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Frontiers of Structural and Civil Engineering 2022年第4期16卷 506-514页

作者： Jinyoung YOON Byoung Il CHOI jae Hong kim Department of Structural Engineering Research Korea Institute of Civil Engineering and Building Technology(KICT)Goyang 10223Republic of Korea System Safety Research Department Korea Shipbuilding and Offshore EngineeringSeongnam 13591Republic of Korea Department of Civil and Environmental Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea

The cement dispersion performance of a polycarboxylate(PCE)-based superplasticizer is highly related to their adsorption behaviors as a function of *** study evaluated effects of PCEs on rheological properties of cementitious ***,characteristics of PCEs were characterized via permeation chromatography(GPC)and Fourier-transform infrared spectrometry(FT-IR).The adsorption behavior of single and blended PCEs on cementitious composites was identified using total organic carbon analyzer(TOC).Based on the measurement of PCE adsorption,the changes of rheological properties of cementitious materials as well as the number of dispersed cement particles were characterized using a rheometer and laser spectroscopy,*** experimental results support the systematic mechanism of PCE adsorption,cement dispersion,and the decrease in viscosity of cementitious materials.

关键词： adsorption polycarboxylate superplasticizer rheology dispersion

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Superelastic metastable Ti-Mo-Sn alloys with high elastic admissible strain for potential bio-implant applications

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Journal of Materials Science & Technology 2023年第32期163卷 45-58页

作者： Shuanglei Li jae H.kim Seung Won Kang jae Ho kim Tae-Hyun Nam Jong-Taek Yeom Titanium Alloys Department Metal Materials DivisionKorea Institute of Materials Science(KIMS)Changwon 51508Republic of Korea Department of Materials Engineering and Convergence Technology&Research Institute for Green Energy Convergence Technology(RIGET) Gyeongsang National University900 GazwadongJinjuGyeongnam 52828Republic of Korea

The demand for titanium alloys simultaneously having high elastic admissible strain and large recovery strain for bio-implant applications is ***-free Ti-based shape memory alloys are promising candidates for obtaining the required multifunctional *** this study,a wide content range of(0-15)wt%of low-cost,toxicity-free,and high-biocompatible Sn element was added to the Ti-8Mo(wt%)alloy to study its effect on the superelastic recovery and mechanical properties of biomedical Ti-Mo-Sn *** tailoring Sn content,desired multifunctional properties of high elastic admissible strain and room temperature superelasticity were achieved in the studied Ti-Mo-Sn *** was found that the increase in Sn content stabilized theβphase and a singleβphase was obtained at room temperature in Ti-8Mo-(13,15)Sn *** addition of Sn modified the lattice parameters of theα″martensite andβphase and affected the lattice deformation stain ofβ→α″.The lattice deformation strain along the[011]βdirection was found to be decreased by-0.26%/wt%*** room temperature superelasticity with a recovery strain of 3.1%and an elastic admissible strain of 1%was obtained in the Ti-8Mo-13Sn *** Sn content increased to 15 wt%,a high elastic admissible strain of 1.56%and a recovery strain of 2.0%were *** Ti-Mo-Sn alloys with excellent multifunctional properties are promising candidates for bio-implant applications.

关键词： Ti-Mo-Sn alloy Shape memory alloy Elastic admissible strain Elastic modulus Superelasticity

Origin of superior low-cycle fatigue resistance of an interstitial metastable high-entropy alloy

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Journal of Materials Science & Technology 2022年第20期115卷 115-128页

作者： Seyed Amir Arsalan Shams jae Wung Bae jae Nam kim Hyoung Seop kim Taekyung Lee Chong Soo Lee Graduate Institute of Ferrous Technology Pohang University of Science and TechnologyPohang 37673Republic of Korea Department of Materials Science and Engineering Pohang University of Science and TechnologyPohang 37673Republic of Korea School of Mechanical Engineering Pusan National UniversityBusan 46241Republic of Korea

In this study, the deformation behaviors and related microstructural evolutions were investigated in either monotonic or cyclic deformation modes in an interstitial metastable high-entropy alloy. These investigations aimed to reveal the mechanisms underlying the superior low-cycle fatigue(LCF) life of this alloy.A thermomechanical process was applied to induce fine-grained(FG) and coarse-grained(CG) microstructures in Fe–30Mn–10Co–10Cr–0.4C(atomic percentage) alloy. Their superior combination of strength and ductility was attributed to the appearance of deformation-induced ε-martensite and the presence of carbon. The CG alloy showed a greater volume fraction of ε-martensite than the FG alloy in the monotonic deformation mode, and vice versa in the cyclic mode. Such a disparity was interpreted in light of the back-stress effect of the relaxed γ-grain boundaries in the latter mode. Meanwhile, the γ-to-ε phase transformation under cyclic loading at low strain amplitudes(0.4%) barely led to an improved fatigue life as compared with that at higher strain amplitudes(≥ 0.55%). The high reversibility of partial dislocation motions under cyclic loading and delaying the formation of dislocation cells through the martensitic transformation could explain why the alloys investigated in this study exhibited a superior LCF life compared with high-entropy alloys reported in previous studies.

关键词： High-entropy alloy Transformation-induced plasticity Monotonic deformation Cyclic deformation Low-cycle fatigue Stacking faults

Implementation of configuration dependent stiffness proportional damping for the dynamics of rigid multi-block systems

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Earthquake Engineering and Engineering Vibration 2003年第1期2卷 87-98页

作者： Yun Byeong Chae jae Kwan kim R & D Division Chungsuk Engineering57Garak-dongSongpa-kuSeoul138-802Korea Assistant Engineer School of Civil Urban and Geosystem EngineeringSeoul National UniversitySeoul151-742Korea Associate Professor

The distinct element method(DEM)has been used successfully for the dynamic analysis of rigid block sys- *** of many difficulties associated with DEM is modeling of *** this paper,new procedures are proposed for the damping modeling and its numerical implementation in distinct element analysis of rigid muhi-block *** stiff- ness proportional damping is constructed for the prescribed damping ratio,based on the non-zero fundamental frequency ef- fective during the time interval while the boundary conditions remain essentially *** this time interval,the funda- mental frequency can be estimated without complete eigenvalue *** damping coefficients will vary while the damp- ing ratio remains the same throughout the entire analysis.A new numerical procedure is developed to prevent unnecessary energy loss that can occur during the separation *** procedures were implemented in the development of the dis- tinet element method for the dynamic analyses of piled multi-block *** analysis results |or the single-block and two-block systems were in a good agreement with the analytic *** to the seismic analyses of piled four- block systems revealed that the new procedures can make a significant difference and may lead to much-improved results.

关键词： multi-block systems stiffness proportional damping rocking impact distinet element method rigid body dynamics

Segregation of voiced and unvoiced components from residual of speech signal

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Journal of Central South University 2012年第2期19卷 496-503页

作者： JO Cheol-woo kim jae-hee School of Mechatronics Changwon National University

In conventional source-filter models, voiced and unvoiced components were considered independently. However, in practice it was difficult to separate the source into two parts. An actual source consists of a mixture of two sources and the ratio varies according to the content or the intention of speaker. It had been investigated to separate the voiced and unvoiced components for different source models. Source signals were modeled based on the residual signal measured from inverse filtering. Three different source models were assumed. The parameters of each model were optimized for the original speech signal using a genetic algorithm. The resulting parameters were compared in terms of the mel-cepstral distance to the original signal, the spectrogram and the spectral envelope from the synthesized signal. The optimization method achieves an improvement of 15% for the Klatt model, but there is little improvement in the modified residual case.

关键词： voice source model synthesis optimization genetic algorithm

Large gastric hamartomatous inverted polyp accompanied by advanced gastric cancer:A case report

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World Journal of Clinical Cases 2023年第28期11卷 6967-6973页

作者： Gyerim Park Jihye kim Sung hak Lee Younghoon kim Department of Pathology Seoul St.Mary's HospitalCollege of MedicineThe Catholic University of KoreaSeoul 06591South Korea Department of Internal Medicine CHA Gangnam Medical CenterCHA UniversitySeoul 06135South Korea Center for Health Promotion and Optimal Aging Seoul National University HospitalSeoul 03080South Korea

BACKGROUND Gastric hamartomatous inverted polyps(GHIPs)are benign polyps of the gastric submucosal *** there are 52 reported cases in the English *** to a literature review,approximately 27%of GHIPs show a coexisting *** SUMMARY A 66-year-old man was referred to our institution with ulcerative lesions detected on esophagogastroduodenoscopy(EGD)during a regular *** medical findings were *** lesions had borderline histologic features that could not exclude malignancy and were followed up with three EGDs and biopsies at intervals of 3 *** latest biopsy was revealed as an adenocarcinoma.A total gastrectomy was performed to remove the *** surgical specimen revealed a 6.9 cm×4.5 cm sized GHIP with a coexisting 1.6 cm sized well-differentiated adenocarcinoma which extended to the muscularis *** malignancy did not originate from the GHIP but showed an *** A large GHIP,which was unusually presented as an ulcerative lesion,was surgically removed,and was accompanied by advanced gastric *** follow-up and thorough examinations of ulcerative lesions with equivocal biopsy have resulted in appropriate diagnosis and ***,aggressive intervention may be beneficial if GHIP is suspected.

关键词： Gastric hamartomatous inverted polyp Advanced gastric cancer Total gastrectomy Case report

A nanofilter composed of carbon nanotube-silver composites for virus removal and antibacterial activity improvement

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Journal of Environmental Sciences 2016年第4期28卷 275-283页

作者： Jun Pyo kim jae Ha kim Jieun kim Soo No Lee Han-Oh Park Nano Development Team Bioneer Corporation Daejeon 306-220 Republic of Korea

We have developed a new nanofilter using a carbon nanotube-silver composite material that is capable of efficiently removing waterborne viruses and *** nanofilter was subjected to plasma surface treatment to enhance its flow rate,which was improved by approximately 62%.Nanoscale pores were obtained by fabricating a carbon nanotube network and using nanoparticle fixation technology for the removal of *** pore size of the nanofilter was approximately 38 nm and the measured flow rate ranged from 21.0 to 97.2 L/（min·m^2）under a pressure of 1–6 kgf/cm^2 when the amount of loaded carbon nanotube-silver composite was 1.0 mg/cm^*** nanofilter was tested against Polio-,Noro-,and Coxsackie viruses using a sensitive real-time polymerase chain reaction assay to detect the presence of viral particles within the *** trace of viruses was found to flow through the nanofilter with carbon nanotube-silver composite loaded above 0.8 mg/cm^***,the surface of the filter has antibacterial properties to prevent bacterial clogging due to the presence of 20-nm silver nanoparticles,which were synthesized on the carbon nanotube surface.

关键词： Carbon nanotube Silver nanoparticle Virus removal Nanofilter Water purification

Development of two-axis control index table driven by direct drive motors

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Journal of Central South University 2011年第6期18卷 1962-1968页

作者： kim jae-hyun LEE Choon-man School of Mechatronics Changwon National University

The stability and reliability of a tilting index table should be considered at the design stage. A design method for the lightweight and improvement of the stability of the structure in a tilting index table was proposed using a commercial analysis program, ANSYS Workbench 12, by analyzing the static-thermal characteristics of the developed high-accuracy tilting index table at its design stage. The results of the performed structural analysis show that the maximum stress is generated at the stock tail part. An optimum design for the stock tail part was carried out to reduce the maximum stress and deformation. Also, the design variables were determined by considering the support of the stock tail part for the C-axis body. In the comparison of the results before and after the optimization, the maximum deformation and stress are improved by 2.8% and 8%, respectively.

关键词： tilting index table structural analysis modal analysis thermal analysis optimum design

Physical Experiments to Investigate the Effects of Street Bottom Heating and Inflow Turbulence on Urban Street-Canyon Flow

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Advances in Atmospheric Sciences 2005年第2期22卷 230-237页

作者： jae-Jin kim Jong-Jin BAIK Climate Environment System Research Center Seoul National University Seoul 151-742 KoreaSchool of Earth and Environmental Sciences Seoul National University Seoul 151-742 Korea

The effects of street bottom heating and inflow turbulence on urbanstreet-canyon flow are experimentally investigated using a circulating water channel. Threeexperiments are carried out for a street canyon with a street aspect ratio of 1. Results from eachexperiment with bottom heating or inflow turbulence are compared with those without bottom heatingand appreciable inflow turbulence. It is demonstrated that street bottom heating or inflowturbulence increases the intensity of the canyon vortex. A possible explanation on how street bottomheating or inflow turbulence intensifies the canyon vortex is given from a fluid dynamicalviewpoint.

关键词： urban street-canyon flow street bottom heating inflow turbulence circulating water channel

Varifocal occlusion in an optical see-through near-eye display with a single phase-only liquid crystal on silicon

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Photonics Research 2024年第4期12卷 833-853页

作者： WOONGSEOB HAN jae-WON LEE JUNG-YEOP SHIN MYEONG-HO CHOI hak-RIN kim jae-HYEUNG PARK Department of Electrical and Computer Engineering Inha University100 Inha-roMichuhol-guIncheon 22212Republic of Korea School of Electronic and Electrical Engineering Kyungpook National University80 Daehak-roBuk-guDaegu 41566Republic of Korea School of Electronics Engineering Kyungpook National University80 Daehak-roBuk-guDaegu 41566Republic of Korea Department of Information and Communication Engineering Inha University100 Inha-roMichuhol-guIncheon 22212Republic of Korea

We propose a near-eye display optics system that supports three-dimensional mutual *** exploiting the polarization-control properties of a phase-only liquid crystal on silicon (LCoS),we achieve real see-through scene masking as well as virtual digital scene imaging using a single *** depth control of the real scene mask and virtual digital image is also achieved by using a focus tunable lens (FTL) pair of opposite *** proposed configuration using a single LCoS and opposite curvature FTL pair enables the self-alignment of the mask and image at an arbitrary depth without distorting the see-through view of the real *** verified the feasibility of the proposed optics using two optical benchtop setups:one with two off-the-shelf FTLs for continuous depth control,and the other with a single Pancharatnam–Berry phase-type FTL for the improved form factor.

关键词： optics crystal phase