Analysis of South Korea's Direct Investment in China

Xiaohong Zhan Jungseok Research Institute of International Logis 2004 JOURNAL OF INTERNATIONAL LOGISTICS AND TRADE Vol.2 No.2

Using a dynamic perspective this article examines, the general situation of the development of south Korean direct investment in China since 1992, when the two countries established diplomatic relations. It probes many characteristics of South Korean direct investment in China; its late start yet rapid rise; the smaller average value of Korean project investments; the accelerated process of localization by large South Korean enterprises in China; the diversified industrial distribution; and the wide-ranging geographical distribution. It analyses the reasons for the rapid increase in South Korean investment in China: the use of china's low-priced production factors, the direct entry of South Korean enterprises into the Chinese market, and the stable investment environment with fewer labor disputes that China provides. Finally, this article also proves that south Korean enterprises have achieved satisfactory results from their direct investment in China.

Numerical simulation of resistance welding of solar cell using a thermal-electrical-mechanical coupled model

Xiaohong Zhan,Qi Zhang,Zhenxin Zhu,Yanhong Wei 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.1

A thermal-electrical-mechanical coupled model was established to simulate the Parallel-gap resistance welding (PGRW) process between the Germanium-based solar cell and the silver interconnector. The simulated results showed that the peak temperature during PGRW is lower than the melting temperature of the base material. It is indicated that the connection mechanism of PGRW was mainly the interdiffusion and recrystallization due to pressure of electrode and the resistance heat. A detailed calculation method of current was proposed using semi-layered resistance model and layered resistance model. By comparing these models, it was found that the layered resistance model was more accurate to calculate the current value. The maximum residual stress was generated within the region under the welding electrode, while the maximum deformation was generated on the edge of the interconnector. The current variation trend predicated by the simulation results is in good agreement with the results obtained by the experiments.

한국의 對중국 직접투자 현황 분석

Zhan Xiaohong 인하대학교 정석물류통상연구원 2004 인하대학교 정석물류통상연구원 학술대회 Vol.2004 No.11

韩国对华直接投资状况的分析

詹小洪(Zhan Xiaohong) 인하대학교 정석물류통상연구원 2004 인하대학교 정석물류통상연구원 학술대회 Vol.2004 No.11

Synthesis and characterization of silk fibroin-bioactive glass hybrid xerogels

Wu, Xiaohong,Yan, Fuhua,Liu, Wei,Zhan, Hongbing,Yang, Wenrong Techno-Press 2014 Biomaterials and biomedical engineering Vol.1 No.2

This study aimed to develop a novel bioactive hybrid xerogel consisting of silk fibroin /$SiO_2-CaO-P_2O_5$ by sol-gel process at room temperature. Scanning electron microscopy (SEM), FT-IR Spectroscopy, pore measurement, mechanical property testing, in vitro bioactivity test and cytotoxicity assay were performed to characterize the xerogel for bone tissue engineering application. We have found that the xerogel possessed excellent pore structures and mechanical property. Once immersed in a simulated fluid (SBF), the xerogel exhibited profound bioactivity by inducing hydroxyapatite layers on its surfaces. The cell toxicity study also demonstrated that there was little toxic to MC3T3-E1 cells. These results indicate that silk fibroin /$SiO_2-CaO-P_2O_5$ hybrid xerogel potentially could be used as a bone tissue engineering material.

Synthesis and characterization of silk fibroin-bioactive glass hybrid xerogels

Wu, Xiaohong,Yan, Fuhua,Liu, Wei,Zhan, Hongbing,Yang, Wenrong Techno-Press 2014 Biomaterials and Biomechanics in Bioengineering Vol.1 No.2

This study aimed to develop a novel bioactive hybrid xerogel consisting of silk fibroin /$SiO_2-CaO-P_2O_5$ by sol-gel process at room temperature. Scanning electron microscopy (SEM), FT-IR Spectroscopy, pore measurement, mechanical property testing, in vitro bioactivity test and cytotoxicity assay were performed to characterize the xerogel for bone tissue engineering application. We have found that the xerogel possessed excellent pore structures and mechanical property. Once immersed in a simulated fluid (SBF), the xerogel exhibited profound bioactivity by inducing hydroxyapatite layers on its surfaces. The cell toxicity study also demonstrated that there was little toxic to MC3T3-E1 cells. These results indicate that silk fibroin /$SiO_2-CaO-P_2O_5$ hybrid xerogel potentially could be used as a bone tissue engineering material.

Influence of Laser Power on Grain Size and Tensile Strength of 5A90 Al–Li Alloy T-joint Fabricated by Dual Laser-Beam Bilateral Synchronous Welding

Shuai Chen,Xiaohong Zhan,Yanqiu Zhao,Youfa Wu,Dongtao Liu 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

Dual laser-beam bilateral synchronous welding is introduced to produce the 2.5 mm thick 5A90 Al–Li alloy T-joint. Thegrain morphology and grain size of weld metal (WM) in the T-joint are analyzed and calculated. The tensile experiment,scanning electron microscopy and energy disperse spectroscopy are respectively employed to study the tensile strength,fracture morphology and chemical composition of the T-joint. The results reveal that when the laser power is increased from2500 to 3000 W, the grain sizes of fine-grained layers and columnar dendrites near the fusion line are significantly reduced. Conversely, that of equiaxed dendrites at the WM center is not sensitive to the variety of laser power. Moreover, the degreeof elemental segregation in WM near the fusion line is also aggravated with the increasing of the laser power. The tensilestrength of the T-joint with the laser power of 2500 W is significantly higher than that with the laser power of 3000 W. Thetensile fracture locations are occurred in the weld toe with obvious pores, shear dimples and tear ridges, which are the typicalcharacteristics of ductile fracture. Besides, the chemical compositions of the second phase particles in the WM are moresensitive to than the variation of laser power compared with that of the matrix.

Research on the Microstructure Characteristic and Tensile Property of Laser‑MIG Hybrid Welded Joint for 5A06 Aluminum Alloy

Yanqiu Zhao,Xiaohong Zhan,Qiyu Gao,Shuai Chen,Yue Kang 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.3

Laser-metal inter gas (MIG) hybrid welding technique provides higher overall productivity over the traditional fusionwelding processes for joining medium-thick aluminum alloy. In this paper, laser-MIG hybrid welding experiment was performedby the TruDisk 12003 Laser and KUKA robot. The second fusion line, the laser-dominated region and laser-MIGhybrid-dominated region were introduced to this study to discuss the microstructure distribution. A three-dimensionalfinite element model was established by MSC. Marc to study the thermal field distribution of laser-MIG hybrid weldingprocess. It found that the temperature in the laser-MIG hybrid-dominated region was much higher than the laser-dominatedregion. The formation of the second fusion line in the welded joint is mainly owing to the different heat effect of laser-archybrid-dominated region and laser-dominated region. The crystalline size of equiaxed dendrite grains in the laser-MIGhybrid-dominated region is finer than the laser-dominated region. In addition, the tensile property was measured to dissectthe failure mechanism of the laser-MIG hybrid welding joints. The element content in fractured surface at the position ofdimple and pore wall were comprehensively analyzed. The element content of Mg and O in pore wall are higher than dimple. In the solidification process, the growth of equiaxed dendrite grains is in part hindered by the existence of coarse pores inthe laser-MIG hybrid-dominated region.

Wear Resistance of Different Bionic Structure Manufactured by Laser Cladding on Ti6Al4V

Mengyao Wu,Xiaohong Zhan,Hengchang Bu,Lijun Liu,Yuanzeng Song,Yaping Li 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

In this study, the laser cladding system with an IPG YLS-6000 fber laser was used, and the WC–Ti6Al4V powder reinforcedcomposite coatings on Ti6Al4V titanium alloy with various bionic structures were innovatively fabricated. The microstructures and surface damage behavior of the coatings were characterized by scanning electron microscopy, energy dispersivespectroscopy, and X-ray difraction. Additionally, the wear resistance of diferent bionic structures was evaluated, which hadnot been comprehensively explored in the published literature. The results indicated that the un-melted WC particles in thecoatings act as a hard reinforcement, avoiding serious wear of the coating. In addition, the hard coatings exhibit excellentdeformation resistance and the soft substrate cushion the shear stress. So when the “Ratio”, which refers to the laser cladding area to sample area, is between 0.25 and 0.3, the sample has the highest wear resistance. Furthermore, the “Dot+Line”bionic structure has the best wear resistance compared with other structures. The separated line units and the addition of dotunits can improve the stress concentration state of bionic structure are conducive to release the stress to the substrate underthe cladding layer.

Analysis of Elements Non-Uniform Distribution of FeCoCrNi High-Entropy Alloy Coatings on Ti–6Al–4V Surface by Laser Cladding

Shuyao Duan,Xiaohong Zhan,Mengyao Wu,Hengchang Bu,Qiyu Gao 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.3

The evolution of element distribution during laser cladding involves two dynamic behaviors, i.e., liquid molten pool flow andFeCoCrNi high-entropy alloy (HEA) coatings solidification. However, it is quite difficult to characterize element distributionduring the flow of the liquid molten pool rigorously. The current investigation conducted the optical microscopy, scanningelectron microscopy, X-ray diffraction analysis and energy dispersive spectrometer to study the dilution, phase composition,microstructure of the FeCoCrNi coatings. The flow field was simulated to uncover the dynamic change mechanism of themolten pool and explain the experimental results. The results indicated that the coating is substantially composed of FCCand BCC solid solution with a typical dendrite microstructure. Gray Laves phase-(Ni, Co)2Ti and a small number of whitedot particles, Fe–Cr phase, are dispersed in the inter-dendritic region. The HEA atoms (Fe, Co, Cr, Ni) gradually aggregatefrom the center to the side at the coating boundary region, while the Ti atom is the opposite. The Marangoni flow inflectionpoint at the molten pool boundary will cause HEA atoms to aggregate. On the contrary, Ti atom enters the molten poolfrom the bottom with the heat buoyance flow and then migrates to the boundary along with the Marangoni flow. Therefore,the content of Ti in the coating boundary decreases. The Marangoni flow, heat buoyance flow, and recoil pressure flow areinterwoven in the middle region of the coating, resulting in a more uniform element distribution than the boundary region.