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세가지 니켈 티타늄 파일의 휨과 비틀림 조건에서의 응력 분포에 관한 3차원 유한요소 연구
김태오,이찬주,김병민,박정길,허복,김현철 大韓齒科保存學會 2008 Restorative Dentistry & Endodontics Vol.33 No.4
이 연구의 목적은 세가지 니켈-티타늄 파일의 휨과 회전 조건 하에서의 응력 분포를 유한요소 모형을 이용하여 비교하는 것이다. ProFile .06/#30, ProTaper와 ProTaper Universal의 F3파일을 마이크로컴퓨터 단층촬영을 하고 reverse engineering을 통하여 세 니켈 티타늄 파일의 구조를 얻고 삼차원 유한요소모형을 제작하였다. 니켈 티타늄 합금의 비선형적인 물리적 성질을 반영하고 ABAQUS 프로그램을 이용하여 휨과 회전 조건 하에서의 기계적인 움직임을 수학적으로 예측 분석하였다. U-형태의 단면 구조를 가진 ProFile이 모형 가운데 가장 좋은 휨 성질을 나타냈다. 동일한 휨량 조건에서는 볼록한 삼각형 단면의 ProTaper가 다른모형보다 많은 힘을 필요로 하였으며, 반면에 가장 높은 von Mises 응력은 ProTaper Universal의 단면에서 움푹 파인 부위에 집중되었다. ProFile 모형은 동일한 크기의 회전력에 대해 가장 큰 응력 집중을 U-형 구 부위에 나타냈다. ProTaper 모형은 다른 모형에 비해 동일량을 비틀기 위해 더 많은 힘을 필요로 하였으며, 반면에 동량의 비틀림에서는 가장 높은 von Mises 응력이 ProTaper Universal의 단면에서 움푹 파인 부위에 집중되었다. Flexibility and fracture properties determine the performance of NiTi rotary instruments. The purpose of this study was to evaluate how geometrical differences between three NiTi instruments affect the deformation and stress distributions under bending and torsional conditions using finite element analysis. Three NiTi files (ProFile .06 / #30, F3 of ProTaper and ProTaper Universal) were scanned using a Micro-CT. The obtained structural geometries were meshed with linear, eight-noded hexahedral elements. The mechanical behavior (deformation and von Mises equivalent stress) of the three endodontic instruments were analyzed under four bending and rotational conditions using ABAQUS finite element analysis software. The nonlinear mechanical behavior of the NiTi was taken into account. The U-shaped cross sectional geometry of ProFile showed the highest flexibility of the three file models. The ProTaper, which has a convex triangular cross-section, was the most stiff file model. For the same deflection, the ProTaper required more force to reach the same deflection as the other models, and needed more torque than other models for the same amount of rotation. The highest von Mises stress value was found at the groove area in the cross-section of the ProTaper Universal. Under torsion, all files showed highest stresses at their groove area. The ProFile showed highest von Mises stress value under the same torsional moment while the ProTaper Universal showed the highest value under same rotational angle.
Case Reports : Primary non-Hodgkin`s Lymphoma of the Bladder with Bone Marrow Involvement
Kil Chan Oh,Dae Young Zang 대한내과학회 2003 The Korean Journal of Internal Medicine Vol.18 No.1
Involvement of the lower urinary tract by advanced non-Hodgkin`s lymphoma (NHL) has been reported in up to 13% of cases, but primary NHL of the urinary bladder is very rare. A 35-year-old man was admitted to our hospital with a chief complaint of gross he
오길찬 ( Kil Chan Oh ),박상훈 ( Sang Hoon Park ),임해성 ( Hae Sung Lim ),송진영 ( Jin Young Song ),박철희 ( Chul Hee Park ),한태호 ( Tae Ho Hahn ),박현주 ( Hyun Ju Park ),이동근 ( Dong Keun Lee ),김종혁 ( Jong Hyeok Kim ),장웅기 ( 대한소화기학회 2003 대한소화기학회지 Vol.41 No.2
Pregnancy in patients with primary biliary cirrhosis (PBC) is uncommon and only a few cases have been reported in the world literature. Thus, there is no report on the outcome and natural history of pregnancy in patients with primary biliary cirrhosis. He
오길찬 ( Kil Chan Oh ),박상훈 ( Sang Hoon Park ),박진철 ( Jin Cheol Park ),진도균 ( Do Kyun Jin ),박철성 ( Chul Sung Park ),김경오 ( Kyong Oh Kim ),장현주 ( Hyun Joo Jang ),이자영 ( Ja Young Lee ),박철희 ( Cheol Hee Park ),한태호 대한소화기학회 2005 대한소화기학회지 Vol.45 No.1
Background/Aims: Nonalcoholic fatty liver disease (NAFLD) has been characterized by a wide spectrum of liver damages that span from steatosis to cryptogenic liver cirrhosis and even to hepatocellular carcinoma (HCC). The aims of this study were to determi
Ursolic acid regulates high glucose-induced apoptosis
Oh, Chang Joo,Kil, In Sup,Park, Chan Ik,Yang, Chae Ha,Park, Jeen-Woo Informa Healthcare 2007 Free radical research Vol.41 No.6
<P> A high concentration of glucose has been implicated as a causal factor in initiation and progression of diabetic complications and there is evidence to suggest that hyperglycemia increases the production of free radicals and oxidative stress. Therefore, compounds that scavenge reactive oxygen species (ROS) may confer regulatory effects on high glucose-induced apoptosis. Ursolic acid (UA), a pentacyclic triterpene, is reported to have an antioxidant activity. We investigated the effect of UA on high glucose-induced apoptosis in U937 cells. Upon exposure to 35 mM glucose for two days, there was a distinct difference between untreated cells and cells pre-treated with 50 nM UA for 2 h in regard to cellular redox status and oxidative DNA damage to cells. UA pre-treated cells showed significant suppression of apoptotic features such as DNA fragmentation, damage to mitochondrial function and modulation of apoptotic marker proteins upon exposure to high glucose. This study indicates that UA may play an important role in regulating the apoptosis induced by high glucose presumably through scavenging of ROS.</P>
AN IMPROVED BABY-STEP-GIANT-STEP METHOD FOR CERTAIN ELLIPTIC CURVES
OH, BYEONG-KWEON,HA, KIL-CHAN,OH, JANGHEON 한국전산응용수학회 2006 Journal of applied mathematics & informatics Vol.20 No.1
In this paper, we slightly improve the Baby-step Giant-step for certain elliptic curves. This method gives the running time improvement of $200\%$ in precomputation (Baby-step) and requires half as much storage as the original Baby-step Giant-step method.
Effect of Plant Density on Growth and Sugar Yield of Sweet Sorghum in Jeju Island
Oh, Hyeon-Do,Kim, Han-Lim,Kang, Young-Kil,Kim, Chan-Woo The Korean Society of Crop Science 2001 Korean journal of crop science Vol.46 No.1
A sweet sorghum [Sorghum bicolor (L.) Moench] cultivar was planted on 9 and 30 June 2000 at plant densities of 4, 6, 8, 10, and 12 plants $m^{-2}$ to determine the optimum plant density in Jeju region. There were no significant planting date x plant density interactions for most traits measured. Delaying planting from 9 to 30 June delayed 21 days in heading date, and significantly decreased plant height, the number of productive stems $m^{-2}$/, and lodging. Fresh stem yield tended to be higher at the 9 June planting date than at the 30 June planting date, but total sugar and ethanol yields were not significantly affected by planting date. Percentage of soluble solid was higher at the 30 June planting date compared with the 9 June planting date. Fresh stem, total sugar, and ethanol yields quadractically increased from 22.9 to 36.7 $t^{-1}$, from 1.66 to 2.54 $t^{-1}$, and from 945 to 1440 $L^{-1}$, respectively, with increasing plant density. The optimal plant densities for the maximum fresh stem, total sugar, and ethanol were estimated to be 10.7, 9.6, and 9.9 plants $m^{-2}$ respectively.
Control effect of thrips by using two-fluid fogging system on red pepper in greenhouse
Oh-hun Kwon,Kil-su Jang,Chan-yong Kim,Na-yun Park,Mirina Lee,Jong-gun Won,Hee-young Jung 한국응용곤충학회 2019 한국응용곤충학회 학술대회논문집 Vol.2019 No.04
고추 비가림하우스에서 에어포그 시스템을 이용한 무인방제 효과를 평가하기 위해 본 시험을 수행하였다. 에어포그 시스템과 동력분무기를 이용한 관행방제의 약제살포 시간은 동일한 약량으로 살포하였을 때 처리 간에 차이가 없었으나, 에어포그 시스템으로 1/2약량을 살포하였을 때는 관행방제 보다 살포시간이 약 50% 줄었다. 약제부착 능력을 감수지로 조사하였을 때, 고추 생육초기와 중기에는 모든 처리에서 약제 부착이 우수 하였지만, 생육후기에는 관행방제의 약제 부착이 에어포그 시스템보다 균일하지 않았다. 처리별 총채벌레 살충률은 관행살포 90.0%, 에어포그 시스템 90.8%, 에어포그 시스템 1/2약량이 83.5% 로 유사한 방제효과를 나타내었다. 이러한 결과로 에어포그 시스템은 고추 비가림하우스 내에서 노동시간과 약제 살포량을 줄이면서 총채벌레를 효과적으로 방제할 수 있을 것으로 판단된다.