• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.205.1-205.1
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• 2012

러시아 발사체 드네프르에 의해 발사될 과학기술위성 3호의 주탑재체 다목적적외선영상시스템, MIRIS (Multipurpose InfraRed Imaging System)는 한국천문연구원에서 주관하여 개발되었다. 그 구성 카메라인 EOC (Earth Observation Camera)는 한반도재난감시를 수행하고, SOC (Space Observation Camera)는 우리 은하 평면의 근적외선 서베이 관측을 통해 $360^{\circ}{\times}6^{\circ}$ Paschen-${\alpha}$ 방출선 지도를 작성하고 I, H 밴드 필터를 이용해서 황도 남북극에 대한 적외선우주배경복사를 관측한다. MIRIS 비행모델이 제작 완료되었고, 그 구성 기기인 SOC, EOC, 전장박스에 대한 최종 우주환경시험을 수행하였다. 과학기술위성 3호의 비행모델 우주환경시험은 진동시험과 열진공시험으로 이뤄지며, 그 시험 규격은 문서에 규정된 Acceptance Level로 수행된다. 충격시험은 공학인증모델을 통해 검증되었다. 열진공시험은 한국천문연구원에서 수행되었으며, 진동시험은 한국과학기술원 인공위성센터에서 수행되었다. 또한 전체 위성이 조립된 후 과학기술위성 3호의 열진공시험은 한국항공우주연구원에서 수행되었다. 이 발표에서는 MIRIS 비행모델에 대한 환경시험과정 및 결과를 보고하고, 과학기술위성이 전체적으로 조립된 후의 MIRIS 진동 및 열진공 시험 결과도 함께 논의한다.

• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.9-14
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• 2009

We calculated tetragonal-$HfO_2$/Si superstructures using density functional theory. When a and b-axes of cubic-$HfO_2$ were increased to be matched with those of Si for epitaxy contact, c-axis was decreased by 2%. Eight models of interface layers were produced by choosing different terminating layers of tetragonal-$HfO_2$ and Si substrate at the interface. It was found that tetragonal-$HfO_2$ $(004)_{1/4}$/Si $(004)_{3/4}$ superstructure was the most favorable and tetragonal-$HfO_2$ (004)$_{1/4}$/Si (002) superstructure was the most unfavorable. In tetragonal-$HfO_2$ $(004)_{1/4}$/Si (002) superstructure, there were two oxygen vacancies in tetragonal-$HfO_2$ as two oxygen atoms were moved to Si substrate located at the interface.

• The KIPS Transactions:PartD
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• v.11D no.5
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• pp.1011-1020
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• 2004

A lot of work has been done to improve the I/O performance of such a system that store and manage a massive amount of data by distributing them across multiple disks and access them in parallel. Most of the previous work has focused on an efficient mapping from a grid ceil, which is determined bY the interval number of each dimension, to a disk number on the assumption that each dimension is split into disjoint intervals such that entire data space is GRID-like partitioned. However, they have ignored the effects of a GRID partitioning scheme on declustering performance. In this paper, we enhance the performance of mapping function based declustering algorithms by applying a good GRID par-titioning method. For this, we propose an estimation model to count the number of grid cells intersected by a range query and apply a GRID partitioning scheme which minimizes query result size among the possible schemes. While it is common to do binary partition for high-dimensional data, we choose less number of dimensions than needed for binary partition and split several times along that dimensions so that we can reduce the number of grid cells touched by a query. Several experimental results show that the proposed estimation model gives accuracy within 0.5% error ratio regardless of query size and dimension. We can also improve the performance of declustering algorithm based on mapping function, called Kronecker Sequence, which has been known to be the best among the mapping functions for high-dimensional data, up to 23 times by applying an efficient GRID partitioning scheme.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2784-2790
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• 2015

The column-oriented database storage is a very advanced model for large-volume data transactions because of its superior I/O performance. Traditional data storages exploit row-oriented storage where the attributes of a record are placed contiguously in hard disk for fast write operations. However, for search-mostly data warehouse systems, column-oriented storage has become a more proper model because of its superior read performance. Recently, solid state drive using flash memory is largely recognized as the preferred storage media for high-speed data analysis systems. In this research, we propose a new transaction recovery scheme for a column-oriented database environment which is based on a flash media file system. We improved traditional shadow paging schemes by reusing old data pages which are supposed to be invalidated in the course of writing a new data page in the flash file system environment. In order to reuse these data pages, we exploit reused shadow list structure in our column-oriented shadow recovery(CoSR) scheme. CoSR scheme minimizes the additional storage overhead for keeping shadow pages and minimizes the I/O performance degradation caused by column data compression of traditional recovery schemes. Based on the results of the performance evaluation, we conclude that CoSR outperforms the traditional schemes by 17%.

• Journal of the Mineralogical Society of Korea
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• v.14 no.1
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• pp.73-84
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• 2001

티타늄과 산소의 함량이 서로 다른 4가지의 합성 페롭스카이트형(perovskite-type) 광물(($K_2$$La_2$$Ti_{n}$/$O_{2n+4}$, n=3, 4, 5, 6; 14/mcm, 14/mmm, I42 m)을 대상으로 리트벨트(Rietveld)구조분석법을 실시하여 결정구조를 밝히고 티타늄함량에 따른 층상형 구조를 연구하였다. 4가지 합성시료에 대하여 구조분석을 실시한결과 대표적인 페롭스카이트형 광물인 토소나이트(taustonite, $La_{1-x}$ //$K_{x}$ /$TiO_3$, x<0.4)가 주성분으로 나타났으며 토스나이트내에 12개의 산소를 배위하는 A자리 양이온은 자리점유율에 의해 $La^{3+}$ 와 $K^{+}$ /의 치환관계를 보여준다 공간군은 14/mcm, 단위포는 a=5.505(1)~5.510(1)$\AA$, c=7.793(1)~7.796(1)$\AA$ V=236.25~236.66 $\AA^3$ 범위의 값을 갖는다. 구조의 정밀도를 나타내는 R지수를 살펴보면 $R_{B}$ 값은 5.31~9.10 S(GofF)값은 0.86~1.24로 각각 계산되었다. 12배위를 하는 A자리 양이온인 란탄과 산소의 평균거리는 2.755$\AA$이고 6배위를 하는 B자리 양이온인 티타늄과 산소의 평균거리는 1.948 $\AA$의 결과를 얻었다. 합성된페롭스카이트형 광물의 층상구조가 알려져 있지 않아 시뮬레이션을 통해 구조모델을 결정하였으며 그결과 n=3인 R-38시료에서만 두 종류의 층상 페롭스카이트($La_2$$K_2$$Ti_3$$O_{10}$ ) 구조 (A-type: 14/mmm, a=3.8178 $\AA$, c=29.9189 $\AA$, V=436.04 $\AA^3$, B-type: 142 m, a =3.8376 $\AA$, c=28.023 $\AA$, V=412.6 $\AA^3$)가 존재함을 확인하였으나 다른 시료에서는 토소나이트, 금홍석 외에 새로운 합성광물로 제파이트의 존재를 확인하였다.

• Journal of the Korean Magnetics Society
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• v.18 no.4
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• pp.154-158
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• 2008

Magnetite($Fe_3O_4$) is currently one of key materials for applications in magnetic storage and many bioinspired applications because bulk $Fe_3O_4$ has a high Curie temperature($Tc={\sim}850K$) and nearly full spin polarization at room temperature(RT). In this work, $Fe_3O_4$ nanoparticles with different sizes of 12 to 15 nm were prepared in a well-controlled manner by a nonhydrolytic synthetic method. Here, we report the significant intergrain magneto-resistance(MR) of ${\sim}2%$ at RT in $Fe_3O_4$ nanoparticle pellets. The tunneling conductance was also investigated based on the Brinkman model, as well. Our results show clearly that the surface or interfacial property of the particles plays a crucial role in the MR effect.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.9
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• pp.916-920
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• 2008

The personal workspace consists of user- specified computing environment such as user profile, applications and their configurations, and user data. Mobile computing devices (i.e., cellular phones, PDAs, laptop computers, and Ultra Mobile PC) are getting smaller and lighter to provide personal work-space ubiquitously. However, various personal work-space mobility solutions (c.f. VMWare Pocket ACE[1], Mojopac[2], u-PC[3], etc.) are appeared with the advance of virtualization technology and portable storage technology. The personal workspace can be loaded at public PC using above solutions. Especially, we proposed a framework called ubiquitous personal computing environment (u-PC) that supports mobility of personal workspace based on wireless iSCSI network storage in our previous work. However, previous u-PC could support limited applications, because it uses IRP (I/O Request Packet) forwarding technique at filter driver level on Windows operating system. In this paper, we implement OS-level virtualization technology using system call hooking on Windows operating system. It supports personal workspace mobility and covers previous u-PC limitation. Also, it overcomes personal workspace loading overhead that is limitation of other solutions (i.e., VMWare Pocket ACE, Mojopac, etc). We implement a prototype consisting of Windows XP-based host PC and Linux-based mobile device connected via WiNET protocol of UWB. We leverage several use~case models of our framework for proving its usability.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.2 s.152
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• pp.83-92
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• 2007

To improve the fire safety of ships, it is required to prepare the systematic design guideline for fire protection and the way of assessing fire characteristics quantitatively. The introduction of simulation technique based on fire engineering is useful to assess fire safety performance quantitatively. Fire simulation tools are currently developing with U.S.A., Europe and Japan as a leader. Most of current fire simulation tools were developed for building or inland structure. Therefore it is required validation process and development of data base to apply maritime environments. In this paper, I/O parameters of simulation tools such as CFAST and BRI2002 of zone model and FDS and KFX of field model analysed, and designed data base considering maritime environment. The fire simulation for the pool fire model of engine room and its adjacent compartments is performed and evaluated the results.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.6
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• pp.42-50
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• 1993

In this paper the affect an inorganic filler and a f i n g up water absorption in epoxy composite material was represented. The results are summarized as follows ; 1. In the case of Sample 1, Sample 2 and a fillng up water absorption, the frequency depenence of E,' shows the straight characteristic underl4O0C. 2. Between lOOHz and 3kHz, the frequency dependency of tan8 is dominated by the loss of a dipole relaxation than the conductive loss for movement of a career. The effect of water absorption, is increased as the frequency is d e creased.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1667-1670
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• 2005

본 논문에서는 차세대 통신 플랫폼을 위한 PCI Express의 전송계층과 데이터 연결계층의 모든 기능을 지원하는 PCI Express 컨트롤러를 설계하였다. 설계되어진 컨트롤러는 재전송 매커니즘을 효과적으로 지원하기 위해 제안되어진 송신버퍼 구조를 가지고 있다. 이 버퍼 구조는 전송 버퍼와 재전송 버퍼를 한 개의 버퍼로 통합하여 재전송 버퍼의 공간을 유동적으로 할당할 수 있는 방법이다. 또한 설계되어진 컨트롤러의 송신단 전송계층은 제안되어진 버퍼 구조 효과적으로 지원하도록 설계되어 졌다. 설계 되어진 컨트롤러의 각 블록을 효과적으로 관리하기 위해 80C51 마이크로프로세서를 내장하여 PCI Express 프로토콜을 제공하는 프로그램을 코딩하여 포팅하였다. 또한 설계되어진 컨트롤러의 검증을 위해, Host Bridge, 로컬 마스터 디바이스, 로컬 슬레이브 디바이스를 버스 동작 모델로 구성된 테스트 벤치도 제안하였다. 또한 실제 PCI Express 프로토콜 상에서 발생할 수 있는 모든 경우를 발생 하도록 하기 위해, 각 버스 동작 모델을 위한 어셈블러 명령어들을 정의 하였다.