• 대한수학회보
• /
• 제59권5호
• /
• pp.1317-1325
• /
• 2022

In this note, we prove that an Artinian local ring is G-semisimple (resp., SG-semisimple, 2-SG-semisimple) if and only if its maximal ideal is G-projective (resp., SG-projective, 2-SG-projective). As a corollary, we obtain the global statement of the above. We also give some examples of local G-semisimple rings whose maximal ideals are n-generated for some positive integer n.

• 충청수학회지
• /
• 제32권2호
• /
• pp.191-193
• /
• 2019

It is shown that a left Ore extension $D[x;{\sigma}]$ over a division ring D is a left Goldie ring with no zero-divisor and that its left Goldie quotient is an injective hull of $D[x;{\sigma}]$.

• 대한수학회보
• /
• 제46권1호
• /
• pp.135-146
• /
• 2009

In the present note we study the properties of weak Armendariz rings, and the connections among weak Armendariz rings, Armendariz rings, reduced rings and IFP rings. We prove that a right Ore ring R is weak Armendariz if and only if so is Q, where Q is the classical right quotient ring of R. With the help of this result we can show that a semiprime right Goldie ring R is weak Armendariz if and only if R is Armendariz if and only if R is reduced if and only if R is IFP if and only if Q is a finite direct product of division rings, obtaining a simpler proof of Lee and Wong's result. In the process we construct a semiprime ring extension that is infinite dimensional, from given any semi prime ring. We next find more examples of weak Armendariz rings.

• 대한수학회보
• /
• 제56권3호
• /
• pp.659-666
• /
• 2019

In this paper, we consider a conjecture of I. N. Herstein for local commutators of symmetric elements and unitary elements of division rings. For example, we show that if D is a finite dimensional division ring with involution ${\star}$ and if $a{\in}D^*=D{\setminus}\{0\}$ such that local commutators $axa^{-1}x^{-1}$ at a are radical over the center F of D for every $x{\in}D^*$ with $x^{\star}=x$, then either $a{\in}F$ or ${\dim}_F\;D=4$.

• Korean Journal of Mathematics
• /
• 제10권2호
• /
• pp.149-155
• /
• 2002

We develop some basic properties of $t$-fuzzy ideals in a monoid or a group and find the sufficient conditions for a fuzzy set in a division ring to be a $t$-fuzzy subring and the necessary and sufficient conditions for a fuzzy set in a division ring to be a $t$-fuzzy ideal.

• 한국전자파학회논문지
• /
• 제15권6호
• /
• pp.533-539
• /
• 2004

본 논문에서는 이동통신 시스템에 사용할 수 있는 대역 통과 필터를 얻기 위해서, 스터브를 부가한 링 공진기로 2 ㎓ 대역 필터를 설계하였다. 3단 광대역 BPF는 스터브를 부가한 링 공진기률 이용하여 설계되었으며, 연속적인 3단 링 공진기를 사용함으로써 원하는 기본 통과 대역의 특성을 향상시켰다. 그리고 회로 구성요소의 특성 임피던스 값은 Powell의 미분을 필요로 하지 않는 최소자승법에 의해 구하여 계산하였으며, 실험결과는 계산 결과와 거의 일치하였다.

• 식물병연구
• /
• 제19권4호
• /
• pp.300-307
• /
• 2013

This study was conducted to determine the occurrence of leaf rot and leaf ring spot, caused by Rhizoctonia solani in Chinese cabbage under seedling nursery and cultivation greenhouses. Symptoms of leaf rot and leaf ring spot were found in three Chinese cabbage cultivars, Brassica campestris subsp. pekinensis, 'Ryeokgwang', 'Daetong', and 'CR mat'. In Hwacheon, the disease incidence was 73.8% in the seedling stage of the Chinese cabbage. In Icheon, the symptoms were observed on the upper leaves of the Chinese cabbage cultivar, 'Norangmini' with 20.5% of disease incidence. The symptoms appeared as primary lesions consisting of small, circular necrotic ring spots with gray color, 1.4-3.0 mm in diameter, accompanied by secondary rot lesions with large irregular borders of leaves. The color of mycelial mat of 20 isolates was dark brown and light brown. The average hyphal diameter of all the isolates was within 5.01-11.12 ${\mu}m$. Among the 20 strains isolated from Chinese cabbage, 16 isolates and four isolates anastomosed with the AG-1 (IB) and AG-1 (IC), respectively. Twenty isolates tested were only virulent on foliage parts of Chinese cabbage leaves but were avirulent on stem parts of the plants. Based on the mycological characteristics and pathogenicity test on host plants, the fungus was identified as Rhizoctonia solani.

• Bulletin of the Korean Chemical Society
• /
• 제32권8호
• /
• pp.2737-2742
• /
• 2011

Ring-opening metathesis polymerization (ROMP) of an ethyl-substituted tetracyclododecene (8-ethyltetracyclo[$4.4.0.1^{2,5}.1^{7,10}$] dodec-3-ene, Et-TCD) was carried out in the presence of a ternary catalyst system consisting of $WCl_6$, triisobutyl aluminium (iso$Bu_3Al$), and ethanol. The optimal molar ratio of Et-TCD/$WCl_3$/iso-$Bu_3Al$/ethanol was found as 500/1/3/2 at which the yield of ring-opened polymer was 100%. 1-Hexene was shown to be an effective molecular weight controlling agent for ROMP reaction of Et-TCD. The hydrogenation of the ring opened polymer (p-Et-TCD) was conducted successfully using Pd(5 wt %)/${\gamma}$-$Al_2O_3$ at $80^{\circ}C$ for 1 h. Chemical structures of p-Et-TCD and its hydrogenated product($H_2$-p-Et-TCD) were characterized using 2D NMR techniques ($^1H-^1H$ COSY and $^1H-^{13}C$ HSQC). The changes of physical properties such as thermal stability, glass transition temperature and light transmittance after the hydrogenation were also investigated using TGA, DSC, and UV.

• Bulletin of the Korean Chemical Society
• /
• 제24권11호
• /
• pp.1567-1568
• /
• 2003

• 박물관보존과학
• /
• 제16권
• /
• pp.56-81
• /
• 2015

족자 고리는 끈이나 유소를 고정시켜 걸 수 있도록 하는 장황 부속품으로 형태가 다양하며 여러 금속재를 사용하여 제작되었다. 현재 전통 형식의 고리는 대부분 개장으로 인해 유실되었으며, 일본식 고리를 사용하고 있다. 따라서 본 연구에서는 국립중앙박물관에 소장된 전통 족자 19점을 대상으로 고리의 형태와 제작기법, 성분을 조사하여 옛 형태를 복원해 보고자 하였다. 의궤 내용에서 고리는 원환(圓環), 국화동(菊花童), 배목(排目) 등 고유의 명칭으로 기록되어 있다. 휴대용 엑스선 형광분석기(portable X-ray fluorescence, Artax, Rontec)로 성분을 분석한 결과, 전통 형식의 고리는 황동, 철, 은-구리합금 등 다양한 금속재로 확인되었다. 구리와 아연이 주성분인 황동은 17점 족자 고리에 사용되었다. 전 윤시달 초상(신2339)의 배목에서는 철을 사용하였으며, 주석-납 합금으로 도금하였다. 이서구 초상(신1065)에서는 고리 전체가 은-구리합금으로 제작되었음을 확인하였다. 광학현미경(Leica, M205A)으로 제작 방법을 조사한 결과 원환은 금속봉을 절단한 뒤 둥글게 휘어 만든 유형과 주조로 제작된 유형으로 확인되었다. 배목은 주조한 합금으로 봉재나 판재를 만들고 다시 단조과정을 거쳐 제작하였고, 배목장식은 금속판재를 잘라 형태를 만든 후 축조와 타출기법 등으로 무늬를 새겨 장식하였다.