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Search Results: 1 - 10 of 206 matches for " Tadahiro Ohmi "
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A Codebook Design Method for Robust VQ-Based Face Recognition Algorithm  [PDF]
Qiu Chen, Koji Kotani, Feifei Lee, Tadahiro Ohmi
Journal of Software Engineering and Applications (JSEA) , 2010, DOI: 10.4236/jsea.2010.32015
Abstract: In this paper, we present a theoretical codebook design method for VQ-based fast face recognition algorithm to im-prove recognition accuracy. Based on the systematic analysis and classification of code patterns, firstly we theoretically create a systematically organized codebook. Combined with another codebook created by Kohonen’s Self-Organizing Maps (SOM) method, an optimized codebook consisted of 2×2 codevectors for facial images is generated. Experimental results show face recognition using such a codebook is more efficient than the codebook consisted of 4×4 codevector used in conventional algorithm. The highest average recognition rate of 98.6% is obtained for 40 persons’ 400 images of publicly available face database of AT&T Laboratories Cambridge containing variations in lighting, posing, and expressions. A table look-up (TLU) method is also proposed for the speed up of the recognition processing. By applying this method in the quantization step, the total recognition processing time achieves only 28 msec, enabling real-time face recognition.
Fast Search for MPEG Video Clips from Large Video Database Using Combined Histogram Features
Feifei Lee,Koji Kotani,Qiu Chen,Tadahiro Ohmi
Lecture Notes in Engineering and Computer Science , 2010,
A Local Search Method Using Histogram Features for Fast Retrieval of DNA Sequences
Qiu Chen,Koji Kotani,Feifei Lee,Tadahiro Ohmi
Lecture Notes in Engineering and Computer Science , 2010,
International Journal of Bioinformatics Research , 2011,
Abstract: DNA sequence search is a fundamental topic in bioinformatics. The Smith-Waterman algorithmachieved highest accuracy among various sequence alignment tools, but it usually spends much computationaltime to search on large DNA sequence database. On the contrary, BLAST and FASTA have improved the searchspeed by using heuristic approaches, by there is a possibility of missing an alignment or giving inaccurate output.This paper presents an efficient hierarchical method to improve the search speed while the accurate is being keptconstant. For a given query sequence, firstly, a fast histogram based method is used to scan the sequences in thedatabase. A large number of DNA sequences with low similarity will be excluded for latter searching. The Smith-Waterman algorithm is then applied to each remainder sequences. Experimental results show the proposedmethod combining histogram information and Smith-Waterman algorithm is a more efficient algorithm for DNAsequence search
Qiu Chen, Koji Kotani, Feifei Lee and Tadahiro Ohmi
International Journal of Bioinformatics Research , 2012,
Abstract: DNA sequence search is a very important topic in bioinformatics algorithm development. However, this task usually spends much computational time to search on large DNA sequence database. In this paper, we propose an efficient hierarchical DNA sequence search algorithm to improve the search speed while the accuracy is being kept constant. For a given query DNA sequence, firstly, a fast local search algorithm using histogram features is used as a filtering mechanism before scanning the sequences in the database. An overlapping processing is newly added to improve the robustness of the algorithm. A large number of DNA sequences with low similarity will be excluded for latter searching. The Smith-Waterman algorithm is then applied to each remainder sequences. Experimental results using GenBank sequence data show the proposed algorithm combining histogram information and Smith-Waterman algorithm is more efficient for DNA sequence search.
Electron cloud effects: codes and simulations at KEK
K. Ohmi
Physics , 2013, DOI: 10.5170/CERN-2013-002.219
Abstract: Electron cloud effects had been studied at KEK-Photon Factory since 1995. e-p instability had been studied in proton rings since 1965 in BINP, ISR and PSR. Study of electron cloud effects with the present style, which was based on numerical simulations, started at 1995 in positron storage rings. The instability observed in KEKPF gave a strong impact to B factories, KEKB and PEPII, which were final stage of their design in those days. History of cure for electron cloud instability overlapped the progress of luminosity performance in KEKB. The studies on electron cloud codes and simulations in KEK are presented.
Beam-beam effects under the influence of external noise
K. Ohmi
Physics , 2014, DOI: 10.5170/CERN-2014-004.69
Abstract: Fast external noise, which gives fluctuation into the beam orbit, is discussed in connection with beam-beam effects. Phase noise from crab cavities and detection devices (position monitor) and kicker noise from the bunch by bunch feedback system are the sources. Beam-beam collisions with fast orbit fluctuations with turn by turn or multi-turn correlations, cause emittance growth and luminosity degradation. We discuss the tolerance of the noise amplitude for LHC and HL-LHC.
Effects of Improving Public Services for Tourism Developments in Islands: The Case of Remote Islands in Nagasaki, Japan  [PDF]
Tadahiro Okuyama, Hayato Ishihara
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.36018
Abstract: Growths of numbers of tourists who stay long-term in tourism sites are an important policy for local governments in islands due to their locations that are far from urban areas. However, many tourists hesitate to stay long-term in islands owing to not only the expensive travel costs but also the lack of public services in islands. The purpose of this study is to examine effects of improving public services in islands for tourists’ willingness to pays (WTPs) and non-tourists’ attitudes for long-term stays. Data on tourism activity for islands, Nagasaki, Japan were used. Respondents were asked about their WTPs for long-term stays and their needs for public services of islands; reductions of costs for rent or purchasing houses for long-term stays and travel costs, easy to take a vacation, to enhance medical services, educational services and job search services. The logit model was used for estimations. Median and mean values of WTPs (per year) were calculated JPY 151,629 (USD 1184) and JPY 242,110 (USD 3008). Positive effects on five public services (without travel costs) were confirmed. For example, the median values of WTPs were increased to JPY 478,369 (USD 5943) when the medical services were improved, and JPY 1,484,704 (USD 18,446) when all public services were improved. The results showed that improvement of public services have the effect 1) to improve tourists’ benefits and 2) to change many non-tourists’ attitudes from the rejection of staying long term in islands to the acceptance. Thus, results indicate that it would be better for central and/or local governments in islands to enhance islands’ public services.
Dynamic imaging of a small artery underneath skin surface of a human finger by optical coherence tomography  [PDF]
Masato Ohmi, Mitsuo Kuwabara, Masamitsu Haruna
Journal of Biomedical Science and Engineering (JBiSE) , 2013, DOI: 10.4236/jbise.2013.63030

OCT is a powerful tool for detection of physiological functions of micro organs underneath the human skin surface, besides the clinical application to ophthalmology, as recently demonstrated by the authors’ group. In particular, dynamics of peripheral vessels can be observed clearly in the time-sequential OCT images. Among the vascular system, only the small artery has two physiological functions both for the elastic artery and for muscle-controlled one. It, therefore, is important for dynamic analysis of blood flow and circulation. In the time-sequential OCT images obtained with 25 frames/sec, it is found that the small artery makes a sharp response to sound stress for contraction and expansion while it continues pulsation in synchronization with the heartbeats. This result indicates that the small artery exhibits clearly the two physiological functions for blood flow and circulation. In response to sound stress, blood flow is controlled effectively by thickness change of the tunica media which consists of five to six layers of smooth muscles. It is thus found that the thickness of the tunica media changes remarkably in response to external stress, which shows the activity of the sympathetic nerve. The dynamic analysis of the small artery presented here will allow us not only to understand the mechanism of blood flow control and also to detect abnormal physiological functions in the whole vascular system.

Dynamic Analysis of Mental Sweating by the Time-Sequential Piled-Up En-Face OCT Images  [PDF]
Masato Ohmi, Yuki Wada, Motomu Tanigawa
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.37A004

In this paper, the dynamic analysis of mental sweating for sound stimulus of a few tens of eccrine sweat glands is performed by the time-sequential piled-up en-face optical coherence tomography (OCT) images with the frame spacing of 3.3 sec. In the experiment, the amount of excess sweat can be evaluated simultaneously for a few tens of sweat glands by piling up of all the en-face OCT images. Strong non-uniformity is observed in mental sweating where the amount of sweat in response to sound stimulus is different for each sweat gland. Furthermore, the amount of sweat is significantly increased in proportion to the strength of the stimulus.

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