• 한국광학회:학술대회논문집
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• 한국광학회 2007년도 하계학술발표회 논문집
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• pp.295-296
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• 2007

• 한국정보과학회논문지:시스템및이론
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• 제26권11호
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• pp.1305-1317
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• 1999

NUMA 구조는 원격 메모리에 대한 접근이 불가피한 구조적 특성 때문에 상호 연결망이 성능을 좌우하는 큰 변수가 된다. 기존에 대중적으로 사용되던 버스는 물리적 확장성 및 대역폭에서 대규모 시스템을 구성하는 데 한계를 보인다. 이를 대체하는 고속의 지점간 링크를 사용한 링 구조는 버스가 가지는 확장성 및 대역폭의 한계라는 단점을 개선하였으나, 많은 클러스터가 연결되는 경우에는 전송 지연시간이 증가하는 문제점을 가지고 있다. 본 논문에서는 스누핑 프로토콜이 적용된 링 구조에서 클러스터 개수 증가에 따른 지연시간 증가의 문제점을 보완하기 위해 계층적 링 구조로의 확장을 제안하고, 이 구조에 효과적인 캐쉬 일관성 프로토콜을 설계하였다. 전역 링과 지역 링을 연결하는 브리지는 캐쉬 프로토콜을 관리하며 이 프로토콜에 의해 지역 링의 부하를 줄일 수 있도록 트랜잭션을 필터링하는 역할도 담당함으로써 시스템의 성능을 향상시킨다. probability-driven 시뮬레이터를 통해 계층적 링 구조가 시스템의 성능 및 링 이용률에 미치는 영향을 알아본다. Abstract Since NUMA architecture has to access remote memory, interconnection network performance determines performance of NUMA architecture. Bus, which has been used as popular interconnection network of NUMA, has a limit to build a large-scale system because of limited physical scalability and bandwidth. Ring interconnection network, composed of high-speed point-to-point link, made up for bus's defects of scalability and bandwidth. But, it also has problem of increasing delay as the number of clusters is increased. In this paper, we propose a hierarchical expansion of snoop-based ring architecture in order to overcome ring's defects of increasing delay. And we also design an efficient cache coherence protocol adopted to this architecture. Bridge, which connects local ring and global ring, maintains cache coherence protocol and does snoop-filtering which reduces local ring and cluster bus utilization. Therefore bridge can improve performance of this system. We analyze effects of hierarchical architecture on the performance of system and utilization of point-to-point links using probability-driven simulator.

• 한국정보과학회논문지:데이타베이스
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• 제30권1호
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• pp.52-63
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• 2003

현실 세계에서 시간에 따라 연속적으로 위치나 모양이 변하며 이동하는 데이타를 시공간 이동 객체라 한다. 기존의 이동 객체 색인은 R-트리의 구조를 가지기 때문에, dead spare, overlap 등 R-트리의 문제점을 그대로 갖고 있을 뿐만 아니라 고려하는 초점에 따라 이 문제가 더 커진다. 따라서, 이 논문에서는 이 문제점을 해결하기 위하여 MPR-트리(Moving Point R-tree)를 제안한다. 제안된 MPR-트리는 추출 연산을 활용하여 특정 시점 질의 및 시공간 범위 질의를 효과적으로 처리하며, 동일한 이동 객체 위치를 시간에 따라 연결리스트로 연결하여 궤적 질의 처리를 용이하게 처리한다. 기존 이동 객체 색인과 비교한 실험으로부터 이동 객체 질의 처리 및 공간 활용에 대해 추출 연산이 유용하게 산임을 확인하였다. 제안된 MPR-트리는 LBS, GPS를 활용한 차량 관리 시스템, 항법 시스템 등 이동 객체 관리를 위한 시스템에서 활용될 수 있다.

• 한국기계가공학회지
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• 제2권4호
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• pp.17-24
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• 2003

Chemical mechanical polishing(CMP) has been applied for planarization of topography after patterning process in semiconductor fabrication process. Tungsten CMP is necessary to build up interconnects of semiconductor device. But the tungsten dishing and the oxide erosion defects appear at end-point during tungsten CMP. It has been known that the generation of dishing and erosion is based on the over-polishing time, which is determined by pattern selectivity. Fixed abrasive pad takes advantage of decreasing the defects resulting flam reducing pattern selectivity because of the lower abrasive concentration. The manufacturing technique of fixed abrasive pad using hydrophilic polymers is introduced in this paper. For application to tungsten CMP, chemicals composed of oxidizer, catalyst, and acid were developed. In comparison of the general pad and slurry for tungsten CMP, the fixed abrasive pad and the chemicals resulted in appropriate performance in point of removal rate, uniformity, material selectivity and roughness.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.160-162
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• 2003

ZnO epilayer were synthesized by the pulesd laser deposition(PLD) process on $Al_2O_3$ substrate after irradiating the surface of the ZnO sintered pellet by the ArF(193nm) excimer laser. The substrate temperatures was $400^{\circ}C$. The crystalline structure of epilayer was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of ZnO epilayer measured with Hall effect by van der Pauw method are $8.27{\times}10^{16}\;cm^{-3}\;and\;299\;cm^2V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the ZnO obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;3.3973\;eV\;-\;(2.69{\times}10^{-4}\;eV/K)T^2/(T\;+\;463K)$. After the as-grown ZnO epilayer was annealed in Zn atmospheres, oxygen and vaccum the origin of point defects of ZnO atmospheres has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{Zn}$, Vo, $Zn_{int}$, and $O_{int}$ obtained by PL measurements were classified as a donors or accepters type.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.154-154
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• 2003

A stoichiometric mixture of evaporating materials for CuGaSe2 single crystal thin films was prepared from horizontal electric furnace. Using extrapolation method of X-ray diffraction patterns for the polycrystal CuGaSe2, it was found tetragonal structure whose lattice constant at and co were 5.615 ${\AA}$ and 11.025 ${\AA}$, respectively. To obtain the single crystal thin films, CuGaSe2 mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (MWE) system. The source and substrate temperatures were Slot and 450$^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (UXD). The carrier density and mobility of CuGaSe2 single crystal thin films measured with Hall effect by van der Pauw method are 5.0l${\times}$10$\^$17/ cm$\^$-3/ and 245 $\textrm{cm}^2$/V$.$s at 293K, respectively. The temperature dependence of the energy band gap of the CuGaSe2 obtained from the absorption spectra was well described by the Varshni's relation, Eg(T) = 1.7998 eV - (8.7489${\times}$10$\^$-4/ eV/K)T$^2$/(T + 335 K. After the as-grown CuGaSe2 single crystal thin films was annealed in Cu-, Se-, and Ca-atmospheres, the origin of point defects of CuGaSe2 single crystal thin films has been investigated by the photoluminescence(PL) at 10 K The native defects of V$\_$CU/, V$\_$Se/, Cu$\_$int/, and Se$\_$int/ obtained by PL measurements were classified as a donors or accepters type. And we concluded that the heat-treatment in the Cu-atmosphere converted CuGaSe2 single crystal thin films to an optical n-type. Also, we confirmed that Ga in CuGaSe2/GaAs did not form the native defects because Ga in CuGaSe2 single crystal thin films existed in the form of stable bonds.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권7호
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• pp.2414-2434
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• 2015

Among numerous localization schemes proposed specifically for Wireless Sensor Network (WSN), the range-free localization algorithms based on the received signal strength indication (RSSI) have attracted considerable research interest for their simplicity and low cost. As a typical range-free algorithm, Approximate Point In Triangulation test (APIT) suffers from significant estimation errors due to its theoretical defects and RSSI inaccuracy. To address these problems, a novel localization method called FIAPIT, which is a combination of an improved APIT (IAPIT) and a fuzzy logic system, is proposed. The proposed IAPIT addresses the theoretical defects of APIT in near (it's defined as a point adjacent to a sensor is closer to three vertexes of a triangle area where the sensor resides simultaneously) and far (the opposite case of the near case) cases partly. To compensate for negative effects of RSSI inaccuracy, a fuzzy system, whose logic inference is based on IAPIT, is applied. Finally, the sensor's coordinates are estimated as the weighted average of centers of gravity (COGs) of triangles' intersection areas. Each COG has a different weight inferred by FIAPIT. Numerical simulations were performed to compare four algorithms with varying system parameters. The results show that IAPIT corrects the defects of APIT when adjacent nodes are enough, and FIAPIT is better than others when RSSI is inaccuracy.

• 한국재료학회지
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• 제14권11호
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• pp.755-763
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• 2004

A stoichiometric mixture of evaporating materials for $CuInse_2$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $CuInse_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $620^{\circ}C\;and\;410^{\circ}C$, respectively. The temperature dependence of the energy band gap of the $CuInse_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_{g}(T)=1.1851 eV - (8.99{\times}10^{-4} eV/K)T^2/(T+153 K)$. After the aa-grown $CuInse_2$ single crystal thin films was annealed in Cu-, Se-, and In-atmospheres, the origin of point defects of $CuInse_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{cu},\;V_{Se},\;Cu_{int},\;and\;Se_{int}$ obtained by PL measurements were classified as a donors or accepters type. And we concluded that the heat-treatment in the Cu-atmosphere converted $CuInse_2$ single crystal thin films to an optical n-type. Also, we confirmed that In in $CuInse_2$/GaAs did not form the native defects because In in $CuInse_2$ single crystal thin films existed in the form of stable bonds.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1999년도 PROCEEDINGS OF 99 INTERNATIONAL CONFERENCE OF THE KACG AND 6TH KOREA·JAPAN EMG SYMPOSIUM (ELECTRONIC MATERIALS GROWTH SYMPOSIUM), HANYANG UNIVERSITY, SEOUL, 06월 09일 JUNE 1999
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• pp.187-207
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• 1999

The thermal distributions near the growth interface of 150mm CZ crystals were measured by three thermocouples installed at the center, middle (half radius) and edge (10m from surface) of the crystals. The results show that larger growth rates produced smaller thermal gradients. This contradicts the widely used heat flux balance equation. Using this fact, it si confirmed in CZ crystals that the type of point defects created is determined by the value of the thermal gradient (G) near the interface during growth, as already reported for FZ crystals. Although depending on the growth systems the effective lengths of the thermal gradient for defect generation are varied, were defined the effective length as 10mm from the interface in this experiment. If the G is roughly smaller than 20C/cm, vacancy rich CZ crystals are produced. If G is larger than 25C/cm, the species of point defects changes dramatically from vacancies to interstitial. The experimental results which FZ and CZ crystals are detached from the melt show that growth interfaces are filled with vacancy. We propose that large G produces shrunk lattice spacing and in order to relax such lattice excess interstitial are necessary. Such interstitial recombine with vacancies which were generated at the growth interface, next occupy interstitial sites and residuals aggregate themselves to make stacking faults and dislocation loops during cooling. The shape of the growth interface is also determined by the distributions of G across the interface. That is, the small G and the large G in the center induce concave and convex interfaces to the melt, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.257-265
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• 2002

A stoichiometric mixture of evaporating materials for AgInS$_2$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, AgInS$_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy(HWE) system. The source and substrate temperatures were 680 $^{\circ}C$ and 410 $^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction(DCXD). The carrier density and mobility of AgInS$_2$ single crystal thin films measured from Hall effect by van der Pauw method are 9.35${\times}$10$\^$16/ cm$\^$-3/ and 294 $\textrm{cm}^2$/V$.$s at 293 K, respectively. From the optical absorption measurement, the temperature dependence of the energy band gap on AgInS$_2$ single crystal thin films was found to be E$\_$g/(T) : 2.1365 eV - (9.89 ${\times}$ 10$\^$-3/ eV) T$^2$/(2930 + T). After the as-grown AgInS$_2$ single crystal thin films was annealed in Ag-, S-, and In-atmospheres, the origin of point defects of AgInS$_2$ single crystal thin films has been investigated by using the photoluminescence(PL) at 10 K. The native defects of V$\_$AG/, V$\_$S/, Ag$\_$int/, and S$\_$int/ obtained from PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the S-atmosphere converted AgInS$_2$ single crystal thin films to an optical p-type. Also, we confirmed that In in AgInS$_2$/GaAs did not form the native defects because In in AgInS$_2$ single crystal thin films did exist in the form of stable bonds.