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Efects on nano zero-valent iron reactivity of interactions between hardness, alkalinity, and natural organic matter in reverse osmosis concentrate

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Journal of Environmental Sciences 2013年第11期25卷 2177-2184页

作者： Yuhoon hwang Hang-sik Shin Department of Environmental Engineering Technical University of Denmark Department of Civil and Environmental Engineering Korea Advanced Institute of Science and Technology

Nanoscale zero-valent iron （NZVI） is considered to have potential to reduce nitrate in the concentrate generated by high pressure membrane processes aimed at water reuse. However, it is necessary to verify the effect of the matrix components in the concentrates on NZVI reactivity. In this study, the influence of hardness, alkalinity, and organic matter on NZVI reactivity was evaluated by the response surface method （RSM）. Hardness （Ca/＋） had a positive effect on NZVI reactivity by accelerating iron corrosion. In contrast, alkalinity （bicarbonate; HCO3） and organic matter （humic acid; HA） had negative effects on NZVI reactivity due to morphological change to carbonate green rust, and to competitive adsorption of HA, respectively. The validity of the statistical prediction model derived from RSM was confirmed by an additional confirmation experiment, and the experimental result was within the 95% confidential interval. Therefore, it can be indicated that the RSM model produced results that were statistically significant.

关键词： nitrate reduction concentrate treatment response surface method nano zero valent iron

Measurement of alumina film induced ablation of internal insulator in solid rocket environment

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Defence Technology（防务技术） 2023年第11期29卷 181-192页

作者： Ji-Yeul Bae In sik hwang Yoongoo Kang Agency for Defense Development 160488th Bukyuseong-streetDaejeonSouth Korea

This study investigates the ablation of internal insulation induced by the deposition of an alumina film with different lateral film speeds.A sub-scale test solid rocket motor(SRM)was designed in an impinging jet configuration to form an alumina film on the sample and to encourage the lateral movement of the film by a high-speed wall *** static fire tests of the test SRM were conducted with six different jet velocities(V_(jet)=100 m/s,150 m/s,200 m/s,268 m/s,330 m/s,and 450 m/s)that indirectly affected the velocity of the wall jet and the deposition rate of alumina *** ablation velocity was deduced from the difference in the sample thickness after a test using a coordinate measuring *** droplet deposition mass flux and wall jet velocity were obtained via two-phase flow simulation with the same jet velocity and effective *** a result,the characteristics of alumina-induced ablation and the changes in ablation with jet velocities were *** area within0.8×jet diameter was focused upon,where the ratio of ablation velocity to incoming alumina mass was constant for each jet velocity,and showed a similarity in jet *** the ablation velocity was increased from 2.05 to 9.98 mm/s with increasing jet velocity,the ratio of the ablation velocity and alumina mass flux decreased from 1.07×10^(-4)to 0.49×10^(-4)m^(3)/kg as Al_(2)O_(3)-C reactions became less efficient with a reduced residence time of the *** the decrease in residence time by the wall jet is more pronounced for slow reactions involved in Al_(2)O_(3)-C reactions,fast reactions in Al_(2)O_(3)-C reactions are less affected and result in a convergence of the volumetric rate of ablation per unit mass of alumina.

关键词： Internal insulation Solid rocket motor Ablation Alumina

Brazilin and Caesalpinia sappan L. extract protect epidermal keratinocytes from oxidative stress by inducing the expression of GPX7

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Chinese Journal of Natural Medicines 2018年第3期16卷 203-209页

作者： hyung Seo hwang Joong Hyun Shim Department of Oriental Cosmetic Science Semyung University

Caesalpinia sappan L., belonging to the family Leguminosae, is a medicinal plant that is distributed in Southeast Asia. The dried heartwood of this plant is used as a traditional ingredient of food, red dyes, and folk medicines in the treatment of diarrhea, dysentery, tuberculosis, skin infections, and inflammation. Brazilin is the major active compound, which has exhibited various phar- macological effects, including anti-platelet activity, anti-hepatotoxicity, induction of immunological tolerance, and anti-inflammatory and antioxidant activities. The present study aimed to evaluate the antioxidant activity and expression of antioxidant enzymes of C. sappan L. extract and its major compound, brazilin, in human epidermal keratinocytes exposed to UVA irradiation. Our results indi- cated that C. sappan L. extract reduced UVA-induced H202 production via GPX7 activation. Moreover, brazilin exhibited anfioxidant effects that were similar to those of C. sappan L. via glutathione peroxidase 7 （GPX7）, suggesting that C. sappan L. extract and its natural compound represent potential treatments for oxidative stress-induced photoaging of skin.

关键词： Caesalpinia sappan L. Brazilin Ultraviolet GPX7 Antioxidative

Transportation problem: A special case for linear programing problems in mining engineering

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International Journal of Mining Science and Technology 2012年第3期22卷 371-377页

作者： Ali Mahrous A.M. sik Yang hyung Energy and Resources Engineering Department College of Engineering Chonnam National University

In real world applications the supply, the demand and the transportation cost per unit of the quantities in a transportation problem are hardly specified precisely because of the changing economic and environmental conditions. It is also important that the time required for transportation should be minimum. In this paper a method has been proposed for the minimization of transportation costs. Supply and transportation costs per unit of the quantities are also determined. The present study was carried out to evaluate the quality of gravel to know its suitability for aggregate (raw material for concrete and road). The samples of gravel were analyzed for petrographic, physical, mechanical and chemical properties. Samples were categorized as quartzite group and carbonate group according to ASTM standard 295. Among these, samples of quartzite group were found dominant. The petrography examination of gravels which was carried out constituted of opal, tridymite, chalcedony, crystobalite and alkali carbonates rocks. Those minerals react with alkalis in cement leading to expansion and cracking of concrete. Other components such as sulfides, sulfates, halites, iron oxides, clay minerals and anhydrites are examined, which might be present as coating and impurities. The present study indicated that all samples are suitable for concrete making and obtain the optimum solution for transporting these materials from quarries to cities with minimum cost according to Egyptian Code.

关键词： Linear programingTransportation problemAggregatesGravel

An Experimental Study on the Behavior of Square Concrete-Filled High Strength Steel Tube Columns

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Journal of Iron and Steel Research International 2011年第S1期18卷 878-882页

作者： hyung-suk Jung Chang-sik Choi Department of sustainable architectural engineering Hanyang UniversitySeoulKorea Department of architectural engineering Hanyang UniversitySeoulKorea

The paper presents an experimental study on the behavior of square concrete-filled high strength steel tube columns until *** specimens were tested to investigate the effect of high strength steel and plain strength concrete on the load carrying capacity of the square concrete-filled steel tube *** effect of the concrete which filled in the steel tube was also ***,the effect of high strength steel and the presence of concrete were also *** main parameters in the tests were:(1) the ultimate strength of steel (800 Mpa),(2) the presence of concrete in steel tube (hollow steel tube and concrete-filled steel tube),and (3) slender *** main objectives of these tests were three-step:(1) to describe a series of tests on composite columns,(2) to analyze the influence of several parameters,and (3) to compare the accuracy of the predictions by using the specifications in the code (AISC-LRFD,EC4 and AIJ etc.) for the design of high-strength composite *** results indicate that the ultimate strength of steel and presence of concrete had significant influence on both the axial compressive load capacity and the ductile of the square steel tube.

关键词： square concrete-filled steel tubes high strength steel axial compression

A study of some Egyptian carbonate rocks for the building construction industry

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International Journal of Mining Science and Technology 2014年第4期24卷 467-470页

作者： Mahrous A.M. Ali hyung-sik Yang Mining and Petroleum Engineering Department Faculty of Engineering Alazhar University Energy and Resources Engineering Department College of Engineering Chonnam National University

A number of geotechnical analyses were carried out on selected carbonate rock samples from eight sites located in Egypt. This analysis was to assess the suitability of these rocks for building construction aggregate. The analyses included properties of uniaxial compressive strength, tensile strength, porosity, water absorption, and dynamic fragmentation. The success of building construction depends to a large extent on the availability of raw materials at affordable prices. Raw materials commonly used in the building industry include sands, gravels, clays and clay-derived products. Despite the widespread occurrence of carbonate rocks throughout Egypt, the low premium placed on their direct application in the building sector may be explained in two ways: firstly, the lack of awareness of the potential uses of carbonate rocks in the building construction industry(beyond the production of asbestos, ceiling boards, roof sheets and Portland cement); and secondly, the aesthetic application of carbonate rocks in the building construction depends mainly on their physical attributes, a knowledge of which is generally restricted to within the confines of research laboratories and industries. Thus this paper addresses the physical and mechanical characteristics of some Egyptian carbonate rocks, evaluating them for their suitability as building construction aggregates.

关键词： Carbonate rocks Building construction Raw materials Aggregates

Comparative fish community structure among different types of enclosures of estuarine environments

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Aquaculture and Fisheries 2022年第3期7卷 336-344页

作者： Sunwan hwang Keun-hyung Choi Marine Bio-Resources Research Unit KIOSTBusan49111Republic of Korea Department of Ocean Environmental Sciences Chung-Nam National UniversityDaejeon34134Republic of Korea

This study explores the differences of fish assemblages in three macrotidal estuaries of Man-gyeong River Estuary(MRE),Geum River Estuary(GRE),and Han River Esturay(HRE)with similar ranges of seasonal water temperature that are diked with different levels of disconnection from freshwater *** distribution of major species in the three estuaries could generally be grouped into three distinctive patterns based on their cumulative distribution with respect to the salinity *** MRE was geographically closer to the GRE than to the HRE,but the fish community of the MRE more closely resembled that of the *** freshness of the water inside the dike and the limit of coastal fish to the river may have led to this *** results provide clues to how enclosure patterns of estuarine waters could affect fish communities over a long-term *** addition,the information may provide guidance for how a fish community may return once environmental conditions are restored.

关键词： Fish community Diking Cumulative distribution Estuary Habitat connectivity

Characterization of smooth muscle, enteric nerve, interstitial cells of Cajal, and fibroblast-like cells in the gastric musculature of patients with diabetes mellitus

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World Journal of Gastroenterology 2016年第46期22卷 10131-10139页

作者： Kyung sik Park Kwang Bum Cho Il Seon hwang Jae hyung Park Byung Ik Jang Kyeong Ok Kim Sung Woo Jeon Eun Soo Kim Chang sik Park Joong Goo Kwon Department of Internal Medicine Keimyung University School of Medicine Department of Pathology Keimyung University School of Medicine Department of Physiology Keimyung University School of Medicine Department of Internal Medicine Youngnam University College of Medicine Department of Internal Medicine Kyungpook National University School of Medicine Department of Advanced Materials Convergence Korea Institute of Ceramic Engineering and Technology Department of Internal Medicine Catholic University of Daegu School of Medicine

AIM To investigate histologic abnormalities in the gastric smooth muscle of patients with diabetes mellitus(DM).METHODS Full-thickness gastric specimens were obtained from patients undergoing surgery for gastric cancer. H&E stain and Masson's Trichrome stain were performed to assess the degree of fibrosis. Immunohistochemical staining using various antibodies was also performed [antibodies against protein gene product 9.5(PGP9.5), neuronal nitric oxide synthase(n NOS), vasoactive intestinal peptide(VIP), neurokinin-1(NK1) receptor, c-Kit, and platelet-derived growth factor receptor-alpha,(PDGFRα)]. Immunofluorescent staining and evaluation with confocal microscopy were also *** Twenty-six controls and 35 diabetic patients(21 shortduration patients and 14 long-duration patients) were included. There were no significant differences in basic demographics between the two groups except in mean body mass index(BMI)(higher in the DM group). Proportions of moderate-to-severe intercellular fibrosis in the muscle layer were significantly higher in the DM group than in the control group(P < 0.01). On immunohistochemical staining, c-Kit- and PDGFRα-positive immunoreactivity were significantly decreased in the DM group compared with the control group(P < 0.05). There were no statistically significant differences in PGP9.5, n NOS, VIP, and neurokinin 1 expression. On immunofluorescent staining, cellularity of interstitial cells of Cajal(ICC) was observed to decrease with increasing duration of *** Our study suggests that increased intercellular fibrosis, loss of ICC, and loss of fibroblast-like cells are found in the smooth muscle of DM patients. These abnormalities may contribute to changes in gastric motor activity in patients with DM.

关键词： Diabetes mellitus Interstitial cells of Cajal Fibroblast-like cell Gastroparesis Enteric nerve system

Atomic layer deposition of an Al_2O_3 dielectric on ultrathin graphite by using electron beam irradiation

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Journal of Semiconductors 2012年第9期33卷 34-37页

作者：蒋然孟令国张锡健 hyung-Suk Jung Cheol Seong hwang School of Physics Shandong UniversityJinan 250100China Department of Materials Science and Engineering Seoul National UniversitySeoul 151-747Korea

Atomic layer deposition ofan Al2O3 dielectric on ultrathin graphite is studied in order to investigate the integration of a high k dielectric with graphite-based substrates. Electron beam irradiation on the graphite surface is followed by a standard atomic layer deposition ofAl2O3. Improvement of the Al2O3 layer deposition morphology was observed when using this radiation exposure on graphite. This result may be attributed to the amorphous change of the graphite layers during electron beam irradiation.

关键词： Al2O3 high k atomic layer deposition graphene