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Magcalas Ken Jeffrey,Oe Shin,Yamato Yu,Hasegawa Tomohiko,Yoshida Go,Banno Tomohiro,Arima Hideyuki,Mihara Yuki,Ushirozako Hiroki,Yamada Tomohiro,Ide Koichiro,Watanabe Yuh,Matsuyama Yukihiro 대한척추외과학회 2023 Asian Spine Journal Vol.17 No.2
Study Design: Cohort study.Purpose: There is currently no published study that focuses on the spinal corrective surgery effects with cranial parameters in adult spinal deformity (ASD) patients. It is an important factor to measure since it plays a critical role in maintaining the line of sight. The objective is to determine the change in cranial parameters using the slope of McGregor’s line (McGS) after ASD surgery after 2 years of follow-up.Overview of Literature: A study concluded that cervical spine alignment (C2–C7 lordosis) is strongly affected by thoracic kyphosis (TK). Another study showed that patients with ascending gaze had significantly more thoracolumbar malalignment.Methods: This retrospective study includes 295 corrective surgery patients with ASD. Subjects were divided into two groups after propensity age matching analysis: cranial malalignment (McGS <−8 or >13) and normal cranial alignment (−8≤ McGS ≤13). Lumbar lordosis (LL), pelvic tilt (PT), TK, cervical lordosis (CL), and sagittal vertical axis (SVA) were evaluated between the two groups.Results: SVA (95–56 mm) and PT (34°–25°) decreased and LL (19°–41°) increased 2 years after surgery (p <0.05), but McGS (−1.1° to −0.5°) and CL (21°–19°) did not change. Conversely, in the group with cranial malalignment, SVA (120–64 mm), PT (35°–26°), and LL (12°–41°) showed similar results to the normal cranial parameter group 2 years after surgery, but in contrast, McGS (−13° to −2°) and CL (24°–18°) improved significantly.Conclusions: Severe ASD adversely affects to maintain horizontal gaze but can be improved by spinal corrective surgery.
Suto Hitoshi,Matsuyama Ken,Hattori Yasuo 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.8
When evaluating energy balance and temperature in reduced-scale fire experiments, which are conducted as an alternative to full-scale fire experiments, it is important to consider the similarity in the scale among these experiments. In this paper, a method considering the similarity of energy balance is proposed for setting the conditions for reduced-scale experiments of mechanically ventilated compartment fires. A small-scale fire experiment consisting of various cases with different compartment geometries (aspect ratios between 0.2 and 4.7) and heights of vents and fire sources was conducted under mechanical ventilation, and the energy balance in the quasi-steady state was evaluated. The results indicate the following: (1) although the compartment geometry varies the energy balance in a mechanically ventilated compartment, the variation in the energy balance can be evaluated irrespective of the compartment size and geometry by considering scaling factor F (∝heffAwRT, where heff is the effective heat transfer coefficient, Aw is the total wall area, and RT is the ratio of the spatial mean gas temperature to the exhaust temperature); (2) the value of RT, which is a part of F, reflects the effects of the compartment geometry and corresponds to the distributions of the gas temperature and wall heat loss
Rapid measurements of hydrogen cyanide concentration in combustion gas via terahertz spectroscopy
Araki Mitsunori,Matsuyama Ken 한국물리학회 2022 Current Applied Physics Vol.36 No.-
The development of a real-time measurement system to determine the concentrations of combustion gases mixed with smoke particles in fire environments is an essential technical issue in the fire safety field. In this study, the absorption line for the J = 8–7 rotational transition at 708.9 GHz of hydrogen cyanide (HCN) produced by the combustion of silk is rapidly measured in a 1 m cell during repeat scans (seven times a minute) via terahertz spectroscopy. The obtained time profile of HCN concentrations agrees well with the time profile obtained via Fourier transform infrared (FT-IR) spectroscopy. The maximum concentrations derived via terahertz spectroscopy are consistent with those derived via FT-IR within an accuracy of 10%. The minimum sensitivity of HCN is 100 ppm as detected via terahertz spectroscopy. The repetition rate, the accuracy, and the sensitivity for the scans demonstrate the potential of terahertz spectroscopy to rapidly diagnose combustion gas flow concentrations in fire environments.
초기화재시 스프링클러 작동에 따른 Smoke-logging현상에 관한 실험적 연구
윤웅기(Unggi Yoon),구인혁(Inhyuk Koo),마츠야마 켄(Matsuyama,Ken ),권영진(Youngjin Kwon) 한국방재학회 2023 한국방재학회논문집 Vol.23 No.6
본 연구에서는 합리적인 피난안전성을 평가하기 위한 기초자료를 구축하고자, 초기화재시 스프링클러작동에 따른 스모크-로깅(Smoke-logging)현상에 대해 고찰하였다. 스프링클러(Sprinkler) 및 워터미스트(Water Mist) 헤드별 분무액적특성(살수 물방울의 입경, 입속, 분포 등)을 실험적으로 고찰하였으며, 화원의 종류(Ethanol, Polyurethane) 및 헤드별에 따른 구획 내 연기 층의 하강기류를 분석하고, 이를 바탕으로 기존연구에서 제시된 연기하강기류 예측 식을 이용하여 회귀 식을 도출하였다. This study establishes basic data for the reasonable evaluation of evacuation safety and investigates the smoke-logging phenomenon owing to the operation of sprinklers during the initial fire. The spray droplet characteristics of a sprinkler and water mist head were examined, and the descending air current of the smoke layer was analyzed according to the type of fire source (ethanol, polyurethane) and head. A regression equation based on the findings was derived using the prediction equation for the descending air current of the smoke layer presented in a previous study.