• Journal of KIISE:Information Networking
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• v.29 no.3
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• pp.265-275
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• 2002

A default server strategy is a very popular scheme for managing location and state information of mobile hosts in cellular networks. But the communication cost increases if the call requests are frequent and the distant between the default server and the client is long. Still more any connection to a mobile host cannot be established when the default server of the destination mobile host fails. These problems can be solved by replicating default server and by letting nearest replicated default server process the query request which is sent from a client. It is important to allocate replicated default servers efficiently in networks and determine the number of replicated default servers. In this paper, we suggest and evaluate a default server replication strategy to reduce communication costs and to improve service availabilities. Furthermore we propose and evaluate an optimized allocation algorithm and an optimal replication degree for replicating: dofault servers in nn grid networks and binary tree networks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3916-3936
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• 2014

Smartphone applications like games, image processing, e-commerce and social networking are gaining exponential growth, with the ubiquity of cellular services. This demands increased computational power and storage from mobile devices with a sufficiently high bandwidth for mobile internet service. But mobile nodes are highly constrained in the processing and storage, along with the battery power, which further restrains their dependability. Adopting the unlimited storage and computing power offered by cloud servers, it is possible to overcome and turn these issues into a favorable opportunity for the growth of mobile cloud computing. As the mobile internet data traffic is predicted to grow at the rate of around 65 percent yearly, even advanced services like 3G and 4G for mobile communication will fail to accommodate such exponential growth of data. On the other hand, developers extend popular applications with high end graphics leading to smart phones, manufactured with multicore processors and graphics processing units making them unaffordable. Therefore, to address the need of resource constrained mobile nodes and bandwidth constrained cellular networks, the computations can be migrated to resourceful servers connected to cloud. The server now acts as a bridge that should enable the participating mobile nodes to offload their computations through Wi-Fi directly to the virtualized server. Our proposed model enables an on-demand service offloading with a decision support system that identifies the capabilities of the client's hardware and software resources in judging the requirements for offloading. Further, the node's location, context and security capabilities are estimated to facilitate adaptive migration.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.561-564
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• 2001

본 논문은 무선 에플리케이션 프로토콜 Specification에서 제시하고 있는 WTA(Wireless Telephony Application) 를 기초로 네트워크에서 발생한 실시간 Event를 처리할 수 있는 모바일 클라이언트 및 WTA서버에 대한 설계와 구현에 대해서 기술한다. 또한 네트워크 이벤트 및 사용자가 발생시킨 이벤트를 디바이스에 독립적으로 처리할 수 있는 WTA 라이브러리와 필요한 컨텐츠를 실시간으로 브라우징하기 위한 Repository 에 대해 기술한다. 전체적인 WTA 환경 구조는 크게 2개의 물리적 구조인 Mobile Client와 WTA Server로 구현되어있다. Mobile Client의 내부 모듈은 표준 WAE 사용자 에이전트(Standard WAE User Agent)의 확장인 WTA 사용자 에이전트 모듈(WTA User-Agent Module), 필요한 resource를 서버로 요청하고 저장하는 채널 인스톨 모듈(Channel Install Module), network로부터 발생한 Event를 처리하는 이벤트 핸들러 모듈(Event Handler Module), mobile network 기능들(e.g. setting up calls)과 device specific feature(e.g. manipulating the phonebook)를 다루는 WTA 스크립트 라이브러리(WTA Script Library), Phonebook 엑세스 모듈(Phonebook Access Module), 실시간으로 즉각 이벤트에 반응하기 위한 Repository로 구성되어있고, WTA Server는 Client가 요청한 Content(services)를 전달 해 주는 컨텐트 전달 모듈(Content Deliver Module)과 서버 Phonebook 엑세스 모들(Server Phonebook Access Module)로 구성되어 있다.

• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.19-26
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• 2010

The most critical element in the real-time operation of RFID application programs that are suitable for the mobile environment is the RFID middleware, made exclusively for mobile handsets, which processes collected data on a real-time basis and sends only the useful information to the application client. In this paper, we intend to design and implement the Pet management system for optimized mobile RFID middleware that supports real-time data processing. The proposed Pet management system consists of registration module, retrieval module, communication module, and display module in order to display retrieval result from server. Also, the captured data in the PDA is transmitted to the server and another client system using the mobile application interface that supports the SOAP application access protocol.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.621-624
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• 2013

Mobile Cloud Computing is today's emerging technology. Customers enjoy the services and application from this combination of mobile technology and cloud computing. Beside all these benefits it also increases the concerns regarding privacy of users, while interacting with this new paradigm One of the services is Location based services, but to get their required services user has to give his/her current location to the LBS provider that is violation of location privacy of mobile client. Many approaches are in literature for preserve location privacy but some has computation restriction and some suffer from lack of privacy. In this paper we proposed a novel idea that not only efficient in its protocol but also completely preserves the user's privacy. The result shows that by sharing just service name and a large enough geographic area (e.g. a city) user gets required information from the server by doing little client side processing We perform experiments at client side by developing and testing an android based mobile client application to support our argument.

• Journal of the Korea Computer Industry Society
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• v.4 no.10
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• pp.547-558
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• 2003

This paper is a parking management system which uses mobile terminal equipment by the client. From the Web server, the client will be served about the information concerned with the location o( parking lot, parking time, and payment after accessing the parking management web site. After the sensor which is set in the parking lot perceives the information about the client's car, it will inform the client of the parking place. This system is designed to control the large and complex parking lot and serves a very convenient interface to the user.

• Journal of Computing Science and Engineering
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• v.5 no.4
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• pp.331-337
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• 2011

Recently, Virtual Desktop Infrastructure (VDI) has been widely adopted to ensure secure protection of enterprise data and provide users with a centrally managed execution environment. However, user experiences may be restricted due to the limited functionalities of thin clients in VDI. If thick client devices like laptops are used, then data leakage may be possible due to malicious software installed in thick client mobile devices. In this paper, we present Data Firewall, a security framework to manage and protect security-sensitive data in thick client mobile devices. Data Firewall consists of three components: Virtual Machine (VM) image management, client VM integrity attestation, and key management for Protected Storage. There are two types of execution VMs managed by Data Firewall: Normal VM and Secure VM. In Normal VM, a user can execute any applications installed in the laptop in the same manner as before. A user can access security-sensitive data only in the Secure VM, for which the integrity should be checked prior to access being granted. All the security-sensitive data are stored in the space called Protected Storage for which the access keys are managed by Data Firewall. Key management and exchange between client and server are handled via Trusted Platform Module (TPM) in the framework. We have analyzed the security characteristics and built a prototype to show the performance overhead of the proposed framework.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.8
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• pp.1153-1160
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• 2002

So far, the main applications of mobile client are querying data. However, we need a new mechanism to update data at a mobile client as mobile systems are advanced and extended. So, we present a optimistic concurrency control to schedule mobile transactions may include update operations.'rho read-only transactions can be terminated without sending information to a server, and update transactions are terminated by validating at a server. In our method, we can reduce the additional aborts by using a timestamp ordering and serialization graph test mechanism rather than using only conflict information between concurrent transactions.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.3
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• pp.270-274
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• 2002

This paper presents a teleoperation system that combines computer network and an autonomous mobile robot. We control remotely an autonomous mobile robot with vision over the Internet to guide it under unknown environments in the real time. The main feature of this system is that local operators need a web browser and a computer connected to the communication network and so they can command the robot in a remote location through the home page. The hardware architecture of this system consists of an autonomous mobile robot, workstation, and local computers. The software architecture of this system includes the client part for the user interface and robot control as well as the server part for communication between users and robot. The server and client systems are developed using Java language which is suitable to internet application and supports multi-platform. Furthermore. this system offers an image compression method using JPEG concept which reduces large time delay that occurs in network during image transmission.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2272-2279
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• 2014

Mobile applications are software systems running on handheld devices, such as smartphones, PDAs, tablets and so on. The market of mobile application has rapidly expanded in the past few years. In this paper, we present a novel approach to track smartphone application usage from a event logs on the mobile device and analyzed both on client system and usage analysis server. We implemented our client system on Android device based usage analytics platform. Based on the analysis server system, we obtained over 47,000 user base, and we get the user's app usage informations on realtime. In this paper, we describe a large scale deployment-based research for a smartphone usage patterns and usage information visualization techniques.