• The Journal of Society for e-Business Studies
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• v.14 no.1
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• pp.143-160
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• 2009

In determining the performance of OLAP database applications, the structure and the effective access methods to the underlying disk system is a significant factor. In recent years, hard disks are designed with multiple physical zones where seek times and data transfer rates vary across the zones. However, there is little consideration of multi-zone disks in previous works. Instead, they assumed a traditional disk model that comes with many simplifying assumptions such as an average seek-time and a single data transfer rate. In this paper, we propose a technique storing a set of materialized views into the multi-zoned disks in OLAP environment dealing with large sets of data. We first present the disk zoning algorithm of materialized views according to the access probabilities of each views. Also, we address the problem of storing views in the dynamic environment where data are updated continuously. Finally, through experiments, we prove the performance improvement of the proposed algorithm against the conventional methods.

• Journal of Institute of Convergence Technology
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• v.1 no.2
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• pp.16-24
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• 2011

The angular electrostatic microactuator using skewed electrode array (SEA) scheme was proposed. The moving and fixed electrodes are arranged to make the driving force perpendicular to the rotating moment of arm. By changing the electrode overlap length, the magnitude of electrostatic force and stable displacement will be changed. In order to optimize the design, electrostatic FE analysis were carried out and the empirical force model was established for SEA. Simulation was performed to make the comparison between conventional actuators and SEA. The proposed SEA generates actuating torque 2 times greater than a comb-drive and stable actuator displacement 40% greater than a parallel plate type actuator. The angular electrostatic microactuator using skewed SEA scheme was designed and fabricated using SoG process.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.1
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• pp.60-67
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• 2000

An improved disturbance rejection control scheme is presented for minimizing the position error due to the repeatable runout disturbances in high density disk drive systems The proposed control algorithm is capable of attenuating repeatable disturbances which is one of the major detractors to hard disk drive quality and performance. This is achieved by a sys-tematic combination of an optimal feedback component and a feedforward preview component. The feedback component is designed where the emphasis is placed on robustness. The feedforward component is on the basis of a preview control comprised of a measured disturbance signals which leads to better disturbance rejection capabilites. The designed con-troller is applied as a plug-in module to a high density hard disk drive with a pre-existing conventional servo controller. Simulations have been carried out to demonstrate the effectiveness of this control scheme in the reduction of the periodic disturbances.

• Publications of The Korean Astronomical Society
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• v.5 no.1
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• pp.95-103
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• 1990

일반인에게 널리 보급된 IBM 계열의 16비트 PC(XT, AT)로도 손쉽게 도형출력이 가능한 천문 계산용 포트란 그래픽 라이브러리를 CALCOMP계의 문법에 맞추어 개발하였다. 본 라이브러리를 사용하면 그래픽 어댑터(HGC, CGA, EGA, VGA)에 임의로 대응되는 화면출력과 XY플롯터는 물론이거니와 EPSON계의 9핀 혹은 24핀 도트프린터에 의한 고품질(9핀 프린터; 0.21mm/dot, 24핀 프린터; 0.14mm/dot)의 도형출력이 가능하다. 프린터에 의해 출력 가능한 도형의 크기는 하드디스크의 용량이 허용하고 처리 속도를 인내할 수 있는 한 무한대로 확장할 수 있는데 비교적 빠른 시간 내에 처리할 수 있는 표준 도형 크기로서 최대 작도 범위를 80 컬럼용 프린터 용지 한 페이지 크기인 $25cm{\times}20cm$를 지정하였다.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2429-2431
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• 2004

In this paper, we have designed a remote controlable HDR System using all embedded linux board. The system is composed of three parts - a HDR System, a PC client program for remote control and a Nameserver for registering and aquisition of the IP address. The system is built in an embedded board using a linux kernel. With the Linux the system can support networking and file system for a hard disk management In addition, the system embeds a web-server and a ftp-server for remote manipulation and file transfer. And the hardwares of the system are controlled by the linux device driver mechanism. MPEG1/2 technique is used to compress TV tuner signal and external analog video/audio signal. And compressed data is stored in a hard disk. The data stored in the system is accesable through lan or internet. And RTP protocol is used to enable the system to service live stream of instant video/audio input.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.340.1-340
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• 2002

The unbalance exciting force induced by HDD of lately getting higher speed is directly influenced by the rotational speed and the mechanical assembly allowance between disk and spindle motor, and which gives rise to the structure borne noise of the personal computer. The absolute unbalance mass of HDD needs to be measured and adjusted by the counter mass to control the unbalance exciting force effectively in the stage of assembling the disk and spindle motor. This study introduces the measurement methods of the magnitude of the absolute unbalance mass and the position of HDD by 2 accelerometers. The absolute unbalance mass can be obtained by the acceleration responses and the mobility of the mechanical part, while the position of the unbalance mass can e obtained by the rotation acceleration orbit.

• Review of KIISC
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• v.20 no.1
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• pp.47-55
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• 2010

최근 주요 기업에서 기업 비밀정보가 유출되는 보안사고가 빈번히 발생함에 따라, 기업의 비밀정보 유출 방지 및 보호에 대한 사회적 관심이 높아지고 있다. 기업 비밀정보의 유출은 해당 기업뿐만 아니라 국가적으로도 막대한 손실을 초래할 수 있다는 문제를 가지고 있다. 이러한 문제를 해결하기 위해 각 기업에서는 보호구역의 설정, 출입허가 또는 출입시 휴대품 검사 등의 물리적인 유출 차단 방법을 구축하고 있으며, 기업 기밀문서에 대해서는 DRM(digital right management)을 활용한 문서유출 방지 및 네트워크 트래픽 차단 등 다양한 방법을 적용하고 있다. 하지만, 전자파일 형태로 존재하는 기밀문서는 인터넷 또는 네트워크에 연결된 PC 및 서버를 통해 전자우편(E-mail), 메신저, 게시판 등으로 쉽게 유출될 수 있어 많은 문제점을 가지고 있다. 이러한 시점에서 최근 널리 보급되고 있는 디지털 복합기는 문서 저장을 위한 하드디스크(HDD) 및 네트워크 응용 서비스를 포함하고 있어 다양한 보안 취약점에 노출되어 있다. 따라서 기업 비밀정보 유출 방지와 보호를 위해서는 디지털 복합기에 대한 보안 기술 연구가 필수적이다. 이에 본고에서는 기업 비밀정보 유출 방지 및 보호 관점에서 디지털 복합기 개발 현황을 살펴보고, 보안상 문제점을 해결하기 위해 연구되고 있는 디지털 복합기 보안기술에 대한 동향을 살펴보고자 한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.2
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• pp.201-211
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• 2012

This paper addresses a Full Disk Encryption hardware processor for SATA HDD in a single FPGA design, and shows its experimental result using an FPGA board. The proposed processor mainly consists of two blocks: the first block processes XTS-AES block cipher which is the IEEE P1619 standard of storage media encryption and the second block executes the interface between SATA Host (PC) and Device (HDD). To minimize the performance degradation, we designed the XTS-AES block with the 4-stage pipelined structure which can process a 128-bit block per 4 clock cycles and has 4.8Gbps (max) performance. Also, we implemented the proposed design with Xilinx ML507 FPGA board and our experiment showed 140MB/sec read/write speed in Windows XP 32-bit and a SATA II HDD. This performance is almost equivalent with the speed of the direct SATA connection without FDE devices, hence our proposed processor is very suitable for SATA HDD Full Disk Encryption environments.

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.251-258
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• 2016

Recently, the demand for fast storage devices is rapidly increasing in cloud platforms, social network services, etc. Despite the development of fast storage devices, the traditional Linux I/O stack is not able to exploit the full extent of the performance improvement since it has been optimized for disk-based storage devices. In this paper, we propose an optimized I/O stack which can fully utilize the I/O bandwidth and latency of fast storage devices. To this end, we design a new I/O interface to replace the current block I/O interface and optimize our I/O interface. Our optimized I/O interface bypasses operations/layers in block I/O subsystems of the current Linux I/O stack to fully exploit fast storage devices. We also optimize the Linux file systems such as ext2 and ext4 to run on our I/O interface. We evaluate our I/O stack with multiple benchmarks and the experimental results show that our I/O stack achieves 1.7 times better throughput compared to traditional Linux I/O stack.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.70.2-70.2
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• 2013

한국천문연구원은 일본국립천문대와 한일공동으로 개발한 한일공동VLBI상관기(KJJVC)의 VLBI 관측자들에게 연구결과를 제공할 수 있는 정상운영을 2013년부터 수행하였다. 한일상관센터(KJCC)에서는 평균 8시간정도 관측한 VLBI 관측자료의 상관처리에 소요되는 시간은 약 2주 정도이며, 데이터 분석가의 확인을 거친 후 담당 PI에게 상관결과를 전달하고 있다. 현재 상관처리는 다양한 관측모드 중에서 연구관측에서 많은 비중으로 차지하고 있는 C5(16MHz 대역폭에 16stream) 모드를 지원하고 있으며, 2013년도에 여러 연구자들의 요구에 대응하기 위해 Wideband(512MHz 대역폭), C1(256MHz 대역폭, 1stream), C2(128MHz 대역폭, 2stream) 모드를 지원할 수 있도록 시스템의 성능을 개선할 예정이다. 또한 일본국립천문대에서는 자기테이프를 사용하고 있는 VERA 관측망에 대해 관측자료의 복사시간 단축, 운영효율을 향상시키기 위해 하드디스크를 채용한 OCTADISK 시스템을 개발하였으며, 한일상관센터에도 동기재생처리장치에 장착된 2대의 OCTADDB를 OCTADISK로 수정작업을 추진하였다. 본 보고에서는 이상에 기술한 것과 같이 한일상관센터의 운영현황과 향후 계획에 대해 자세히 기술한다.