• Journal of the military operations research society of Korea
• /
• v.26 no.1
• /
• pp.89-99
• /
• 2000

This paper deals with a heuristic algorithm for the vehicle routing-scheduling problem to minimize the total travel distance and the total cost. Because the aim of the Clarke-Wright method, one of famous heuristic methods, is to minimize the total travel distance of vehicles, it cannot consider the cost if the cost and the travel distance is not proportional. In the Clarke-Wright method, the route of each vehicle is found by using the saving matrix which is made by an assumption that the vehicle comes back to the starting point. The problem dealt with in the paper, however, does not need the vehicle to come back because each vehicle has its hoping-start-points and hoping-destination-points. Therefore we need a different saving matrix appropriate to this occasion. We propose a method to find an initial solution by applying network simplex method after transforming the vehicle routing-scheduling problem into the minimum cost problem. Moreover, we propose a method to minimize the total travel distance by using the modified saving matrix which is appropriate to no-return occasion and the method for the case of plural types of vehicles and freights.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2003.11a
• /
• pp.57-60
• /
• 2003

As the business dependency to information systems and the frequency of the large scale disasters increase, implementing the disaster recovery center has been a common practice. However, since there has been little quantitative decision method for the distance between the data center and the disaster recovery center, the distance decision has been commonly made by qualitative guidelines. In this research, the decision method for the optimal distance between the data center and the disaster recovery center is developed, using the cost analysis including the operation cost and the expected disaster cost. An illustrative numerical example is provided.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.5 no.7
• /
• pp.9-15
• /
• 1982

The rectilinear-distance location problem combines the property of being a very appropriate distance measure for a large number of location problems and the property of being very simple to treat analytically. An obvious question to be asked at the optimal point which is obtained by the rectilinear distance method is, "what if the point is not available as a location site\ulcorner." The point may, for example, be inaccessible or may coincide with the location of another structure, a river, or a municipal park. In this case, one approach that may be employed is to construct contour lines (also called iso-cost or level curves) of the cost function. Contour lines provide considerable insight into the shape of the surface of the total cost function as well as a useful means of evaluating alternative locations for the new facility. But, when there is an obstacle which divides the application area into two. The optimal location(which is acquired by the rectilinear distance method) is not coincide with the minimal cost point and the contour line is occasionally of no use, this paper shows the method of finding a way to decide an optimal point of single facility location in this case.this case.

• Journal of Korea Spatial Information System Society
• /
• v.11 no.4
• /
• pp.85-88
• /
• 2009

In multimedia database systems, the nearest neighbor Query occurs frequently and requires the processing cost higher than other spatial Queries do. It needs the measurement of search distance that the number of searched nodes and the computation time in an index can be minimized for optimizing the cost of processing the nearest neighbor query. The circular location property of objects is considered to accurately select the nodes which will be searched in the nearest neighbor query. In this paper, we propose the processing method of nearest neighbor queries be considered a circular location property of object where the search space consists of a circular domain and show its characteristics. The proposed method uses the circular minimum distance and the circular optimal distance, the search measurement for optimizing the processing cost of nearest neighbor queries.

• Journal of Environmental Impact Assessment
• /
• v.17 no.2
• /
• pp.133-141
• /
• 2008

The loss, alteration, and fragmentation of habitat have led to a reduction of biodiversity. The growing awareness of the negative effects of habitat fragmentation on natural systems has resulted in conservation strategy that is concerned with not only population and habitat level but also ecosystem and landscape level. Especially, ecological network to link core areas or major habitat patches is one of the most important issues. Recently, landscape connectivity is increasingly used in decision making for fragmented landscape management in order to conserve the biodiversity in the regional scale. The objective of this study was to find potential forest as a ecological corridor in Go-yang city, Gyung-gi province using cost-distance modelling method that can measure connectivity based on animal movement. 'Least cost-distance' modelling based on functional connectivity can be useful to establish ecological network and biodiversity conservation plan. This method calculates the distance modified with the cost to move between habitat patches based on detailed geographical information on the landscape as well as behavioural aspects of the animal movement. The least cost-distance models are based on two biologically assumptions: (1) dispersers have complete knowledge of their surroundings, and (2) they do select the least cost route from this information. As a result of this study, we can find wildlife moving route for biodiversity conservation. The result is very useful for long-term aspect of biodiversity conservation plan in regional scale, because this is reflection of geographical information and behavioural aspects of the animal movement.

• Journal of Electrical Engineering and Technology
• /
• v.6 no.3
• /
• pp.302-310
• /
• 2011

Congestion management is one of the most challenging tasks of a system operator to ensure the operation of transmission system within operating limits. In this paper, cluster/zone method and relative electrical distance (RED) method for congestion management are compared based on the considered parameters. In the cluster/zone method, rescheduling of generation is based on user impact on congestion through the use of transmission congestion distribution factors. In the RED method, the desired proportions of generations for the desired overload relieving are obtained. Even after generation rescheduling, if congestion exists, load curtailment option is also introduced. Rescheduling cost, system cost, losses, and voltage stability parameter are also calculated and compared for the above two methods of congestion management. The results are illustrated on sample 6-bus, IEEE 30-bus, and Indian utility 69-bus systems.

• Current Optics and Photonics
• /
• v.5 no.3
• /
• pp.298-305
• /
• 2021

Modern distance sensing methods employ various measurement principles, including triangulation, time-of-flight, confocal, interferometric and frequency comb. Among them, the triangulation method, with a laser light source and an image sensor, is widely used in low-cost applications. We developed an omnidirectional two-dimensional (2D) distance sensor based on the triangulation principle for indoor floor mapping applications. The sensor has a range of 150-1500 mm with a relative resolution better than 4% over the range and 1% at 1 meter distance. It rotationally scans a compact one-dimensional (1D) distance sensor, composed of a near infrared (NIR) laser diode, a folding mirror, an imaging lens, and an image detector. We designed the sensor layout and configuration to satisfy the required measurement range and resolution, selecting easily available components in a special effort to reduce cost. We built a prototype and tested it with seven representative indoor wall specimens (white wallpaper, gray wallpaper, black wallpaper, furniture wood, black leather, brown leather, and white plastic) in a typical indoor illuminated condition, 200 lux, on a floor under ceiling mounted fluorescent lamps. We confirmed the proposed sensor provided reliable distance reading of all the specimens over the required measurement range (150-1500 mm) with a measurement resolution of 4% overall and 1% at 1 meter, regardless of illumination conditions.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.130.4-130
• /
• 2001

In this paper, a measurement system of moving distance is developed. The error compensation method is also proposed using the characteristics of walking motion. As personal navigation systems and multimedia systems are emerging into the commericial market, men´s moving distance is considered as one of the important information. GPS offers the information easily but GPS can be used only when the satellites are visible. INS can calculate the moving distance anywhere but error is increased with time due to the sensor bias. In this paper, to detect the human walking distance a measurement system of moving distance only using low-cost accelerometer is developed. The sensor bias is estimated and compensated using the walking motion characteristics. The performanced of the proposed system is verified by experiment.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.1
• /
• pp.32-41
• /
• 1999

In spatial database system, the nearest neighbor query occurs frequently and requires the processing cost higher than other spatial queries do. The number of nodes to be searched in the index can be minimized for optimizing the cost of processing the nearest neighbor query. The optimal search distance is pr9posed for the measurement of a search distance to accurately select the nodes which will be searched in the nearest neighbor query. In this paper, we prove properties of the optimal search distance in N-dimensional. We show through experiments that the performance of query processing of our method is superior to other method using maximum search distance.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.5
• /
• pp.422-428
• /
• 2013

Recently, many unmanned aerial vehicle (UAV) studies have focused on small UAVs, because they are cost effective and suitable in dangerous indoor environments where human entry is limited. Map building through distance measurement is a key technology for the autonomous flight of small UAVs. In many researches for unmanned systems, distance could be measured by using laser range finders or stereo vision sensors. Even though a laser range finder provides accurate distance measurements, it has a disadvantage of high cost. Calculating the distance using a stereo vision sensor is straightforward. However, the sensor is large and heavy, which is not suitable for small UAVs with limited payload. This paper suggests a low-cost distance measurement system using a laser pointer and a monocular vision sensor. A method to measure distance using the suggested system is explained and some experiments on map building are conducted with these distance measurements. The experimental results are compared to the actual data and the reliability of the suggested system is verified.