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Journal of Wuhan University of Technology(Materials Science) 2018年第3期33卷 525-532页

作者： Kyung Do joo Do Hoon Kim Gui Yung Chung Department of Chemical Engineering Hong Ik University

Effects of operating parameters in the thermal gradient chemical vapor infiltration of propane such as thermal gradient, diffusion, infiltrations time, and concentration of propane were studied by focusing on the visualizations of the intrinsic effects of these parameters. A uniform deposition in the preform was obtained with a gradually increasing temperature along the gas flow. The uniformity of deposition through the preform got improved with increasing deposition time. Results of numerical modeling estimated the experimental data very well when the pre-exponential factor of the overall rate of carbon deposition from propane reported by Vaidyaraman[1] was multiplied by 4. The average density of a preform increased by about 3 times from 0.38 to 1.15 g/cm3 after 60 hr deposition with a thermal gradient under the conditions of 3% propane in nitrogen and 840 to 900 ℃.

关键词： TG-CVI propane C/C composites uniform deposition mathematical modeling

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

Highly Stable Silicon–Carbon–Nitrogen Composite Anodes from Silsesquiazane for Rechargeable Lithium-Ion Battery

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Journal of Materials Science & Technology 2016年第3期32卷 195-199页

作者： Yong Seok Kim Yong L.joo Young-Je Kwark School of Chemical & Biomolecular Engineering Cornell University Department of Organic Materials and Fiber Engineering Soongsil University

Herein, we developed novel silicon-carbon-nitrogen （SiCN） composites synthesized by pyrolyzing silsesquiazane polymer as an anode material for rechargeable lithium-ion batteries. Among variable pyrolysis temperatures of 700 ℃, 1000 ℃ and 1300 ℃, the SiCN composites prepared at 1000 ℃ showed the highest capacity with outstanding battery cycle life by cyclic voltammetry and electrochemical impedance spectroscopy. Such good battery and electrochemical performances should be attributed to a proper ratio of carbon and nitrogen or oxygen in the SiCN composites. Furthermore, our SiCN electrode possessed better lithium ion conductivity than pure silicon nanoparticles. This work demonstrates that polymer-derived composites are among the promising strategies to achieve highly stable silicon anodes for rechargeable batteries.

关键词： Polymer-derived ceramics Silsesquiazane Lithium ion battery Lithium ion conductivity

Prospective comparison of prophylactic antibiotic use between intravenous moxifloxacin and ceftriaxone for high-risk patients with post-ERCP cholangitis

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Hepatobiliary & Pancreatic Diseases International 2017年第5期16卷 512-518页

作者： Nam Hee Kim Hong joo Kim Ki Bae Bang Department of Internal Medicine Sungkyunkwan University Kangbuk Samsung Hospital Department of Internal Medicine Dankook University Hospital

BACKGROUND: The use of prophylactic antibiotics before endoscopic retrograde cholangiopancreatography(ERCP) is recommended by all major international gastroenterological societies, especially in the presence of an obstructed biliary system. This study compared the occurrence rate of post-procedural complications, including cholangitis and septicemia between prophylactic intravenous moxifloxacin and ceftriaxone in patients with bile duct obstruction scheduled for therapeutic ***: From November 2013 to July 2015, 86 consecutive patients with biliary obstruction with one or more factors predicting benefits of antibiotic prophylaxis prior to ERCP were included in the current randomized open-label non-inferiority trial(Clinical *** identifier NCT02098486). Intravenous moxifloxacin(400 mg/day) or ceftriaxone(2 g/day)were given 90 minutes before ERCP, and were administered for more than 3 days if the patient developed symptoms and signs of cholangitis or septicemia. Recalcitrant cholangitis was defined as persistence of cholangitis for more than 5 days after ERCP or recurrence of cholangitis within 30 days after ***: Recalcitrant cholangitis occurred in 1(2.3%) and 2(4.8%) patients receiving intravenous moxifloxacin and ceftriaxone group, respectively(P=0.612). Septicemia was noted in1(2.3%) and 1(2.4%) patient in intravenous moxifloxacin and ceftriaxone group, respectively(P=1.0). The mean hospital stay was also not significantly different between the moxifloxacin and ceftriaxone groups(8.8±7.2 vs 9.1±9.4 days, P=0.867). Antibiotic resistance of the isolated pathogens by in vitro activity assay was noted in 1(2.3%) and 2(4.8%) patients in the moxifloxacin and ceftriaxone group, respectively(P=0.612). CONCLUSION: Intravenous moxifloxacin is not inferior to intravenous ceftriaxone for the prophylactic treatment of post-ERCP cholangitis and cholangitis-associated morbidity.

关键词： endoscopic retrograde cholangiopancreatography cholangitis moxifloxacin ceftriaxone recalcitrant cholangitis

Fabrication of Piezoelectric Cellulose Paper and Audio Application

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Journal of Bionic Engineering 2009年第1期6卷 18-21页

作者： Jung-Hwan Kim Sungryul Yun joo-Hyung Kim Jaehwan Kim Creative Research Center for EAPap Actuator Department of Mechanical EngineeringINHA University253 Young-Hyun DongNam GuIncheon402-751Republic of Korea

We report the fabrication process of piezoelectric cellulose paper and the enhancement method of its piezoelectric property. Stretching method with different wet-drawing ratios was introduced to increase the piezoelectric property of cellulose paper during regeneration *** is observed that the Young's modulus and the piezoelectric charge constants are very dependent on the drawing ratio and the direction of nanofibrils of piezoelectric *** the enhanced piezoelectric property,we prove that the flexible regenerated piezoelectric cellulose can be applied to the potential acoustic applications such as thin piezoelectric paper speaker.

关键词： piezoelectric speaker piezoelectricity cellulose wet-drawing process

Soleus arthrogenic muscle inhibition following acute lateral ankle sprain correlates with symptoms and ankle disability but not with postural control

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Journal of Sport and Health Science 2024年第4期13卷 559-568,F0003页

作者： Kyung-Min Kim joo-Sung Kim Alan R.Needle Department of Sport Science Sungkyunkwan UniversitySuwon-si 16419Republic of Korea Department of Health and Human Performance Texas State UniversitySan MarcosTX 78666USA Department of Public Health&Exercise Science Appalachian State UniversityBooneNC 28608USA Department of Rehabilitation Science Appalachian State UniversityBooneNC 28608USA

Background:Acute lateral ankle sprains(ALAS)are associated with long-term impairments and instability tied to altered neural *** muscle inhibition(AMI)has been observed in this population;however,relationships with injury-related impairments are unclear,potentially due to the resting,prone position in which AMI is typically *** AMI during bipedal stance may provide a better understanding of this ***:AMI was assessed in 38 young adults(19 ALAS within 72 h of injury:10 males,21.4±2.7 years;19 healthy controls:10 males,21.9±2.2 years;mean±SD)using the Hoffmann reflex(H-reflex)during bipedal *** stimulation was administered to identify the _(max)imal H-reflex(H_(max))and _(max)imal motor response(M_(max))from the soleus,fibularis longus,and tibialis anterior *** primary outcome measure was the H_(max)/M_(max) *** outcomes included acute symptoms(pain and swelling),postural control during bipedal stance,and self-reported ***:No significant group-by-limb interactions were observed for any ***,a significant group main effect was observed in the soleus muscle(F(1,35)=6.82,p=0.013),indicating significantly lower H_(max)/M_(max) ratios following ALAS(0.38±0.20)compared to healthy controls(0.53±0.16).Furthermore,lower H_(max)/M_(max) ratios in the soleus significantly correlated with acute symptoms and self-reported function but not with postural ***:This study supports previous evidence of AMI in patients with ALAS,providing insight into neurophysiologic impacts of musculoskeletal *** results suggest that assessing AMI in a standing position following acute injury may provide valuable insight into how AMI develops and guide potential therapeutic options to curb and offset the formation of joint instability.

关键词： Acute injuries Balance Hoffmann reflex Neural excitability Patient-reported outcomes

Phylogenetic relationship,biogeography,and conservation genetics of endangered Fraxinus chiisanensis(Oleaceae),endemic to South Korea

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Plant Diversity 2022年第2期44卷 170-180页

作者： Changkyun Kim Dong-Kap Kim Hang Sun joo-Hwan Kim Plant Research Division Honam National Institute of Biological ResourcesMokpo 58762Republic of Korea Forest Biodiversity Division Korea National ArboretumPocheon 11186Republic of Korea CAS Key Laboratory for Plant Biodiversity and Biogeography of East Asia Kunming Institute of BotanyChinese Academy of SciencesKunming 650204YunnanPR China Department of Life Science Gachon UniversitySeongnam 13120Republic of Korea

Endemic plants are important for understanding phylogenetic relationships,biogeographical history,and genetic variation because of their restricted distribution and their role in conserving ***,we investigated the phylogenetic relationships of the Korean endemic Fraxinus chiisanensis by reconstructing the molecular phylogeny of Fraxinus based on two nuclear DNA(nrITS and phantastica)and two chloroplast DNA(psbA-trnH and rp132-trnL)*** our fossil-calibrated phylogenetic framework,we also inferred the biogeographical history of *** provide a scientific basis for the conservation of ***,we determined the levels of genetic diversity and genetic differentiation in this *** information from nuclear and chloroplast DNA sequence data,our molecular phylogenetic analyses identified *** as a genetically distinct unit from its sister group,Fraxinus platypoda from *** molecular dating analyses using nuclear and chloroplast DNA data sets show *** diverged from its sister *** in the Early or Middle Miocene and differentiated in the Late Miocene on the Korean *** results suggest that the divergence of *** was associated with the submergence of the East China Sea land bridge and enhanced monsoons in East *** compared to ***,*** exhibits low genetic diversity within populations and high genetic differentiation among *** results help us to understand the evolutionary history of *** and to develop a conservation strategy for this species.

关键词： East China Sea land bridge Endemic species Fraxinus chiisanensis Korean Peninsula Genetic diversity Biogeography

Development of 3D bicontinuous metal-intermetallic composites through subsequent alloying process after liquid metal dealloying

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Journal of Magnesium and Alloys 2023年第11期11卷 4274-4281页

作者： Jee Eun Jang Jihye Seong Soo-Hyun joo Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Department of Materials Science and Engineering Dankook UniversityCheonan 31116Republic of Korea

This study presents a novel process for the fabrication of metal-intermetallic composites with a 3D bicontinuous structure, achieved through a combination of liquid metal dealloying(LMD) and subsequent alloying. Initially, porous Ti structures are produced using the LMD process, followed by immersion in a molten Mg-3Al(wt%) metal. Due to the higher thermodynamic miscibility of Al with Ti compared to Mg, the concentration of Al in the Ti matrix increases as the immersion time increases. This results in a sequential phase transition within the Ti matrix: α-Ti → Ti_(3)Al → Ti Al. The phase transition considerably affects the hardness and strength of the composite material,with the Mg-Ti_(3)Al-Ti Al composite exhibiting a maximum hardness nearly twice as high as that of the conventional Mg-Ti composite. This innovative process holds potential for the development of various bicontinuous metal-intermetallic composites.

关键词： Liquid metal dealloying Subsequent alloying Metal–intermetallic composite 3D bicontinuous structure Hardness

Surface properties of Al-doped ZnO thin film before and after CF_4/Ar plasma etching

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Plasma Science and Technology 2022年第7期24卷 194-200页

作者： Young-Hee joo Gwan-Ha KIM Doo-Seung UM Chang-Il KIM School of Electrical and Electronics Engineering Chung-Ang UniversitySeoul 06974Republic of Korea Department of Semiconductor Materials and Applications Korea PolytechnicSeongnam 13122Republic of Korea Department of Electrical Engineering Sejong UniversitySeoul 05006Republic of Korea

Al-doped ZnO(AZO) is considered as an alternative to transparent conductive oxide *** and achieving a stable surface are important challenges in the development and optimization of dry etching processes, which must be overcome for the application of AZO in various devices. Therefore, in this study, the etch rate and surface properties of an AZO thin film after plasma etching using the adaptive coupled plasma system were investigated. The fastest etch rate was achieved with a CF_(4)/Ar ratio of 50:50 sccm. Regardless of the ratio of CF_(4) to Ar,the transmittance of the film in the visible region exceeded 80%. X-ray photoelectron spectroscopy analysis of the AZO thin film confirmed that metal-F bonding persists on the surface after plasma etching. It was also shown that F eliminates O vacancies. Consequently, the work function and bandgap energy increased as the ratio of CF-4 increased. This study not only provides information on the effect of plasma on AZO thin film, but identifies the cause of changes in the device characteristics during device fabrication.

关键词： Al-doped ZnO plasma etching F-based plasma surface characteristics X-ray photoelectron spectroscopy ultraviolet photoelectron spectroscopy

Implementation of tactical maneuvers with maneuver libraries

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Chinese Journal of Aeronautics 2020年第1期33卷 255-270页

作者： Do hyeon LEE Chang-joo KIM Sung wook HUR Seong han LEE School of Aerospace Information Engineering Konkuk UniversitySeoul 05029Republic of Korea

This study creates and combines the general maneuver libraries for fixed-wing aircraft to implement tactical ***,the generalized maneuver libraries are established by analyzing the characteristics of tactical maneuvers required in *** 7th order polynomial is applied to both the creation of the maneuver libraries and the generation of the trajectories or flight paths for modal *** track the desired trajectory,we design the Attitude Command Attitude Hold(ACAH)system and the Rate Command Rate Hold(RCRH)system using Model Following Controller(MFC).Moreover,the Line-of-Sight(LOS)guidance law is *** particular,the CONDUIT~?is employed to optimize the gains so that the control systems meet the aircraft Handling Qualities(HQ)***,flight simulations are performed for the longitudinal loop,immelmann-turn,and climb-slalom-descent maneuvers to verify that tactical aggressive maneuvers are realizable via the combination of maneuver *** study can contribute to the development of flight techniques for aircraft tactical maneuvers and to the revision of air force operational manuals.

关键词： 7th order polynomial Attitude command attitude hold system Handling qualities Maneuver libraries Rate command rate hold system Tactical maneuvers