• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.149-154
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• 2017

Performance of the mobile devices, such as Smartphones, is sensible by the early-stage of the execution of the applications. To addressing this issue, the dynamic frequency scaling by the ondemand governor has an inherent weakness by the sampling period that may induces some delay in the execution time of the applications. In this paper, we propose an adaptive sampling method that varying the sampling period of the ondemand governor in accordance with the execution of the applications. By the experiment result, the proposed method outperforms 3.34% in early-stage of the execution time that impacts the sensible performance, and exhibits negligible differences in terms of the energy consumption.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.1
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• pp.193-198
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• 2011

As smartphone use has been steadily growing over the past year, social networking on the mobile phones appears to be increasing. In this paper, we propose a cross-platform mobile architecture for supporting social applications. The key design objectives for developing the proposed system include: 1) providing personalized data through filtering information which is supplied by various social applications, 2) providing a cross-platform architecture for adapting various smartphones such as Apple iPhone and Google android. We verified system design by implementing a smartphone application which displays the filtered pictures from social network services such as Flickr and Picasa.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.4
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• pp.743-755
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• 2013

In recent years, the malicious apps with malicious code in normal apps are increasingly redistributed in Android market, which may incur various problems such as the leakage of authentication information and transaction information and fraudulent transactions when banking apps to process the financial transactions are exposed to such attacks. Thus the financial authorities established the laws and regulations as an countermeasures against those problems and domestic banks provide the integrity verification functions in their banking apps, yet its reliability has not been verified because the studies of the safety of the corresponding functions have seldom been conducted. Thus this study suggests the vulnerabilities of the integrity verification functions of banking apps by using Android reverse engineering analysis techniques. In case the suggested vulnerabilities are exploited, the integrity verification functions of banking apps are likely to be bypassed, which will facilitate malicious code inserting attacks through repackaging and its risk is very high as proved in a test of this study. Furthermore this study suggests the specific solutions to those vulnerabilities, which will contribute to improving the security level of smartphone financial transaction environment against the application forgery attacks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.666-668
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• 2013

Recently, the kind and number of malicious code, which operates in Operation System of smart devices, are rapidly increasing along with the fast supplement of smart devices. Especially, smart devices based on Android OS have high potential of danger to expose to malicious code as it has an easy access to system authority. When using intent, the global message system provided from Android, inter approach between applications is available, and possible to access to created data by the device. Intent provides convenience to application development in the aspect of reusability of component however, it could be appointed as a risk element in security-wise. Therefore, if intent is used in malicious purpose, it is easy to lead the condition where is weak on security. That is, it is possible to control as accessing to resources which application is carrying to operate by receiving intents as making smart device uncontrollable or consuming system resources. Especially, in case of system authority is achieved, the risks such as smart device control or personal information exposure become bigger when misusing broadcast intent through malicious code. This paper proposes a corresponding method of security vulnerability of Android intent that monitors the appearance of intent with intent pattern inspection, detects and blocks unidentified pattern intent.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.1
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• pp.17-24
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• 2023

Mobile apps frequently request permission to access sensitive data for user convenience. However, while using mobile applications, sensitive and personal data has been leaked even if users do not allow it. To deal with this problem, Google App Store has required developers to disclose how the mobile app handles user data in a privacy policy. However, users are not certain that the privacy policy describes all the app's behavior. They have no choice but to rely on the privacy policy to confirm how the app uses data. This study designed a system that checks the reliability of privacy policies by analyzing the privacy policy texts and mobile apps. First, the system extracts and analyzes the privacy policy texts to check which personal data the privacy policy discloses that the mobile apps can collect. After analyzing which data apps can access using android static analysis, we compare both results to analyze the reliability of privacy policies. For the experiment, we collected the APK files and metadata of about 13K android apps registered in the Google Play Store and preprocessed the apps by four conditions. According to the comparison between privacy policies and mobile app behavior, many apps can access more personal data than disclosed in the privacy policy.

• Journal of Computing Science and Engineering
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• v.9 no.3
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• pp.155-162
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• 2015

The last decade has seen a rapid growth in the use of mobile devices all over the world. With an increasing use of mobile devices, mobile applications are becoming more diverse and complex, demanding more computational resources. However, mobile devices are typically resource-limited (i.e., a slower-speed CPU, a smaller memory) due to a variety of reasons. Mobile users will be capable of running applications with heavy computation if they can offload some of their computations to other places, such as a desktop or server machines. However, mobile users are typically subject to dynamically changing network environments, particularly, due to user mobility. This makes it hard to choose good offloading decisions in mobile environments. In general, users' mobility can provide some hints for upcoming changes to network environments. Motivated by this, we propose a mobility model of each individual user taking advantage of the regularity of his/her mobility pattern, and develop an offloading decision-making technique based on the mobility model. We evaluate our technique through trace-based simulation with real log data traces from 14 Android users. Our evaluation results show that the proposed technique can help boost the performance of mobile devices in terms of response time and energy consumption, when users are highly mobile.

• Journal of Digital Convergence
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• v.12 no.7
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• pp.189-196
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• 2014

Mobile applications are significantly impacting people's smart phone using behavior and mobile industry value chain. By examining sources of data on mobile applications use, this study presents evidence about what factors would affect the amount of apps download, which may be useful to guide app designers and publishers to develop more persuasive new apps and marketing strategies. The results indicated app ranking had effect on download amount of apps in both Android app market and Apple app store, while prices of apps had no impact on the amount of download. App type, developer experience, and locality had effect on the amount of download only for paid apps in Apple app store.

• Journal of Digital Contents Society
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• v.18 no.1
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• pp.115-121
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• 2017

The Korea metropolitan areas have the largest of population density in OECD countries. Those people who use public transportation is facing many difficulties in commuting and going to school. There are many applications to help this situation. However, those applications inform a regular timetable and also offer a real-time alarm to user by user's passive action. In this paper, we design and implement the application that give the real-time traffic information and the arrival notification message about subway, bus and foot to user.

• KIISE Transactions on Computing Practices
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• v.21 no.3
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• pp.215-222
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• 2015

In this paper, the Digital DoorLock by Internet of Things (DDiT) is introduced. In order to implement DDiT, an integrated micro-controller platform, Arduino is used to control an existing digital doorlock and an android type smart phone is adopted as a mobile platform. One of the advantages of DDiT is that it can be added to an existing digital doorlock and a smart phone application is used as a digital key. Owing to the smart phone application, several other types of applications could also be made. Therefore, DDiT could be used effectively and conveniently in ordinary homes as well as in high security applications such as in hotels, institutes, and companies.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.149-156
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• 2013

With a rapid growth of smartphone technologies, various applications are developed and diffused actively nowadays. Especially, interesting applications using camera module in a smartphone are developed continuously, mobile users are able to use various useful mobile services in humdrum life. In this paper, we design and implement measurement algorithms which precisely measure the object taken by the camera module in a smartphone. We use 3-axis gyro accelerometer sensor in a smartphone to get the distance, incline and rotation angle in a real time when we take a picture of shooting object and can obtain precise size of it in the picture image. The measurement algorithms proposed in this paper are analyzed and evaluated by a simulation study.