An Empirical Study of Technology Diffusion and International Trade in Korea: Using Patent Application Data

Weifeng Zhu,Keunyeob Oh 서울대학교 경제연구소 2009 經濟論集 Vol.48 No.3

International trade is an important conduit for international technology diffusion. Considering the endogenous growth theory, a rapid increase of foreign patent application, and international trade in Korea, it seems meaningful to study the role of international trade in the technology diffusion from foreign countries to Korea. This paper investigates the relationship between the trade and technology diffusion by using Korean patent data and trade data. We found that the international trade of Korea with foreign countries was very significant variable.

An Empirical Study of Technology Diffusion and International Trade in Korea : Using Patent Application Data

Zhu, Weifeng,Oh, Keunyeob 서울大學校經濟硏究所 2009 經濟論集 Vol.48 No.2·3

International trade is an important conduit for international technology diffusion. Considering the endogenous growth theory, a rapid increase of foreign patent application, and international trade in Korea, it seems meaningful to study the role of international trade in the technology diffusion from foreign countries to Korea. This paper investigates the relationship between the trade and technology diffusion by using Korean patent data and trade data. We found that the international trade of Korea with foreign countries was very significant variable.

Identification and confirmation of 14-3-3 ζ as a novel target of ginsenosides in brain tissues

Feiyan Chen,Lin Chen,Weifeng Liang,Zhengguang Zhang,Jiao Li,Wan Zheng,Zhu Zhu,Jiapeng Zhu,Yunan Zhao 고려인삼학회 2021 Journal of Ginseng Research Vol.45 No.4

Background: Ginseng can help regulate brain excitability, promote learning and memory, and resist cerebral ischemia in the central nervous system. Ginsenosides are the major effective compounds of Ginseng, but their protein targets in the brain have not been determined. Methods: We screened proteins that interact with the main components of ginseng (ginsenosides) by affinity chromatography and identified the 14-3-3 ζ protein as a potential target of ginsenosides in brain tissues. Results: Biolayer interferometry (BLI) analysis showed that 20(S)-protopanaxadiol (PPD), a ginseng saponin metabolite, exhibited the highest direct interaction to the 14-3-3 ζ protein. Subsequently, BLI kinetics analysis and isothermal titration calorimetry (ITC) assay showed that PPD specifically bound to the 14-3-3 ζ protein. The cocrystal structure of the 14-3-3 ζ protein-PPD complex showed that the main interactions occurred between the residues R56, R127, and Y128 of the 14-3-3 ζ protein and a portion of PPD. Moreover, mutating any of the above residues resulted in a significant decrease of affinity between PPD and the 14-3-3 ζ protein. Conclusion: Our results indicate the 14-3-3 ζ protein is the target of PPD, a ginsenoside metabolite. Crystallographic and mutagenesis studies suggest a direct interaction between PPD and the 14-3-3 ζ protein. This finding can help in the development of small-molecular compounds that bind to the 14-3-3 ζ protein on the basis of the structure of dammarane-type triterpenoid.

Phase-Shift Triple Full-Bridge ZVZCS Converter with All Soft Switched Devices

Zhu, Junjie,Qian, Qinsong,Lu, Shengli,Sun, Weifeng The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6

This paper proposes a Phase-Shift Triple Full-Bridge (PSTB) Zero-Voltage Zero-Current-Switching (ZVZCS) converter with a high switching frequency and high efficiency. In the proposed converter, all three bridge legs are shared leading-legs, and all three transformers work in the Discontinuous Conduction Mode (DCM). Thus, all of the switches and diodes in the PSTB ZVZCS can be soft switched. Moreover, since all of the transformers can pass energy from the primary-side to the secondary-side when their primary-side currents are not zero, there is no circulating current. As a result, the PSTB ZVZCS converter can achieve a high efficiency at high operating frequencies. A theoretical analysis and the characteristics of the proposed converter are presented and verified on a 1MHz 200~300V/24V 1.2kW hardware prototype. The proposed converter can reach a peak efficiency of 96.6%.

Research on a new type of squirt gun for cleaning

Jinmu ZHU,Xinping LONG,Weifeng WU,Hao YAO 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.10

A new type of squirt gun, which is similar to a jet pump and can better induce formation of cavitating water jet, is presented. The scheme of design of this new squirt gun is discussed. An investigation of effect of different area ratio, length of throat pipe, standoff distance, nozzle type, and suction air amount on decontamination ability was made by experiments. This new squirt gun is experimentally compared with conventional one. Test data indicate that under the same operating condition the new type of squirt gun have the advantages of better decontamination ability, lower energy consumption and less water consuming over conventional one. The optimum operating parameters of this new device are put forward on the basis of test results.

Traffic speed mapping with cellular network signaling data by FOSS4G

Wang Weifeng,Zhu Kemin,Liu Junli,Hu Jinghao,Raganvan Venkatesh,Xu Jiang,Song Xianfeng 대한공간정보학회 2022 Spatial Information Research Vol.30 No.1

Mapping traffic speed on road networks is crucial for urban traffic management and the development of intelligent transportation systems. Traditionally, information regarding traffic speed can be obtained from locationfixed sensors, such as loop detectors and cameras; however, these methods are limited to major road crosses. Recently, a considerable attention has been paid to utilizing vehicles with mobile phones as probes for collecting traffic information. This study proposes an open-source GIS approach to map traffic speeds in a road network. First, public service vehicles (PSVs) were identified from cellular network signaling data by measuring the similarity between cell-ID trajectories and bus routes. Then, the cell-ID trajectories of PSVs were refined into high-quality spatiotemporal trajectories, and projected onto the road network via heuristic global optimization. Finally, hourly traffic speed maps were computed by weighing the speeds of the PSVs in the road network. The approach was implemented using free and open source software for geospatial mapping stacks of toolkits (Python, TimescaleDB/PostGIS, Pandas/Pygmo2, and Matplotlib/Seaborn); this application demonstrated good results using cellular network signaling data and GPS trajectories collected in Huilongguan district, Beijing, China. Moreover, this demonstration illustrates that probe mobile monitoring is emerging as a critical technology for traffic monitoring supplements, which can help develop a comprehensive view of the roads and reduce the cost of monitoring a large area.

Phase-Shift Triple Full-Bridge ZVZCS Converter with All Soft Switched Devices

Junjie Zhu,Qinsong Qian,Shengli Lu,Weifeng Sun 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6

This paper proposes a Phase-Shift Triple Full-Bridge (PSTB) Zero-Voltage Zero-Current-Switching (ZVZCS) converter with a high switching frequency and high efficiency. In the proposed converter, all three bridge legs are shared leading-legs, and all three transformers work in the Discontinuous Conduction Mode (DCM). Thus, all of the switches and diodes in the PSTB ZVZCS can be soft switched. Moreover, since all of the transformers can pass energy from the primary-side to the secondary- side when their primary-side currents are not zero, there is no circulating current. As a result, the PSTB ZVZCS converter can achieve a high efficiency at high operating frequencies. A theoretical analysis and the characteristics of the proposed converter are presented and verified on a 1MHz 200~300V/24V 1.2kW hardware prototype. The proposed converter can reach a peak efficiency of 96.6%.

Traffic speed mapping with cellular network signaling data by FOSS4G

Wang Weifeng,Zhu Kemin,Liu Junli,Hu Jinghao,Raganvan Venkatesh,Xu Jiang,Song Xianfeng 대한공간정보학회 2022 Spatial Information Research Vol.30 No.2

Mapping traffic speed on road networks is crucial for urban traffic management and the development of intelligent transportation systems. Traditionally, information regarding traffic speed can be obtained from locationfixed sensors, such as loop detectors and cameras; however, these methods are limited to major road crosses. Recently, a considerable attention has been paid to utilizing vehicles with mobile phones as probes for collecting traffic information. This study proposes an open-source GIS approach to map traffic speeds in a road network. First, public service vehicles (PSVs) were identified from cellular network signaling data by measuring the similarity between cell-ID trajectories and bus routes. Then, the cell-ID trajectories of PSVs were refined into high-quality spatiotemporal trajectories, and projected onto the road network via heuristic global optimization. Finally, hourly traffic speed maps were computed by weighing the speeds of the PSVs in the road network. The approach was implemented using free and open source software for geospatial mapping stacks of toolkits (Python, TimescaleDB/PostGIS, Pandas/Pygmo2, and Matplotlib/Seaborn); this application demonstrated good results using cellular network signaling data and GPS trajectories collected in Huilongguan district, Beijing, China. Moreover, this demonstration illustrates that probe mobile monitoring is emerging as a critical technology for traffic monitoring supplements, which can help develop a comprehensive view of the roads and reduce the cost of monitoring a large area.

Research on the Application of WPT-EEMD Method in the Fault Diagnosis of AESPS

Bao Yan,Shi Weifeng,Chen Peichen,Ding Qiuyi,Zhu Chen 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.8

The Band Offset at CdS/Cu2ZnSnS4 Heterojunction Interface

Ji Li,Qingyang Du,Weifeng Liu,Guoshun Jiang,Xuefei Feng,Wenhua Zhang,Junfa Zhu,Changfei Zhu 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.4

The band offset at the CdS/Cu2ZnSnS4 heterojunction interface is studied by measuring the valence band spectra using synchrotron radiation photoemission spectroscopy. The Cu2ZnSnS4 thin films are prepared by the sulfurization of electrodeposited Cu-Zn-Sn precursors. A CdS overlayer is sequentially grown on the Cu2ZnSnS4 thin films from a chemical bath deposition process. Valence band spectra were obtained before and after each period of growth to study the electronic structure at the heterojunction interface. The valence band offset was determined to be 0.96 eV, and the conduction band offset was determined to be .0.06 eV. This means that the CdS/Cu2ZnSnS4 hetrojunction has a ‘type II’ band alignment which will cause largescale recombination at the interfaces and will not be suitable for solar cells fabrication.