information of moving object for the utilization of them in real life. Accordingly, new index structures are required to efficiently retrieve the consecutive positions of moving objects. In the paper, we consider volume of Extended Minimum Bounding Rectangles(EMBR) to be determined by average size of range queries. We proposed the methode that split efficiently moving object with long distance between location, and split moving object for decrease searching space an Estimated-Split algorithm that minimizes the volume of MBRs is designed and simulated. Our experimental evaluation confirms the effectiveness and efficiency of our proposed splitting policy.

• Journal of Astronomy and Space Sciences
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• v.25 no.4
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• pp.383-394
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• 2008

We examine geoeffective directional parameters of coronal mass ejections (CMEs). We select 30 front-side halo CMEs from SOHO LASCO CMEs whose speed is larger than 1000km/s and longitude is less than ${\pm}30^{\circ}$. These are thought to be the most plausible candidate of geoeffective CMEs. We examine the relation between CMEs directional parameters (Earthward direction, eccentricity, ${\Delta}$ distance and central angle parameter) and the minimum value of the Dst index. We have found that the Earthward direction parameter has a good correlation with the Dst index, the eccentricity parameter has a much better correlation with the Dst index. The bo distance and central angle parameter has a poor correlation with the Dst index. It's, however, well correlated with the Dst index in very strong geomagnetic storms. Most of CMEs causing very strong storms (Dst ${\leq}$-200nT) are found to have large Earthward direction parameter $({\geq}0.6)$, small eccentricity, bo distance and central angle parameters $(E{\leq}0.4,\;{\Delta}X\;and\;sin\;{\theta}{\leq}0.2)$. These directional parameters are very important parameters that control the geoeffectiveness of very fast front-side halo CMEs.

• Journal of the Society of Disaster Information
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• v.11 no.4
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• pp.597-606
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• 2015

Until now, u-turn lane installation methods have been studied variously. But, There is no specific standard yet. This study ranges are commercial area in Incheon metropolitan city through field investigation and presents specific design standard for efficient operation of left turn using a field data through calculating relevant permitted u-turn lane length and minimum separation distance from the front intersection to starting point of permitted u-turn lane in urban signalized intersections in commercial area. Relevant permitted u-turn lane length is found to be 32m and minimum separation distances from the front intersection to starting point of permitted u-turn lanes are 72m, 40m, 24m in case of 1 left turn lane, 2 left turn lanes and 3 left turn lanes respectively. By comparing result values and field data, they had a large difference under the similar situations in their lengths. This result is caused of no specific standard about design of u-turn lanes. If results of this study applied to design of u-turn lanes, signalized intersections in urban commercial areas would be operated more safety and efficiently.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.3
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• pp.113-127
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• 2015

Recently, there has been a growing interest in UAS(Unmanned Aerial System), and it is required to develop techniques to effectively detect water body from the recorded images in order to implement flood monitoring using UAS. This study used a UAS with RGB and NIR+RG bands to achieve images, and applied supervised classification method to evaluate the accuracy of water body detection. Firstly, the result for accuracy in water body image classification by RGB images showed high Kappa coefficients of 0.791 and 0.783 for the artificial neural network and minimum distance method respectively, and the maximum likelihood method showed the lowest, 0.561. Moreover, in the evaluation of accuracy in water body image classification by NIR+RG images, the magalanobis and minimum distance method showed high values of 0.869 and 0.830 respectively, and in the artificial neural network method, it was very low as 0.779. Especially, RGB band revealed errors to classify trees or grasslands of Songsan amusement park as water body, but NIR+RG presented noticeable improvement in this matter. Therefore, it was concluded that images with NIR+RG band, compared those with RGB band, are more effective for detection of water body when the mahalanobis and minimum distance method were applied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.88-95
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• 2015

This paper presents the study of the efficient localization algorithm for non-linear least square estimation. Although non-linear least square(NLS) estimation algorithms are more accurate algorithms than linear least square(LLS) estimation, NLS algorithms have more computation loads because of iterations. This study proposed the efficient algorithm which reduced complexity for small accuracy loss in NLS estimation. Simulation results show the accuracy and complexity of the localization system compared to the proposed algorithm and conventional schemes.

• Journal of the Korean Institute of Gas
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• v.16 no.1
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• pp.15-21
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• 2012

An analysis was completed of the hazards distance of hydrogen accidents such as jet release, jet fire, and vapor cloud explosion(VCE) of hydrogen gas, and simplified equations have been proposed to predict the hazard distances to set up safety distance by the gas dispersion, fire, and explosion following hydrogen gas release. For a small release rate of hydrogen gas, such as from a pine-hole, the hazard distance from jet dispersion is longer than that from jet fire. The hazard distance is directly proportional to the pressure raised to a half power and to the diameter of hole and up to several tens meters. For a large release rate, such as from full bore rupture of a pipeline or a large hole of storage vessel, the hazard distance from a large jet fire is longer than that from unconfined vapor cloud explosion. The hazard distance from the fire may be up to several hundred meters. Hydrogen filling station in urban area is difficult to compliance with the safety distance criterion, if the accident scenario of large hydrogen gas release is basis for setting up the safety distance, which is minimum separation distance between the station and building. Therefore, the accident of large hydrogen gas release must be prevented by using safety devices and the safety distance may be set based on the small release rate of hydrogen gas. But if there are any possibility of large release, populated building, such as school, hospital etc, should be separated several hundred meters.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.887-895
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• 1995

Considering that the laser range finder has the excellent resolution with respect to angular and distance measurements, a sophisticated local path planning algorithm is achieved by subgoal and sub-subgoal searching methods. The subgoal searching finds the passable ways between obstacles and selects the optimal pathway in order to reduce the moving distanced from start point to given to given goal. On the other hand, the sub-subgoal searching corrects the path given in subgoal searching in the case of which the mobile robot will collide with obstacles. Also, the effectiveness of the established local path planning and local minimum avoiding algorithm are estimated by computer simulation and experimentation in complex environment.

• 한국IT서비스학회:학술대회논문집
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• 2007.11a
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• pp.673-678
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• 2007

본 연구는 지리학적으로 산재해 있는 다양한 수요지점을 서비스할 수 있는 차량경로모델을 개발한다. 즉 다양한 수요지점을 구역으로 분할하여 각 수요지점의 수요량과 서비스 레벨을 고려하여 최적차량 운송계획 모형을 개발하는 데 있다. 본 연구 방법에서 사용된 접근 방법으로 먼저 단일 출발점에서 각 수요지점의 수요조건을 만족하는 범위 내에서 최소의 운반 거리 및 수요 조건을 만족하도록 각 서비스 지역을 할당하는 Clustering Algorithm을 개발하여 단일 구역별 최적의 이동 경로를 개발하였다. 그리고 각 수요지점별 수요량의 평균과 표준편차를 고려하여 새로운 Saving Algorithm을 기반으로 하여 운송 가능한 차량별 수요지점을 할당하였다. 또한 각 차량경로 구역별 서비스 레벨을 고려한 개선된 알고리즘을 사용하여 차량경로 문제의 근본적인 목적인 이동 거리(비용, 시간)의 최소화와 고객서비스 극대화를 동시에 달성하기 위한 최적 차량 운송 계획 모델을 개발하였다. 마지막으로 수치적 예제를 통해 본 연구에서 사용된 모델들과 기존 모델들과의 비교를 수행하였다.