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SEQUENCES OF POWERS OF TOEPLITZ OPERATORS ON THE BERGMAN SPACE

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Acta Mathematica Scientia 2021年第3期41卷 657-669页

作者：陈泳 Kei Ji IZUCHI Kou Hei IZUCHI young joo LEE Department of Mathematics Hangzhou Normal UniversityHangzhou 311121China Department of Mathematics Niigata UniversityNiigata 950-2181Japan Department of Mathematics Faculty of EducationYamaguchi UniversityYamaguchi 753-8511Japan Department of Mathematics Chonnam National UniversityGwangju 61186Korea

We consider Toeplitz operators Tu with symbol u on the Bergman space of the unit ball,and then study the convergences and summability for the sequences of powers of Toeplitz *** first charactreize analytic symbolsφfor which the sequence Tφ*kf or Tφkf converges to 0 or∞as k→∞in norm for every nonzero Bergman function ***,we characterize analytic symbolsφfor which the norm of such a sequence is summable or not *** also study the corresponding problems on an infinite direct sum of Bergman spaces as a generalization of our result.

关键词： Bergman space Toeplitz operator

Adaptive Model Predictive Control for Yaw System of Variable-speed Wind Turbines

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Journal of Modern Power Systems and Clean Energy 2021年第1期9卷 219-224页

作者： Dongran Song Qing Chang Songyue Zheng Sheng Yang Jian Yang young Hoon joo the School of Automation Central South Universityand Hunan Provincial Key Laboratory of Power Electronics Equipment and GridChangsha 410083China the School of Energy Science and Engineering Central South UniversityChangsha 410083China the School of IT Information and Control Engineering Kunsan National UniversityKunsan 54150Korea

Due to varying characteristics of the wind condition, the performance of the wind turbines can be optimized by adapting the parameters of the control system. In this letter, an adaptive technique is proposed for the novel model predictive control(MPC) for the yaw system of the wind turbines. The control horizon is adapted to the one with the best predictive performance among multiple control horizons. The adaptive MPC is demonstrated by simulations using real wind data, and its performance is compared with the baseline MPC at fixed control horizon. Results show that the adaptive MPC provides better comprehensive performance than the baseline ones at different preview time of wind directions. Therefore, the proposed adaptive technique is potentially useful for the wind turbines in the future.

关键词： Wind turbine yaw system wind direction adaptive model predictive control

Effect of robot-assisted gait training on the biomechanical properties of burn scars:a single-blind,randomized controlled trial

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Burns & Trauma 2022年第1期10卷 191-199页

作者： Yoon Soo Cho So young joo Cheong Hoon Seo Department of Rehabilitation Medicine Hangang Sacred Heart HospitalCollege of MedicineHallym UniversitySeoul 07247Republic of Korea

Background:Robot-assisted gait training(RAGT)is more effective in the range of motion(ROM)and isometric strength in patients with burns than conventional ***,concerns have been raised about whether RAGT might negatively affect the scars of patients with ***,we investigated the effects of RAGT-induced mechanical load on the biomechanical properties of burn ***:This was a single-blind,randomized clinical trial conducted on inpatients admitted to the Department of Rehabilitation Medicine between September 2020 and August *** was conducted for 30 min per day,five days a week for 12 weeks and the control group received conventional gait training for 12 *** pre-training ROM of lower extremity joints was evaluated and the levels of melanin,erythema,trans-epidermal water loss,scar distensibility and elasticity were assessed before training and at 4 and 12 weeks after ***,19 patients in the gait assistance robot(GAR)group and 20 patients in the control group completed the 12-week trial and all ***:There were no significant differences in the epidemiologic characteristics,pre-training ROM of joints and pre-training biomechanical properties of the burn scar between the groups(p>0.05 for all).None of the patients experienced skin abrasion around the burn scar where the fastening belts were applied or musculoskeletal or cardiovascular adverse events during the *** thickness significantly increased in both groups(p=0.037 and p=0.019)and scar distensibility significantly decreased in the control group(p=0.011)during the *** was significantly decreased in the GAR group during the training(p=0.038).The GAR and control groups showed significant difference in the change in the values of hysteresis between pre-training and 12 weeks after training(p=0.441 and p=0.049).Conclusions:RAGT significantly decreased hysteresis in hypertrophic burn scars and did not cause a significant decrease

关键词： Robot-assisted gait training Burn Scar biomechanical properties Hysteresis Burn rehabilitation

Etching characteristics and surface modification of InGaSnO thin films under Cl_(2)/Ar plasma

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Plasma Science and Technology 2023年第10期25卷 91-96页

作者： young-Hee joo Jae-Won CHOI Bo HOU Hyuck-In KWON Doo-Seung UM Chang-Il KIM Department of Electronic and Electrical Engineering Chung-Ang UniversitySeoul 06974Republic of Korea Department of Firearms and Optics Daeduk UniversityDaejeon 34111Republic of Korea School of Physics and Astronomy Cardiff UniversityCardiff CF243AAUnited Kingdom Department of Electrical Engineering Sejong UniversitySeoul 05006Republic of Korea

Indium gallium tin oxide(IGTO)thin films have the potential for high mobility and lowtemperature processing,which makes them suitable for applications such as display backplanes and high-voltage switching ***,very few studies have investigated the plasmaetching characteristics of IGTO and changes in its properties after *** this study,the etching characteristics of IGTO were investigated using Cl_(2)/Ar plasma,and changes in surface properties were *** showed that the etch rate increased with an increase in the proportion of Cl_(2),with the highest etch rate observed at 69 nm min^(-1)in pure Cl_(2)plasma with a gas flow rate of 100 ***,increased radio-frequency power caused a rise in the etch rate,while a process pressure of 15 m Torr was *** primary etching mechanism for IGTO thin films under Cl_(2)plasma was a chemical reaction,and an increased work function indicated the occurrence of defects on the *** addition,the etching process reduced the surface roughness of Cl_(2)-containing plasma,whereas the etching process in pure Ar plasma increased surface *** study contributes to a better understanding of the plasmaetching characteristics of IGTO and changes in its properties after etching,providing valuable insights for IGTO-based applications.

关键词： InGaSnO Cl2-based plasma etching mechanism surface modification plasma etching

Stable immobilization of lithium polysulfides using three-dimensional ordered mesoporous Mn2O3 as the host material in lithium-sulfur batteries

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Carbon Energy 2024年第6期6卷 99-112页

作者： Sung joon Park Yun Jeong Choi Hyun-seung Kim Min joo Hong Hongjun Chang Janghyuk Moon young-Jun Kim Junyoung Mun Ki Jae Kim Department of Energy Science Sungkyunkwan UniversitySuwonGyeonggi-doRepublic of Korea Department of Energy Engineering Konkuk UniversitySeoulRepublic of Korea Advanced Batteries Research Center Korea Electronic Technology InstituteSeongnamRepublic of Korea Department of Future Energy Engineering Sungkyunkwan UniversitySuwonRepublic of Korea Department of Energy Systems Engineering Chung-Ang UniversitySeoulRepublic of Korea SKKU Advanced Institute of Nanotechnology Sungkyunkwan UniversitySuwonGyeonggi-doRepublic of Korea SKKU Institute of Energy Science and Technology(SIEST) Sungkyunkwan UniversitySuwonRepublic of Korea School of Advanced Materials Science and Engineering Sungkyunkwan UniversitySuwonRepublic of Korea

Lithium-sulfur batteries(LSBs)have drawn significant attention owing to their high theoretical discharge capacity and energy ***,the dissolution of long-chain polysulfides into the electrolyte during the charge and discharge process(“shuttle effect”)results in fast capacity fading and inferior electrochemical *** this study,Mn_(2)O_(3)with an ordered mesoporous structure(OM-Mn_(2)O_(3))was designed as a cathode host for LSBs via KIT-6 hard templating,to effectively inhibit the polysulfide shuttle ***-Mn_(2)O_(3)offers numerous pores to confine sulfur and tightly anchor the dissolved polysulfides through the combined effects of strong polar-polar interactions,polysulfides,and sulfur chain *** OM-Mn_(2)O_(3)/S composite electrode delivered a discharge capacity of 561 mAh g-1 after 250 cycles at 0.5 C owing to the excellent performance of OM-Mn_(2)O_(3).Furthermore,it retained a discharge capacity of 628mA h g-1 even at a rate of 2 C,which was significantly higher than that of a pristine sulfur electrode(206mA h g-1).These findings provide a prospective strategy for designing cathode materials for high-performance LSBs.

关键词： host material lithium-sulfur battery ordered mesoporous structure shuttle effect transition-metal oxides

Annual Energy Production Estimation for Variable-speed Wind Turbine at High-altitude Site

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Journal of Modern Power Systems and Clean Energy 2021年第3期9卷 684-687页

作者： Dongran Song Songyue Zheng Sheng Yang Jian Yang Mi Dong Mei Su young Hoon joo the School of Automation Central South UniversityChangsha 410083China the School of Energy Science and Engineering Central South UniversityChangsha 410083China the School of IT Information and Control Engineering Kunsan National UniversityKunsan 573701Korea

This letter presents a systematic approach to estimate the annual energy production(AEP) of variable-speed wind turbines erected at high-altitude sites. Compared with the existing empirical-model based approaches, the proposed approach models the influence of the air density on the power production while employing the theoretical power curve. Consequently, the proposed approach provides a precise estimation of AEP, which can serve as a foundation of the optimum turbinesite matching design at different-altitude sites.

关键词： Variable-speed wind turbine annual energy production high-altitude site turbine-site matching

Effects of TiN film coating on electrochemical behaviors of nanotube formed Ti-xHf alloys

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中国有色金属学会会刊：英文版 2009年第4期19卷 857-861页

作者： Kang LEE Won-Gi KIM joo-young CHO Sang-Won EUN Han-Cheol CHOE Department of Dental Materials & Research Center of Nano-Interface Activation for Biomaterials College of DentistryChosun University Department of Applied Advanced Materials Korea Polytechnic Ⅴ Colleges

Ti-xHf(x=10%,20%,30% and 40%,mass fraction) alloys were prepared by arc melting,and the microstructure was controlled for 24 h at 1 000 ℃ in argon *** formation of nanotube was conducted by anodizing on Ti-Hf alloys in 1.0 mol/L H3PO4 electrolytes with small amounts of NaF at room *** then TiN coatings were coated by DC-sputtering on the anodized *** and nanotube morphology of the alloys were examined by field emission scanning electron microscopy(FE-SEM) and X-ray diffractometry(XRD).The corrosion properties of the specimens were examined through potentiodynamic test(potential range from -1 500 to 2 000 mV) in 0.9 % NaCl solution by *** microstructure shows the acicular phase and α' phase with Hf *** amorphous oxide surface is transformed to crystalline anatase *** coated nanotube surface has a good corrosion resistance.

关键词：氮化钛涂层合金制备纳米管电化学行为薄膜包衣 0.9%NaCl溶液扫描电子显微镜微观结构

Usefulness of magnifying endoscopy for iodine-unstained lesions in a high-risk esophageal cancer population

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World Journal of Gastroenterology 2010年第37期16卷 4709-4715页

作者： Ik Seong Choi Jae young Jang Won young Cho Tae Hee Lee Hyun Gun Kim Bo young Lee Soung Won Jeong joo young Cho joon Seong Lee So young Jin Institute for Digestive Research SoonChunHyang University College of Medicine

AIM: To investigate the usefulness of magnified observations of iodine-unstained esophageal lesions in the histological diagnosis of esophageal mucosa abnormalities, in high-risk esophageal cancer groups. METHODS: The subjects included 38 patients who had at least one of the four criteria known to be highrisk factors for esophageal cancer. Following endoscopic observation, magnified observations were performed on iodine-unstained lesions of the esophagus. The total number of lesions was 43. These lesions were classified as type A (clear papilla), type B (fused papilla), and type C (non-visible papilla) according to the findings. Tissue biopsy was then carried out. Finally the histological findings were graded in terms of histological factors, and their relationships were compared. RESULTS: Of the 43 lesions, 11 were type A, 17 were type B, and 15 were type C under magnifying endoscopy. Histological findings such as inflammatory cell infiltration and basal cell hyperplasia were significantly increased in type B and type C lesions compared with type A lesions (P < 0.05). Low-grade esophageal dysplasia was apparent in 1 (9%) of 11 type A lesions, in 3 (18%) of 17 type B lesions, and in 6 (40%) of 15 type C lesions, with the highest rate in type C. CONCLUSION: Magnified observations of the esophagus, classified by papillary aspects using magnifying endoscopy of iodine-unstained lesions in high-risk esophageal cancer groups, are considered useful in estimating dysplasia and inflammation of esophageal mucosa.

关键词： Esophageal cancer Iodine Magnifying endoscopy

Effects of Hybrid Voltages on Oxide Formation on 6061 Al-alloys During Plasma Electrolytic Oxidation

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Chinese Journal of Aeronautics 2009年第5期22卷 564-568页

作者： Kai Wang Bon Heun Koo Chan Gyu Lee young joo Kim Sunghun Lee Eungsun Byon School of Nano & Advanced Materials Engineering Changwon National University Changwon 641-773 Korea Surface Technology Research Center Korea Institute of Materials Science Changwon 641-010 Korea

Plasma electrolytic oxidation （PEO） is carried out on 6061 Al-alloys in a weak alkaline electrolyte containing NaOH, Na2SiO3 and NaCl. Centered on the correlation of composition and structure, analyses by means of X-ray diffration （XRD）, scanning electron microscope （SEM） and energy dispersive spectrometry （EDS） are conducted on the specimens, which have been PEO-treated under hybrid voltages of different direct current （DC） values （140-280 V） with constant alternate current （AC） amplitude （200 V）. Attention is paid to the composition, properties and growth mechanism of oxide layers formed with hybrid voltages. Moreover, the main effects of DC value are discussed. Ceramic layers with a double-layer structure which combines hard outer and soft inner layers are found to be consist of α-Al2O3,γ-Al2O3 and mullite. With the DC values increasing, the growth of the ceramic layers tends to have increasingly obvious three-stage feature.

关键词： plasma electrolytic oxidation oxide layer aluminum alloys alkaline electrolyte hybrid voltages