Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Jeong, S. G.*; Kwon, J.*; Kim, E. S.*; Prasad, K.*; Harjo, S.; Gong, W.; 川崎 卓郎; Estrin, Y.*; Bouaziz, O.*; Hong, S. I.*; et al.
Materials Science & Engineering A, 942, p.148712_1 - 148712_11, 2025/10
The cellular structure plays a key role in determining the mechanical properties of metal additive manufacturing (MAM) components. This study presents in situ neutron diffraction and dislocation density-based modeling for a CoCrFeMnNi high-entropy alloy (HEA) made via directed energy deposition (DED). A constitutive model based on the Kocks-Mecking-Estrin framework was used to represent the cellular structure. Parametric analysis showed lower dislocation accumulation and annihilation rates in the as-built sample (with cellular structure) than in the heat-treated one. These differences are linked to dislocation forest networks and local stacking fault energy variations. Dislocation density across cell interiors and walls was also compared with deformation-induced dislocation cells.
ders band-assisted high uniform ductility in ultrastrong ferrous medium-entropy alloy via hierarchical microstructureKwon, H.*; Lee, J. H.*; Zargaran, A.*; Harjo, S.; Gong, W.; Wang, J.*; Gu, G. H.*; Lee, B.-J.*; Bae, J. W.*; Kim, H. S.*
International Journal of Plasticity, 190, p.104378_1 - 104378_18, 2025/07
被引用回数：0 パーセンタイル：0.00(Engineering, Mechanical)In this work, we harness a hierarchical microstructure to simultaneously tailor strengthening and deformation mechanisms in a Co
Cr
Fe
Ni
Mo
(at%) ferrous medium-entropy alloy (MEA). A simple thermomechanical process (cold rolling and 90 s annealing) produces ultrafine recrystallized grains, non-recrystallized grains with substructures, and intragranular nanoprecipitates. This structure, with high dislocation density and fine grains, yields a high strength of 
1.60 GPa but can risk premature fracture. To overcome this, Lders deformation, enabled by ultrafine grain boundaries and stress-induced martensitic transformation at pre-existing nucleation sites, is employed. Stable Lders band propagation delays strain hardening and enables large uniform ductility. As a result, a tensile strength of 1.84 GPa and uniform elongation of 20% are achieved, matching the best tensile properties among reported multi-principal element alloys.
Gu, G. H.*; Jeong, S. G.*; Heo, Y.-U.*; Harjo, S.; Gong, W.; Cho, J.*; Kim, H. S.*; 他4名*
Journal of Materials Science & Technology, 223, p.308 - 324, 2025/07
被引用回数：1 パーセンタイル：63.96(Materials Science, Multidisciplinary)Face-centered cubic (FCC) equi-atomic multi-principal element alloys (MPEAs) exhibit excellent mechanical properties from cryogenic to room temperatures. At room temperature, deformation is dominated by dislocation slip, while at cryogenic temperatures (CTs), reduced stacking fault energy enhances strain hardening with twinning. This study uses in-situ neutron diffraction to analyze the temperature-dependent deformation behavior of Al
(CoNiV)
, a dual-phase (FCC/BCC) medium-entropy alloy (MEA). At liquid nitrogen temperature (LNT), deformation twinning in the FCC matrix leads to additional strain hardening through the dynamic Hall-Petch effect, giving the appearance of improved strengthening at LNT. In contrast, BCC precipitates show dislocation slip at both 77 K and 298 K, with temperature-dependent lattice friction stress playing a significant role in strengthening. The study enhances understanding of deformation behaviors and provides insights for future alloy design.
浪江 将成; 斉藤 淳一; 岡 涼太郎*; Kim, J.-H.*
Vacuum, 234, p.114038_1 - 114038_9, 2025/04
被引用回数：0 パーセンタイル：0.00(Materials Science, Multidisciplinary)Wettability of titanium (Ti) and surface-modified (Oxidized or Fluorinated) Ti with liquid sodium (Na) were investigated via experiments and theoretical calculations. From the experimental results, a sliding angle of Na droplet on oxidized Ti was smaller than that on untreated Ti, indicating the worsening of wettability by oxidation. In contrast, the sliding angle of Na droplet on fluoridated Ti was larger than that on untreated Ti, indicating an improvement in wettability by fluorination. Additionally, the cluster models for the interface between Na droplets and treated or untreated Ti were constructed for theoretical calculations of electronic states at the interface, covalent and ionic bonds at the interface were evaluated from the calculation results. The sliding angles obtained in the wettability tests and the strength of covalent bonding at the interface showed no correlation, but good correlation was observed between the sliding angles and ionic bonding at the interface. Thus, the wettability of surface-modified Ti with liquid Na can be theoretically understood based on the atomic interactions at the interface.
Chung, J.-H.*; Kwangwoo, S.*; Yokoo, Tetsuya R.; 植田 大地*; 今井 正樹; Kim, H.-S.; Kiem, D. H.; Han, M. J.*; 社本 真一
Scientific Reports (Internet), 15, p.5978_1 - 5978_10, 2025/02
被引用回数：0 パーセンタイル：66.92(Multidisciplinary Sciences)Two dimensional honeycomb ferromagnets host massless Dirac magnons which are a bosonic analogue of Dirac fermions in graphene. The Dirac magnons may become massive and topological when the time-reversal symmetry breaks and an energy gap opens up at the Dirac point, which was experimentally observed in Cr
-based van der Waals magnets. Here, we investigate the spin wave excitations in the 
magnetic oxide FeTiO with Fe
electrons (
). Using inelastic neutron scattering, we observe two magnon bands separated by a 1.2-meV gap at the Dirac points indicating that its Dirac magnons are massive. Using the linear spin-wave and density functional theory calculations, we find that the spin-orbit-coupled antisymmetric Dzyaloshinskii-Moriya exchanges can best account for the observed Dirac gap opening. The associated Berry curvature and Chern number (
) indicate that FeTiO hosts topological spin excitations via time-reversal symmetry breaking of Dirac magnons.
Cho, S. H.*; Cho, S. W.*; Lv, Z.*; 関根 由莉奈; Liu, S.*; Zhou, M.*; Nuxoll, R. F.*; Kanatzidis, E. E.*; Ghaffari, R.*; Kim, D.*; et al.
Lab on a Chip, 9 Pages, 2025/00
被引用回数：1 パーセンタイル：89.22(Biochemical Research Methods)アミノ酸は体内のタンパク質合成と代謝プロセスに不可欠な物質である。本研究では、運動中の汗からのアミノ酸損失について定量的に調べることを目的とした。汗中のアミノ酸含有量をリアルタイムで分析するため、測定のための技術基盤としてウェアラブルなマイクロ流体システムを構築した。定量分析を実現するため、ウェアラブルデバイスに蛍光アッセイを組み込み、さらにスマートフォンベースの画像化技術を統合させたシステムを開発した。
浪江 将成; 斉藤 淳一; 池田 明日香; 岡 涼太郎*; Kim, J.-H.*
Surfaces (Internet), 7(3), p.550 - 559, 2024/09
The iron (Fe) specimens selected as the substrate metal for this study were surface-treated using fluorine gas, and their wettability with liquid sodium (Na) was evaluated using the sliding angle. Additionally, the surface morphology and binding state were analyzed, and the applicability of wettability control with liquid sodium by fluorination was discussed using the analysis results. Fluorination formed a fluoride layer comprising FeF
and FeF
bonds on the iron surface. The composition of the fluoride layer varied, depending on the treatment conditions. The surface of the specimen that contains a lot of FeF bonds had a small sliding angle for the liquid sodium droplet and was harder to wet than the untreated specimen. In contrast, the surface of the specimen that contains a lot of FeF bonds had a large sliding angle for the liquid sodium droplet and was easier to wet than the untreated specimen. These results indicate that fluorination is an effective surface modification technique that can be applied to control the wettability of iron with liquid sodium.
Khemchandani, K. P.*; Mart
nez Torres, A.*; Kim, S.-H.*; Nam, S.-I.*; 保坂 淳; 永廣 秀子*
EPJ Web of Conferences, 301, p.03001_1 - 03001_10, 2024/08
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)3個の軽いクォークからなるバリオン共鳴がバレンスクォーク模型で記述できない例について議論する。
久保田 真彦*; Kim, S.-Y.*; Wu, H.*; 渡部 創; 佐野 雄一; 竹内 正行; 新井 剛*
Journal of Radioanalytical and Nuclear Chemistry, 333(5), p.2413 - 2420, 2024/05
To minimize the use of organic solvents and achieve a selective adsorption separation of minor actinides (MA(III)) and Ln(III), adsorbents consisting of SiO-P particles impregnated with hexaoctylnitrilotriacetamide (HONTA) were prepared. Batch experiments were performed to evaluate the adsorption properties of the HONTA/SiO-P adsorbent for MA(III) and simulated fission products in HNOsolution. The uniform distribution of Eu(III) on the adsorbent was confirmed via particle induced X-ray emission analysis, and X-ray photoelectron spectroscopy revealed that EuNO was the adsorbed species. This study provides a simplified process for the separation of MA(III) using a HONTA/SiO-P packed column.
Kim, Y. S.*; Chae, H.*; Lee, D.-Y.*; Han, J. H.*; Hong, S.-K.*; Na, Y. S.*; Harjo, S.; 川崎 卓郎; Woo, W.*; Lee, S.-Y.*
Materials Science & Engineering A, 899, p.146453_1 - 146453_7, 2024/05
被引用回数：7 パーセンタイル：83.40(Nanoscience & Nanotechnology)This work focused on the mechanical properties and serration-involved deformation behavior of advanced alloys at 15 K. Evolution of stacking faults and 
-martensite improved the mechanical performance of CoCrNi alloys, and significant strain-induced martensite transformation of DED-SS316L led to superior strength and strain hardening. A magnitude in stress drop was governed by dislocation density, phase type, and lattice defects, irrespective of processing method. FCC {200} notably was influenced recovery behavior after stress drop, and the contribution of strain energy density by serration on tensile toughness was the greatest for HR-CoCrNi.
大沢 直樹*; Kim, S.-Y.*; 久保田 真彦*; Wu, H.*; 渡部 創; 伊藤 辰也; 永石 隆二
Nuclear Engineering and Technology, 56(3), p.812 - 818, 2024/03
被引用回数：2 パーセンタイル：59.21(Nuclear Science & Technology)An impregnated silica-based adsorbent was prepared by combining HONTA extractant, Crea extractant, and macroporous silica polymer composite particles (SiO-P). The performance of platinum-group metals adsorption and separation on prepared (HONTA + Crea)/SiO-P adsorbent was assessed by batch-adsorption and chromatographic separation studies. (HONTA + Crea)/SiO-P adsorbent showed high adsorption performance of Pd(II) owing to an affinity between Pd(II) and Crea extractant based on the Hard and Soft Acids and Bases theory. The chromatographic experiment showed that Pd(II) was recovered entirely from the feed solution using 0.2 M thiourea in 0.1 M HNO. Possibility of recovery of Zr(IV), Mo(VI), and Re(VII) was also observed using the (HONTA + Crea)/SiO-P adsorbent.
Kim, G.*; Cho, S.-M.*; Im, S.*; Suh, H.*; 諸岡 聡; 菖蒲 敬久; 兼松 学*; 町田 晃彦*; Bae, S.*
Construction and Building Materials, 411, p.134529_1 - 134529_18, 2024/01
被引用回数：12 パーセンタイル：72.15(Construction & Building Technology)This study explores the influence of the interatomic structure of sodium aluminosilicate hydrate (N-A-S-H) with varying silica contents on the mechanical properties of metakaolin-based geopolymer. Geopolymer pastes comprising Si/Al ratios between 2.0 and 3.0 were synthesized. A larger number of Si-O-Si linkages compared to Si-O-Al linkages and a higher atomic number density were found in the geopolymers with higher silica contents, which enhanced the compressive strength of the geopolymer pastes up to the optimal Si/Al ratio of 2.5. The paste with a Si/Al = 2.5 exhibited a greater portion of Q
(1Al and 2Al) and denser morphology compared to the other geopolymer pastes. Furthermore, in-situ high-energy synchrotron X-ray scattering experiments were conducted to assess the elastic modulus of the aluminosilicate structure at a local atomic scale. The modulus value in real space decreases with increasing silica contents up to Si/Al = 2.5 and increases with the presence of excessive unreacted silica fume. The modulus value in reciprocal space for the axial and lateral directions both presented a positive value at the geopolymer comprising a Si/Al ratio higher than 2.5, indicating that the load-bearing property of N-A-S-H changed at higher Si/Al ratios. Moreover, the smallest difference between the strains along the axial and lateral directions was detected for the geopolymer with Si/Al = 2.5 in both the real and reciprocal space, owing to the most interconnected and flexible nanostructure, which led to the highest mechanical strength.
池田 一貴*; 佐次田 頌*; 大友 季哉*; 大下 英敏*; 本田 孝志*; 羽合 孝文*; 齋藤 開*; 伊藤 晋一*; 横尾 哲也*; 榊 浩司*; et al.
International Journal of Hydrogen Energy, 51(Part A), p.79 - 87, 2024/01
被引用回数：6 パーセンタイル：37.32(Chemistry, Physical)Low-vanadium-concentration alloys have low durability, and their hydrogen absorption and desorption amounts decrease by 20% after 100 cycles. In this study, we conducted reverse Monte Carlo modeling on X-ray diffraction patterns and neutron pair distribution functions of the hydrogen-absorbed and desorbed samples of a V
Ti
Cr
alloy to analyze the variations in the local structure. The local structure surrounding the hydrogen atom in the hydrogen-absorbed phase exhibited minimal changes. In contrast, hydrogen occupied both tetrahedral and octahedral sites of the hydrogen-desorbed phase almost equally during the early cycles; however, the amount of hydrogen occupying the tetrahedral sites increased with the number of cycles.
Cho, S.*; Suh, H.*; Im, S.*; Kim, G.*; 兼松 学*; 諸岡 聡; 町田 晃彦*; 菖蒲 敬久; Bae, S.*
Construction and Building Materials, 409, p.133866_1 - 133866_20, 2023/12
被引用回数：14 パーセンタイル：80.08(Construction & Building Technology)The effects of various initial carbonation curing environments on the phase evolution and resulting mechanical characteristics of tricalcium silicate paste were studied. For the analyses of the reaction products and microstructure, synchrotron X-ray diffraction, thermogravimetry, Fourier transform-infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy and high-resolution X-ray computed tomography were utilized. CS cured under carbonation environment pressurized by 0.1 MPa showed excellent mechanical properties owing to the highest degree of reaction and homogeneous generation of CaCO with low-Ca/Si calcium silicate hydrates, resulting in a dense matrix with refined pore structure. CS paste treated under other carbonation conditions underwent deteriorative microstructural phase transitions, including void evolution by decalcification of C-S-H and an inhomogeneous composition of crystalline phases, resulting in inferior properties.
Yang, D. S.*; Wu, Y.*; Kanatzidis, E. E.*; Avila, R.*; Zhou, M.*; Bai, Y.*; Chen, S.*; 関根 由莉奈; Kim, J.*; Deng, Y.*; et al.
Materials Horizons, 10(11), p.4992 - 5003, 2023/09
被引用回数：21 パーセンタイル：85.84(Chemistry, Multidisciplinary)本論文では、ハード及びソフトハイブリッド材料システムでの3Dプリントによって形成されたマイクロ流体ネットワーク、統合バルブ、およびマイクロスケール光学キュベットにより、汗成分に対してその場で分光および蛍光分析した成果を紹介する。一連の試験により、これらのマイクロキュベットシステムが汗中の銅、塩化物、グルコースの濃度と汗のpHを実験室レベルの精度と感度で評価できることが実証された。
Mun, M.-H.*; Shin, I. J.*; Paeng, W.-G.*; 原田 正康*; Kim, Y.*
European Physical Journal A, 59(7), p.149_1 - 149_6, 2023/07
被引用回数：4 パーセンタイル：59.83(Physics, Nuclear)Using an extended parity doublet model with the hidden local symmetry, we study some properties of nuclei in the mean field approximation to see if the parity doublet model could reproduce nuclear properties and also to estimate the value of the chiral invariant nucleon mass 
preferred by nuclear structure. We first determine our model parameters using the inputs from free space and from nuclear matter properties. Then, we study some basic nuclear properties such as the nuclear binding energy with several different choices of the chiral invariant mass. We observe that our results approach the experimental values as is increased until = 700 MeV and start to deviate more from the experiments afterwards with m0 larger than = 700 MeV. From this observation, we conclude that = 700 MeV is preferred by nuclear properties. We then calculate some properties of several selected nuclei with = 700 MeV and compare them with experiments. Finally, we study the neutron-proton mass difference in some nuclei.
Kwon, H.*; Sathiyamoorthi, P.*; Gangaraju, M. K.*; Zargaran, A.*; Wang, J.*; Heo, Y.-U.*; Harjo, S.; Gong, W.; Lee, B.-J.*; Kim, H. S.*
Acta Materialia, 248, p.118810_1 - 118810_12, 2023/04
被引用回数：60 パーセンタイル：99.31(Materials Science, Multidisciplinary)Maraging steels, known for ultrahigh strength and good fracture toughness, derive their superior properties from lath martensite structure with high-density nanoprecipitates. In this work, we designed a novel Fe-based medium-entropy alloy with a chemical composition of Fe
Co
Ni
Mo
in atomic% by utilizing the characteristics of the maraging steels. By a single-step aging of only 10 min at 650 
C, the alloy showed microstructures consisting of a very high number density of (Fe, Co, Ni)
Mo
-type nanoprecipitates in lath martensite structure and reverted FCC phase, which led to ultrahigh yield strength higher than 2 GPa. This work demonstrates a novel direction to produce strong and ductile materials by expanding the horizons of material design with the aid of high-entropy concept and overcoming the limits of conventional materials.
synchrotron X-ray scattering and nanoindentation testIm, S.*; Jee, H.*; Suh, H.*; 兼松 学*; 諸岡 聡; Choe, H.*; 西尾 悠平*; 町田 晃彦*; Kim, J.*; Lim, S.*; et al.
Construction and Building Materials, 365, p.130034_1 - 130034_18, 2023/02
被引用回数：21 パーセンタイル：79.15(Construction & Building Technology)Nanocrystalline calcium-silicate-hydrate (C-S-H) is a typical heterogeneous material with a multiscale structure spanning a wide length scale from angstrom to micrometer, and whose structure is determined by the Ca/Si ratio. In this study, we directly applied compressive loads on synthetic C-S-H pastes with Ca/Si ratios of 0.6-1.2 and investigated their mechanical properties using the elastic modulus calculated at three length scale levels (i.e., angstrom to nanometer, micrometer, and millimeter) via in-situ synchrotron X-ray scattering, nanoindentation tests, and strain gauges, respectively. Further, 
Si nuclear magnetic resonance spectroscopy was conducted on the C-S-H pastes to elucidate the alterations in the silicate polymerization. The experimental results confirmed the deformation behavior of the C-S-H paste with different Ca/Si ratios under external loading, which was demonstrated to be transferred from the surface of the pastes to particles owing to the presence of multiscale pores.
阿久澤 禎*; Kim, S.-Y.*; 久保田 真彦*; Wu, H.*; 渡部 創; 佐野 雄一; 竹内 正行; 新井 剛*
Journal of Radioanalytical and Nuclear Chemistry, 331(12), p.5851 - 5858, 2022/12
被引用回数：5 パーセンタイル：55.11(Chemistry, Analytical)In this work, we have examined Ln(III) and MA(III) separation conditions by the extraction chromatography using HONTA adsorbent to decide the Ln(III)/MA(III) separation process fow. From the research results, we found the simulated element of Am(III) for HONTA adsorbent and the conditions to use it. In addition, Ln(III) and Am(III) (simulated element) separation experiments were carried out using the HONTA adsorbent packed column, we have determined the column separation conditions for Am(III) such as order of fow solution and fow rate.
and its impact on photoproduction of light hyperonsKhemchandani, K. P.*; Martnez Torres, A.*; Kim, S.-H.*; Nam, S.-I.*; 保坂 淳
Acta Physica Polonica A, 142(3), p.329 - 336, 2022/09
被引用回数：2 パーセンタイル：25.14(Physics, Multidisciplinary)In this work, we outline the findings of our recent study of the properties of and its consequential impacts on the cross-sections of the photoproduction of 
(1405). Further, we discuss the possibility of the existence of an isovector state with a mass similar to (1405), which we refer to as 
(1400). With the idea of motivating experimental investigations of (1400), we have studied its photo-production process and determined the respective cross-sections and polarization observables. We have studied also the coupling of to 
(1400) and found that it gives an important contribution to the cross-sections near the threshold. In the process, we have determined the branching ratios of the decay of to the final states involving (1405) and (1400) to be in the range of 6-7 MeV. Our findings can motivate the consideration of alternative processes in partial wave analyses of experimental data when studying the properties of .
