• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
• /
• pp.399-401
• /
• 2005

When power cables cross regions with unfavorable thermal conditions, conductor temperatures higher than the design value can occur. This paper proposes the calculation algorithms of the permissible current-carrying capability of dissimilar power cables installed in thermally dissimilar soil materials.

• East Asian mathematical journal
• /
• 제21권1호
• /
• pp.61-64
• /
• 2005

Let R be a commutative ring with identity, and let $f,\;g_i(i=1,\;\ldots,\;n),\;g_{\alpha}(\alpha{\in}S)$ be elements of R. We show that the following statements are equivalent; (i) $X_f{\subseteq}{\cup}_{\alpha{\in}S}X_{g\alpha}$ only if $X_f{\subseteq}X_{g\alpha}$ for some $\alpha{\in}S$, (ii) $V(f){\subseteq}{\cup}_{\alpha{\in}S}V(g_{\alpha})$ only if $V(f){\subseteq}V(g_{\alpha})$ for some $\alpha{\in}S$, (iii) $V(f){\subseteq}{\cup}^n_{i=1}V(g_i)$ only if $V(f){\subseteq}V(g_i)$ for some i, (iv) Spec(R) is linearly ordered under inclusion.

• 대한수학회보
• /
• 제31권1호
• /
• pp.105-113
• /
• 1994

In the course of study of dendroids, Czuba [3] introduced a notion of $R^{i}$ -continua which is a generalization of R-arc [1]. He showed a new class of non-contractible dendroids, namely of dendroids which contain an $R^{i}$ -continuum. Subsecequently Charatonik [2] attempted to extend the notion into hyperspace C(X) of metric continuum X. In so doing, there were some oversights in extending some of the results relating $R^{i}$ -continua of dendroids for metric continua. In fact, Proposition 1 in [2] is false (see example C below) and his proof of Theorem 6 in [2] is not correct (Take Example 4 in [4] with K = [e,e'] as an $R^{1}$-continuum of X and work it out. Then one seens that K not .mem. K as he claimed otherwise.). The aims of this paper are to introduce a notion of w-regular convergence which is weaker than 0-regular convergence and to prove that the w-regular convergence of a sequence {Xn}$^{\infty}$$_{n=1}$ to $X_{0}$ of subcontinua of a metric continuum X is a necessary and sufficient for the sequence {C( $X_{n}$)}$^{\infty}$$_{n=1}$ to converge to C( $X_{0}$ ), and also to prove that if a metric continuum X contains an $R^{i}$ -continuum with w-regular convergence, then the hyperspace C(X) of X contains $R^{i}$ -continuum.inuum.uum.

• 대한수학회보
• /
• 제42권4호
• /
• pp.679-690
• /
• 2005

Let K be a commutative ring with unity, R a prime K-algebra of characteristic different from 2, d a non-zero derivation of R, I a non-zero right ideal of R, f($x_1,{\cdots},\;x_n$) a multilinear polynomial in n non-commuting variables over K, a $\in$ R. Supppose that, for any $x_1,{\cdots},\;x_n\;\in\;I,\;a[d(f(x_1,{\cdots},\;x_n)),\;f(x_1,{\cdots},\;x_n)]$ = 0. If $[f(x_1,{\cdots},\;x_n),\;x_{n+1}]x_{n+2}$ is not an identity for I and $$S_4(I,\;I,\;I,\;I)\;I\;\neq\;0$$, then aI = ad(I) = 0.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 A
• /
• pp.189-191
• /
• 2004

This paper presents summary results of direct interview survey of Korean industrial customers conducted to evaluate the direct and short duration interruption costs resulting from local random electrical supply interruptions. The cost is evaluated using the questionnaires authors designed, which are mainly on the experience or preparatory actions consumers Predicted they would take. Economic evaluation of reliability that traditionally takes into account duration and frequency of interruption does not accurately reflect the lost value or economic impacts of industrial customer, especially large size, caused by any kind of interruption. So, to imply the substantial difference in costs incurred by different customer group, the authors apply the international standards, i.e. IEC, IEEE, to the analysis on the interruption costs.

• 대한수학회보
• /
• 제31권2호
• /
• pp.210-214
• /
• 1994

The purpose of this paper is to investigate the relationship between the depths of the Rees algebra R[It] and the associated graded ring g $r_{I}$(R) of an ideal I in a local ring (R,m) of dim(R) > 0. The relationship between the Cohen-Macaulayness of these two rings has been studied extensively. Let (R, m) be a local ring and I an ideal of R. An ideal J contained in I is called a reduction of I if J $I^{n}$ = $I^{n+1}$ for some integer n.geq.0. A reduction J of I is called a minimal reduction of I. The reduction number of I with respect to J is defined by (Fig.) S. Goto and Y.Shimoda characterized the Cohen-Macaulay property of the Rees algebra of the maximal ideal of a Cohen-Macaulay local ring in terms of the Cohen-Macaulay property of the associated graded ring of the maximal ideal and the reduction number of that maximal ideal. Let us state their theorem.m.m.

• 대한수학회보
• /
• 제51권4호
• /
• pp.1127-1133
• /
• 2014

Let S be a nonempty subset of a ring R. A map $f:R{\rightarrow}R$ is called strong commutativity preserving on S if [f(x), f(y)] = [x, y] for all $x,y{\in}S$, where the symbol [x, y] denotes xy - yx. Bell and Daif proved that if a derivation D of a semiprime ring R is strong commutativity preserving on a nonzero right ideal ${\rho}$ of R, then ${\rho}{\subseteq}Z$, the center of R. Also they proved that if an endomorphism T of a semiprime ring R is strong commutativity preserving on a nonzero two-sided ideal I of R and not identity on the ideal $I{\cup}T^{-1}(I)$, then R contains a nonzero central ideal. This short note shows that the conclusions of Bell and Daif are also true without the additivity of the derivation D and the endomorphism T.

• 정보관리학회지
• /
• 제5권1호
• /
• pp.31-52
• /
• 1988

정보의 자원화를 국가 발전의 기본적인 원동력으로 간주하고 있는 일본의 정책 현 황을 일본학술회의, 과학기술청, 통상산업성, 문부성을 중심으로 분석하였다. 정책이 효과적 으로 실행되기 위하여서는 최고 통치권자를 자문하는 협의 기관이 반드시 필요하며 이를 능 독적으로 활동시키기 위한 제도 또한 중요하다. 법률에 의한 명백한 임무의 부여와 관 에리 트와 지식 인간의 협력 또는 마찰의 정도가 정보 정책을 시행하는데 결정적인 요인이 됨을 현재 진행되고 있는 여러 시책 사항을 통하여 지적하였다. 문부성에서 의욕적인 정책으로 추진하여 소기의 성과를 거두고 있는 일본학술정보센터의 정책적 효과를 온라인 네트워크를 편성하는 기본 조직으로 주의 깊게 관찰할 대상임을 강조하였으며 과학기술청이 주관하는 일본 과학기술정보센터의 기능 또한 중요한 기관으로 간주됨을 분석하였다. 이들 기관 이외 에 광범위한 활동을 전개하고 있는 각급 사회 단체 연구소등 반관반민의 조직 또는 민간 레 벨의 조직은 본론에서는 제외되었다.

• 대한수학회보
• /
• 제58권6호
• /
• pp.1341-1354
• /
• 2021

Let r ≥ 2, and let k_i ≥ 2 for 1 ≤ i ≤ r. Mixed van der Waerden's theorem states that there exists a least positive integer w = w(k₁, k₂, k₃, …, k_r; r) such that for any n ≥ w, every r-colouring of [1, n] admits a k_i-term arithmetic progression with colour i for some i ∈ [1, r]. For k ≥ 3 and r ≥ 2, the mixed van der Waerden number w(k, 2, 2, …, 2; r) is denoted by w₂(k; r). B. Landman and A. Robertson [9] showed that for k < r < $\frac{3}{2}$(k - 1) and r ≥ 2k + 2, the inequality w₂(k; r) ≤ r(k - 1) holds. In this note, we establish some results on w₂(k; r) for 2 ≤ r ≤ k.

• Journal of Microbiology and Biotechnology
• /
• 제23권5호
• /
• pp.656-660
• /
• 2013

Pseudomonas fluorescens strain CL0145A was discovered at the New York State Museum Field Research Laboratory as an effective agent against the environmentally destructive zebra mussel, which has contaminated US waters. Dried cells of the microbe are being commercialized as an environmentally friendly solution to the problem. We found that antibiotic activity against the Gram-positive bacterium Bacillus subtilis is produced and excreted by this strain. We have carried out studies to optimize production of the antibiotic. Studies were begun in a complex corn meal medium. Activity was found in both cells and culture supernates and was maximal after one day of fermentation. Static fermentation conditions were found to be superior to shaken culture. Production of extracellular antibiotic in complex medium was found to be dependent on the content of sucrose and enzyme-hydrolyzed casein. Indeed, production was greater in sucrose plus enzyme-hydrolyzed casein than in the complex medium. Of a large number of carbon sources studied as improvements over sucrose, the best was glycerol. An examination of nitrogen sources showed that production was improved by replacement of enzyme-hydrolyzed casein with soy hydrolysates. Production in the simple glycerol-Hy-Soy medium was not improved by addition of an inorganic salt mixture or by complex nitrogen sources, with the exception of malt extract. In an attempt to keep the medium more defined, we studied the effect of amino acids and vitamins as replacements for malt extract. Of 21 amino acids and 7 vitamins, we found tryptophan, glutamine, biotin, and riboflavin to be stimulatory. The final medium contained glycerol, Hy-Soy, tryptophan, glutamine, biotin, and riboflavin.