Longitudinal Assessment of Intravoxel Incoherent Motion Diffusion Weighted Imaging in Evaluating the Radio-sensitivity of Nasopharyngeal Carcinoma Treated with Intensity-Modulated Radiation Therapy

Youping Xiao,Ying Chen,Yunbin Chen,Zhuangzhen He,Yiqi Yao,Jianji Pan 대한암학회 2019 Cancer Research and Treatment Vol.51 No.1

Purpose Intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) was evaluated regarding its ability to preliminarily predict the short-term treatment response of nasopharyngeal carcinoma (NPC) following intensity-modulated radiation therapy. Materials and Methods IVIM-DWI with 14 b-factors (0-1,000 sec/mm2) was performed with a 3T MR system on 47 consecutive NPCs before, during (end of the 5th, 10th, 15th, 20th, and 25th fractions), and after fractional radiotherapy. IVIM parametrics (D, f, and D*) were calculated and compared to the baseline and xth fraction. Patients were categorized into responders and non-responders after radiotherapy. IVIM parametrics were also compared between subgroups. Results After fractional radiations, the D (except D5 and D at the end of the 5th fraction) after radiations were larger than the baseline D0 (p < 0.05), and the post-radiation D* (except D*5 and D*10) were smaller than D*0 (p < 0.05). f0 was smaller than f5 and f10 (p < 0.001) but larger than fend (p < 0.05). Furthermore, greater D5, D10, D15, and f10 coupled with smaller f0, D*20, and D*25were observed in responders than non-responders (all p < 0.01). Responders also presented larger D10, f10, D*20, and D*20 than non-responders (p < 0.05). Receiver operating characteristic curve analysis indicated that the D5, D*20, and f10 could better differentiate responders from non-responders. Conclusion IVIM-DWI could efficiently assess tumor treatment response to fractional radiotherapy and predict the radio-sensitivity for NPCs.

Analysis on Temperature Distribution and Current-Carrying Capacity of GIL Filled with Fluoronitriles-CO₂ Gas Mixture

Chen, Geng,Tu, Youping,Wang, Cong,Cheng, Yi,Jiang, Han,Zhou, Hongyang,Jin, Hua The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

Fluoronitriles-$CO_2$ gas mixtures are promising alternatives to $SF_6$ in environmentally-friendly gas-insulated transmission lines (GILs). Insulating gas heat transfer characteristics are of major significance for the current-carrying capacity design and operational state monitoring of GILs. In this paper, a three-dimensional calculation model was established for a GIL using the thermal-fluid coupled finite element method. The calculated results showed close agreement with experimentally measured data. The temperature distribution of a GIL filled with the Fluoronitriles-$CO_2$ mixture was obtained and compared with those of GILs filled with $CO_2$ and $SF_6$. Furthermore, the effects of the mixture ratio of the component gases and the gas pressure on the temperature rise and current-carrying capacity of the GIL were analyzed. Results indicated that the heat transfer performance of the Fluoronitriles-$CO_2$ gas mixture was better than that of $CO_2$ but worse than that of $SF_6$. When compared with $SF_6$, use of the Fluoronitriles-$CO_2$ gas mixture caused a reduction in the GIL's current-carrying capacity. In addition, increasing the Fluoronitriles gas component ratio or increasing the pressure of the insulating gas mixture could improve the heat dissipation and current-carrying capacity of the GIL. These research results can be used to design environmentally-friendly GILs containing Fluoronitriles-$CO_2$ gas mixtures.

Analysis on Temperature Distribution and Current-Carrying Capacity of GIL Filled with Fluoronitriles-CO₂ Gas Mixture

Geng Chen,Youping Tu,Cong Wang,Yi Cheng,Han Jiang,Hongyang Zhou,Hua Jin 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

Fluoronitriles-CO₂ gas mixtures are promising alternatives to SF6 in environmentallyfriendly gas-insulated transmission lines (GILs). Insulating gas heat transfer characteristics are of major significance for the current-carrying capacity design and operational state monitoring of GILs. In this paper, a three-dimensional calculation model was established for a GIL using the thermal-fluid coupled finite element method. The calculated results showed close agreement with experimentally measured data. The temperature distribution of a GIL filled with the Fluoronitriles-CO₂ mixture was obtained and compared with those of GILs filled with CO₂ and SF6. Furthermore, the effects of the mixture ratio of the component gases and the gas pressure on the temperature rise and current-carrying capacity of the GIL were analyzed. Results indicated that the heat transfer performance of the Fluoronitriles-CO₂ gas mixture was better than that of CO₂ but worse than that of SF₆. When compared with SF6, use of the Fluoronitriles-CO₂ gas mixture caused a reduction in the GIL’s current-carrying capacity. In addition, increasing the Fluoronitriles gas component ratio or increasing the pressure of the insulating gas mixture could improve the heat dissipation and current-carrying capacity of the GIL. These research results can be used to design environmentally-friendly GILs containing Fluoronitriles-CO₂ gas mixtures.

Experimental investigation of the preferred Strouhal number used in self-resonating pulsed waterjet

Deng Li,Youping Chen,Yong Kang,Zu’an Wang,Xiaoliang Wang,Qi Fan,Miao Yuan 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.9

Self-resonating pulsed waterjet (SRPW) is superior to plain waterjet in many ways and is being employed in numerous applications. To further improve the performance of SRPW, the optimal value of the preferred Strouhal number (S d ), which is used to determine the chamber length of a self-resonating nozzle, was experimentally studied at inlet pressures of 10 MPa and 20 MPa. The axial pressure oscillation peak and amplitude were used to evaluate the performance of SRPW, in order to find the optimum S d value. Results show that S dvalue determines the self-resonance behavior of an organ-pipe nozzle and greatly affects the intensity of the axial pressure oscillation. Under the experimental conditions, the optimum S d values are 0.315 and 0.278 respectively, corresponding to inlet pressures of 10 MPa and 20 MPa. Compared with the default value of 0.3 obtained from air jet experiment, the optimum S d value at inlet pressure of 10 MPa is a little larger and oppositely a bit smaller at inlet pressure of 20 MPa. Thus, if the inlet pressure is not considered, S d value of 0.3 is reasonable for determining the chamber length of a self-resonating nozzle for generating effective SRPW.

Temporal distribution, influencing factors and pollution sources of urban ambient air quality in Nanchong, China

Hong Zhou,Youping Li,Huifang Liu,Zhongyu Fan,Jie Xia,Shanli Chen,Yuxiang Zheng,Xiaocui Chen 대한환경공학회 2015 Environmental Engineering Research Vol.20 No.3

The PM10, SO₂ and NO₂ mass concentrations were obtained over five years from monitoring stations across Nanchong, a southwest city in China. Changes in urban air quality over time, as well as the factors influencing that change, were evaluated based on air pollutant concentrations, the Air Pollution Index (API), and the Comprehensive Pollution Index (P). The results showed that the total annual mean PM10, SO₂ and NO₂ concentrations over the five years studied were 61.1±1.1, 45.0±3.9 and 34.9±4.9 μg·m-3, respectively. The annual mean concentrations displayed a generally decreasing trend; lower than the annual mean second-level air quality limit. Meanwhile, the annual mean API values were in a small range of 52-53, the air quality levels were gradeⅡ, and P values were 1.06-1.21 less than the slight level (P ≤ 1.31). Total monthly mean PM10, SO₂, NO₂ concentrations, and API and P values were consistently higher in winter and spring than during autumn and summer. The results of a correlation analysis showed that temperature and pressure were the major meteorological factors influencing pollution levels. Pollution sources included industrial coal and straw burning, automobiles exhaust and road dust, fireworks, and dust storms.

Research on Liquefaction Characteristics of SF6 Substitute Gases

Zhikang Yuan,Youping Tu,Cong Wang,Sichen Qin,Geng Chen 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

SF₆ has been widely used in high voltage power equipment, such as gas insulated switchgear (GIS) and gas insulated transmission line (GIL), because of its excellent insulation and arc extinguishing performance. However, SF₆ faces two environmental problems: greenhouse effect and high liquefaction temperature. Therefore, to find the SF₆ substitute gases has become a research hotspot in recent years. In this paper, the liquefaction characteristics of SF₆ substitute gases were studied. Peng–Robinson equation of state with the van der Waals mixing rule (PR-vdW model) was used to calculate the dew point temperature of the binary gas mixtures, with SF₆, C₃F₈, c-C₄F₈, CF₃I or C₄F₇N as the insulating gas and N₂ or CO₂ as the buffer gas. The sequence of the dew point temperatures of the binary gas mixtures under the same pressure and composition ratio was obtained. SF₆/N₂ < SF₆/CO₂ < C₃F₈/N₂ < C₃F₈/CO₂ < CF₃I/N₂ < CF₃I/CO₂ < c-C₄F₈/N₂ < C₄F₇N/N₂ < c-C₄F₈/CO₂ <C₄F₇N/CO₂. SF₆/N₂ gas mixture showed the best temperature adaptability and C₄F₇N/CO₂ gas mixture showed the worst temperature adaptability. Furthermore, the dew point temperatures of the SF₆ substitute gases at different pressures and the upper limits of the insulating gas mole fraction at -30℃, -20℃ and -10℃ were obtained. The results would supply sufficient data support for GIS/GIL operators and researchers.

Influence of Forging Temperature on the Microstructures and Mechanical Properties of a Multi-Directionally Forged Al–Cu–Li Alloy

Hailin He,Kanghua Chen,Youping Yi,Wen You,Yonglin Guo,Bingxiang Wang,Jiaguo Tang,Research Institute of Light Alloy, Central South University,Shiquan Huang 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.2

Optimization of forging process to improve the microstructure and mechanical properties of 2195 Al–Cu–Li alloy forgingsis an urgent issue. In this study, a homogenized 2195 alloy ingot was subjected to multi-directional forging (MDF), annealing,and forging at 500 °C, 420 °C, and 240 °C with a 50% reduction in cross-sectional area, followed by a T8 heat treatment(involving solution, quenching, cold compression, and aging). The microstructural evolution during the process and thefinal mechanical properties in three orthogonal directions were examined. The results showed that the grain structures ofthe alloy were significantly refined after MDF by dynamic recrystallization (DRX), but the structure was thermally unstableand formed coarse grains during subsequent annealing by static recrystallization (SRX). The T8-treated samples forged at500 °C, 420 °C, and 240 °C obtained fine and uniform grain structures by DRX, inhomogeneous grain structures by partialSRX, and uniform, equiaxed grain structures by full SRX, respectively. The average grain size of the forging increased withdecreasing forging temperature because more significant SRX occurred for the forging that was deformed at lower temperatures. The grain structures had minimal influence on precipitation behavior and strength but had a significant influence onelongation. The fine and uniform grain structures improved the elongation; whereas, the inhomogeneous grain structures,which contained extremely large grains, significantly deteriorated the elongation. The uniform, equiaxed grain structuresdecreased the anisotropy in three orthogonal directions and maintained fine elongation even though the average grain sizeof the forging was the largest.

Research on Liquefaction Characteristics of SF6 Substitute Gases

Yuan, Zhikang,Tu, Youping,Wang, Cong,Qin, Sichen,Chen, Geng The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

$SF_6$ has been widely used in high voltage power equipment, such as gas insulated switchgear (GIS) and gas insulated transmission line (GIL), because of its excellent insulation and arc extinguishing performance. However, $SF_6$ faces two environmental problems: greenhouse effect and high liquefaction temperature. Therefore, to find the $SF_6$ substitute gases has become a research hotspot in recent years. In this paper, the liquefaction characteristics of $SF_6$ substitute gases were studied. Peng-Robinson equation of state with the van der Waals mixing rule (PR-vdW model) was used to calculate the dew point temperature of the binary gas mixtures, with $SF_6$, $C_3F_8$, $c-C_4F_8$, $CF_3I$ or $C_4F_7N$ as the insulating gas and $N_2$ or $CO_2$ as the buffer gas. The sequence of the dew point temperatures of the binary gas mixtures under the same pressure and composition ratio was obtained. $SF_6/N_2$ < $SF_6/CO_2$ < $C_3F_8/N_2$ < $C_3F_8/CO_2$ < $CF_3I/N_2$ < $CF_3I/CO_2$ < $c-C_4F_8/N_2$ < $C_4F_7N/N_2$ < $c-C_4F_8/CO_2$ < $C_4F_7N/CO_2$. $SF_6/N_2$ gas mixture showed the best temperature adaptability and $C_4F_7N/CO_2$ gas mixture showed the worst temperature adaptability. Furthermore, the dew point temperatures of the $SF_6$ substitute gases at different pressures and the upper limits of the insulating gas mole fraction at $-30^{\circ}C$, $-20^{\circ}C$ and $-10^{\circ}C$ were obtained. The results would supply sufficient data support for GIS/GIL operators and researchers.

한류가 한국 화장품 브랜드의 이미지에 미치는 영향

한충민(Choong Min Han),진희(Xi Chen),이상엽(Sang Youp Rhee) 한국경영학회 2011 經營學硏究 Vol.40 No.4

This study is intended to empirically examine how the Korean wave in China affects Chinese consumers` images of Korean cosmetics brands. Specifically it is proposed that the Korean wave positively influences images of Korean cosmetics brands through favorable Korean images and favorable attitudes toward advertisements featuring Korean drama stars. Many Korean marketers, in order to captialize on goodwill built through popular Korea TV dramas and stars, have employed TV advertising featuring Korean TV stars. In other words, the Korean Wave in China may lead to Chinese favorable perceptions of Korean brands through Korean wave advertising. On the other hand, one can argue that the Korean wave can lead to Chinese favorable images toward Korean brands without Korean wave advertising. the Korean wave can lead to favorable images of Korea, which may influence Chinese perceptions of Korean brands throuhg country-of-origin effects. Therefore, we examine two possible paths on how the Korean wave may affect Chinese images of Korean cosmetic brands through Korean wave advertising and country-of-origin effects. The Korean wave was examined with Chinese affections toward Korean television dramas and drama stars. A structural model was proposed to test these propositions. Surveys were conducted with 181 young female Chinese in Peking. The respondents were mostly graduate students from two major universities in Peking. They were selected because firstly they were active users of cosmetics and secondly they were also believed to be reasonably familiar with Korean dramas and TV stars. We chose Korean stars and cosmetic brands which are quite well known to the respondents. They were Song Hye Kyo and Bae Yong Jun with Laneige and The Face Shop brands. We tested internal consistencies of the measures through Cronbach alpha coefficients and congeneric reliabilities, convergent and nomological validities through confirmatory factor analysis. We found that our measures were reasonably reliable and valid. In addition, Amos 6.0 was employed to estimate structural path coefficients. The overall goodness of fit indices for the model were reasonable good, which suggest a reasonable good fit for the proposed model. The findings suggest that Chinese women with strong affection toward Korean television dramas and stars tend to have favorable images of Korea and favorable attitudes toward advertisements featuring Korean stars. and finally positive perceptions of Korean cosmetics brands. In addition, we found that Korean drama stars showed greater influence in images of the brands that do Korean dramas. Interestingly we also found that the mediating role of Korean country image in brand attitudes were greater than that of attitudes toward advertisements features Korean drama stars. Finally, marketing implications were discussed. Our findings suggest that Korean marketers without employing Korean wave advertising featuring Korean stars may still benefit greatly from goodwill built from the Korean wave. In addition, since stars` influences are greater than TV dramas, marketers perhaps ought to concentrate more on Korean stars than the content of TV dramas in their marketing.