• The Journal of the Korea Contents Association
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• v.21 no.4
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• pp.67-76
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• 2021

Three research hypotheses expected when working with a mobile app were verified. As follows: (1) Usability varies depending on the external structure of the tree-view menu. (2) If the menu arrangement is different from the script expected by users, the usability is poor. And (3) the effects of each of these two hypotheses vary depending on the complexity of the task. To this end, a script for booking accommodations expected by undergraduate students was written, and an experiment was designed with the task completion time and error rate as dependent variables. The experiment was conducted by implementing a prototype for reservation system on a smartphone As a result, while the overall performance was unfavorable when the task was complicated, the superiority of sectional menu was prominent when the task was complicated, and positive responses were observed when the menu arrangement in a complicated task matched user expectations. By discussing these results, it was found that when designing a procedural menu on a mobile screen, we come up with measures to minimize the burden of working memory, consider what tree-views are for the task, and that in complex tasks, menus should be arranged according to the scripts expected by users.

• Journal of the Korea Computer Graphics Society
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• v.28 no.3
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• pp.79-89
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• 2022

With the popularity and the advanced graphics hardware technology of mobile devices, various mobile applications that help children with physical activities have been studied. This paper presents SandUp, a mobile application that guides the play of building sand castles using artificial intelligence and augmented reality(AR) technology. In the process of building the sandcastle, children can interactively explore the target virtual sandcastle through the smartphone display using AR technology. In addition, to help children complete the sandcastle, SandUp informs the sand shape and task required step by step and provides visual and auditory feedback while recognizing progress in real-time using the phone's camera and deep learning classification. We prototyped our SandUp app using Flutter and TensorFlow Lite. To evaluate the usability and effectiveness of the proposed SandUp, we conducted a questionnaire survey on 50 adults and a user study on 20 children aged 4~7 years. The survey results showed that SandUp effectively helps build the sandcastle with proper interactive guidance. Based on the results from the user study on children and feedback from their parents, we also derived usability issues that can be further improved and suggested future research directions.

• The KIPS Transactions:PartC
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• v.16C no.3
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• pp.407-416
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• 2009

Recently, various application services in wireless sensor networks are more considered than before, and thus reliable and secure communication of sensor network is turning out as one of essential issues. This paper studies such communication in IEEE 802.15.4 based sensor network. We present IMHRS (IEEE 802.15.4 MAC-based Hybrid hop-by-hop Reliability Scheme) employing EHHR (Enhanced Hop-by-Hop Reliability), which uses Hop-cache and Hop-ack and ALC (Adaptive Link Control), which considers link status and packet type. Also, by selecting security suite depending on network and application type, energy efficiency is considered based on HAS (Hybrid Adaptive Security) Framework. The presented schemes are evaluated by simulations and experiments. Besides, the prototype system is developed and tested to show the potential efficiency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.8
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• pp.1123-1132
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• 2018

In this paper, we design and implement a public bicycle sharing system based on smart phone application capable of distributing access codes via internet connection. When smartphone user uses the application to request a bicycle unlock code, server receives the request and sends an encrypted code, which is used to unlock the bicycle at the station and the same code is used to return the bicycle. The station's hardware prototypes were built on top of Internet devices such as raspberry pi, arduino, keypad, and motor driver, and smartphone application basically includes shared bike rental and return functionality. It also includes an additional feature of reservation for a certain time period. We tested the implemented system, and found that it is efficient because it shows the average of 3-4 seconds delay. The system can be implemented to manage multiple bikes with a single control box, and as the user can use a smartphone application, this makes the system more cost effective.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.4
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• pp.145-152
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• 2018

In electronic textbooks (or e-Textbooks) the traditional paper-based textbooks are enriched with multimedia contents and new features such as interactive multimedia-based simulation, interactive quizzes, and content sharing. It has been envisioned that e-Textbooks will gradually replace the traditional paper-based textbooks in classrooms in the near future. HTML5 is an emerging and promising standard that enables web applications (or apps) to incorporate rich multimedia contents such as video clips, flash movies and simulation-based demonstration, as well as to provide cross-platform functionality which allows the apps to run on a diverse range of platforms. To support rich multimedia contents and cross-platform functionality, with respect to HTML5, this paper presents the new features, compares the current trend of mobile apps (e.g., native, web-based and hybrid apps) for e-Textbook development. In order to investigate the suitability of these three development approaches for e-Textbooks, we present a case study on our recent work in developing e-Textbooks using HTML5 and JavaScript, as well as analyses the challenges associated with HTML5 features (e.g, compatibility with web browsers) for developing e-Textbooks.

• Journal of Internet Computing and Services
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• v.11 no.2
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• pp.41-48
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• 2010

It is essential to guarantee a smooth communication and data exchange in a PHD(Personal Healthcare Device) network for applications providing U-health services. In spite of that, most of PHDs are heterogeneous, so the heterogeneity of their protocols makes it difficult to develop an integrated gateway sending sensed healthcare data to U-health service providers. To solve this problem, we suggest the design and implementation of a device adapter model based on dynamic managed module in this paper. Our model were implemented to work on the OSGi-based gateway middleware and to have interoperability in connection with the HL7 system that is the standard of the Healthcare Information systems. In addition, our model has an architecture supporting a communication based on the object serialization in order to provide extensibility in the functional aspect of applications. Through the experiment on a test-bed which is an implementation of the device adapter module for electrocardiogram and blood-pressure/blood-sugar device having one channel, we have confirmed the accuracy of sensing and sending data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.664-671
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• 2020

A Smart Building, one that uses automated processes to control its operations, refers in this study to one that uses both Internet of Things (IoT) devices and cloud services software. Cloud service providers (e.g. Amazon, Google, and Microsoft) have recently providedIoT cloud platform application services on IoT devices. According to Postscapes, there are now 152 IoT cloud platforms. Choosing one for a smart building is challenging. We selected Microsoft Azure IoT Hub and Amazon's AWS (Amazon Web Services) IoT. The two platforms were evaluated and selected from a smart building perspective. Each prototype was evaluated on two different IoTplatforms, assuming a typical smart building scenario. The selection was based on information and experience gained from developing the prototype system using the IoT cloud platform. The assessment made in this evaluation may be used to select an IoTcloud platform for smart buildings in the future.

• Journal of Satellite, Information and Communications
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• v.7 no.3
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• pp.130-134
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• 2012

This paper introduces a home network service system using a low-cost wireless router on OpenWrt which can be remotely controled by Android devices. The proposed system consists of an embedded system development platform for home network service control based on OpemWrt embedded Linux, an embedded system development platform, a remote control on Android, and a home linghting device made by an interface board with LEDs. The prototype system is made of a wireless router of Buffalo, WZR-HP-G450H, Arduino Uno interface board with LEDs, and an Android development kit of HBE-SM5-S421. The operation was performed by TCP/IP programming for Android remote control, socket programming between Android development kit and wireless router, and UART communication programming between the interface board and wireless router. The implementation result shows that a low cost home network systme could be implemented with a wireless router.

• Journal of the Korea Society of Computer and Information
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• v.19 no.10
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• pp.135-149
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• 2014

This study proposed the ubiquitous learning system by finding the difficulties which students have in learning the course of science and analyzing the current learning applications that are used commercially. Through case studies, we found 4 problems. First, the request of long learning time by most of the existing video-based learning applications. Second, it is impossible to know their level of learning due to the lack of open learning contents. Third, it is difficult for learners to participate in interactive learning. Fourth, there are educational contents without considerations on the level of learners. To refine the difficulties due to these problems, we designed and implemented a new ubiquitous learning system which applies the small learning contents for short-term learning, open learning system and enhanced hierarchical learning contents. The system was implemented based on Android. It provides learners with useful science education. We conducted a questionnaire for third grade middle school students in order to show that the proposed system has a good educational effects. The questionnaire asks for the differences between the proposed ubiquitous learning system and the existing learning application. We concluded that the proposed system is better than the existing application by using t-test for improvement of learning effects using feedback with which students participate in interactive learning but not in unidirectional learning, and share the learning result.

• The Journal of Society for e-Business Studies
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• v.21 no.1
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• pp.79-90
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• 2016

Autonomous knowledge service, a fully-automated and pervasive service for knowledge acquisition and support based on the power of recent ITs is gaining tremendous interest more and more, as not only the level of users' intelligence increases but also the maturity of IT infrastructure improves. Conventional approaches of knowledge service, however, could not satisfy users because they usually provided undesired knowledge which had been acquired without considering users' want. In other words, knowledge acquisition and distribution were separately performed. This research, therefore, suggests an amended autonomous knowledge service framework by fully-automating the whole phases of knowledge life cycle, from knowledge acquisition to distribution. ASKs, the prototype system of this research, is also implemented by defining and specifying component technologies which constituently compose suggested framework. More user-friendly and applicable way of knowledge service will be derived and facilitated through this research.