• International Journal of Railway
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• v.2 no.3
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• pp.118-123
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• 2009

Railway track alignment Standards set a minimum lenght value for straight and circular alignments (art. 5.2.9.), in order to ensure passenger ride comfort in railway vehicles of which dynamic oscillations will thus have to be limited. The transitions between alignments can cause abrupt changes (usually called discontinuities or singular points of the alignment) of curvature, of rate of change of curvature or of rate of change of cant. A passenger is likely to experience effects due to the excitation of the elastic suspension of the vehicle which generates oscillations that are damped as the vehicle moves away from the singularity. The amplitude of these oscillations should be adequately attenuated by the damping of the suspension system within the interval between two successive singular points, especially to avoid resonances. Therefore minimum lengths between two successive singular points are stated in alignment standards. Nevertheless, these nonnative values can be overly conservative in some cases. As an alternative, track alignment designers could try to assess how much the excitation has been attenuated between two successive singular points and thus assess at which point a new singularity may be present without affecting ride comfort. Although such assessment can be made with commercial SW packages which simulate the dynamic behavior of a vehicle considered as a set of rigid bodies interconnected with elastic elements simulating the suspension systems (such as SIMPACK, ADAMS or VAMPIRE), a simplified and user-friendly computation method (based upon the analytical solution of differential equations governing the phenomenon) is made available in this paper to track design engineers, not always used to working with full dynamic models.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.12
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• pp.1093-1105
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• 2012

We propose an interference space reuse (ISR) algorithm for the MU-MIMO design in 3-cell downlink interference channels. Also, we provide a strategy for the adoption of the ISR scheme in the cellular network. In the multicell interference channels, the cell edge users may undergo severe interferences and their signals should be protected from the interferers for reliable transmissions. However, the intra cell users do not only experience small interferences but also they require small transmission power for stable communication. We provide a vector design algorithm based on ISR, where intra cell users are served through reusing the cell edge users' interference space. The performance enhancement reaches 20% compared to the fractional frequency reuse (FFR) scheme combined with IA through the scheduling between the cell edge users and the intra cell users. Also, it can be used to enhance the cell edge throughput when the quality of service (QoS) requirements of the intra cell users are fixed.

• Journal of the Korea Convergence Society
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• v.13 no.4
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• pp.643-651
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• 2022

The mobile augmented reality(MAR) market is rapidly growing with following the sudden rise of the metaverse. However, research on improving user experience in mobile augmented reality environment is lacking. This study aims to develop the usability principles of an AR-based smartphone app. The research conducts following methods. 1)The characteristics of MAR were understood to identify usability elements of AR apps. 2)Usability principles were collected through analysis of case studies on the usability of AR and the 14 usability principles were developed through in-depth interviews with experts for the purpose of chunking. 3)To verify the 14 developed usability principles, evaluation items were composed based on the usability principles and usability evaluation survey was conducted. Consequently, significant differences were found in immersivity, presence, efficiency, satisfaction, playfulness and It was verified that the developed usability principle is useful in developing AR based smartphone apps. This study is meaningful in that it conducted the basic research of mobile AR usability principles

• Journal of Internet of Things and Convergence
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• v.8 no.2
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• pp.49-54
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• 2022

Immersive contents is content that provides a realistic experience by maximizing the user's five senses, and includes virtual reality, augmented reality, and mixed reality. In order to provide a sense of reality to users in immersive content, it is necessary to provide realistic visual images, hearing, and touch. However, due to the rapid change in the environment for developing immersive content, experts in training human resources are having difficulties in designing the curriculum. In this study, we propose a series of educational courses that use drones to acquire and process real-world measurement data and apply the derived data to VR, AR, and MR to help experts in training immersive content develop talent. The design of training process composes through demand survey and analysis of companies, students, and local communities. This study can be a useful resource for education experts who want to train immersive contents manpower.

• Journal of the Korea Convergence Society
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• v.13 no.1
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• pp.167-178
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• 2022

This study attempted to confirm the effect of the user's characteristics on perceived ease of use, perceived usefulness, willingness to pay, flow and addiction to OTT service platform iQIYI users. Researchers believe that as the number of OTT service users who are willing to pay increases, research on the influencing factors and the cause of addiction is needed. As a result of the study, first, it was found that perceived usefulness affects willingness to pay, second, use intention and willingness to pay affect flow, and third, willingness to pay and flow affect addiction. This study considered that it has theoretical and practical value in that the route to flow and addiction of OTT service users was set and tested with intention to use and pay. Researchers hope that the study will expand in terms of willingness to pay and use experience of OTT services in the future.

• Journal of The Korean Association For Science Education
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• v.35 no.3
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• pp.443-453
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• 2015

In this study, we suggested the design thinking process that was possible to be introduced in science education and also examined the validity of the process in terms of group creativity. To do this, the design thinking process applicable to science education was selected from a variety of design thinking processes developed abroad, and then the process was modified and supplemented. We created the education program based on the developed design thinking process and applied it to high school students. The results revealed that we could offer the design thinking process through the five stages: 'understanding knowledge', 'empathy', 'sharing perspective', 'generating idea', and 'prototype'. With the results of the application of the program, we could confirm the relationship building and information seeking attributes in the understanding knowledge stage and the user-orientation, relationship building, and interpersonal understanding attributes in the empathy stage. We could also find the organization of the team attribute in the sharing perspective stage and the analytical strategic thinking attributes in the generating idea stage. Finally, the communication and analytical strategic thinking attributes in the prototype stage were confirmed. All of the key attributes of the group creativity found from skilled professionals were not confirmed from the students. However, we could ascertain the possibilities that the students should experience the process of group creativity and learn the relevant values through the developed design thinking process.

• Journal of the HCI Society of Korea
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• v.12 no.3
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• pp.25-33
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• 2017

Current video service market doesn't satisfy the users' needs who want to find new and interesting contents despite the vast amount of contents. Now it is continuously necessary to Study on technology and using experience is continuously required in online video service area to stimulate the watching motivation efficiently with such as recommendation or promotion. One of efficient ways of increasing the using motivation is to give the users pleasure when they use the services. This study focused on 'unexpected funny finding' as a strategy of providing pleasure of using. It was believed that it could increase the pleasure of using the service, if serendipity, which means unexpected pleasure, accidental finding such as finding a beautiful $caf{\acute{e}}$ or meeting a friend at a certain place unexpectedly, is applied. This study defines the serendipity as 'contents that give unexpected pleasure' at the online video environment. First it theoretically extracted the various characteristics of serendipity through reading many books. Next it verified the other concept of serendipity through the diary of users' survey to additionally extract the characteristics of serendipity at video environment that are hard to find in books. It formed estimation items for the characteristics of the extracted serendipity and tested them in youtube to confirm the characteristics of serendipity being found in video service and observe potential factors that make it. As a result if verified and confirmed four factors that cause serendipity at video environment. This study could be used as basic data to understand the concept of serendipity. It has an academic meaning in the point that it could be a useful reference for the future study that analyzes the role or effect of serendipity at IT area including online video service.

• Journal of KIISE:Software and Applications
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• v.33 no.5
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• pp.508-524
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• 2006

We present our experience of combining, in a realistic setting, a static analyzer with a statistical analysis. This combination is in order to reduce the inevitable false alarms from a domain-unaware static analyzer. Our analyzer named Airac(Array Index Range Analyzer for C) collects all the true buffer-overrun points in ANSI C programs. The soundness is maintained, and the analysis' cost-accuracy improvement is achieved by techniques that static analysis community has long accumulated. For still inevitable false alarms (e.g. Airac raised 970 buffer-overrun alarms in commercial C programs of 5.3 million lines and 737 among the 970 alarms were false), which are always apt for particular C programs, we use a statistical post analysis. The statistical analysis, given the analysis results (alarms), sifts out probable false alarms and prioritizes true alarms. It estimates the probability of each alarm being true. The probabilities are used in two ways: 1) only the alarms that have true-alarm probabilities higher than a threshold are reported to the user; 2) the alarms are sorted by the probability before reporting, so that the user can check highly probable errors first. In our experiments with Linux kernel sources, if we set the risk of missing true error is about 3 times greater than false alarming, 74.83% of false alarms could be filtered; only 15.17% of false alarms were mixed up until the user observes 50% of the true alarms.

• The Journal of Information Systems
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• v.26 no.4
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• pp.247-284
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• 2017

Purpose The first purpose of this study is to investigate factors that are likely to influence user's intention to adopt third-party mobile payment platform. A comprehensive study about mobile payment services have used various variables to explain user's use intention based on the theory of reasoned action (TRA) or the theory of planned behavior (TPB). Variables such as simplicity, security, costs, relative advantage, individual mobility, subjective norm, trust, satisfaction, attitude towards use, perceived usefulness, perceived ease of use and so on. Among these factors, we expect to find out the most influential factors effecting user's use intention of the third-party mobile payment services. Second, we also examine whether the most influential factors have the same influence to different third-party mobile payment services by conducting comparative study of Alipay and WeChat Pay. Design/methodology/approach Empirical data for this study were collected from Chinese who has the experience using or have used Alipay or WeChat Pay. Participants needed to be familiar with Alipay or WeChat Pay because such users may be more aware of both the advantages and disadvantages of Alipay and WeChat Pay. We conduct a pilot test using Smart PLS 2.0, which includes 50 Alipay users and 82 WeChat Pay users. The result indicates that all the measurement fit for the context. And then 980 questionnaires were mainly sent out to the college students and the e-mails users randomly. To encourage participation, we give the participants a small gift as a present. Finally, we received a total of 683 replied. Data from respondents who gave incomplete or invalid answers were excluded to assure the validity of the constructs. 79 questionnaires were rejected, finally the valid data are 604 (with 372 Alipay users and 232 WeChat Pay users). Findings The results suggest that users' intention is determined by their trust on third-party mobile payment service and perceived usefulness of use. Comparative study results also indicated that the factors have different influence on Alipay group and WeChat Pay group, which offers a new aspect for academic field, and provides useful information to mobile payment service providers in China.

• Journal of Internet Computing and Services
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• v.12 no.1
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• pp.99-110
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• 2011

Mobile environments rapidly changing and digital convergence widely employed, mobile devices including smart phones have been playing a critical role that changes users' lifestyle in the areas of entertainments, businesses and information services. The various services using mobile devices are developing to meet the personal needs of users in the mobile environments. Especially, an LBS (Location-Based Service) is combined with other services and contents such as augmented reality, mobile SNS (Social Network Service), games, and searching, which can provide convenient and useful services to mobile users. In this paper, we design and implement the prototype of mobile personal assistant (PA) agents. Our personal assistant agent helps users do some tasks by hiding the complexity of difficult tasks, performing tasks on behalf of the users, and reflecting the preferences of users. To identify user's preferences and provide personalized services, clustering and classification algorithms of data mining are applied. The clusters of the log data using clustering algorithms are made by measuring the dissimilarity between two objects based on usage patterns. The classification algorithms produce user profiles within each cluster, which make it possible for PA agents to provide users with personalized services and contents. In the experiment, we measured the classification accuracy of user model clustered using clustering algorithms. It turned out that the classification accuracy using our method was increased by 17.42%, compared with that using other clustering algorithms.