• 대한수학회지
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• 제56권2호
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• pp.289-309
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• 2019

This paper is intended as a discussion of some generalizations of the notion of a reversible ring, which may be obtained by the restriction of the zero commutative property from the whole ring to some of its subsets. By the INCZ property we will mean the commutativity of idempotent elements of a ring with its nilpotent elements at zero, and by ICZ property we will mean the commutativity of idempotent elements of a ring at zero. We will prove that the INCZ property is equivalent to the abelianity even for nonunital rings. Thus the INCZ property implies the ICZ property. Under the assumption on the existence of unit, also the ICZ property implies the INCZ property. As we will see, in the case of nonunital rings, there are a few classes of rings separating the class of INCZ rings from the class of ICZ rings. We will prove that the classes of rings, that will be discussed in this note, are closed under extending to the rings of polynomials and formal power series.

• 한국정보전자통신기술학회논문지
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• 제8권4호
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• pp.257-262
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• 2015

본 논문에서는 SRR-DGS 공진기를 제안하고 그것의 등가회로를 해석하여 저역통과 필터 설계에 적용하였다. 기존의 덤벨형 DGS 구조로 된 것과 비교하였을 때 제안된 구조는 차단주파수 근처에서 스커트 특성과 저주파 대역의 평탄도 특성이 우수하였다. 기본적인 SRR-DGS 셀에서 등가회로의 병렬 커패시턴스를 증가하기 위해 전송선로에 개방 스터브를 추가함으로써 대역외 고주파 억압 특성을 개선하였다. 이와 같은 등가회로의 해석적인 방법으로 개선된 SRR-DGS 셀의 특성이 연구되어 차단 특성이 우수하고 고주파 억압 특성이 35dB이상인 저역통과 필터의 설계에 적용되었다. 그리고 공진기의 측면 길이와 링 간격 등과 같은 물리적 크기와 전송특성과의 관계를 해석하여 나타내었다. 개방 스터브의 면적을 증가하면 차단 주파수 이상의 대역에서 억압 특성이 개선되었다. SRR-DGS에 대해 유도해낸 등가 파라미터와 회로의 정확성을 검증하기 위해 SRR-DGS셀을 이용한 저역통과 필터를 설계하고 제작하였다.

• 대한수학회논문집
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• 제20권3호
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• pp.457-466
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• 2005

We study in this note rings whose prime radicals are completely prime. We obtain equivalent conditions to the complete 2-primal-ness and observe properties of completely 2-primal rings, finding examples and counterexamples to the situations that occur naturally in the process.

• 대한수학회논문집
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• 제11권4호
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• pp.887-893
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• 1996

Let (R,m) be a Cohen-Macaulay local ring with an infinite residue field and let $J = (a_1, \cdots, a_l)$ be a minimal reduction of an equimultiple ideal I of R. In this paper we shall prove that the following conditions are equivalent: (1) $I^2 = JI$. (2) $gr_I(R)/mgr_I(R)$ is Cohen-Macaulay with minimal multiplicity at its maximal homogeneous ideal N. (3) $N^2 = (a'_1, \cdots, a'_l)N$, where $a'_i$ denotes the images of $a_i$ in I/mI for $i = 1, \cdots, l$.

• 대한수학회보
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• 제48권1호
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• pp.23-33
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• 2011

Extending the notion of McCoy rings, we introduce the class of McCoy modules. Over a given ring R, it contains the class of Armendariz modules (over R). Some properties of this class of modules are established, and equivalent conditions for McCoy modules are given. Moreover, we study the relationship between a module and its polynomial module. Several known results relating to McCoy rings can be obtained as corollaries of our results.

• 대한수학회지
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• 제39권1호
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• pp.127-135
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• 2002

Let I be an ideal in a Gorenstein local ring A with the maximal ideal m. Then we say that I is an equimultiple good ideal in A, if I contains a reduction Q = ( $a_1$, $a_2$,ㆍㆍㆍ, $a_{s}$ ) generated by s elements in A and G(I) =(equation omitted)$_{n 0}$ $I^{n}$ / $I^{n＋1}$ of I is a Gorenstein ring with a(G(I)) = 1 - s, where s = h $t_{A}$ I and a(G(I)) denotes the a-invariant of G(I). Let $X_{A}$$^{s}$ denote the set of equimultiple good ideals I in A with h $t_{A}$ I = s, R(I) = A [It] be the Rees algebra of I, and $K_{R(I)}$ denote the canonical module of R(I). Let a I such that $I^{n＋l}$ = a $I^{n}$ for some n$\geq$0 and $\mu$$_{A}$(I)$\geq$2, where $\mu$$_{A}$(I) denotes the number of elements in a minimal system of generators of I. Assume that A/I is a Cohen-Macaulay ring. We show that the following conditions are equivalent. (1) $K_{R(I)}$(equation omitted)R(I)＋as graded R(I)-modules. (2) $I^2$ = aI and aA : I$\in$ $X^1$$_{A}$._{A}$./.

• Kyungpook Mathematical Journal
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• 제55권4호
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• pp.871-883
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• 2015

This paper is devoted to study the divisorial submodules. We get some equivalent conditions for a submodule to be a divisorial submodule. Also we get equivalent conditions for $(N{\cap}L)^{-1}$ to be a ring, where N, L are submodules of a module M.

• 한국가스학회지
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• 제16권6호
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• pp.67-72
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• 2012

본 연구에서는 압축천연가스 자동차용으로 사용하는 CNG 충전니플의 밀봉성과 밀봉내구 안전성에 관련된 접촉법선응력 및 등가진응력을 유한요소법으로 해석하였다. 기존의 원형 오링과 새로운 더블립 오링에 초기압축률 15%를 가한 상태에서 밀봉력을 해석한 결과에 의하면, 두 곳에서 밀봉작용을 하는 더블립 오링이 한곳에서 밀봉작용을 하는 기존의 원형 오링보다 41% 더 높게 나타남을 알 수 있다. 오링에 초기압축력 15%와 가스압축압력 8MPa을 작용한 상태에서 가스누출 차단 안전성을 비교하면, 기존의 원형 오링보다는 더블립 오링에서 5% 향상된 해석결과를 제시하고 있다. 또한, 오링의 밀봉내구 안전성을 비교한 FEM 해석결과에 의하면, 원형 오링보다는 더블립 오링에서 발생된 최대등가진응력이 10.2%나 더 높게 발생한 것으로 나타났다. 이것은 더블립 오링이 기존의 원형 오링보다는 장수명을 보장할 수 있다는 것이다.

• 전기학회논문지
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• 제66권4호
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• pp.629-635
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• 2017

Free-Flooded Ring (FFR) transducer array for use in Sonar system can be driven with large amplitude in a wide frequency band due to its structural characteristics, in which two resonances of a ring mode (1st radial mode) and an inner cavity vibration mode occur in a low frequency band. Since its sound wave generation characteristics are not influenced by the water pressure, the FFR transducer array is widely used in the deep sea. So FFR has been recognized as a low-frequency active sound source and has received much attention ever since. In order to utilize the FFR transducer array for SONAR systems in military and industrial applications, its equivalent electric circuit model is necessary especially to design the matching circuit between the driving power amplifier and the FFR transducer array. Thus this paper proposes the equivalent electric circuit model of FFR transducer array by using measured values of parameter, and suggest the improved method of parameter identification. Finally it verifies the effectiveness of the proposed circuit model of FFR transducer array by experimental measurements.

• 대한수학회보
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• 제39권3호
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• pp.479-484
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• 2002

Let I be an ideal in a Gorenstein local ring A with the maximal ideal m and d = dim A. Then we say that I is a good ideal in A, if I contains a reduction $Q=(a_1,a_2,...,a_d)$ generated by d elements in A and $G(I)=\bigoplus_{n\geq0}I^n/I^{n+1}$ of I is a Gorenstein ring with a(G(I)) = 1-d, where a(G(I)) denotes the a-invariant of G(I). Let S = A[Q/a$_1$] and P = mS. In this paper, we show that the following conditions are equivalent. (1) $I^2$ = QI and I = Q:I. (2) $I^2S$ = $a_1$IS and IS = $a_1$S：sIS. (3) $I^2$Sp = $a_1$ISp and ISp = $a_1$Sp ：sp ISp. We denote by $X_A(Q)$ the set of good ideals I in $X_A(Q)$ such that I contains Q as a reduction. As a Corollary of this result, we show that $I\inX_A(Q)\Leftrightarrow\IS_P\inX_{SP}(Qp)$.