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Competitiveness in Car Distribution Industry between Korea and China
Jun Yu 한국유통과학회 2015 KODISA ICBE (International Conference on Business Vol.2015 No.-
This research understand both 2 country’s trade structure to strengthen Korea-China economic cooperations and examine trade drawback to analyze causes which affect trade and by its improvement direction, find out way of trade expansion. As Northeast asian countries are geographically adjacent to Northwest coast of Pacific ocean, in case economic cooperations are intensified, transportation & communication costs could be diminished as well as transaction cost caused by economic exchanges could be minimized. In order to analyze trade decision factor of both 2 countries, Index of trade intensity invented by trade intensity theory(Kruger, A.O.1997) is used to analyze it. Even though specific factor should be materialized in terms of analysis of trade decision factor, realistically, concreted explanations are difficult as there are so many unsolved factors and its diversifications. Therefore, this research focus on reviewing trade structural factors and external trade structural factor of trade decision factor’s analysis, namely, time-series analysis is efficient.First, these Index of A value/ B value means Korean against Chinese market share/Korean against world market share, of which is comparative market intensity. Second, So, Korea is taking comparative advantage of export specialization and on the contrary, China is taking comparative advantage of import specialization respectively. Third, RCA indexes are considerably improved compared to that of 2000. However, still as RCA indexes are much smaller than +1 means Korea is in a position to comparative disadvantage against China compared to those of other industries. This research is analyzed by quantitative measurement with trade intensity theory, trade specialization and revealed comparative advantage index to see how inter-trade relations are changed between Korea and China during past 10 years(2000, 2005, 2012). Through this survey of time series, we can figure out structural factor of trade dependence relations
Conversion of syngas to C2+ oxygenates over Rh-based/SiO2 catalyst: The promoting effect of Fe
Jun Yu,Dongsen Mao,Lupeng Han,Qiangsheng Guo,Guanzhong Lu 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.3
The effect of Fe promoter on the catalytic properties of Rh–Mn–Li/SiO2 catalyst for CO hydrogenation was investigated. The catalysts were comprehensively characterized by means of X-ray diffraction (XRD), N2adsorption–desorption, temperature programmed reduction (TPR), temperature programmed desorption (TPD), temperature programmed surface reaction (TPSR), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Activity testing results showed that low loading of Fe (≤0.1 wt%)improved the reactivity and yield of C2+ oxygenates; however, the opposite effect appeared at the high values of Fe (>0.1 wt%). Characterization results suggested that the addition of Fe strengthened the Rh–Mn interaction and increased the desorption/transformation rate of adsorbed CO, which could be responsible for the increase of CO conversion. But on the other hand, the existence of Fe might deposit over the Rh surface, and decreased the number of active sites, resulting in the decrease of CO conversion when the Fe amount was excessive. The selectivity to C2+ oxygenates varied inversely with the reducibility of Rh oxide species. Moreover, it is proposed that the transformation of dicarbonyl Rh+(CO)2into H–Rh–CO is favorable for the formation of C2+ oxygenates, and the hydrogenation ability of Fe can increase the hydrogenation of acetaldehyde to ethanol.
Stable and robust $\ell_p$-constrained compressive sensing recovery via robust width property
Jun Yu,Zhiyong Zhou 대한수학회 2019 대한수학회지 Vol.56 No.3
We study the recovery results of $\ell_p$-constrained compressive sensing (CS) with $p\geq 1$ via robust width property and determine conditions on the number of measurements for standard Gaussian matrices under which the property holds with high probability. Our paper extends the existing results in Cahill and Mixon \cite{cm} from $\ell_2$-constrained CS to $\ell_p$-constrained case with $p\geq 1$ and complements the recovery analysis for robust CS with $\ell_p$ loss function.
Jun Yu,Bo Ding,Yongjun He 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.11
To analyze data from multi-level view, reduce computational burden, and improve fault diagnosis accuracy, a novel fault diagnosis method of rolling bearings based on mean multigranulation decision-theoretic rough set (MMG-DTRS) and non-naive Bayesian classifier (NNBC) is proposed in this paper. First, fault diagnosis features of rolling bearings in training samples are extracted to construct MMG-DTRS. Then, the significance degree of condition attribute in MMG-DTRS is defined to quantitatively measure the influence of condition attributes with respect to the decision ability of an information system. An attribute reduction algorithm based on MMG-DTRS is applied to acquire a lower dimensional condition attribute set, which reduces computational complexity and avoids the interference of irrelevant or redundant condition attributes. Finally, NNBC is constructed to classify rolling bearing conditions in test samples. The classification procedures by using NNBC are given. The performance of the proposed method is validated and the advantages are investigated by using a fault diagnosis experiment of rolling bearings. Experimental investigations demonstrate the proposed method is effective and reliable in identifying fault categories and fault severities of rolling bearings.
Jun Yu,Zhenyu Guo 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.1
Planet bearing vibration signals are complex and non-stationary owing to the time-varying vibration transmission path from fault point to accelerometers. In addition, due to the influence of speed and load variation, planetary gearboxes often operate under varying conditions, which causes the acquired vibration signals to be nonlinear. These seriously degrade the performance of the RUL prediction methods. Moreover, there are only few training samples for the RUL prediction of planet bearings. To address these problems, an RUL prediction method of planet bearings using conditional deep recurrent generative adversarial network (C-DRGAN) and action discovery (AD) is presented. First, gated recurrent unit neural network is integrated with conditional generative adversarial network to construct the C-DRGAN, which extracts fault features from nonlinear and non-stationary signals so as to realize the RUL prediction of planet bearings under small samples and varying conditions. Then, the training algorithm based on AD is employed to train the C-DRGAN to enhance convergence speed and reduce training time. Finally, a multiple linear regression classifier is utilized to predict the RUL of planet bearings. The performance of the presented method is validated through an accelerated fatigue life experiment of planet bearings. Experimental analyses demonstrate that this method possesses strong processing adaptability to nonlinear and non-stationary signals and obtains excellent performance under small samples.
Jun Yu,Decai Li,Nannan Di,Ningning Guo 한국자기학회 2019 Journal of Magnetics Vol.24 No.2
The self-suspension of magnet in magnetic fluid has been widely used in micromechanical systems, sensors, and dampers. The magnetic field associated with the ring magnet is obtained by numerical calculation and simulation through which the axial magnetic levitation force is calculated, and the numerical calculation, simulation, and experimental results agree with each other. The influence of the radial eccentricity of the ring magnet on the axial magnetic levitation force is studied, the ring magnet will experience a maximum axial magnetic levitation force without radial eccentricity. With the increase of radial eccentricity and the decrease of the distance between the bottom of the ring magnet and container, the axial magnetic levitation force will continue to decrease. But it is worth noting that the magnitude of the change caused by radial eccentricity is negligible compared to that of the axial magnetic levitation force.