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Baek Jang-Hyun,Kim Byung Moon,Suh Sang Hyun,Jeon Hong-Jun,Ihm Eun Hyun,Park Hyungjong,Kim Chang-Hyun,Cha Sang-Hoon,Choi Chi-Hoon,Yi Kyung Sik,Kim Jun-Hwee,Suh Sangil,Kim Byungjun,Chang Yoonkyung,Kim S 대한영상의학회 2023 Korean Journal of Radiology Vol.24 No.2
Objective: We aimed to evaluate the efficacy of EmboTrap II in terms of first-pass recanalization and to determine whether it could yield favorable outcomes. Materials and Methods: In this multicenter, prospective study, we consecutively enrolled patients who underwent mechanical thrombectomy using EmboTrap II as a front-line device. The primary outcome was the first pass effect (FPE) rate defined by modified Thrombolysis In Cerebral Infarction (mTICI) grade 2c or 3 by the first pass of EmboTrap II. In addition, modified FPE (mFPE; mTICI grade 2b–3 by the first pass of EmboTrap II), successful recanalization (final mTICI grade 2b–3), and clinical outcomes were assessed. We also analyzed the effect of FPE on a modified Rankin Scale (mRS) score of 0–2 at 3 months. Results: Two hundred-ten patients (mean age ± standard deviation, 73.3 ± 11.4 years; male, 55.7%) were included. Ninetynine patients (47.1%) had FPE, and mFPE was achieved in 150 (71.4%) patients. Successful recanalization was achieved in 191 (91.0%) patients. Among them, 164 (85.9%) patients underwent successful recanalization by exclusively using EmboTrap II. The time from groin puncture to FPE was 25.0 minutes (interquartile range, 17.0–35.0 minutes). Procedure-related complications were observed in seven (3.3%) patients. Symptomatic intracranial hemorrhage developed in 14 (6.7%) patients. One hundred twenty-three (58.9% of 209 completely followed) patients had an mRS score of 0–2. Sixteen (7.7% of 209) patients died during the follow-up period. Patients who had successful recanalization with FPE were four times more likely to have an mRS score of 0–2 than those who had successful recanalization without FPE (adjusted odds ratio, 4.13; 95% confidence interval, 1.59–10.8; p = 0.004). Conclusion: Mechanical thrombectomy using the front-line EmboTrap II is effective and safe. In particular, FPE rates were high. Achieving FPE was important for an mRS score of 0–2, even in patients with successful recanalization.
Sangil Hyun,주재황,강기주 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.4
The Kagome truss has been attracting attention, because it has equivalent or even higher strength compared to the octet truss with the same material and density. In this work, another aspect, which seems to be important for its practical applications, that is, defect sensitivity of bulk PCMs (periodic cellular metals) composed of Kagome trusses to mechanical behaviors subjected to compression was compared with a counterpart composed of octet trusses. In order to investigate the mechanical characteristics of bulk PCMs composed of the two trusses, a hybrid approach was taken in this work. First, assuming perfectly uniform structure and deformation of WBK, the behavior of the bulk PCMs composed of infinite number of trusses was simulated by finite element analysis for a unit cell with periodic boundary conditions. From the results, the force-displacement response of a single strut composing the trusses in each bulk PCM was estimated. Then, the effects of geometric imperfections and the inhomogeneous material properties were evaluated by network analyses, in which the force-displacement responses were used to characterize mechanical behaviors of the networks. The imperfections were modeled to have Gaussian distributions, and the analysis results of the two bulk PCMs were compared to evaluate their defect sensitivities. For the geometric imperfections, the maximum strength of both bulk PCMs decreased gradually as the imperfection level increased. For material property imperfections, the maximum strength maintained nearly unchanged for the PCM composed of Kagome trusses. On the other hand, for that composed of octet trusses, it slightly dropped as the imperfection level increased. The octet truss PCM was found to be more sensitive to the property imperfections than the other.
옥테트와 카고메 트러스 구조를 갖는 벌크형 PCM의 압축거동
현상일(Sangil Hyun),주재황(Jai-Hwang Joo),강기주(Ki-Ju Kang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Defect sensitivity of bulk PCMs (periodic cellular metals) composed of Kagome trusses to mechanical behaviors subjected to compression was compared with a counterpart composed of octet trusses. To investigate the mechanical characteristics of bulk PCMs composed of the two trusses, a hybrid approach was taken in this work. First, assuming perfectly uniform structure and deformation of bulk PCMs, the behavior of the bulk PCMs composed of infinite number of trusses was simulated by FE analysis for a unit cell with periodic boundary conditions. From the results, the force-displacement response of a single strut composing the trusses in each bulk PCM was estimated. Then, the effects of geometric imperfections and the inhomogeneous material properties were evaluated by network analyses, in which the force-displacement responses were used to characterize mechanical behaviors of the networks. The imperfections were modeled to have Gaussian distributions, and the analysis results of the two bulk PCMs were compared to evaluate their defect sensitivities. Consequently, the bulk PCMs composed of octet trusses were found to be more sensitive to the property imperfections than those of Kagome trusses.
현상일(Sangil Hyun),박영호(Youngho Park),강기주(Ki-Ju Kang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
A cellular material based on kagome lattice is an ideal candidate for a multifunctional material. Due to its superior mechanical performance under external loads, it is considered to possess optimal stability in structural applications. In previous studies however the analysis has been performed mostly for static properties. The evaluation of dynamic characteristics of kagome materials would be a key issue for its more general applications. In this talk, we present a numerical simulation result on the mechanical performance of the kagome structures under various dynamic external loads such as impacts and vibrations. Defect sensitivities of the dynamic responses were determined using eigenmode analysis and molecular dynamics simulations.
현상일(Sangil Hyun),최지은(Ji-Eun Choi),강기주(Ki-Ju Kang) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
A newly developed cellular metal based on kagome lattice is an ideal candidate for multifunctional materials achieving various optimal properties. Intensive efforts have been devoted to develop efficient techniques for mass production due to its wide potential applications. Since a variety of imperfections would be inevitably included in the realistic fabrication processes, it is highly important to examine the correlation between the imperfections and material strengths. Previous performance tests were mostly done by numerical simulations such as finite element method (FEM), but only for perfect structures without any imperfection. In this paper, we developed an efficient numerical framework using nonlinear random network analysis (RNA) to verify how the statistical imperfections (geometrical and material property) contribute to the performance of general truss structures. The numerical results for kagome truss structures are compared with experimental measurements on 3-layerd WBK (wire-woven bulk kagome). The mechanical strength of the kagome structures is shown relatively stable with the Gaussian types of imperfections.
현상일(Sangil Hyun),전재성(Jae Sung Jeon),김영석(Young-Suk Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Finite-element methods are used to study non-adhesive, frictionless rough contact of elastic and plastic solids. Roughness on spherical surfaces is realized by self-affine fractal. True contact area between the rough surfaces and nat rigid surfaces increases with power law under external normal loads. The power exponent is sensitive to surface roughness as well as the curvature of spherical geometry. Surface contact pressures are analyzed and compared for the elastic and plastic solids. Distributions of local contact pressure are shown dependent on the surface roughness and the yield stress of plastic solids.
곡선구간에서의 전차선 편마모 개선을 위한 강체전차선 시스템 브래킷 개발
이상일(Sangil Lee),장광동(Kwang Dong Jang),배상준(Sangjoon Bae),김현웅(Hyun Woong Kim),김진우(Jin Woo Kim) 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.5
터널 및 지하구간의 곡선구간에서는 안전한 운행을 위해 캔트(cant)가 적용된다. 이때 기울어진 철도차량 판토그래프의 습동판과 강체전차선(R-BAR)이 기울어진 채 접촉하게 되며 전차선 편마모(side wear)가 발생, 교체주기가 단축돼 유지보수 비용이 상승하게 된다. 본 개발에서는 곡선구간에서 전차선의 편마모를 저감할 수 있는 경사조정형 브래킷 개발과 상호호환성에 대해 검증하였다.