• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.1-9
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• 2009

Bus information system(BIS), as a part of the intelligent transportation system(ITS), is one of the most advanced public transportation systems which provide the real-time bus traffic information for the users waiting the buses at the bus stop. However, correct bus information data, such as the present bus location, the user waiting time, the bus arrival time, etc. are not provided for the bus users because the proper bus arrival time predictive models are not used yet in most of the cities operating the bus information system, including the metropolitan City of Ulsan. Thus, the purpose in this study is to investigate real-time bus traffic characteristic data for identifying the bus operation characteristics on the arterial under the study in the metropolitan City of Ulsan, analyze real-time bus traffic characteristic data on the ID locations of the arterial under the study, construct the optimal unit segment models for the unit segments which are the bus stop, node and travel section using the exponential smoothing, weighted smoothing and Kalman Filter methods, respectively, and finally suggest the optimal integrated model for predicting the real-time bus arrival time at the bus stop of the arterial under the study.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.463-472
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• 2017

Inertial Navigation System Alignment is the process to determine direction cosine matrix which is the transformation matrix between the INS body frame and navigation frame. INS initial position value is necessary to INS attitude calculation, so that user should wait until he get such value to start the INS alignment. To remove the waiting time, we propose an alignment algorithm that immediately starts after the INS power on by using pseudo initial position input and then is completed with attitude error compensation by entering true position later. We analyse effect of INS sensor error on attitude in process of time and verify the performance and usefulness of the close-loop alignment algorithm which corrects attitude error from the change of initial position.

• Journal of KIISE:Databases
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• v.29 no.1
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• pp.15-26
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• 2002

Most work on multimedia storage systems has assumed that client will be serviced using a round-robin strategy. The server services the clients in rounds and each client is allocated a time slice within that round. Furthermore, most such algorithms are evaluated on the basis of a tightly coupled cost function. This is the basis of well-known algorithm such as FCFS, SCAN, SCAN-EDF, etc. In this paper, we describe a scheduling module called Request Unifier(RU) that takes as input, a set of client request, and a set of constraints on the desired performance such as client waiting time or maximum disk bandwidth, and a cost function. It produces as output a Unified Read Request(URR), telling the storage server which data items to read and when these data items to be delivered to the clients. Given a cost function, a URR is optimal if there is no other URR satisfying the constraints with a lower cost. We present three algorithms in this paper that can accomplish this kind of request merging and compare their performance through an experimental evaluation.

• The Journal of the Korea Contents Association
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• v.18 no.3
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• pp.34-40
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• 2018

In this study, the optimal buffer size is calculated for seamless video playback on a mobile device. Buffer means the memory space for multimedia packet which arrives in mobile device for video play such as VOD service. If the buffer size is too large, latency time before video playback can be longer. However, if it is too short, playback service can be paused because of shortage of packets arrived. Hence, the optimal buffer size insures QoS of video playback on mobile devices. We model the process of buffering into a discret-time queueing model. Mean busy period length and mean waiting time of Geo/G/1 queue with N-policy is analyzed. After then, we uses the main performance measures to present numerical examples to decide the optimal buffer size on mobile devices. Our results enhance the user satisfaction by insuring the seamless playback and minimizing the initial delay time in VOD streaming process.

• KIPS Transactions on Software and Data Engineering
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• v.1 no.3
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• pp.149-158
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• 2012

As service-oriented software is considered as one of solutions to fulfill the users' needs in internet service environment, it has been increased the demands of reliable service development by the composition of internet services. However a critical issue in the service development approach is to satisfy the performance requirement as well as the functional correctness for the developing services, because impatient user multiply clicks the request-button of service without a short waiting. This paper proposes a framework to examine the performance of composite service. Our testing framework provides the data of service response time to service developer by measuring the service execution time. We develope an Aspect-based timer service, and weave the service with existing services to measure the execution time. Additionally, we perform some experiments to confirm the usefulness of performance test for composite service. This framework can support to develop a good performance service by substitution of the dragging service with another new service that will be a component of composite service.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.2
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• pp.1-17
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• 2018

The living lab is a user-participatory innovation space where users can solve problems by themselves. Living Lab members are able to participate in all aspects of product development from technology conception. In this study, to prevent pedestrian accidents, auto-image sensing signal system was developed in Jeonju City, using the Living Lab method. In addition, we measured effectiveness of the auto-image sensing signal system with respect to pedestrian waiting time, pedestrian and driver signal violation, and pedestrian jaywalking. It was also compared the measures before installation, after installation and after applying Living Lab method. As a result, all of the three measures of effectiveness appeared to be more effective after Living Lab than after installation. Overall, this study is very significant in that it is the first case where the living lab is applied in transportation.

• Journal of the Korean Society for Library and Information Science
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• v.34 no.4
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• pp.5-26
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• 2000

The purpose of this study was to measure performance of university libraries, especially investigating the components of service quality and their relationship to the customer satisfaction. The result of the study was summarized as follows: First, the factors on satisfaction of library service revealed 12 factors such as access of information, quality of employees, suitable collections, issues related to civil petitions, equipments and facilities, timeliness, operating hours, use of information technology, library user education, reference service, public relation and individual service. Second, the factors of library service on customer satisfaction showed the following primary factors: suitable collections, issues related to civil petitions, access of information, equipments and facilities, timeliness, public relation, reference service, operating hours, and individual service. Third, the components of library service on customwe satisfaction showed the following primary components: availability, the number of books and journals, facilities of air conditioning, public relation, usefulness of retrieval system, waiting time for Internet use, operating hour, speed of repairs, receipt of civil petitions, use of non-book materials.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.730-738
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• 2010

In the development of railroad station area, there are many factors about business management, but the interest of railroad users is an important factor as customer satisfaction. It is necessary to have the quality estimation of railroad service, and important factors of service as customer satisfaction aspects can be supply, reliability, convenience, and safety. In this study, primary factors are deduced in the efficiency aspects of railroad station facilities from analyzing relative importance index using AHP(Analytic Hierarchy Process) methods. The most high rank important factor is railroad station user facilities, and the AHP importance index of passenger facilities and elevator facilities for KORAIL personnel and facility users is index. The third of KORAIL personnel is movement facilities, but facility users index is sanitation. And the low important factors of KORAIL personnel and facility users are shown as the platform in passenger facilities, the rest facilities in waiting room, the escalator in going up and coming down facilities, the escalator in movement facilities, the raised letters block in guide facilities, and the parking lot in subsidiary facilities.

• The KIPS Transactions:PartD
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• v.12D no.1 s.97
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• pp.151-158
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• 2005

In order to use the existing map data base in the mobile phone, the dynamic creation technique of the radio map which will be able to be converted into the raster image and transmitted was proposed. We transferred the client module functions such as the coordinate conversion, data compression and decoding to server, and made driving of JAVA browser in the mobile phone which has the restricted resources possible for the dynamic creation of the radio map. We made the radio electronic map service possible without map data base for the mobile phone use only by performing the general work of the map at the sever. And we guaranteed the client waiting time less then the limit time by performing the filtering work of the map at the server also. After we input the keyword at the user interface for searching the region or facility, and verified the performance of the proposed technique by confirming that the raster electronic map usable at the mobile phone was created dynamically.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1C
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• pp.90-95
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• 2002

Though the FTP(File Transfer Protocol) has been used widely and stable, It has the structural weakness that can't support current file transmissions so that we have to wait the completion of previous file transmission when try to transmit another file. If try to transmit multiple files concurrently using this FTP, It has to forking multiple FTP servers and clients in each user's PC and ISP's host machine it would result in the waist of memory, resource of network and the high workload of system. In order to solving previous problem, in this paper I have designed the new model of FTP which based on multi-thread and created NFTP(Next-Generation FTP)protocol so that may reduce the workload of system and support current file transmission effectively. I have implemented NFTP and also applied to real service, as a result It have provided reliable service by reducing the workload of system and saved the waiting time which would happened.