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Comparative study of extrudability, microstructure, and mechanical properties of AZ80 and BA53 alloys

Journal of Magnesium and Alloys 2023年第1期11卷 249-258页

作者： Sang-cheol Jin Jae Won Cha Jongbin Go Jun Ho Bae Sung Hyuk park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Department of Materials Science and Engineering Kyoto UniversityKyoto 606-8501Japan Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea

The extrudability,microstructural characteristics,and tensile properties of the Mg–5Bi–3Al(BA53)alloy are investigated herein by comparing them with those of a commercial Mg–8Al–0.5 Zn(AZ80)*** AZ80 is extruded at 400℃,severe hot cracking occurs at exit speeds of 4.5 m/min or *** contrast,BA53 is successfully extruded without any surface cracking at 400℃ and at high exit speeds of 21–40 m/*** extruded at 3 m/min(AZ80–3)and 40 m/min(BA53–40),both AZ80 and BA53 exhibited completely recrystallized microstructures with abasal ***,BA53–40 has a coarser grain structure owing to grain growth promoted by the high temperature in the deformation ***80–3 contains a continuous network of Mg_(17)Al_(12) particles along the grain boundaries,which form via static precipitation during natural air-cooling after the material exits the extrusion ***53–40 contains coarse Mg_(3)Bi_(2) particles aligned parallel to the extrusion direction along with numerous uniformly distributed fine Mg_(3)Bi_(2) ***80–3 has higher tensile strength than BA53–40 because the relatively finer grains and larger number of solute atoms in AZ80–3 result in stronger grain-boundary and solid-solution hardening effects,*** BA53 is extruded at a high temperature and extrusion speed of 400℃ and 40 m/min,respectively,the extruded material has a high tensile yield strength of 188 *** can be primarily attributed to the large particle hardening effect resulting from the numerous fine Mg_(3)Bi_(2) particles.

关键词： Mg-Bi-Al alloy Extrusion Hot cracking Second phase Tensile properties

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Size-dependent transition of the deformation behavior of Au nanowires

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Nano Research 2015年第3期8卷 941-947页

作者： Na-Young park Ho-Seok Nam PiI-Ryung Cha Seung-cheol Lee School of Advanced Materials Engineering Kookmin University Seou1136-702 R. O. Korea Future Convergence Research Division Korea Institute of Science and Technology (KIST) Seou1136-791 R. O. Korea Indo-Korea Science and Technology Center Korea Institute of Science and Technology (KIST) Seou1136-791 R. O. Korea

Inspired by the controversy over tensile deformation modes of single-crystalline 〈110〉/{111} Au nanowires, we investigated the dependency of the deformation mode on diameters of nanowires using the molecular dynamics technique. A new criterion for assessing the preferred deformation mode-slip or twin propagation--of nanowires as a function of nanowire diameter is presented. The results demonstrate the size-dependent transition, from superplastic deformation mediated by twin propagation to the rupture by localized slips in deformed region as the nanowire diameter decreases. Moreover, the criterion was successfully applied to explain the superplastic deformation of Cu nanowires.

关键词： Au nanowire molecular dynamics size-dependent transition tensile deformationmechanism

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Effects of Al addition on microstructure and mechanical properties of extruded Mg-3Bi alloy

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Journal of Magnesium and Alloys 2022年第7期10卷 1887-1898页

作者： Sang-cheol Jin Jae Won Cha Jun Ho Bae Hui Yu Sung Hyuk park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Implementation Research Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea School of Materials Science and Engineering Hebei University of TechnologyTianjin 300130China

Effects of Al addition to a Mg±Bi binary alloy on its microstructural characteristics and tensile properties after extrusion are investigated via extrusion of Mg-3Bi±x Al(x=0,1,and 2 wt%)billets and analysis of the extruded *** Al addition negligibly affects the second-phase particles of the extruded alloy;however,an increase in the Al content causes significant decreases in the average grain size and maximum texture intensity of the extruded material owing to an increase in the area fraction of dynamically recrystallized(DRXed)*** Al addition improves the strength of the extruded alloy;this improvement is attributed to the enhanced grain-boundary hardening and solid-solution hardening effects induced by grain refinement and Al solute atoms,*** the Al content increases from 0 wt%to 1 wt%and 2 wt%,the tensile elongation increases substantially from 2.8%to 9.4%and 16.9%,*** reduction in the number and size of un DRXed grains with increasing Al content suppresses the formation and coalescence of cracks in the un DRXed grains during tension,which results in a significant improvement in the tensile ductility of the extruded *** tensile deformation,large undesirable twins that act as crack initiation sites are locally formed in the un DRXed grains of the Mg-3Bi alloy,whereas relatively smaller twins are uniformly formed in both the DRXed and the un DRXed grains of the Mg-3Bi-2Al ***,the extruded Mg-3Bi-2Al alloy has a substantially higher tensile yield strength±elongation product(2924 MPa%)than the extruded Al-free B3 alloy(381 MPa%).

关键词： Mg-Bi-Al alloy Extrusion Microstructure Strength Ductility

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Multiplanar reformations and minimum intensity projections using multi-detector row CT for assessing anomalies and disorders of the pancreaticobiliary tree

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World Journal of Gastroenterology 2007年第31期13卷 4177-4184页

作者： Hyun cheol Kim Dal Mo Yang Wook Jin Chang Woo Ryu Jung Kyu Ryu Sung Il park Seong Jin park Hyeong cheol Shin Il Young Kim Department of Radiology East-West Neo Medical Center Kyung-Hee University Seoul Republic of Korea Department of Diagnostic Radiology Kwandong University Myongji Hospital Goyang Republic of Korea Department of Diagnostic Radiology Soonchunhyang University Bucheon Hospital Bucheon Republic of Korea Department of Diagnostic Radiology Soonchunhyang University Cheonan Hospital Cheonan Republic of Korea

CT scan is regarded as the imaging modality of choice in patients with pancreaticobiliary ductal abnormalities. However, the axial orientation of the CT images provides only limited anatomical view of pancreaticobiliary ductal abnormalities. The technological advances of multi-de-tector row CT and three-dimensional image processing in workstations allows rapid image acquisition and a short postprocessing time. In particular, multiplanar reforma-tions (MPR) and minimum intensity projections (MinIP) offer rapid and accurate images of the anatomy and ab-normalities of the pancreaticobiliary tree. Moreover, MPR and MinIP help determine the relationship between the pancreaticobiliary ductal anatomy and the surrounding structures. This pictorial review illustrates the wide spec-trum of images obtained by the MPR and MinIP of the anomalies and disorders of the pancreaticobiliary tree.

关键词： Multi-detector CT Bile Ducts Biliary System Pancreas Computer Applications-3D

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Fruits extracts of Hovenia dulcis *** lipopolysaccharide—stimulated inflammatory responses through nuclear factor—kappaB pathway in Raw 264.7 cells

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Asian Pacific Journal of Tropical Medicine 2016年第4期9卷 349-355页

作者： Ju-yeon park Jin-Young Moon Sun-Dong park Won-Hwan park Hyuck Kim Jai-Eun Kim Department of Acupoint College of Korean Medicine.Dongguk University Department of Prescription College of Korean MedicineDongguk University Department of Diagnostics College of Korean Medicine.Dongguk University Department of Pathology College of Korean Medicine.Dongguk University

Objective:To investigate the anti-inflammatory effects and the action mechanism of the fruits of Horenia dulcis(***) in lipopolysaccharide(LPS)-induced mouse macrophage Raw ***:The extract of *** fruits(EHDF) were extracted with 70%*** macrophages were treated with different concentrations of EHDF in the presence and absence of LPS(1 μg/mL).To demonstrate the inflammatory mediators including nitric oxide,inducible nitric oxide synthase and cyclooxygenase(COX)-2 expression levels were analyzed by usingin vitro assay ***-derived pro-inflammatory cytokines including interleukin-1 β.tumor necrosis factor- α and prostaglandin F_2 were determined using ELISA *** viability,heme oxygenase-1 expression,nuclear factor-kappaB and nuclear factor F.2-related factors 2 translocation were also ***:EHDF potently inhibited the LPS-stimulated nitric oxide,inducible nitric oxide ***-2,interleukin-1 β and tumor necrosis factor- α expression in a dose-dependent *** suppressed the phosphorylation of inhibited kappaB-alpha and p65 nuclear *** of macrophage cells with EHDF alone induced the heme oxygenase-1 and nuclear translocation of nuclear factor E2-reIated factor ***:These results suggest that the ethanol extract of *** fruit exerts its anti-inflammatory effects by inhibiting inhibited kappaBalpha phorylation and nuclear translocation of nuclear factor-kappaB.

关键词： Fruits of Hovenia dulcis Inflammation Macrophage Nuclear factor-kappaB Heme oxygenase-1

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Structural Characteristics of Allomyrina Dichotoma Beetle＇s Hind Wings for Flapping Wing Micro Air Vehicle

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Journal of Bionic Engineering 2014年第2期11卷 226-235页

作者： Ngoc San Ha Quang Tri Truong Hoang Vu Phan Nam Seo Goo Hoon cheol park Biomimetics and Intelligent Microsystem Laboratory Department of Advanced Technology Fusion Division of Interdisciplinary Studies Konkuk University Seoul 143-701 Republic of Korea

In this study, we present a complete structural analysis ofAllomyrina dichotoma beetle＇s hind wings by investigating their static and dynamic characteristics. The wing was subjected to the static loading to determine its overall flexural stiffness. Dy- namic characteristics such as natural frequency, mode shape, and damping ratio of vibration modes in the operating frequency range were determined using a Bruel ＆ Kjaer fast Fourier transform analyzer along with a laser sensor. The static and dynamic characteristics of natural Allomyrina dichotoma beetle＇s hind wings were compared to those of a fabricated artificial wing. The results indicate that natural frequencies of the natural wing were significantly correlated to the wing surface area density that was defined as the wing mass divided by the hind wing surface area. Moreover, the bending behaviors of the natural wing and artificial wing were similar to that of a cantilever beam. Furthermore, the flexural stiffness of the artificial wing was a little higher than that of the natural one whereas the natural frequency of the natural wing was close to that of the artificial wing. These results provide important information for the biomimetic design of insect-scale artificial wings, with which highly ma- neuverable and efficient micro air vehicles can be designed.

关键词： beetle hind wing flexural stiffness natural frequency mode shape Micro Air Vehicles (MAVs)

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Performance evaluations on inner vs. outer decomposition first parallel join algorithms for two nested loop joins

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Journal of Central South University 2014年第10期21卷 3873-3882页

作者： Seo-Young NOH Heejun YOON Il-yeon YEO Yoon-su JEONG Hyungwoo park National Institute of Supercomputing and Networking Korea Institute of Science and Technology Information Department of Information Communication Engineering Mokwon University

Two popular traditional join algorithms and their parallel versions are introduced. When designing join algorithms in serial computing environment, decomposing inner relation is considered as the right direction to save disk I/Os. However, two different decomposition algorithms are compared, such as inner vs. outer decomposition first algorithms for tuple-based and block-based nested loop joins, showing that the proposed approach is 20% better than general approach. Also lemmas are proved, when we have to use the outer decomposition first parallel join algorithms.

关键词： parallel join performance inner decomposition outer decomposition

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Accurate and scalable graph neural network force field and molecular dynamics with direct force architecture

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npj Computational Materials 2021年第1期7卷 650-658页

作者： cheol Woo park Mordechai Kornbluth Jonathan Vandermause Chris Wolverton Boris Kozinsky Jonathan P.Mailoa Robert Bosch Research and Technology Center CambridgeMA 02139USA Northwestern University EvanstonIL 60208USA Harvard School of Engineering and Applied Sciences CambridgeMA 02138USA

Recently,machine learning(ML)has been used to address the computational cost that has been limiting ab initio molecular dynamics(AIMD).Here,we present GNNFF,a graph neural network framework to directly predict atomic forces from automatically extracted features of the local atomic environment that are translationally-invariant,but rotationally-covariant to the coordinate of the *** demonstrate that GNNFF not only achieves high performance in terms of force prediction accuracy and computational speed on various materials systems,but also accurately predicts the forces of a large MD system after being trained on forces obtained from a smaller ***,we use our framework to perform an MD simulation of Li7P3S11,a superionic conductor,and show that resulting Li diffusion coefficient is within 14%of that obtained directly from *** high performance exhibited by GNNFF can be easily generalized to study atomistic level dynamics of other material systems.

关键词： neural AIMD dynamics

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Image-guided conservative management of right colonic diverticulitis

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World Journal of Gastroenterology 2009年第46期15卷 5838-5842页

作者： Sun Jin park Sung II Choi Suk Hwan Lee Kil yeon Lee Department of Surgery Kyung Hee University School of Medicine

AIM： To study the clinical outcomes of medical therapy in patients with right colonic diverticulitis. METHODS： The records of 189 patients with right colonic diverticulitis which was finally diagnosed by computed tomography, ultrasonography, or operative findings were retrospectively reviewed. RESULTS： Of the 189 patients hospitalized for right colonic diverticulitis, the stages of diverticulitis by a modified Hinchey classification were 26 patients （13.8%） in stage 0, 139 patients （73.5%） in stage I a, 23 patients （12.2%） in stage I b, and 1 patient （0.5%） in stage Ⅲ. Medical therapy was undertaken in 185 of 189 patients （97.9%）. One hundred and eighty three of 185 patients were successfully treated with bowel rest and antibiotics. Two patients in stage I b required a resection or surgical drainage because of an inadequate response to conservative treatment. Recurrent diverticulitis developed in 15 of 183 patients （8.2%） who responded to medical therapy. All 15 patients who suffered a second attack had uncomplicated diverticulitis, and were successfully treated with medical ***： Our results indicate that right colonic diverticulitis is essentially benign and image-guided conservative treatment is primarily required.

关键词： Ascending colon Cecum Medical therapy Colonic diverticulitis

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Single port laparoscopic right hemicolectomy with D3 dissection for advanced colon cancer

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World Journal of Gastroenterology 2010年第2期16卷 275-278页

作者： Sung Il Choi Kil yeon Lee Sun Jin park Suk-Hwan Lee Department of Surgery School of MedicineKyung Hee University#1 Hoegi-dong Dongdaemun-guSeoul 130-702 South Korea

We report the first case of single port laparoscopic right hemicolectomy for advanced colon *** abdominal 3 cm length incision was made via the umbilicus.A small wound retractor and a surgical glove were used as a single *** soft tissue anterior to the superior mesenteric vein was completely removed and D3 lymph node dissection was *** total operative time was 180 min with minimal blood loss (<50 mL).The size of the tumor was 5 cm×3 cm and its tumor stage was ***-nine lymph nodes were harvested and none were *** believe that single port surgery for colon cancer is a feasible and safe procedure with surgical results comparable to conventional laparoscopic procedures.

关键词： Single port laparoscopic surgery Colon cancer D3 lymph node dissection

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