• East Asian mathematical journal
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• v.34 no.1
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• pp.39-46
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• 2018

In this article we consider rings whose Jacobson radical contains all the nilpotent elements, and call such a ring an NJ-ring. The class of NJ-rings contains NI-rings and one-sided quasi-duo rings. We also prove that the Koethe conjecture holds if and only if the polynomial ring R[x] is NJ for every NI-ring R.

• Genomics & Informatics
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• v.8 no.4
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• pp.170-176
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• 2010

The Ribonucleotide reductases (RNR) are essential enzymes that catalyze the conversion of nucleotides to deoxynucleotides in DNA replication and repair in all living organisms. The RNRs operate by a free radical mechanism but differ in the composition of subunit, cofactor required and regulation by allostery. Based on these differences the RNRs are classified into three classesclass I, class II and class III which depend on oxygen, adenosylcobalamin and S-adenosylmethionine with an iron sulfur cluster respectively for radical generation. In this article thirty seven sequences belonging to each of the three classes of RNR were analyzed by using various tools of bioinformatics. Phylogenetic analysis, dot-plot comparisons and motif analysis was done to identify a number of differences in the three classes of RNRs. In this research article, we have attempted to decipher evolutionary relationship between the three classes of RNR by using bioinformatics approach.

• Kyungpook Mathematical Journal
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• v.46 no.2
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• pp.261-271
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• 2006

In this paper, we investigate and characterize the class of A-semirings. A characterization of the Thierrin radical of a proper ideal of an A-semiring is given. Moreover, when P is a Q-ideal in the semiring R, it is shown that P is primary if and only if R/P is nilpotent.

• Journal of Gastric Cancer
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• v.13 no.4
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• pp.207-213
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• 2013

Purpose: We investigated early postoperative morbidity and mortality in patients with liver cirrhosis who had undergone radical gastrectomy for gastric cancer. Materials and Methods: We retrospectively reviewed the medical records of 41 patients who underwent radical gastrectomy at the Chonnam National University Hwasun Hospital (Hwasun-gun, Korea) between August 2004 and June 2009. There were few patients with Child-Pugh class B or C; therefore, we restricted patient selection to those with Child-Pugh class A. Results: Postoperative complications were observed in 22 (53.7%) patients. The most common complications were ascites (46.3%), postoperative hemorrhage (22.0%) and wound infection (12.2%). Intra-abdominal abscess developed in one (2.4%) patient who had undergone open gastrectomy. Massive ascites occurred in 4 (9.8%) patients. Of the patients who underwent open gastrectomy, nine (21.9%) patients required blood transfusions as a result of postoperative hemorrhage. However, most of these patients had advanced gastric cancer. In contrast, most patients who underwent laparoscopic gastrectomy had early stage gastric cancer, and when the confounding effect from the different stages between the two groups was corrected statistically, no statistically significant difference was found. There was also no significant difference between open and laparoscopic gastrectomy in the occurrence rate of other postoperative complications such as ascites, wound infection, and intra-abdominal abscess. No postoperative mortality occurred. Conclusions: Laparoscopic gastrectomy is a feasible surgical procedure for patients with moderate hepatic dysfunction.

• Bulletin of the Korean Mathematical Society
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• v.60 no.6
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• pp.1463-1475
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• 2023

In this paper, we introduce a class of rings generalizing unit regular rings and being a subclass of semipotent rings, which is called idempotent unit regular. We call a ring R an idempotent unit regular ring if for all r ∈ R - J(R), there exist a non-zero idempotent e and a unit element u in R such that er = eu, where this condition is left and right symmetric. Thus, we have also that there exist a non-zero idempotent e and a unit u such that ere = eue for all r ∈ R - J(R). Various basic characterizations and properties of this class of rings are proved and it is given the relationships between this class of rings and some well-known classes of rings such as semiperfect, clean, exchange and semipotent. Moreover, we obtain some results about when the endomorphism ring of a module in a class of left R-modules X is idempotent unit regular.

• Kyungpook Mathematical Journal
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• v.54 no.4
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• pp.595-606
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• 2014

In this paper three more right Jacobson-type radicals, $J^r_{g{\nu}}$, are introduced for near-rings which generalize the Jacobson radical of rings, ${\nu}{\in}\{0,1,2\}$. It is proved that $J^r_{g{\nu}}$ is a special radical in the class of all near-rings. Unlike the known right Jacobson semisimple near-rings, a $J^r_{g{\nu}}$-semisimple near-ring R with DCC on right ideals is a direct sum of minimal right ideals which are right R-groups of type-$g_{\nu}$, ${\nu}{\in}\{0,1,2\}$. Moreover, a finite right $g_2$-primitive near-ring R with eRe a non-ring is a near-ring of matrices over a near-field (which is isomorphic to eRe), where e is a right $g_2$-primitive idempotent in R.

• Applied Chemistry for Engineering
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• v.1 no.1
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• pp.1-10
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• 1990

Polysilane derivatives are attracting considerable attention as a new class of material since 1980. The preparation methods of low molecular weight, cyclic, and high molecular weight polysilane derivatives are described, and also photochemistry characteristics for silicon-silicon single bond and for the nature of the substituent on silicon backbone are discussed. Polysilanes may be used as a precursors to silicon carbide fiber, as photoresist in microelectronics, as photoconductor, and as photoinitatior for free radical polymerization.

• International Journal of Advanced Culture Technology
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• v.7 no.1
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• pp.174-185
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• 2019

The purpose of this study was to research the experimental dance drama of the world-class choreographer Pina Bausch who, in the latter half of the twentieth century, broke the boundaries of genres with radical experimentation and overcame the limits of expressionism dance tradition, creating her exclusive dance drama. Pina Bausch was born in Germany and naturally inherited the expressionist dance tradition, but did not stay there and introduced the post-Brecht drama theater through radical experimentation. Her bold attempts have overcome the limitations of the expressionist tradition and have revolutionized the genre of dance and have played a role in expanding dance arts while pioneering her own dance language.

• Journal of Preventive Medicine and Public Health
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• v.43 no.4
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• pp.330-340
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• 2010

Objectives: This study aims to evaluate and explain the socioeconomic inequalities of all-cause mortality after breast cancer surgery in South Korea. Methods: This population based study included all 8868 females who underwent radical mastectomy for breast cancer between January 2002 and June 2003. Follow-up for mortality continued from January 2002 to June 2006. The patients were divided into 4 socioeconomic classes according to their socioeconomic status as defined by the National Health Insurance contribution rate. The relationship between socioeconomic status and all-cause mortality after breast cancer surgery was assessed using the Cox proportional hazards model with adjusting for age, the Charlson’s index score, emergency hospitalization, the type of hospital and the hospital ownership. Results: Those in the lowest socioeconomic status group had a significantly higher hazard ratio of 2.09 (95% CI =1.50 - 2.91) compared with those in the highest socioeconomic group after controlling for all the identifiable confounding variables. For allcause mortality after radical mastectomy, all the other income groups showed significantly higher 3-year mortality rates than did the highest income group. Conclusions: The socioeconomic status of breast cancer patients should be considered as an independent prognostic factor that affects all-cause mortality after radical mastectomy, and this is possibly due to a delayed diagnosis, limited access or minimal treatment leading to higher mortality. This study may provide tangible support to intensify surveillance and treatment for breast cancer among low socioeconomic class women.

• Kyungpook Mathematical Journal
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• v.46 no.4
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• pp.603-613
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• 2006

Near-rings considered are right near-rings and R is a near-ring. $J_0^r(R)$, the right Jacobson radical of R of type-0, was introduced and studied by the present authors. In this paper $J_1^r(R)$ and $J_2^r(R)$, the right Jacobson radicals of R of type-1 and type-2 are introduced. It is proved that both $J_1^r$ and $J_2^r$ are radicals for near-rings and $J_0^r(R){\subseteq}J_1^r(R){\subseteq}J_2^r(R)$. Unlike the left Jacobson radical classes, the right Jacobson radical class of type-2 contains $M_0(G)$ for many of the finite groups G. Depending on the structure of G, $M_0(G)$ belongs to different right Jacobson radical classes of near-rings. Also unlike left Jacobson-type radicals, the constant part of R is contained in every right 1-modular (2-modular) right ideal of R. For any family of near-rings $R_i$, $i{\in}I$, $J_{\nu}^r({\oplus}_{i{\in}I}R_i)={\oplus}_{i{\in}I}J_{\nu}^r(R_i)$, ${\nu}{\in}\{1,2\}$. Moreover, under certain conditions, for an invariant subnear-ring S of a d.g. near-ring R it is shown that $J_2^r(S)=S{\cap}J_2^r(R)$.