• Structural Engineering and Mechanics
• /
• 제15권2호
• /
• pp.249-267
• /
• 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.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
• /
• pp.57-60
• /
• 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.

• 전기학회논문지
• /
• 제59권7호
• /
• pp.1332-1339
• /
• 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
• /
• 제45권2호
• /
• pp.261-266
• /
• 2002

저자들은 출생 후 호흡기 증상이 지속되어 오던 여아가 respiratory syncytial virus와 b형 헤모필루스 인플루엔자균에 의한 하기도 감염에 이환되면서 생후 4개월에 혈관륜으로 진단된 1예를 보고하는 바이다. 환아는 출생 후 협착음과 천명음 등의 잦은 호흡기 증상을 보였고, 3개월에 호흡 곤란을 주소로 입원하였으며 respiratory syncytial virus에 의한 세기관지염으로 치료받고 호전되었다. 퇴원 후 증상이 다시 악화되어 재입원 하였으며 b형 헤모필루스 인플루엔자균에 의한 기관염 및 폐렴이 확인되었고, 치료를 위해 기관내 튜브에 도관 삽입을 시도하였을 때 하부 기도에서 저항감이 감지되어 기도 부위의 해부학적 기형을 의심하게 되었다. 3차원 흉부 단층 촬영에서 이중 대동맥궁으로 인한 혈관륜이 확인되었고, 교정 수술을 시행한 후 좋은 경과를 보이고 있다.

• 한국소음진동공학회논문집
• /
• 제24권10호
• /
• pp.780-787
• /
• 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.

• 대한수학회지
• /
• 제53권5호
• /
• pp.1057-1075
• /
• 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.

• 대한토목학회논문집
• /
• 제26권2A호
• /
• pp.327-338
• /
• 2006

강구조물의 대표적인 현장이음방식인 고장력볼트 마찰이음은 볼트 축력의 관리가 엄격하기 때문에 많은 노동력과 시간을 필요로 하며, 미끄러짐 하중을 기준으로 설계가 이루어져 볼트의 높은 전단강도를 유효하게 이용하지 못하고, 그 결과 소요 볼트수가 많아지는 단점이 있다. 따라서 고장력볼트 마찰이음의 단점을 보완하고, 지압이음의 장점을 살린 전단링을 사용한 새로운 이음방식을 개발하여 기존의 고장력볼트 마찰이음과 비교실험을 실시하고 해석적 연구를 실시하였다. 그 결과 전단링을 이용한 새로운 이음방식은 전단링의 높은 전단강도로 저항하기 때문에 기존의 마찰이음보다 이음부의 내력이 크게 향상되는 것을 실험적으로 확인할 수 있었다. 한편 전단이음의 응력집중을 최소화하면서 최대의 연결강도를 유도하기 위해서는 전단링의 깊이 등의 설계 변수에 대한 추가적인 연구가 필요할 것으로 판단된다.

• Journal of Trauma and Injury
• /
• 제32권2호
• /
• pp.101-106
• /
• 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.

• 대한기계학회논문집A
• /
• 제27권11호
• /
• pp.1949-1957
• /
• 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
• /
• 제28권3호
• /
• pp.70-77
• /
• 2000

산뽕나무 심재추출물 중 다량으로 분리된 stilbenoid인 oxyresveratrol, resveratrol과 이들의 구조유사체를 합성하여 항균 및 항산화활성을 측정하고 화학구조와의 상관관계를 검토하였다. 항균활성은 진균에 대해서는 배지점적법으로, 세균에 대해서는 탁도측정법으로, 그리고 항산화활성은 지질산화억제율과 프리라디칼 소거능을 이용하여 검정하였다. 그 결과, 진균 및 세균에 대한 항균활성은 resveratrol이 oxyresveratrol보다 우수하였으며, 항산화활성은 oxyresveratrol이 resveratrol보다 우수하였다. 또한, Wittig 반응으로 합성한 6종의 stilbenoid의 항균활성은 B-ring의 수산기가 적을수록 활성이 높은 경향을 나타내어. 3,5-dihydroxystilbene (pinosylvin)과 같이 B-ring에 수산기가 없는 경우에 가장 높은 활성을 보였으며, trans type이 cis type보다 활성이 높았다. 그러나, 항산화활성은 B-ring의 수산기가 많을수록 활성이 높았으며, B-ring의 수산기가 ortho-diphenol 구조를 가지는 stilbenoid가 활성이 가장 높아, 2',3,3',5-와 3,3',4',5-tetrahydroxystilbene(piceatannol) 의 경우, 합성항산화제인 BHT보다는 높고 천연항산화제인 ${\alpha}$-tocopherol과는 동등한 효능을 보였다. 이상의 결과, 산뽕나무 심재로부터 단리된 resveratrol과 oxyresveratrol은 항균 및 높은 항산화활성을 가지는 것으로 판명되었으며, B-ring의 수산기의 수와 치환위치가 활성에 큰 영향을 미치는 것으로 판명되었다.