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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

Optimization of post-warranty sequential inspection for second-hand products

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Journal of Systems Engineering and Electronics 2017年第4期28卷 793-800页

作者： Dae-Kyung Kim Jae-Hak Lim dong Ho park Department of Statistics Chonbuk National University Department of Management & Accounting Hanbat National University Industry Academic Cooperation Foundation Hallym University

This paper considers an optimal sequential inspection schedule for a second-hand product after that the free nonrenewable warranty is expired. The length of warranty is prespecified and during the warranty period, the product is minimally repaired by the dealer when it fails. Following the expiration of the non-renewing warranty, the product is inspected and upgraded sequentially a fixed number of times at the expenses of the *** each inspection, the failure rate of the product is reduced proportionally so that the product is upgraded. The product is assumed to deteriorate as it ages and the replacement of the product occurs when a fixed number of inspections are rendered. In addition,the intervals between two successive inspections are assumed to decrease monotonically. The main objective of this paper is to determine the optimal improvement level to upgrade the product at each inspection so that the expected maintenance cost during the life cycle of the product is minimized from the perspective of the customer. Under the given cost structures, we derive an explicit formula to obtain the expected maintenance cost incurred during the life cycle of the product and discuss the method to find the optimal level of the improvement analytically in case the failure times follow the Weibull distribution. Numerical results are analyzed to observe the impact of relevant parameters on the optimal solution.

关键词： second-hand product sequential inspection upgrade action life cycle of the product expected maintenance cost free non-renewable warranty

Comparison of Antioxidant Activities in Black Soybean Preparations Fermented with Various Microorganisms

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Agricultural Sciences in China 2010年第7期9卷 1065-1071页

作者： QIN Yao JIN Xiao-nan park Heui dong Department of Food Science and Technology Kyungpook National University Daegu 702-701 Korea Applied Plant Stress Biology Lab/Divison of Biotechnology/College of Life Sciences and Biotechnology Korea University Seoul 136-713 Korea

Black soybeans [Glycine max（L.） Merrill] were fermented with various GRAS（generally recognized as safe） microorganisms,including Aspergillus sp.,Bacillus *** yeast（Issatchenkia orientalis） at 30°C for 3 *** antioxidant contents,including total phenolics and total flavonoids,and the antioxidant activities of 1,1-diphenyl-2-picrylhydrazine（DPPH）,ferric reducing antioxidant power（FRAP） and *** were analyzed in preparations of fermented black *** cultures proved to yield significant levels of antioxidants compared with non-fermented cultures（P 〈 0.05）.Fermented black soybean preparations possessed antioxidant activities could be attributed to the total phenolics and flavonoids present.

关键词： antioxidant activity black soybean microorganisms fermentation

Friction stir welding of 5052 aluminum alloy plates

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中国有色金属学会会刊：英文版 2009年第B9期19卷 23-27页

作者： Yong-Jai KWON Seong-Beom SHIM dong-Hwan park School of Materials Science and Engineering University of Ulsan Institute of E-Vehicle Technology University of Ulsan

Friction stir welding between 5052 aluminum alloy plates with a thickness of 2 mm was performed. The tool for welding was rotated at speeds ranging from 500 to 3000 r/min under a constant traverse speed of 100 mm/min. The results show that at all tool rotation speeds, defect-free welds are successfully obtained. Especially at 1000, 2000 and 3000 r/min, the welds exhibit very smooth surface morphologies. At 500, 1000, and 2000 r/min, onion ring structure is clearly observed in the friction-stir-welded zone (SZ). In addition, the onion ring structure region becomes wider as the tool rotation speed is increased. The gain size in the SZ is smaller than that in the base metal, and is decreased with a decrease of the tool rotation speed. In all tool rotation speeds, the SZ exhibits higher average hardness than the base metal. Especially at 500 r/min, the average hardness of the SZ reaches a level about 33% greater than that of the base metal. At 500, 1 000 and 2 000 r/min, the tensile strength of the friction stir welded (FSWed) plates is similar to that of the base metal (about 204 MPa). The elongation of the FSWed plates is lower than that of the base metal (about 22%). However, it is noticeable that the maximum elongation of about 21% is obtained at 1 000 r/min.

关键词：搅拌摩擦焊接铝合金板旋转速度焊接工具表面形貌环形结构抗拉强度伸长率

Evaluating the environmental efficiency of the *** industry using a directional distance function DEA approach

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Journal of Management Analytics 2021年第1期8卷 1-18页

作者： Yuan Xu Yong Shin park Ju dong park Wonjoo Cho Department of Transportation Logisticsand FinanceCollege of BusinessNorth Dakota State UniversityFargoNDUSA Department of Marketing Operationsand AnalyticsBill Munday School of BusinessSt.Edward’s UniversityAustinTXUSA Department of Maritime Police and Production System Gyeongsang National UniversityTongyeong-siGyeongsangnam-doRepublic of Korea Department of Environment and Resource Research Korea Rural Economic InstituteNaju-siJeollanam-doRepublic of Korea

This study applies a directional distance function(DDF)data envelopment analysis(DEA)model to measure the environmental efficiency of 12 *** 2013–2016 by considering flight delay and greenhouse gas(GHG)emissions as joint undesirable ***,the environmental efficiency of airlines is compared using the CCR DEA(without flight delay)and DDF DEA(with flight delay).We find that several airlines experienced substantial changes in environmental efficiency scores when flight delay is ***,a tobit regression is used to explore whether the environmental factors of fleet age,ownership type,freight traffic,market share,and carrier type affect airlines’environmental *** results demonstrate that all of these factors significantly influence airline performance.

关键词： Airline environmental efficiency directional distance function DEA airline sustainability tobit regression

Glucagon peptide-like 1 receptor (GLP-1R) expression per se: a new insight into neurodegenerative disease?

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Neural Regeneration Research 2015年第7期10卷 1055-1057页

作者： dong-il Kim Soo-hyun park College of Veterinary Medicine Chonnam National University

Glucagon peptide-like 1（GLP-1）and GLP-1 receptor（GLP-1R）：GLP-1 is an incretin hormone secreted from gut L ***-1 exerts its action through binding to its specific receptor,GLP-1R,which is a member of the G protein... 详细信息

关键词： GLP-1R a new insight into neurodegenerative disease expression per se Glucagon peptide-like 1 receptor

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Journal of Central South University 2011年第5期18卷 1602-1608页

作者： LEE Sang-Hyuk park Wook-Je JUNG dong-yean Department of Electrical and Electronic Engineering Xi'an Jiaotong-Liverpool University Institute for Information and Electronics Research Inha University253 Yonghyun-dongNam-GuIncheon402-751Korea Daeho Technology Korea Co. LtdChangwonGyeongnam641-773Korea

The similarity computations for fuzzy membership function pairs were carried *** number related knowledge was introduced,and conventional similarity was compared with distance based similarity *** usefulness of the proposed similarity measure was *** results show that the proposed similarity measure could be applied to ordinary fuzzy membership functions,though it was not easy to *** conventional results on the calculation of similarity for fuzzy membership pair,fuzzy membership-crisp pair and crisp-crisp pair were carried *** proposed distance based similarity measure represented rational performance with the heuristic point of ***,troublesome in fuzzy number based similarity measure for abnormal universe of discourse case was ***,the similarity measure computation for various membership function pairs was discussed with other conventional results.

关键词： similarity measure fuzzy number distance similarity evaluation fuzzy membership function

Pseudo NLP Joint Spam Classification Technique for Big Data Cluster

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Computers, Materials & Continua 2022年第4期71卷 517-535页

作者： WooHyun park Nawab Muhammad Faseeh Qureshi dong Ryeol Shin Department of Electrical and Computer Engineering Sungkyunkwan UniversitySuwon16419Korea Department of Computer Education Sungkyunkwan UniversitySeoul03063Korea

Spam mail classification considered complex and error-prone task in the distributed computing *** are various available spam mail classification approaches such as the naive Bayesian classifier,logistic regression and support vector machine and decision tree,recursive neural network,and long short-term memory ***,they do not consider the document when analyzing spam mail *** approaches use the bagof-words method,which analyzes a large amount of text data and classifies features with the help of term frequency-inverse document *** there are many words in a document,these approaches consume a massive amount of resources and become infeasible when performing classification on multiple associated mail documents ***,spam mail is not classified fully,and these approaches remain with ***,we propose a term frequency topic inverse document frequency model that considers the meaning of text data in a larger semantic unit by applying weights based on the document’s ***,the proposed approach reduces the scarcity problem through a frequency topic-inverse document frequency in singular value decomposition *** proposed approach also reduces the dimensionality,which ultimately increases the strength of document *** evaluations show that the proposed approach classifies spam mail documents with higher accuracy using individual document-independent processing *** evaluations show that the proposed approach performs better than the logistic regression model in the distributed computing environment,with higher document word frequencies of 97.05%,99.17%and 96.59%.

关键词： NLP big data machine learning TFT-IDF spam mail

Free radical scavenger effect of rebamipide in sperm processing and cryopreservation

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Asian Journal of Andrology 2003年第3期5卷 195-201页

作者： Nam Cheol park Hyun Jun park Kyeong Mi Lee dong Gil Shin Department of Urology College of Medicine Pusan National University Busan 602 739 KoreaDepartment of Urology College of Medicine Pusan National University Busan 602 739 KoreaDepartment of Urology College of Medicine Pusan National University Busan 602 739 KoreaDepartment of Urology College of Medicine Pusan National University Busan 602 739 Korea

Aim: To study the effect of rebamipide added to semen samples and cryoprotectant on reactive oxygen species (ROS) production. Methods: Semen samples from 30 fertile and healthy volunteers were collected by masturbation after 2 days - 3 days of abstinence. After liquefaction, the specimens were diluted with sperm wash media to a uniform density of 20×106/mL. Rebamipide was added to semen samples and cryoprotectant to a final concentration of 10 μmol/L, 30 μmol/L, 100 μmol/L or 300 μmol/L. Specimens were incubated at 37 ℃ in a 0.5 % CO2 incubator for 1 h or cryopreserved at -196 ℃ LN2 for 3 days. The sperm motility and viability and the levels of ROS and lipid peroxidation of sperm membrance were assessed before and after incubation and cryopreservation by means of computer assisted semen analyzer, eosin-nigrosin stain, chemiluminescence and thiobarbituric acid assay, respectively. Results: The sperm motility was significantly increased after incubation with 100 μmol/L and 300 μmol/L rebamipide (P0.05). The levels of ROS and lipid peroxidation in semen were significantly decreased in proportion to the concentrations of rebamipide both after incubation and cryopreservation (P<0.05). Conclusion: Rebamipide is an effective free radical scavenger in semen in vitro.

关键词： male infertility reactive oxygen species rebamipide

URANS simulations for a free-running container ship:Part 1. Turning-circle

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Journal of Hydrodynamics 2021年第3期33卷 421-447页

作者： dong-Hwan Kim Yugo Sanada Sungtek park Hamid Sadat-Hosseini Frederick Stern IIHR-Hydroscience and Engineering The University of IowaIowa CityUSA Costal Development and Ocean Energy Research Center Korea Institute of Ocean Science and TechnologyBusanKorea Mechanical Engineering University of North TexasDentonUSA

The incompressible unsteady Reynolds-averaged Navier-Stokes(URANS)simulations are performed for a free-running container ship in maneuvering conditions:the starboard and portside turning circle simulations with 35°rudder *** validation variables include trajectory,motions,and propeller performances,and the prediction shows acceptable agreements against the experimental *** the steady-state part of the turning,the inertial forces balancing the local forces are reported to quantitatively assess the centrifugal force which appears from the force equilibrium between the rudder,propeller,and the *** study on the local flow focuses on finding the correlations between the propeller inflow and the propeller performance to investigate the differences in propeller performances during the portside and starboard *** preliminary simulations,performed with the grid triplet,comprise propeller open-water,resistance,and self-propulsion simulations,from which the validation studies and the studies for the local force and the local flow are fulfilled and applied for the main *** propeller and rudder are fully discretized and controlled,mimicking the ***-set,overset approach and Mentor’s SST model are employed for the free-surface capturing,large motion prediction,and turbulence closure.

关键词： Turning-circle unsteady Reynolds-averaged Navier-Stokes(URANS) KRISO Container Ship(KCS) CFDShip-IOWA