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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

Mechanical properties of graphene oxide?silk fibroin bionanofilms via nanoindentation experiments and finite element analysis

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Friction 2022年第2期10卷 282-295页

作者： Hyeonho CHO Joonho LEE Hyundo hwang Woonbong hwang Jin-Gyun KIM Sunghan KIM School of Mechanical Engineering Chung-Ang UniversitySeoul 06974Republic of Korea Department of Mechanical Engineering(Integrated Engineering) Kyung Hee UniversityGyeonggi 17104Republic of Korea Department of Mechanical Engineering POSTECHPohang 37673Republic of Korea Department of Robotics&Mechatronics.Korea Institute of Machinery&Materials Daejeon 34103Republic of Korea

Understanding the mechanical properties of bionanofilms is important in terms of identifying their *** primary focus of this study is to examine the effect of water vapor annealed silk fibroin on the indentation modulus and hardness of graphene oxide-silk fibroin(GO-SF)bionanofilms through nanoindentation experiments and finite element analysis(FEA).The GO-SF bionanofilms were fabricated using the layer-by-layer *** water vapor annealing process was employed to enhance the interfacial properties between the GO and SF layers,and the mechanical properties of the GO-SF bionanofilms were found to be affected by this *** employing water vapor annealing,the indentation modulus and hardness of the GO-SF bionanofilms can be ***,the FEA models of the GO-SF bionanofilms were developed to simulate the details of the mechanical behaviors of the GO-SF *** difference in the stress and strain distribution inside the GO-SF bionanofilms before and after annealing was *** addition,the load-displacement curves that were obtained by the developed FEA model conformed well with the results from the nanoindentation *** summary,this study presents the mechanism of improving the indentation modulus and hardness of the GO-SF bionanofilms through the water vapor annealing process,which is established with the FEA simulation models.

关键词： graphene oxide silk fibroin layer-by-layer(LbL) nanoindentation finite element analysis(FEA)

Small Zeros of Additive Forms in Several Variables

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Acta Mathematica Sinica,English Series 1998年第1期14卷 57-66页

作者： J. S. hwang Institute of Mathematics Academia Sinica Taipei Taiwan 11529 China

Let f（X） be an additive form defined by f（X）=f（x1. x2,…,xs）=σ1α1x1k+σα2x2k+…+σsαsxsk, where αo≠0 is integer, i=1, 2,…, s. In 1979, Schmidt proved that if ε>0 then there is a large constant C（k, ε） such that for s≥C（k, ε） the equation f（X）=0 has a nontrivial integer solution in σ1. σ2,…σs, x1, x2…,xs satisfying σi=±1 and |xi|≤Aε, i=1, 2.…,s where A=max|ai|. Schmidt did not estimate this constant C（k. ε） since it would be extremely large. In this paper, we prove the following result: Theorem 1 If log A≤1/ε,then C（k,ε）≤max （2/ε,20）; if log A>1/ε,A is sufficiently larye and 1/2A≤5≤|ai|≤A,i=1. 2,…, s, then C（k,ε）≤c1c2p and if the last condition is omitted, then C（k. ε）≤[4/ε]c1c2,where c1={2k+1 for≤k≤11 [5k2log k] for k≥12, c2=100c1k22k+c12 and p=2[log 2c1/ε]. We note that the inequality in the first case is sharp but not in the second case.

关键词： Additive form Subset sums Small zeros

Enhancement of GAO's Multiparty Quantum Secret Sharing

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Communications in Theoretical Physics 2011年第7期56卷 79-82页

作者： Cheng-Chieh hwang Tzonelih hwang Chuan-Ming Li Department of Computer Science and Information Engineering National Cheng Kung University Department of Information Management Shu-Zen College of Medicine and Management

A multiparty quantum secret sharing (MQSS) protocol with two-photon three-dimensional Bell states was proposed by Gao [Commun. Theor. Phys. 52 (2009) 421] recently. This study points out that the performance of Gao's protocol can be much improved by using the technique of decoy single photons and carefully modifying the protocol to remove some unnecessary unitary operations, devices, and transmissions.

关键词： quantum secret sharing Greenberger-Horne-Zeilinger state

Effect of reduction in area per pass on strain distribution and microstructure during caliber rolling in twinning-induced plasticity steel

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Journal of Iron and Steel Research International 2020年第1期27卷 62-74页

作者： Joong-ki hwang Sung Jin Kim School of Mechanical Engineering Tongmyong UniversityBusan 48520Republic of Korea Department of Advanced Materials Engineering Sunchon National UniversitySuncheon 57922Republic of Korea

The effects of reduction in area(RA)per pass during caliber rolling on microstructure and strain distribution of twinninginduced plasticity steel have been investigated to find solutions to make a more homogeneous material along the radial direction for wire rod *** steel wires subjected to an average RA per pass of 2.5%(skin pass caliber rolling)and 10.0%(conventional caliber rolling)were *** skin pass caliber-rolled wire was characterized as a duplex fiber texture of majorand minor.and the textures were almost same at/between center and surface area,which is totally different from those of conventional caliber rolling and wire *** skin pass caliber rolling led to more homogeneous microstructure and mechanical properties along the radial direction in comparison with the conventional caliber rolling and wire drawing due to the more homogeneous Hall-Petch hardening,dislocation hardening,and texture behavior with area,resulting in higher formability.

关键词： Twinning-induced plasticity steel Caliber rolling Deformation twin Reduction in area Skin pass

Review on Tidal Energy Technologies and Research Subjects

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China Ocean Engineering 2020年第1期34卷 137-150页

作者： Chul Hee JO Su Jin hwang Department of Naval Architecture and Ocean Engineering Inha University

Tidal current power is one of the promising and reliable renewable energies with the advantage of continuous and predictable resource. It can make stable electricity regardless of weather conditions or seasons all year around. The required technologies for tidal current power in the ocean have been developed for years and now recognized that it could be commercialized after intensive field tests and successful demonstrations. There are several tidal farm development projects in the world, such as the MeyGen project in UK with its commercialization at hand. However, various research subjects in the tidal current energy field are seeking improvements and industrialization of tidal current power in terms of economy and technical reliability. This paper introduces the resource assessment procedure of tidal energy that has been applied in Korea coastal regions. The key research subjects for tidal current power together with the interaction effect of multi-arrangement is described. Also, this paper is to introduce the research output of each subject such as turbine design, experimental validation, turbine interaction and wake, multi-array module, FSI (fluid-structure interaction), and duct application.

关键词： tidal current power resource assessment turbine design experimental validation turbine interaction multi arrangement FSI(fluid-structure interaction)

Lp Boundedness of Fourier Integral Operators in the Class S1,0

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Acta Mathematica Sinica,English Series 2023年第1期39卷 37-98页

作者： Ing-Lung hwang Department of Mathematics “National Chung Cheng University of Taiwan”

We prove the following properties:(1) Let a ∈ Λ1,0,k,k’m0(Rn×Rn) with m0=-1|1/p-1/2|(n-1),n≥2(1 n/p,k’> 0;2≤p≤∞,k>n/2,k’>0 respectively).Suppose the phase function S is positively homogeneous in ξ-variables,non-degenerate and satisfies certain *** the Fourier integral operator T is *** the method of(1),we can obtain the Lp-boundedness of the Fourier integral operator if(2) the symbol a ∈ Λ1,δ,k,k’m0, 0≤δ≤1,with m0,k,k’ and S given as in(1).Also,the method of(1) gives:(3) a ∈ Λ1,δ,k,k’0,0≤δ<1 and k,k’given as in(1),then the Lp-boundedness of the pseudo-differential operators holds,1

关键词： Fourier integral operator Lp-boundedness

A Method for Detecting Non-Mask Wearers Based on Regression Analysis

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Computers, Materials & Continua 2022年第9期72卷 4411-4431页

作者： Dokyung hwang Hyeonmin Ro Naejoung Kwak Jinsang hwang Dongju Kim POSTECH Institute of Artificial Intelligence Pohang24257Korea Department of Information Security at Pai Chai University Daejeon35345Korea Department of Safety and Emergency Management at Kyungwoon University Gumi39160Korea

A novel practical and universal method of mask-wearing detection has been proposed to prevent viral respiratory *** proposed method quickly and accurately detects mask and facial regions using welltrained You Only Look Once(YOLO)detector,then applies image coordinates of the detected bounding box(bbox).First,the data that is used to train our model is collected under various circumstances such as light disturbances,distances,time variations,and different climate *** also contains various mask types to detect in general and universal application of the *** detect mask-wearing status,it is important to detect facial and mask region accurately and we created our own dataset by taking picture of ***,the Convolutional Neural Network(CNN)model is trained with both our own dataset and open dataset to detect under heavy foot-traffic(Indoors).To make the model robust and reliable in various environment and situations,we collected various sample data in different *** through the experiment,we found out that there is a particular gradient according to the mask-wearing *** proposed method searches the point where the distance between the gradient for each state and the coordinate information of the detected object is the *** it carry out the classification of mask-wearing status of detected ***,we defined and classified three different mask-wearing states according to the mask’s position(With mask,Wear a mask around chin and Without mask).The gradient according to the mask-wearing status,is analyzed through linear *** regression interpretation is based on coordinate information of mask-wearing status and the sample data collected in simulated environment that considering distances between objects and the camera in the World Coordinate *** the experiments,we found out that linear regression analysis is more suitable than logistic regression analysis for classification of people wea

关键词： Automatic quarantine process detection of improper mask wearers facial image coordinates convolution neural network

Experimental Investigation of Aerodynamic Performance due to Blade Tip Clearance in a Gas Turbine Rotor Cascade

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Journal of Thermal Science 2022年第1期31卷 173-178页

作者： CHUNG Jinmoo BAEK Seungchan hwang Wontae Department of Mechanical Engineering Seoul National UniversitySeoul 08826Republic of Korea Institute of Advanced Machines and Design Seoul National UniversitySeoul 08826Republic of Korea Institute of Engineering Research Seoul National UniversitySeoul 08826Republic of Korea

This study examines how the complex flow structure within a gas turbine rotor affects aerodynamic loss. An unshrouded linear turbine cascade was built, and velocity and pressure fields were measured using a 5-hole probe. In order to elucidate the effect of tip clearance, the overall aerodynamic loss was evaluated by varying the tip clearance and examining the total pressure field for each case. The tip clearance was varied from 0% to 4.2% of blade span and the chord length based Reynolds number was fixed at 2×10^(5). For the case without tip clearance, a wake downstream of the blade trailing edge is observed, along with hub and tip passage vortices. These flow structures result in profile loss at the center of the blade span, and passage vortex related losses towards the hub and tip. As the tip clearance increases, a tip leakage vortex is formed, and it becomes stronger and eventually alters the tip passage vortex. Because of the interference of the secondary tip leakage flow with the main flow, the streamwise velocity decreases while the total pressure loss increases significantly by tenfold in the last 30% blade span region towards the tip for the 4.2% tip clearance case. It was additionally observed that the overall aerodynamic loss increases linearly with tip clearance.

关键词： gas turbine turbine cascade aerodynamic loss tip clearance tip leakage