• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.284-286
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• 2009

In this paper, we consider a cognitive radio system operating as secondary user. It uses an empty channel that is not currently used by primary users having the license to the channel. In the previous works, secondary user looks for an empty channel by choosing any channel in order or randomly and by sensing the channel to distinguish whether primary users are using. But if primary user is fixed type, we will find an empty channel faster than the mentioned channel selecting methods by using a method considering prior information about cases that primary user used the channel, since it is possible to analogize the channel access possibility of primary user according to regular time and position. Therefore, we propose a channel searching method based on the channel list for the purpose of reducing the channel searching time and improving throughput of secondary users. Firstly, we determine a weighting value of each channel based on the history of channel activities of primary users. This value is added to current channel state buffer and we search an empty channel from channel with smallest value to one with the biggest value. Finally, we compare the performances of the proposed method with those of the sequential channel searching and the random channel searching methods in terms of the average channel searching time and the average number of transmissions of secondary user.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.2
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• pp.89-98
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• 2007

In this paper the economic value of weather forecasts is valuated for profit-oriented enterprise decision-making situations. Value is estimated in terms of monetary profits (or benefits) resulted from the forecast user's decision under the specific payoff structure, which is represented by a profit/loss ratio model combined with a decision function and a value score (VS). The forecast user determines a business-related decision based on the probabilistic forecast, the user's subjective reliability of the forecasts, and the payoff structure specific to the user's business environment. The VS curve for a meteorological forecast is specified by a function of the various profit/loss ratios, providing the scaled economic value relative to the value of a perfect forecast. The proposed valuation method based on the profit/loss ratio model and the VS is adapted for hypothetical sets of forecasts and verified for site-specific probability of precipitation forecast of 12 hour and 24 hour-lead time, which is generated from Korea meteorological administration (KMA). The application results show that forecast information with shorter lead time can provide the decision-makers with great benefits and there are ranges of profit/loss ratios in which high subjective reliability of the given forecast is preferred.

• Convergence Security Journal
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• v.11 no.3
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• pp.55-66
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• 2011

This research focus on the value of smart phones for university students in Korea, considering on the correlations between the main causes influencing intrinsic value(price attributes, function attributes), network value(learning effects attributes, externalities attributes) user satisfaction, and intentions of repurchase of the smart phones market in Korea. Through the statistical analyses on the 8 hypotheses from a research model, we found that intrinsic value and network value gave an attentive influence on user satisfaction and repurchase intention. Call charge and Liquid crystal display and Design of smart phone have an influenced user satisfaction and repurchase intention.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.8
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• pp.77-83
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• 2012

In this paper, when interference caused by the primary user exists, the capacity performance of the mean value-based power allocation scheme is analyzed and evaluated under the outdated channel environment in spectrum sharing systems. When interference due to the primary transmitter affects the secondary receiver, we derive the upper bound of the ergodic capacity of the mean value-based power allocation scheme in a closed form. Furthermore, based on that, we investigate how interference due to the primary transmitter degrades the ergodic capacity of the secondary user. In simulation results, we show the performance degradation of the secondary user due to interference caused by the primary user. In addition, we show that the region where the mean value-based power allocation scheme outperforms the outdated channel information-based power allocation scheme is reduced as interference by the primary user increases.

• Journal of Korean Society for Quality Management
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• v.44 no.3
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• pp.689-706
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• 2016

Purpose: This study identifies causality in IoT-based healthcare user's experience(playful experience, economical experience), trust, usage, degree of dependence and continuous use intention, especially focused on chinese case. Methods: Face to face interviews was conducted for people who has experience in the use of the Xiaomi Mi band. This study used Partial Least Square(PLS) method with the questionnaires from the interview. Results: IoT-based healthcare users taking playful experience have a strong trust in a positive economic experiences. Also, the user recognizing the experience as an economic one shows stronger intention to use continuously. Conclusion: By getting healthcare users have more economic experience, they have continuous use intention of healthcare product. The empirical findings can be applied to the related companies strategy building.

• Journal of Information Technology Services
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• v.12 no.1
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• pp.51-67
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• 2013

Mobile Instant Messenser (MIM) Market With the market is enlarging and attracting more and more companies. With the market expanding and number of users increasing, the competition in this area will be fierce. In order to gain competitive advantage, it is important to develop a strategy to maximize user value and to grasp the continuous usage intention of users. However, there are currently not enough researches done in this field. Therefore, this paper to study the effects of network externalities and perceived experiential value on perceived usefulness, user satisfaction, and continuous usage intention. The research results showed that the perceived experiential value and vertical compatibility significantly affected user satisfaction, but the perceived network size did not. The perceived network size and vertical compatibility did not affect the perceived usefulness. Also, the economic value, which is a sub-factor of the perceived experiential value, did not affect the perceived usefulness, but the functional value and hedonic value did significantly. The perceived network size significantly affected continuance usage intention, but the perceived network compatibility did not.

• Journal of the Korean Data and Information Science Society
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• v.17 no.1
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• pp.77-86
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• 2006

This study is to investigate the error of prediction value with related variables from the recommended system and to examine the error of prediction value with related variables. To decrease the error on the collaborative recommended system on user based, this research explored the effects on the prediction related response pair between raters' demographic variables and Pearson's coefficient and sparsity. The result shows comparative analysis between existing error of prediction value and conditioned one.

• Asia pacific journal of information systems
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• v.13 no.2
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• pp.1-21
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• 2003

Although the internet community(IC) has been recognized as an increasingly important for better understanding and relationships with customers, few evidence has been accumulated what factors influence IC success. This study posits the characteristics and individual characteristics as key determinants of IC success, and related hypotheses were tested using 230 data. Using user loyalty as a surrogate of IC success, this study found that the three key characteristics of IC-focus, interactivity, and cohesion levels-significantly influence the community user's loyalty. In addition, individual characteristics including personal value propositions(e.g, challenge/ambitious value, economic/rational value) and absorption tendency(e.g., flow level) affect their loyalty levels. This study also found that the determinents of IC user's loyalty defer with different types of community such as entertainment, relationships, and information/opinion sharing communities. These findings are hopefully helpful for the successful and contingent management of IC buildings and operations.

• Journal of the Korean Data and Information Science Society
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• v.18 no.2
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• pp.315-326
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• 2007

The rapid proliferation of wireless networks and mobile computing applications has changed the landscape of network security. Anomaly detection is a pattern recognition task whose goal is to report the occurrence of abnormal or unknown behavior in a given system being monitored. This paper presents a dynamic anomaly detection scheme that can effectively identify a group of especially harmful internal masqueraders in cellular mobile networks. Our scheme uses the trace data of wireless application layer by a user as feature value. Based on the feature values, the use pattern of a mobile's user can be captured by rough sets, and the abnormal behavior of the mobile can be also detected effectively by applying a roughness membership function with both the age of the user profile and weighted feature values. The performance of our scheme is evaluated by a simulation. Simulation results demonstrate that the anomalies are well detected by the proposed dynamic scheme that considers the age of user profiles.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.4
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• pp.135-143
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• 2016

The purpose of this study is to investigate the user's attitude and usage of smart banking application in terms of user's benefits and personalization. While the prior researches on mobile banking adoption focus on the characteristics of service itself, this paper intends to investigate the smart banking application in terms of user's benefits, which are personal value consumers attach to the product or service attributes. Based on prior studies functional benefits, social benefits, experiential benefits, and personalization are identified as affecting factors of the user's attitude and usage of smart banking application. According to the results of multiple regression analysis, all benefit factors(functional benefit, experimental benefit, social benefit) and personalization were found to be significantly related to the user's attitude. Users' attitude on smart banking was found to be significantly related to the real usage as well. This paper has value in that it investigates the attitude and usage of smart banking in terms of benefits.