• Structural Engineering and Mechanics
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• v.15 no.2
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• pp.249-267
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• 2003

In this study, circular plates subjected to general type of loads and supported on a two-parameter elastic foundation are analysed. The stiffness, elastic bedding and soil shear effect matrices of a fully compatible ring sector plate element, developed by Saygun (1974), are obtained numerically assuming variable thickness of the element. Ring sector soil finite element is also defined to determine the deflection of the soil surface outside the domain of the plate in order to establish the interaction between the plate and the soil. According to Vallabhan and Das (1991) the elastic bedding (C) and shear parameters ($C_T$) of the foundation are expressed depending on the elastic constants ($E_s$, $V_s$) and the thickness of compressible soil layer ($H_s$) and they are calculated with a suitable iterative procedure. Using ring sector elements presented in this paper, permits the generalization of the loading and the boundary conditions of the soil outside the plate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.57-60
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• 2000

In this paper, it is purpose to develop a pulsed $CO_2$ laser with stable output at pulse repetition rate range of 2 KHz. We used a IGBT as a switching device. The laser cavity was fabricated as an axial and water cooled type. It was used a ring blower to increase a cooling effect The laser performance characteristics as parameters, such as pulse repetition rate, gas pressure have been investigated. The experiment was done under 3 electrode-type instead of 2 electrode-type. To achieve 3 electrode-type, we used two pulse-transformers which is operated parallel. As a result, the maximum output was about 28 W at the total pressure of 20 Torr, the gas mixture $Co_2$:$N_2$:He=1:9:15 and the pulse repetition rate of 1300 Hz.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1332-1339
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• 2010

This paper presents a large signal analysis of ring-type oscillators with feed forward and negative skewed delay scheme. The analysis yields the frequency increase factor due to two schemes. The large signal analysis is needed, because small signal model is limited to the initial stage of oscillation[1]. For verification of the frequency increase factor, simulation were done under the same conditions for the two different types of ring oscillators, i.e., with and without feed forward and negative skewed delay scheme. Simulation results are in good agreement with predictions based on analysis.

• Clinical and Experimental Pediatrics
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• v.45 no.2
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• pp.261-266
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• 2002

Vascular ring, originating from abnormal regression of the aortic arch during fetal life, can cause prolonged and recurrent respiratory symptoms and dysphagia when the diagnosis is delayed. We report a 4 month old girl with vascular ring, who had been treated for persistent respiratory symptoms including stridor, wheezing, and dyspnea soon after birth. Initially her respiratory symptoms were thought to be due to bronchiolitis, for which respiratory syncytial virus was confirmed by immunofluorescent staining. Her clinical course was again complicated with tracheitis and pneumonia due to Haemophilus influenzae type b. The possibility of anatomical anomaly was investigated when it was felt to be difficult to insert a suction catheter deep down through a endotracheal tube which was placed for adequate ventilatory management. A three-dimensional chest CT revealed a vascular ring consisting of a double aortic arch. For 5 months following surgery, her respiratory symptoms have slowly been improving. She developed another episode of pneumonia which was milder than the one which occurred before the surgery.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.10
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• pp.780-787
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• 2014

This paper experimentally deals with the vibration characteristics of flat ring transducers used for ultrasonic sensors and actuators. Radial vibration mode, which is the fundamental mode of a thin piezoelectric transducer, was measured by a laser in-plane vibrometer. An impedance analyzer was used to measure natural frequencies. The results measured by experiments verified theoretical predictions. The vibration characteristics of ring transducers were identified according to the outer diameter size. The shape of the fundamental mode is almost uniform but slightly decreases from the inner to the outer circumferential surfaces. The natural frequency of the fundamental mode decreases as the outer diameter increases. It appears that the ring type transducer is suitable to excite uniformly distributed vibration on a flat surface.

• Journal of the Korean Mathematical Society
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• v.53 no.5
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• pp.1057-1075
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• 2016

Let R be a ring in which Nil(R) is a divided prime ideal of R. Then, for a suitable property X of integral domains, we can define a ${\phi}$-X-ring if R/Nil(R) is an X-domain. This device was introduced by Badawi [8] to study rings with zero divisors with a homomorphic image a particular type of domain. We use it to introduce and study a number of concepts such as ${\phi}$-Schreier rings, ${\phi}$-quasi-Schreier rings, ${\phi}$-almost-rings, ${\phi}$-almost-quasi-Schreier rings, ${\phi}$-GCD rings, ${\phi}$-generalized GCD rings and ${\phi}$-almost GCD rings as rings R with Nil(R) a divided prime ideal of R such that R/Nil(R) is a Schreier domain, quasi-Schreier domain, almost domain, almost-quasi-Schreier domain, GCD domain, generalized GCD domain and almost GCD domain, respectively. We study some generalizations of these concepts, in light of generalizations of these concepts in the domain case, as well. Here a domain D is pre-Schreier if for all $x,y,z{\in}D{\backslash}0$, x | yz in D implies that x = rs where r | y and s | z. An integrally closed pre-Schreier domain was initially called a Schreier domain by Cohn in [15] where it was shown that a GCD domain is a Schreier domain.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.327-338
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• 2006

Friction type high tension bolted joints is one of the most common steel structure connections and requires significant concerns on axial force of the bolts. However, its high shear capacity is not appropriately considered in design and hence the number of bolts is over-designed than actually required. It is primarily due to a slip-load-based design method. This study, therefore, suggests a new technology of connection using a shear ring, which may reduce the shortcomings from the friction-typed high tension bolted joints and maximize the advantages from the bearing-typed joints. Experimental and numerical studies were performed to compare the capacity of the suggested method with traditional high tension bolted joints. From the results, it is known that the suggested connections has higher bearing capacity than friction-typed high tension bolted joints due to the higher shear resistance from the ring. For further study, it may be necessary to investigate on design parameters including the depth of shear ring, for increased connection capacity.

• Journal of Trauma and Injury
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• v.32 no.2
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• pp.101-106
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• 2019

Purpose: The purpose of this study was to determine the essential factors for prompt arrangement of angio-embolization in patients with pelvic ring fractures. Methods: A total of 62 patients with pelvic ring fractures who underwent angio-embolization in Dankook University Hospital from March 2013 to June 2018 were retrospectively reviewed. There were 38 men and 24 women with a mean age of 59.8 years. The types of pelvic ring fractures were categorized according to the Tile classification. Patient variables included sex, initial hemoglobin concentration, initial systolic blood pressure, transfused packed red blood cells within 24 hours, Injury Severity Score (ISS), mortality rate, length of hospital stay, and time to angio-embolization. Results: The most common pelvic fracture pattern was Tile type B (n=34, 54.8%). The mean ISS was $27.3{\pm}10.9$ with 50% having an $ISS{\geq}25$. The mean time to angio-embolization from arrival was $173.6{\pm}89minutes$. Type B ($180.1{\pm}72.3minutes$) and type C fractures ($174.7{\pm}91.3minutes$) required more time to angio-embolization than type A fractures ($156.6{\pm}123minutes$). True arterial bleeding was identified in types A (35.7%), B (64.7%), and C (71.4%). Conclusions: It is important to save time to reach the angio-embolization room in treating patients with pelvic bone fractures. Trauma surgeons need to consider prompt arrangement of angio-embolization when encountering Tile type B or C pelvic fractures due to the high risk of true arterial bleeding.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.11
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• pp.1949-1957
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• 2003

A hybrid finite element analysis was used to analyze the influence of ring gear rim thickness and spline number on the static properties of a planetary gear system with manufacturing errors. Both of these parameters affected the bearing force and critical stress. The effect of changes in the rim thickness on the load sharing between the gears depended on the type of manufacturing error. Ring flexibility improved the load sharing between planetary gears only in systems with planet tooth thickness or planet tangential errors; for other types of error, ring flexibility worsened the load sharing. To improve load sharing, rim thickness and spline number should be controlled within a specific range. The minimum rim thickness limit should be determined considering not only the critical stress but also the load sharing. The effect of the ring gear boundary condition was more apparent in a system with errors than in a normal system.

• Journal of the Korean Wood Science and Technology
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• v.28 no.3
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• pp.70-77
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• 2000

Among four compounds such as oxyresveratrol, resveratrol, morin and afzelechin isolated from the heartwood of Morns bombycis, oxyresveratrol and resveratrol which belong to stilbenoid indicated high antioxidative and antimicrobial activity, respectively. Based on this result, this experiment was carried out to elucidate the relationship between biological activities of stilbenoids and their chemical structures using two isolated and six synthesized ones prepared by Wittig reaction. Antimicrobial activity of 3,5-dihydroxystilbene(pinosylvin) devoid of hydroxyl group of B-ring was the best among the tested stilbenoids. Antimicrobial activities of the stilbenoids showed negative dependency on the number of hydroxyl groups of B-ring, that is, the fewer number of hydroxyl groups of B-ring, the higher antimicrobial activity. On the other hand, antioxidative activities of the stilbenoids indicated a positive relationship with the number of hydroxyl groups of B-ring. In tetrahydroxystilbenoids, antioxidative activities of the compounds possessing ortho-diphenol structure, 2',3,3',5- and 3,3',4',5-tetrahydroxystilbene, were superior to the others. As a result, it was concluded that resveratrol and oxyresveratrol isolated from the heartwood of M. bombycis had antimicrobial and high antioxidative activities, and these activities of stilbenoids were also dependent on the number and position of hydroxyl groups of B-ring.