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Difference in extrusion temperature dependences of microstructure and mechanical properties between extruded AZ61 and AZ91 alloys

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Journal of Magnesium and Alloys 2023年第5期11卷 1683-1696页

作者： Dong hee lee Gyo Myeong lee Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

The effects of extrusion temperature on the microstructure and tensile properties of extruded AZ61 and AZ91 alloys are investigated by subjecting them to hot extrusion at 300 and 400℃.Although the average grain size of the extruded AZ61 alloy slightly increases from 9.5 to 12.6μm with increasing extrusion temperature,its resultant microstructural variation is *** contrast,the average grain size of the extruded AZ91 alloy significantly increases from 5.7 to 22.5μm with increasing extrusion temperature,and the type of Mg17Al12 precipitates formed in it changes from fine dynamic precipitates with a spherical shape to coarse static precipitates with a lamellar *** the extrusion temperature increases,the tensile yield strength of the extruded AZ61 alloy increases from 183 to 197 MPa while that of the extruded AZ91 alloy decreases from 232 to 224 *** tensile elongations of the extruded AZ61 and AZ91 alloys decrease with increasing extrusion temperature,but the degree of decrease is significant in the latter *** different extrusion temperature dependences of the tensile properties of the extruded AZ61 and AZ91 alloys are discussed in terms of their microstructural characteristics,strengthening mechanisms,and crack initiation sites.

关键词： Mg-Al-Zn alloys Extrusion temperature Precipitation Strengthening mechanism Tensile properties

Factors associated with strabismus after cataract extraction and primary intraocular lens implantation in congenital cataracts

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International Journal of Ophthalmology(English edition) 2014年第3期7卷 522-527页

作者： soo Jung lee Wan-soo Kim Department of Ophthalmology Haeundae Paik Hospital

AIM:To evaluate factors associated with the development of strabismus after cataract extraction and primary intraocular lens ***:The medical records of 122 patients,aged1.5mo to 9y,who had undergone cataract extraction with primary intraocular lens implantation between January1993 and August 2011 were *** patients(17 eyes)with strabismus before cataract surgery were *** were divided into those with congenital bilateral cataracts(64 patients,128 eyes)and those with unilateral cataracts(44 patients,44 eyes).The associations between the development of strabismus and age at cataract surgery,pre-and post-cataract extraction corrected distance visual acuity(CDVA),interocular CDVA difference,nystagmus,surgical method,and secondary cataract were ***:Factors significantly associated with the development of strabismus included age at cataract surgery(≤1y),preoperative mean CDVA≤20/100,presence of nystagmus in the bilateral cataract group and postoperative interocular CDVA difference>20/70 in the unilateral *** CDVA≤20/100 and preservation of posterior capsule,and presence of secondary cataract were significant factors in both ***:Children with congenital cataracts should be monitored carefully after cataract surgery for the development of strabismus,especially when they underwent surgery at age≤1y,and they have nystagmus,large postoperative interocular CDVA difference,poor preoperative and postoperative CDVA,preservation of the posterior capsule,or secondary cataract.

关键词： strabismus congenital cataract nystagmus

Factors influencing stereoacuity levels after surgery to correct unilateral developmental cataracts in children

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International Journal of Ophthalmology(English edition) 2013年第3期6卷 331-336页

作者： soo Jung lee Wan-soo Kim Department of Ophthalmology Haeundae Paik Hospital

·AIM: To evaluate factors influencing stereoacuity after surgery to correct unilateral developmental pediatric cataracts. ·METHODS: We retrospectively surveyed 110 patients who had undergone removal of unilateral acquired developmental cataracts and primary posterior chamber intraocular lens implantation between February 1992 and December 2009. In all patients, stereoacuity was assessed using the Titmus test at the last follow -up period of minimum 2 years after surgery. Patients were divided into two groups according to the extent of stereoacuity : group 1 ( = 42 ) had stereoacuity values ≤ 100sec/arc and group 2 ( =68) values >100sec/arc. The values of ten parameters associated with stereoacuity were measured in each group: Cataract types, preoperative best corrected visual acuity (BCVA) of the affected eyes, preoperative inter -ocular difference of BCVA, age at cataract surgery, operative method, secondary cataract, postoperative strabismus, postoperative BCVA of the affected eyes, postoperative inter-ocular difference of BCVA, and anisometropia. ·RESULTS: The extent of stereoacuity was significantly associated with both operative method and secondary cataract ( =0.000 and =0.016, respectively). All patients in whom the posterior capsule was preserved, had poor stereoacuity >100sec/arc. Significant correlations with the extent of stereoacuity were found with postoperative strabismus ( =0.048),postoperative BCVA of the affected eyes ( =0.002), anisometropia ( =0.034). ·CONCLUSION: Postoperative stereoacuity was better in patients who underwent either optic capture or anterior vitrectomy after posterior continuous curvilinear capsulorhexis, and who didn’t develop secondary cataracts or strabismus postoperatively. Furthermore, postoperative BCVA of the affected eyes, and anisometropia influenced the stereoacuity of the patients surgically treated for unilateral developmental pediatric cataracts. ·

关键词： anisometropia developmental cataract secondary cataract stereoacuity stereopsis strabismus unilateral pediatric cataract visual acuity

Fermented rice bran prevents atopic dermatitis in DNCB-treated NC/Nga mice

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The Journal of Biomedical Research 2016年第4期30卷 334-343页

作者： Evelyn Saba Chun hee lee Da Hye Jeong Kija lee Tae-Hwan Kim Seong-soo Roh Seung-Hyung Kim Man hee Rhee Department of Veterinary Medicine College of Veterinary MedicineKyungpook National UniversityDaegu 41566Korea Enzyme LAPA Co. Cheonan 31164 Korea College of Korean Medicine Daegu Haany University Daegu 42158Korea Institute of Traditional Medicine&Bioscience Daejeon University Daejeon 34520 Korea

The fermentation of natural plants has a favorable effect on the functional and biological activities of living systems. These include anti-oxidative, anti-inflammatory, and anti-platelet aggregation activities. This is attributed to the chemical conversion of the parent plants to functional constituents, which show more potent biological activity. In our study, rice bran along with oriental medicinal plants （Angelicae gigantis, Cnidium officinale, Artemisia princeps, and Camellia sinensis） was fermented by Lactobacillus rhamnosus and Pichia deserticola （FRBE）. We evaluated the effects of oral administration of FRBE on atopic dermatitis in 1-chloro-2,4-dinitrobenzene （DNCB）-treated NC/Nga mice. FRBE significantly ameliorated the macroscopic and microscopic appearance of skin lesions in DNCB-induced atopic dermatitis and reduced levels of serum immunoglobulin E and the differential white blood cell count. In addition, it reduced skin thickness compared to that of atopic dermatitis-affected skin. FRBE treatment also reduced mast cell incorporation in skin lesions of atopic dermatitis. The total cell number in dorsal skin tissue and the axillary lymph node increased following DNCB application, and this was normalized by FRBE treatment. Moreover, it decreased the levels ofCD8＋ helper T cells and Gr-1 ＋/CD1 lb＋ B cells in peripheral blood mononuclear cells and skin lesions in DNCB-induced atopic dermatitis. Using real-time polymerase chain reaction analysis, we demonstrated that FRBE significantly inhibited mRNA expression of cytokines （e.g., interleukin-5 and interleukin-13） and cyclooxygenase-2 in AD skin lesions. These results suggest that FRBE could be a valuable herbal remedy for the treatment of atopic dermatitis.

关键词： fermentation rice bran gas chromatography Lactobacillus rhamnosus Pichia deserticola

Measurement of the time required for termites to pass each other in tunnels of different curvatures

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Insect Science 2013年第4期20卷 550-556页

作者： Seungwoo Sim Sang-hee lee Division of Fusion Convergence of Mathematical Sciences National Institute for Mathematical Sciences Daejeon South Korea

Subterranean termites construct complex tunnel networks for foraging. During travel in the tunnels, termites often encounter one another when passing in opposite directions. Such encounters are likely to affect the ＂movement efficiency,＂ which is the time required for a termite to travel a certain distance in a tunnel. In this study, we explored how individual-individual encounters affect movement efficiency in tunnels by measuring the time （v） taken by two termites to pass one another in tunnels of different curvatures. Artificial tunnels of 5 cm in length and variable widths （W） of 2, 3, or 4 mm were made. Tunnel distance （D） was 2, 3, 4, or 5 cm. When D had a higher value, curvature was lower. When W = 2, T was significantly shorter in the tunnel with D = 5 than in tunnels ofD = 2, 3, or 4, whereas v was statistically the same for D = 2, 3 and 4. When W = 3, r was shorter in the tunnel with D = 5 than for D = 3 and 4, while ~ was longer in the tunnel with D = 2 than for D = 3 and 4. When W = 4, r was longer in the tunnels with D = 2 and 3 than for D = 4 and 5. Based on these observations, 3 types of termite behavior were identified： biased walking, backward walking, and zigzag walking. We considered these results in relation to foraging efficiency.

关键词： individual-individual encounters movement efficiency termites tunnelcurvature turmel network

Flash‑Induced High‑Throughput Porous Graphene via Synergistic Photo‑Effects for Electromagnetic Interference Shielding

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纳微快报:英文版 2023年第11期15卷 1-18页

作者： Jin soo lee Jeong‑Wook Kim Jae hee lee Yong Koo Son Young Bin Kim Kyoohee Woo Chanhee lee Il‑Doo Kim Jae Young Seok Jong Won Yu Jung Hwan Park Keon Jae lee Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology(KAIST)291 Daehak‑roYuseong‑guDaejeon 34141Republic of Korea School of Electrical Engineering Korea Advanced Institute of Science and Technology(KAIST)291 Daehak‑roYuseong‑guDaejeon 34141Republic of Korea Department of Printed Electronics Nano‑Convergence Manufacturing Systems Research DivisionKorea Institute of Machinery and Materials(KIMM)156 Gajeongbuk‑RoYuseong‑GuDaejeon 34103Republic of Korea Department of Mechanical System Design Engineering Seoul National University of Science and Technology232 Gongneung‑roNowon‑guSeoul 01811Republic of Korea Department of Mechanical Engineering(Department of Aeronautics Mechanical and Electronic Convergence Engineering)Kumoh National Institute of Technology61 Daehak‑roGumiGyeongbuk 39177Republic of Korea

Porous 2D materials with high conductivity and large surface area have been proposed for potential electromagnetic interference(EMI)shielding materials in future mobility and wearable applications to prevent signal noise,transmission inaccuracy,system malfunction,and health ***,we report on the synthesis of lightweight and flexible flash-induced porous graphene(FPG)with excellent EMI shielding *** broad spectrum of pulsed flashlight induces photo-chemical and photo-thermal reactions in polyimide films,forming 5×10 cm^(2)-size porous graphene with a hollow pillar structure in a few *** resulting material demonstrated low density(0.0354 g cm^(−3))and outstanding absolute EMI shielding effectiveness of 1.12×10^(5) dB cm^(2) g^(−1).The FPG was characterized via thorough material analyses,and its mechanical durability and flexibility were confirmed by a bending cycle ***,the FPG was utilized in drone and wearable applications,showing effective EMI shielding performance for internal/external EMI in a drone radar system and reducing the specific absorption rate in the human body.

关键词： Porous graphene Flash lamp Photo-pyrolysis High-throughput Electromagnetic interference shielding

A study on the interference effects for tidal current power rotors

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Science China(Technological Sciences) 2010年第11期53卷 3094-3101页

作者： Chul-hee JO Kang-hee lee Jin-Young YIM Department of Naval Architecture & Ocean Engineering Inha University

Due to global warming, the need to secure an alternative resource has become more important nationally. With the high tidal range of up to 9.7 m on the west coast of Korea, numerous tidal current projects are being planned and constructed. To extract a significant quantity of power, a tidal current farm with a multi-arrangement is necessary in the ocean. The rotor, which initially converts the energy, is a very important component because it affects the efficiency of the entire system, and its performance is determined by various design variables. The power generation is strongly dependent on the size of the rotor and the incoming flow velocity. However, the interactions between devices also contribute significantly to the total power capacity. Therefore, rotor performance considering the interaction problems needs to be investigated for generating maximum power in a specific field. This paper documents a performance study of devices considering the interference between rotating rotors with axial, transverse and diagonal arrangements.

关键词： TCP (tidal current power) renewable energy interference effect rotor CWC (circulation water channel) CFD (computational fluid dynamics)

Synthesis of tin nanoparticles through modified polyol process and effects of centrifuging and drying on nanoparticles

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中国有色金属学会会刊：英文版 2012年第S3期22卷 707-711页

作者： Sang-soo Chee Jong-Hyun lee Department of Materials Science and Engineering Seoul National University of Science and Technology

Sn nanoparticles with average diameter of 13.1 nm were synthesized by modified polyol process,and their melting point was observed to be about 40 °C less than that of bulk *** though Sn nanoparticles are solid and covered with thin PVP capping and oxide layer,Sn nanoparticles in solution agglomerate upon centrifugation,resulting in a melting point *** to stickiness of the PVP capping layer,extensive aggregation between Sn nanoparticles was observed after ***,the aggregation behavior did not further influence the melting point,because actual agglomeration did not occur in the aggregates.

关键词： tin nanoparticle melting point centrifugation agglomeration aggregation

Comparison of soil bacterial diversity and community composition between clear-cut logging and control sites in a temperate deciduous broad-leaved forest in Mt. Sambong, South Korea

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Journal of Forestry Research 2020年第6期31卷 2367-2375页

作者： Byeong-Ju lee soo Hyung Eo Department of Forest Resources Kongju National UniversityYesanChungnam 32439Republic of Korea

Deforestation or clear-cut logging affects forest ecosystems,including soil microbial *** purpose of this study was to investigate the effects of clearcut logging on the soil bacterial community in a temperate deciduous broad-leaved forest on ***,South *** investigated the physicochemical characteristics and bacterial diversity of the soil in clear-cut logging and control *** available phosphorus(AP)level in soil was significantly lower in the clear-cut sites than in the control;however,the other physicochemical properties of soil were similar at the two *** examining the bacterial 16S rRNA gene using next-generation sequencing,we found that the number of bacterial taxa at the species and phylum level were similar at the control and clear-cut *** with the high resilience of bacterial communities and absence of change in the soil physicochemical properties—with the exception of AP—we found similar levels of bacterial diversity at the two *** most taxa showed similar composition ratios at the control and the clear-cut sites,some taxa such as Deltaproteobacteria,Ktedonobacteriales,Myxocccales,Polyangiaceae,Pedosphaera_f,and Solibacter showed differences after clear-cut *** conclude that AP was significantly associated with those bacterial taxa that showed differences in their composition ratios following clear-cut logging.

关键词： Forest soil Metagenomics Pyrosequencing Soil physicochemical characteristics