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Carbon Energy 2024年第7期6卷 83-93页

作者： Unsoo Kim Jeong-seok Nam Jungjin Yoon Jiye Han Mansoo choi Il Jeon Department of Mechanical Engineering Seoul National UniversitySeoulRepublic of Korea Global Frontier Center for Multiscale Energy Systems Seoul National UniversitySeoulRepublic of Korea Frontier Energy Solution SeoulRepublic of Korea Department of Nano Engineering Department of Nano Science and TechnologySKKU Advanced Institute of Nanotechnology(SAINT)Sungkyunkwan University(SKKU)SuwonRepublic of Korea Department of Materials Science and Engineering Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA

The successful utilization of an eco-friendly and biocompatible parylene-C substrate for high-performance solution-processed double-walled carbon nanotube(CNT)electrode-based perovskite solar cells(PSCs)was *** the use of a novel inversion transfer technique,vertical separation of the binders from the CNTs was induced,rendering a stronger p-doping effect and thereby a higher conductivity of the *** resulting foldable devices exhibited a power conversion efficiency of 18.11%,which is the highest reported among CNT transparent electrode-based PSCs to date,and withstood more than 10,000 folding cycles at a radius of 0.5 mm,demonstrating unprecedented mechanical ***,solar modules were fabricated using entirely laser scribing processes to assess the potential of the solution-processable nanocarbon ***,this is the only one to be processed entirely by the laser scribing process and to be biocompatible as well as eco-friendly among the previously reported nonindium tin oxide-based perovskite solar modules.

关键词： double-walled carbon nanotubes parylene substrates perovskite modules perovskite solar cells solution-processable electrodes surfactant removal

Fe-based high-entropy alloy with excellent mechanical properties enabled by nanosized precipitates and heterogeneous grain distribution

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Journal of Materials Science & Technology 2024年第14期181卷 71-81页

作者： Heechan Jung Sangwon Lee Taehyeok Kang Alireza Zargaran Pyuck-Pa choi seok Su Sohn Department of Materials Science and Engineering Korea UniversitySeoul 02841Republic of Korea Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea Graduate Institute of Ferrous and Energy Materials Technology Pohang University of Science and TechnologyPohang 37673Republic of Korea

High-entropy alloys(HEAs)consisting of CoCrFeNiAlTi systems,with a face-centered cubic(FCC)matrix reinforced by ordered L12 precipitates,have demonstrated exceptional strength-ductility ***,the current compositional design of HEAs heavily relies on high Ni and Co contents,compro-mising the balance between properties and ***,it is crucial to optimize the cost-performance trade-offby fine-tuning the range of Fe,Co,and Ni,while maintaining excellent strength-ductility *** this study,we propose a novel Fe-based HEA with nanosized precipitates and a heteroge-neous grain distribution,achieving a strength-ductility combination comparable to state-of-the-art Ni-or Co-based *** alloy benefits from both precipitation hardening and hetero-deformation-induced strengthening attributed to the heterogeneous grain distribution,resulting in excellent yield strength of 1433 MPa,tensile strength of 1599 MPa,and ductility of 22%.The microstructural evolution and its in-fluence on mechanical properties are unraveled with respect to the observation of precipitate-dislocation interaction and hetero-deformation-induced stress(HDI stress)*** study suggests that the challenge of balancing properties and cost can be addressed through optimized compositional and mi-crostructural design.

关键词： High-entropy alloys Precipitation Heterogeneous microstructure Mechanical property HDI stress

Finite element analysis using elasto-visco-plastic self-consistent polycrystal model for E-form Mg sheet subjected to bending

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Journal of Magnesium and Alloys 2023年第4期11卷 1393-1407页

作者： Bohye Jeon min-Seong Kim Shi-Hoon choi Youngung Jeong Department of Materials Convergence and System Engineering Changwon National UniversityChangwon-siGyeongnamRepublic of Korea Center for Energy Materials Research Korea Institute of Science and TechnologySeoulRepublic of Korea Department of Advanced Components and Materials Engineering Sunchon National UniversitySuncheon-siJeollanam-doRepublic of Korea School of Materials Science and Engineering Changwon National UniversityChangwon-siGyeongnamRepublic of Korea

The mechanical behavior of a magnesium alloy E-form under bending was investigated using the elasto-visco-plastic polycrystal model(ΔEVPSC) and its finite element(FE) implementation(ΔEVPSC-FE) developed in Jeong et al. and Jeong and Tomé. The crystallographic orientation distribution(COD) obtained from X-ray diffraction was used to represent the initial texture, and the Voce hardening parameters were calibrated by fitting the uniaxial tension and the compression flow stress curves. A quasi-static FE analysis of a miniaturized V-bending operation was conducted using the ΔEVPSC-FE model. The bending induced an inhomogeneous stress response along the through-thickness and the lateral directions, which was well captured by the model. Moreover, the predictive capability of the model was validated by comparing with various experimental results such as(1) force vs. displacement curves;(2) the through-thickness variations in the twin volume fraction;and(3) the changes in crystallographic texture as a function of displacement. Additional bending simulation was performed using an isotropic texture, the result of which suggests that the potential improvement in bendability of the magnesium alloy is attainable by weakening the initial texture. Moreover, the simulation results imply that the crystallographic texture, which may affect the twin activation across the thickness direction, plays a significant role in the shifting direction of the neutral layer.

关键词： FEM Texture V-bending Polycrystal Magnesium Elasto-visco-plasticity

Standardized ileal digestible lysine requirements based on growth performance and histochemical characteristics of male broilers from 10 to 21 d of age

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Animal Nutrition 2023年第1期12卷 145-150页

作者： Su Hyun An Boin Lee Young min choi Changsu Kong Department of Animal Science and Biotechnology Kyungpook National University37224SangjuRepublic of Korea Department of Animal Science Kyungpook National University37224SangjuRepublic of Korea

The growth performance and histochemical characteristics of breast muscle fibers were used to estimate the standardized ileal digestible(SID)Lys requirements for 10-to 21-d-old male *** hundred and sixty 10-d-old Ross 308 broilers(290±16.6 g)were allocated to 6 diets in a randomized complete block design with 6 replicate cages per treatment and 10 birds per *** 6 experimental diets were formulated to contain equally spaced increasing levels of SID Lys from 0.86%to 1.36%.The data were analyzed using the MIXED procedure of *** Lys requirements were estimated by the NLIN procedure of *** increase in dietary SID Lys from 0.86%to 1.36%resulted in a quadratic increase(P<0.05)in body weight gain(BWG),gain to feed ratio(G:F),breast weight,muscle cross-sectional area(MCSA),and fiber *** SID Lys requirements based on the one-slope broken-line,quadratic line,the first intercept between the plateau of the one-slope broken-line and quadratic-line models and 95%of the upper asymptote of the quadratic-line model were estimated to be 1.01%,1.19%,1.08%,and 1.13%for BWG,1.06%,1.22%,1.11%,and 1.16%for G:F,1.10%,1.29%,1.19%,and 1.22%for breast weight,1.06%,1.22%,1.12%,and 1.16%for MCSA,and 1.14%,1.22%,1.16%,and 1.16%for breast muscle fiber area,*** was concluded that the SID Lys requirements for broilers at the age of 10 to 21 d depended on the response variables used for estimation,and that histochemical characteristics of breast muscle fibers could be good indicators for estimating SID Lys requirements.

关键词： Requirement Lysine Growth performance Muscle fiber characteristics Broiler chicken

Potential risk factors for nonalcoholic steatohepatitis related to pancreatic secretions following pancreaticoduodenectomy

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World Journal of Gastroenterology 2011年第32期17卷 3716-3723页

作者： Sun Choon Song Seong Ho choi Dong Wook choi Jin seok Heo Woo seok Kim min Jung Kim Department of Surgery Samsung Medical Center Sungkyunkwan University School of Medicine

AIM: To identify risk factors for nonalcoholic steatohepatitis following pancreaticoduodenectomy, with a focus on factors related to pancreatic secretions. METHODS: The medical records of 228 patients who had a pancreaticoduodenectomy over a 16-mo period were reviewed retrospectively. The 193 patients who did not have fatty liver disease preoperatively were included in the final analysis. Hepatic steatosis was diagnosed using the differences between splenic and hepatic attenuation and liver-to-spleen attenuation as measured by non-enhanced computed tomography. RESULTS: Fifteen patients (7.8%) who showed postoperative hepatic fatty changes were assigned to Group A, and the remaining patients were assigned to Group B. Patient demographics, preoperative laboratory findings (including levels of C-peptide, glucagon, insulin and glucose tolerance test results), operation types, and final pathological findings did not differ significantly between the two groups; however, the frequency of pancreatic fistula (P = 0.020) and the method of pancreatic duct stenting (P = 0.005) showed significant differences between the groups. A multivari- ate analysis identified pancreatic fistula (HR = 3.332, P = 0.037) and external pancreatic duct stenting (HR = 4.530, P = 0.017) as independent risk factors for the development of postoperative steatohepatitis. CONCLUSION: Pancreatic fistula and external pancreatic duct stenting were identified as independent risk factors for the development of steatohepatitis following pancreaticoduodenectomy.

关键词： Nonalcoholic fatty liver diseases Nonalcoholic steatohepatitis Pancreatic duct stenting Pancreatic fistula Pancreatic surgery

Fully tunable Fabry-Pérot cavity based on MEMS Sagnac loop reflector with ultra-low static power consumption

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Microsystems & Nanoengineering 2024年第4期10卷 355-365页

作者： Young Jae Park Man Jae Her Youngjae Jeong Dong Ju choi Dong Uk Kim min Gi Lim Myung seok Hong Hyug Su Kwon Kyoungsik Yu Sangyoon Han Department of Robotics and Mechatronics Engineering Daegu Gyeongbuk Institute of Science and Technology(DGIST)Daegu 42988Republic of Korea School of Electrical Engineering Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Agency for Defense Development DaejeonRepublic of Korea

The Fabry-Pérot interferometer,a fundamental component in optoelectronic systems,offers interesting applications such as sensors,lasers,and *** this work,we show a tunable Fabry-Pérot cavity consisting of tunable Sagnac loop reflectors(SLRs)and phase shifters based on electrostatic microelectromechanical(MEMS)*** fabrication process of the device is compatible with the standard wafer-level silicon photonics fabrication *** electrostatic actuation mechanism provides well-balanced,scalable pathways for efficient tuning *** extinction ratio of the continuously tunable SLRs’reflectivity is larger than 20 *** 2πphase shifting is achieved,and response times of all the components are less than 25μ*** actuators have extremely low static power,measuring under 20 fW and the energy needed for tuning is both below 20 pJ.

关键词： tunable tuning interferometer

Strong contact coupling of neuronal growth cones with height-controlled vertical silicon nanocolumns

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Nano Research 2018年第5期11卷 2532-2543页

作者： Seong-min Kim Seyeong Lee Dongyoon Kim Dong-Hee Kang Kisuk Yang Seung-Woo Cho Jin seok Lee Insung S. choi Kyungtae Kang Myung-Han Yoon School of Materials Science and Engineering Gwangju Institute of Science and Technology Gwongju 61005 Republic of Korea Department of Biotechnology Yonsei University 50 Yonsei-ro Seodaemun-gu Seoul 03722 Republic of Korea Department of Chemistry Sookmyung Women's University Seoul 04310 Republic of Korea Center for Cell-Encapsulation Research Department of Chemistry KAIST Daejeon 34141 Republic of Korea Department of Applied Chemistry Kyung Hee University Yongin Gyeonggi 17104 Republic of Korea

In this study, we report that height-controlled vertically etched silicon nano- column arrays （vSNAs） induce strong growth cone-to-substrate coupling and accelerate in vitro neurite development while preserving the essential features of initial neurite formation. Large-scale preparation of vSNAs with flat head morphology enabled the generation of well-controlled topographical stimulation without cellular impalement. A systematic analysis on topography- induced variations on cellular morphology and cytoskeletal dynamics was conducted. In addition, neurite development on the grid-patterned vSNAs exhibited preferential adhesion to the nanostructured region and outgrowth directionality. The arrangement of cytoskeletal proteins and the expression of a focal adhesion complex indicated that a strong coupling existed between the underlying nanocolumns and growth cones. Furthermore, the height-controlled nanocolumn substrates differentially modulated neurite polarization and elongation. Our findings provide an important insight into neuron-nanotopography interactions and their role in cell adhesion and neurite development.

关键词： vertical silicon nanostructures metal-assisted chemical etching primary hippocampal neurons neurite outgrowth cytoskeletal dynamics

Polydopamine-derived N-doped carbon-wrapped Na3V2(PO4)3 cathode H with superior rate capability and cycling stability for sodium-ion I batteries

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Nano Research 2019年第2期12卷 397-404页

作者： Hyeongwoo Kim Hyojun Lim Hyung-seok Kim Ki Jae Kim Dongjin Byun Wonchang choi Center for Energy Storage Research Korea Institute of Science and Technology 5 Hwarang-ro 14-gil Seongbuk-gu Seoul 02792 Republic of Korea Department of Material Science and Engineering Korea University 145 Anam-ro Seongbuk-gu Seoul 02841 Republic of Korea Division of Energy & Environment Technology KIST School Korea University of Science and Technology 5 Hwarang-ro 14-gik Seongbuk-gu Seoul 02792 Republic of Korea Department of Energy Engineering Konkuk University 120 Neungdong-ro Gwangin-gu Seoul 05029 Republic of Korea

Na superionic conductor (NASICON)-type Na3V2(PO4)3 (NVP) has been regarded as a promising cathode material for sodium-ion batteries (SIBs). However, NVP suffers from poor cyclability and rate capability because of its intrinsically low electronic conductivity. Herein, we successfully syn thesized N-doped carb on-wrapped Na3V2(PO4)3 (NC@NVP) through the carb on izati on of polydopami ne, which is rich in nitrogen species. The strong adhesion properties of the polydopamine lead to effective and homogeneous wrapping of NVP particles, and it I is further turned into a con ductive N-doped carb on n etwork itself, providi ng facile diffusi on of electr ons and Na+ i ons duri ng battery operation. NC@NVP displays remarkable electrochemical performanee, even under harsh operating conditions, such as a high rate capability (discharge capacity of 70.88, 49.21 mA·h·g^-1 at 50 and 100 C), long-term cycling stability (capacity retention of 94.77% over 1,000 cycles at 20 C), and high-temperature cycling (capacity retention of 92.0% after 500 cycles at 60 ℃).

关键词： polydopamine N-doped carbon Na3V2(PO4)3 cathode sodium-ion batteries

Uncertainty analysis of flow rate measurement for multiphase flow using CFD

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Acta Mechanica Sinica 2015年第5期31卷 698-707页

作者： Joon-Hyung Kim Uk-Hee Jung Sung Kim Joon-Yong Yoon Young-seok choi Department of Mechanical Design Engineering Hanyang University Thermal & Fluid System R&BD Group Korea Institute of Industrial Technology Energy System Engineering University of Science and Technology

The venturi meter has an advantage in its use,because it can measure flow without being much affected by the type of the measured fluid or flow ***,it has excellent versatility and is being widely applied in many *** flow of a liquid containing air is a representative example of a multiphase flow and exhibits complex flow *** particular,the greater the gas volume fraction（GVF）,the more inhomogeneous the flow *** a result,using a venturi meter to measure the rate of a flow that has a high GVF generates an *** this study,the cause of the error occurred in measuring the flow rate for the multiphase flow when using the venturi meter for analysis by *** ensure the reliability of this study,the accuracy of the multiphase flow models for numerical analysis was verified through comparison between the calculated results of numerical analysis and the experimental *** a result,the Grace model,which is a multiphase flow model established by an experiment with water and air,was confirmed to have the highest ***,the characteristics of the internal flow Held about the multiphase flow analysis result generated by applying the Grace model were analyzed to find the cause of the uncertainty occurring when measuring the flow rate of the multiphase flow using the venturi meter.A phase separation phenomenon occurred due to a density difference of water and air inside the venturi,and flow inhomogeneity happened according to the flow velocity difference of each *** was confirmed that this flow inhomogeneity increased as the GVF increased due to the uncertainty of the flow measurement.

关键词： Multiphase flow Measurement Numerical analysis Venturi meter Gas volume fraction(GVF) Uncertainty Multiphase flow model Grace model

Congenital stapes suprastructure fixation presenting with fluctuating auditory symptoms:A case report

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World Journal of Clinical Cases 2023年第1期11卷 249-254页

作者： Sun choi seok Hyun Park Ji Su Kim Jiwon Chang Department of Otolaryngology-Head and Neck Surgery Kangnam Sacred Heart HospitalHallym University College of MedicineSeoul 07441South Korea

BACKGROUND Stapes ankylosis is a rare cause of conductive hearing loss,and stapes suprastructure fixation is extremely rare with fewer than 30 reported *** usually visit the clinic with non-progressive conductive hearing loss that typically began in the early years of *** SUMMARY Herein,we report a case of a 37-year-old female with an isolated stapedial suprastructure *** patient presented with unusual fluctuating auditory symptoms of tinnitus,ear fullness and mixed hearing ***-operative temporal bone computed tomography findings and operative findings revealed an isolated stapedial suprastructure fixation with monopod stapes caused by elongated pyramidal *** hearing threshold recovered completely,and fluctuating auditory symptoms disappeared after the *** This is the first report of stapedial suprastructure fixation with fluctuating auditory *** results are expected with surgical treatment.

关键词： Isolated stapes ankylosis Stapes suprastructure fixation Elongated pyramidal eminence Stapes monopod Fluctuating auditory symptoms Exploratory tympanotomy Case report