• Journal of The Korean Association of Information Education
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• v.18 no.2
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• pp.203-212
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• 2014

With regard to recently emerged problems of smartphone addiction among adults and adolescents, this paper researched upper-grade elementary students depending on various demographic factors that have not been studied thoroughly so far. The survey was conducted on 1570 students in grades 4~6 of schools in Gyeonggi province. Results showed that, first, the average rate of smartphone ownership was about 66%. Second, about 1% of the students belonged to high-risk group, 5.7% to at-risk group, and normal user group was 93.3%. Third, based on the demographic factors, grade and academic achievements each was significantly correlated to the type of addiction group. For example, students with poor academic performance or in higher grade were more likely to be highly addictive. Fourth, both groups of at-risk and of normal-user pertaining to these factors - in urban areas, male students, sixth-grade, in dual income families - showed higher addictiveness score. But they were contrasted in the aspects of household economy and academic performance: at-risk group was more addictive in affluent families or excellent academic performance, whereas normal-user group had higher level of addictiveness in case of poor families or lower academic performance.

• Journal of Korea Multimedia Society
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• v.20 no.8
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• pp.1200-1207
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• 2017

Sensors in a smartphone can be used to measure various physical quantities. In this paper, we propose an object localization scheme in a three dimenstional using a smart phone. The proposed scheme estimates the location of an object by observing it from several different points. The direction to the target object and the locations of the observation points are collected at each observation point using the location sensor and the orientation sensor in the smartphone. Based on these observations, the proposed scheme derives three dimensional line of sight vectors and estimates the location of the target object that minimizes the estimation error. We implemented the proposed scheme on an Android smartphone and tested its performance by estimating the height of a building and characteristics of the proposed approach.

• Journal of Home Health Care Nursing
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• v.25 no.2
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• pp.197-208
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• 2018

Purpose: This study investigated the smartphone using time, troubles with smartphone usage, and related factors in Korean adolescent smartphone users. Methods: Data were obtained from 54,603 subjects aged 13 to 18 years in the 2017 13th Korea Youth Risk Behavior Web-based Survey Results: The study analyzed the school type, academic achievement, residence type, weekly average allowance, and usual counselor, perceived stress, happiness, and depression of the subjects showed a significant difference in the variable of troubles experienced by the smartphone user. Multiple sample logistic regression analysis showed that adolescents with low academic achievement (weekday, weekend OR = 1.78, 1.65), low economic status (weekday, weekend OR = 1.17, 1.37), friends with distress counselors (weekday, weekend OR = 1.29, 1.24), weekly average allowance (weekday, weekend OR = 1.85, 1.50), stressed (weekend OR = 1.25), depressed (weekday, weekend OR = 1.26, 1.14), family troubles (weekday, weekend OR = 1.14, 1.15), friendship troubles (weekday, weekend OR = 1.70, 1.38), and academic performance troubles (weekday, weekend OR = 1.28, 1.38) spent more than the average using time on their smartphones. Conclusion: To prevent overdependence on smartphone use among adolescents, a nursing intervention program that relieves stress and lowers depression should be developed.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.27 no.3
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• pp.188-195
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• 2016

Objectives: The aim of this study was to investigate the relationship between internet addiction, smartphone addiction, and psychosocial factors. This study was designed to examine the vulnerability factors for internet and smartphone addiction. Methods: The participants were 1041 children and adolescents in a small and medium-sized cities. All of the participants were evaluated in terms of their demographic characteristics and present use of the internet and smartphone, as well as using internet and smartphone addiction and other psychological scales. Statistical analyses were performed to compare the psychosocial factors between the high risk, potential risk, and general user groups of internet and smartphone addiction. Results: The participants were classified into three groups, the high risk (N=33), potential risk (N=203), and general user (N=805) groups with regard to their internet and smartphone addiction level. There were statistical significantly differences between the groups in terms of the economic status of the family, academic performance, parents, use of internet and smartphone, loneliness, family cohesion, family adaptability, perceived social support, and peer relationship. Conclusion: These results suggest that the internet and smartphone addiction of children and adolescents is related to various psychosocial vulnerability factors.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.3
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• pp.597-604
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• 2011

The various Smartphone platforms that are used currently make difficult to build efficient applications("apps") for Smartphone. Introduction of middleware in the Smartphone environment is being studied to solve this problem. By enhancing interoperability between server systems and Smartphone platforms as introducing this middleware supports efficiently for Smartphone apps to be developed and managed. Thus, the development of this middleware for Smartphone has become essential for the purpose of responding actively to the rapidly expanding Smartphone market. In this research, we designed and implemented Smartphone middleware which optimizes the cost and time for developing new application service and maintaining it. In order to test this implemented middleware's performance and its capabilities, we also developed university Smartphone apps and activated campus twitter.

• The Journal of the Korea Contents Association
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• v.16 no.4
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• pp.729-740
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• 2016

This study was conducted to assess the needs of smartphone application development for self care performance of 374 patients with chronic hepatitis B. The mean age of the subjects was 46.2 years. The patients obtained information about chronic hepatitis B from the internet (41.3%), nurses or doctors (23.8%), television (15.6%), and smartphones (6.2%). The reason that the information about hepatitis B didn't come from a smartphone were 'Lack of useful applications' (75.9%), 'Could not believe the information' (15.0). If the application is developed, subjects replied 'Frequently use' (59.9%), 'When needed' (33.2%). The desired contents were 'Knowledge of disease' (27.1%), 'Drug calender' (16.8%), 'Reference of information' (15.5%), 'Record of lab data' (14.6%). Ability to use the smartphone, depended on age and level of education, however the needs for the development of the smartphone application, there were not differences. Also, there were different desired contents of application, depended on age and level of education. Therefore, when developing smartphone applications for self care performance of chronic hepatitis B patients considering educational level and age, it could be widely utilized as a tool which can help to the self care performance of chronic hepatitis B patients.

• 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.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.6
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• pp.565-570
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• 2015

Supervised machine learning has become popular in discovering context descriptions from sensor data. However, collecting a large amount of labeled training data in order to guarantee good performance requires a great deal of expense and time. For this reason, semi-supervised learning has recently been developed due to its superior performance despite using only a small number of labeled data. In the existing semi-supervised learning algorithms, unlabeled data are used to build a graph Laplacian in order to represent an intrinsic data geometry. In this paper, we represent the unlabeled data as the spatial-temporal dataset by considering smoothly moving objects over time and space. The developed algorithm is evaluated for position estimation of a smartphone-based robot. In comparison with other state-of-art semi-supervised learning, our algorithm performs more accurate location estimates.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.4
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• pp.270-275
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• 2005

As the features of mobile phones are being enhanced and the performance is being greatly improved, the generic operating systems are being incrementally used in mobile phones. However, since the mobile phones have different requirements in both features and performance compared with desktop or server systems, the operating systems for generic systems could not be used without customization and modification. This case study paper describes the design and implementation of a Linux-based smartphone hardware and software. The enhancements and additional implementations in both kernel and middleware layers are explained. As an experiment, the power consumption of the implemented mobile phone under a number of user scenarios has been measured.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.3
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• pp.273-284
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• 2020

The performance of Global Navigation Satellite System (GNSS) chipset and Inertial Measurement Unit (IMU) sensors embedded in smartphones for location-based services (LBS) is limited due to the economic reasons for their mass production. Therefore, it is necessary to efficiently process the output data of the smartphone's embedded sensors in order to derive the optimum navigation values and, as a previous step, output performance of smartphone embedded sensors needs to be verified. This paper analyzes the navigation performance of such devices by processing the raw measurements data output from smartphones. For this, up-to-dated versions of smartphones provided by Samsung (Galaxy s10e) and Xiaomi (Mi 8) are used in the test experiment to compare their performances and characteristics. The GNSS and IMU data are extracted and saved by using an open market application software (Geo++ RINEX Logger & Mobile MATLAB), and then analyzed in post-processing manner. For GNSS chipset, data is extracted from static environments and verified the position, Carrier-to-Noise (C/N₀), Radio Frequency Interference (RFI) performance. For IMU sensor, the validity of navigation and various location-based-services is predicted by extracting, storing and analyzing data in static and dynamic environments.