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Cycloaddition of CO_2 with epoxides by using an amino-acid-based Cu(Ⅱ)–tryptophan MOF catalyst

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Chinese Journal of Catalysis 2018年第1期39卷 63-70页

作者： Gyeong Seon Jeong Amal Cherian Kathalikkattil Robin Babu Yongchul Greg Chung dae won park Division of Chemical and Biomolecular Engineering Pusan National University Busan 609‐735 Korea School of Chemistry University of Dublin Trinity College Dublin 2 Ireland

Metal organic frameworks(MOFs)constructed from natural/biological units(amino acids)are prospective candidates as catalysts in CO2chemistry owing to their natural origin and high abundance of Lewis acid/base sites and functional ***,we report the catalytic efficiency of an amino‐acid‐based Cu‐containing MOF,denoted as CuTrp(Trp=L‐tryptophan).The CuTrp catalyst was synthesized by direct mixing at room temperature using methanol as a solvent-a synthetic route with notable energy *** catalyst was characterized using various physicochemical techniques,including XRD,FT‐IR,TGA,XPS,ICP‐OES,FE‐SEM,and BET *** catalytic activity of CuTrp was assessed in the synthesis of cyclic carbonates from epoxides and *** CuTrp operated in synergy with the co‐catalyst tetrabutylammonium bromide under solvent‐free *** reaction parameters were studied to identify the optimal reaction conditions and a reaction mechanism was proposed based on experimental evidence and previous density functional theory *** CuTrp also exhibited satisfactory stability in water and could be reused more than three times without any significant loss of activity.?2018,Dalian Institute of Chemical Physics,Chinese Academy of *** by Elsevier *** rights reserved.

关键词： Metal organic frameworks Amino acid Copper tryptophan complex Direct mixing Carbon dioxide Cyclic carbonate

Development of a Lightning Warning System

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Journal of Energy and Power Engineering 2012年第2期6卷 287-292页

作者： Gyung-Suk Kil dae-won park Kwang-Seok Jung Chang-Hwan Ahn Division of Electrical and Electronics Engineering National Korea Maritime University Busan 606-791 Korea Department of Digital Electronics ＆ Information Inha Technical College Incheon 402-752 Korea

A lightning warning system （LWS） which can predict the possibility of lightning strike and the position of lightning discharge was developed. The LWS uses the electric field intensity at the ground as a parameter to warn the possibility of lightning strikes. A planar shutter type electric field mill （EFM） with a rotating vane is studied to measure the electric field. From a calibration experiment, the sensitivity of the EFM was adjusted to 0.15 V/kV/m, and this covers the ranges from 200 V/m to 20 kV/m. Magnetic field waveform is detected by a crossed loop coil and an integral amplifier. Frequency bandwidth of the circuit ranges from 5 kHz to 1.2 MHz. The polarity of lightning discharges is discriminated by electric field component. After fixing the polarity, we can calculate the direction and distance of lightning discharge by the peak and the zero cross time of the detected magnetic field waveform.

关键词： Lightning warning system (LWS) electric field mill (EFM) thundercloud lightning discharge electromagnetic field loop coil.

Effects of deforestation on microbial diversity in a Siberian larch(Larix sibirica) stand in Mongolia

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Journal of Forestry Research 2019年第5期30卷 1885-1893页

作者： Jun won Kang Yeong dae park Division of Forest Tree Improvement National Institute of Forest ScienceSuwonGyeonggi 16631Republic of Korea Department of Forest Resources Daegu UniversityGyeongbuk 38453Republic of Korea

For evaluating microbial community changes in a Siberian larch stand disturbed by forest fire or clearcutting,357 clones were randomly selected and sequenced using a culture-independent approach and 16S rRNA sequencing to characterize the bacterial composition and diversity from the different disturbed Siberian larch ***,the burned larch stand had an increase in the relative amounts of b-proteobacteria and Firmicutes and a decrease in Acidobacteria,while Gemmatimonadetes increased Verrucomicrobia decreased in the harvested larch *** diversity and richness were higher in the undisturbed larch stand than the disturbed(burned or clear-cut)larch stands,and the influence of clear-cutting was more negative than that of the forest *** study indicates that evaluating the microbial diversity of undisturbed,burned,and clear-cutting Siberian larch stands provides information about the impact of forest disturbances on soil microbial communities,which may be helpful for understanding and evaluating soil health and devising reafforestation strategies for larch.

关键词： Forest fire Forest health Harvest Microbial diversity Reafforestation Siberian Larch(Larix sibirica) Soil microbiome

Flexible and disposable paper-based gas sensor using reduced graphene oxide/chitosan composite

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Journal of Materials Science & Technology 2022年第6期101卷 165-172页

作者： Hyunjun park Woong Kim Sang won Lee Joohyung park Gyudo Lee dae Sung Yoon wonseok Lee Jinsung park Department of Control and Instrumentation Engineering Korea UniversitySejong 30019Republic of Korea School of Biomedical Engineering Korea UniversitySeoul 02841Republic of Korea Department of Biotechnology and Bioinformatics Korea UniversitySejong 30019Republic of Korea Department of Electrical Engineering Korea National University of TransportationChungju 27469Republic of Korea

Nitrogen dioxide(NO_(2))is a representative toxicant in air pollution that mostly arises from the exhaust gas released by *** is related to various respiratory diseases such as pneumonia and sudden infant death ***,because the toxicity of nitrogen dioxide is high in overpopulated areas(i.e.,a capital or metropolis),the development of simple,practical,and facile sensors is highly *** work presents a flexible and disposable paper-based NO_(2)sensor based on a reduced graphene oxide/chitosan(r GO/CS)*** synthesized r GO/CS composite can be easily flexed and deformed into various shapes,which are attributed to chitosan molecules that function as a dispersion and reduction agent and support *** addition,this composite can be attached to paper owing to its adhesive property;hence it can be utilized in versatile applications in a disposable *** analyzing the conductive change of the r GO/CS composite when it reacts with NO_(2),we can detect nitrogen dioxide in a concentration range of 0–100 ppm with a detection limit of 1 ***,we performed NO_(2)detection in the exhaust gas released by automobiles using the r GO/CS composite for practical *** results indicated that the r GO/CS composite has the potential to be used in feasible gas sensing as a facile and disposable sensor under various conditions.

关键词： Reduced graphene oxide Chitosan Composite material Nitrogen dioxide Paper-based gas sensor Flexible and disposable sensor

Self-Assembled Wire Arrays and ITO Contacts for Silicon Nanowire Solar Cell Applications

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Chinese Physics Letters 2011年第3期28卷 132-135页

作者： YANG Cheng ZHANG Gang LEE dae-Young LI Hua-Min LIM Young-dae YOO won Jong park Young-Jun KIM Jong-Min Sungkyunkwan University SKKU Advanced Institute of Nano Technology300 Cheoncheon-dongJangan-guSuwon 440-746Korea Samsung Electronics Co.Ltd. San 14-1 Nongseo-dongGiheung-guYongin 446-712Korea

Self-assembly of silicon nanowire(SiNW)arrays is studied using SF_(6)/0_(2)plasma *** self-assembly method can be applied to single-and poly-crystalline Si *** conditions can control the length and diameter of the SiNW *** reflectance of the wire arrays over the wavelength range 200-1100nm is *** conducting transparent indium-tin-oxide(ITO)electrode can be fully coated on the self-assembled SiNW arrays by *** ITO-coated SiNW solar cells show the same low surface light reflectance and a higher carrier collection efficiency than SiNW solar cells without ITO *** efficiency enhancement of around 3 times for ITO coated SiNW solar cells is demonstrated via experiments.

关键词： reflectance Solar transparent

Exploration of cobalt selenite-carbon composite porous nanofibers as anode for sodium-ion batteries and unveiling their conversion reaction mechanism

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Journal of Materials Science & Technology 2021年第30期89卷 24-35页

作者： Jin-Sung park Gi dae park Yun Chan Kang Department of Materials Science and Engineering Korea UniversityAnam-DongSeongbuk-GuSeoul136-713Republic of Korea

Efforts have been made to develop a promising anode material with a novel composition for sodiumion batteries(SIBs).In this study,the sodium-ion storage mechanism of transition metal selenite that comprises transition metal cation coupled with two anions is *** cobalt selenite(CoSeO_(3))-carbon composite nanofibers containing numerous pores are synthesized via electrospinning *** heat treatment of the electrospun nanofibers containing selenium,CoSe_(2)nanoclusters are *** the subsequent oxidation,CoSe_(2)transformed into amorphous CoSeO_(3)and some part of carbon was oxidized into CO_(2),leaving the pores inside the *** unveil the electrochemical reaction mechanism,analytical methods including cyclic voltammetry,ex-situ X-ray photoelectron spectroscopy,ex-situ transmission electron microscopy,and in-situ electrochemical impedance spectroscopy techniques were *** on the analyses,the following conversion reaction from the second cycle onward is suggested:CoO+xSeO_(2)+(1-x)Se+4(x+1)Na^(+)+4(x+1)e~-?Co+(2x+1)Na_(2)O+Na_(2)***,the electrochemical properties of porous CoSeO_(3)-carbon composite nanofibers are analyzed in *** anode material exhibited stable cycle stability up to 200 cycles at 0.5 A g^(-1)and high rate performance up to 5 A g^(-1).

关键词： Anode materials Sodium-ion batteries Conversion reaction Metal selenite Electrospinning

Rational design and synthesis of hierarchically structured SnO2 microspheres assembled from hollow porous nanoplates as superior anode materials for lithium-ion batteries

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Nano Research 2018年第3期11卷 1301-1312页

作者： Gi dae park Yun Chan Kang Department of Materials Science and Engineering Korea University Anam-Dong Seongbuk-Gu Seoul 136-713 Republic of Korea

Herein, hierarchically structured SnO2 microspheres are designed and synthesized as an efficient anode material for lithium-ion batteries using hollow SnO2 nanoplates. Three-dimensionally ordered macroporous （3-DOM） SnOx-C microspheres synthesized by spray pyrolysis are transformed into hierarchically structured SnO2 microspheres by a two-step post-treatment process. Sulfidation produces hierarchically structured SnS-SnS2-C microspheres comprising tin sulfide nanoplate and carbon building blocks. A subsequent oxidation process produces SnO2 microspheres from hollow SnO2 nanoplate building blocks, which are formed by Kirkendall diffusion. The discharge capacity of the hierarchically structured SnO2 microspheres at a current density of 5 Ag^-1 for the 600th cycle is 404 mA·h·g^-1. The hierarchically structured SnO2 microspheres have reversible discharge capacities of 609 and 158 mA·h·g^-1 at current densities of 0.5 and 30 Ag^-1, respectively. The ultrafine nanosheets contain empty voids that allow excellent lithium-ion storage performance, even at high current densities.

关键词： Kirkendall diffusion nanoplate tin oxide lithium-ion batter spray pyrolysis

Risk factors of electrocoagulation syndrome after esophageal endoscopic submucosal dissection

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World Journal of Gastroenterology 2018年第10期24卷 1144-1151页

作者： dae won Ma Young Hoon Youn Da Hyun Jung Jae Jun park Jie-Hyun Kim Hyojin park Department of Internal Medicine Gangnam Severance Hospital Yonsei University College of Medicine

AIM To investigate post endoscopic submucosal dissection electrocoagulation syndrome(PEECS) of the *** We analyzed 55 consecutive cases with esophageal endoscopic submucosal dissection for superficial esophageal squamous neoplasms at a tertiary referral hospital in South Korea. Esophageal PEECS was defined as "mild" meeting one of the following criteria without any obvious perforation: fever(≥ 37.8 ℃), leukocytosis(> 10800 cells/μl), or regional chest pain more than 5/10 points as rated on a numeric pain intensity scale. The grade of PEECS was determined as "severe" when meet two or more of above *** We included 51 cases without obvious complications in the analysis. The incidence of mild and severe esophageal PEECS was 47.1% and 17.6%, respectively. Risk factor analysis revealed that resected area, procedure time, and muscle layer exposure were significantly associated with PEECS. In multivariate analysis, a resected area larger than 6.0 cm^2(OR = 4.995, 95%CI: 1.110-22.489, P = 0.036) and muscle layer exposure(OR = 5.661, 95%CI: 1.422-22.534, P = 0.014) were independent predictors of esophageal PEECS. All patients with PEECS had favorable outcomes with conservative management approaches, such as intravenous hydration or *** Clinicians should consider the possibility of esophageal PEECS when the resected area exceeds 6.0 cm^2 or when the muscle layer exposure is noted.

关键词： Electrocoagulation Endoscopic submucosal dissection Esophageal neoplasm Syndrome

Growth and Magnetic Properties of Sol-Gel Derived Co-Doped ZnO Thin Film

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Journal of Rare Earths 2006年第z1期24卷 59-63页

作者： Young Sung Kim Ki Chul Kim won Pil Tae dae Ho Yoon Tae Seok park Su Jeong Suh Advanced Material Process of Information Technology Sungkyunkwan University Suwon 440-746 Korea Cambridge-ETRI Joint R&D Centre Electronics and Telecommunications Research Institute Daejeon 305-350 Korea Ulsan Industry Promotion Techno Park Ulsan 683-804 Korea Advanced Material Process of Information Technology Sungkyunkwan University Suwon 440-746 Korea Advanced Material Process of Information Technology Sungkyunkwan University Suwon 440-746 Korea Advanced Material Process of Information Technology Sungkyunkwan University Suwon 440-746 Korea

Zn1-xCoxO films were grown on glass by sol-gel spin coating process. A homogeneous and stable Zn1-xCoxO sol was prepared by dissolving zinc acetate dihydrate, cobalt acetate tetrahydrate and aluminium chloride hexahydrate as solutes in solution of isopropanol and monoethanolamine. The films were postheated and vacuum annealed, and investigated for c-axis preferred orientation and electromagnetic properties. Zn1-xCoxO films with different Co concentrations were oriented well along the c-axis, especially the Zn1-xCoxO film with 10% Co(atom fraction) was highly c-axis oriented. The transmittance spectra show that Zn1-xCoxO films occur d-d transition and sp-d exchange interaction between Co2+ ions. The electrical resistivity of the films at 10% Co had the lowest value because the crystallite size became largest and the crystallinity of the c-axis was improved. X-ray photoelectron spectroscopy and alternating gradient magnetometer analyses indicated that no Co metal cluster was formed, and the ferromagnetism at room temperature appeared. The characteristics of the electrical resistivity and room temperature ferromagnetism of sol-gel derived Zn1-xCoxO films suggest a potential application of dilute magnetic semiconductor devices.

关键词： sol-gel Zn1-xCoxO thin film dilute magnetic semiconductor (DMS)