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Journal of Materials Science & Technology 2022年第16期111卷 99-110页

作者： Vioni Dwi Sartika won seok choi Gwanghyo choi Jaewook Han Sung-Jin Chang won-seok Ko Blazej Grabowski Pyuck-Pa choi Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea Gangwon Regional Division Korea Institute of Industrial TechnologyGangwon 25440Republic of Korea Division of Measurement and Analysis National Nanofab CenterDaejeon 34141Republic of Korea School of Materials Science and Engineering University of UlsanUlsan 44610Republic of Korea Institute for Materials Science University of StuttgartPfaffenwaldring 5570569 StuttgartGermany

We report laser cladding of pure titanium on a CoCrMo alloy using directed energy *** electron microscopy,the microstructural evolution upon varying the process parameters,especially laser power and powder feed rate,was investigated in relation to crack *** layers showing dilution rates of more than 5%contained cracks due to the formation of the brittle Co_(2)Ti intermetallic *** observed cracks could be ascribed to a mismatch in thermal expansion and a resulting stress of more than 440 MPa acting on the Co_(2)Ti phase,as determined by density functional theory and ***,an excess laser energy caused chemical inhomogeneity and unmelted Ti powder particles,while a deficient laser energy resulted in a lack of *** cracks nor partially melted powders were observed for a powder feed rate of 3 g/min and a laser power of 225–300 W,for which the dilution rate was minimized to less than 5%.For such samples,the cladding layers comprised pureα-Ti and a uniform CoT i interface with Co_(2)Ti islands.

关键词： Additive manufacturing Dissimilar metal joining Titanium Cobalt-based alloy

Decomposition behavior of yttria-stabilized zirconia and its effect on directed energy deposited Ti-based composite material

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Journal of Materials Science & Technology 2022年第17期112卷 138-150页

作者： Gwanghyo choi won seok choi Yoon Sun Lee Dahye Kim Ji Hyun Sung Seungjun An Chang-seok Oh Amine Hattal Madjid Djemai Brigitte Bacroix Guy Dirras Pyuck-Pa choi Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea 3D Additive Manufacturing Application Tech.Center Korea Institute of Industrial TechnologyDaegu 42994Republic of Korea InssTek Co. Daejeon 04763Republic of Korea Korea Institute of Materials Science 797 ChangwondaeroChangwon 51508Republic of Korea UniversitéSorbonne Paris Nord Laboratoire des Sciences des Procédés et des MatériauxLSPMCNRSUPR 3407F-93430VilletaneuseFrance Z3Dlab Parc Technologique26 Rue des SablonsMontmagny 95360France CNRS UPR3407Laboratoire des Sciences des Procédés et des MatériauxLSPMUniversitéSorbonne Paris NordF-93430VilletaneuseFrance

We report on the microstructure and the strengthening mechanisms of additively manufactured parts fabricated by directed energy deposition of Ti-6Al-4V(Ti64)powders blended with yttria-stabilized zirconia(YSZ)*** specimens showed refined microstructures as compared to bare as-deposited Ti64,where theαand columnar priorβgrain sizes decreased with increasing YSZ *** YSZ nanoparticles decomposed during the deposition process and led to the formation of yttrium oxide and some excess oxygen in the Ti64 *** decrease in the sizes of the priorβgrains could be attributed to the increasing amount of dissolved oxygen and yttrium,which promoted constitutional ***,the reduction in the size of theαgrains could be ascribed to a shift of the onset of theβ→α+βtransformation to a higher temperature and shorter time with increasing concentration of dissolved ***,the contributions of the underlying strengthening mechanisms for the as-deposited specimens were quantitatively determined.

关键词： Additive manufacturing Directed energy deposition Metal matrix composites Titanium alloys Yttrium-stabilized zirconia

Adaptive Step Size Control of LMS-based Interference Cancellation for ICS Repeater in Wibro Environment

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Journal of Measurement Science and Instrumentation 2010年第1期1卷 98-102页

作者： Jeong-gon KIM won-geon BAE won-seok choi Dept.of Electronic Engineering Korea Polytechnic UniversityKyunggi-Do 429-793Korea

The use of repeater for the support of high rate data trans- mission and the extension of cell coverage is imperative for the Wibro system, which based on the IEEE 802.16e standardization. Generally, if the separation between transmitting and receiving antennas is not sufficient, the oscillation of repeater and the interference due to the feedback signals from original transmitted signal may be oectLrr. Hence, the Interference Cancellation System （ICS） should be implemented as the important part of the repeater system for the mobile cellular systems in order to eliminate unwanted signals from the corrupted signals in the receiver. In this paper, we propose an adaptive technique for the Least Mean Square（LMS）-based interference cancellation methods by changing the step size according to the variation of channel envirorauent in onter to improve the performance degradation which occta-rs by using the fixed step size approach. Simulation results show that the proposed scheme attains a little lower Ber Error Rate（BER） performance and much faster convergence speed compared to the conventional LMS-based interference cancellation techniques. The proposed scheme can be applied to other Orthogonal Frequency Division Multiple（OFDM）-based cellular systenas and also be expected to achieve a similar performance improvement to IMT-advanced system, which is called as the next generation mobile communication standards.

关键词： Wibro mobile communication repeater adaptive inter-ference cancellation

Comparison of computed tomography findings between bacteremic and non-bacteremic acute pyelonephritis due to Escherichia coli

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World Journal of Radiology 2016年第4期8卷 403-409页

作者： Seon Jung Oh Bo-Kyung Je Seung Hwa Lee won seok choi Doran Hong Sung-Bum Kim Department of Radiology Korea University Hospital Department of Internal Medicine Korea University Hospital Department of Internal Medicine B-um Hospital

AIM:To identify computed tomography(CT)findings that are associated with the presence of bacteremia in patients with acute pyelonephritis(APN)due to Escherichia coli(***).METHODS:The clinical data and contrast-enhanced CT findings of 128 patients who were diagnosed with APN due to *** and showed renal abnormality on contrast-enhanced CT between January 2003 and November 2013 were retrospectively *** patients were divided into two groups according to the presence of bacteremia:The bacteremia group and the non-bacteremia *** abnormality on contrast-enhanced CT were categorized into 5 renal and 4 extrarenal CT findings and compared between the two groups using the χ~2 test and multivariate logistic ***:Among the 128 patients,34 patients(26.6%)were classified into the bacteremia group and 94 patients(73.4%)into the non-bacteremia *** was no statistically significant difference in gender between the two groups(P = 0.09),but the age of thepatients in the bacteremia group was higher than that of the patients in the non-bacteremia group(P < 0.01).Compared to the non-bacteremia group,1 renal CT finding such as urothelial thickening and 3 extrarenal CT findings such as diffuse peritoneal thickening,cystitis and pulmonary congestion were more frequently observed in the bacteremia group with statistical *** logistic regression analysis revealed that CT findings,including urothelial thickening,diffuse peritoneal thickening,cystitis and pulmonary congestion were suggested as the predictive CT findings of bacteremic ***:On CT,urothelial thickening,diffuse peritoneal thickening,cystitis,and pulmonary congestion are more frequently observed in patients with bacteremic APN due to ***.

关键词： Escherichia coli Pyelonephritis Urinary tract infections Bacteremia Multidetector computed tomography

Role of kaempferol to increase bioavailability and pharmacokinetics of nifedipine in rats

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Chinese Journal of Natural Medicines 2019年第9期17卷 690-697页

作者： PARK Ji-won choi Jin-seok Hazardous Substances Analysis Division Gwangju Regional Office of Food and Drug SafetyGwangju 61012Republic of Korea Department of Medical Management Chodang UniversityJeollanam-do 58530Republic of Korea

Herein,the purpose of this study is to evaluate the effects of kaempferol on bioavailability and pharmacokinetics of nifedipine and its metabolite dehydronifedipine in *** experimental design is based on with or without kaempferol in the oral and intravenous administration of nifedipine in ***,the pharmacokinetic parameters including nifedipine and dehydronifedipine were evaluated in *** in vitro studies of kaempferol were investigated on P-glycoprotein(P-gp)and cytochrome P450(CYP)3A4 *** reduced a 50%inhibitory concentration(IC50)of 8.6μmol·L-1 on CYP3A4 enzyme ***,kaempferol clearly improved the cell internalization of rhodamine-123 in MCF-7/ADR cells overexpressing *** on increased concentrations of kaempferol,the areas under the plasma concentration–time curve(AUC0-∞)and the peak concentration(Cmax)of nifedipine were increased after oral and intravenous ***,the absolute bioavailability(AB)and relative bioavailability(RB)of nifedipine in the presence of kaempferol was significantly higher than those of the control group after oral and intravenous *** of bioavailability of nifedipine by kaempferol may be mainly because of the inhibition of the P-gp-mediated efflux transporter in the small intestine and CYP3A4-mediated metabolism in the small intestine or liver,or both.

关键词： Nifedipine Kaempferol CYP3A4 P-gp Pharmacokinetics Bioavailability

Reaction mechanism and additional lithium storage of mesoporous MnO_(2) anode in Li batteries

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Journal of Energy Chemistry 2021年第2期30卷 276-284,I0010页

作者： Jaesang Yoon Woosung choi Taewhan Kim Hyunwoo Kim Yun seok choi Ji Man Kim won-Sub Yoon Department of Energy Science Sungkyunkwan UniversitySuwon 16419South Korea Department of Chemistry Sungkyunkwan UniversitySuwon 16419South Korea

Nanostructured transition metal oxides,employed as anode materials for lithium-ion batteries,exhibit a higher capacity than the theoretical capacity based on the conversion *** date,the reasons behind this phenomenon are *** the one-step evolution of anode material for lithium-ion batteries,it is essential to understand the lithium storage reaction mechanism of the anode ***,we provide a detailed report on the lithium storage and release mechanism of MnO2,using synchrotron-based X-ray techniques.X-ray diffraction and X-ray absorption spectroscopy results indicate that during the first discharge,MnO2 is reduced in the order of MnO2→LixMnO2(1

关键词： Mesoporous MnO_(2) Reaction mechanism Electrolyte-derived surface layer Synchrotron-based X-ray techniques Anode Li battery

MicroRNA miR-252-5p regulates the Notch signaling pathway by targeting Rab6 in Drosophila wing development

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Insect Science 2023年第5期30卷 1431-1444页

作者： Do-Hwan Lim Min-seok choi Ji won Jeon Young Sik Lee School of Systems Biomedical Science Soongsil UniversitySeoulRepublic of Korea College of Life Sciences and Biotechnology Korea UniversitySeoulRepublic of Korea Institute of Animal Molecular Biotechnology Korea UniversitySeoulRepublic of Korea

The Notch signaling pathway plays a central role in the development of various ***,dysregulation of microRNAs(miRNAs),which are crucial regulators of gene expression,can disrupt signaling pathways at all stages of *** Notch signaling is involved in wing development in Drosophila,the mechanism underlying miRNA-based regulation of the Notch signaling pathway is ***,we report that loss of Drosophila miR-252 increases the size of adult wings,whereas the overexpression of miR-252 in specific compartments of larval wing discs leads to patterning defects in the adult *** miR-252 overexpression-induced wing phenotypes were caused by aberrant Notch signaling with intracellular accumulation of the full-length Notch receptor during development,which could be due to defects in intracellular Notch trafficking associated with its recycling to the plasma membrane and autophagy-mediated ***,we identified Rab6 as a direct target of miR-252-5p;Rab6 encodes a small Ras-like GTPase that regulates endosomal trafficking *** with this finding,RNAi-mediated downregulation of Rab6 led to similar defects in both wing patterning and Notch ***,co-overexpression of Rab6 completely rescued the wing phenotype associated with miR-252 overexpression,further supporting that Rab6 is a biologically relevant target of miR-252-5p in the context of wing ***,our data indicate that the miR-252-5p-Rab6 regulatory axis is involved in Drosophila wing development by controlling the Notch signaling pathway.

关键词： Drosophila miR-252-5p Notch signaling Rab6 wing development

Understanding the physical metallurgy of the CoCrFeMnNi high-entropy alloy:an atomistic simulation study

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npj Computational Materials 2018年第1期4卷 662-670页

作者： won-Mi choi Yong Hee Jo seok Su Sohn Sunghak Lee Byeong-Joo Lee Department of Material Science and Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea

Although high-entropy alloys(HEAs)are attracting interest,the physical metallurgical mechanisms related to their properties have mostly not been clarified,and this limits wider industrial applications,in addition to the high alloy *** clarify the physical metallurgical reasons for the materials phenomena(sluggish diffusion and micro-twining at cryogenic temperatures)and investigate the effect of individual elements on solid solution hardening for the equiatomic CoCrFeMnNi HEA based on atomistic simulations(Monte Carlo,molecular dynamics and molecular statics).A significant number of stable vacant lattice sites with high migration energy barriers exists and is thought to cause the sluggish *** predict that the hexagonal close-packed(hcp)structure is more stable than the face-centered cubic(fcc)structure at 0 K,which we propose as the fundamental reason for the micro-twinning at cryogenic *** alloying effect on the critical resolved shear stress(CRSS)is well predicted by the atomistic simulation,used for a design of non-equiatomic fcc HEAs with improved strength,and is experimentally *** study demonstrates the applicability of the proposed atomistic approach combined with a thermodynamic calculation technique to a computational design of advanced HEAs.

关键词： alloy alloying entropy

Pediatric schwannoma of the tongue:A case report and review of literature

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World Journal of Clinical Cases 2021年第24期9卷 7212-7217页

作者： Chang Bin Yun Young-Mo Kim Jeong-seok choi Ji won Kim Department of Otorhinolaryngology-Head and Neck Surgery Inha University College of MedicineIncheon 22212South Korea

BACKGROUND Neurogenic tumors account for about ten percent of all tumors of childhood,and benign tumor originating from Schwann cells is rare in peripheral *** of the tongue is quite rare in *** SUMMARY We present the case of an 8-year-old male with schwannoma in the anterolateral *** mass was slow-growing for one year with no pain and *** underwent transoral mass excision under general *** examination revealed a smooth surfaced,17 mm×14 mm×7 mm sized,encapsulated nodule with a clear resection *** of the tongue was confirmed by the pathological *** reported no motor or sensory change,such as dysgeusia or paresthesia,or phonation difficulty during postoperative 12 mo *** Schwannoma of the tongue is a rare benign neoplasm in *** a painless firm mass is encountered in the tongue of a child,solid tumors like schwannoma should be considered in the differential diagnosis.

关键词： Schwannoma Tongue Child Pediatric Neurogenic Tumor Case report