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Journal of Technology and Social Science (JTSS, J. Tech. Soc. Sci.)

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ISSN 2432-5686



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Home > Archives > Vol.3, No.1

Vol.3, No.1






Sleep-monitoring system for detecting infant behavior

Yuuki Tanaka, Nobuaki Nakazawa, Yoichi Shiraishi, Kazuhiro Motegi and Hisaki Watari

Journal of Technology and Social Science, Vol.3, No.1, pp.1-6, 2019.

Abstract: This paper shows results of an experiment performed for studying infantsf sleep via a novel monitoring system, comprising 16 pressure sensors beneath a mattress. We analyzed the changes in the pressure acting on the distributed pressure sensors to estimate sleeping conditions. Here, we found characteristics of the sensor data for the following three conditions: breathing, turning over on the mattress, and leaving the mattress. During the infant-sleep observation, a periodical signal appears in the pressure sensor data when the infant was breathing. Center of gravity data derived from the 16 pressure sensors drastically changed when the infant turned over on the mattress. Furthermore, the sum of the pressure data on the 16 pressure sensors decreased when the infant left the mattress. This analysis is useful for determining a threshold for detecting abnormal infant-sleep conditions.

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Redundant SAR ADC Algorithm for Minute Current Measurement

Hirotaka Arai, Takuya Arafune, Shohei Shibuya, Yutaro Kobayashi, Koji Asami and Haruo Kobayashi

Journal of Technology and Social Science, Vol.3, No.1, pp.7-13, 2019.

Abstract: This paper investigates a successive approximation register (SAR) AD conversion algorithm for measuring a minute current source. We consider the case that the input current is very small, and the sample & hold (SH) circuit in front of the SAR ADC takes relatively long time to settle completely. If a binary search SAR ADC is used, it has to wait until the signals in the SH circuit settle completely because the binary search has no redundancy. Then we propose to use a redundant search SAR ADC which can start to operate before its complete settling. Even if a decision error of successive comparisons occurs in the previous stage because of the incomplete setting of the SH circuit, it can be corrected in the subsequent stages, thanks to the redundancy. Then the SAR AD conversion time can be shortened. We will present its operation principle and simulation results.

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Development of Material and Form for Vibration Isolation Gloves

Yoshio Kurosawa, Kazuyuki Nagashima, Tatsuyuki Edano and Takeshi Ochiai

Journal of Technology and Social Science, Vol.3, No.1, pp.14-21, 2019.

Abstract: Anti-vibration gloves are used as protective equipment for vibration obstacles, but due to the thick anti-vibration materials of gloves, poor workability is pointed out by operators such as difficulty in manual work using fingertips. Therefore, in view of workability, we aimed to develop protective equipment that maintains vibration isolation performance even if the thickness of the vibration proof material is thin from the present. Vibration measurement of ten kinds of materials with different materials and shapes was carried out, and vibration damping characteristics were analyzed and compared. With regard to the urethane-based material that was effective, we were able to develop a material with vibration damping performance (vibration transmission ratio less than 1) with a sheet thickness of 5 mm by examining the sheet shape, designing by simulation and vibration measurement / analysis.

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Study on Energy Recovery Ventilator with Water Spray Cooling System

Ayako Yano, Takuya Nakasaka, Kenji Amagai, Masahisa Uenishi and Takashi Matsuzaki

Journal of Technology and Social Science, Vol.3, No.1, pp.22-27, 2019.

Abstract: Energy recovery ventilators with water spray cooling systems were tested in experiments. To reduce the air temperature, water spray cooling systems were installed with conventional energy recovery ventilators. Two installation positions of the water spray cooling system were tested, on the outdoor and indoor sides. The temperature and humidity of the exchanged air were measured under various conditions of the outdoor temperature. Then, temperature exchange efficiency was estimated from the measured temperature reduction. The results confirmed that the water spray cooling system increased temperature exchange efficiency.

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Pulse Coding Controlled Switching Converter with Automatic Notch Frequency Tracking for Radio Receiver

Yifei Sun, Yi Xiong, Nobukazu Tsukiji, Yasunori Kobori and Haruo Kobayashi

Journal of Technology and Social Science, Vol.3, No.1, pp.28-36, 2019.

Abstract: This paper proposes an EMI spread spectrum technique with automatically setting the notch frequency using the pulse coding controlled method of the DC-DC switching converter for the communication equipment. This proposed EMI spread spectrum technique does not distribute the switching noise into some specified frequency bands; we can automatically prevent the noises from spreading into important frequencies (such as AM, FM bands). The notch in the spectrum of the switching pulses will be generated using two types of pulse coding method (PWC and PWPC). Notch frequency Fn is automatically set to that of the received signal by adjusting the clock frequency Fck using the equation Fn = (N + 0.5) Fck. Here N is a positive integer. We have confirmed with simulations that the proposed technique is effective for EMI reduction and notch generation.

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Propagation of Stress Waves in Viscoelastic Rods and Plates (2) -Acoustic Impedance of a Viscoelastic Rod: Validation with Literature Data-

Ryuzo Horiguchi and Takao Yamaguchi

Journal of Technology and Social Science, Vol.3, No.1, pp.37-55, 2019.

Abstract: We derived the explicit analytical expression of the complex wave number of a longitudinal wave in a viscoelastic rod and a flexural wave in a viscoelastic beam. This paper proposes a method for obtaining the acoustic impedance from a complex wave number for stress waves in viscoelastic rods. This acoustic impedance is a frequency response function (FRF) in the form of a ratio of acoustic pressure to particle velocity. The complex wave number is related to the viscoelasticity through the formula presented in our previous paper. Calculation results were validated via a comparison with literature data. We first converted the acoustic impedance into an FRF in the form of the ratio of the displacement at the edge to the excitation force. Subsequently, this FRF was compared with the results of cork from the study by Policarpo et al. Our results were consistent with their results.

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Chondroepitrochlearis - an Extremely Rare Variant of Pectoralis Major Muscle - a Case Report

Sani Baimai, Phattarapong Predapramote and Sitha Piyaselakul

Journal of Technology and Social Science, Vol.3, No.1, pp.56-62, 2019.

Abstract: Chondroepitrochlearis muscle, a truly rare muscle of pectoralis major muscle, was discovered in the right upper extremity of a 78-year-old Thai female. This demonstrates the first report of the anomaly in Thai. Chondroepitrochlearis was a muscular slip that originated from the inferior border of the right pectoralis major muscle, external abdominal oblique muscle, costal cartilages, or costochondral junctions. This muscle was superficial to biceps brachii muscle. It became a musculotendinous slip at the middle of the arm and then ran down to insert at the medial epicondyle of the humerus. Moreover, some tendinous parts also merged with the medial intermuscular septum. In addition, ulnar nerve and medial cutaneous nerve of the arm were observed at posterior to this tendinous slip. In a clinical aspect, there was no sign of ulnar nerve entrapment at this region. Nerve and arterial supplies of chondroepitrochlearis muscle were medial pectoral nerve and lateral thoracic artery, respectively.

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