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Ban, Seung Pil,Kwon, O-Ki,Kim, Young Deok,Kim, Bum-Tae,Oh, Jae Sang,Kim, Kang Min,Kim, Chang Hyeun,Kim, Chang-Hyun,Choi, Jai Ho,Kim, Young Woo,Lim, Yong Cheol,Byoun, Hyoung Soo,Park, Sukh Que,Chung, J The Korean Neurosurgical Society 2022 Journal of Korean neurosurgical society Vol.65 No.6
Objective : Stent-assisted coil embolization (SAC) has been increasingly used to treat various types of intracranial aneurysms. Delayed thromboembolic complications are major concerns regarding this procedure, so dual antiplatelet therapy with aspirin and clopidogrel is needed. However, clinicians vary the duration of dual antiplatelet therapy after SAC, and no randomized study has been performed. This study aims to compare the safety and efficacy of long-term (12 months) dual antiplatelet therapy and short-term dual antiplatelet therapy (6 months) after SAC for patients with unruptured intracranial aneurysms (UIAs). Methods : This is a prospective, randomized and multicenter trial to investigate the optimal duration of dual antiplatelet therapy after SAC in patients with UIAs. Subjects will receive dual antiplatelet therapy for 6 months (short-term group) or 12 months (long-term group) after SAC. The primary endpoint is the assessment of thromboembolic complications between 1 and 18 months after SAC. We will enroll 528 subjects (264 subjects in each group) and perform 1 : 1 randomization. This study will involve 14 top-performing, high-volume Korean institutions specializing in coil embolization. Results : The trial will begin enrollment in 2022, and clinical data will be available after enrollment and follow-up. Conclusion : This article describes that the aim of this prospective randomized multicenter trial is to compare the effect of short-term (6 months) and long-term (12 months) dual antiplatelet therapy on UIAs in patients undergoing SAC, and to find the optimal duration.
Si-Cr 스프링 강에서의 Mo 및 W 첨가가 미세조직 및 기계적 성질에 미치는 영향
남원종,이상래,반덕영 대한금속재료학회(대한금속학회) 1998 대한금속·재료학회지 Vol.36 No.2
Effects of the Mo and W additions to Si-Cr spring steels on the microstructural evolution and mechanical properties in spring steels were investigated. It was found that the Mo and/or W addition does not change the behavior of tempered carbide at low temperatures, such as the precipitation of ε-carbide and the conversion of ε-carbide to cementite, via dilatometry tests and the observation of microstructure using TEM. However, it would reduce the coarsening rate of cementite at high temperatures above 450℃, resulting in the smaller size of cementite particles due to the lower diffusion rate. Since the sag resistance depends on the distribution and the size of precipitates, steel C(0.2% W) showed the strongest sag resistance whereas steel A showed the weakest sag resistance, when tempered at 450℃. Also, an abundance of precipitates at 350℃ tempering exhibits the maximum loop area, i.e., the sag resistance for all the tested steels. The Mo and W additions to Si-Cr spring steels raised the ratio of loop area/tensile strength. Therefore, the Mo and W additions would be effective method to increase the sag resistance as well as strength in Si-Cr spring steels.
W의 첨가가 고강도 Si-Cr 스프링 강의 미세 조직 및 기계적 성질에 미치는 영향
남원종,이상래,반덕영 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.8
Effects of the W addition on the microstructure evolution and mechanical properties of high strength Si-Cr spring steels have been investigated. The W addition would reduce the coarsening rate of cementite due to the lower diffusion rate, resulting in a smaller size of cementite particles. The sag resistance depends on the distribution and the size of precipitates. Therefore, an abundance of precipitates at 350℃ tempering exhibits the maximum hysteresis loop area, i.e. the sag resistance. At the tempering temperature of 450℃-500℃, the W addition resulted in the improvement of the sag resistance through the suppression of the cementite coarsening.
Lee Sang Hyo,Lee Si Un,Kwon O-Ki,Bang Jae Seung,Ban Seung Pil,Kim Tackeun,Kim Young Deok,Byoun Hyoung Soo,Oh Chang Wan 대한의학회 2021 Journal of Korean medical science Vol.36 No.26
Background: We aimed to analyze outcomes of clipping and coiling in treating unruptured intracranial aneurysms (UIAs) in elderly patients and to identify the age at which perioperative risk increases based on national cohort data in South Korea. Methods: The incidence of perioperative intracranial hemorrhage (ICRH), perioperative cerebral infarction (CI), mortality, and moderate to severe disability data of the patients who underwent coiling or clipping for UIAs were retrieved. Estimated breakpoint (EBP) was calculated to identify the age at which the risk of treatment increases. Results: A total of 38,207 patients were treated for UIAs. Among these, 22,093 (57.8%) patients underwent coiling and 16,114 (42.2%) patients underwent clipping. The incidence of ICRH, requiring a secondary operation, within 3 months in patients ≥ 65 years that underwent coiling and clipping was 1.13% and 4.81%, respectively, and that of both groups assessed were significantly higher in patients ≥ 75 years (coiling, P = 0.013, relative risk (RR) 1.81; clipping, P = 0.015) than younger patients. The incidence of CI within 3 months in patients aged ≥ 65 was 13.90% and 9.19% in the coiling and clipping groups, respectively. The incidence of CI after coiling in patients aged ≥ 75 years (P < 0.001, RR 1.96) and after clipping in patients aged ≥ 70 years (P < 0.001, RR 1.76) was significantly higher than that in younger patients. The mortality rates within 1 year in patients with perioperative ICRH or CI were 2.41% and 3.39% for coiling and clipping groups, respectively, in patients ≥ 65. These rates increased significantly at age 70 in the coiling group and at age 75 for the clipping group (P = 0.012 and P < 0.001, respectively). Conclusion: The risk of treatment increases with age, and this risk increases dramatically in patients aged ≥ 70 years. Therefore, the treatment decisions in patients aged ≥ 70 years should be made with utmost care.
Seo, Dongwook,Lee, Si Un,Oh, Chang Wan,Kwon, O-Ki,Ban, Seung Pil,Kim, Tackeun,Byoun, Hyoung Soo,Kim, Young Deok,Lee, Yongjae,Won, Yu Deok,Bang, Jae Seung The Korean Neurosurgical Society 2019 Journal of Korean neurosurgical society Vol.62 No.6
Objective : To analyze the angiographic features and clinical course, including treatment outcomes and the natural course, of fusiform middle cerebral artery aneurysms (FMCAAs) according to their location, size, and configuration. Methods : We reviewed the literature on adult cases of FMCAAs published from 1980 to 2018; from 25 papers, 112 FMCAA cases, for which the location, size, and configuration could be identified, were included in this study. Additionally, 33 FMCAA cases in our hospital were included, from which 16 were assigned to the observation group. Thus, a total of 145 adult FMCAA cases were included. We classified the FMCAAs according to their location (l-type 1, beginning from prebifurcation; l-type 2, beginning from bifurcation; l-type 3, beginning from postbifurcation), size (small, <10 mm; large, ${\geq}10mm$; giant, ${\geq}25mm$), and configuration (c-type 1, classic dissecting aneurysm; c-type 2, segmental ectasia; c-type 3, dolichoectatic dissecting aneurysm). Results : The c-type 3 was more commonly diagnosed with ischemic symptoms (31.8%) than hemorrhage (13.6%), while 40.9% were found accidentally. In contrast, c-type 2 was more commonly diagnosed with hemorrhagic symptoms (14.9%) than ischemic symptoms (10.6%), and 72.3% were accidentally discovered. According to location, ischemic symptoms and hemorrhage were the most frequent symptoms in l-type 1 (28.6%) and l-type 3 (34.6%), respectively. Most of l-type 2 FMCAAs were found incidentally (68.4%). Based on the size of FMCAAs, only 11.1% of small aneurysms were found to be hemorrhagic, while 18.9% and 26.0% of large and giant aneurysms were hemorrhagic, respectively. Although four aneurysms of the 16 FMCAAs in the observation group increased in size and one aneurysm decreased in size during the observation period, no rupture was seen in any case and there were no significant predictors of aneurysm enlargement. Of 104 FMCAAs treated, 14 cases (13.5%) were aggravated than before surgery and all the aggravated cases were l-type 1. Conclusion : While ischemic symptoms occurred more frequently in l-type 1 and c-type 3, hemorrhagic rather than ischemic symptoms occurred more frequently in l-type 3 and c-type 2. In case of l-type 1 FMCAAs, more caution is required in determining the treatment due to the relatively high complication rate.
고탄소강 다단 신선 와이어의 표면 온도 상승에 의한 축방향 잔류응력 예측
김대운(Dae Woon Kim),이상곤(Sang Kon Lee),김병민(Byung Min Kim),정진영(Jin Young Jung),반덕영(Deok Young Ban) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.10
최근 와이어의 생산성 및 고강도화를 위한 고탄소강의 고속신선으로 인해 와이어 표면의 급격한 온도상승으로 잔류응력이 크게 증가하는 문제점이 발생되고 있다. 와이어의 다단 신선 공정시에는 소성변형과 마찰열에 의하여 와이어 내부의 온도가 더욱 크게 상승하게 된다. 특히, 고속 신선의 경우 마찰에 의한 온도구배가 더욱 크게 되어 와이어 표면층에 축방향 인장 잔류응력을 과도하게 발생시킨다. 따라서, 본 연구에서는 먼저 표면 온도 상승과 축방향 잔류응력과의 관계를 규명한 다음에 와이어의 평형온도 예측 모델을 제안하고, 이를 토대로 표면 온도 상승에 의한 축방향 잔류응력 예측식을 개발하였다. 고탄소강(0.82%C)소재의 다단신선 실험을 통해 얻어진 시편에 대하여 X 선 회절을 이용하여 잔류응력을 측정하여 제안된 예측식을 검증하였다. In recent times, due to wire drawing of high carbon steel at a high speed to ensure a high productivity and high strength, axial residual stress are generated because of rapid increase in surface temperature. In the process, the temperatures of the wires increased because of the deformation of the wires and the friction between the die and wire. In particular, in the case of the wire drawing at a high speed, friction leads to a large temperature gradient so that considerable axial residual stress is generated on the surface. In this study, the relationship between axial residual stress and increase in the surface temperature was investigated, and a prediction model of uniform temperature was proposed. Then, a prediction model for residual stress was developed. The proposed model was verified by measuring the residual stress by X-ray diffraction on drawn wires.
Fabrication of a bionic superhydrophobic metal surface by sulfur-induced morphological development
Han, Joong Tark,Jang, Yunseok,Lee, Dong Yun,Park, Ji Hwan,Song, Seong-Hun,Ban, Deok-Young,Cho, Kilwon Royal Society of Chemistry 2005 Journal of materials chemistry Vol.15 No.30
<P>We describe the fabrication of lotus leaf-like superhydrophobic metal surfaces by using the simple electrochemical reaction of Cu or Cu–Sn alloy plated on steel sheets with sulfur gas, and subsequent perfluorosilane treatment. The microstructure of these surfaces was obtained through the nonelectric chemical plating of the copper onto the steel sheets, and the nanotexturing of the surfaces was achieved <I>via</I> an electrochemical reaction of copper in a sulfur-containing environment at 150 °C, resulting in the formation of a copper sulfide nanostructure on the microstructure. The chemical composition of this metal surface was confirmed using X-ray photoelectron spectroscopy. The water contact angles of the bionic metal surfaces were found to be over 160°, and this surface exhibits a low contact angle hysteresis. To our knowledge, this is the first time this approach has been used with a simple chemical reaction to fabricate an artificial superhydrophobic metal surface.</P> <P>Graphic Abstract</P><P>Bionic superhydrophobic metal surfaces have been created by plating a steel surface with Cu or Cu–Sn alloy, followed by sulfur gas treatment, and the hydrophobization of the surface. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b504850h'> </P>