Tokyo National College of Technology

Tokyo, Japan

Tokyo National College of Technology

Tokyo, Japan

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Mayuzumi R.,University of Electro - Communications | Kojima T.,Tokyo National College of Technology
2012 International Symposium on Information Theory and Its Applications, ISITA 2012 | Year: 2012

Information hiding scheme using direct sequence spread spectrum (DS-SS) technique is one of the effective ways to embed secret information into media contents securely. In recent years, information hiding schemes based on complete complementary codes have been proposed. In particular, it has been shown that it is possible to embed a large message into an image by a blind steganography scheme based on complete complementary codes. However, it has been pointed out that bit errors occur since the source image is not referred to by the blind scheme. In this paper, we apply low-density parity-check (LDPC) codes to the steganography scheme and analyze the bit error rate (BER) performance by numerical experiments. © 2012 IEICE Institute of Electronics Informati.


Matsui Y.,Tokyo National College of Technology | Kimura T.,Tokyo National College of Technology | Nakano K.,University of Electro - Communications
Proceedings of the IEEE International Conference on Control Applications | Year: 2010

In this paper, a simple scheme to estimate frequency responses of linear time-invariant single-input single-output (SISO) systems based on closed-loop step response data is investigated. The method uses only a single set of step response data of plants under closed-loop operating conditions. The input and output of a plant are filtered by a simple bandpass filter, and the frequency response of the plant is obtained with the Discrete Fourier Transforms (DFTs) of the filtered input and output signals. The validity of the proposed method is illustrated through simulations and experiments. © 2010 IEEE.


Hatano A.,Tokyo National College of Technology | Shoji R.,Tokyo National College of Technology
Comparative Biochemistry and Physiology - C Toxicology and Pharmacology | Year: 2010

A new model for predicting time course toxicity of heavy metals was developed by extending the effective ratio of biotic ligand binding with toxic heavy metals to the total biotic ligand for 50% of test organisms (f50) derived by the Biotic Ligand Model (BLM). BLM has been well-known as a useful model for prediction of heavy metal toxicity. BLM can consider the effect of exposure conditions such as pH and Ca2+ on heavy metal toxicity. In addition to the exposure conditions, heavy metal toxicity is strongly dependent on exposure time. In this study, BLM is extended to predict time dependency of heavy metal toxicity by connecting with the concept of primary reaction. The model developed in this study also generates the estimation of the 50% effect concentration (EC50) for toxicologically unknown organisms and heavy metals. Two toxicological and kinetic constants, f50,0 and k, were derived from the initial value of f50 (f50,0) and a time constant (k) independent of time. The model developed in this study enables us to acquire information on the toxicity of heavy metals such as Cu, Cd and Co easily. © 2009 Elsevier Inc. All rights reserved.


Mayazumi R.,Tokyo National College of Technology | Kojima T.,Tokyo National College of Technology
Proceedings - 7th International Conference on Intelligent Information Hiding and Multimedia Signal Processing, IIHMSP 2011 | Year: 2011

Digital watermarking schemes based on complete complementary codes have been proposed. It has been pointed out that the watermarking schemes can be extended to the steganography scheme because complete complementary code has good correlation properties. In this paper, we propose a blind steganography algorithm which does not need to refer any cover data in the extraction process. In addition, we theoretically evaluate the maximum size of the embedded data and numerically analyze the limit to embed the secret messages under the condition where the peak signal to noise ratio(PSNR) is over 35[dB]. Bit error rate and bit error distribution of the proposed method are also included in this paper. © 2011 IEEE.


Kojima T.,Tokyo National College of Technology | Ohtani N.,NHK Media Technology Inc.
2012 International Symposium on Information Theory and Its Applications, ISITA 2012 | Year: 2012

Complete complementary code is a family of the spread spectrum sequences with good correlation properties. In this study, the properties of the private and the blind digital fingerprinting schemes using complete complementary codes were evaluated. It is revealed that the proposed scheme is sufficiently robust against collusion attacks by employing a large embedding coefficient in the private case. In addition, in the blind case where the source image cannot be referred to, it was shown that the robustness against collusion attacks could be improved by applying a method called QIM (quantization index modulation) and employing a set of appropriate parameters. © 2012 IEICE Institute of Electronics Informati.


Ohtsuka T.,Tokyo National College of Technology
Proceedings - International Conference on Pattern Recognition | Year: 2012

This paper presents new fingerprint minutiae detection by the advanced ridge flux analysis. The considerable processing time taken by the conventional approaches, most of which use the ridge thinning process with a rather large calculation time, is a problem that has recently attracted increased attention. Though Ridge flux analysis method without using thinning process is proposed in order to reduce the computational time, there still remains a problem with low detection accuracy. The proposed approach is applied to detect minutiae by analyzing the curvature of ridge contours to achieve both of the computation time reduction and higher detection accuracy. The experimental results show that the proposed approach can achieve a reduction in calculation time, while achieving the same success detection rate as that of the conventional approaches. © 2012 ICPR Org Committee.


Maedan S.,Tokyo National College of Technology
Progress of Theoretical Physics | Year: 2010

It is known that, in the chiral limit, spatially inhomogeneous chiral condensate occurs in the Nambu-Jona-Lasinio (NJL) model at finite density within a mean-field approximation. We study here how the introduction of current quark mass affects the ground state with the spatially inhomogeneous chiral condensate. Numerical calculations show that, even if the current quark mass is introduced, the spatially inhomogeneous chiral condensate can take place. To obtain the ground state, the thermodynamic potential is calculated with a mean-field approximation. The influence of finite current mass on the thermodynamic potential consists of the following two parts. One is a part coming from the field energy of the condensate, which favors the inhomogeneous chiral condensate. The other is a part coming from the Dirac sea and Fermi sea, which favors the homogeneous chiral condensate. We also find that when the spatially inhomogeneous chiral condensate occurs, the baryon number density becomes spatially inhomogeneous.


Saito S.,Tokyo National College of Technology
Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B | Year: 2010

This study focuses on water hammer pumps that can effectively use the water hammer phenomenon and allow fluid transients without drive sources, such as electric motors. An understanding of water hammer pumps' operating conditions and an evaluation of their basic hydrodynamic characteristics are significant for determining whether they can be widely used as an energy-saving device in the future. However, these conventional studies have not described the pump performance in terms of pump head and flow rate, common measures indicating the performance of pumps, and are not useful in fully evaluating the pump characteristics. As a first stage for the understanding of water hammer pump performance in comparison to the characteristics of typical turbo pumps, this study focuses on understanding the basic hydrodynamic characteristics of water hammer pumps and experimentally examines how the hydrodynamic characteristics are affected by the inner diameter of the drive and lifting pipes, the form and capacity of the air chamber, and the angle of the drive pipe, which are believed to be representative geometric form factors.


Tanaka A.,Tokyo National College of Technology
International Conference on Ubiquitous and Future Networks, ICUFN | Year: 2013

We have developed locally exploitable multihop communication systems that consist of easily-obtainable devices and enable user-oriented communications. By narrowing their purposes, difficult challenges for multihops are resolved. Taking advantage of pervasiveness, we study multihops to be locally embedded in WANs, and newly develop heterogeneously multihop-linked-cooperative-robots by integrating our multihop technologies: (a) smartphone multimedia-chatting, (b) infrared-communications with error-correction, switching, multipath-prevention and route-diversity, (c) energy-conserving-routing with mobility-prediction and procedure-integration in UHF systems. Uni-/multi-/broadcast, barrier-free and language-independent interface, visible-light-communication and heterogeneity are incorporated. Consequently, the cooperative-robots hold promise as search-and-rescue robots in disaster sites such as earthquakes as well as in daily life. © 2013 IEEE.


Ohtsuka T.,Tokyo National College of Technology
Proceedings of the 12th IAPR Conference on Machine Vision Applications, MVA 2011 | Year: 2011

This paper presents a new fingerprint minutiae extraction approach that is based on the analysis of the ridge flux distribution. The considerable processing time taken by the conventional approaches, most of which use the ridge thinning process with a rather large calculation time, is a problem that has recently attracted increased attention. We observe that the features of a ridge curve are very similar to those of a vector flux such as a line of electric force or a line of magnetic force. In the proposed approach, vector flux analysis is applied to detect minutiae without using the ridge thinning process in order to reduce the computation time. The experimental results show that the proposed approach can achieve a reduction in calculation time, while achieving the same success detection rate as that of the conventional approaches.

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