• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.16 no.1
• /
• pp.193-198
• /
• 2016

For environmental monitoring and risk identification of industrial plants, several monitoring systems using Wireless Sensor Networks (WSNs) have been developed. In this paper, we propose a dynamic duty cycle adjustment mechanism for reduced latency in industrial plants. The proposed method adjusts the duty cycle among predefined risk groups depending on the urgency of sensed data values. To demonstrate its efficacy, we analyze the expected transmission latency model and then discuss the characteristics in detail. We show that the proposed dynamic duty cycle mechanism is a more effective than a periodic mechanism by analyzing the expected latency of them in industrial plants where there are various types of sensory data with different levels of reliability.

• Journal of Korean Society of Transportation
• /
• v.25 no.4
• /
• pp.21-32
• /
• 2007

The households to be surveyed are usually huge number at the level of a city or metropolitan survey, not to mention a nationwide travel survey. Therefore, household travel surveys to figure out true origin-destination (O/D) trip patterns (population O/D) are conducted through a sampling method rather than by surveying all of the population in the system. Therefore, the population O/D pattern can only be estimated by expanding the sampled O/D patterns to the population. It is very difficult to avoid the errors involved in the process of sampling, surveying and expanding O/D data. In order to minimize such errors while estimating the true O/D patterns of the population, the validation and adjustment process should employed by doing a comparison between the expanded sample O/D data and observed link traffic volumes. This study suggests a method of validation and adjustment of the expanded sample O/D data by comparing observed link volumes at several screenlines. The study also suggests a practical technique to modify O/D pairs which are excluded in the screenline validation process by comparing observed traffic volume with the results of traffic assignment analysis. An empirical study was also conducted as an example applying the suggested methods of validation and adjustment with Korea's nationwide O/D data and highway network.

• Journal of Korean Society for Geospatial Information Science
• /
• v.16 no.3
• /
• pp.3-13
• /
• 2008

The coordinate of cadastral control points located over the area of different surveying origins is computed in a single surveying origin by trilateration adjustment of GPS baseline measurements. In every different surveying origins, well-matched control points are selected and mutually coinciding coordinates are computed by free network adjustment. Then, the coordinate of the other control points over the area is computed by joining these points to the adjusted points. In practice, by using 18 points of Gari, 17 points of Gyeyang, and 33 points of Central origin in Incheon, the coordinates of total 68 points in every surveying origin are computed. Between the points of different surveying origins, it is found that there are quantitative differences in azimuth and scale factors and the approximate point coordinate of other surveying origins is calculated by correcting the scale and azimuth.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.7 no.2
• /
• pp.35-43
• /
• 1989

The improvements of highly accurate and dense control networks are major requirements to carry out numerical surveying and a large scale mapping for cadastral renovation. In the most conventional photogrammetric solutions, adjusted control coordinates have been applied to block triangulations. However, this study, imploying real data and those of simulated as well, contributes to a simultaneously combined adjustment. It also contains such photogrammetric as photocoordinates and geodetic observations like distances, angles and hight differences. Its purpose is to introduce the improved results, despite it is not sufficient for the ground network. In addition, through the detection of gross error, more precise observational data can be selected for the better adjustment. All in all, the result of this study can be summarized as follows : First, even if the ground control points are not sufficient nor existed at all, the combination of pbotogrammetric and geodetic observations are improved its accuracy. Secondly, the case #2 is more accurate than that of #3, and the case #7 comes into close to that of #6.

• Journal of Cadastre & Land InformatiX
• /
• v.54 no.1
• /
• pp.103-115
• /
• 2024

Trilateral adjustment can complement the problem of transforming cadastral maps into World Geodetic Coordinate system. First, it is possible to determine adjusted coordinate of common points that match each other over a wide area. Second, calculations that focus on specific points can be performed. Third, a solution that maintains the shape of the regional network can be obtained through constraints. Thus, the point coordinates can be determined appropriately for the survey system. In addition, heterogeneous survey results that span regions with different coordinate origins can be calculated on a single origin coordinate. This improves the efficiency of the workflow in tranforming cadastral maps into World Geodetic Coordinate System.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.3
• /
• pp.1492-1509
• /
• 2017

The wireless sensor network (WSN) is a key technology to support the Internet of things (IoT) paradigm. The efficiency of the MAC protocol in WSN is very important to take scalability with restricted wireless resources. The DESYNC-TDMA has an advantage of simple distributed slot allocation inspired by nature, but there is a critical disadvantage of split slots by firing message. The basic split slot model has less efficiency for continuous packet transmitting because of wasting of the slots less than the packet size. In this paper, we propose a firing offset adjustment scheme to improve the efficiency of slot utilizations, which can manage the slot assigned to each node as a single large block, called the single slot model. The performance analysis models for both the existing and the proposed schemes are also derived. Experimental results show that the proposed method provide better efficiency of slot utilization than the existing schemes without any loss of the nature of the desynchronization.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.6 no.1
• /
• pp.13-24
• /
• 1988

The determination of three-dimensional positions on a circular or cylindrical surface covers a variety of applications. As an example, consider the monitoring of structures, which is an important topic in the broad category of deformation analysis. The use of convergent photography in determination of these positions has the many advantages over survey based procedures. This paper illustrates results from bundle adjustments derived from convergent photography of a cylindrical object, with both metric and non-metric cameras utilized in the test. In addition to standard error comparisons resulting from the error analysis provided by the bundle adjustments, object space coordinates resulting from metric and non-metric camera network geometries will also be compared.

• Journal of Advanced Navigation Technology
• /
• v.21 no.6
• /
• pp.572-578
• /
• 2017

As the demand of high accuracy positioning for dynamic users increases, Network RTK is actively researched for dynamic users. Network RTK is a system which provides precise positioning in the range of about 50 to 70km radius using carrier phase measurements from several reference stations. By configuring multiple clusters, which provide Network RTK corrections independently, as a single system, it could provide precise positioning for a wider area. In this paper, we have studied how to efficiently operate multiple clusters in the Korean Peninsula. We analyzed the computational load according to the configuration of a multi-cluster system and proposed a method of selecting the main reference station and system infrastructure configuration for efficient operation. In order to analyze the effects of each proposed method, 71 clusters were constructed using the reference stations of the National Geographic Information Institute and simulations were conducted. As a result of the simulation, system computation amount was reduced by 66 % and system configuration cost was reduced by 90 %.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.11B
• /
• pp.956-966
• /
• 2004

Nowadays, NGN(Next Generation Network) is evolving into network with packet based QoS.\ulcorner This paper presents the recovery method as a selecting way of more efficient path in MPLS network that reduces the service interruption time. In order to increase the efficiency of usage of recovering resource which is one of major functions of disorder recovering, it opens the state information of each Node both to fault detector and bandwidth broker so that it reduces message transmission time for recovery when functional disorder occurs. in addition, by effective management and adjustment of required bandwidth of entire network depending on the changes of traffic load, it improves the efficiency of bandwidth usage. and in MPLS network supporting priority selection function, it allocates domains depending on the traffic relating to priority order to the entire network so that\ulcorner it efficiently allocates proper resources to the restoring process between the entry and the end for the traffic of high priority and for low priority traffic, it restores path oかy inside disordered domain. by doing this, it reduces resetting time and unnecessary massage transmission.

• Journal of Korea Multimedia Society
• /
• v.9 no.3
• /
• pp.369-376
• /
• 2006

In this paper, we propose an improved fuzzy RBF network which dynamically adjusts the rate of learning by applying the Delta-bar-Delta algorithm in order to improve the learning performance of fuzzy RBF networks. The proposed learning algorithm, which combines the fuzzy C-Means algorithm with the generalized delta learning method, improves its learning performance by dynamically adjusting the rate of learning. The adjustment of the learning rate is achieved by self-generating middle-layered nodes and by applying the Delta-bar-Delta algorithm to the generalized delta learning method for the learning of middle and output layers. To evaluate the learning performance of the proposed RBF network, we used 40 identifiers extracted from a container image as the training data. Our experimental results show that the proposed method consumes less training time and improves the convergence of teaming, compared to the conventional ART2-based RBF network and fuzzy RBF network.