• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.122-124
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• 2000

최근 PC의 고성능화롤 PC 기반의 서버 사용이 증대되고 있다. 특히 Windows NT 는 인터넷 서비스를 제공하는 PC 기반 서버로 폭 넓게 사용되고 있다. 이러한 서버에서의 데이터 파괴는 막대한 손실을 가져 올 것이다. 데이터의 안정성과 고 가용성을 위한 방법으로 disk mirroring 기법이 여러 분야에서 사용되고 있다. 기존의 연구들은 UNIX 플랫폼에 편중되어 있고, 현실적으로 사용이 증대되고 있는 Windows 에 대한 연구는 상대적으로 빈약한 상태이다. 본 논문에서는 Windows NT device driver level에서 다수의 node에 대한 disk mirroring 기능 구현을 설계한다. Windows NT는 계층화된 driver layer로 구성되어 있으며, 구현된 mirroring module을 드라이버 계층상에 추가함으로써 기존의 기능을 변경하지 않고 새로운 기능을 추가할 수 있다.

• KIISE Transactions on Computing Practices
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• v.23 no.2
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• pp.134-139
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• 2017

The existing screen mirroring systems are vulnerable to packet loss and inefficient for mobile devices with limited energy capacity. To overcome these problems, we propose a packet loss robust and energy efficient screen mirroring system for mobile device. The proposed system employs systematic Raptor codes for a forward error correction method to mitigate the video quality degradation that is caused by packet loss over wireless networks. For the mobile device energy saving, the proposed system shapes the screen mirroring traffic and adjusts the Raptor encoding parameters. In this paper, the proposed system is fully implemented on single board computers and is examined in a real Wi-Fi Direct network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.2
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• pp.363-365
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• 2015

Recently, Smart Phone is widely used and replaces with the work of computer system. So, to overcome the inconveniences of Smart-Phone small screen size, a mirroring the screen of Smart Phone to TV or Computer monitor is studied to show a larger screen to the users. In this study, we implemented a screen mirroring and efficient user interface(computer mouse and keyboard) system with Bluetooth and USB host functions for a smart phone using standard 5 pin(MHL compatible) connector output to HDMI Monitor. Dock-style and Monitor embedded system are designed respectively.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.117-119
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• 1999

Disk mirroring 시스템은 안정성과 고 가용성(High Availability)을 제공하기 때문에 고성능 시스템에서 많이 사용되고 있다. 본 논문에서는 Windows NT 커널에 remote node에 대한 disk mirroring 기능을 추가하여 시스템 자체에서 이러한 기능을 제공할 수 있는 모델을 설계하고자 한다. 설계 시스템은 Windows NT TDI 계층을 사용하여 network 으로 연결된 두 대의 시스템이 master node와 slave node의 pair로 구성되며,slave node가 master node의 디스크를 mirror하게 된다. 또한 fault tolerance 기능을 제공하여 node의 장애 발생시 log를 생성하고, 이 정보를 바탕으로 장애가 발생한 node에 대하여 데이터 복구 기능을 제공하도록 한다.

• Journal of Intelligence and Information Systems
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• v.16 no.3
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• pp.37-54
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• 2010

The information system that preserves and presents information collections, records, processes, retrievals, is applied in various fields recently and is supporting man's many activities. Conventional information systems are based on the reactive interaction model. Such reactive systems respond to only specific instructions, i.e. the defined commands, from the user. To go beyond the reactive interaction, it is necessary that the interactive dynamic interaction based information system which understands human's action and intention autonomously and then provides sensible information adapted to the user. Therefore, we propose a Gaze Mirroring-based intelligent information system for making user's latent interest using the internal state estimation methods based on the interactive dynamic interaction. Then, the proposed Gaze Mirroring method is that an anthropomorphic agent(avatar) actively established the joint attention with the user by imitating user's eye-gaze behavior. We verify that the Gaze Mirroring can elicit the user's behavior reflecting the latent interestand contribute to improving the accuracy of interest estimation. We also have confidence that the Gaze Mirroring promotes the self-awareness of interest. Such a Gaze Mirroring-based intelligent information system also provides suitable information to user by making user's latent interest using the internal state estimation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4997-5006
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• 2010

A flash-memory-based SSDs(Solid State Disks) are one of the best media to support portable and desktop computers' storage devices. Their features include non-volatility, low power consumption, and fast access time for read operations, which are sufficient to present flash memories as major database storage components for desktop and server computers. However, we need to improve traditional storage management schemes based on HDD(Hard Disk Drive) and RAID(Redundant array of independent disks) due to the relatively slow or freezing characteristics of write operations of SSDs, as compared to fast read operations. In order to achieve this goal, we propose a new storage management scheme called Hetero-Mirroring based on traditional HDD mirroring scheme. Hetero-Mirroring-based scheme improves RAID-1 operation performance by balancing write-workloads and delaying write operations to avoid SSD freezing. Our test results show that our scheme significantly reduces the write operation overheads and freezing overheads, and improves the performance of traditional SSD-RAID-1 scheme by 18 percent, and the response time of the scheme by 38 percent.

• Journal of Internet Computing and Services
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• v.3 no.5
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• pp.95-106
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• 2002

In current storage system environment, we use disk mirroring or Chained-declustering scheme to improve data availability and reliability. If disk error is occurred when these schemes are used. we need efficient recovery schemes for these situations. In this paper, it is proposed that a recovery method of disk mirroring that guarantees I/O performance similar to normal state during disk failure, Also, we execute performance evaluation for our recovery scheme and existing schemes in various environments. We show through the simulation that our algorithm outperforms the classic schemes in terms of I/O response time.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.07a
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• pp.63-66
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• 2015

본 논문에서는 미러링 환경에서 동작하는 악성링크 차단 및 URL 필터링 시스템에서 URL 접속을 차단할 수 있는 페이지 리다이렉션 기술을 소개한다. 미러링(Mirroring: Out of Path) 환경에서 URL 패킷을 차단하기 위해서 많이 사용하고 있는 방법으로는 RST (Reset) 패킷을 전송하여 세션을 종료하는 방법이다. 이 방법은 요청 서버에 RST(Reset) 패킷을 보내 강제로 종료하는 방식이기 때문에 사용자에게 접근 차단과 관련된 상태 등의 정보를 알려줄 수 없다. 현재 인라인(In-line) 방식에서 사용되고 있는 페이지 리다이렉션 기술을 미러링 환경에서 구현하여 사용자에게 차단 정보를 보여줄 수 있으며 다양한 장비 개발 환경에서 유용하게 사용할 수 있는 기술이라고 판단한다.

• Transactions of the Society of Information Storage Systems
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• v.6 no.2
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• pp.41-46
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• 2010

Recently, Flash Memory Drives are one of the best media to support portable and desktop computers' storage devices. Their features include non-volatility, low power consumption, and fast access time for read operations, which are sufficient to present flash memories as major database storage components for desktop and server computers. However, we need to improve traditional storage management schemes based on HDD(Hard Disk Drive) and RAID(Redundant Array of Independent Disks) due to the relatively slow or freezing characteristics of write operations of SSDs, as compared to fast read operations. In order to achieve this goal, we propose a new storage management scheme called Hetero-Mirroring based on traditional HDD mirroring scheme. Hetero-Mirroring-based storage management improves RAID-1 operation performance by balancing write-workloads and delaying write operations to avoid SSD freezing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.3
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• pp.127-139
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• 2014

In this paper, we present two signal processing techniques for designing binary error correction codes for Multi-Level Cell(MLC) NAND flash memory. MLC NAND flash memory saves the non-binary symbol at each cell and shows asymmetric channel LLR l-density which makes it difficult to design soft-decision binary error correction codes such as LDPC codes and Polar codes. Therefore, we apply density mirroring and EM algorithm for approximating the MLC NAND flash memory channel to the binary-input memoryless channel. The density mirroring processes channel LLRs to satisfy roughly all-zero codeword assumption, and then EM algorithm is applied to l-density after density mirroring for approximating it to mixture of symmetric Gaussian densities. These two signal processing techniques make it possible to use conventional code design algorithms, such as density evolution and EXIT chart, for MLC NAND flash memory channel.