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Break-up Characteristics of Gelled Propellant Simulants with Various Gelling Agent Contents

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Journal of Thermal Science 2010年第6期19卷 545-552页

作者： Inchul lee Jaye koo Graduate Student Korea Aerospace University School of Aerospace and Mechanical Engineering Korea Aerospace University

Gel propulsion systems have many advantages with respect to high performance, the energy management of liquid propulsion systems, storability, high density impulse, and low leakage of liquid propellants. The atomization process provides sufficient contact surface area between the gelled fuel and oxidizer jets. It is important to study how injection characteristics of gelled propellants are related with break-up and spray distribution. The break-up and mixing processes are very important in achieving maximum efficiency and necessitate the careful study of combustion instability. Gelled propellants are non-Newtonian fluids in which the viscosity is a function of the shear rate, and they have a high dynamic shear viscosity which depends on the amount of gelling agent contents. The present study has focused on the break-up process, wave development of ligament and liquid sheets formed by impinging jets with various gelling agent contents. Especially, the break-up processes of the impinging jets at the initial conditions are studied. The break-up process of like-on-like doublet impinging jets are experimentally characterized using non-Newtonian liquids which are mixed by ionized water 98.5 wt%, Carbopol 941 0.5wt% or 1.0wt%, and NaOH(concentration 10%) 1.0wt%. For the like-on-like doublet injector, the generation of a liquid sheet at the impinging point of two jets was observed. The spray shape with elliptical pattern is distributed in a perpendicular direction to the momentum vectors of the jets. Gelled propellant simulants with high viscosity jets are more stable and produce less pronounced surface waves than low viscosity jets. Generally, the break-up length decreased due to the increasing Reynolds number. However, surface waves and atomized droplets increased. Gelled propellant simulants from like-on-like doublet impinging jets have the spray shape of closed rim patterns at low pressure. Also, the rim patterns of spray have no disturbances on the spray sheet. As the

关键词： gelled propellant simulants storability low leakage impinging injector rimless pattern wave-like structure

Ethanol extract from Gynostemma pentaphyllum ameliorates dopaminergic neuronal cell death in transgenic mice expressing mutant A53T human alpha-synuclein

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Neural Regeneration Research 2020年第2期15卷 361-368页

作者： Hyun Jin Park Ting Ting Zhao Seung Hwan Kim Chong Kil lee Bang yeon Hwang Ky.ng eun lee My.ng koo lee Department of Pharmacy College of PharmacyChungbuk National UniversityCheongjuRepublic of Korea 2Research Center for Bioresource and Health College of PharmacyChungbuk National UniversityCheongjuRepublic of Korea Department of Social Physical Education Songwon UniversityGwangjuRepublic of Korea

Gynostemma(G.) pentaphyllum(Cucurbitaceae) contains various bioactive gypenosides. Ethanol extract from G. pentaphyllum(GP-EX) has been shown to have ameliorative effects on the death of dopaminergic neurons in animal models of Parkinson’s disease(PD) induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-and 6-hydroxydopamine. PD patients exhibit multiple symptoms, so PD-related research should combine neurotoxin models with genetic models. In the present study, we investigated the ameliorative effects of GP-EX, including gypenosides, on the cell death of dopaminergic neurons in the midbrain of A53 T α-synuclein transgenic mouse models of PD(A53 T). Both GP-EX and gypenosides at 50 mg/kg per day were orally administered to the A53 T mice for 20 weeks.α-Synuclein-immunopositive cells and α-synuclein phosphorylation were increased in the midbrain of A53 T mice, which was reduced following treatment with GP-EX. Treatment with GP-EX modulated the reduced phosphorylation of tyrosine hydroxylase, extracellular signal-regulated kinase(ERK1/2), Bcl-2-associated death promoter(Bad) at Ser112, and c-Jun N-terminal kinase(JNK1/2) due to α-synuclein overexpression. In the A53 T group, GP-EX treatment prolonged the latency of the step-through passive avoidance test and shortened the transfer latency of the elevated plus maze test. Gypenosides treatment exhibited the effects and efficacy similar to those of GP-EX. Taken together, GP-EX, including gypenosides, has ameliorative effects on dopaminergic neuronal cell death due to the overexpression of α-synuclein by modulating ERK1/2, Bad at Ser112, and JNK1/2 signaling in the midbrain of A53 T mouse model of PD. Further studies are needed to investigate GP-EX as a treatment for neurodegenerative synucleinopathies, including PD. This study was approved by the Animal Ethics Committee of Chungbuk National University(approval No. CBNUA-956-16-01) on September 21, 2016.

关键词： A53T α-synuclein genetic mice ERK1/2 gynostemma pentaphyllum gypenosides Parkinson’s disease retention transfer latency time

Contrast in Fluid M etallogeny between the Tianmashan Au-S Deposit and the Datuanshan Cu Deposit in Tongling,Anhui Province

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Acta Geologica Sinica(English Edition) 2003年第1期77卷 116-124页

作者： lee Hyun koo Depatment of Geology Chungnam National University 220 Kungdong Yuseong Ku Taejon 305-764 Republic of Korea

A comprehensive contrast of ore-forming geological background and ore-forming fluid features, especially fluid ore-forming processes, has been performed between the Tianmashan and the Datuanshan ore deposits in Tongling, Anhui Province. The major reasons for the formation of the stratabound skarn Au-S ore deposit in Tianmashan and the stratabound skarn Cu ore deposit in Datuanshan are analyzed in accordance with this contrast. The magmatic pluton in Tianmashan is rich in Au and poor in Cu, but that in Datuanshan is rich in Cu and Au. The wallrock strata in Tianmashan contain Au-bearing pyrite layers with some organic substance but those in Datuanshan contain no such layers. Moreover, the ore-forming fluids in Tianmashan are dominantly magmatic ones at the oxide and sulfide stages, but those with high content of Cu in Datuanshan are mainly groundwater fluids. In addition, differences in compositional evolution and physicochemical condition variation of the ore-forming fluids result in gradual dispersion

关键词： fluid inclusion fluid ore-forming process contrast in fluid metallogeny Au-S ore deposit Cu ore deposit magmatic fluid groundwater fluid Tongling Anhui Province

Disintegration Process and Performance of a Coaxial Porous Injector

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Journal of Thermal Science 2016年第5期25卷 394-401页

作者： Keonwoong lee Dohun Kim Jaye koo Graduate School Korea Aerospace University School of Aerospace and Mechanical Engineering Korea Aerospace University

In order to understand the breakup performance of coaxial porous injectors,the sprays of coaxial porous injectors with two different porous material cylinder lengths were compared with those of conventional shear coaxial *** allow comparison,the wall injection lengths were designed to be equivalent to the value of the recess *** flow sprays were visualized using back-lit photography methods and analyzed quantitatively with a laser diffraction apparatus,in order to study the effects of the momentum flux ratio and Weber number on the breakup for each type of *** case of the shear coaxial injector,the large liquid core was observed in low air mass flow rate ***,the destabilization of the liquid jet from the coaxial porous injector is almost complete within the inner region,near the injector face ***,better breakup performance in low gas flow rate condition was obtained when the porous cylinder length decreased,while the shear coaxial injectors showed better breakup efficiency when the recess length *** conclusion,the different breakup process caused by the radial momentum in the inner region of the porous injector disintegrated the liquid core.

关键词： Coaxial porous injector Sauter mean diameter Droplet size distribution

Breakup Structure of Two-phase Jets with Various Momentum Flux from a Porous Injector

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Journal of Thermal Science 2014年第1期23卷 60-67页

作者： Inchul lee Dohun Kim Jaye koo Graduate Student Korea Aerospace University School of Aerospace and Mechanical Engineering Korea Aerospace University

Spray structure and atomization characteristics were investigated through a comparison of a porous and a shear coaxial injector. The porous injector shows better atomization performance than the shear coaxial injector. To in- crease atomization performance and mixing efficiency of two-phase jets, a coaxial porous injector which can be applicable to liquid rocket combustors was designed and tested. The characteristics of atomization and spray from a porous and a shear coaxial injector were characterized by the momentum flux ratio. The breakup mechanism of the porous injector is governed by Taylor-Culick flow and axial shear forces. Momentum of injected gas flow through a porous material which is composed of sintered metal is radically transferred to the center of the liquid column, and then liquid column is effectively broken up. Although the shapes of spray from porous and shear co- axial jets were similar for various momentum ratio, spray structures such as spray angle and droplet sizes were different. As increasing the momentum flux ratio, SMD from the porous injector showed smaller value than the shear coaxial injector

关键词： Porous injector Shear coaxial injector Breakup mechanism Momentum flux ratio

Mixing Characteristics of Pulsed Air-assist Liquid Jet into an Internal Subsonic Cross-flow

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Journal of Thermal Science 2010年第2期19卷 136-140页

作者： Inchul lee youngsu Kang Jaye koo Graduate Student Korea Aerospace University School of Aerospace and Mechanical Engineering Korea Aerospace University

Penetration depth,spray dispersion angle,droplet sizes in breakup processes and atomization processes are very important parameters in combustor of air-breathing *** processes will enhance air/fuel mixing inside the *** results from the pulsed air-assist liquid jet injected into a cross-flow are *** experiments were conducted to a range of cross-flow velocities from 42～136 m/*** is injected with 0～300kPa,with air-assist pulsation frequency of 0～*** frequency was modulated by solenoid *** Doppler Particle Analyzer(PDPA) was utilized to quantitatively measuring droplet ***-speed CCD camera was used to obtain injected spray *** air-assist liquid jet will offer rapid mixing and good liquid jet ***-assist makes a very fine droplet which generated mist-like *** air-assist liquid jet will introduce additional supplementary turbulent mixing and control of penetration depth into a cross-flow *** results show that pulsation frequency has an effect on penetration,transverse velocities and droplet *** experimental data generated in these studies are used for a development of active control strategies to optimize the liquid jet penetration in subsonic cross-flow conditions and predict combustion low frequency instability.

关键词： cross-flow penetration pulsed air-assist liquid jet pulsation frequency

Safety assessment of condensed phosphate intake from fishery and processed marine food products in Korea with respect to gender,age,and region

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Food Quality and Safety 2021年第2期5卷 161-169页

作者： Hy.ng Soo Kim Dae y.ng Jang ye Ji koo eun Chul Pack Seung Ha lee Dal Woong Choi Health Science Research Center Korea UniversitySeoulRepublic of Korea department of Public Health Sciences Graduate SchoolKorea UniversitySeoulRepublic of Korea School of Health and Environmental Sciences Korea UniversitySeoulRepublic of Korea and department of Health and Safety Convergence Science Graduate SchoolKorea UniversitySeoulRepublic of Korea.

Condensed phosphates are used as food additives,especially in marine products and meat,to improve food *** import and consumption of fishery and processed marine food products in Republic of Korea have reportedly increased by~5 per cent ***,processed marine food products are often intentionally adulterated with excessive amounts of condensed phosphates to increase their *** intake of condensed phosphates via consuming processed marine food products can lead to various adverse effects on human health due to anionic ***,we conducted a safety assessment of condensed phosphates in 14 types of fishery and processed marine food products in Korea for the first *** analysis of various factors including gender,age,and region was also performed,and the risk level of exposure for each group was *** assessments by age and gender indicated that infants were at the highest *** the regional safety assessment,Chungnam,the most inland region,showed the lowest *** both the general and the high-intake groups(95th percentile)in all classifications,the risk was lower(ypes of processed marine products in Korea was confirmed to be safe for human consumption.

关键词： Condensed phosphates safety assessment ion chromatography fishery and processed marine food products

Fabrication of sintering-free flexible copper nanowire/ polymer composite transparent electrodes with enhanced chemical and mechanical stability

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Nano Research 2016年第7期9卷 2162-2173页

作者： Cho Rong Chu Changsoo lee Jahyun koo Hyuck Mo lee Department of Materials Science and Engineering KAIST 291 Daehak-ro Yuseong-gu Daejeon 305-701 Republic of Korea

The thermal decomposition synthesis of long copper nanowires （CuNWs） was achieved by controlling the synthesis parameters. A detailed study was performed to determine the effect of the molar ratio of copper chloride to nickel acetylacetonate, temperature, and stirring rate on the final shape of the products. Transparent electrodes （TEs） were fabricated by wet treatment with acetic acid （AA）, without using a sintering process. The low oxidation stability and high surface roughness are the main disadvantages of the CuNW TEs, which limit their applications. In order to overcome these issues, we prepared CuNW/polymer composite TEs by partial embedding of the CuNWs into poly（methyl methacrylate）（PMMA） on poly（ethylene terephthalate）（PET） substrates. The CuNW/PMMA composite TEs exhibit excellent optoelectronic performance （91.3% at 100.7 ff2/sq）, low surface roughness （4.6 nm in height）, and good mechanical and chemical stability as compared with CuNW TEs. On the basis of these properties, we believe that CuNW-based composite TEs could serve as low-cost materials for a wide range of new optoelectronic devices.

关键词： copper nanowires nanowire/polymercomposite transparent electrode chemical stability mechanical stability

Development and characterization of novel polymorphic microsatellite markers for the Korean freshwater snail Semisulcospira coreana and cross-species amplification using next-generation sequencing

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Journal of Oceanology and Limnology 2020年第2期38卷 503-508页

作者： yeon Jung PARK Mi Nan lee eun-Mi KIM Jung youn PARK Jae koo NOH Tae-Jin CHOI Jung-Ha KAng Biotechnology Research Division National Institute of Fisheries ScienceBusan 46083Republic of Korea Department of Microbiology Pukyoung National UniversityBusan 48513Republic of Korea

Korean freshwater snails of the genus Semisulcospira are widely distributed across East *** has been a very popular nutritional food in Korea,and is an ecologically important water quality indicator because it lives only in clean ***,no microsatellite markers have been generated to study the population genetic diversity of this *** the present study,we developed and characterized 18 novel microsatellite loci from Semisulcospira coreana genomic *** microsatellites were isolated using 454 GS-FLX titanium sequencing and 18 markers were used for genotyping in *** addition,we also tested the cross-species transferability of the microsatellite markers in four additional Semisulcospira *** identified 18 polymorphic loci and the number of alleles per loci,and their polymorphism information content values ranged from 2 to 17 and 0.203 to 0.902,*** observed and expected heterozygosities of the loci ranged from 0.063 to 0.924 and 0.226 to 0.924,*** to the analysis of the cross-species transferability of these markers,four species,***,***,***,and ***,showed a very high transferability(80%–85%).These results show that this set of nuclear markers could be useful for population genetics studies of this species and closely related species.

关键词： Semisulcospira next-generation sequencing(ngS) microsatellite markers cross-species transferability