• International journal of advanced smart convergence
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• v.9 no.2
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• pp.68-75
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• 2020

Non-orthogonal multiple access (NOMA) has gained the significant attention in the fifth generation (5G) mobile communication, which enables the advanced smart convergence of the artificial intelligence (AI), the internet of things (IoT), and many of the state-of-the-art technologies. Recently, correlated superposition coding (SC) has been proposed in NOMA, to achieve the near-perfect successive interference cancellation (SIC) bit-error rate (BER) performance for the stronger channel users, and to mitigate the severe BER performance degradation for the weaker channel users. In the correlated SC NOMA scheme, the stronger channel user BER performance is even better than the perfect SIC BER performance, for some range of the power allocation factor. However, such excessively good BER performance is not good for the user-fairness, i.e., the more power to the weaker channel user and the less power to the stronger channel user, because the excessively good BER performance of the stronger channel user results in the worse BER performance of the weaker channel user. Therefore, in this paper, we propose the power splitting to establish the user-fairness between both users. First, we derive a closed-form expression for the power splitting factor. Then it is shown that in terms of BER performance, the user-fairness is established between the two users. In result, the power splitting scheme could be considered in correlated SC NOMA for the user-fairness.

• Asia pacific journal of information systems
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• v.14 no.1
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• pp.101-123
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• 2004

User satisfaction has been widely used by information system(IS) researchers as the most appropriate surrogate variable for the systems success since Bailey and Pearson(1983) provided their user satisfaction measurement. Because user satisfaction is a perceived performance measure by users, not a real or objective measure for systems success, however, perceived user satisfaction by users may not be exactly identical with the real systems performance. In this regard, if the user's ultimately perceived satisfaction is different from the real systems performance, we need to investigate why these two measures are different and which factors may cause the difference. From the perspective of disconfirmation of user expecations, this study examined why user satisfaction and real systems performance may not be identical each other. Expectaion-disconfirmation theory which has had a central role in marketing in explaining the effects of expectation and disconfirmation on consumer satisfaction was similarly adopted in this study to explain the role of expectation and disconfirmation in user satisfaction in the IS environment. Based on the expectation-disconfirmation theory, the current study developed a research model to examine the effects of expectation, system performance, and disconfirmation on user satisfaction in particular. Six research hypotheses derived from the research model were empirically tested using the partial least squares(PLS) method. The results of the statistical analysis indicate that the effects of system performance and disconfirmation were fairly strong on user satisfaction, while the user's expectation has shown insignificant influences on user satisfaction.

• Journal of the Korean Association of Geographic Information Studies
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• v.1 no.1
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• pp.70-85
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• 1998

This study intends to identify the effects of user attitude, user education & training on the information systems implementation performance. In order to obtain data, survey questionnaires were distributed to the users of 'D' company, the major findings can be summarized as follows. First, it's suggested from the analyses that user attitude and user education & training independently have statistically significant effects on information systems implementation performance. Second, it's revealed that even though the interaction effects by both user attitude and user education & training have positive effects on the level of usage, but have no statistically significant effects on satisfaction level. Based on these results, it's recommended to convert user attitude favorably toward user environment and to increase the level of user education & training, in order to promote information systems implementation performance. Especially, differentiated user education & training are highly recommended.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1998.10a
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• pp.28-31
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• 1998

This paper describes the differences of the information system's success factors to improve the end-user's performance according to the job characteristics. A modified model of DeLone and McLean's IS success model is proposed with the two added variables of the top management concern and the IS department support. The model is validated using data collected from a field study of 3872 users on 3 Korean companies. ANOVA, correlation analysis, and stepwise regression are used to test research hypotheses. The results of the study indicate the following implications. First the top management concern and the IS department support have the significant relation with the system usage and the user satisfaction. Second, the system quality has an influence on the user satisfaction more than on the system usage. And the information quality has an influence on the system usage more than on the user satisfaction. Third, the system usage has more relations to the user's performance in the logistics function and R&D function. The user satisfaction has more relations to the user's performance in the sales and the A/S function. Therefore information system strategy to increase the user's performance must be differentiated according to job characteristics.

• Journal of Information Technology Services
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• v.8 no.3
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• pp.111-134
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• 2009

We are living it what is referred to as the Digital Era; a time in which communication through the computer medium has deeply infiltrated our everyday lives and is now equivalent to face-to-face communication. In other words, e-communication is the core factor of knowledge sharing, for not only individuals but also for corporations, and its efficiency has increased gradually. At this time, studies on the factors affecting the outsourcing performance of e-communication channel services are gaining importance. Therefore, the purpose of this study is to empirically analyze the effects of the system, information, and service quality on the user satisfaction and user trust of e-communication channel outsourcing, as well as the effects of user satisfaction and user trust on the outsourcing performance of both individuals and organizations. In the results of the empirical study, the system, Information, and service quality appear to have a significant effect on both user satisfaction and user trust. In addition, user satisfaction and user trust appear to also have a significant effect on the outsourcing performance of both Individuals and organizations.

• Journal of Nutrition and Health
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• v.38 no.2
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• pp.180-189
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• 2005

The purposes of this study were 1) to analyze the effect of the ERP quality (system quality, information quality, service quality) on the performance (end user satisfaction, user's performance, system utilization) of business, 2) to conduct the causal-effect analysis between outcome variables (user's satisfaction, user's performance, system utilization) of ERP in the contract foodservice management company. The questionnaires were distributed to 260 end users (dietitians, foodservice management managers) in charge of managing the institutional foodservice such as the office (government agencies, factories), schools (universities, middle and high school) and hospitals which were managed by contract foodservice management company 'C' in Seoul and Kyunggi. The surveys were performed from July 26, 2004 to July 30. 2004. Two hundred and fifty (250) questionnaires were responded (response rate: 96.2%). The statistical analysis was conducted using SPSS Win (11.5). And the descriptive analysis, factor analysis, reliability test, pearson correlation, simple and multiple regression analysis were performed. The results showed that among the 3 factors (system quality, information quality, service quality), the system quality and information quality were proved to have an effect on the user's satisfaction and user's performance significantly (p < .05). The influence of ERP quality (system quality, information quality, service quality) on system utilization were testified to be statistically significant (p < .05). The user's performance were affected significantly by system utilization (p < 0.001) and end user's satisfaction (p < 0.001). As a conclusion, to improve user satisfaction, which is the ultimate performance variable of an ERP system, high quality of an ERP system is the pre-requisite. And the user satisfaction and performance of business would be higher with the better quality ERP system. When constructing ERP system for the contract foodservice management company, we should improve system utilization and user satisfaction altogether so that user's performance could be ultimately enhanced and we should make efforts to enhance the quality level of ERP. (Korean J Nutrition 38(2): 180～189, 2005)

• Korean Management Science Review
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• v.21 no.2
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• pp.111-122
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• 2004

Measuring performance of corporate information system has become one of the core issues in that development of the information system requires substantial amount of investments and the system works as a crucial leverage to enhance competitive edge. Most of the previous researches for performance of the information system have narrow and limited focus on such as the effect of user satisfaction and productivity. This paper suggests a model to measures the comprehensive performance which is classified as user scope (user involvement and satisfaction), operational scope (task productivity, task innovation, customer satisfaction, management control) and efficiency scope (financial performance), and to represent the relationship among the scopes by the path analysis model. Followings are conclusions from statistical hypothesis test of the model: (i) user involvement through user satisfaction has positive effect on all the performances in the operational scope, (ii) task innovation and customer satisfaction in the operational scope has statistically significant impact on financial performance but task productivity and management control do not. This conclusion indicates that task productivity and management control has the long term effect in nature, and evaluation of the information system has managerial implication when it Is measured in comprehensive performance which includes internal operational performances as well as financial performance.

• International journal of advanced smart convergence
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• v.11 no.1
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• pp.36-41
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• 2022

Recently, to improve the performance of the strongest channel gain user in non-orthogonal multiple access (NOMA) with a non-uniform source and symmetric superposition coding (SSC), a novel bit-to-symbol (BTS) mapping have been proposed. However, only the performance of the user with the stronger channel gain was analyzed. Thus, we compare the bit-error rate (BER) of the new BTS scheme with that of uniform sources, especially for the user with weakest channel gain. First, we show that the performance of the novel BTS scheme for the user with weakest channel gain also improves, compared to that of the uniform sources. Furthermore, the signal-to-noise (SNR) gain of the new BTS scheme over the uniform sourcesis calculated. As a consequence, the novel BTS scheme would improve the performance of the user with weakest channel gain as well as that with the stronger channel gain for SSC NOMA with a non-uniform source.

• The Journal of Information Systems
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• v.16 no.1
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• pp.179-200
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• 2007

In this research, we study how task and KMS fit influences on KMS performance in large corporations during its practical use. Based on the task-technology fit theory and information system success model, we developed a research model by considering the characteristics of KMS for supporting tasks. We try to verify how individual traits, task traits, and KMS Units affect task-KMS fit and how task KMS fit influences on KMS performance. We surveyed 212 employees who were using KMS and working for the large-sized manufacturing firms. We analyzed the collected data from LISREL 8.54 for Windows, and found the following significant results. First user satisfaction is increased when KMS provides knowledge to help to perform task rather than KMS' functionality. Second, user satisfaction is increased when KMS is suitable for performing task Hence, we verified task-KMS fit is an antecedent of user satisfaction. Third, task-KMS fit and user satisfaction have significant impacts on KMS performance. And user satisfaction affected more heavily on KMS performance than task-KMS fit did. As a result, we realized an individual performance can be improved when task KMS fit is high and, consequently, user satisfaction is increased. Forth while the usefulness of task-KMS fit is demonstrated, causal factors such as individual traits, task traits, and KMS traits significantly affect task-KMS fit. Formalization and knowledge trait we significant in enhancing user satisfaction, but KMS self-efficacy, autonomy, md system trait are not. These results indicate that task-KMS fit variable is useful as a measure of KMS performance as well as that of user satisfaction. Based on these results, we conclude that when KMS supports task activity, performance can be significantly improved by coordinating the task with KMS.

• KIISE Transactions on Computing Practices
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• v.21 no.5
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• pp.379-386
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• 2015

We propose a novel user-perceived performance optimization framework for the Android platform that takes advantage of the user-centric response time analysis. To this end, we propose a new definition of response time, which we call the user-centric response time, as a metric for the quality of user-perceived performance of the smartphone application. In this paper, we describe the design and implementation of an on-line user-centric response time analyzer for Android-based smartphones, which provides smartphone application developers with valuable insight for user-perceived performance optimization. We implemented the user-centric response time analyzer on the Android platform, version 4.0.4 (ICS) running on a Galaxy Nexus smartphone. From our experimental results, the proposed user-centric response time analyzer accurately estimates user-centric response times with an accuracy of 92.0% compared to manually measured times with less than 1% performance penalty. In order to evaluate the efficiency of the proposed framework, we were able to reduce the user-centric response time of the target application by up to 16.4% based on the evaluation results by the proposed framework.