• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.755-761
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• 2003

Recently, the development of mobile devices demands information storage systems to use micro drive devices and cheap media. These should have several characteristics, for example, the subminiature of size, the robustness of shock, the minimum of cost and power consumption, and the removability of multiple applications. A conventional optical disk drive is more suitable for these specifications than the others. The optical storage system of the new generation to use a blue laser and a high numerical aperture (NA) is the perfect candidate for micro optical disk drives. In this paper, the micro actuator that can be applied to a micro optical disk drive is designed by response surface methodology to use a structural analysis and an electro-magnetic analysis. Based on above results, the coarse actuator and fine actuator are designed and improved from the point of view of the size and the power. Consequently, the designs of a micro actuator are proposed through these courses.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2012년도 제46차 하계학술발표논문집 20권2호
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• pp.73-74
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• 2012

스마트 모바일 장치는 HD 디지털 컨텐츠가 창조될 수 있도록 했고, 사용자가 어디있든간에 그것을 접하는 것이 가능할 수 있도록 하였다. 그러나 스마트 모바일 장치는 저장공간의 제약과 같은 필연적인 하드웨어 제약이 있다. 이 논문에서 우리는 사용자들이 그들의 집에있는 데이터에 매끄럽게 접근할 수 있는 이해하기 쉬운 WebDAV 기반 가상 저장 시스템(DAVSS)을 제안한다. 우리가 구현한 프로토타입 결과물은 저장공간이 한정된 장치에 제안된 해결책(DAVSS)이 실현가능함을 보여준다.

• 반도체디스플레이기술학회지
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• 제9권2호
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• pp.67-72
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• 2010

Recently increasing application of flash memory in mobile and ubiquitous related devices is due to its non-volatility, fast response time, shock resistance and low power consumption. Following this trend, SSD(Solid State Disk) using multiple flash chips, instead of hard-drive based storage system, started to widely used for its advantageous features. However, flash memory based storage subsystem should resolve the performance bottleneck for writing in perspective of speed and lifetime according to its disadvantageous physical property. In order to provide tangible performance, solutions are studied in aspect of reclaiming of invalid regions by decreasing the number of erasures and distributing the erasures uniformly over the whole memory space as much as possible. In this paper, we study flash memory recycling algorithms with multiple management units and demonstrate that the proposed algorithm provides feasible performance. The proposed method utilizes the partitions of the memory space by utilizing threshold values and reconfigures the management units if necessary. The performance of the proposed policies is evaluated through a number of simulation based experiments.

• Journal of applied mathematics & informatics
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• 제39권5_6호
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• pp.805-811
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• 2021

Currently, batteries use commonly as energy sources for mobile electric devices. Due to the high density of energy, the energy storage state of a battery is very important information. To know the battery's energy storage state, it is necessary to find out the open state voltage of the battery. The open state voltage calculates with a mathematical model, but the computation of the real time state is complicated and requires many calculations. Therefore, the state observer designs to estimate in real time the battery open-circuit voltage as disturbance including model error. Using the estimated open voltage and applying it to the state estimation algorithm, we can estimate the charge. In this study, we first estimate the open-circuit voltage and design an estimation algorithm for estimating the state of battery charge. This includes errors in the system model and has a robust characteristic to noise. It is possible to increase the precision of the charge state estimation.

• Journal of applied mathematics & informatics
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• 제39권5_6호
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• pp.851-858
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• 2021

In general, secondary batteries are widely used as an electric energy source. Among them, the state of energy storage of mobile devices is very important information. As a method of estimating a state, there is a method of estimating the state by integrating the current according to an energy storage state of a battery, and a method of designing a state estimator by measuring a voltage and estimating a charge amount based on a battery model. In this study, we designed the state estimator using an extended Kalman filter to increase the precision of the state estimation of the charge amount by including the error of the system model and having the robustness to the noise.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제14권4호
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• pp.378-388
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• 2008

플래시 메모리는 전력 소모가 작고 충격과 진동에 강하며 크기가 작다는 특성 때문에 최근 노트북이나 UMPC(Ultra Mobile PC)와 같은 이동 컴퓨팅 시스템에서 하드디스크를 대체할 대용량 저장 매체로서 주목 받고 있다. 플래시 메모리에 기반한 저장 장치는 일반적으로 랜덤 읽기 성능이나 순차 읽기, 순차 쓰기 성능이 매우 좋은데 비해, 덮어쓰기가 불가능한 플래시 메모리의 물리적인 제약으로 인하여 소량의 랜덤 쓰기 성능은 떨어진다. 본 논문은 이 문제를 해결하기 위한 두 가지 중요한 특징을 갖는 SSD(Solid State Disk) 아키텍처를 제안하였다. 첫 번째로 비휘발성 이면서도 SRAM과 동일한 인터페이스로 덮어쓰기가 가능한 작은 크기의 FRAM(Ferroelectric RAM)을 NAND 플래시 메모리와 함께 사용하여 소량 쓰기 오버헤드를 최소화하였다. 두 번째, 호스트 쓰기 요청들도 소량 랜덤 쓰기와 대량 순차 쓰기로 분류하여 각각에 대해 최적의 쓰기 버퍼 관리 방법을 적용하였다. 평가 보드 상에서 SSD 프로토타입을 구현하고 PC 사용 환경의 워크로드에 기반한 벤치마크를 이용하여 성능을 평가해 본 결과 랜덤 패턴을 보이는 워크로드에서는 하드디스크나 기존의 상용 SSD들에 비해 처리율(throughput) 측면에서 3배 이상의 성능을 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권11호
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• pp.5653-5672
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• 2019

In cloud computing era, an increasing number of resource-constrained users outsource their data to cloud servers. Due to the untrustworthiness of cloud servers, it is important to ensure the integrity of outsourced data. However, most of existing solutions still have challenging issues needing to be addressed, such as the identity privacy protection of users, the traceability of users, the supporting of dynamic user operations, and the publicity of auditing. In order to tackle these issues simultaneously, in this paper, we propose a traceable dynamic public auditing scheme with identity privacy preserving for cloud storage. In the proposed scheme, a single user, including a group manager, is unable to know the signer's identity. Furthermore, our scheme realizes traceability based on a secret sharing mechanism and supports dynamic user operations. Based on the security and efficiency analysis, it is shown that our scheme is secure and efficient.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.351-351
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• 2004

For greeting the era of ubiquitous network, data storage devices have been essentially attached to mobile data devices. As a result, the minimization of the storage device has arisen as major interests in the next generation data storage technology. So, there are many researches for the small form factor ODD. In this paper, we propose a pick up that consists of a linear VCM and 2-wire focusing actuator for a small form factor ODD. For the sake of checking performance of the coarse actuator, PID controller is designed. Experiment with controller and DSP board shows its propriety as a fine tracking actuator. And, 2-wire suspension actuator is designed in order to be contained in a coarse actuator and to satisfy the thickness of a PCMCIA type. Through the experiment of designed actuator, It verifies performance as a focusing actuator.

• 디지털콘텐츠학회 논문지
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• 제8권4호
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• pp.593-600
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• 2007

휴대용 기기나 디지털 미디어 기기와 같은 소형 컴퓨터는 저장 매체로 NAND 타입의 플래시 메모리를 사용한다. 하지만 이러한 기기에 사용되는 DBMS의 경우 대부분 하드디스크를 저장매체로 사용되도록 최적화되어 있다. 플래시 메모리를 사용하는 소형 컴퓨터 시스템에서는 DBMS를 사용할 때 플래시메모리를 기존 하드디스크와 같은 인터페이스로 제어하기 위해 플래시전용의 파일시스템이나 FTL 등의 계층을 추가적으로 사용하게 되며, 이 때 DBMS는 플래시 메모리를 직접 제어할 수 없게 된다. 본 논문에서는 DBMS가 파일 시스템이나 FTL과 같은 부가적인 계층 구조를 이용하지 않고 플래시 메모리를 직접 제어할 수 있는 통합된 저장 시스템을 제안한다. 또한 제안한 시스템을 실제 시스템에 직접 구현해 DBMS의 성능이 기존 시스템에 비해 크게 향상됨을 보였다.

• 전자통신동향분석
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• 제39권1호
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• pp.83-94
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• 2024

There have been continuous requirements for developing more reliable energy storage systems that could address unsolved problems in conventional lithium-ion batteries (LIBs) and thus be a proper option for large-scale applications like energy storage system (ESS). As a promising solution, aqueous metal-ion batteries (AMIBs) where water is used as a primary electrolyte solvent, have been emerging owing to excellent safety, cost-effectiveness, and eco-friendly feature. Particularly, AMIBs adopting mutivalence metal ions (Ca²⁺, Mg²⁺, Zn²⁺, and Al³⁺) as mobile charge carriers has been paid much attention because of their abundance on globe and high volumetric capacity. In this research trend review, one of the most popular AMIBs, zinc-ion batteries (ZIBs), will be discussed. Since it is well-known that ZIBs suffer from various (electro) chemical/physical side reactions, we introduce the challenges and recent advances in the study of ZIBs mainly focusing on widening the electrochemical window of aqueous electrolytes as well as improving electrochemical properties of cathode, and anode materials.