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Speed and Current Sensor Fault Detection and Isolation Based on Adaptive Observers for IM Drives
Yu, Yong,Wang, Ziyuan,Xu, Dianguo,Zhou, Tao,Xu, Rong The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5
This paper focuses on speed and current sensor fault detection and isolation (FDI) for induction motor (IM) drives. A new, accurate and high-efficiency FDI approach is proposed so that a system can continue operating with good performance even in the presence of speed sensor faults, current sensor faults or both. The proposed three paralleled adaptive observers are capable of current sensor fault detection and localization. By using observers, the rotor flux and rotor speed can be estimated which allows the system to run under the speed sensorless vector control mode when a speed sensor fault occurs. In order to detect speed sensor faults, a threshold-based scheme is proposed. To verify the feasibility and effectiveness of the proposed FDI strategy, experiments are carried out under different conditions based on a dSPACE DS1104 induction motor drive platform.
[r, s, t; f]-COLORING OF GRAPHS
Yu, Yong,Liu, Guizhen Korean Mathematical Society 2011 대한수학회지 Vol.48 No.1
Let f be a function which assigns a positive integer f(v) to each vertex v $\in$ V (G), let r, s and t be non-negative integers. An f-coloring of G is an edge-coloring of G such that each vertex v $\in$ V (G) has at most f(v) incident edges colored with the same color. The minimum number of colors needed to f-color G is called the f-chromatic index of G and denoted by ${\chi}'_f$(G). An [r, s, t; f]-coloring of a graph G is a mapping c from V(G) $\bigcup$ E(G) to the color set C = {0, 1, $\ldots$; k - 1} such that |c($v_i$) - c($v_j$ )| $\geq$ r for every two adjacent vertices $v_i$ and $v_j$, |c($e_i$ - c($e_j$)| $\geq$ s and ${\alpha}(v_i)$ $\leq$ f($v_i$) for all $v_i$ $\in$ V (G), ${\alpha}$ $\in$ C where ${\alpha}(v_i)$ denotes the number of ${\alpha}$-edges incident with the vertex $v_i$ and $e_i$, $e_j$ are edges which are incident with $v_i$ but colored with different colors, |c($e_i$)-c($v_j$)| $\geq$ t for all pairs of incident vertices and edges. The minimum k such that G has an [r, s, t; f]-coloring with k colors is defined as the [r, s, t; f]-chromatic number and denoted by ${\chi}_{r,s,t;f}$ (G). In this paper, we present some general bounds for [r, s, t; f]-coloring firstly. After that, we obtain some important properties under the restriction min{r, s, t} = 0 or min{r, s, t} = 1. Finally, we present some problems for further research.
Strategy of formant enhancement in digital hearing aid
Yuyong Jeon,Dong-hyeouck Bang,Dong-gwon Yang,Sangmin Lee 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
Digital hearing aid users often complain of difficulty in understanding speech in the presence of background noise. Various speech enhancement and SNR improvement algorithms have been applied in digital hearing aids for improving speech perception in the noisy environment. Although those speech enhancements are good for someone, these can be not good for someone else. It can be because masking patterns of each people are different, and masking between formants of speech can be occurred by the formant which enhanced excessively. By enhanced formants for improving speech perception, other formants can be masked. In a word, to perform the excessive speech enhancement by digital hearing aids would be not able to improve speech perception. By this reason, for each person, to know about quantity of formant enhancement that masking is started, to check the masking pattern is required to hearing aid users. In this study, to define the limit of quantity of formant enhancement fitting to each person, we tested with the formant enhanced speech, and tried to find a level difference that masking is started between first formant and second formant using the hearing impaired and normal hearing people. The test is composed of 5 steps; puretone test, speech reception threshold (SRT), word recognition test (WRT), puretone masking test and speech masking test. We confirmed the masking effect by enhanced formants in the speech.
Improved Method for Determining the Height of Center of Gravity of Agricultural Tractors
( Yuyong Kim ),( Jaeseung Noh ),( Seungyeop Shin ),( Byoungin Kim ),( Sunjung Hong ) 한국농업기계학회 2016 바이오시스템공학 Vol.41 No.4
This study aimed to improve the method for determining the position of the center of gravity for agricultural tractors. Methods: The proposed method uses trigonometric functions and coordinate transformation. Data were measured according to the ISO 789-6 test procedures for the center of gravity of agricultural tractors. The height calculated using the proposed method was compared with that determined from an AutoCAD drawing. To find the center of gravity of the tractor, the algorithm for finding the intersection of the two lines was used. Results: The vertical height from the ground to the center of gravity is 682.06 mm. The vertical coordinates obtained from the calculation and the drawing were the same. Conclusions: The developed method uses trigonometric and polar coordinate transformation. The method was compared and verified with the AutoCAD drawing results. The results indicate that users can apply this developed method instead of the plotting method which is an inconvenient and time-consuming. Further, users can program Microsoft Excel to easily determine the vertical coordinate. In addition, researchers will propose this method to the ISO as a standard method for determining the center of gravity in accordance with ISO 789-6.
( Yuyong Kim ),( Byounggap Kim ),( Seungyeoub Shin ),( Byoungin Kim ),( Sunjung Hong ) 한국농업기계학회 2015 바이오시스템공학 Vol.40 No.3
Training power tiller operators in safe farming is necessary to avoid farming accidents. With the continuing progress in computational technology, driving simulators have become increasingly popular for conducting such training. Purpose: The objective of this study is to develop mock control devices and data acquisition apparatus for a tiller simulator. Methods: Except for the stand and tail wheel adjusting levers, the mock control devices were developed using a tiller handle assay. The data acquisition apparatus was realized using an embedded data-logging device and LabVIEW, the system design software. Results: The control devices of a real handle assay were successfully mimicked by the mock operator control devices, which used sensors for the relevant measurements. The data from the mock devices were acquired and transmitted to the main computer at intervals of 10 ms via Wi-Fi. Conclusions: The developed mock control devices operate similar to real power tillers and can be utilized in power tiller training simulators.
Wall Displacement and Ground-Surface Settlement Caused by Pit-in-Pit Foundation Pit in Soft Clays
Yuyong Sun,Hongju Xiao 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.4
The number of pit-in-pit foundation pit is increasing quickly because of the continuous utilization of underground spaces in urban areas. Based on the co-construction project of Shanghai Museum of Natural History foundation pit and Shanghai Metro Line 13 foundation pit in Shanghai, China, the deformation characteristics of pit-in-pit foundation pit are researched by field observation and centrifugal model tests. The lateral wall displacement of inner foundation pit includes global deformation caused by the outer foundation pit excavation and deflection caused by the excavation of itself. The effect of inner foundation pit excavation on the lateral wall displacement of outer foundation pit and ground-surface settlement is smaller. The two factors affecting the deformation characteristics of pit-in-pit foundation pit, the distance between inner and outer foundation pits (D) and the excavation width of inner foundation pit (Win), are analyzed by centrifugal model tests. The result shows that the maximum lateral wall displacements of inner and outer foundation pits decrease nearly linearly with the increase of D, but increase with the increase of Win.