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Dynamic deformation behavior and microstructural evolution during high-speed rolling of Mg alloy having non-basal texture

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Journal of Materials Science & Technology 2019年第4期35卷 473-482页

作者： Sang-hoon Kim Jeong Hun lee Chong Soo lee Jonghun Yoon Sung Hyuk Park School of Materials Science and Engineering Kyungpook National University Ulsan Regional Division Korea Institute of Industrial Technology Graduate Institute of Ferrous Technology Pohang University of Science and Technology Department of Mechanical Engineering Hanyang University

The dynamic deformation behaviors and resultant microstructural variations during high-speed rolling(HSR) of a Mg alloy with a non-basal texture are investigated. To this end, AZ31 alloy samples in which the basal poles of most grains are predominantly aligned parallel to the transverse direction(TD) are subjected to hot rolling with different reductions at a rolling speed of 470 m/min. The initial grains with a TD texture are favorable for {10–12} twinning under compression along the normal direction(ND); as a result, {10–12} twins are extensively formed in the material during HSR, and this consequently results in a drastic evolution of texture from the TD texture to the ND texture and a reduction in the grain size. After the initial grains are completely twinned by the {10–12} twinning mechanism, {10–11} contraction twins and {10–11}-{10–12} double twins are formed in the {10–12} twinned grains by further *** the contraction twins and double twins have crystallographic orientations that are favorable for basal slip during HSR, dislocations easily accumulate in these twins and fine recrystallized grains nucleate in the twins to reduce the increased internal strain energy. Until a rolling reduction of 20%, {10–12}twinning is the main mechanism governing the microstructural change during HSR, and subsequently,the microstructural evolution is dominated by the formation of contraction twins and double twins and the dynamic recrystallization in these twins. With an increase in the rolling reduction, the average grain size and internal strain energy of the high-speed-rolled(HSRed) samples decrease and the basal texture evolves from the TD texture to the ND texture more effectively. As a result, the 80% HSRed sample, which is subjected to a large strain at a high strain rate in a single rolling pass, exhibits a fully recrystallized microstructure consisting of equiaxed fine grains and has an ND basal texture without a TD texture component.

关键词： Magnesium alloy High-speed rolling Texture Dynamic recrystallization Twinning

Direct dynamic-simulation approach to trajectory optimization

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Chinese Journal of Aeronautics 2021年第10期34卷 6-19页

作者： Sung Wook HUR Seong Han lee Yong Hyeon NAM Chang-joo KIM Department of Aerospace Information Engineering Konkuk UniversitySeoul 05029Republic of Korea

This paper proposes a new direct method for an efficient trajectory optimization using the point that the dynamics of a deterministic system are uniquely determined by initial states and controls imposed over the time horizon of *** effectively implement this concept,the Hermite spline is adopted to interpolate the continuous controls and the system dynamics are integrated with corresponding control parameters in *** a result,the optimal control problem can be transcribed into a nonlinear programming problem which has no dynamic equality constraints and no intermediate states in its design *** addition,the paper proposes an efficient recursive Jacobian estimation technique and introduces a Jacobian transformation matrix to straightforwardly handle the general state *** properties of the present method are thoroughly investigated through its applications to the trajectory optimization for a soft lunar landing from a parking orbit,including the detailed analyses for the de-orbiting *** computed results are compared with those using the pseudo-spectral method to demonstrate an extreme outperformance of the proposed method in the aerospace applications over the traditional direct method.

关键词： Trajectory optimization Direct method Hermite spline interpolation Pseudo-spectral integrator Soft lunar landing

Assessment of incidental focal colorectal uptake by analysis of fluorine-18 fluorodeoxyglucose positron emission tomography parameters

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World Journal of Clinical Cases 2022年第17期10卷 5634-5645页

作者： Haejun lee Kyung-hoon Hwang Kwang An Kwon Department of Nuclear Medicine Gachon University College of MedicineGil Medical CenterIncheon 21565South Korea Department of Gastroenterology Gachon University College of MedicineGil Medical CenterIncheon 21565South Korea

BACKGROUND Colon and rectal cancers are among the top five cancers worldwide in terms of their incidence and mortality *** the treatment options for cure include surgery even in specific advanced-stage cases,the early detection of lesions is important for applying active treatment ***-18 fluorodeoxyglucose(F-18 FDG)positron emission tomography/computed tomography(PET/CT)is an established imaging study for many types of cancers;however,physiologic uptake in the gastrointestinal tract is a frequent finding and may interfere with lesion ***,as unexpectedly observed focal colorectal F-18 FDG uptake may harbor malignant lesions,further examination must not be *** To assess the clinical implications of unexpected focal colorectal F-18 FDG uptake by analyzing FDG PET *** A total of 15143 F-18 FDG PET/CT scans performed at our hospital between January 2016 and September 2021 were retrospectively reviewed to identify incidentally observed focal colorectal FDG ***,83 regions showing focal colorectal FDG uptake with final histopathological reports from 80 patients(45 men and 35 women with mean ages of 66.9±10.7 years and 63.7±15.3 years,respectively)were eligible for inclusion in the present *** focal hypermetabolic colorectal region was classified as malignant,premalignant,or benign according to the histopathological *** parameters such as maximum and peak standardized uptake value(SUVmax and SUVpeak),metabolic tumor volume(MTV),mean SUV of the metabolic tumor volume(mSUVmtv),and total lesion glycolysis(TLG)were measured or calculated for the corresponding hypermetabolic *** and nonparametric statistical comparisons of these parameters were performed among the three *** operating characteristic curves were plotted to identify cut-off *** The detection rate of incidental focal colorectal uptake was 0.53%(80/15,143).Of the 83 regions with unexpected fo

关键词： Colorectal Incidental Fluorine-18 fluorodeoxyglucose Positron emission tomography/computed tomography Standardized uptake value

Endoscopic transcystic stent placement for an intrahepatic abscess due to gallbladder perforation

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World Journal of Gastroenterology 2007年第9期13卷 1458-1459页

作者： Myung Soo Kang Do Hyun Park Ki Du Kwon Jeong hoon Park Suck-Ho lee Hong-Soo Kim Sang-Heum Park Sun-joo Kim Division of Gastroenterology Department of Internal MedicineSoon Chun Hyang University Cheonan HospitalCheonan Korea

Perforation of the gallbladder with cholecystohepatic communication is a rare cause of liver abscess. Because it is a rare entity, the treatment modality has not been fully established. We report for the first time a patient with an intrahepatic abscess due to gallbladder perforation successfully treated by endoscopic stent placement into the gallbladder who had a poor response to continuous percutaneous drainage.

关键词： Liver abscess Gallbladder perforation Endoscopic stent placement Cholecystohepatic communication

Radiolarians from the Pohang Basin,Southeast Korea and Paleoceanographic Implications

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Acta Geologica Sinica(English Edition) 2012年第6期86卷 1426-1433页

作者： Young-Suk BAK Jong-Deock lee Hyesu YUN Jinyong OH Seong-joo lee Kyungpook National University Chonbuk National University Chungnam National University

We identified a total of 101 species and two subspecies of radiolarians belonging to 56 genera from 95 samples collected from the Hagjeon and Duho Formations in the Pohang Basin of the southeastern Korean Peninsula. On the basis of the biostratigraphic range of Cyrtocapsella cornuta and Theocorys redondoensis, the depositional period of the upper Hagjeon and lowest Duho Formations was determined to be early to late Middle Miocene. The occurrence of deep-dwelling radiolarians indicates that the paleobathymetry seems to become gradually progressing toward an upper bathyal environment in the middle part of the Hagjeon Formation. However, we prefer to accept another interpretation for the occurrence of deep-sea indicators in the Hagjeon and the lowest part of the Duho Formations, and consider the presence of a region of upwelling cold water that might have simulated a deep-water environment in relatively shallow water. This interpretation is based on the present upwelling of a cold-water mass off the southeast coast of Korea, the occurrence of upwelling microfossils from the Pohang Basin, and the effect of the closing of the Korea Strait approximately 15 Ma. We also considered that the uppermost part of the studied section represents a shallow-water environment.

关键词： radiolarian depositional environment upweHing Pohang Basin

Fabrication of SAW Sensor for Detecting Chemical Agent

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稀有金属材料与工程 2006年第A3期35卷 433-435页

作者： J H lee B S joo J S Huh D D lee School of Electronic & Electrical Engineering Kyungpook National UniversityKorea Dept.of Materials Science and Metallurgy Kyungpook National UniversityKorea

SAW sensors using five different types of polymer to detect of chemical agents(DMMP,CH_3CN,CH_2Cl_2,DCP) have been fabricated and its gas response characteristics were extensively *** polymers used as the sensing material are polyisobutylene(PIB),polyepichlorohydrin(PECH),polydimethylsiloxane(PDMS),polyisoprene(PIP)and polybutadiene(PBD).Their thin films were coated on quartz substrate by spin coating *** types of simulants gases,dimethylmethylphosphonate(DMMP),acetonitrile(CH_3CN)and dichloromethane(CH_2Cl_2),dichloropentane(DCP)were used as target gases,instead of the real nerve,blood,choking and vesicant *** spin coating of PIB and PECH,the substrates were heated to 65℃with N_2 flow for 1 h to remove the cyclohexane and ethylacetate which was used as solvent. PDMS was heated to 75℃with N_2 flow for 2 h to remove the ethylacetate which was used as *** and PIP on the substrate were heated to 60℃with N_2 flow for 1 h to remove the benzen which was used as *** sensing characteristics of the SAW sensors were measured by using E-5061A network analyzer.

关键词： SAW DMMP CH3CN CH2Cl2 DCP polymer film

In-situ synthesis of TiC/Fe alloy composites with high strength and hardness by reactive sintering

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Journal of Materials Science & Technology 2018年第8期34卷 1397-1404页

作者： Junho lee Dongju lee Myung hoon Song Wonhyuk Rhee Ho Jin Ryu Soon Hyung Hong Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology291 Daehak-roYuseong-guDaejeon305-701Republic of Korea Department of Nuclear and Quantum Engineering Korea Advanced Institute of Science and Technology291 Daehak-roYuseong-guDaejeon305-701Republic of Korea Nuclear Materials Development Division Korea Atomic Energy Research Institute111 Daedeok-daero 989 Beon-gilYuseong-guDaejeon305-353Republic of Korea Daewha Alloytech Corporation 17-60Sanupdanji-gilMyeoncheon-myeonDangjin-siChungcheongnam-doRepublic of Korea

Fe alloy composites reinforced with in-situ titanium carbide （TIC） particles were fabricated by reactive sintering using different reactant C/Ti ratios of 0.8, 0.9, 1 and 1.1 to investigate the microstructure and mechanical properties ofin-situ TiC/Fe alloy composites. The microstructure showed that the in-situ syn- thesized TiC particles were spherical with a size of 1-3 }~m, irrespective of C/Ti ratio. The stoichiometry of in-situ TiC increased from 0.85 to 0.88 with increasing C/Ti ratio from 0.8 to 0.9, but remained almost unchanged for C/Ti ratios between 0.9 and 1.1 due to the same driving force for carbon diffusion in TiCx at the common sintering temperature. The in-situ TiC/Fe alloy composite with C[Ti ~ 0.9 showed improved mechanical properties compared with other C/Ti ratios because the presence of excess carbon （C/Ti = 1 and 1.1） resulted in unreacted carbon within the Fe alloy matrix, while insufficient carbon （C/Ti = 0.8） caused the depletion of carbon from the Fe alloy matrix, leading to a significant decrease in hardness. This study presents that the maximized hardness and superior strength of in-situ TiC/Fe alloy composites can be achieved by microstructure control and stoichiometric analysis of the in-situ synthesized TiC par- ticles, while maintaining the ductility of the composites, compared to those of the unreinforced Fe alloy. Therefore, we anticipate that the in-situ synthesized TiC/Fe alloy composites with enhanced mechanical properties have great potential in cutting tool, mold and roller material applications.

关键词： Metal matrix composites Sintering Mechanical properties Microstructures

Moxibustion Therapy in Traditional Mongolian Medicine

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Chinese Journal of Integrative Medicine 2018年第9期24卷 707-712页

作者： Tae-Hun Kim Do-hoon Kim Seong Gyu lee College of Korean Medicine Kyung Hee University Seoul 202447 Republic of Korea Department of Medical Classics and History Gachon University Seongnam 213120 Republic of Korea College of Humanities Dankook University Cheonan 231116 Republic of Korea

From the medical history of traditional Eastern Asian and Tibetan medicine, the origin and development of moxibustion seems to be closely related to Mongolia. To explore the current clinical practice of moxibustion in Mongolia, we visited a teaching hospital, the Traditional Medical Science, Technology and Production Corporation of Mongolia, in February 2014. Many types of moxibustion are found to be used, and various modalities and methods are practiced based on the principles of traditional Mongolian medicine. In particular, Mongolian drug moxibustion, which uses small butter-warmed bags packed with powdered aromatic herbs instead of moxa cones, is a unique moxibustion technique not found in other countries. In this paper, we introduce the clinical practice of moxibustion, specifically Mongolian drug moxibustion in Mongolia.

关键词： traditional Mongolian medicine moxibustion Mongolian drug moxibustion

Tamsulosin-induced life-threatening hypotension in a patient with spinal cord injury:A case report

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World Journal of Clinical Cases 2022年第25期10卷 9142-9147页

作者： Jae Young lee Ho Seok lee Si-Bog Park Kyu hoon lee Rehabilitation Medicine Hanyang University HospitalSeoul 04763South Korea

BACKGROUND Tamsulosin,a selectiveα1-adrenergic receptor antagonist,is commonly used for treating neurogenic bladder in patients with spinal cord injury(SCI).No severe adverse events have been described with such tamsulosin *** our knowledge,we report the first case of severe life-threatening hypotension as an adverse effect of tamsulosin in a person with ***,we report this case to inform that this severe adverse effect of tamsulosin can occur when treating patients with *** SUMMARY A 59-year-old woman was diagnosed with cervical spinal cord myelopathy and was classified as American Spinal Injury Association Impairment Scale D,neurological level of injury *** she suffered from voiding difficulty due to neurogenic bladder,we prescribed *** vital signs remained stable,but occasional hypotensive symptoms followed *** reduced the dose of tamsulosin,but after administering tamsulosin for 9 d,she experienced lifethreatening hypotension with no evidence of hypovolemic shock,neurogenic shock,cardiogenic shock,or septic shock.A hypotensive condition induced by tamsulosin was the suspected cause,and her symptoms could be associated with adverse effects of *** symptoms resolved after stopping tamsulosin,and no other reason was found,we concluded that tamsulosin was the cause of her *** Caution for severe hypotension is needed when administering tamsulosin for neurogenic bladder in a patient with SCI.

关键词： Tamsulosin Neurogenic bladder Spinal cord injury Hypotension Vasovagal symptoms Case report