• Journal of information and communication convergence engineering
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• v.11 no.3
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• pp.167-172
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• 2013

Recently, mobile communication systems are suffering from exponentially increasing data traffic. As a promising solution to the increase in data traffic, a coordinated multi-point transmission and reception (CoMP) scheme has been proposed. Although a great deal of research has been done on this new technology, the performance of mobile communication systems with CoMP has not been evaluated properly in a typical indoor environment. To address this, we have developed a system-level simulator and evaluated the performance of mobile communication systems with CoMP. Unlike previous works, we have used an actual antenna pattern in our simulator and link-level results are properly taken into account through link-level abstraction. By using a system-level simulator, we have evaluated the performance of mobile communication systems with CoMP in an indoor environment and found that unlike an outdoor cellular environment, CoMP may not improve the performance of overall mobile communication systems in an indoor environment.

• Korean Journal of Remote Sensing
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• v.22 no.5
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• pp.351-356
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• 2006

Based on current practical needs for geo-spatial information on mobile platform, the main theme of this study is a design and implementation of dynamic 3D terrain rendering system using spaceborne imagery, as a kind of texture image for photo-realistic 3D scene generation on mobile environment. Image processing and 3D graphic techniques and algorithms, such as TIN-based vertex generation with regular spacing elevation data for generating 3D terrain surface, image tiling and image-vertex texturing in order to resolve limited resource of mobile devices, were applied and implemented by using graphic pipeline of OpenGL|ES (Embedded System) API. Through this implementation and its tested results with actual data sets of DEM and satellite imagery, we demonstrated the realizable possibility and adaptation of complex typed and large sized 3D geo-spatial information in mobile devices. This prototype system can be used to mobile 3D applications with DEM and satellite imagery in near future.

• Journal of the Korea Society of Computer and Information
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• v.23 no.11
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• pp.203-209
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• 2018

The purpose of this study was social withdrawal, depression, and self - esteem affect adolescents' mobile phone dependency. For this study, I used data from the first grade of junior high school during the 7th (2016) Korean child and youth panel survey provided by Korea Youth Policy Institute. A total of 1,937 people were selected as the final target except those who do not have a mobile phone. The analysis method was SPSS 23.0 and AMOS 20.0. As a result of the study, First, the higher the depression of adolescents, the higher the dependence on mobile phones. Second, the social withdrawal and depression of adolescents have a significant impact on mobile phone dependence through self-esteem. In conclusion, I would like to provide policy data so that youths can develop and implement preventive programs that can prevent personality education and erroneous mobile phone dependency that can develop healthy and positive growth.

• International Journal of Computer Science & Network Security
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• v.23 no.10
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• pp.73-80
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• 2023

The recent growth in the use of mobile devices has contributed to increased computing and storage requirements. Cloud computing has been used over the past decade to cater to computational and storage needs over the internet. However, the use of various mobile applications like Augmented Reality (AR), M2M Communications, V2X Communications, and the Internet of Things (IoT) led to the emergence of mobile cloud computing (MCC). All data from mobile devices is offloaded and computed on the cloud, removing all limitations incorporated with mobile devices. However, delays induced by the location of data centers led to the birth of edge computing technologies. In this paper, we discuss one of the edge computing technologies, i.e., cloudlet. Cloudlet brings the cloud close to the end-user leading to reduced delay and response time. An algorithm is proposed for scheduling tasks on cloudlet by considering VM's load. Simulation results indicate that the proposed algorithm provides 12% and 29% improvement over EMACS and QRR while balancing the load.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.49-54
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• 2008

Recently, with the development of wireless communications and GIS, interest about mobile computing is rising. In this case, the GIS needs to be placed in a constricted environment than the environment of server computing. For this reason large amounts of spatial data must be compressed into the mobile device. The compression technique of the spatial data is difficult and must be processed in the correct order because the size of the data is unpredictable. Therefore, in this paper, the cell-based compression technique of the spatial data for mobile GIS is presented. This paper includes the process of transformation of spatial data from a certain server to a mobile device by cell-based compression technique. In this paper, the cell-based compression technique of the spatial data has been proven practically efficient.

• Information Systems Review
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• v.6 no.1
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• pp.155-166
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• 2004

As the necessity of such mobile wireless terminals as PDAs or Cellular phones drastically increases, the terminals play important role in various business areas. In this paper, a bidding system in mobile wireless environments is constructed. However, with many mobile wireless terminals modifying at the same time their (duplicated) bidding values for a given data item, data coherency for the data item becomes essential. Therefore, in this paper, a bidding system using SyncML data synchronization mechanism is proposed and constructed. SyncML is one of data synchronization mechanisms proposed by the SyncML Initiative, a consortium of mobile wireless mobile technology leaders for universal data synchronization. The bidding system is implemented and tested in LINUX, C++, and PocketPC 2000 emulator programming environments.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.3
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• pp.405-415
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• 2020

With the increase in smartphone user, mobile forensics has become an essential element in modern digital forensic investigation. Mobile messenger data is very important data in mobile forensics because it can acquire information such as user's life pattern and mental state. In order to analyze messenger data, a decryption technique of an encrypted messenger data is required. Since most messengers provide a message deleting function, a technique for recovering deleted messages is required. WeChat Messenger, a messenger used by about 1 billion people around the world, uses IMEI (International Mobile Equipment Identity) information to encrypt data and provides message deletion function. In this paper, we propose a data decryption method in the absence of IMEI information and propose a method for recovering deleted messages using FTS (Full Text Search) database created for full-text search function of SQLite database.

• Journal of Korea Multimedia Society
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• v.7 no.5
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• pp.680-688
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• 2004

In this paper, we propose a new handoff scheme which is efficient in hybrid mobile data network consists of cellular mobile network and wireless LAN. In this scheme, handoff is delayed until connections with wireless LAN and data rates are smoothly decreased according to becon signal strength of wireless LAN. By doing so, data transfer capacity is increased and required data buffer in handoff for mobile and network system can be decreased. We analyze new handoff scheme by computer simulation. The results show that 180Mbytes data can be transferred additionally in handoff processing and required buffer size can be decreased 1/2 with the conditions that mobile speed is 1Km/hr and the data rate of a original call is 2,048Kbps.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.1039-1044
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• 2008

Owing to rapid advancements of the mobile computing technologies and the performance of mobile device recently, the data synchronization techniques between severs and mobile clients are getting more and more important. OMA also proposes and recommends standard synchronization methods to use SyncML. However, the feasible data in the method are limited to normal document data, scheduler data, etc. This paper a standard framework based on SyncML. We call it SCGFG. The SCGFG is able to synchronize not only the above data but also GIS data which is very useful in mobile applications. It applies GML, international GIS standard, to the synchronization. By means of using XML, it is also able to resolve the serious problem that is the increase of data volume occurred by SyncML and GML. efficiently. It is highly expected to be useful in the smart synchronization of GIS data among several servers and mobile clients.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.7
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• pp.167-176
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• 2019

Recently, as the types of services that can be enjoyed in mobile telecommunication networks such as social networks and video streaming are increasing, mobile users(MUs) can access mobile contents easily by consuming mobile data. However, under a mobile telecommunication environment, MUs have to pay a high data fee to a network service provider(SP) in order to enjoy contents. The 'data sponsor' technique, introduced as a way to solve this problem, has attracted attention as a breakthrough method for enhancing contents accessibility of MUs. In this paper, we propose an algorithm that determines the optimal discount rate through the Stackelberg game in the data sponsor environment. We also propose an algorithm to design edge caching, which caches highly popular content for MUs on edge server, through many-to-many matching game. Simulation results clearly indicate that the profit for CP's content consumption is improved by about 6~11%, and the profit of CP according to the ratio of edge caching is improved by about 12% than the other existing schemes under data sponsor environment.