• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.3
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• pp.225-235
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• 2013

Cutter forces acting on a disc cutter in TBM are the key parameters for TBM design and its performance prediction. This study aimed to experimentally evaluate cutter forces with different ring shapes in a hard rock. The stiffness of a cutter ring was indirectly estimated from a series of full-scale linear cutting tests. From the experiments, it was verified that the rolling stress acting on a V-shape disc cutter was much higher than on a CCS disc cutter even though the penetration depth by a V-shape disc cutter could be increased in the same cutting condition. Finally, it is suggested that a prediction model considering the shape parameters of a disc cutter should be used for its better prediction.

• Communications of the Korean Mathematical Society
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• v.35 no.4
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• pp.1095-1106
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• 2020

The purpose of this paper is to introduce a new class of rings that is closely related to the class of pseudo-Krull domains. Let 𝓗 = {R | R is a commutative ring and Nil(R) is a divided prime ideal of R}. Let R ∈ 𝓗 be a ring with total quotient ring T(R) and define 𝜙 : T(R) → R_Nil(R) by ${\phi}({\frac{a}{b}})={\frac{a}{b}}$ for any a ∈ R and any regular element b of R. Then 𝜙 is a ring homomorphism from T(R) into R_Nil(R) and 𝜙 restricted to R is also a ring homomorphism from R into R_Nil(R) given by ${\phi}(x)={\frac{x}{1}}$ for every x ∈ R. We say that R is a 𝜙-pseudo-Krull ring if 𝜙(R) = ∩ R_i, where each R_i is a nonnil-Noetherian 𝜙-pseudo valuation overring of 𝜙(R) and for every non-nilpotent element x ∈ R, 𝜙(x) is a unit in all but finitely many R_i. We show that the theories of 𝜙-pseudo Krull rings resemble those of pseudo-Krull domains.

• Bulletin of the Korean Mathematical Society
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• v.52 no.4
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• pp.1353-1363
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• 2015

Let D be a division ring and w($x_1,\;x_2,\;{\ldots},\;x_m$) be a generalized group monomial over $D^*$. In this paper, we investigate subnormal subgroups and maximal subgroups of $D^*$ which satisfy the identity $w(x_1,\;x_2,\;{\ldots},\;x_m)=1$.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.5
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• pp.81-87
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• 1994

This paper proposes a divider structure that combines a carry-propagation-free division algorithm using RSD number system and a self-timed ring structure. The self-timed ring structure enables the divider to compute at a speed comparable to that of combinational array dividers with less silicon area. By exploiting the carry-propagation-free division algorithm, we can achieve further reduction of silicon area and computation time. The algorithm and structure of the proposed divider have been successfully verified through VHDL modeling and simulation. Preliminary experimental results show the effectiveness of the algorithm and structure.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.604-607
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• 2003

Three ring type LC compounds substituted with isothiocyanato group and fluoro atoms in phenyl ring were synthesized, and blended with KL-series LC mixtures for TV application of TN and IPS-mode. Clearing temperature of new LC mixtures are shown $10{\sim}35{\square}$ higher than commercial mixtures. And response time was also improved $10{\sim}20%$ faster than conventional LC mixtures.

• Bulletin of the Korean Mathematical Society
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• v.56 no.4
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• pp.939-959
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• 2019

Using generalized graded crossed products, we give necessary and sufficient conditions for a simple algebra over a Henselian valued field (under some hypotheses) to have Kummer subfields. This study generalizes some known works. We also study many properties of generalized graded crossed products and conditions for embedding a graded simple algebra into a matrix algebra of a graded division ring.

• East Asian mathematical journal
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• v.36 no.1
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• pp.73-79
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• 2020

A ring R is called generalized regular if for every nonzero x in R there exists y in R such that xy is a nonzero idempotent. In this paper, we observe some equivalent conditions for the generalized regular rings that are abelian in terms of idempotents, and we also investigate the primitivity of an idempotent for such a ring. By using the investigation, we characterize such a kind of rings that are noetherian by showing that an abelian generalized regular ring R is noetherian if and only if R is isomorphic to a direct product of finitely many division rings. We also observe some interesting consequences of our results.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.17-20
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• 1999

In these days, wavelength division multiplexing(WDM) all-optical network are being deployed to support various multimedia communication services. In this paper, various WDM all-optical network are discussed, and a design of an all-optical backbone network has been proposed by using multiple self-healing ring technology. The proposed multiple self-healing ring network improves network expandability and efficiency of bandwidth, while it retains simplicity and ease of network control, which are from the nature self-healing ring. Using PDI traffic modeling technique, a well-balanced all-optical backbone network using multiple self-healing ring is designed for the 2010s in Korea.

• Journal of the Optical Society of Korea
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• v.14 no.1
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• pp.38-41
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• 2010

We design and fabricate a widely tunable laser diode made of InGaAsP-InP. The diode is monolithically integrated with a wavelength-selective coupled-ring reflector and semiconductor amplifiers. For realization of a compact size device, deeply etched multi-mode interference couplers and square ring resonators composed of total-internal-reflection mirrors are adopted and fabricated using a self-aligned process. It is demonstrated that the laser diode exhibits single mode operation and 16 nm tuning range with side-mode-suppression-ratio exceeding 20 dB.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.50-52
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• 2022

Brownish rings (BRs) with white interiors are formed during the manufacture of silicon ingots in quartz glass crucibles. These BRs inhibit the yield of silicon ingots. However, the composition and mechanism of the formation of these BRs remain unclear thus far. Therefore, in this study, we analyzed the color and shape of these BRs. Raman analysis revealed that the brown and white colors appear owing to oxygen deficiency rather than crystallization from excess oxygen supply as previously assumed. Moreover, the dark shade of the brown areas depends on the degree of oxygen deficiency and the asymmetrical width of the brown areas is attributed to the direction of the molten silicon flow, which is influenced by the rotation and heat of the ingot crucible.