• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3329-3350
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• 2017

Installing caching and computing facilities in mobile edge networks is a promising solution to cope with the challenging capacity and delay requirements imposed on future mobile communication systems. The problem of optimal facility placement in mobile edge networks has not been fully studied in the literature. This is a non-trivial problem because the mobile edge network has a unidirectional topology, making existing solutions inapplicable. This paper considers the problem of optimal placement of a fixed number of facilities in a mobile edge network with an arbitrary tree topology and an arbitrary demand distribution. A low-complexity sequential algorithm is proposed and proved to be convergent and optimal in some cases. The complexity of the algorithm is shown to be $O(H^2{\gamma})$, where H is the height of the tree and ${\gamma}$ is the number of facilities. Simulation results confirm that the proposed algorithm is effective in producing near-optimal solutions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.3
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• pp.835-854
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• 2012

In this paper, we propose a novel positioning system for indoor navigation which helps a user navigate easily to desired destinations in an unfamiliar indoor environment using his mobile phone. The system requires only the user's mobile phone with its basic equipped sensors such as a camera and a compass. The system tracks user's positions and orientations using a vision-based approach that utilizes $360^{\circ}$ panoramic images captured in the environment. To improve the robustness of the vision-based method, we exploit a digital compass that is widely installed on modern mobile phones. This hybrid solution outperforms existing mobile phone positioning methods by reducing the error of position estimation to around 0.7 meters. In addition, to enable the proposed system working independently on mobile phone without the requirement of additional hardware or external infrastructure, we employ a modified version of a fast and robust feature matching scheme using Histogrammed Intensity Patch. The experiments show that the proposed positioning system achieves good performance while running on a mobile phone with a responding time of around 1 second.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.10 s.115
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• pp.997-1004
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• 2006

With the growth in electronics and the remarkable advance in wireless communication technology, mobile devices, such as mobile phones and PDAs are incessantly improved in their diverse functional performance. Lighter weight and smaller size has been gradually accomplished by recent circuit integration technology resulting in rapid growth in the number of mobile phone subscribers. Driven by customer demand, recent mobile devices are fully capable of realizing a variety of dazzling multimedia effects powered by electro-acoustic parts that have become one of the generic components. However, This paper also presents an oval micro-speaker, that is' expected to show an excellent performance within limited space of mobile phone, and its performance design has been suggested as well. Finally, a statistical approach to achieve high characteristic and performance is suggested by Taguchi method to identify a certain relationship between a mobile phone and a micro-speaker.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.6
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• pp.1152-1168
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• 2010

Recently, due to the prevalence of various mobile devices and wireless broadband networks, there has been a significant increase in interest and demand for multimedia streaming services such as the mobile IPTV. In such a wireless broadband network, transmitting a continuous stream of multimedia data is difficult to achieve due to mobile stations (MSs) movement. Providing Quality of Service (QoS) for multimedia video streaming applications requires the server and/or client to be network-aware and adaptive. Therefore, in order to deploy a mobile IPTV service in wireless broadband networks, offering users efficient wireless resource utilization and seamlessly offering user perceived QoS are important issues. In this paper, we propose a new adaptive streaming scheme, called MARC (Mobile-aware Adaptive Rate Control), which adjusts the quality of bit-stream and transmission rate of video streaming based on the wireless channel status and network status. The proposed scheme can control the rate of multimedia streaming to be suitable for the wireless channel status by using awareness information of the wireless channel quality and the mobile station location. The proposed scheme can provide a seamless multimedia playback service in wireless broadband networks in addition to improving the QoS of multimedia streaming services. The proposed MARC scheme alleviates the discontinuity of multimedia playback and allocates a suitable client buffer to the wireless broadband network. The simulation results demonstrate the effectiveness of our proposed scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.1105-1117
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• 2017

Financial technology, also known as FinTech, is one of the fast growing global businesses in since its inception in 2008. Fintech is a new economic industry, comprised of companies that adopted the latest technologies to provide more efficient financial services than the traditional financial services. Fintech companies are generally small to medium sized startups trying to disintermediate existing financial systems. FinTech companies can be differentiated in several areas, based on its business solutions and target customers. In Korea, the Peer-to-Peer (P2P) lending companies are the most prominent in the FinTech sector. P2P lending is a method of borrowing or lending money to individuals through online services without the use of an official financial institution as an intermediary. The P2P lending companies operate their services entirely online or mobile environment. Consequently, mobile P2P lending application users are dramatically increasing. Thus, it is worth evaluating the acceptance of the mobile apps of the P2P lending companies from a user's perspective. This paper discusses user acceptance of the mobile P2P lending apps, guided by the Technology Acceptance Model. We conclude that the users' acceptance of mobile P2P lending apps are significantly influenced by perceived ease of use, perceived usefulness, and user satisfaction. These in turn influenced their attitude towards using mobile P2P lending apps and intention to use.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.10
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• pp.445-460
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• 2013

Mobile applications today are being offered as various services depending on the mobile device and mobile environment of users. This increase in mobile applications has shifted the spotlight to their vulnerability. As an effective method of security verification, this paper proposes "phase-wise security verification for the implementation of mobile applications". This method allows additional security verification by covering specific items across a wider range compared to existing methods. Based on the identified weaknesses, it detects the cause of vulnerability and monitors the related settings.

• Journal of the Korea Society of Computer and Information
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• v.3 no.4
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• pp.19-26
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• 1998

Mobile database system address information processing based on database system in mobile computing environment. In the mobile database system, when a mobile transaction host enter a other radio coverage area called a cell while processing a transaction, it have to alter the communication network address to new database server. This is called transactional service handoff. This paper propose a transaction processing scheme for providing the proper function of this transactional service handoffs in mobile database system. This scheme apply coordinator migration mechanism which perform the transaction in new database server when posed to be the transaction service handoff. Fially, the proposed scheme will improve system performance by minimizing the tansmission of message for processing the transactions in mobile database system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.1
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• pp.85-91
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• 2014

As RFID is utilized more frequently and diversely in terms of its application areas, the application of mobile RFID technology, which integrates cellular networks and RFID, is highly anticipated. The growth and development of the RFID field has bolstered the development of mobile RFID chips to be embedded in mobile phones. Because mobile RFID chips are embedded in cell phones, limitations such as low power, small form factor, and costliness must be confronted. This study presents the design of a RFID digital baseband processor that is suitable for mobile readers. The RF analog component, which affects the baseband signals, is designed separately, in consideration of the limitations stated above. The function of the baseband processor was verified through simulations and prototyped using FPGA. The power consumption of the chip is 20mW under a 20MHz clock and the chip measures $3mm{\times}3mm$.

• The KIPS Transactions:PartA
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• v.19A no.4
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• pp.195-204
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• 2012

M-commerce services are rapidly emerging with recent advances in mobile devices and wireless communications. Internet Shopping mall managers provide mobile phone users with their mobile shopping malls for m-commerce. However, these mobile shopping malls usually have their own sites which are not compatible with their Internet shopping malls, thus resulting in inefficiency to manage the two kinds of shopping malls. In this paper, we develop a M-commerce content provider system to effectively bring Internet shopping malls to mobile phones by extracting items only concerned to users from product documents. We then apply and evaluate the system over a specific internet shopping mall site. The results show that the system reduces considerably the amount of data transferred to user's mobile phones compared with using general web browsers.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.5
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• pp.103-108
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• 2016

In this paper, we propose a resource allocation scheme that guarantees transmission rate for each mobile stations by mitigating interference between a base station-to-mobile station link and a relay station-to-mobile station link. Specifically, we dynamically adjust the boundary between access zone and relay zone using signal to interference plus noise ratio. Moreover, we cluster the mobile stations under sever interference and manage the channel quality of these mobile stations by allocating additional radio resource. Our simulation results show that the proposed scheme can improve the efficiency of radio resources and ensure fairness among mobile stations.