http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Image-Based Markers Predict Dynamic Instability in Lumbar Degenerative Spondylolisthesis
William Slikker III,Alejandro A. Espinoza Orías,Grant D. Shifflett,Joe Y.B. Lee,Krzysztof Siemionow,Sapan Gandhi,Louis Fogg,Dino Samartzis,Nozomu Inoue,Howard S. An 대한척추신경외과학회 2020 Neurospine Vol.17 No.1
Objective: To identify possible radiographic predictors markers of dynamic instability including disc height (DH), disc degeneration, and spondylosis in the setting of degenerative spondylolisthesis (DS). Methods: A retrospective review with prospectively collected data was performed on 125 patients with L4–5 DS who underwent decompression and fusion. Patients were divided into groups with dynamic instability and those without. Radiographs of the lumbar spine in neutral, flexion, and extension were used to determine degree of slip, DH, translational motion, angular motion, spondylotic changes, and lumbar lordosis. Magnetic resonance imaging (MRI) scans were reviewed to assess disc degeneration. Results: Thirty-one percent of the patients met criteria for dynamic instability. Significant correlations (p<0.05) were found between preserved DH and dynamic instability; increased spondylotic changes and decreased translational motion; as well as advanced MRI-based disc degeneration scores with decreased angular motion, respectively. Six radiographic parameters were utilized to create a predictive model for dynamic instability, and a receiver operating characteristic curve was able to validate the predictive model (area=0.891, standard error=0.034, p<0.001). Conclusion: In DS patients, preserved DH was significantly related to dynamic instability. This finding may represent a greater potential for slip progression over time in these patients. In contrast, disc degeneration on MRI, and spondylotic changes were inversely related to dynamic instability and may represent restabilization mechanisms that decrease the chance of future slip progression in DS.
저탄소강 (Fe-0.06%C 강) 아크 분무 성형체의 액적 경계면 합체 분율 예측
이재철,이호인,석현광,Grant, Patrick S . 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.8
During the electric arc spray forming(EASF) including Osprey forming, thermal spray forming and plasma spray forming, critical is the thermal condition of the deposit, especially at the deposition domain (footprint), where droplets impinge on a substrate or surface to form a deposit. Many experimentals show that the microstructure of the deposit depends on the thermal conditions at the footprint. In thin paper, microscopic model was presented to describe the splat boundary coalescence at the footprint, which estimates the fractional quantity of splat boundary coalescence at the footprint under the assumptions of average droplet size impinging on the deposit surface. This model was adopted to describe the microstructural evolution of the Fe-0.06%C steel ring EAS formed with a law substrate rotation velocity. The contents of splat boundary coalescence of the deposit, EAS formed on the substrate with a high rotation velocity or on the stationary substrate, were also estimated using the quantitative model.
이재철,이호인,석현광,Grant, Patrick S . 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.8
Critical to the electric arc spray forming(EASF) including Osprey forming and plasma spray forming is the thermal condition of the deposit, which determines the microstructure and mechanical properties of the deposits. In the EASF of Fe-0.06%C steel ring, the microhardness of the deposit varied in the range from 160 through 230 Hv(0.2) with various EASF conditions. It was found out that the microhardness of the deposit was closely connected with the thermal condition of the deposit. Temperature profiles in an EAS formed ring of low carbon steel(Fe-0.06%C) has been calculated by using a growth model based on the vector calculus and heat transfer model based on the body fitted coordinate method. The effects of EASF parameters such as substrate rotation velocity, droplet flow rate and average droplet temperature on the preform temperature profile were investigated. The calculation results were compared with experimentals. Fe-0.06%C steel was arc-melted and sprayed onto a rotating tubular steel substrate. During spray forming, the surface temperature of the deposit was measured using an infrared thermal imaging camera that was accurately calibrated. The effect of deposition temperature on the deposit microstructure was also investigated. The calculation results showed a good agreement with experimental results.