• Journal of Broadcast Engineering
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• v.1 no.1
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• pp.55-61
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• 1996

We propose an algorithm for video effects of sports broadcasting that informs TV viewers of a sports player's sequential performing forms and locus in detail when gymnastic game such as 'vault' is broadcasted. It records the image sequences while a player is performing, extracts only the player's performing forms from background scenes by a proposed algorithm, superposes them sequentially on a background scene, and broadcasts them with slow speed. This system named as 'Multi-Motion' has ever been used in NHK live broadcasting for 1995 World Gymnastics Championships held in Japan.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.9
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• pp.883-887
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• 2006

In order to attain high-rate deposition of Mn-Zn ferrite thin film for soft magnetic underlayer in perpendicular magnetic recording media, a reactive sputtering using powder-metal targets under the mixture gas of Ar and $O_{2}$ was performed. It was succeeded that Mn-Zn ferrite films with (111) crystal orientation were deposited on Pt(111) underlayer without any annealing process. The film revealed 3.4 kG of 4 ${\pi}Ms$, 70 Oe of coercivity. The deposition rate of the new method was 16 times as high as that of the conventional method using ferrite target.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.258-259
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• 2003

보호층 0.1mm두께의 20GB이상의 광디스크를 기록·재생하는 High Density Optical System에서는 Blue-violet laser와 NA(Numerical Aperture)0.85의 High NA의 대물렌즈를 사용한 Optical Pick Up이 필요로 된다. 종래의 대물렌즈는 glass 또는 plastic제의 2매 조합 대물렌즈가 많이 사용되어지고 있는데, 이는 두 렌즈간의 거리를 일정하게 유지시키기 위한 홀더 조립시의 공차가 엄격히 요구되며, 2매 조합 대물렌즈를 구동시키기 위한 actuator의 부피와 무게를 증가시킴으로서 구동감도를 감소시키는 단점이 있다. (중략)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1146-1151
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• 2003

So far the study of near-field optical recording(NFR) suspensions has not been investigated sufficiently. In this study the optimization of a NFR suspension is performed using finite element method. NFR suspensions are required to have low compliance modes to allow the slider to comply with the rotating disk, and high tracking stiffness modes to maximize the servo bandwidth of the tracking controller First of all, a basic integrated type suspension model is obtained using topology optimization And the parametric study on the sensitivities of the compliance modes and tracking stiffness modes is performed. Finally, a model satisfying static characteristics is elected and shape optimization is performed to improve dynamic characteristics.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06b
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• pp.310-314
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• 2007

Log-Structured File system은 쓰기에 최적화한 파일 시스템으로 변경된 데이터를 최대한 모아서 순차적으로 기록하는 방식을 가지고 있다. 그러나 실제 시스템에서는 주기적인 동기화로 인해 작은 크기의 데이터들이 디스크로 쓰여지게 되면서 원래의 디자인 목표를 살리지 못하게 된다. 본 연구에서는 최근 급속도로 발전하고 있는 비휘발성 메모리(NVRAM)를 이용해서 주기적인 동기화를 없애고 작은 단위의 쓰기는 NVRAM을 통해 흡수하도록 하였다. 이를 통하여 DRAM만 있는 LFS에 비해 33% 가량 TPC-C 수행 성능이 향상되고, 더 빠르고 고른 응답 시간을 보일 수 있었다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.376-378
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• 2004

리눅스에서는 시스템상의 문제와 보안상의 이유로 특정 파일에 로그를 기록하게 된다. 이 로그파일을 보고 시스템의 문제를 진단하고 시스템을 효과적으로 관리할 수 있다. 또한 이것은 시스템을 안전하게 지키기 위한 도구가 될 수 있다. 그러나 이러한 로그파일은 항상 백업이 필요한 방대한 양의 로그를 지니고 있어 않은 양의 디스크 공간을 차지하고 있으며, 혹시 무슨 일이 있을지 몰라 정기적으로 남기고는 있는데 무슨 내용이 담겨 있는지 의미를 제대로 이해하지 못해 별 도움이 안될 뿐만 아니라, 분석하기도 쉽지 않은 어려움이 있다. 이에 본 논문에서는 보다 효과적으로 리눅스 시스템의 로그파일을 분석 가능하며, 전문가가 아닌 초급 시스템 관리자들도 충분히 이해할 수 있는 리눅스 시스템 로그 분석기를 설계 및 구현 해 보았다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.586-591
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• 2001

Dynamic analysis using impulse responses is formulated to estimate effect of slider rail shape on dynamic responses. Impulse responses are obtained on numerical nonlinear model including rigid motion of slider and fluid motion of air bearing under the slider. Dynamic characteristics of slider motion are evaluated by utilizing the decay ratio of impulse responses and modal frequencies from frequency response functions. The dynamic characteristics of the developed NFR(Near Field Recording) slider are checked by comparing those of HDD sider(Nutcracker). Also, sensitivities of slider position conditions and rotation speed on the dynamic characteristics are investigated. The researches show that the utilized method is a good indicator of designing the better slider.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.89-92
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• 2001

본 논문에서는 공간 데이터베이스 시스템의 공간 데이터 크기에 의한 선별적 회복 기법을 제안하고자 한다. 기존의 대용량 데이터베이스를 위한 회복 관리 기법에는 쉐도우 기법과 변형된 로그 기법이 쓰여지고 있다. 쉐도우 기법은 물리적 응집과 잠금 경쟁 문제가 있으며, 변형된 로그 기법은 공간 데이터의 가변 크기 특성에 대한 고려가 없기 때문에 디스크 입출력이 빈번히 발생하는 문제가 있다. 본 논문에서 제안하는 회복 기법은 공간데이터 크기에 따라 각각 다른 회복 기법을 적용하여, 로그 파일에 기록되는 로그의 양을 줄이며, 또한 트랜잭션 철회시 회복 연산으로 인한 시스템의 부하를 줄이는 장점을 갖는다.

• 한국해양학회지
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• v.27 no.1
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• pp.19-34
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• 1992

Marine seismic refraction surveys have been carried out by Korea Institute of Geology, Mining and Materials(KIGAM) since 1984. The recording of refraction data was based on analog instrumentation. Therefore the resolution of refraction data was not good enough to distinguish many layers. The objective of the interpretation of seismic refraction data is the determination of intervals and critically refracted seismic wave propagation velocities through the layers beneath the sea floor. To determine intervals and velocities precisely, the resolution of refraction data should be enhanced. The intent of the study is to improve the quality of shallow marine refraction data by the digital technique using microcomputer- based acquisition and processing system. The system consists of an IBM AT microcomputer clone, an analog-digital(A/D) converter. A mass storage unit and a parallel processing board. The A/D converter has 12 bits of precision and 250 kHz of conversion rate. The magneto-optical disk drive is used for the mass storage of seismic refraction data. Shallow marine seismic refraction surveys have been carried out using the system at 6 locations off Ulsan and Pusan area. The refraction data were acquired by the radio sonobuoy. The refraction profiles have been produced by the laser printer with 300 dpi resolution after the basic computer processing. 5-9 layers were interpreted from digital refraction profiles, whereas 2-4 layers were interpreted from analog refraction profiles. the propagation velocities of sediments were interpreted as 1.6-2.1 km/sec. The propagation velocities of acoustic basement were interpreted as 2.4-2.7 km/sec off Ulsan area, 4.8 km/sec off Pusan area.

• Journal of KIISE:Databases
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• v.36 no.5
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• pp.374-385
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• 2009

Flash memory becomes increasingly popular as data storage for various devices because of its versatile features such as non-volatility, light weight, low power consumption, and shock resistance. Flash memory, however, has some distinct characteristics that make today's disk-based database technology unsuitable, such as no in-place update and the asymmetric speed of read and write operations. As a result, most traditional disk-based database systems may not provide the best attainable performance on flash memory. To maximize the database performance on flash memory, some approaches have been proposed where only the changes made to the database, i.e., logs, are written to another empty place that has born erased in advance. In this paper, we propose an efficient log management scheme for flash-based database systems. Unlike the previous approaches, the proposed approach stores logs in specially allocated blocks, called log blocks. By evenly distributing logs across log blocks, the proposed approach can significantly reduce the number of write and erase operations. Our performance evaluation shows that the proposed approaches can improve the overall system performance by reducing the number of write and erase operation compared to the previous ones.