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- 저자 : Atsushi Nishiyama (검색결과 10 건)
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Influences of hard- and soft- segment ratios on pyrolysis behavior of polyurethane elastomers
( Yuya Nishiyama ),( Shogo Kumagai ),( Tomohito Kameda ),( Yuko Saito ),( Atsushi Watanabe ),( Suguru Motokucho ),( Hisayuki Nakatani ),( Toshiaki Yoshioka ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 한국폐기물자원순환학회 심포지움 Vol.2019 No.1
Introduction Polyurethane elastomers (PUEs) are typical block copolymers which are composed of alternative hard segment (HS) and soft segment (SS), with the physical and chemical properties of them can be varied by changing HS and SS ratios. Pyrolysis is a promising method for polymeric wastes recycling because it can convert various polymers into chemical feedstock only by heat1). In this study, seven kinds of PUEs with different HS and SS ratios were synthesized (Fig. 1), then influences of hard- and soft-segment ratios on pyrolysis behavior were investigated. Methods, Results and discussion 1. Identification of pyrolysis products: Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to characterize the pyrolysis products under elevated temperature shown in Fig. 2. All the PUEs produced MDI, MAI and MDA (Fig. 3) from HS through pyrolysis, which were formed by pyrolytic urethane bond cleavage via 4-membered and 6-membered transition states shown in Scheme1. 2. In-situ monitoring of ticpyrolysis products: In-situ monitoring of pyrolysis products, called evolved gas analysis-MS (EGA-MS), was performed under the same pyrolysis conditions as the previous section. EGA chromatogram and representative products are shown in Fig. 4. Pyrolysis of various PUEs with different HS and SS clearly showed presence of three pyrolysis zones. In the zone 1, HS decomposition products such as CO<sub>2</sub>, butanediol (BD) and MDI are generated from five PUEs having HS. This suggested that formation of isocyanate end shown in Scheme1-I was dominant at this temperature. In the zone 2, SS-derived products and CO<sub>2</sub> were mainly formed from the five PUEs with low HS ratios. MDI was not produced in this zone, while MAI and MDA were produced. These results revealed that the high temperature promoted formation of the amine end shown in Scheme1-Ⅱ. In addition, a part of the SS-derived product could be generated by decomposition of MDI between HS and SS. In the zone 3, SS-derived products were produced from all PUEs, and the SS decomposition was continued. Thus, the temperature-dependent pyrolysis behavior was proposed (Scheme2) based on the findings in this work. Conclusion Temperature-dependent pyrolysis behavior of PUEs with different hard- and soft-segment ratios was investigated through pyrolysis tests employing Py-GC/MS and EGA-MS techniques. The findings in this work will be helpful to control product selectivity and feedstock recovery through pyrolytic approach.
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Muscle Functional MRI of Exercise-Induced Rotator Cuff Muscles
Tawara, Noriyuki,Nishiyama, Atsushi Korean Society of Magnetic Resonance in Medicine 2021 Investigative Magnetic Resonance Imaging Vol.25 No.1
The aim of this study was to provide a new assessment of rotator cuff muscle activity. Eight male subjects (24.7 ± 3.2 years old,171.2 ± 9.8 cm tall, and weighing 63.8 ± 11.9 kg) performed the study exercises. The subjects performed 10 sets of the exercise while fixing the elbow at 90 degrees flexure and lying supine on a bed. One exercise set consisted of the subject performing external shoulder rotation 50 times using training equipment. Two imaging protocols were employed: (a) true fast imaging with steady precession (TrueFISP) at an acquisition time of 12 seconds and (b) multi-shot spin-echo echo-planar imaging (MSSE-EPI) at an acquisition time of 30 seconds for one echo. The main method of assessing rotator cuff muscle activity was functional T2 mapping using ultrafast imaging (fast-acquired muscle functional MRI [fast-mfMRI]). Fast-mfMRI enabled real-time imaging for the identification and evaluation of the degree of muscle activity induced by the exercise. Regions of interest were set at several places in the musculus subscapularis (sub), musculus supraspinatus (sup), musculus teres minor (ter), and deltoid muscle (del). We used the MR signal of the images and transverse relaxation time (T2) for comparison. Most of the TrueFISP signal was not changed by exercise and there was no significant difference from the resting values. Only the T2 in the musculus teres minor was increased after one set and the change were seen on the T2 images. Additionally, except for those after one and two sets, the changes in T2 were significant compared to those at rest (P < 0.01). We also demonstrated identify and visualize the extent to which muscles involved in muscle activity by exercise. In addition, we showed that muscle activity in a region such as a shoulder, which is susceptible to B0 inhomogeneity, could be easily detected using this technique.
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Effect of Number of Measurement Points on Accuracy of Muscle T2 Calculations
Tawara, Noriyuki,Nishiyama, Atsushi Korean Society of Magnetic Resonance in Medicine 2016 Investigative Magnetic Resonance Imaging Vol.20 No.4
Purpose: The purpose of this study was to investigate the effect of the number of measurement points on the calculation of transverse relaxation time (T2) with a focus on muscle T2. Materials and Methods: This study assumed that muscle T2 was comprised of a single component. Two phantom types were measured, 1 each for long ("phantom") and short T2 ("polyvinyl alcohol gel"). Right calf muscle T2 measurements were conducted in 9 healthy male volunteers using multiple-spin-echo magnetic resonance imaging. For phantoms and muscle (medial gastrocnemius), 5 regions of interests were selected. All region of interest values were expressed as the mean ${\pm}$ standard deviation. The T2 effective signal-ratio characteristics were used as an index to evaluate the magnetic resonance image quality for the calculation of T2 from T2-weighted images. The T2 accuracy was evaluated to determine the T2 reproducibility and the goodness-of-fit from the probability Q. Results: For the phantom and polyvinyl alcohol gel, the standard deviation of the magnetic resonance image signal at each echo time was narrow and mono-exponential, which caused large variations in the muscle T2 decay curves. The T2 effective signal-ratio change varied with T2, with the greatest decreases apparent for a short T2. There were no significant differences in T2 reproducibility when > 3 measurement points were used. There were no significant differences in goodness-of-fit when > 6 measurement points were used. Although the measurement point evaluations were stable when > 3 measurement points were used, calculation of T2 using 4 measurement points had the highest accuracy according to the goodness-of-fit. Even if the number of measurement points was increased, there was little improvement in the probability Q. Conclusion: Four measurement points gave excellent reproducibility and goodness-of-fit when muscle T2 was considered mono-exponential.
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Effect of Number of Measurement Points on Accuracy of Muscle T2 Calculations
Noriyuki Tawara,Atsushi Nishiyama 대한자기공명의과학회 2016 Investigative Magnetic Resonance Imaging Vol.20 No.4
Purpose: The purpose of this study was to investigate the effect of the number of measurement points on the calculation of transverse relaxation time (T2) with a focus on muscle T2. Materials and Methods: This study assumed that muscle T2 was comprised of a single component. Two phantom types were measured, 1 each for long (“phantom”) and short T2 (“polyvinyl alcohol gel”). Right calf muscle T2 measurements were conducted in 9 healthy male volunteers using multiple-spin-echo magnetic resonance imaging. For phantoms and muscle (medial gastrocnemius), 5 regions of interests were selected. All region of interest values were expressed as the mean ± standard deviation. The T2 effective signal-ratio characteristics were used as an index to evaluate the magnetic resonance image quality for the calculation of T2 from T2- weighted images. The T2 accuracy was evaluated to determine the T2 reproducibility and the goodness-of-fit from the probability Q. Results: For the phantom and polyvinyl alcohol gel, the standard deviation of the magnetic resonance image signal at each echo time was narrow and monoexponential, which caused large variations in the muscle T2 decay curves. The T2 effective signal-ratio change varied with T2, with the greatest decreases apparent for a short T2. There were no significant differences in T2 reproducibility when > 3 measurement points were used. There were no significant differences in goodnessof- fit when > 6 measurement points were used. Although the measurement point evaluations were stable when > 3 measurement points were used, calculation of T2 using 4 measurement points had the highest accuracy according to the goodnessof- fit. Even if the number of measurement points was increased, there was little improvement in the probability Q. Conclusion: Four measurement points gave excellent reproducibility and goodnessof- fit when muscle T2 was considered mono-exponential.
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Combustion of stratified charge propane-air mixture with swirling flow in a constant-volume vessel
Eiji Tomita,Nobuyuki Kawahara,Atsushi Nishiyama,Sadami Yoshiyama,Yoshisuke Hamamoto 한국자동차공학회 2001 한국자동차공학회 Symposium Vol.- No.-
Direct injection spark ignition engines can achieve better thermal efficiency by applying stratified fuel concentration in the combustion chamber. The purpose of this study is to clarify the combustion in such inhomogeneous fuel concentration field. The combustion of inhomogeneous fuel concentration field in a cylindrical constant volume vessel was fundamentally investigated axisymmetrically. A swirling fuel-air mixture was produced in the vessel. A rich fuel concentration was formed near the center of the vessel by the injection of propane. The mixture was ignited at the center of the vessel. The experimental runs were done under various conditions at fuel distribution and swirl flow at the ignition timing. The fuel concentration distribution at the ignition timing was measured using laser-induced fluorescence. The gas flow field was obtained with a laser Doppler velocimeter in advance. The pressure history in the combustion chamber was analyzed to determine the combustion characteristics. Furthermore, a high-speed video camera was used to capture the flame development. The flame can propagate and the combustion occurs even in an ultra lean mixture of equivalence ratio of 0.3 in total. As the fuel concentration near the spark location approximates stoichiometric, flame propagation of the initial stage of the combustion becomes faster under an ultra lean mixture condition.<br/> <br/>
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Yano Yuichiro,Kanegae Hiroshi,Node Koichi,Mizuno Atsushi,Nishiyama Akira,Rakugi Hiromi,Itoh Hiroshi,Kitaoka Kaori,Kashihara Naoki,Ikeno Fumiaki,Tsuji Ichiro,Okada Kunio 한국역학회 2022 Epidemiology and Health Vol.44 No.-
OBJECTIVES: Using a dataset from a survey on national health and productivity management, we identified health and productivity factors associated with organizational profitability. METHODS: The Ministry of Economy, Trade and Industry conducted an annual survey on Health and Productivity Management between 2014 and 2021. We assessed the associations of organizational health and productivity management using survey questions collected in 2017 and 2018, and the rate of change in profits from 2017 and 2018 to 2020. We identified factors associated with organizational profitability using eXtreme Gradient Boosting, and calculated SHapley Additive exPlanation (SHAP) values for each factor. RESULTS: Among 1,593 companies (n= 4,359,834 employees), the mean age for employees at baseline was 40.3 years and the proportion of women was 25.8%. The confusion matrix for evaluating model performance had accuracy of 0.997, precision of 0.993, recall of 0.997; and area under the precision-recall curve of 0.999. The most important factors related to an increase in corporate profits were the percentage of current smokers (SHAP value 0.121), per-employee cost for health services (0.084) and medical services (0.050); the percentage of full-time employees working in sales departments (0.074), distribution or customer service departments (0.054); the percentage of employees who sleep well (0.055); and the percentage of employees who have a habit of regular exercise within a company (0.043). CONCLUSIONS: The lifestyle health risk factors of employees and organizations’ management systems were associated with organizational profitability. Lifestyle medicine professionals may demonstrate a significant return on investment by creating a healthier and more productive workforce.
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압전순,구보전륭이,서산영일랑,안등윤,립원순삼,급천신효,Oshida, Atsushi,Kubota, Ryuji,Nishiyama, Eiichiro,Ando, Jun,Kasahara, Junzo,Nishizawa, Azusa,Kaneda, Kentaro Korean Society of Earth and Exploration Geophysici 2008 지구물리와 물리탐사 Vol.11 No.1
지각구조 연구에서 해저면 지진계(OBS)의 위치정보는 OBS-에어건 탄성파 탐사에 있어서 매우 중요한 변수들중의 하나이다. 이 변수의 정확도을 향상시키기 위해 우리는 이용 가능한 음향 트랜스폰더에 의한 거리 정보와 함께 에어건 발파 자료와 수심 자료를 이용하여 OBS 위치를 결정하는 새로운 방법을 개발하였다. 음향 트랜스폰더로 얻은 거리 자료가 3 지점 미만의 것일 때에는 에어건 발파에 의해 발생하여 OBS에 기록된 수중 직접파의 주시가 OBS 위치 결정에 매우 중요한 정보로 활용된다. 그 새로운 방법은 두 단계로 이루어져 있다. 첫 번째 단계에서는 광역 검색이 이루어지는데 이는 수심 격자상에서 에어건 발파로부터 나온 수중 직접파의 관측 주시와 트랜스폰더 시스템을 사용하여 얻은 음향 거리로 설명할 수 있는 가장 가까운 노드를 찾는 것이다. 만약 OBS가 위치한 해저면 지형이 매우 험하다면 정밀한 2D 수심 데이터의 사용이 가장 중요하다. 국부적으로 수렴하는 최소값에 빠지지 않기 위해 첫 번째 단계에서 얻은 노드의 위치는 두 번째 단계의 초기값으로 사용된다. 두 번째 단계에서는 비선형 역산법이 수행된다. 만일 OBS의 내부 시계가 큰 편차를 보인다면 이 방법을 사용한 최종 OBS 위치와 함께 내부 시계에 대한 보정 또한 이루어져야 한다. 우리는 여기에서 OBS 위치 결정에 사용한 각 측정값의 영향과 오차에 대해서도 토론하고자 한다.
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