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Friction 2024年第9期12卷 2089-2107页

作者： Hao-Ran CHENG ki-hoon shin Hong Seok kiM Department of Mechanical Engineering Graduate School of Seoul National University of Science and TechnologySeoul 01811Republic of Korea Department of Mechanical and Automotive Engineering Seoul National University of Science and TechnologySeoul 01811Republic of Korea

This study focused on producing metal matrix composite(MMC)coatings on Ti–6Al–4V alloy through laser surface alloying using a novel combination of Inconel 625 and SiC precursor *** ratios of alloying powders were examined to evaluate surface properties such as microhardness,wear resistance,and friction coefficient,along with analyzing the phase composition and microstructure of the *** in situ synthesized MMC coatings exhibited the presence ofα-Ti,NiTi,NiTi_(2),and TiC ***,Ti_(5)Si_(3)andα-Ti/Ti_(5)Si_(3)eutectic structures were observed when the SiC content exceeded 20%.In comparison to the titanium substrate,the MMC coating significantly enhanced microhardness by over threefold and reduced wear by 95%.However,it was crucial to carefully select the appropriate combination of alloying powders to avoid a substantial decrease in friction performance and excessive formation of *** a comparative analysis of experimental results,the optimal precursor material composition was identified as 85%Inconel 625 and 15%*** study demonstrated the effective utilization of Inconel 625 and SiC alloying materials to enhance the surface properties of titanium alloys,thereby expanding their application in challenging environments.

关键词： titanium alloy Inconel 625 SiC ceramic laser surface alloying metal matrix composite(MMC)

Novel ternary metals-based telluride electrocatalyst with synergistic effects of high valence non-3d metal and oxophilic Te for pH-universal hydrogen evolution reaction

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Journal of Energy Chemistry 2023年第5期80卷 736-743,I0015页

作者： Seunghwan Jo Wenxiang Liu Yanan Yue ki hoon shin Keon Beom Lee Hyeonggeun Choi Bo Hou Jung Inn Sohn Division of Physics and Semiconductor Science Dongguk UniversitySeoul 04620Republic of Korea School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072HubeiChina School of Physics and Astronomy Cardiff UniversityCardiff CF243AAWalesUK

Electrocatalyst designs based on oxophilic foreign atoms are considered a promising approach for developing efficient pH-universal hydrogen evolution reaction(HER)electrocatalysts by overcoming the sluggish alkaline HER ***,we design ternary transition metals-based nickel telluride(Mo WNi Te)catalysts consisting of high valence non-3d Mo and W metals and oxophilic Te as a first demonstration of non-precious heterogeneous electrocatalysts following the bifunctional *** Mo WNi Te showed excellent HER catalytic performance with overpotentials of 72,125,and 182 mV to reach the current densities of 10,100,and 1000 mA cm^(-2),respectively,and the corresponding Tafel slope of 47,52,and 58 mV dec-1in alkaline media,which is much superior to commercial Pt/***,the HER performance of Mo WNi Te is well maintained up to 3000 h at the current density of 100 mA cm^(-2).It is further demonstrated that the Mo WNi Te exhibits remarkable HER activities with an overpotential of 45 mV(31 mV)and Tafel slope of 60 mV dec-1(34 mV dec-1)at 10 mA cm^(-2)in neutral(acid)*** superior HER performance of Mo WNi Te is attributed to the electronic structure modulation,inducing highly active low valence states by the incorporation of high valence non-3d transition *** is also attributed to the oxophilic effect of Te,accelerating water dissociation kinetics through a bifunctional catalytic mechanism in alkaline *** functional theory calculations further reveal that such synergistic effects lead to reduced free energy for an efficient water dissociation process,resulting in remarkable HER catalytic performances within universal pH environments.

关键词： Telluride catalyst Oxophilic effect High valence non-3d metal Bifunctional mechanism pH-universal hydrogen evolution reaction

Morbidity analysis of left hepatic trisectionectomy for hepatobiliary disease and live donor

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Hepatobiliary & Pancreatic Diseases International 2022年第4期21卷 362-369页

作者： Young-In Yoon Sung-Gyu Lee Deok-Bog Moon shin Hwang ki-Hun kim Hui-Ju kim ki-hoon Choi Division of Hepatobiliary Surgery and Liver Transplantation Department of SurgeryAsan Medical CenterUniversity of Ulsan College of Medicine388-1 Poongnap-dongSongpa-guSeoul 138-736Korea Department of Surgery Gold Coast University HospitalSouthportQLD 4215Australia

Background:Despite remarkable advances in surgical techniques and perioperative management,left hepatic trisectionectomy(LHT)remains a challenging procedure with a somewhat high postoperative morbidity rate compared with less-extensive *** study aimed to analyze the short-and long-term outcomes of LHT and identify factors associated with the postoperative morbidity of this technically demanding surgical ***:The medical records of 53 patients who underwent LHT between June 2005 and October 2019 at a single institution were retrospectively *** independent prognostic factor of postoperative morbidity was analyzed using the logistic regression ***:Hepatocellular carcinoma was the most common indication for surgery(n=21),followed by hilar cholangiocarcinoma(n=14),intrahepatic cholangiocarcinoma(n=10),and other pathologies(including colorectal liver metastasis,hepatolithiasis,gallbladder cancer,living donor,hemangioma,and multilocular biliary cyst;n=8).The rates of postoperative morbidities of Clavien-Dindo grade 3 or higher and 90-day mortality were 39.6% and 1.9%,*** 1-,3-,and 5-year overall survival rates were 81.1%,61.4%,and 44.6%,*** analysis revealed that preoperative jaundice[hazard ratio(HR)=6.15,95%confidence interval(CI):1.57-24.17,P=0.009]and operative time>420 min(HR=4.66,95%CI:1.27–17.17,P=0.021)were independent predictors of postoperative ***:The in-hospital mortality of LHT surgery can be minimalized by a reliable preoperative evaluation of liver function and selection of the dominant anatomic features of right posterior sector,active and appropriate preoperative management for obstructive cholangitis and compensatory hypertrophy of the future remnant posterior sector,and the experience of the surgeon.

关键词： Left hepatic trisectionectomy Major hepatectomy Liver neoplasms Survival rate Morbidity

Hypothyroid effects on astrocytes and microglia in the adult rat hippocampus

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Neural Regeneration Research 2009年第12期4卷 1078-1082页

作者： Choong Hyun Lee Jung hoon Choi In Koo Hwang ki-Yeon Yoo Hyung-Cheul shin Moo-Ho Won Department of Anatomy and Neurobiology and Institute of Neurodegeneration and NeuroregenerationCollege of MedicineHallym University South Korea Institute of Naturat Medicine Hallym University Department ofAnatomy and Cell Biology College of Veterinary Medicine and BK21 Program for Veterinary ScienceSeoul National Unlversity South Korea Institute of Natural Medicine Hallym University Department of Physiology College of MedicineHallym University

BACKGROUND： Thyroid hormones modulate proliferation of astrocytes and microglia depending on maturation stage and localization. Studies have demonstrated that triiodothyronine treatment or thyroidectomy during developmental stages results in morphological alterations and changes in the number of astrocytes and microglia. Little is known about the effects of hypothyroidism on astrocytes and microglia in adults. OBJECTIVE： To investigate the effects of hypothyroidism on morphology and number of astrocytes and microglia in the adult rat hippocampus. DESIGN, TIME AND SETTING： A randomized, controlled, neuroendocrinological, animal study was performed at the College of Medicine, Hallym University, South Korea between May 2008 and April 2009. MATERIALS： Methimazole, rabbit anti-glial fibrillary acidic protein （GFAP） antiserum, and rabbit anti-lba-1 antiserum were purchased from Sigma, USA. Rabbit anti-GFAP polyclonal antibody was provided by Chemicon, USA. Rabbit anti-lba-1 polyclonal antibody was purchased from Wako, Japan. Terminal deoxynucleotidyl transferase dUTP-biotin nick-end-labeling （TUNEL） kit was provided by Roche Molecular Biochemicals, Mannheim, Germany. METHODS： Hypothyroidism was induced in Wistar rats via methimazole administration （0.025%） in drinking water for 5 weeks, starting at 6 months of age. MAIN OUTCOME MEASURES： Following methimazole treatment, hippocampai neuronal death was determined using TUNEL staining. The morphology and number of GFAP and lba-1 immunoreactive cells were detected by immunohistochemistry. Hippocampal GFAP and lba-1 protein levels were detected by Western blot analysis. Serum-free triiodothyronine and thyroxine levels were quantified. RESULTS： TUNEL-positive neurons were not observed in the hippocampus of euthyroid and hypothyroid rats. Compared with the euthyroid rats, the number of GFAP immunoreactive astrocytes was decreased, and serum triiodothyronine and thyroxine levels were significantly decreased. In contrast, the numb

关键词： astrocytes hippocampus hypothyroidism microglia Wistar rats

Fluid flow and heat transfer characteristics of spiral coiled tube: Effects of Reynolds number and curvature ratio

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Journal of Central South University 2012年第2期19卷 471-476页

作者： YOO Geun-jong CHOI hoon-ki DONG Wa-ryong School of Mechatronics Changwon National University

Numerical analysis was performed to investigate flow and heat transfer characteristics in spiral coiled tube heat exchanger. Radius of curvature of the spiral coiled tube was gradually increased as total rotating angle reached 12n. As the varying radius of curvature became a dominant flow parameter, three-dimensional flow analysis was performed to this flow together with different Reynolds numbers while constant wall heat flux condition was set in thermal field. From the analysis, centrifugal force due to curvature effect is found to have significant role in behavior of pressure drop and heat transfer. The centrifugal force enhances pressure drop and heat transfer to have generally higher values in the spiral coiled tube than those in the straight tube. Even then, friction factor and Nusselt number are found to follow the proportionality with square root of the Dean number. Individual effect of flow parameters of Reynolds number and curvature ratio was investigated and effect of Reynolds number is found to be stronger than that of curvature effect.

关键词： spiral coiled tube heat exchanger Reynolds number curvature ratio secondary flow friction factor Nusselt number

Performance Analysis of a Chunk-Based Speech Emotion Recognition Model Using RNN

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Intelligent Automation & Soft Computing 2023年第4期36卷 235-248页

作者： Hyun-Sam shin Jun-ki Hong Division of Software Convergence Hanshin UniversityOsan-si18101Korea Division of AI Software Engineering Pai Chai UniversityDaejeon35345Korea

Recently,artiﬁcial-intelligence-based automatic customer response sys-tem has been widely used instead of customer service ***,it is important for automatic customer service to promptly recognize emotions in a customer’s voice to provide the appropriate service ***,we analyzed the performance of the emotion recognition(ER)accuracy as a function of the simulation time using the proposed chunk-based speech ER(CSER)*** proposed CSER model divides voice signals into 3-s long chunks to efﬁ-ciently recognize characteristically inherent emotions in the customer’s *** evaluated the performance of the ER of voice signal chunks by applying four RNN techniques—long short-term memory(LSTM),bidirectional-LSTM,gated recurrent units(GRU),and bidirectional-GRU—to the proposed CSER model individually to assess its ER accuracy and time efﬁ*** results reveal that GRU shows the best time efﬁciency in recognizing emotions from speech signals in terms of accuracy as a function of simulation time.

关键词： RNN speech emotion recognition attention mechanism time efﬁciency

Aging Analysis Framework of Windows-Based Systems through Differential-Analysis of System Snapshots

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Computers, Materials & Continua 2022年第12期73卷 5091-5102页

作者： Eun-Tae Jang Sung hoon Baek ki-Woong Park SysCore Lab Sejong UniversitySeoul05006Korea Department of Computer System Engineering Jungwon UniversityChungcheongbuk-do28024Korea

When aWindows-based system is used for an exceedingly long time,its performance degrades,and the error occurrence rate tends to *** is generally called system *** investigate the reasons for system aging,various studies have been conducted within the range of the operating system kernel to the user ***,finding an accurate reason for system performance degradation remains challenging research *** this study,system monitoring was conducted by dividing a system into‘before software installation,’‘after software installation,’and‘after software removal.’We confirmed that when a software installed in a system is removed,various system elements,such as storage and memory,are not restored to the level prior to the software ***,we established a hypothesis regarding the performance degradation of a computer system owing to repeated software installation/removal operations,investigated the correlation between system aging and repeated software installation/removal operations,and proposed a system aging analysis framework for analyzing the reason behind system *** the proposed system aging analysis framework,we aim to forcibly age a Windows-based system by repeating the software installation/removal operation by utilizing the system forced aging *** framework identifies the elements affecting system performance through a differential data analysis of the system time-series data extracted by the system performance extraction and system component snapshot ***,the aging analysis framework presented in this study is expected to be effectively utilized as an index for studying system aging.

关键词： System aging virtual machine system analysis

Characteristics of radiation and convection heat transfer in indirect near-infrared-ray heating chamber

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Journal of Central South University 2011年第3期18卷 731-738页

作者： CHOI hoon-ki YOO Geun-jong kiM Churl-hwan School of Mechatronics Changwon National University

Numerical study was performed to evaluate the characteristics of combined heat transfer of radiation, conduction and convection in indirect near infrared ray （N/R） heating chamber. The effects of important design parameters such as the shape of heat absorbing cylinder and heat releasing fin on the pressure drop and heat transfer coefficient were analyzed with different Reynolds numbers. The Reynolds numbers were varied from 103 to 3x106, which was defined based on the hydraulic diameter of the heat absorbing cylinder. Analyses were performed to obtain the inner and outer flow and the temperature distributions in the heat absorbing cylinder and the rates of radiation heat transfer and convection heat transfer. As the Reynolds number increases, the convection heat transfer rate is increased while the radiation heat transfer rate is decreased. The average convection heat transfer rate follows a power rule of the Reynolds number. Addition of three-dimensional heat releasing fin to the outside of the heat absorbing cylinder enhances the convection heat transfer.

关键词： near infrared ray indirect near infrared ray heater absorbing cylinder heat releasing fin radiation heat transfer convection heat transfer Reynolds number

Increased incidence of chemoport-related thrombosis in patients with colorectal cancer receiving bevacizumab: A single-institutional experience

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Chinese Journal of Cancer Research 2018年第4期30卷 460-467页

作者： Jwa hoon kim Jeong Eun kim Yong Sang Hong Sun Young kim Kyu-pyo kim ki Eun Choi Ji hoon shin Tae Won kim Department of Oncology Asan Medical Center University of Ulsan College of Medicine Department of Radiology Asan Medical Center University of Ulsan College of Medicine

Objective： Chemoport-related thrombosis （CRT） is a serious complication that causes morbidities and interruptsadministration of intravenous cancer therapy. We investigated the incidence and risk of CRT in colorectal cancer（CRC） patients treated with bevacizumab （BEV）.Methods： We retrospectively reviewed 1,534 CRC patients who received chemotherapy with or without BEVusing a chemoport between 2014 and ***： The participants had a median age of 58 （18-85） years, and 60.3% were male. All participants werestratified into three groups： adjuvant chemotherapy （AC）（n=670）, palliative chemotherapy （PC） without BEV（n=356）, and PC with BEV （n=508）. The median follow-up was 20.19 （interquartile range, 14.07-27.19） *** occurred in 3.8% of all patients; incidence of symptomatic and asymptomatic CRT was 2.9% and 0.9%,respectively. CRT occurred more in patients with BEV （5.7%） than in patients without BEV （2.9%, P=0.008）. Thecumulative incidence of CRT in patients administered PC with BEV was significantly higher than that in thoseadministered AC （P=0.011） and there was a trend toward increased CRY in patients administered PC with BEVcompared with those administered PC without BEV （P=0.044）. Multivariate analysis found that BEV treatment wasthe only variable that was significandy associated with CRT （hazard ratio, 2.06; 95% confidence interval, 1.24-3.43;P=0.006）.Conclusions： BEV treatment was significandy associated with increased incidence of CRT in CRC patients.

关键词： Bevacizumab central venous catheters thrombosis colorectal neoplasms

Robotic versus laparoscopic distal pancreatectomy for pancreatic ductal adenocarcinoma: A propensity score-matched analysis

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Hepatobiliary & Pancreatic Diseases International 2023年第2期22卷 154-159页

作者： Dakyum shin Jaewoo Kwon Jae hoon Lee Seo Young Park Yejong Park Woohyung Lee ki Byung Song Dae Wook Hwang Song Cheol kim Division of Hepato-Biliary and Pancreatic Surgery Department of SurgeryAsan Medical CenterUniversity of Ulsan College of Medicine88 Olympic-ro 43-gilSongpa-guSeoul 05505Korea Department of Surgery Kangbuk Samsung HospitalSungkyunkwan University School of Medicine29 Saemunan-roJongno-guSeoul 03181Korea Department of Statistics and Data Science Korea National Open University86 Daehak-roJongno-guSeoul 03087Korea

Background: Minimally invasive surgery is becoming increasingly popular in the field of pancreatic surgery. However, there are few studies of robotic distal pancreatectomy(RDP) for pancreatic ductal adenocarcinoma(PDAC). This study aimed to investigate the efficacy and feasibility of RDP for PDAC. Methods: Patients who underwent RDP or laparoscopic distal pancreatectomy(LDP) for PDAC between January 2015 and September 2020 were reviewed. Propensity score matching analyses were performed. Results: Of the 335 patients included in the study, 24 underwent RDP and 311 underwent LDP. A total of 21 RDP patients were matched 1:1 with LDP patients. RDP was associated with longer operative time(209.7 vs. 163.2 min;P = 0.003), lower open conversion rate(0% vs. 4.8%;P < 0.001), higher cost(15 722 vs. 12 699 dollars;P = 0.003), and a higher rate of achievement of an R0 resection margin(90.5% vs. 61.9%;P = 0.042). However, postoperative pancreatic fistula grade B or C showed no significant intergroup difference(9.5% vs. 9.5%). The median disease-free survival(34.5 vs. 17.3 months;P = 0.588) and overall survival(37.7 vs. 21.9 months;P = 0.171) were comparable between the groups. Conclusions: RDP is associated with longer operative time, a higher cost of surgery, and a higher likelihood of achieving R0 margins than LDP.

关键词： Minimally invasive surgery Robotic distal pancreatectomy Laparoscopic distal pancreatectomy Pancreatic ductal adenocarcinoma Propensity score matching