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Hyo Kee Kim,Ahram Han,Sang Hyun Ahn,고현민,Chris Tae Young Chung,Kwang Woo Choi,Sang-Il Min,Jongwon Ha,Seung-Kee Min 대한혈관외과학회 2021 Vascular Specialist International Vol.37 No.1
Purpose: Native arteriovenous fistula (AVF) is the first choice for hemodialysis access; however, the maturation failure rate remains high. Hence, balloon-assisted maturation (BAM) is increasingly being used to overcome maturation failure. This study evaluated the outcomes of BAM and compared the differences between radial-cephalic (RC) and brachial-cephalic (BC) AVF. Materials and Methods: Between January 2013 and December 2017, 1,622 new AVFs were created. BAM was considered if the AVF did not satisfy the criteria for hemodynamic maturation (6-mm diameter and 500-mL/min flow rate within 8 weeks after the operation). Results: Of the 1,622 AVFs, BAM was performed in 142 patients (8.75%). There were 92 RC and 50 BC AVFs. Multivariate analyses revealed that ipsilateral central vein catheter history was the sole risk factor for maturation failure after BAM. Oneyear functional primary patency (FPP) and functional secondary patency (FSP) in RC AVFs were higher than those in BC AVFs without statistical significance (FPP, RC vs. BC: 70.9% vs. 50.9%, P=0.099; FSP, 95.5% vs. 81.1%, P=0.146). Further, based on the multivariate analysis, the independent risk factors for FPP in the RC and BC AVFs were the number of BAMs (odds ratio [OR], 3.05; 95% confidence interval [CI], 1.11-8.37; P=0.03) and age (OR, 1.04; 95% CI, 1.00-1.07; P=0.04), respectively. Conclusion: BAM is a relatively good salvage method with tolerable patency. However, the risk factors for patency and the outcomes of BAM differ between RC and BC AVFs.
Environmental-Adaptive RSSI-Based Indoor Localization
Hyo-Sung Ahn,Wonpil Yu IEEE 2009 IEEE transactions on automation science and engine Vol.6 No.4
<P>This paper addresses a novel method for localizing a stationary object in an indoor office environment. The proposed method utilizes the received-signal-strength index (RSSI) of radio signals radiating from fixed reference nodes and reference tags placed at known positions to generate a precise signal propagation model. Signal attenuation parameters are updated online according to environmental variation; thus, the proposed method has environmental-adaptation capabilities. Subsequent experiments were conducted to demonstrate the superiority of the proposed technique over a commercial location-based service (LBS) chipset.</P>
Geometrical Attitude Determination Algorithm Based on Vector Measurements
AHN, Hyo-Sung,LEE, Seon-Ho THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIEN 2010 Transactions of the Japan Society for Aeronautical Vol.53 No.179
<P>This paper addresses a novel vector-based attitude determination algorithm on the basis of geometrical configuration of external reference vectors. The proposed method called a geometrical attitude determination algorithm can be used for the attitude estimation of moving vehicles when two external reference vectors are partially measured on three orthogonal body axes. Applications of the new method range from the ground robotics navigation to satellite attitude control. Numerical simulations demonstrate that the algorithm can be reliably utilized for the three-axis attitude determination in the presence of inaccurately-measured reference vectors.</P>
Exact Maximum Singular Value Calculation of an Interval Matrix
Ahn, Hyo-Sung,Chen, YangQuan IEEE 2007 IEEE transactions on automatic control Vol.52 No.3
<P>In this note, we present a method for calculating the maximum singular value of an interval matrix. First, we provide an algorithm for calculating the maximum singular value of a square interval matrix. Then, based on this algorithm, we extend the result to non-square interval matrix case and to the case of computing the minimum singular value. Through numerical examples, the validity of the suggested methods is illustrated. Particularly, we compare the newly-proposed method with an existing method to show that the new method finds the correct bound of the maximum singular value with no exception</P>
Isolation of 151 Mutants that Have Developmental Defects from T-DNA Tagging
Ahn, Ji Hoon,Kim, Joonki,Yoo, Seong Jeon,Yoo, So Yeon,Roh, Hyungmin,Choi, Jun-Hyuk,Choi, Mi Suk,Chung, Kyung Sook,Han, Eun Ju,Hong, Sung Myun,Jung, Sung Hye,Kang, Hyo Jin,Kim, Bo Kyung,Kim, Mi Duk,Kim Oxford University Press 2007 Plant & cell physiology Vol.48 No.1
<P>In order to understand the mechanisms underlying plant development, a necessary first step involves the elucidation of the functions of the genes, via the analysis of mutants that exhibit developmental defects. In this study, an activation tagging mutant library harboring 80,650 independent <I>Arabidopsis</I> transformants was generated in order to screen for developmental mutants. A total of 129 mutants manifesting dominant developmental abnormalities were isolated, and their T-DNA insertion loci were mapped. The activation of one or more genes adjacent to a T-DNA insertion locus was confirmed in eight dominant mutants. A gene adjacent to the right border was usually activated by the 35S enhancers. Interestingly, the transcriptional activation of multiple genes within a broad range was observed in one of the mutants, which raises the possibility that activation by the 35S enhancers was not limited strictly to a single gene. In order to gain a better understanding of sexual reproduction in higher plants, we isolated 22 mutants exhibiting defects in female gametophyte development, and determined their T-DNA insertion loci. We propose that this mutant population may prove useful in the further determination of the functions of genes that play important roles in plant development.</P>
A prototype of digital photogrammetric algorithm for estimating roughness of rock surface
Hyo-Sung Lee,Ki-Won Ahn 한국지질과학협의회 2004 Geosciences Journal Vol.8 No.3
This study introduces the efficiency of using prototype digital photogrammetry for measuring the roughness of rock surfaces, employing digital stereo images obtained from a high resolution Kodak DCS 420 non-metric digital camera and a Rolleiflex 6006 metric film camera. To measure the surface roughness of test objects in the case of non-topographic applications, reference surfaces are mathematically estimated using the least squares method. The roughness processing capability of a digital camera and a metric film camera is evaluated using an arbitrarily chosen reference surface on the sample being studied. Then the results are compared with the measurements obtained using a laser profilometer. The RMS roughness and Z2s parameters estimated using the DCS 420 non-metric digital camera ranges from 0.001 mm to 0.067 mm and from 0.007 to 0.073, when compared to the laser profilometer values. In the case of the Rolleiflex 6006 metric film camera, the RMS and the Z2s parameters range from 0.010 mm to 0.056 mm and from 0.005 to 0.031. The prototype photogrammetric algorithm is consequently suitable for measuring rock surface roughness.
Iterative learning control with dirac-delta function under state alignment condition
Sang-Chul Lee,Young-Hun Lim,Hyo-Sung Ahn 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10
In this paper, we develop iterative learning control (ILC) algorithms when the final states of previous iteration are equal to the initial states of current iteration, which is called state alignment. When a new iteration begins along continuous time domain without stopping for a reset, the typical ILC algorithm is modified using dirac-delta function such that the state alignment condition is satisfied.