• Journal of Korean Society for Geospatial Information Science
• /
• v.22 no.3
• /
• pp.145-154
• /
• 2014

The road network becomes more complex and extensive. Therefore, the inconveniences are caused in accordance with the time delay of the restoration of damaged roads, demands for excessive costs on information collection, and limitations on acquisition of damage information of the roads. Recently, road centric spatial information is gathered using mobile multi sensor system for road inventory. But expensive MMS(Mobile Mapping System) equipments require high maintenance costs from beginning and takes a lot of time in the data processing. So research is needed for continuous maintenance by collecting and displaying the damaged information on a digital map using low cost mobile camera system. In this research we aim to develop the techniques for mosaic with a regular ground sample distance using successive image from oblique camera on a vehicle. For doing this, mosaic image is generated by estimating the homography of high resolution oblique image, and the ground sample distance and appropriate overlap are analyzed using high resolution aerial oblique images which contain resolution target. Based on this we have proposed the appropriate overlap and exposure interval for mobile road inventory system.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.6
• /
• pp.131-142
• /
• 2011

In this paper, we propose a new multipath routing protocol and compare it with other multipath routing protocols in mobile ad hoc network (MANET) environments. The new multipath routing establishes the main route using a mechanism based on Ad Hoc On-demand Distance Vector(AODV), after which data transmission starts immediately. The backup route search process takes place while data are transmitted, to reduce the transmission delay. The protocol can also operate in a hybrid node-disjoint/link-disjoint mode, where the protocol finds the node-disjoint backup route first; if the node-disjoint does not exist, the protocol discovers the link-disjoint backup route from the main route. When either of the main route or the backup route is broken, data are transmitted continuously through the other route and the broken route is recovered by the route maintenance process. The results of simulations, based on the Qualnet simulator, show that the proposed multipath routing protocol increases the packet transmission success rate and reduces end-to-end delays, when compared with AODV and AOMDV protocols.

• Journal of the Korea Society of Computer and Information
• /
• v.12 no.3
• /
• pp.165-175
• /
• 2007

The mobile agent executes a given task by which the agent code moves to the server directly. Therefore, node migration method becomes an important factor which impact on the whole performance of distributed system. In this paper, we propose an adaptive migration path technique of mobile agent using the metadata of naming agent. In this proposed technique, node selection for migration depends on the content of referenced metadata, and the reliability of migrated information is determined by the metadata updating method and cooperative operations of individual agents in multi-agents system. For these, we design the metadata using by the number of hit documents, hit ratio, node processing time and network delay time, and describe the methods for creating, using and updating metadata for which determine the adaptive node migration path of mobile agent according to the cooperation of individual agents and number of hit documents using by designed metadata. And results of evaluated performance for proposed adaptive migration path technique through the proper experiment and analysis gain rate of high effective information earning, because of high hit ratio(72%) about of fathered documents by case of applying metadata move to the 13 nodes. But, in case of non-applying metadata is hit ratio(46%) of gathered documents and rate of effective information earning about of 26 nodes is 36.8%.

• Journal of Korean Society for Atmospheric Environment
• /
• v.21 no.4
• /
• pp.401-411
• /
• 2005

This study was conducted to develop a method to be able to estimate the vehicular emissions according to spatial scales-Seoul province, 25 counties and hundreds of grids $(1km{\times}1km)$. First, the emissions at each spatial scale was calculated by using the road network and the travel volume and speed of each link modeled by travel demand model (TDM). Second, the emission at each spatial scale was calculated on the basis of average speeds estimated by using three kinds of averaging method. These are called the provincial, volume-delay function (VDF) and zonal method, respectively. Third, three kinds of emissions and those by TDM are compared each other at three spatial scales. In Seoul (provincial scale), three kinds of emissions are less than those by TDM, but the differences of TDM from three speed averaging methods (SAMs) are small. The relative ratios of three SAMs to TDM are $88\~90\%\;in\;CO,\;99\~100\%\;in\;NOx,\;84\~85\%$ in VOCs. At county scale, NOx among three pollutants showed the highest correlation between TDM and three SAMs and the zonal method among three SAMs was proven to be the highest correlation with TDM. NOx showed the coefficients $(R^2)$ greater than 0.9 in all three SAMs but CO and VOC showed the coefficients $(R^2)$ greater than 0.9 in only zonal method. Slopes of co..elations of all pollutants showed the values close to '1' in zonal method. In the other two SAMs, slopes of NOx showed the values close to '1', but those of CO and VOC showed the values less than 0.85. At grid scale, correlations between TDM and three SAMs were not high. CO showed $0.68\~0.77\;in\;R^2s\;and\;58\~0.68$ in slopes. NOx showed $0.90\~0.94\;in\;R^2s\;and\;0.86\~0.94$ in slopes. VOC showed $0.56\~0.70\;in\;R^2s\;and\;0.48\~0.57$ in slopes. There are not high correlations between TDM and three SAMs in grid scale. This study showed that there is the most suitable method for calculating the average travel speed at each spatial scale and it is thought that the zonal method is more suitable than the VDF or provincial method.

• Journal of Convergence for Information Technology
• /
• v.10 no.2
• /
• pp.39-48
• /
• 2020

Many studies have been conducted to analyze factors that affect customer satisfaction, and service quality improvement in the parcel delivery industry. Most of these studies have a limited number of respondents using methods such as surveys and interviews. Therefore, this study aims to supplement the shortcomings of previous studies, by searching and analyzing the common major topics related to the complaints pointed out by consumers and suppliers in the parcel delivery service with cases of consumer counseling, and articles that reflect the complaints of workers in the industry. In addition, by analyzing the trend of these topics, we attempted to discover new topics and suggest implications. In conclusion, topics such as delay/lost/wrong deliveries as well as the fierce competition in the parcel delivery industry, turned out to be central aspects. As a result of the topic trend analysis, talks with international couriers have recently increased, and many conflicts related to apartment parcel delivery have been dealt with. The topics presented in this study are mainly focused on the contents of previous studies, but we expect that new and valuable topics can be derived by adding other data and analysis methods, such as internal counseling and academic literature.

• KIEE International Transaction on Systems and Control
• /
• v.2D no.2
• /
• pp.78-91
• /
• 2002

In the thermal power plant, there are six manipulated variables: main steam flow, feedwater flow, fuel flow, air flow, spray flow, and gas recirculation flow. There are five controlled variables: generator output, main steam pressure, main steam temperature, exhaust gas density, and reheater steam temperature. Therefore, the thermal power plant control system is a multinput and output system. In the control system, the main steam temperature is typically regulated by the fuel flow rate and the spray flow rate, and the reheater steam temperature is regulated by the gas recirculation flow rate. However, strict control of the steam temperature must be maintained to avoid thermal stress. Maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature versus changes in fuel flow rate, difficulty of control of the main steam temperature control and the reheater steam temperature control system owing to the dynamic response characteristics of changes in steam temperature and the reheater steam temperature, and the fluctuation of inner fluid water and steam flow rates during the load-following operation. Up to the present time, the Proportional-Integral-Derivative Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on the characteristic comparison of the PID controller and the modified 2-DOF PID Controller (Two-Degrees-Freedom Proportional-Integral-Derivative) on the DCS (Distributed Control System). The method is to design an optimal controller that can be operated on the thermal generating plant in Seoul, Korea. The modified 2-DOF PID controller is designed to enable parameters to fit into the thermal plant during disturbances. To attain an optimal control method, transfer function and operating data from start-up, running, and stop procedures of the thermal plant have been acquired. Through this research, the stable range of a 2-DOF parameter for only this system could be found for the start-up procedure and this parameter could be used for the tuning problem. Also, this paper addressed whether an intelligent tuning method based on immune network algorithms can be used effectively in tuning these controllers.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.7
• /
• pp.18-25
• /
• 2014

To increase wireless capacity, the concurrent use of multiple wireless interfaces on different frequency bands, called aggregation, can be considered. In this paper, we focus on aggregation of multiple Wi-Fi interfaces with packet-level traffic spreading between the interfaces. Two aggregation schemes, link bonding and multipath TCP (MPTCP), are tested and compared in a dualband Wi-Fi radio system with their Linux implementation. Various test conditions such as traffic types, network delay, locations, interface failures and configuration parameters are considered. Experimental results show that aggregation increases throughput performance significantly over the use of a single interface. Link bonding achieves lower throughput than MPTCP due to duplicate TCP acknowledgements (ACKs) resulting from packet reordering and filtering such duplicate ACKs out is considered as a possible solution. However, link bonding is fast responsive to links' status changes such as a link failure. It is shown that different combinations of interface weights for packet spread in link bonding result in different throughput performance, envisioning a spatio-temporal adaptation of the weights. We also develop a mathematical model of power consumption and compare the power efficiency of the schemes applying different power consumption profiles.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.16 no.6
• /
• pp.141-155
• /
• 2017

As the use of SNS becomes more active, many people are posting their thoughts about specific events in their SNS in the form of text. As a result, SNS is used in various fields such as finance and distribution to conduct service satisfaction surveys and consumer monitoring. However, in the transportation area, there are not enough cases to utilize unstructured data analysis such as emotional analysis. In this study, we developed an emotional analysis methodology that can be used in transportation by using highway VOC data, which is atypical data collected by Korea Expressway Corporation. The developed methodology consists of morpheme analysis, emotional dictionary construction, and emotional discrimination of the collected unstructured data. The developed methodology was verified using highway related tweet data. As a result of the analysis, it can be guessed that many information and information about the construction and the accident were related to the highway during the analysis period. Also, it seems that users complain about the delay caused by construction and accident.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.41 no.7
• /
• pp.31-40
• /
• 2004

In this paper, we analyze mathematically the performance of the gated service scheduling in the Interleaved Polling with Adaptive Cycle Time(IPACT) was proposed to control upstream traffic for Gigabit Ethernet-PONs. In the analysis, we model EPON MAC protocol as a polling system and use mean value analysis. We divide arrival rate λ into three regions and analyze each region accordingly In the first region in which λ value is very small, there are very few ONUs' data to be transmitted. In the second region in which λ has reasonably large value, ONUs have enough data for continuous transmission. In the third region, ONUs' buffers are always saturated with data since λ value is very large. We obtain average packet delay, average Queue size, average cycle time of the gated service. We compare analysis results with simulation to verify the accuracy of the mathematical analysis. Simulation requires much time and effort to evaluate the performance of EPONs. On the other hand, mathematical analysis can be widely used in the design of EPON systems because system designers can obtain various performance results rapidly. We can design appropriate EPON systems for varioustraffic property by adjusting control parameters.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.11A
• /
• pp.1908-1924
• /
• 2001

Interoperability and inter-working in the various network and media environment with different technology background is very important to enlarge the opportunity of service access and to increase the competitive power of service. The ITU-T and advanced counties are planning ahead for provision of GII enabling user to access advanced global communication services supporting multimedia communication applications, embracing all modes of information. In this paper, we especially forced the heterogeneity of end user applications for multimedia networking. The heterogeneity has several technical aspects, like different medium access methods, heterogeneous coding algorithms for audio-visual data and so on. Among these elements, we have been itemized bit rate shaping algorithm on the compressed moving video. Previous manipulations of video has been done on the uncompressed signal domain. That is, compressed video should be converted to linear PCM signal. To do such a procedures, we should decode, manipulate and then encode the video to compressed signal once again. The traditional approach for processing the video signa1 has several critical weak points, requiring complexity to implement, degradation of image quality and large processing delay. The bit rate shaping algorithm proposed in this paper process the manipulation of moving video on the completely compressed domain to cope with above deficit. With this algorithms. we could realized efficient video bit rate shaping and the result of software simulation shows that this method has significant advantage than that of pixel oriented algorithms.