担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 日本機械学会  

DOI： 10.1299/transjsme.23-00246

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.engfailanal.2023.107623

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

To investigate the tensile properties and slip deformation behavior of pure titanium thin wires with a small ratio of the diameter to the grain size, tensile tests and a stepwise tensile test were performed using specimens with a diameter of approximately 170 μm and grain sizes of 17 and 87 μm, corresponding to diameter-to-grain-size ratios of 10 and ∼2, respectively. The specimen with a diameter-to-grain-size ratio of 10 fractured through the growth of voids. The fracture morphology was similar to that of the bulk specimens. On the other hand, for specimens with a diameter-to-grain-size ratio of 2, fracture occurs owing to the local deformation, in which primary slip systems are activated in each grain. The stepwise tensile test of the specimen with a diameter-to-grain-size ratio of 2 indicated that the slip deformation tended to occur from the large grains. Moreover, the activities of the slip systems of grains were evaluated using the Schmid factor (SF) and critical resolved shear stress (CRSS) of each slip system. It was noted that slip systems with the highest SF∙CRSS−1 were activated for 30 out of 33 grains.

DOI： 10.1016/j.msea.2022.144532

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記述言語：日本語  

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J-GLOBAL

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s00170-021-07510-8

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1115/1.4048063

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/app10144883

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.psep.2020.01.025

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 日本機械学会  

<p>Pure titanium thin wires have been used for medical fields. It is important to investigate the possibility of non-destructive inspection of pure titanium thin wires for the safety utilization of them. In order to investigate a fracture prediction method for a pure titanium thin wire, we performed tensile and fatigue tests and a finite element analysis to analyze the changes of direct current potential difference and diameter distribution of the pure titanium thin wire during tensile and fatigue tests. It was found that a direct current potential difference method may be available for evaluating the tensile and fatigue damages of the pure titanium thin wire. In the tensile and fatigue tests, the normalized direct current potential difference increased almost linearly with an increase in the nominal strain, and a sign of an increase of the normalized direct current potential difference was observed when the fatigue crack propagated. Therefore, the nondestructive inspection could be conducted by setting a tolerance value of the normalized direct current potential difference, or detecting a sign of an increase in the normalized direct current potential difference. In addition, a method of predicting the fracture location from the diameter distribution change of the pure titanium thin wire was studied. The method could be applied to tensile and fatigue fractures.</p>

DOI： 10.1299/transjsme.19-00351

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

© 2019 by the authors. Hydrogen, which is expected to be a popular type of next-generation energy, is drawing attention as a fuel option for the formation of a low-carbon society. Because hydrogen energy is different in nature from existing energy technologies, it is necessary to promote sufficient social recognition and acceptability of the technology for its widespread use. In this study, we focused on the effect of initiatives to improve awareness of hydrogen energy technology, thereby investigating the acceptability of hydrogen energy to those participating in either several hydrogen energy technology introduction events or professional seminars. According to the survey results, participants in the technology introduction events tended to have lower levels of hydrogen and hydrogen energy technology knowledge than did participants in the hydrogen-energy-related seminars, but confidence in the technology and acceptability of the installation of hydrogen stations near their own residences tended to be higher. It was suggested that knowledge about hydrogen and technology could lead to improved acceptability through improved levels of trust in the technology. On the other hand, social benefits, such as those for the environment, socioeconomics, and energy security, have little impact on individual levels of acceptance of new technology.

DOI： 10.3390/su11226339

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.1115/PVP2019-93546

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.1016/j.prostr.2018.12.087

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

© 2018 Hydrogen Energy Publications LLC Hydrogen, as a future energy carrier, is receiving a significant amount of attention in Japan. From the viewpoint of safety, risk evaluation is required in order to increase the number of hydrogen refueling stations (HRSs) implemented in Japan. Collecting data about accidents in the past will provide a hint to understand the trend in the possibility of accidents occurrence by identifying its operation time However, in new technology; accident rate estimation can have a high degree of uncertainty due to absence of major accident direct data in the late operational period. The uncertainty in the estimation is proportional to the data unavailability, which increases over long operation period due to decrease in number of stations. In this paper, a suitable time correlation model is adopted in the estimation to reflect lack (due to the limited operation period of HRS) or abundance of accident data, which is not well supported by conventional approaches. The model adopted in this paper shows that the uncertainty in the estimation increases when the operation time is long owing to the decreasing data.

DOI： 10.1016/j.ijhydene.2018.10.175

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

© 2018 by the authors. Hydrogen fueling stations are essential for operating fuel cell vehicles. If multiple safety measures in a hydrogen fueling station fail simultaneously, it could lead to severe consequences. To analyze the risk of such a situation, we developed a physical model of a hydrogen fueling station, which, when using, the temperature, pressure, and flow rate of hydrogen could be simulated under normal and abnormal operating states. The physical model was validated by comparing the analytical results with the experimental results of an actual hydrogen fueling station. By combining the physical model with a statistical method, we evaluated the significance of the safety measures in the event wherein multiple safety measures fail simultaneously. We determined the combinations of failures of safety measures that could lead to accidents, and suggested a measure for preventing and mitigating the accident scenario.

DOI： 10.3390/su10113846

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.microrel.2018.04.005

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

© 2018 Elsevier Ltd Fatigue tests and hardness tests were conducted in order to clarify the effects of the shapes of small flaws and damage caused by a focused ion beam (FIB) on the fatigue strength characteristics of annealed medium‑carbon steel. The notch root radius of the flaw at the branch point dominates the type of the fatigue limit and was found to be approximately 50 μm, a value that was significantly smaller than the 500 μm of two-dimensional notches in steel. The effect of the FIB-damaged layer on fatigue crack initiation from the FIB-milled notch in the steel was negligible. Moreover, the present study indicated that the effect of the FIB-damaged layer on the fatigue crack initiation at the FIB-milled notch could be evaluated simply by using a hardness test for the other materials and FIB conditions.

DOI： 10.1016/j.engfailanal.2018.02.005

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記述言語：日本語   出版者・発行元：日本空気清浄協会  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

© 2017 Elsevier Ltd In order to investigate the stress and strain distributions caused by the grain anisotropy of polycrystalline β-Sn, a finite-element (FE) analysis was conducted using a polycrystalline model that considers the effect of grain anisotropy on the elastic and plastic properties. Even in the case of thermal free expansion with a temperature change of 75 °C, plastic strains can be generated locally in polycrystalline β-Sn. This might be due to the high anisotropy of the thermal expansion coefficient and the low yield strength of β-Sn. It was found that both in-phase and out-of-phase thermal stresses can be present in the polycrystalline β-Sn simultaneously. The highest stress and strain appeared in the grains whose orientation is relatively different from those of neighboring grains, near the grain boundaries. This might cause the formation of a grain boundary void in the Pb-free solder. Comparing the strain distribution due to the thermal expansion coefficient anisotropy and the Young&#039;s modulus anisotropy, it was determined that the maximum value of the plastic strain due to the thermal expansion coefficient anisotropy is approximately 10% higher than that due to the anisotropy of Young&#039;s modulus, and the high strain areas are also different in the two cases. The thermo-mechanical fatigue life of β-Sn might be shorter than that estimated using the isothermal low cycle fatigue life at the same level as the macroscopic strain and could not be estimated by the previous method.

DOI： 10.1016/j.microrel.2017.02.009

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Adequate safety measures are crucial for preventing major accidents at hydrogen fueling stations. In particular, risk analysis of the domino effect at hydrogen fueling stations is essential because knock-on accidents are likely to intensify the consequences of a relatively small incident. Several risk assessment studies have focused on hydrogen fueling stations, but none have investigated accidental scenarios related to the domino effect at such stations. Therefore, the purpose of this study is to identify a domino effect scenario, analyze the scenario by using simulations and propose safety measures for preventing and mitigating of the scenario. In this hazard identification study, we identified the domino effect scenario of a hydrogen fueling station with an on-site hydrogen production system involving methylcyclohexane and investigated through simulations of the scenario. The simulations revealed that a pool fire of methylcyclohexane or toluene can damage the process equipment and that thermal radiation may cause the pressurized hydrogen tanks to rupture. The rupture-type vent system can serve as a critical safety measure for preventing and mitigating the examined scenario. (C) 2016 The Authors. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

DOI： 10.1016/j.ijhydene.2016.11.072

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記述言語：日本語   出版者・発行元：水素エネルギー協会  

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.ijhydene.2016.08.060

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.ijhydene.2016.03.143

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.ijhydene.2015.11.039

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

Hydrogen fueling stations are critical infrastructure for facilitating the commercialization of fuel cell vehicles (FCVs). In Japan, few hydrogen fueling stations have been built but several are under design or construction stages. It will be difficult to construct stand-alone hydrogen fueling stations in many locations in Japan because of the narrow spaces in urban cities. Therefore, hybrid stations with gasoline and hydrogen supply systems will be constructed to effectively use small spaces. Safety measures must be incorporated into the stations. Although stand-alone hydrogen fueling stations using compressed and liquid hydrogen have been investigated with risk assessment, the hybrid gasoline-hydrogen fueling stations have not been analyzed yet. This paper presents risk assessment from a Hazard Identification Study (HAZID) for identification of inherent accident scenarios and risks relating to gasoline and hydrogen supply systems. The study shows that HAZID was an effective assessment tool because it indicated similar accident scenarios analyzed by HAZOP and FMEA. Furthermore, HAZID revealed inherent scenarios and risks.

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.engfracmech.2014.11.005

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その他リンク： http://orcid.org/0000-0002-2108-2258

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s12206-014-0816-9

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その他リンク： http://orcid.org/0000-0002-2108-2258

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.engfracmech.2013.11.016

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その他リンク： http://orcid.org/0000-0002-2108-2258

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1520/JTE20120176

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その他リンク： http://orcid.org/0000-0002-2108-2258

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.4028/www.scientific.net/KEM.488-489.319

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その他リンク： http://orcid.org/0000-0002-2108-2258

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.scriptamat.2010.12.032

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その他リンク： http://orcid.org/0000-0002-2108-2258

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.scriptamat.2010.09.033

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その他リンク： http://orcid.org/0000-0002-2108-2258

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1299/kikaia.76.1002

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1299/kikaia.76.251

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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その他リンク： http://orcid.org/0000-0002-4982-257X

開催年月日： 2023年

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開催年月日： 2022年

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開催年月日： 2021年5月28日 - 2021年5月30日

記述言語：日本語   会議種別：口頭発表（一般）  

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開催年月日： 2021年5月28日 - 2021年5月30日

記述言語：日本語   会議種別：口頭発表（一般）  

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開催年月日： 2021年

記述言語：日本語  

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開催年月日： 2021年

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開催年月日： 2021年

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開催年月日： 2021年

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開催年月日： 2020年11月14日 - 2020年11月15日

記述言語：日本語   会議種別：口頭発表（一般）  

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開催年月日： 2020年9月13日 - 2020年9月16日

記述言語：日本語   会議種別：口頭発表（一般）  

<p>To investigate effects of dislocation density on microscopic stress distribution and macroscopic stress-strain relation, we conducted crystal plastic homogenization finite element analysis of Ti-6242 alloy subjected to in-plane reverse loading with dislocation density calculation. As a result, Statistically Stored (SS) dislocation density increased with occurrence of slip deformation for all conditions. On the other hand, Geometrically Necessary (GN) dislocation density was less likely to accumulate at the interface in the parallel relationship between primary slip systems of hcp and bcc. Although GN dislocations only develop near the interface, a large increase in GN dislocation density affects the macroscopic stress-strain relation.</p>

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開催年月日： 2020年5月

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開催年月日： 2020年3月

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開催年月日： 2019年11月2日 - 2019年11月4日

記述言語：日本語   会議種別：口頭発表（一般）  

<p>Various mechanical components are subjected to random multiaxial vibration. For their safe and effective operation, it is essential to precisely evaluate the fatigue strength of the materials under multiaxial random vibration. However, the mechanisms and evaluation methods remain unclear. In this study, we performed the multiaxial random vibration experiments using aluminum alloy A5056 specimens in order to discuss a method for evaluating the vibration fatigue strength of materials. The multiaxial random vibration experiments were conducted at an acceleration input of 70 G_rms within a frequency band of 10–5000 Hz under a nitrogen gas environment at a room temperature. During the multiaxial random vibration experiments the strains of the specimen were measured using 3-axis and 1-axis strain gauges and the maximum principal strains and their directions of a fracture part were estimated. Based on the results, the method for evaluating the vibration fatigue strength of materials was discussed.</p>

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開催年月日： 2019年10月

記述言語：日本語  

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開催年月日： 2019年9月8日 - 2019年9月11日

記述言語：日本語   会議種別：口頭発表（一般）  

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開催年月日： 2019年9月8日 - 2019年9月11日

記述言語：日本語   会議種別：口頭発表（一般）  

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開催年月日： 2019年9月8日 - 2019年9月11日

記述言語：日本語   会議種別：口頭発表（一般）  

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開催年月日： 2018年

記述言語：英語  

© GCPS 2018.All right reserved. New perspectives on a comprehensive societal risk framework for technological systems are introduced and discussed in relation to an example application involving a hydrogen fueling station for fuel cell vehicles. The comprehensive societal risk framework consists of not only technological and economic risks, but also environmental and societal risks. This framework will be indispensable to risk communication efforts and initiatives to foster the public acceptance of technological systems.

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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In this study, we propose a method for assessing the applicability of an artificial defect as a small initial crack for fatigue limit evaluation. The proposed method is applied to drill holes and sharp notches introduced using a focused ion beam (FIB) technique in annealed 0.45% carbon steel. It is found that under rotating bending fatigue, an FIB notch can be used as a small initial crack for fatigue limit evaluation, whereas a drill hole cannot, for of ∼50 μm. Here, is the square root of the area obtained by projecting the defect onto a plane perpendicular to the load axial direction. The results indicate that an FIB notch can be used as a small initial crack for fatigue limit evaluation in a greater number of materials than those in which a drill hole can be used.

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その他リンク： http://orcid.org/0000-0002-2108-2258

記述言語：日本語  

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In order to investigate the effect of gaseous hydrogen on cyclic slip behavior around an early stage (stage Ifatigue crack tip, fatigue crack growth (FCGtests using a single-crystalline Fe-3.2wt.%Si alloy are conducted respectively in a hydrogen atmosphere and in a helium atmosphere. The cross-sectional observations of the crack tips by both electron backscatter diffraction (EBSDmethod and transmission electron microscopy (TEMsuccessfully reveal the following points. In helium atmosphere, FCG is preceded by formation of cell structures and crack propagates along cell boundaries. In hydrogen atmosphere, on the other hand, no cells are seen, and crack growth process is similar to that observed in a stage II type FCG. Crack extension resistance in hydrogen is postulated to be lower than that in helium, indicating that the mode of FCG in hydrogen is more critical than that in helium.

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その他リンク： http://orcid.org/0000-0002-2108-2258

記述言語：日本語  

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