DISCOVERY AND MASS MEASUREMENTS OF A COLD, 10 EARTH MASS PLANET AND ITS HOST STAR

Muraki, Y.,Han, C.,Bennett, D. P.,Suzuki, D.,Monard, L. A. G.,Street, R.,Jorgensen, U. G.,Kundurthy, P.,Skowron, J.,Becker, A. C.,Albrow, M. D.,Fouqué,, P.,Heyrovský,, D.,Barry, R. K.,Beau IOP Publishing 2011 The Astrophysical journal Vol.741 No.1

<P>We present the discovery and mass measurement of the cold, low-mass planet MOA-2009-BLG-266Lb, performed with the gravitational microlensing method. This planet has a mass of m(p) = 10.4 +/- 1.7 M-circle plus and orbits a star of mass M-star = 0.56 +/- 0.09 M-circle dot at a semimajor axis of a = 3.2(-0.5)(+1.9) AU and an orbital period of P = 7.6(-1.5)(+7.7) yrs. The planet and host star mass measurements are enabled by the measurement of the microlensing parallax effect, which is seen primarily in the light curve distortion due to the orbital motion of the Earth. But the analysis also demonstrates the capability to measure the microlensing parallax with the Deep Impact (or EPOXI) spacecraft in a heliocentric orbit. The planet mass and orbital distance are similar to predictions for the critical core mass needed to accrete a substantial gaseous envelope, and thus may indicate that this planet is a 'failed' gas giant. This and future microlensing detections will test planet formation theory predictions regarding the prevalence and masses of such planets.</P>

Application of a Coupled Harmonic Oscillator Model to Solar Activity and El Niño Phenomena

Yasushi Muraki 한국우주과학회 2018 Journal of Astronomy and Space Sciences Vol.35 No.2

Solar activity has an important impact not only on the intensity of cosmic rays but also on the environment of Earth. In the present paper, a coupled oscillator model is proposed to explain solar activity. This model can be used to naturally reduce the 89-year Gleissberg cycle. Furthermore, as an application of the coupled oscillator model, we herein attempt to apply the proposed model to El Niño-southern oscillation (ENSO). As a result, the 22-year oscillation of the Pacific Ocean is naturally explained. Finally, we search for a possible explanation for coupled oscillators in actual solar activity.

How different is shoulder motion in subjects with symptomatic rotator cuff tear from asymptomatic controls?

Takayuki Muraki,Hiroaki Ishikawa,Shuhei Morise,Nobuyuki Yamamoto,Hirotaka Sano,Eiji Itoi,Shin-ichi Izumi 대한견주관절의학회 2014 대한견주관절학회 학술대회논문집 Vol.2014 No.3

Autocorrelation Coefficient for Detecting the Frequency of Bio-Telemetry

Yoshiya Muraki,Yukako Yagi,Kiyoshi Kurokawa,Isao Nakajima 한국멀티미디어학회 2022 The journal of multimedia information system Vol.9 No.3

A MATLAB program was developed to calculate the half-wavelength of a sine-curve baseband signal with white noise by using an autocorrelation function, a SG filter, and zero-crossing detection. The frequency of the input signal can be estimated from 1) the first zero-crossing (corresponding to ¼λ) and 2) the R value (the Y axis of the correlogram) at the center of the segment. Thereby, the frequency information of the preceding segment can be obtained. If the segment size were optimized, and a portion with a large zero-crossing dynamic range were obtained, the frequency discrimination ability would improve. Furthermore, if the values of the correlogram for each frequency prepared on the CPU side were prepared in a table, the volume of calculations can be reduced by 98%. As background, period detection by autocorrelation coefficients requires an integer multiple of 1/2λ (when using a sine wave as the object of the autocorrelation function), otherwise the correlogram drawn by R value will not exhibit orthogonality. Therefore, it has not been used in bio-telemetry where the frequencies move around.

Communication-Centered Project Management for Requirements Definition Phase

Ishii, Nobuaki,Muraki, Masaaki Korean Institute of Industrial Engineers 2012 Industrial Engineeering & Management Systems Vol.11 No.1

Requirements definition, which determines a project baseline, has a strong impact on the success of a project. However, since in-depth requirements are gradually revealed through the requirements definition process, the requirements definition is not a straight forward process and often falls into disorder. Thus project management standpoints are critical for the success of the requirements definition. In this paper, we present a framework and mechanisms of communication-centered project management, which controls the requirements definition process based on the situation of communication-oriented activities among stakeholders. In addition, we present a communication-centered project plan with a planning method. The project plan, which represents a time schedule of requirements definition activities, is made by a simulation-optimization algorithm using a stakeholder matrix showing the relations of requirements domains and relevant stakeholders. The effectiveness and the significance of communication-centered project management at the requirements definition phase are demonstrated by numerical examples.

Exploring the appropriate test methods to examine the efects of frefghter personal protective equipment on mobility

손수영,Satoshi Muraki,Yutaka Tochihara 한국의류학회 2022 Fashion and Textiles Vol.9 No.1

This study aimed to ascertain the appropriate test methods for the investigation of the efect of personal protective equipment on mobility of frefghters. Nine male volunteers performed a physical performance test (crawl, obstacle course, side-to-side jumps, heavy-object drag, and step-ups), functional balance test (functional reach, timed up and go, and wooden plank time), range of motion test, and subjective evaluation under four clothing conditions with diferent weights and combinations of personal protective equipment. The results showed that physical performance, functional balance ability, and joint angles signifcantly declined with increased weight of personal protective equipment. On subjective evaluation, wearing heavy personal protective equipment increased perceived exertion and discomfort on movement. Our results proved that some of our test methods, including the obstacle course, side-toside jumps, functional reach, timed up and go, range of motion test, and subjective evaluation, can be used to examine the mobility of personal protective equipment wearers. The fndings of this study provide an efective guide for researchers and frefghters regarding the evaluation of mobility with personal protective equipment, as well as for manufacturers in the development of enhanced, comfortable personal protective equipment.

보조적인 힘이 근장력 변동성의 크기와 불규칙성에 미치는 영향

최지원,Satoshi Muraki,Ping Yeap Loh 대한인간공학회 2024 大韓人間工學會誌 Vol.43 No.4

Objective: This study aims to observe how force output patterns alter when assistive force is provided during mechanically assisted force coordination with isometric elbow flexion. Background: Force coordination between humans and assistive robots requires human muscle force to be released in response to mechanical assistance. However, little is known about how motor performance of muscle force release with assistive force is different from the one without assistance. This study investigated how force variability parameters of coefficient of variation (CV) of force output, sample entropy, and stabilization time alter during isometric force control with assistive force. Method: Eleven male participants (mean: 24.4; SD: 1.5) participated in this experiment. Electromyography electrodes were placed on the surfaces of biceps and triceps muscles. The participant maintained an isometric elbow flexion force of 47N with the dominant arm along a linear trajectory shown on a screen. Under the conditions of assistive force provision, the assistive force was gradually provided as 25% or 50% of the isometric force for 0.5s by operating the actuator so that the participant could release their muscle force. Under the conditions where assistive force was not provided, the participant released their isometric force by 25% or 50% along with the visual guidance on the screen. From the manual force output, release stabilization time of force control was calculated and the CV and sample entropy were computed to represent size of force variability and time-series data irregularity, respectively. Results: Regardless of whether assistance was provided, the activation of biceps and triceps brachii muscles decreased after force release. This study found that compared to the visually guided conditions, mechanically assisted conditions showed a lower CV, longer stabilization time, and higher sample entropy. When the muscle force was greatly released (50% release of the isometric force), a longer stabilization time and greater CV were observed, but the entropy was lower compared to the slight muscle force release (25% release). Conclusion: This study suggests that when the magnitude of force release is relatively large, the size of force variability increases, while the irregularity decreases. This could imply that humans probably have potential adaptability for greater assistive force provided during mechanically assisted force coordination. Application: The results of the current study can be used to determine the amount of assistive force provided during human-robot collaboration.

Dual Frobenius manifolds of minimal gravity on disk

Bawane, Aditya,Muraki, Hisayoshi,Rim, Chaiho Springer-Verlag 2018 Journal of high energy physics Vol.2018 No.3

Open KdV hierarchy and minimal gravity on disk

Bawane, Aditya,Muraki, Hisayoshi,Rim, Chaiho Elsevier 2018 Physics letters: B Vol.783 No.-

<P><B>Abstract</B></P> <P>We show that the minimal gravity of Lee–Yang series on disk is a solution to the open KdV hierarchy proposed for the intersection theory on the moduli space of Riemann surfaces with boundary.</P>

The Effects of Touch Button Size to the Operability of Touchscreen

( Jinghong Xiong ),( Satoshi Muraki ),( Kiyotaka Fukumoto ) 한국감성과학회 2014 춘계학술대회 Vol.2014 No.-

The present study investigated the influence of button size on the operability of a touch panel screen and compared this influence between young adults and the elderly. Twenty-one young adults (age: 22.3±1.5 years) and twenty elderly people (age: 68.1±4.9 years) operated the interface of a touch panel screen with their right index finger. It displayed 0-9 numeric square buttons at 6 different size conditions (6, 8, 10, 12, 14 and 16 mm). Smaller buttons at and below 10 mm increased the operation time and error rate, and decreased the subjective overall operability. The influence of button size was greater in the elderly than in the young adults. The reaction positions were located to the right of the center of the button, which made the reaction position approach the right outline of the button, especially for smaller buttons. These results suggest that smaller buttons should be avoided in interfaces on touch panel screens, especially those used by the elderly.