• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1511-1518
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• 2007

As studies on ubiquitous computing are actively conducted, desire for various services, including image transmission storage, search and remote monitoring. has been expanding into mobile environment as well as to PCs. while CCTV (closed circuit TV) and un DVR (Digital video Recording) are used in places where security service such as intrusion detection system is required, these are high-end equipment. So it is not easy for ordinary users or household and small-sized companies to use them. Besides, they are difficult to be carried and camera solution for mobile device does not support high-quality function and provides low-definition of QVGA for picture quality. Therefore, in this study, design and implementation of embedded system of high-definition image transmission for ubiquitous mobile device which is not inferior to PC or DVR are described. To this end, usage of dedicated CPU for mobile device and design and implementation of MPEG-4 H/W CODEC also are examined. The implemented system showed excellent performance in mobile environment, in terms of speed, picture quality.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.1
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• pp.31-36
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• 2024

Recently, mobile apps that utilize AI technologies are increasing. In the personal mobile environment, performance degradation may occur during the training phase of large AI workload due to limitations in memory capacity. In this paper, we extract memory reference traces of AI workloads and analyze their characteristics. From this analysis, we observe that AI workloads can cause frequent storage access due to weak temporal locality and irregular popularity bias during memory write operations, which can degrade the performance of mobile devices. Based on this observation, we discuss ways to efficiently manage memory write operations of AI workloads using persistent memory-based swap devices. Through simulation experiments, we show that the system architecture proposed in this paper can improve the I/O time of mobile systems by more than 80%.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.3
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• pp.101-112
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• 2007

Hard disks have been the most prevalent secondary storage devices and these days their usage is becoming more important in mobile computing systems due to I/O intensive applications such as multimedia applications and games. However, significant power consumption in the disk drives still limits battery lifetimes of mobile systems critically. In this paper, we show that using several smaller disks (instead of one large disk) can be an energy-efficient secondary storage solution on typical mobile platforms without a significant performance delay. Also, we propose a novel energy-efficient technique, which clusters related data into groups and migrates the correlated groups to the same disk. We compare this method with the existing data concentration scheme, and also combine them. The experiments show that our technique saves the energy consumption up to 34% when a pair of 1.8' disks is used instead of a single 2.5' disk with a negligible increase in the average response time. The results also show that our method also saves up to 14.8% of disk energy consumption and improve the average I/O response time by up to 10 times over the existing scheme.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.821-824
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• 2005

Probe storage is one of the strong candidates for future mobile storage device since it has potential of recording density over I $Tb/in^2$ with r/w speed over 100 Mbps. It also uses silicon-processing technology that suits the purpose of small form factor. In this paper, write characteristics of resistive probe that can rotate the field direction of PZT by field-induced resistance changes in a small resistive region at the apex of the tip will be presented. Also, the relationship between the size of tip and the available write width is investigated for different source bias conditions. For this study, two-dimensional computer simulation ($SILVACO^{TM}$) was performed. With optimum design, the width of the writing electric field can be smaller than 50nm

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.2
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• pp.160-171
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• 2008

MU's mobility patterns can be found from a movement history data. The prediction accuracy and model complexity depend on the degree of application of history data. The more data we use, the more accurate the prediction is. As a result, the location management cost is reduced, but complexity of the model increases. In this paper, we classify MU's mobility patterns into four types. For each type, we find the respective optimal number of application of history data, and predictive location area by using the simulation. The optimal numbers of four types are shown to be different. When we use more than three application of history data, the simulation time and data storage are shown to increase very steeply.

• Journal for History of Mathematics
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• v.18 no.1
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• pp.103-110
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• 2005

This paper is aimed at studying a historical background of graph theory and we deal with the computer representation of graph through a simple example. Graph is represented by adjacency matrix, edge table, adjacency lists and we study the matrix representation by Euler circuit. The effect of the matrix representation by Euler circuit economize the storage capacity of computer. The economy of a storage capacity has meaning on a mobile system.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.572-578
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• 2003

In this paper, we present an integrated management system for radioactive waste, which can keep watch on the whole transporting process of each drum from nuclear power plant temporary storage house to radioactive waste storage house remotely. Our approach use RFID(Radio Frequency Identification) system, which can recognize the data information without touch, GSP system, which can calculate the current position precisely using the accurate time and distance measured from satellites, and the spread spectrum technology CDMA, which is widely used in the area of mobile communication.

• Transactions of the Society of Information Storage Systems
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• v.5 no.1
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• pp.1-7
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• 2009

Recently, the growing market demand for small and slim mobile phone cameras requires the size reduction of the camera module. In this paper, an auto-focusing actuator for camera phones is proposed by converting the rotational motion by a rotary VCM actuator into the linear motion using a novel cam structure. This new concept for auto-focusing module enables the reduction of the module thickness and low power consumption. This paper presents the theoretical analysis and optimal design for VCM actuator, cam structure and preload spring. Finally, the experimental results using a prototype with the size of $9.9{\times}9.9{\times}5.9\;mm^3$ are compared with the theoretical predictions.

• Transactions of the Society of Information Storage Systems
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• v.5 no.1
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• pp.8-13
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• 2009

In this study, to compensate trembling of camera caused by vibration of user's hand, 2-axis voice coil actuator of optical image stabilizer (OIS) is suggested. In consideration of actuating performance, volume of OIS and application of hall sensor, one of concept models is selected and it is optimized to maximize the actuating performance. Two types of mechanisms that have the feasibility of moving in 2-axis and the capability of including the optimized EM circuit are proposed. Finally both types are fabricated and then actuating performance of OIS actuator and behavior of hall sensor are verified through the experiment.

• Transactions of the Society of Information Storage Systems
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• v.5 no.1
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• pp.14-18
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• 2009

This paper proposed an optimal plate spring design for the optical image stabilizer in mobile phones. The voice-coil motor (VCM) with plate spring is the smallest, lowest-cost solution for auto focus on the market today and it is also the simplest to implement. The VCM is selected in this paper for auto focusing. However, the design process is complex due to the many design variables coupled to each other and some constraints of each directional motion caused by the characteristics of plate spring. Because of the complex formulation of the design objective, a plate spring design is proposed through the design of experiments to find the optimal design satisfying design constraints.