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Home > Archives > Vol.6, No.2

Vol.6, No.2






Very-Low-Cost Powered Air-Purifying Respirator (PAPR) gDistancing-Free Mask Industry (DFM-I) Prototype No.1h and Proposal for a Lockdown-Free Industry

Edwin Carcasona, Ronald M. Galindo, Akihiro Takita, Ethelda Magalang, Tabetha S. Galindo, Seiji Hashimoto, Takao Yamaguchi, Edgar U. Tibay, Dongwei Shu, Haruo Kobayashi, Kenji Amagai, Naoya Ohta, Noriaki Yoshiura, Anna Kuwana, Ayako Yano, and Yusaku Fujii

Journal of Technology and Social Science, Vol.6, No.2, pp.1-4, 2022.

Abstract: A very-low-cost Powered Air-Purifying Respirator (PAPR) gDistancing-Free Mask Industry (DFM-I) Prototype No.1h, which is suitable for use by the factory workers, is developed. This development is done in Cebu, Philippines under an international research collaboration project between Philippines, Singapore, and Japan researchers, in which the vaccine-independent and lockdown-free society/nation by means of spread of low-cost PAPR, is proposed and pursued. The present status and future prospect of DFM-I project in the whole DFM project are discussed.

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Vibration and Acoustic Analysis for the Speaker Cover of the Automotive Trim

Yoshio Kurosawa, Yuji Leandro Fujihara, Manabu Sasajima, and Mitsuharu Watanabe

Journal of Technology and Social Science, Vol.6, No.2, pp.5-10, 2022.

Abstract: In general, a mesh cover is attached to the front of the speaker to protect the speaker. Experiments have confirmed that the sound pressure changes depending on the distance between the speaker and the cover, the thickness of the cover, and the like. The result of calculating this phenomenon using the FE model is introduced. It was confirmed that due to the influence of the cover, the sound pressure increased due to the resonance phenomenon below a specific frequency, and the sound pressure decreased due to the sound insulation effect above that frequency range. Similar results were obtained when the cover thickness was changed. We also report the calculation results even though the hole diameter is changed and when the distance between the cover and air is changed.

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Sound and Vibration Analysis of the Acoustic Fields Involving Felt when the Panel is Inputed

Yoshio Kurosawa, Manabu Sasajima, and Mitsuharu Watanabe

Journal of Technology and Social Science, Vol.6, No.2, pp.11-19, 2022.

Abstract: In automobiles, noise may be generated in the passenger compartment, which is a closed space with a panel that is the outer wall and a breathable trim. We created a simple model based on these assumptions and performed experiments and vibration acoustic analysis. We placed a partition plate with a hole in an acrylic pipe that has an inner diameter of 100 mm and vibrated the iron plate (panel) placed on the bottom with hammer. Then we measured the vibration and sound pressure level when the hole shape of the partition plate was changed and felt was placed. In addition, we create a similar FE model and report the results of the analysis of the sound pressure level when the acoustic characteristics of felt placed in the holes of the partition are changed.

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FE model for loosely-supported setup of impedance tube measurement

Yoshio Kurosawa

Journal of Technology and Social Science, Vol.6, No.2, pp.20-26, 2022.

Abstract: In impedance tube measurement, the sound absorption coefficient measurement result may change due to contact between the sample and the tube wall. Loosely-supported setup has been developed in which the sample does not contact the tube wall. However, there is a gap between sample and tube wall. Also, diameter of sample is larger than inner diameter of tube. Therefore, the effect of the gap between the sample and the tube wall and the sample diameter was calculated using a finite element model. In this paper, I report the calculation results of fiber material (glass wool) using Johnson Champoux Allard (JCA) model and urethane foam using Biot-Allard model.

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Charge Domain Folding ADC for Multi-bit AD Modulator

Xiongyan Li, Tianrui Feng, Lengkhang Nengvang, Haijun Lin, Shogo Katayama, Jianglin Wei, Anna Kuwana, Kazufumi Naganuma, Kiyoshi Sasai, Junichi Saito, Katsuaki Morishita, and Haruo Kobayashi

Journal of Technology and Social Science, Vol.6, No.2, pp.27-37, 2022.

Abstract: This paper describes consideration on folding ADC usage inside a multi-bit AD modulator. The folding ADC requires only one comparator for each bit with analog preprocessing circuits; hence, it requires only small hardware and its power consumption is small for 5-bit or 6-bit resolution. Further its latency is small (one or two clock cycles) compared to an SAR ADC or a pipelined ADC. We propose to use a 5-bit or 6-bit ADC and a 3-bit DAC inside the modulator. We consider that thanks to these characteristics, 5-bit or 6-bit AD modulator can be implemented using the folding ADC. Also, our designed charge mode folding ADC employing discrete-time signal processing in Gray code output format is shown with SPICE simulation results using TSMC 0.18m CMOS SPICE parameters. It may suffer from nonlinearity due to device mismatches, but it will be noise-shaped inside the modulator and its effects will be alleviated.

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Research on Sound Volume Improvement of Assembled Whistle

Yoshio Kurosawa and Makoto Ono

Journal of Technology and Social Science, Vol.6, No.2, pp.38-45, 2022.

Abstract: We have developed a prefabricated whistle that is convenient to carry in order to call for help in the event of a disaster. Create by assembling business card-sized flat materials (Kent paper and coated paper used for ordinary business cards). This content has already been patented, but the volume (sound pressure level) was not sufficient. We will report the results of improving the sound pressure level and peak frequency by devising the internal structure and blowing method so that the rescuer can easily hear it. And, we will create a finite element model and introduce the results that qualitatively agree with the experimental results regarding the peak frequency.

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Effect of Wall Sound Absorption by Car Door Speakers and Sound Pressure Distribution in the Car

Yoshio Kurosawa, Manabu Sasajima, Mitsuharu Watanabe, and Yoshiteru Uchida

Journal of Technology and Social Science, Vol.6, No.2, pp.46-54, 2022.

Abstract: In order to analyze how the sound emitted from the speaker of an automobile changes due to the influence of the wall, we performed an experiment and a calculation using the FE model for the case of a rectangular parallelepiped box with and without a sound absorbing material on the wall. The calculation results were able to roughly reproduce the experimental results. Next, we created a simple FE model that simulates the interior space of a car, and used the actual vehicle to determine the effects of sound absorption on the ceiling, floor, and seats, and changes in sound pressure level and sound pressure distribution when sound absorbing materials were added. We report the measurement and analysis results by the FE model.

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Development of Hands-on Teaching Materials for Cryptography in Senior High School

Kenji Yamaguchi, Anna Kuwana, and Katsuhisa Kagami

Journal of Technology and Social Science, Vol.6, No.2, pp.55-61, 2022.

Abstract: Cryptography is an essential technology used to secure current Internet communications. It is implemented against the background of the theory of difficulty in mathematics (e.g., the difficulty of prime factorizing large composite numbers). Additionally, cryptography is an ideal teaching material for learning mathematics and information technology. Since textbooks do not fully cover the theoretical aspects of cryptography, it is crucial to develop this technology. Therefore, this project aims to broaden the student base and develop teaching materials that interest children and students of various ages in mathematics and information technology. We developed graphical learning materials that can be used in class or at home for students to learn about cryptography. We believe that it will be beneficial for students and teachers to create more user-friendly and easy-to-learn learning materials based on the results of the previous yearfs materials.

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