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Preparation of SnO Nanosheets and SnO_2 Fine Powders by Hydrazine Method

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稀有金属材料与工程 2006年第A3期35卷 43-46页

作者： Kang-Min kim jong-Heun Lee Department of Materials Science & Engineering Korea UniversitySeoul 136-713Korea

SnO nanosheets and SnO_2 nanopowder were prepared by hydrazine (N_2H_4)-based chemical routes and their gas sensing characteristics were investigated.A SnCl_2-Hydrazine complex (Sn[ N_2H_4)_x]·yH_2O) was formed by a reaction between a SnCl_2 aqueous solution and N_2H_4·H_*** this complex was heat-treated at 450℃,SnO_2 nanopowders were prepared by the decomposition of the *** sensor fabricated from the SnO_2 nano powders showed a good recovery,fast response and high sensitivity for CO 50μg/g (R_a/R_g=1.87),C_2H_5OH 100μg/g (R_a/R_g=4.80),and acetone 100μg/g (R_a/R_g=1.50).SnO nano- sheets could be prepared when a NaOH solution was added to the solution containing the ***_2 nano sheets prepared by the oxidation of SnO nanosheets at 700℃in air atmosphere also showed a good sensitivity R_a/R_g=1.79) for CO 50μg/g at 400℃.The hydrazine method provided an effective tool to controlling the morphology and oxidation state of the tin oxide powders.

关键词： SnO2 SnO hydrazine method gas sensor nanosheets nanopowders

Electrochemical characteristics of Al-Mg and Al-Mg-Si alloy in sea water

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中国有色金属学会会刊：英文版 2012年第S3期22卷 881-886页

作者： Seong-jong kim Seung-jun LEE Jae-yong JEONG Kyu-hwan kim Division of Marine Engineering Mokpo Maritime University

Among Al alloys,particularly 5000 series Al Mg and 6000 series Al Mg Si often used as marine materials have excellent corrosion resistance,low melting point,and thereby showing recycling availability when compared to other *** experiments were conducted to select the most suitable material for marine *** electrochemical experiments were conducted in natural *** corrosion test was performed in many methods such as anodic/cathodic polarization and Tafel analysis using multi-channel potentio/galvanostat WMPG *** results,anodic and cathodic polarization behaviors indicate the characteristics of passive state and concentration polarization by reduction reaction in dissolved oxygen,which shows excellent electrochemical *** analysis results show no significant difference but 5052-O alloy of various alloy materials indicates the lowest corrosion current ***,5052-O Al alloy presents most anti-corrosion material in marine environment.

关键词： Al alloy ship electrochemical characteristics corrosion

“Standby” EMT and “immune cell trapping” structure as novel mechanisms for limiting neuronal damage after CNS injury

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Neural Regeneration Research 2014年第23期9卷 2032-2035页

作者： jong-Ho Cha Kyu-Won kim SNU-Harvard Neuro Vascular Protection Research Center College of Pharmacy Seoul National University Department of Molecular Medicine and Biopharmaceutical Sciences Graduate School of Convergence Science and Technology and College of Medicine or College of PharmacySeoul National University

The central nervous system （CNS） contains the two most important organs, the brain and spinal cord, for the orchestration of the mental and physical activities of life. Because of its importance, the human body has evolved barrier systems to protect CNS tissue from the external environment. This barrier is a membrane composed of tightly apposed cells and is selectively permeable to specific molecules by way of membrane transporters.

关键词： EMT and immune cell trapping Standby CNS structure as novel mechanisms for limiting neuronal damage after CNS injury cell

Material Characterization of Ni Base Alloy for Very High Temperature Reactor

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Journal of Materials Science & Technology 2013年第12期29卷 1184-1190页

作者： Dong-Jin kim Gyeong-Geun Lee Dae jong kim Su Jin Jeong Nuclear Materials Division Korea Atomic Energy Research Institute

The generation of highly efficient electricity and the production of massive hydrogen are possible using a very high temperature reactor （VHTR） among generation IV nuclear power plants. The structural material for an intermediate heat exchanger （IHX） among numerous components should be endurable at high temperature of up to 950 °C during long-term operation. Impurities inevitably introduced in helium as a coolant facilitate the material degradation by corrosion at high temperature. In the present work, the surface reactions available under controlled impure helium at 950 °C were investigated based on the thermodynamics and the corrosion tests were performed in a temperature range of 850-950 °C during 10-250 h for commercial Alloy 617 as a candidate material for an IHX. Moreover, the mechanical property and microstructure for nickel-based alloys fabricated in laboratory were evaluated as a function of the processing parameters such as hot rolling and heat treatment conditions. From the reaction rate constant obtained from an impure helium control system for a material evaluation, it was predicted that the outer oxide layer thickness, internal oxide depth, and carbide- depleted zone depth reach about 116, 600 and 1000 μm, respectively when Alloy 617 is exposed to an impure helium environment at 950 ~C for 20 years. For Ni-Cr-Co-Mo alloy, subsequent annealing and a combination of cold working and subsequent annealing following solution annealing caused increases in the grain boundary carbide coverage and size. The angular distribution of the grain boundary as well as the carbide distribution was also changed leading to a consequent improvement of the mechanical property at 950 °C in air.

关键词： Nickel base alloy Intermediate heat exchanger High temperature reactor Corrosion Mechanical property

Robust and Reusable Fuzzy Extractors from Non-Uniform Learning with Errors Problem

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Computers, Materials & Continua 2023年第1期74卷 1985-2003页

作者： Joo Woo jonghyun kim jong Hwan Park Graduate School of Information Security Korea UniversitySeoul02841Korea Department of Computer Science Sangmyung UniversitySeoul03016Korea

Afuzzy extractor can extract an almost uniformrandom string from a noisy source with enough entropy such as biometric *** reproduce an identical key from repeated readings of biometric data,the fuzzy extractor generates a helper data and a random string from biometric data and uses the helper data to reproduce the random string from the second *** 2013,Fuller et *** a computational fuzzy extractor based on the learning with errors *** construction,however,can tolerate a sub-linear fraction of errors and has an inefficient decoding algorithm,which causes the reproducing time to increase *** 2016,Canetti et *** a fuzzy extractor with inputs from low-entropy distributions based on a strong primitive,which is called digital ***,their construction necessitates an excessive amount of storage space for the helper data,which is stored in authentication *** on these observations,we propose a new efficient computational fuzzy extractorwith small size of helper *** scheme supports reusability and robustness,which are security notions that must be satisfied in order to use a fuzzy extractor as a secure authentication method in real ***,it conceals no information about the biometric data and thanks to the new decoding algorithm can tolerate linear *** on the non-uniform learning with errors problem,we present a formal security proof for the proposed fuzzy ***,we analyze the performance of our fuzzy extractor scheme and provide parameter sets that meet the security *** a result of our implementation and analysis,we show that our scheme outperforms previous fuzzy extractor schemes in terms of the efficiency of the generation and reproduction algorithms,as well as the size of helper data.

关键词： Fuzzy extractor reusability robustness biometric authentication non-uniform learning with errors

NIR-Ⅱ thiopyrylium dyads guided photodynamic inactivation of coronavirus

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Science China Chemistry 2023年第7期66卷 1877-1878页

作者： Yunjie Xu Changyu Yoon jong Seung kim Department of Chemistry Korea UniversitySeoul 02841Korea

COVID-19,a highly contagious respiratory infection caused by the SARS-Co V-2 virus,was first identified in December 2019 and has rapidly expanded to become a global pandemic[1].From then on,millions of people were infected,while the exact number of infections is difficult to determine,as not all people who are infected with the virus get tested,and some may not show any symptoms,and the number is rising as the pandemic *** sickness is characterized by fever,cough.

关键词： respiratory infected infection

Gastrointestinal tuberculosis is not associated with proton pump inhibitors:A retrospective cohort study

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World Journal of Gastroenterology 2013年第2期19卷 258-264页

作者： Kyoung Sup Hong Seung Joo Kang jong Kyoung Choi Ju Han kim Heewon Seo Suehyun Lee Jae-Woo Jung Hye-Ryun Kang Sang-heon Cho Joo Sung kim Department of Internal Medicine Drug Safety Monitoring CenterSeoul National University HospitalSeoul National University College of MedicineSeoul 110799South Korea Department of Internal Medicine Seoul National University HospitalSeoul National University College of MedicineSeoul 110799South Korea Division of Biomedical Informatics Systems Biomedical Informatics Research CenterSeoul National University College of MedicineSeoul 110799South Korea

AIM:To evaluate the effect of proton pump inhibitors(PPIs) on the development of gastrointestinal ***:All patients who were more than 20 years old and who had received a prescription for PPIs among those who visited Seoul National University Hospital from January 1,2005 to December 31,2009 were *** to the low sensitivity of the microbiologic test and the nonspecific pathologic findings,the diagnosis of gastrointestinal tuberculosis was confirmed through the presence of active ulcerations and the responses to anti-tuberculosis *** patients were divided into two groups according to treatment duration(group 1:≤ 3 mo;group 2:> 3 mo) and were followed up from the time they took the first prescription of PPIs until their last *** regression analysis was used to calculate the relative risks(RR) and 95%CI,adjusting for ***:Among the 61 834 patients exposed to PPIs(50 534 in group 1;11 300 in group 2),21 patients were diagnosed with PPI-associated gastrointestinal tuberculosis during 124 274 person-years of *** 21 patients,the 12 who revealed only scar changes in the colonoscopy were excluded from the statistical *** those who remained,2 were excluded because they underwent gastrointestinal endoscopy within 4 wk of the first prescription for *** exposure to PPI was associated with a higher mean age(55.0 ± 14.5 in group 1 vs 58.2 ± 13.3 in group 2,P < 0.001) and a higher Charlson co-morbidity index(0.50 ± 0.93 in group 1 vs 0.77 ± 1.14 in group 2,P < 0.001).The true incidence of active gastrointestinal tuberculosis was 0.65 per 1000 person-years in group 1 and 0.03 per 1 000 person-years in group *** the less-than-three-month PPI treatment period in group 1,the over-three-month PPI therapy period in group 2 was not associated with increased risk of acquiring gastrointestinal tuberculosis,after adjusting for age and co-morbidities,whereas the Charlson co-morbidity index was associated

关键词： Proton pump inhibitor Acid suppression Tuberculosis Gastrointestinal tuberculosis Tuberculous colitis

Human periodontal ligament stem cells repair mental nerve injury

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Neural Regeneration Research 2013年第30期8卷 2827-2837页

作者： Bohan Li Hun-jong Jung Soung-Min kim Myung-Jin kim Jeong Won Jahng jong-Ho Lee Department of Oral and Maxillofacial Surgery School of Dentistry Binzhou Medical College Department of Occupation and Environment Konkuk Postgraduate Medical School Department of Oral and Maxillofacial Surgery School of Dentistry Seoul National University Dental Research Institute Seoul National University

Human periodontal ligament stem cells are easily accessible and can differentiate into Schwann cells. We hypothesized that human periodontal ligament stem cells can be used as an alternative source for the autologous Schwann cells in promoting the regeneration of injured peripheral nerve. To validate this hypothesis, human periodontal ligament stem cells （1 × 106） were injected into the crush-injured left mental nerve in rats. Simultaneously, autologous Schwann cells （1 × 106） and PBS were also injected as controls. Real-time reverse transcriptase polymerase chain reaction showed that at 5 days after injection, mRNA expression of low affinity nerve growth factor receptor was sig-nificantaly increased in the left trigeminal ganglion of rats with mental nerve injury. Sensory tests, histomorphometric evaluation and retrograde labeling demonstrated that at 2 and 4 weeks after in-jection, sensory function was significantly improved, the numbers of retrograde labeled sensory neurons and myelinated axons were significantly increased, and human periodontal ligament stem cells and autologous Schwann cells exhibited similar therapeutic effects. These findings suggest that transplantation of human periodontal ligament stem cells show a potential value in repair of mental nerve injury.

关键词： neural regeneration peripheral nerve injury stem cells periodontal ligament stem cells mentalnerve Schwann cells cell transplantation sensory nerve neurotrophic factor neuroregeneration

Ballistic limit velocity of small caliber projectiles against SS400 steel plates:Live fire experiments and empirical models

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Defence Technology（防务技术） 2024年第11期41卷 22-34页

作者： jong-Hwan kim Seungwon Baik Jirui Fu Joon-Hyuk Park Mechanical&Systems Engineering Korea Military Academy574 Hwarang-roNowon-guSeoul17977South Korea Mechanical and Aerospace Engineering University of Central Florida4000 Central Florida BlvdOrlandoFL 32816United States

This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. Four different small caliber projectiles were tested against SS400 steel plates of 9 mm, 10 mm, and 12 mm thicknesses. The ballistic limit velocity was calculated using two standard methods, MIL-STD-662F and NIJ-STD-0101.06, and additionally using a support vector machine algorithm. The results show a linear relationship between the plate thickness and ballistic limit velocity. Further, the relative penetration performance among five different small caliber projectiles was analyzed using the Penetration Performance Ratio(PPR) introduced in this study, which suggests the potential of PPR to predict the ballistic limit velocity of other untested materials and/or different projectiles.

关键词： Live fire ballistic experiment SS400 Ballistic limit velocity Small caliber projectile