• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.649-651
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• 2014

The Digital Living Network Alliance (DLNA) standard enables easy sharing of multimedia contents in the home network environment. However, with the proliferation of mobile computing devices such as smartphones and tablets, the need for media sharing to expand beyond the boundaries of the home network arose. In this paper, a method for accessing DLNA based home network from the mobile environment is proposed. The proposed method uses mobile Virtual Private Network (VPN), and enables easy access to the resources in the home network from the wireless mobile environment.

• Journal of Korea Multimedia Society
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• v.11 no.8
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• pp.1059-1071
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• 2008

Users in ubiquitous computing environment can easily access and use a multitude of devices and services anywhere and anytime. The key technology to realize this scenario is the method to intuitively provide proper user interfaces for each device and service. Previous attempts simply provided a designated user interface for each device and service or provided an abstract user interface to control common functions of different services. To select a target appliance, either user directly specified the target device or depended on sensors such as RFID tags and readers limiting the applicable scenarios. In this paper, we present UbiController which uniquely uses camera on the mobile device to recognize markers of appliances to acquire user interface for controlling task. UbiController aims to provide automatic discovery of multiple services in the smart home environment, support traditional GUI and novel camera-based recognition method as well as intuitive interaction methods for users. In this paper, we show experiments on the performance of UbiController's discovery and recognition methods and user feedback on interaction methods from a user study.

• Journal of Korea Multimedia Society
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• v.8 no.7
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• pp.953-960
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• 2005

The Network can be easily damaged in the mobile computing environment. Mobile Support Station (MSS) which supports the Mobile Host(MH) could also be unstable too. Therefore, when a critical error occurs the repairing cost can be high. For stable repair, the hand-off strategy should be considered to save the continuing message and checkpoint information, and to reduce the cost of network repair. In this paper, we propose the Switching Trickle(ST) strategy which reduces the repairing cost for the MH's mobility. ST strategy changes the way which stores the information in connection with the number of write events(r) that occur from the hands-off strategy. Accumulated cost by increased mobility has been simulated too. From the results of simulation, the proposed strategy has shown more cost effective than the conventional strategy. The proposed strategy also has shown very supportive in saving checkpoint and message log information stably.

• KIISE Transactions on Computing Practices
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• v.23 no.1
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• pp.13-27
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• 2017

This paper presents a tool that automatically generates mobile web applications from user interface (UI) models which are based on PELUM (Pattern and Event based Logical User Interface Modeling). PELUM is a method for the effective development of UI-centered embedded systems via UI modeling. The proposed tool consists of a model editor and a code generator. The former provides an environment for modeling a Logical UI Model (LUM) and a Programming Interface Model (PIM) on the web. On the other hand, the code generator sets the screen configuration and events' behavior, according to the LUM, synthesizing a local database schema according to the PIM, and then generates an executable mobile web app. It also can produce mashup web apps by receiving an open API address via the PIM. The generated mobile web apps follow the Model-View-Controller (MVC) architecture in order for users to easily customize them. The proposed tool enables them to generate mobile web apps that can be executed on various devices by modeling logical UIs on the web.

• Journal of the Korea Society of Computer and Information
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• v.13 no.6
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• pp.203-210
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• 2008

Recently, as wireless communication are becoming more and more popular, Internet users is becoming increasingly demand HTTP-based web service in mobile computing environment. But, overall performance of web services may slow down, because mobile device are generally equipped with lower capability. Therefore, the most important factor to design wireless internet delivery system should be scalable to handle a large scale traffic due to rapidly growing users. But, in case of some preceding research, they not present a basic efficiency reform measure until currently. Therefore, In this paper, We propose a Web Service Delivery System for mobile environment that alleviates problems that occurred while executing web services in mobile environment and are helpful to overcome the above needs. The system composed of HTML/WML Converter, SOAP message processor. We compare the existing system with the proposed system.

• Journal of Digital Contents Society
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• v.8 no.1
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• pp.17-25
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• 2007

Recently, the ubiquitous computing environment being able to connect all kinds of computing elements at anytime anywhere becomes widespread in human life. In this paper, we focus on a PC remote control system using cellular phones. Especially, we design and implement an mobile e-mail transmission system using PC remote control technique. By using our remote controller, cellular phone users can login into their own PC, and then send any file to others by e-mail attachment. To show the correct running of our system, real demonstration results are presented. We are sure that by opening our source code to the public our results can play an important role to encourage development of the various mobile remote control functionalities.

• Journal of Digital Convergence
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• v.10 no.10
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• pp.465-473
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• 2012

The mobile devices and cloud computing technology introduced new content services such as N-Screen service. The DRM techniques have been developed to support interoperability and multi-platform for new environment of content service. Nevertheless, it is still inconvenient for the consumers to purchase a new DRM-supported device or to migrate some purchased contents into new device due to the change of the subscription of service. Therefore, in this paper, cloud-based DRM model which is referred as DRMaaS (DRM-as-a-Service) model, is proposed to allow the consumer to freely use and move some DRM-protected contents in various smart devices regardless of subscription of service.

• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.59-75
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• 2006

In this paper, we propose a congestion control scheme to control the congestion due to the mobility of ubiquitous devices on ubiquitous computing environment. Especially, this congestion control scheme provides a reverse congestion avoidance state which can classify between packet error by features of wireless network and packet dropping by congestion. Also, it provides a slow stop state which can minimize bandwidth waste due to congestion control. The proposed congestion control scheme controls more adaptive than existing congestion control schemes. The proposed congestion control scheme is designed based on DCCP(Datagram Congestion Control Protocol) being proposed by IETF(Internet Engineering Task Force) and implemented on the Linux kernel. In simulation results, the proposed congestion control scheme provides good bandwidth throughput in wireless network as well as in wired network.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.2
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• pp.85-90
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• 2017

Various mobile devices are spreading in recent developments in mobile computing environments. Especially the popularity of mobile devices equipped with GPS has become widespread, and various application services utilizing location information are born. In this paper, we propose a system model for storing and managing the trajectory of moving objects, which is the set of location information of moving objects acquired in continuous time, and the UDF (User-Defined Functions) based trajectory index method which can quickly query the large data set of moving object and the Pre-Materialized table method. Then we compare and evaluate the performance of each method through experiments. Experimental results show that the Pre-Materialized table method is about 1.2 times faster than the UDF based trajectory index method on execution time.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.3
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• pp.306-310
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• 2008

Since the preference for information recommendation service can change according to the context, we should know the user context before providing information recommendation. This paper proposes recommender system that considers multi-user preference in mobile environment and attempted to apply it to restaurant recommendation. To model the preference of individual users in mobile environment, we have used Bayesian network, and restaurant recommendation mostly should consider not an individual user but several users, so this paper has used AHP of multi-criteria decision making process to obtain the preference of several users based on one of individual users. For experiments, we conducted recommendation in 10 different situations, and finally, we confirmed that the proposed system was evaluated as a good one using a usability test of SUS.