• Journal of KIISE:Information Networking
• /
• v.33 no.1
• /
• pp.103-112
• /
• 2006

Priority-based network service has been widely adopted for the Internet traffic management in the context of IETF differentiated services, and computing optimal prices for such priority-based service is the key topic in many pricing literature. While the equilibrium analysis has been commonly used to this end, many have criticized the validity of the underlying assumption of equilibrium analysis that user utility functions are precisely known. In this paper, we propose a solution for bridging the gap between the existing theoretical work on optimal pricing and the unavailability of precise user utility information in real networks. In the proposed method, the service provider obtains more and more accurate estimates of user utility functions from the initial imprecise knowledge by iteratively changing the price of service levels and observing the users' decisions under the changed price. Our contribution is two-fold. First, we have developed a general principle for estimating the user utility functions. Second, we have developed a novel method for setting the prices that can optimize the extraction of the knowledge about user utility functions. The extensive simulation results demonstrate the effectiveness of our method.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.11
• /
• pp.5392-5418
• /
• 2017

The primary aim of this paper is to propose a non-linear regression based technique for mapping different network Quality of Service (QoS) factors to an integrated end-user Quality of Experience (QoE) or Mean Opinion Score (MOS) value for an online video streaming service on a mobile phone. We use six network QoS factors for finding out the user QoE. The contribution of this paper is threefold. First, we investigate the impact of the network QoS factors on the perceived video quality. Next, we perform an individual mapping of the significant network QoS parameters obtained in stage 1 to the user QoE based upon a non-linear regression method. The optimal QoS to QoE mapping function is chosen based upon a decision variable. In the final stage, we evaluate the integrated QoE of the system by taking the combined effect of all the QoS factors considered. Extensive subjective tests comprising of over 50 people across a wide variety of video contents encoded with H.265/HEVC and VP9 codec have been conducted in order to gather the actual MOS data for the purpose of QoS to QoE mapping. Our proposed hybrid model has been validated against unseen data and reveals good prediction accuracy.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.44 no.6
• /
• pp.124-136
• /
• 2002

A freshwater lake water quality management system(FLAQUM) was developed to help regional manager for the water quality of a rural basin. The integrated user interface system FLAQUM written in Visual Basic, includes three subsystems such as a database management system, basin pollutant loads simulation model using SWMM model and freshwater lake water quality simulation model using WASP5 model. Pollutant load simulation model was applied to simulate the discharge and pollutant loading from the watershed, and freshwater lake water quality model was applied to analyze the changes in water quality with respect to watershed pollutant loads, and this model could be used in planning to control watershed pollutant source for water quality management. Database management system was constructed fur all input and output data processing, and it can be used to analyze statistical characteristics using constructed data. Results are displayed both graph and text for convenience of user. The results of FLAQUM application to Boryeong freshwater lake showed that the lake was in eutrophic condition. The major contribution of pollution comes from tributary No.1 and No.4, which have a large number of livestock farms. Therefore, water quality management must be focused on appropriate management of the livestock farming in the two breanchs.

• Journal of Information Technology Applications and Management
• /
• v.11 no.4
• /
• pp.61-85
• /
• 2004

It is tried that evaluation areas and items of information system in public sector are derived ration-ally and its weight value call be applied differently to type of information system to enhance validity and objectiveness of measurement in evaluating IS in this research. To obtain the goal of this research, firstly, five sectors - system sector, user sector, organization and management sector, the degree of strategic contribution to IS, and the degree of optimizing re-source in IS - are categorized based on broadly reviewing previous theoretical and practical research. Secondly, IS type in public sector is divided into internal operation one and customer oriented one that is object of the IS, and divided into application oriented and IT infrastructure oriented which are influence by IS. Thirdly, evaluation areas and its items are measured by 5 point scales (Likert summated scales) in addition to analysis of validity and reliability to improve objectiveness of establishing evaluation areas and its items. Fourthly, the weight values in the evaluation areas and its items are derived by using analytic hierarchy process. According to the results of analysis of weight value through AHP, it were found to be 30.4% to organization and management sector. 25.5% to degree of strategic contribution, 21.0% to user sector, 13.5% to degree of optimization of resource management, and 9.6% to system sector. and. different weight values each of the four IS type are proposed which establishing in this research. The main implications of this study is that the criteria by which IS in public sector can be categorized 4 ones is suggested and The weighted evaluation for four types of IS based on the AHP analysis enables proposing an objective evaluation method of IS in public sector for considering individual IS characterics.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.30 no.1
• /
• pp.29-43
• /
• 2002

The purpose of this paper is to examine atmospherical factors affecting user's satisfaction in natural park to answer the research question: what are the effects of atmosphere on user's satisfaction in natural parks(NP). After reviewing the literature, mechanism of NP, and use elements in NP, We constructed the conceptual framework and have formulated the hypothesis of this research. We had obtained data through a questionnaire, which surveyed 508 visitors at 6 of the 73 NP in Korea in 2001, based on stratified sampling method. We have analyzed the data using descriptive statistical methods, the mean difference test, Pearson's correlation analysis, and the multiple linear regression method. We found that 1) the five atmospheric variables, j.e., number of users(NOU), crowding, damage to park resources(DPR), and maintenance of park resources and facilities(MPRF), encounter level(EL) affecting user's satisfaction, have tuned out to be statistically significant at a five percent level. The direction of the relationship between user's satisfaction and MPRF, NOU, EL is the same as that of the dependent variable and the opposite of crowding, and BPR, 2) in bivariate analysis, the positive relationships between user's satisfaction and park resources, MPRF are fairly high and statistically significant. The higher the value of DPR, and crowing, the lower the degree of user's satisfaction, 3) in multivariate analysis, such variables as NOU, crowding, DPR, EL, and MPRF affecting user's satisfaction have been statistically significant at five percent level, and 4) the relative contribution of MPRF, park resources, park facilities, NOU, crowding, DPR, and size of activity space on user's satisfaction have been determined to have respectively 6.00, 4.78, 2.53, 1.83, 1.64, 1.59 and 2.03 times more important than that of EL. Among the atmospheric variables, MPRF is the most important at 1.26 times higher than that of park resources. The research results suggest that the development of devices for the increase in user's satisfaction and user management program based on the knowledge we have found, be recommended in the planning and development process of natural park. The approach adopted by this research is valid and useful for evaluation criteria of NP. It is recommended that more empirical studies by activity types, activity spaces, and seasons on atmospheric elements affecting user's satisfaction be performed in the future.

• Journal of Digital Convergence
• /
• v.12 no.1
• /
• pp.127-139
• /
• 2014

The purpose of this research is to present the major factors which determine dominant design of Smartphone OS and to verify a logical causal relationship with them and user satisfaction. To achieve this goal, OS compatibility, OS enhancement, Installed base, and network effect were presented as determinants of Smartphone OS which serves as the basis for determining dominant design and their logical causal relationship with user satisfaction was empirically analyzed. The results of the research showed that OS compatibility and OS enhancements had a positive effect on the expansion of user base. Of the two factors, OS enhancement showed that it does not only expand the user base but also acts as the cause for the fortification of the network effect. Furthermore, it was shown that OS enhancement had a direct positive effect on user satisfaction. The findings of this research are significant in its academic contribution as well as its potential for practical application by presenting the logical causal relationship in the process of determining OS dominant design an area which was previously untouched by empirical testing.

• The Journal of Korean Association of Computer Education
• /
• v.5 no.3
• /
• pp.45-58
• /
• 2002

In this paper, we propose the new approach with which user is able to retrieve the massive volume of learning contents in the multimedia learning system. In order to secure the compatibility of learning contents. we apply the SMIL on the basis of XML, so that the integration and the synchronization of multimedia components can be available to realize in the mode of standardization. We also implement the multimedia learning contents represented by the RDF on the IEEE LOM. We present the two step-retrieval method to get precise results. In the first step, user can find with high speed and ease whatever contents user wants to take a look through metadata in the system. The second step is followed that by using the time information of SMIL, user can retrieve the interest synchronous parts in the result of the first step. This innovative retrieval approach applied in the multimedia learning system is highly expected to make a meaningful contribution to implement the principles of self-directed learning in the learning environments, where user can use and revise the retrieval results for their own learning purpose and make further the active knowledge-reconstruction.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38A no.12
• /
• pp.1125-1134
• /
• 2013

Small cells such as pico or femto cells are promising as a solution to cope with higher traffic explosion and the large number of users. However, the users within small cells are likely to suffer severe inter-cell interference (ICI) from neighboring base stations (BSs). To tackle this, several papers suggest BS transmit power on/off control algorithms which increase edge user throughput. However, these algorithms require centralized coordinator and have high computational complexity. This paper makes a contribution towards presenting fully distributed and low complex joint BS on/off control and user scheduling algorithm (FDA) by selecting on/off pattern of BSs. Throughput the extensive simulations, we verify the performance of our algorithm as follows: (i) Our FDA provides better throughput performance of cell edge users by 170% than the algorithm without the ICI management. (ii) Our FDA catches up with the performance of optimal algorithm by 88-96% in geometric average throughput and sufficiently small gap in edge user throughput.

• Journal of Korea Game Society
• /
• v.15 no.3
• /
• pp.7-18
• /
• 2015

This research examined the effects of user experience in driving simulation game between using general monitor and 3D virtual reality device, Oculus Rift DK2. We compared the difference of user experience such as presence, flow and arousal by gaming environment. We also tested the effects of virtual reality on driving attitude, emotional pleasure and satisfaction. 100 beginner drivers with a driver's license participated in the experiment of two modes of gaming environment. As a result, all the three user experiences were proved to be significantly higher in VR game play than general monitor game. Also driving attitude, emotional pleasure and satisfaction showed a significant difference in virtual reality. This study makes a theoretical and practical contribution to the application of the next virtual reality game with a special function.

• Journal of the Korea Convergence Society
• /
• v.9 no.11
• /
• pp.237-244
• /
• 2018

This paper deals with the viewer's recognition of diversity on digital media services. For this reason, the researcher focused on the IPTV user, how the perception of the diversity of the digital media service affected the user's satisfaction. The results are as follows. First, digital media service user recognized that supply side diversity of media channel and VOD affect recognition of accessibility (easy of use) and perceived playfulness. Second user recognized that variety of performers and actors affect recognition of accessibility and perceived playfulness. Moreover, it was found that recognition of accessibility, actor's diversity, perceived playfulness affect use's recognition for media player's contribution of diversity, and media satisfaction. As in this paper, the researcher expects that this kind of methodology for confirming of user's recognition of diversity will contribute to preparing a future media policy.