• KIPS Transactions on Computer and Communication Systems
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• 제5권11호
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• pp.411-418
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• 2016

Context-aware application has a lot of power consumption because it creates context by using a number of smartphone's sensors. Furthermore, only few kinds of researches have been conducted that provide information for the evaluation result of power consumption in the aspect of applications. In addition, evaluation of power consumption do not consider user's usage pattern or provide only total amount of power consumption, and inform developers power consumption of sensors undistinguishable. It makes developers hard to develop a power consumption-considered application. If developers could get information for power consumption of context-aware application in detail, a development of power-considered context-aware applications would be possible. Consequently, this paper proposes a BMT(Bench Mark Test) model which is able to inform developers useful evaluation criteria and result about power consumption of smartphone's components and sensors with usage pattern considered.

• The Korean Journal of Food And Nutrition
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• 제29권3호
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• pp.363-370
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• 2016

The purpose of this study is to investigate the dietary life status according to smart device use among university students. In 2015, data was collected during a 3 month survey of the eating behaviors, lifestyles, eating habits, and use of smart devices of 550 university students, as well as their dependency on smartphones. Ultimately, 520 subjects (94.5% analysis rate) were divided into three groups based on their daily use time of smart device: low-use group (<4.7 hours, n=173), medium-use group (${\geq}4.7hours$ and <6.4 hours, n=174), and high-use group (${\geq}6.4hours$, n=173). The more frequent use groups showed a higher level of dependency on the smartphone. Breakfast was found to be the most commonly skipped meal; and the high-use group showed a higher response of irregular meals than low-use group. In assessment of eating habits, the subjects with less smart device usage ate more regularly and at fixed times, did not overeat, drank milk everyday, and did not consume processed food as often. To sum up, more irregularity of meal and undesirable eating habits were found among university students with higher use of smart devices. These results suggest that a control of smart device usage would lead to a more desirable dietary life in university students.

• Journal of Digital Convergence
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• 제15권4호
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• pp.451-459
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• 2017

This study investigates the usage of smartphones in English listening activities. 71 students answered the 10-item questionnaire after doing listening activity using their own smartphone for one semester in the course of Practical English listening and reading. The findings show that listening activity done with smartphone enhanced students' interest in English listening and improved their English listening skills because smart phones made customized learning possible. However, the major limitation of using smart phone is that students are distracted during activity by smart phones' other functions such as SMS and messenger. To reduce such distraction, I suggest that individual listening activity with smart phones be mixed with instructor-led activity using a classroom computer in about 50 to 50 ratio. The ratio might vary depending on the level of students' English listening skills. These findings will make a contribution to the boost of digital convergence English learning.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제41권10호
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• pp.1309-1316
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• 2016

This paper suggests adjusting TCP for smartphones that often have small size data transmission tendency. Usage of smartphones has been risen dramatically in recent years, including frequent usage of real-time map search, public transportation search, online games, and SNS. Because the small size data transmission ends before the phase of the TCP congestion avoidance, this paper suggests an algorithm that increases the transmission speed ahead of the traffic congestion event. The algorithm reduces unnecessary delay by data size-driven adjustment of the Linux Quick ACK and Nagle's algorithm. Therefore, TCP is improved to maintain a high transmission rate steadily in small data transmission.

• Korean Journal of Community Nutrition
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• 제24권5호
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• pp.395-407
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• 2019

Objectives: This study examined the association of the sleep quality and patterns with the dietary behavior, including snack and beverage consumption, taste preferences, as well as lifestyle of university students. Methods: The subjects were 406 university students in Cheongju, Korea, and the data were collected using a self-administered questionnaire. They were divided into two groups according to the Pittsburgh Sleep Quality Index (PSQI): good-quality sleepers (PSQI score ≤ 5) and poor-quality sleepers (PSQI score > 5). The data were analyzed using a χ²-test, independent t-test, and analysis of covariance using the SPSS 25.0 program. Results: Fifty-two percent of university students were categorized as poor-quality sleepers by the PSQI. Students classified as poor-quality sleepers had delayed bedtimes, and a shorter duration in bed and total sleep hours than the good-quality sleepers did. Poor-quality sleepers were more prevalent among those who were female, having irregular mealtimes, or frequent late night meals. They also consumed fast food frequently, such as fried chicken and hamburgers, and noodles when adjusted for gender. In addition, drinks with caffeine over milk were dominant among poor-quality sleepers. Furthermore, the preferences for spicy and salty tastes and longer smartphone usage were more prevalent in those with poor-sleep quality. Conclusions: These results showed that more than 50% of university students reported disturbed sleep and poor quality sleep was associated with less desirable snack consumption and taste preference, more smartphone usage, and others. Therefore, nutrition education program along with lifestyle changes promoting sufficient sleep are encouraged to provide for university students, particularly those who have poor sleep quality.

• Journal of the Korea Convergence Society
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• 제10권5호
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• pp.125-131
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• 2019

This study tries to grasp the factor that affects the acceptance of beacon as an O2O marketing tool. This study examined whether there is a difference between beacon accepter as a means of marketing communication and non-accepter in terms of related variables. As a result, there were significant differences between beacon perceiver and non-perceiver in 'smartphone usage' and 'brand consciousness'. In order to understand the predictive variables influencing beacon acceptance as a means of marketing communication, this study used 'perceiving beacon as a marketing communication media' as a dependent variable to perform logistic regression analysis. As a result of the analysis, it was found that 'smartphone usage' and 'brand consciousness' were the predictive variables affecting beacon perceiving. This study tried to analysis the results in the viewpoint of perceived usefulness and ease-of-use which were insisted by TAM.

• Journal of Digital Convergence
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• 제13권7호
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• pp.359-366
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• 2015

The media addiction of teenagers became a social problem in the era of media convergence. With the national efforts, parents has limited their children's media usage for proper parenting. However, current media environment where personalized media devices such as smartphone and tablet PC are common raises questions about whether the problems of media addiction can be solved with previous approaches. Thus, this study examines how the parental controls to teens' media usage affect their media usage and emotions. According to the results that analyzed 884 teens' responses, the parental controls did not affect their usage. On the other hand, it was appeared that excessive parental controls stimulated to teens' negative emotions. These results show that parental controls are not longer effective in current media environment, which implies that new efforts from their family or government are required in order to prevent teens' media addiction.

• Asia pacific journal of information systems
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• 제23권4호
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• pp.1-28
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• 2013

Given that smartphone-based social network services (SNS), such as KakaoStory is now being widely used as a way for people to connect and communicate with each other, this study examines key factors leading to the continued use of SNS. People have been using PC-based SNS, such as Cyworld, for years are now using smartphone-based SNS, such as KakaoStory. KakaoStory developed by KakaoTalk has rapidly grown up as the largest smartphone-based SNS in Korea as smartphone penetration increases. It is more difficult for firms to maintain their current users over time in that alternative SNSs satisfying people's new needs are constantly emerging and evolving. In this sense, one of the most challenging issues for SNS firms is how to retain their current users in the long run. However, there are few empirical studies on this issue. Applying the IS continuance model proposed by Bhattacherjee [2001], this study explores key determinants of users' smartphone-based SNS continuance intention. The model suggests that perceived usefulness and user satisfaction are the key determinants of IS continuance intention. However, the model includes only the utilitarian value that users can obtain through the use of smartphone-based SNS, by considering perceived usefulness. Therefore, the study attempts to extend the IS continuance model by considering hedonic and social values simultaneously. More specifically, we consider subjective norms as social value that are proposed by the theory of reasoned action and the theory of planned behavior. We also consider perceived enjoyment as hedonic value that is emphasized as a key factor influencing users' behavior intention and actual behavior, particularly in the context of hedonic IS use. By considering the three values in our model simultaneously, we could offer a deeper understanding of smartphone-based SNS continuance. That is, this study could offer an explanation of how each value is associated with user satisfaction and SNS continuance intention. The customer value-satisfaction-loyalty model can strengthen the assertion that smartphone-based SNS continuance intention is determined by various different types of customer values, such as utilitarian, hedonic, and social ones. Moreover, the model provides a theoretical basis for the assertion that customer values lead to increased loyalty via customer satisfaction. In this regard, we theorize that SNS continuance intention is influenced by users' various values, namely perceived usefulness, perceived enjoyment, and subjective norms, via user satisfaction. To test the proposed research model and hypotheses, we conducted a partial least squares analysis using a total of 253 data collected on the users of smartphone-based SNS (i.e., KakaoStory). The key findings are as follows: First, it has been found that SNS continuance intention considerably depends on user satisfaction. Second, user satisfaction is determined by confirmation, perceived usefulness, and perceived enjoyment. Third, concerning the effects of the three values on SNS continuance intention, only perceived enjoyment regarded as hedonic value was statistically significant. That is, perceived usefulness considered as utilitarian value and subjective norms considered as social value had no effect on SNS continuance intention. Finally, our results indicate that confirmation increases perceived usefulness, perceived enjoyment, and user satisfaction. The results reconfirm the effectiveness of IS continuance model in predicting smartphone-based SNS continuance intention. Moreover, the results demonstrate that perceived enjoyment reflecting hedonic value is the most important predictor of SNS continuance intention. Therefore, it is imperative for firms to meet SNS users' hedonic value to retain them in the long run. Meanwhile, we could not find any empirical evidence to support the assertion that subjective norms are associated with user satisfaction and SNS continuance intention. The results lead us to conclude that when users have enough direct experience in SNS use, subjective norms have no effect on SNS continuance intention. Discussions and implications of the results are provided.

• Journal of Korea Game Society
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• 제12권3호
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• pp.11-24
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• 2012

Primarily working on SNS(Social Network Service) platform, the SNG(Social Network Game) utilizes friends and neighbors for invitation and play. Based on the value model of HCI, this paper purports to discover how functional, hedonic, social and personal values predict the continuous usage intention and satisfaction of SNG in a smartphone. Hypothesis testing through structural equation modeling shows that hedonic and functional values affect satisfaction and intention to use of SNG while social and personal values do not. This result implies that fun and easy interface are more important to the success of SNG service than social networking motivation.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제63권7호
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• pp.987-993
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• 2014

Pitching machines have been around for many years for casual amusement purpose or professional athletes' training usage, and so forth. The current pitching machines are usually built on the firm ground and do not have any mobility function. In this paper, we develop a pitching machine that has both ball-shooting and mobility functions. Our developed pitching machine consists of two parts. The upper body part has a function of shooting a ball using two DC motors and the lower body part has a function of mobility like mobile robots by using two wheels governed by DC motors. All these functions are operated wirelessly by Android smartphones via bluetooth. The control of each DC motor is done by ${\epsilon}$-PID control method in which the gain tuning is simplied by using a single parameter ${\epsilon}$. Simulation and actual experiment show that our developed pitching machine has both nontrivial shooting and mobility features.