• Kyungpook Mathematical Journal
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• v.47 no.3
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• pp.363-372
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• 2007

An element $a$ in a ring R is called left morphic if $$R/Ra{\simeq_-}1(a)$$. A ring is called left morphic if every element is left morphic. In this paper, an element $a$ in a ring R is called left ${\pi}$-morphic (resp. left G-morphic) if there exists a positive number $n$ such that $a^n$ (resp. $a^n{\neq}0$) is left morphic. A ring R is called left ${\pi}$-morphic (resp. left G-morphic) if every element is left ${\pi}$-morphic (resp. left G-morphic). The Morita invariance of left ${\pi}$-morphic (resp. left G-morphic) rings is discussed. Several relevant properties are proved. In particular, it is shown that a left Noetherian ring R with $M_4(R)$ left G-morphic or $M_2(R)$ left morphic is QF. Some known results of left morphic rings are extended to left G-morphic rings and left ${\pi}$-morphic rings.

• Kyungpook Mathematical Journal
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• v.53 no.3
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• pp.397-406
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• 2013

A ring R is called a left (right) SF-ring if simple left (right) R-modules are flat. It is still unknown whether a left (right) SF-ring is von Neumann regular. In this paper, we give some conditions for a left (right) SF-ring to be (a) von Neumann regular; (b) strongly regular; (c) division ring. It is proved that: (1) a right SF-ring R is regular if maximal essential right (left) ideals of R are weakly left (right) ideals of R (this result gives an affirmative answer to the question raised by Zhang in 1994); (2) a left SF-ring R is strongly regular if every non-zero left (right) ideal of R contains a non-zero left (right) ideal of R which is a W-ideal; (3) if R is a left SF-ring such that $l(x)(r(x))$ is an essential left (right) ideal for every right (left) zero divisor x of R, then R is a division ring.

• Kyungpook Mathematical Journal
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• v.51 no.1
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• pp.93-108
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• 2011

A ring R is called left weakly np- injective if for each non-nilpotent element a of R, there exists a positive integer n such that any left R- homomorphism from $Ra^n$ to R is right multiplication by an element of R. In this paper various properties of these rings are first developed, many extending known results such as every left or right module over a left weakly np- injective ring is divisible; R is left seft-injective if and only if R is left weakly np-injective and $_RR$ is weakly injective; R is strongly regular if and only if R is abelian left pp and left weakly np- injective. We next introduce the concepts of left weakly pp rings and left weakly C2 rings. In terms of these rings, we give some characterizations of (von Neumann) regular rings such as R is regular if and only if R is n- regular, left weakly pp and left weakly C2. Finally, the relations among left C2 rings, left weakly C2 rings and left GC2 rings are given.

• Kyungpook Mathematical Journal
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• v.56 no.3
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• pp.861-866
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• 2016

A ring R called left SF if its simple left modules are at. Regular rings are known to be left SF-rings. However, till date it is unknown whether a left SF-ring is necessarily regular. In this paper, we prove the strong regularity of left (right) complement bounded left SF-rings. We also prove the strong regularity of a class of generalized semi-commutative left SF-rings.

• International Journal of Highway Engineering
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• v.15 no.3
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• pp.177-189
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• 2013

PURPOSES: This study aims to suggest a proper left-turn treatment method for the bicycle traffic flow at four-legged intersections. METHODS: Four types of crossing methods are proposed and analyzed : (1) indirect left turn, (2) direct left turn, (3) direct left turn on a Bike Box, and (4) direct left turn on bike left turn lane. The VISSIM simulation tests were conducted based on forty-eight operation scenarios prepared by varying vehicle and bicycle traffic volumes. RESULTS : The results from the four-legged signalized intersections suggest that (1) the indirect left turn is appropriate when vehicle demand is high, (2) the direct left turn is efficient on most traffic situation but the safety is a concern, (3) the direct left turn on a Bike Box is appropriate when bicycle demand is high while vehicle demand is not, and (4) the direct left turn on a bike left turn lane is appropriate when both vehicle and bicycle demand are low. CONCLUSIONS : The direct left turn of bicycle provides more efficiency than the indirect left turn at the four-legged intersections but to apply the methods and to study more, advanced evaluation methods, related law, and insurance programs are needed.

• Journal of Chest Surgery
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• v.23 no.4
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• pp.640-645
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• 1990

We have performed four left lung reimplantation and right pulmonary artery ligation in dogs for six months from March 1989 to September 1989 at the Thoracic & Cardiovascular Surgery department, Yonsei University, College of Medicine, Seoul, Korea. Excised left lungs were perfused with 200cc of 4oC cold saline at a pressure of 60cmH2O through left pulmonary artery & preserved in 4 oC cold saline for about 20 mins. Left lung reimplantation were proceeded with inferior pulmonary vein, superior pulmonary vein, left pulmonary artery and left main bronchus in order. The main pulmonary artery pr. were 39/21[31], 22/12[15], 25/9[15] and 54/17[37] mmHg each after right pulmonary artery ligation on left reimplanted dogs, Right pul a. ligations were performed 9 days, 12 days, 16 days and 19 days after left lung reimplantation. Two dogs died at 10 days 21 days, after right pul. a. ligations in left reimplanted dogs. The remaining two dogs were sacrificed at 18 days, 21 days after right pul. a. ligation in left reimplanted dogs. Autopsy findings showed narrowing of left superior pul. vein anastomotic site in two narrowing of left pulmonary artery anastomotic site in one narrowing of left sup. pul vein & pneumonia of left lung in one. In the lung transplantation, it was thought to be important that the anastomosis of pulmonary artery and especially pulmonary vein be done with particular precaution for early and late stenosis.

• Kyungpook Mathematical Journal
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• v.48 no.4
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• pp.651-663
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• 2008

In this paper, we first study some characterizations of left MC2 rings. Next, by introducing left nil-injective modules, we discuss and generalize some well known results for a ring whose simple singular left modules are Y J-injective. Finally, as a byproduct of these results we are able to show that if R is a left MC2 left Goldie ring whose every simple singular left R-module is nil-injective and GJcp-injective, then R is a finite product of simple left Goldie rings.

• Korean Journal of Acupuncture
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• v.18 no.1
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• pp.81-94
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• 2001

We could summerize the concept of the right and left mentioned in Nai-Gyung and some literature of oriental medicine as follow At first the right and left is a directional right and left which implys left-liver-right-lung(左肝右肺), left-yang-right-eum(左陽右陰), secondly it is also the road of eumyang which implys man-left-woman-right(男左女右), left-blood-right-ki(左血右氣), left-sinsu-right-myungmon(左腎水右命門), and left-right of pulse. left-liver-right-lung(左肝右肺), left-yang-right-eum(左陽右陰) and man-left-woman-right(男左女右) are expressions of the movement of yang which is a core of chang, at the same time, left-blood-right-ki(左血右氣), left-sinsu-right-myungmon(左腎水右命門), and left-right of pulse are expressions of the eum in response to the movement of yang. (go up and down of water and fire) Finally, both a directional right and left and a road of eumyang mean a road of going up and down of eumyang so, this is very important index in circulation and keeping ballance of eumyang (ki-Hyul:氣血) in the human body therefore, we can treat a disease with acupuncture in the use of this charater, for example when a disease occurs in the left side, we can treat it with acupuncture in the right side, the same applys to right.

• Bulletin of the Korean Mathematical Society
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• v.43 no.2
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• pp.299-307
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• 2006

The following results ale extended from P-injective rings to AP-injective rings: (1) R is left self-injective regular if and only if R is a right (resp. left) AP-injective ring such that for every finitely generated left R-module M, $_R(M/Z(M))$ is projective, where Z(M) is the left singular submodule of $_{R}M$; (2) if R is a left nonsingular left AP-injective ring such that every maximal left ideal of R is either injective or a two-sided ideal of R, then R is either left self-injective regular or strongly regular. In addition, we answer a question of Roger Yue Chi Ming [13] in the positive. Let R be a ring whose every simple singular left R-module is Y J-injective. If R is a right MI-ring whose every essential right ideal is an essential left ideal, then R is a left and right self-injective regular, left and right V-ring of bounded index.

• Journal of Medicine and Life Science
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• v.20 no.3
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• pp.131-134
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• 2023

Here, we present a case of a 56-year-old man with acute myocardial infarction. The patient underwent percutaneous coronary intervention (PCI) at the left main bifurcation and mid-left anterior descending artery using drugeluting stents. Four months after the PCI, the patient was readmitted for cardiac arrest. Coronary angiography (CAG) revealed stent thrombosis in the left main-to-proximal left anterior descending artery and in-stent restenosis in the left main-to-proximal left circumflex artery. We performed balloon angioplasty at the left main to mid-left anterior descending artery and left main to proximal left circumflex artery stents; subsequently, blood flow was fully restored. However, contrast agent extravasation was observed outside the mid-portion of the left main artery to the proximal left anterior descending artery stent, indicating the presence of a coronary artery aneurysm (CAA) outside the stent. After guideline-directed medical therapy with dual antiplatelet agents and high-intensity statins, follow-up CAG revealed near-resolution of the CAA, absence of stenotic lesions, and good blood flow.