• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.932-935
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• 2002

In this paper, we introduce new FTL(Flash Translation Layer) driver algorithm that tolerate the power off errors. FTL driver is the software that provide the block device interface to the upper layer software such as file systems or application programs that using the flash memory as a block device interfaced storage. Usually, the flash memory is used as the storage devices of the mobile system due to its low power consumption and small form factor. In mobile system, the state of the power supplement is not stable, because it using the small sized battery that has limited capacity. So, a sudden power off failure can be occurred when we read or write the data on the flash memory. During the write operation, power off failure may introduce the incomplete write operation. Incomplete write operation denotes the inconsistency of the data in flash memory. To provide the stable storage facility with flash memory in mobile system, FTL should provide the fault tolerance against the power off failure. SSR (Simple Sector Remapper) is a fault tolerant FTL driver that provides block device interface and also provides tolerance against power off errors.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권1호
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• pp.1-17
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• 2017

Mobile Cloud Computing has become a promising computing platform. It moves users' data to the centralized large data centers for users' mobile devices to conveniently access. Since the data storage service may not be fully trusted, many public verification algorithms are proposed to check the data integrity. However, these algorithms hardly consider the huge computational burden for the verifiers with resource-constrained mobile devices to execute the verification tasks. We propose an energy-efficient algorithm for assigning verification tasks (EEAVT) to optimize the energy consumption and assign the verification tasks by elastic and customizable ways. The algorithm prioritizes verification tasks according to the expected finish time of the verification, and assigns the number of checked blocks referring to devices' residual energy and available operation time. Theoretical analysis and experiment evaluation show that our algorithm not only shortens the verification finish time, but also decreases energy consumption, thus improving the efficiency and reliability of the verification.

• 정보통신설비학회논문지
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• 제10권4호
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• pp.115-120
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• 2011

Recently flash memory is widely used in various mobile devices as storage medium. Nonvolatile memory can be divided into two categories: NAND- and NOR-type flash memory. NOR flash memory is mainly used to store instruction codes for operation; while NAND for data storage. However, NAND does show more economical benefits, that is, it is approximately 30~40% cheaper than NOR flash. Therefore it can be useful to improve NAND flash performance by replacing NOR flash with NAND flash combining with various buffer systems.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.173-176
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• 2004

Nowadays, mobile devices are very common equipments such as mobile phone, PDA, etc. These equipments need information storage devices. Optical storage devices have more advantages than other storage devices, but it is not free from shock situation like dropping by user's mistakes. A complete model of a Small Form Factor Optical(SFFO) disk drive subject to shock loads is developed to investigate the response of the pickup/disk interface. With this model, we can simulate the drop test and consider the matters of shock simulation using commercial software(Ansys/LS-Dyna).

• Journal of Information Processing Systems
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• 제14권4호
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• pp.989-1009
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• 2018

Rapid advances in science and technology with exponential development of smart mobile devices, workstations, supercomputers, smart gadgets and network servers has been witnessed over the past few years. The sudden increase in the Internet population and manifold growth in internet speeds has occasioned the generation of an enormous amount of data, now termed 'big data'. Given this scenario, storage of data on local servers or a personal computer is an issue, which can be resolved by utilizing cloud computing. At present, there are several cloud computing service providers available to resolve the big data issues. This paper establishes a framework that builds Hadoop clusters on the new single-board computer (SBC) Mobile Raspberry Pi. Moreover, these clusters offer facilities for storage as well as computing. Besides the fact that the regular data centers require large amounts of energy for operation, they also need cooling equipment and occupy prime real estate. However, this energy consumption scenario and the physical space constraints can be solved by employing a Mobile Raspberry Pi with Hadoop clusters that provides a cost-effective, low-power, high-speed solution along with micro-data center support for big data. Hadoop provides the required modules for the distributed processing of big data by deploying map-reduce programming approaches. In this work, the performance of SBC clusters and a single computer were compared. It can be observed from the experimental data that the SBC clusters exemplify superior performance to a single computer, by around 20%. Furthermore, the cluster processing speed for large volumes of data can be enhanced by escalating the number of SBC nodes. Data storage is accomplished by using a Hadoop Distributed File System (HDFS), which offers more flexibility and greater scalability than a single computer system.

• 로봇학회논문지
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• 제6권1호
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• pp.49-57
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• 2011

In many industries, the accurate and quick checking of goods in storage is of great importance. Most today's inventory checking is based on bar code scanning, but the relative position between a bar code and an optical scanner should be maintained in close distance and proper angle for the successful scanning. This requirement makes it difficult to fully automate the inventory information/control systems. The use of RFID technology can be a solution for overcoming this problem. The mobile robot presented in this paper is equipped with an RFID tag scanning system, that automates the otherwise manual or semi-automatic inventory checking process. We designed the robot system in a quite practical approach, and the developed system is close to the commercialization stage. In our experiments, the robot could collect information of goods stacked on shelves autonomously without any failure and maintain corresponding database while it navigated predefined paths between the shelves using vision.

• 정보저장시스템학회논문집
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• 제9권2호
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• pp.56-61
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• 2013

The recent increased use of mobile phone has resulted in a technical focusing on reliability issues related to drop performance. Since mobile phone may be dropped several times during their use, it is required to survive common drop accidents. The plastic injection parts such as base stopper and carrier in the encoder type actuator can be broken easily in the actual reliability test of 1.5m free drop. So, we analyzed the shock resistance characteristics of auto focus actuator with variables in the material properties using finite element method. By applying the new resin materials, we can decrease the breakage of plastic injection parts and improve the reliability of mobile phone.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2008년도 춘계 종합학술대회 논문집
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• pp.38-42
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• 2008

2000년대를 맞이하면서 국내에서는 PC 패키지 게임시장이 쇠퇴하고 유선 인터넷을 기반으로 한 온라인 게임과 무선 인터넷을 기반으로 한 모바일게임, 그리고 가정용 게임기를 중심으로한 고성능 콘솔게임이 새로운 게임 플랫폼의 주류로 자리잡게 되었다. 그중에서도 모바일게임은 시간과 장소의 제약을 극복하는 '이동성'이라는 특징으로 인해 폭발적으로 성장하였다. 그러나, 타 플랫폼과는 달리 모바일게임은 콘텐츠를 사용자의 휴대단말기에 탑재하기 위해서 고가의 무선인터넷 요금을 지불하여야 하고, 휴대단말기의 하드웨어에 장착된 저장 메모리 공간의 부족으로 인해 게임 콘텐츠의 용량 제한이라는 한계를 극복해야하는 문제점이 있다. 모바일게임 콘텐츠의 용량은 주로 이미지 데이터의 용량이 대부분을 차지하므로, 본 논문에서는 이미지 데이터 처리의 최적화를 위한 기술을 압축방식과 이미지 포맷을 유형별로 구분하여 분석함으로써 용량이 제한된 모바일 단말기상에서 최적화된 이미지 데이터들을 포함한 콘텐츠를 제작할 수 있는 방안을 제시한다.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2001년도 The Pacific Aisan Confrence On Intelligent Systems 2001
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• pp.186-191
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• 2001

Mobile agent technologies are getting popular as means for accessing network resources efficiently. In order for mobile agents to be accepted as a reliable technology for applications such as e-commerce, a proper framework for mobile database should be established. In this paper, we first discuss weak points of current mobile computing systems that mostly result from the limitations of current mobile computing technology including frequent disconnection, limited battery capacity, low-bandwidth communication and reduced storage capacity. These weak points also have become the cause of transaction problem where mobile devices issue transactions. In order to eliminate this transaction problem in the mobile environment, we propose a mobile database framework, Proxyne, which is based on the proxy and SyncML.

• 정보처리학회논문지D
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• 제15D권5호
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• pp.609-620
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• 2008

모바일 단말에서의 맵 데이터 활용 서비스는 내비게이션, 위치기반서비스 등 그 활용 범위가 다양해지고 있다. 이러한 모바일 단말에서 저장/관리되는 맵 데이터의 크기는 갈수록 커져 수 GB에 이른다. 기존 내비게이션 시스템의 경우, 리소스 제약으로 인해 모바일 단말의 성능을 최대로 활용하기 위하여 맵 데이터를 읽기 최적화된 물리적인 저장형식(PSF: Physical Storage Format)으로 저장 관리하고 있다. 즉, 맵 데이터가 변경된 경우 변경된 부분만의 업데이트가 불가능하여 전체 데이터를 업데이트해야 하는 단점이 있다. 일반적으로 2 GB 데이터를 모바일 단말의 플래시메모리에 기록하는 시간은 수십 분이 소요된다. 따라서 본 연구에서는 이러한 기존의 내비게이션용 맵 데이터의 부분 업데이트가 불가능한 점을 해결하고자 모바일 공간 DBMS을 개발하였다. 그리고, 모바일 공간 DBMS에서의 내비게이션 서비스의 성능을 보장하기 위한 기법을 제시하고 실험을 통하여 이를 검증하였다.