• ETRI Journal
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• 제32권2호
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• pp.184-194
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• 2010

Ethernet ring protection (ERP) technology, which is defined in ITU-T Recommendation G.8032, has been developed to provide carrier grade recovery for Ethernet ring networks. However, the filtering database (FDB) flush method adopted in the current ERP standard has the drawback of introducing a large amount of transient traffic overshoot caused by flooded Ethernet frames right after protection switching. This traffic overshooting is especially critical when a ring provides services to a large number of clients. According to our experimental results, the traditional FDB flush requires a link capacity about sixteen times greater than the steady state traffic bandwidth. This paper introduces four flush optimization schemes to resolve this issue and investigates how the proposed schemes deal with the transient traffic overshoot on a multi-ring network under failure conditions. With a network simulator, we evaluate the performance of the proposed schemes and compare them to the conventional FDB flush scheme. Among the proposed methods, the extended FDB advertisement method shows the fastest and most stable protection switching performance.

• 한국기계가공학회지
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• 제19권3호
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• pp.22-28
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• 2020

This paper investigates the effects of retaining ring materials, particularly PPS and PEEK, used in the CMP process, on wafer polishing and ring wear. CMP can be performed using bonded type retaining rings made with PPS or injection molding type retaining rings made with PEEK. In this study, after polishing a wafer with a PPS retaining ring, the average profile height of the wafer was 0.098 ㎛ less than that of the wafer polished with a PEEK retaining ring, implying that PPS retaining rings achieve a higher polishing rate. In addition, the center area of the wafer profile had less deviation and improved flatness after polishing with the PPS ring. These results indicate that a higher polishing rate and smaller profile height deviation can be achieved using retaining rings made with PPS compared to retaining rings made with PEEK. Therefore, with semiconductor circuit patterns becoming finer and wafer sizes becoming larger, the use of PPS in CMP retaining rings can obtain more stable wafer polishing results compared to that of PEEK.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2000년도 암반공학문제의 수치해석(Numerical Analysis in Rock Engineering Problems)
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• pp.63-66
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• 2000

링 시험펀의 크기와 편심에 따른 응력변화를 FLAC으로 분석하였다. 분석 결과 중공의 크기가 일정한 범위에서만 안정된 값을 얻을 수 있었다. 중공의 크기 오차를 줄이기 위한 상대 공반경은 약 0.3이 적절할 것으로 평가되었다. 한편 중공의 관심 오차가 커지면 응력분포가 불균일하게 되어 정확한 인장강도 산정이 어려운 것으로 사료되었다. 적절한 인장강도를 얻기 위해 중공의 편차는 일정한 정도로 한정하여야 할 것으로 생각된다. 편심으로 인한 오차를 10% 이내로 제한하기 위해서는 중공의 중심은 가압방향에 수평한 방향으로 3%, 수직한 방향으로는 10% 이내가 되어야 하는 것으로 분석되었다.

• 터널과지하공간
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• 제10권3호
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• pp.316-319
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• 2000

링 시험편의 크기와 편심에 따른 응력변화를 FLAC으로 분석하였다. 분석 결과 중공의 크기가 일정한 범위에서만 안정된 값을 얻을 수 있었다. 중공의 크기 오차를 줄이기 위한 상대 공반경은 약 0.3이 적절할 것으로 평가되었다. 한편 중공의 편심 오차가 커지면 응력분포가 불균일하게 되어 정확한 인장강도 산정이 어려운 것으로 사료되었다. 적절한 인장강도를 얻기 위해 중공의 편차는 일정한 정도로 한정하여야 할 것으로 생각된다. 편심으로 인한 오차를 10% 이내로 제한하기 위해서는 중공의 중심은 가압방향에 수평한 방향으로 3%, 수직한 방향으로는 10% 이내가 되어야 하는 것으로 분석되었다.

• 산업기술연구
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• 제26권A호
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• pp.95-99
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• 2006

In this paper, we proposed the new wavelength tunable filter for wide tunability of fiber ring laser. The proposed filter consists of the cascaded connection of Fiber Reflection Mach-Zehnder Interferometer and Sagnac filter or of hybrid filter and Fiber Reflection Mach-Zehnder Interferometer. The simulation shows that the continuous tunable range of 50nm can be obtained and that more stable single mode operation of ring laser can be expected due to narrow FWHM. of filter spectrum.

• Kyungpook Mathematical Journal
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• 제57권3호
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• pp.401-417
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• 2017

Ever since their introduction, skew PBW ($Poincar{\acute{e}}$-Birkhoff-Witt) extensions of rings have kept growing in importance, as researchers characterized their properties (such as primeness, Krull and Goldie dimension, homological properties, etc.) in terms of intrinsic properties of the base ring, and studied their relations with other fields of mathematics, as for example quantum mechanics theory. Many rings and algebras arising in quantum mechanics can be interpreted as skew PBW extensions. Our aim in this paper is to study skew PBW extensions of Baer, quasi-Baer, principally projective and principally quasi-Baer rings, in the case when the base ring R is not assumed to be reduced. We just impose some mild compatibleness over the base ring R, and prove that these properties are stable over this kind of extensions.

• Bulletin of the Korean Chemical Society
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• 제15권11호
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• pp.996-1000
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• 1994

Ab initio calculations with various basis sets have been carried out to investigate the geometries and ring inversion barrier of $R_2TiC_3H_6\;and\;R_2TiS_3$, R=Cp and Cl. Optimized geometries of $R_2TiC_3H_6$ showed the four membered ring was planar on Cs symmetry. However, $R_2TiS_3$ complexes were optimized to be stable in the puckered form. The smallest Basis III with STO-3G on Cp ligands gave reasonable results for the calculations of metallocene. The energy barrier for the ring inversion of metallacyclosulfanes, $Cp_2TiS_3$ was computed to be 8.72 kcal/mol at MP2 level. For the Cl system, we reproduced the molecular structure and ring inversion energy with Basis V.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권6호
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• pp.2734-2747
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• 2018

In this study, a novel fractal ring antenna with a compact size of $24{\times}9{\times}0.8mm^3$ was configured using three iterations. Low profile, circular polarization, and measured operating bands (4.5-6.5 GHz) meet specifications of the upper band used in Wi-Fi and WiMAX applications. The antenna featured, stable radiation properties, especially gain and efficiency, in the notched band (92%). In deep, the antenna impedance, reflection coefficients, surface current distribution and circular polarization for the three iterations had been studied to improve the process of antenna design and its radiation characteristics.

• Kyungpook Mathematical Journal
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• 제59권4호
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• pp.603-615
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• 2019

Let R be an associative unital ring with an endomorphism α and α-derivation δ. The constant products of elements in Ore extension rings, when the coefficient ring is reversible, is investigated. We show that if f(x) = ∑ⁿ_i=0 a_ixⁱ and g(x) = ∑^m_j=0 b_jx^j be nonzero elements in Ore extension ring R[x; α, δ] such that g(x)f(x) = c ∈ R, then there exist non-zero elements r, a ∈ R such that rf(x) = ac, when R is an (α, δ)-compatible ring which is reversible. Among applications, we give an exact characterization of the unit elements in R[x; α, δ], when the coeficient ring R is (α, δ)-compatible. Furthermore, it is shown that if R is a weakly 2-primal ring which is (α, δ)-compatible, then J(R[x; α, δ]) = N iℓ(R)[x; α, δ]. Some other applications and examples of rings with this property are given, with an emphasis on certain classes of NI rings. As a consequence we obtain generalizations of the many results in the literature. As the final part of the paper we construct examples of rings that explain the limitations of the results obtained and support our main results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.559-563
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• 1996

Total 215 magnet power supplies are under operation in Pohang Light Source(PLS). Current, voltage and peak power handling capabilities of DC power supply are in the range of 21 to 643V, 45 to 850A and 0.94 to 531KW, respectively. The DC power supplies can be categoriezed as uni-polar and bipolar power. Typical required stability and ripple of uni-polar power supplies are ${\pm}0.005%$ and ${\pm}0.05%$, respectively. The bipolar power supplies should be maintained within ${\pm}0.05%$ stability and ${\pm}0.5%$ ripple. Precise measurement results show that all power supplies meet or exceed the required specifications. The long term operation reliability to be sufficient for a stable operation of the Pohang Light Source.