• 한국수학교육학회지시리즈A:수학교육
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• 제21권1호
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• pp.19-21
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• 1982

In this paper, we define the z-S-closed spaces using the notions of zero-sets and S-closed spaces introduced by T. Thompson, and investigate some properties of these spaces. We also obtain the following results. If a space X is z-S-closed, then every cover of z-regular semiopen sets has a finite proximate subcover. A z-extremally disconnected z-QHC space is z-S-closed, z-S-closed is contagious.

• 호남수학학술지
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• 제42권1호
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• pp.161-173
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• 2020

We introduce statistically localized sequences in 2-normed spaces and give some main properties of statistically localized sequences. Also, we prove that a sequence is statistically Cauchy sequence if and only if its statistical barrier is equal to zero. Moreover, we define the uniformly statistically localized sequences on 2-normed spaces and investigate its relationship with statistically Cauchy sequences.

• Korean Journal of Mathematics
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• 제32권1호
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• pp.97-107
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• 2024

Let A ⊆ B be an extension of integral domains with characteristic zero. Let H(A, B) and h(A, B) be rings of composite Hurwitz series and composite Hurwitz polynomials, respectively. We simply call H(A, B) and h(A, B) composite Hurwitz rings of A and B. In this paper, we study when H(A, B) and h(A, B) are unique factorization domains (resp., GCD-domains, finite factorization domains, bounded factorization domains).

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.313-318
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• 1998

Generally, the concrete constructed during cold weather has the frozen damage which cause the fatal damage so that heat curing and sheet curing was performed to prevent the early freezing of concrete. However, partial refrigeration caused by thermal gradient has many troubles so that the construction hasn`t been done as possible. This paper presents the development of strenth properties and optimal mix design against frozen damage under the cold weather, 1$0^{\circ}C$ below the zero.

• 대한수학회보
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• 제47권2호
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• pp.231-249
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• 2010

Asymptotic behavior of three-dimensional mixed, periodic and rotating magnetohydrodynamic system is investigated as the Rossby number goes to zero. The system presents the difficulty to be singular and mixed, that is hyperbolic in the vertical direction and parabolic in the horizontal one. The divergence free condition and the spectral properties of the penalization operator are crucial in the proofs. The main tools are the energy method, the Schochet's method and products laws in anisotropic Sobolev spaces.

• 대한수학회논문집
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• 제33권3호
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• pp.823-831
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• 2018

We define progressive tax rate functions, study their properties, and describe some smooth models. The key requirement, defining the progressive nature of the taxation model, is that the progressive tax rate functions should have infinite contact with the zero function at the origin, in order to care the poor. In constructing a wide array of such functions, assisting functions are introduced.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.572-577
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• 1992

In this paper, the optimal homing guidance problem is investigated for the general missile/target models described in the state-space. The closed-form solution of the optimal guidance law derived, and its asymptotic properties are studied as the time-to-go goes to infinity or zero. Futhermore, several approximate solutions of the optimal guidance law are suggested for real-time applications.

• 대한수학회논문집
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• 제23권2호
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• pp.161-167
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• 2008

A ring R is called an $I_0$-ring if each left ideal not contained in the Jacobson radical J(R) contains a non-zero idempotent. If, in addition, idempotents can be lifted modulo J(R), R is called an I-ring or a potent ring. We study whether these properties are inherited by some related rings. Also, we investigate the structure of potent rings.

• Bulletin of the Korean Chemical Society
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• 제19권5호
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• pp.575-579
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• 1998

The 77 K luminescence and excitation spectra, and 298 K infrared and absorption spectra of $cis-{\Alpha}-[Cr(trien)Cl_2]Cl{\cdot}H_2O$ (trien=triethylenetetramine) have been measured. Ligand field electronic transitions due to spin-allowed and spin-forbidden are assigned. The zero-phonon line in the excitation spectrum splits into two components by $198\; cm^{-1}$, and the large $^2E_g$ splitting can be reproduced by the modern ligand field theory. It is confirmed that nitrogen atoms of the trien ligand have a strong σ-donor character, but chloride ligand has weak σ- and π -donor properties toward chromium(III) ion.

• Transactions on Electrical and Electronic Materials
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• 제5권3호
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• pp.120-121
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• 2004

YBaCuO thick films were fabricated by plasma enhanced chemical vapor deposition, and the crystallinity and the superconducting properties were investigated. The growth temperature to obtain the thick films was decreased by around 150$^{\circ}C$ due to plasma enhancement. The zero resistivity temperatures for films grown at 590$^{\circ}C$ and 620$^{\circ}C$ were 55 and 80 K, respectively.