Methylene Blue Removal by Graphene Oxide/Alginate Gel Beads

Xianjun Liu,Baochen Cui,Shuzhi Liu,Qing Ma 한국섬유공학회 2019 Fibers and polymers Vol.20 No.8

Methylene blue (MB) adsorption capacity in water matrices depends highly on the properties of each componentof the adsorption systems. The most important one of these is the physicochemical properties of the adsorbent. A compositegel bead was prepared from graphene oxide (GO) and sodium alginate (SA) through a combination of freeze-drying andcross-linking with calcium chloride. Fundamental adsorption behavior of the gel beads for removal of MB from aqueoussolutions has been investigated. The pH had mild influence on the adsorption, while adsorption increased as the adsorbentdosage, initial concentration, and contact time increased. The kinetic adsorption fitted the pseudo second-order and intraparticlediffusion models. The isotherm data followed the Langmuir and Freundlich models. The maximum adsorptioncapacity from the Langmuir isotherm equation reached 357.14 mg/g. The results of the thermodynamic investigationsindicated that the adsorption reactions were spontaneous (ΔG<0, -13.79 kJ/mol), exothermic (ΔH<0, -46.7 kJ/mol). Inaddition, the adsorption capacity of the regenerated gel beads has little loss until four cycles.

Impact of COVID-19 on Korea-China Import and Export Trade and Countermeasures

Do-Joon Park(Do-Joon Park),Shuzhi Liu(Shuzhi Liu) The International Academy of Global Business and T 2022 The International Academy of Global Business and T Vol.18 No.6

Purpose - This paper empirically investigates the changes and trends in export and import trade between Korea and China since 2000, especially after the establishment of Korea-China FTA and since the outbreak of COVID-19. This paper uses empirical analysis to determine the f uture t rade t ypes and t rends of import/ export trade between Korea and China and estimates the impact on import/export trade between Korea and China in the post-epidemic era. Design/Methodology/Approach - This paper first reviews the theories related to regional economic integration, sorts out the process of Korea-China FTA, and summarizes the changes and trends in import and export trade since COVID-19; second, it analyzes the current situation of bilateral trade between Korea and China using quantitative analysis, and investigates the specific impact of COVID-19 on Korea-China import and export trade using empirical analysis; finally, it summarizes the above studies, a conclusion is drawn, and policy recommendations are made to better utilize the challenges brought by COVID-19 to effectively address the problems that may be encountered in Korea-China trade and to promote the development of bilateral trade between the two countries. Findings - The global spread of the epidemic in Korea and China has led to the shutdown of both domestic and foreign operations, resulting in a foreign trade cliff effect in the short to medium term; the trade creation effect inspired by the international system dividend is no longer available in China in 2020, and the trade in goods is diminishing at the margin; the trade suppression effect is generated by the rise of international trade protectionism. The epidemic has led to a large upstream supply shortage pressure on the electronic information industry and the automobile manufacturing industry, and a large downstream demand shortage pressure on the energy industry and the electronic information industry. Research Implications - The establishment of Korea-China FTA will significantly promote bilateral trade between the two countries, change the trade and industrial structure of the two countries, and help to promote the development of the FTA strategy of the two countries; the outbreak of COVID-19 has changed the trade pattern and type, and the import and export of related epidemic prevention products as a new trade growth point and strengthened the trade market relationship between Korea and China.

A Study on the Economic Effects of U.S. Export Controls on Semiconductors to China

박도준,Shuzhi Liu 한국무역연구원 2023 무역연구 Vol.19 No.1

Purpose – This study addresses the development of China’s semiconductor industry in the context of the U.S.-China trade conflict, and analyzes the impact on other industries. Design/Methodology/Approach – Based on the multi-regional input-output table industry splitting method, the electrical and electronic equipment manufacturing industry in the Asian Development Bank’s multi-regional input-output table (ADB-MRIO, 2019) is split into semiconductor and non-semiconductor industries, and the impact of U.S. export controls on China’s semiconductor exports on domestic and foreign economies is simulated and analyzed using the hypothesis extraction and hypothesis expansion methods. Findings – The United States has suffered more than China from US export controls on semiconductors to China, and the impact of U.S. export controls on U.S. GDP decreasing by at most 0.0124‰, and China’s GDP decreasing by at most 0.00089‰. Since Japan, Korea, and European countries have become China’s semiconductor import substitutes, they all benefit from U.S. export controls on China. Second, the most affected industries in China are the chemical products, metal products, wholesale, financial, and non-semiconductor industries in the electrical and electronic equipment manufacturing industry. Research Implications – China should adopt coping strategies such as deepening international exchanges, enhancing communication between China and the U.S., and strengthening its scientific and technological strength.

A Modular Designed Bolt Tightening Shaft Based on Adaptive Fuzzy Backstepping Control

Sibang Liu,Shuzhi Sam Ge,Zhongliang Tang 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.4

This paper presents a modular designed autonomous bolt tightening shaft system with an adaptive fuzzybackstepping control approach developed for it. The bolt tightening shaft is designed for the autonomous bolttightening operation, which has huge potential for industry application. Due to the inherent nonlinear and uncertainproperties, the bolt tightening shaft and the bolt tightening process are mathematically modeled as an uncertain strictfeedback system. With the adaptive backstepping and approximation property of fuzzy logic system, the controlleris recursively designed. Based on the Lyapunov stability theorem, all signals in the closed-loop system are proved tobe uniformly ultimately bounded and the torque tracking error exponentially converges to a small residue. And theeffectiveness and performance of the proposed autonomous system are verified by the simulation and experimentresults on the bolt tightening shaft system.

A novel lattice structure topology optimization method with extreme anisotropic lattice properties

Zhang Chenghu,Liu Jikai,Yuan Zhiling,Xu Shuzhi,Zou Bin,Li Lei,Ma Yongsheng 한국CDE학회 2021 Journal of computational design and engineering Vol.8 No.5

This research presents a lattice structure topology optimization (LSTO) method that significantly expands the design space by creating a novel candidate lattice that assesses an extremely large range of effective material properties. About the details, topology optimization is employed to design lattices with extreme directional tensile or shear properties subject to different volume fraction limits and the optimized lattices are categorized into groups according to their dominating properties. The novel candidate lattice is developed by combining the optimized elementary lattices, by picking up one from each group, and then parametrized with the elementary lattice relative densities. In this way, the LSTO design space is greatly expanded for the ever increased accessible material property range. Moreover, the effective material constitutive model of the candidate lattice subject to different elementary lattice combinations is pre-established so as to eliminate the tedious in-process repetitive homogenization. Finally, a few numerical examples and experiments are explored to validate the effectiveness of the proposed method. The superiority of the proposed method is proved through comparing with a few existing LSTO methods. The options of concurrent structural topology and lattice optimization are also explored for further enhancement of the mechanical performance.

A Study on the Optimal Reconfigurable Intelligent Surfaces Placement

Jiaqi Li(이가기),Shuzhi Liu(유서지),Seung-Hoon Hwang(황승훈) 한국통신학회 2022 한국통신학회 학술대회논문집 Vol.2022 No.11

Magnetoresistance Characteristics of Magnetorheological Gel under a Magnetic Field

Yu, Miao,Ju, Benxiang,Fu, Jie,Liu, Shuzhi,Choi, Seung-Bok American Chemical Society 2014 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.53 No.12

<P>A kind of magnetoresistance material was prepared, named as magnetorheological gel (MRG). The MRG samples were fabricated by dispersing carbonyl iron particles (CIP) into the polyurethane gel, and several experimental devices were prepared to investigate the magnetoresistance characteristics of MRG. The magnetoresistance characteristic was systematically tested and the influence of the magnetic field was analyzed. It is found that the resistance value of MRG with the CIP content of 70 wt % can be decreased from 7.56 to 2.44 MΩ with increasing of magnetic field from 0.1 T to 1 T. The experimental results have also proved that CIP content and the composition of matrix have a greater impact on the magnetoresistance characteristics. Because of the interaction between the magnetic force of CIP and motion resistance under a magnetic field, the obvious hysteresis phenomenon was observed and recorded. Lastly, it was observed that the magnetoresistance can be changed reversibly by controlling the magnetic field.</P>

Enabling technologies for AI empowered 6G massive radio access networks

Md. Shahjalal,Woojun Kim,Waqas Khalid,Seokjae Moon,Murad Khan,ShuZhi Liu,Suhyeon Lim,Eunjin Kim,Deok-Won Yun,Joohyun Lee,Won-Cheol Lee,Seung-Hoon Hwang,Dongkyun Kim,Jang-Won Lee,Heejung Yu,Youngchul S 한국통신학회 2023 ICT Express Vol.9 No.3

Predictably, the upcoming six generation (6G) networks demand ultra-massive interconnectivity comprising densely congested sustainable small-to-tiny networks. The conventional radio access network (RAN) will be redesigned to provide the necessary intelligence in all areas to meet required network flexibility, full coverage, and massive access. In this respect, this paper focuses on intelligent massive RAN (mRAN) architecture and key technologies fulfilling the requirements. Particularly, we investigate potential AI algorithms for network and resource management issues in 6G mRAN. Furthermore, we summarize the research issues in edge technologies and physical layer intelligence on 6G network architecture.