Faculty Profiles - KOMATSU Mitsuru

Papers - KOMATSU Mitsuru

Division display 61 - 80 of about 129 ／ All the affair displays >>

小型半導体チップ型センサによる地盤の間隙変化の計測方法に関する基礎的実験 Reviewed

小松満, 竹下祐二, 二川雅登, 不破泰, 鈴木彦文, 熊倉信行, 吉野晃

地盤と建設 33 ( 1 ) 163 - 168 2015.12

静電容量センサによるベントナイト系材料の水分量計測に関する基礎的研究（共著） Reviewed

小松満, 佃明恵, 榊利博

地盤と建設 33 ( 1 ) 37 - 44 2015.12

河川堤防の法面における遠隔水分量モニタリングに向けた実証研究（共著） Reviewed

小松満, 竹下祐二, 二川雅登, 不破泰, 鈴木彦文, 熊倉信行, 吉野晃

地盤と建設 33 ( 1 ) 169 - 174 2015.12

Development of in situ permeability test using constant discharge method for sandy soils Reviewed

A. Rifa’i, Y. Takeshita, M. Komatsu

World Academy of Science, Engineering and Technology, International Journal of Environmental, Chemical, Ecological, Geological and Geophysical Engineering 9 ( 11 ) 1264 - 1268 2015.11

Fabrication of a Hydrophilic Property Impedance Sensor to Stably Monitor Soil Water Content for Slope Failure Prognostics Reviewed

Masato Futagawa, Tatsumi Ito, Hikofumi Suzuki, Yasushi Fuwa, Arumi Kunii, Yuji Takeshita, Mitsuru Komatsu, Minoru Watanabe

2015 IEEE SENSORS 1445 - 1448 2015

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

To minimize the damage caused by slope failure, knowledge of the increase in water content in mountain soil is important. Our group has been studying miniaturized impedance sensor for multipoint measurements in the soil. To improve contact characteristics between sensor surface and free water in soil, SiOx film of hydrophilic property covered on our conventional sensor chip. For contact property test, the sensor chip measured impedance of model soils. The proposed sensor achieved to stable contact the free water in the soil. Moreover, the chip operated for long period of time in mountain slope. The sensor could measure nearly theoretical outputs which responded to rainfalls. We succeeded to fabricate the stably soil monitor sensor with hydrophilic film SiOx.

Web of Science

researchmap

Realization of a Safe and Secure Society using ICT in Shiojiri-City, Nagano Prefecture, Japan -Towards the Creation of a Smart Citie- Reviewed

Hikofumi Suzuki, Yasushi Fuwa, Masato Futagawa, David K. Asano, Eiki Motoyama, Mitsuru Komatsu, Yuji Takeshita, So Seryu, Haruo Kaneko

2015 2ND INTERNATIONAL CONFERENCE ON INFORMATION AND COMMUNICATION TECHNOLOGIES FOR DISASTER MANAGEMENT (ICT-DM) 186 - 192 2015

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

For some time, we have been working toward the "Realization of a Safe and Secure Society using ICT in Shiojiri-City, Nagano Prefecture." This is a project comprised of two phases: information gathering, and dissemination of information. For information gathering, we are developing systems to confirm the whereabouts of children and the elderly, who are vulnerable in disasters, and systems to gather information on the situation in mountainous regions, rivers etc. For dissemination of information, we are developing systems using broadcast technology for disseminating information to residents, such as disaster information and evacuation warnings derived from the gathered information. This presentation will describe the project goals, the background of the project thus far, and an overview of the developed system. The current situation and plans for the future will also be discussed.

Web of Science

researchmap

Behavior of trapped air in the unsaturated zone located below the water table: A secondary drainage cycle after resaturation

SAKAKI Toshihiro, KOMATSU Mitsuru

Journal of Groundwater Hydrology 56 ( 1 ) 27 - 34 2014.2

Language：Japanese Publisher：公益社団法人日本地下水学会

Fluctuations in water table height tend to generate an unsaturated zone located below the water table. It is not well understood how water saturation is affected by trapped air in this unsaturated zone. In this study, water characteristic curves for primary drainage, wetting, resaturation (under the water table), and secondary drainage cycles were measured using a one-dimensional sand-filled column. It was assumed that the pore air pressure was atmospheric and that the effect of air pressure in the discrete air bubbles could be neglected. The experimental results showed that, in the resaturation cycle, the water saturation under positive water pressure increased with water pressure and exceeded that of the water table level whereas, in the secondary drainage cycle, the saturation change was rather small indicating that the water pressure – saturation relationships in resaturation and secondary drainage cycles below the water table were irreversible. Under the conditions considered in this study, the increase of water saturation in the resaturation cycle was found to be largely controlled by the upward movement of trapped air bubbles. The obtained water retention data for the secondary drainage cycle indicated that the relationships can be affected by the maximum resaturation level that the soil has experienced. This suggests that a unique definition of the secondary drainage curve may not be appropriate when the soil has experienced resaturation.

CiNii Article

CiNii Books

researchmap

Rules-of-thumb for predicting air-entry value of disturbed sands from particle size Reviewed

Toshihiro Sakaki, Mitsuru Komatsu, Manabu Takahashi

Soil Science Society of America Journal 78 ( 2 ) 454 - 464 2014

Language：English Publishing type：Research paper (scientific journal) Publisher：Soil Science Society of America

With the goal of finding empirical direct relationships between the air-entry values (AEV) and characteristic particle diameters (i.e., d 10, d20, d30, d90,) determined from the particle-size distribution, we examined the AEV values for a variety of disturbed sands. It was found that the AEVs were, in general, strongly correlated to the characteristic diameters. The correlation was more distinct for uniform sands with uniformity coefficient of 2 or smaller. For those with larger uniformity coefficient values, the AEVs were highly correlated to smaller characteristic particle sizes d10 to d50 but less with larger characteristic particle sizes, d60 to d90. For all the sands examined in this study, the AEVs showed the least scatter when plotted against d30. The large particles do not necessarily control the AEVs because the pores between the large particles are often filled with smaller particles. The following best-fit power functions with respect to the frequently used characteristic particle diameters were found to have high r2 values
AEV = 8.2 d30 -0.99and AEV =9.5 d50 -1.05(with AEV in cm and d in mm). The exponent close to -1 in both relationships confirms a strong "inverse" proportionality. The effective pore diameter, de′, estimated from the AEVs agreed closely with the mean pore diameters measured with mercury porosimetry and X-ray micro-tomography. All these findings suggest that the AEVs are strongly controlled by the particle sizes which determine the mean pore size, and that the capillary rise theory is applicable in terms of the effective pore diameter. Finally, easy-toimplement rule-of-thumb expressions, AEV [cm] = 8/d 30[mm] and AEV [cm] =10/d50[mm] were proposed with some limitations for a quick but reasonably accurate prediction of the AEV. © Soil Science Society of America.

DOI： 10.2136/sssaj2013.06.0237n

Scopus

researchmap

What controls carbon dioxide gas phase evolution in the subsurface? Experimental observations in a 4.5 m-long column under different heterogeneity conditions Reviewed

Toshihiro Sakaki, Michael R. Plampin, Rajesh Pawar, Mitsuru Komatsu, Tissa H. Illangasekare

INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL 17 66 - 77 2013.9

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCI LTD

In order to assess the risk of CO2 leakage affecting the groundwater quality in aquifers, it is important to understand the mechanisms of CO2 gas release when brine carrying dissolved CO2 migrates to the shallow subsurface from sequestrated zones of deep geologic formations. As the brine with dissolved CO2 elevates where the water pressure is lower, development of a gas phase starts with evolution of gas out of liquid, followed by gas phase growth and movement. However, conditions under which CO2 gas evolution is triggered, how the gaseous phase CO2 migrates and/or gets entrapped in the naturally heterogeneous formations are not well understood due to the difficulties involved with obtaining detailed experimental data. In this study, our goal was to identify the conditions under which dissolved CO2 forms a gas phase and to understand how the formed CO2 gas migrates through the saturated soil formation. In particular, we put emphasis on the critical gas saturation (at which the onset of gas phase migration occurs) and how this is explained by the theoretical and modeling studies reported in the literature. We have performed a series of experiments in the laboratory using a highly instrumented long column under highly controlled conditions that are not feasible in field settings. The 4.5 m-long vertical column setup was instrumented with automated sensors to continuously monitor phase saturation, electrical conductivity (EC), temperature, and water pressure distribution along the column length as well as the rates of water and gas outflow at the upstream end of the column. The observations showed that (1) concentration of dissolved CO2 influenced the vertical extent of the gas phase formation, (2) the gas formation pattern was different if the saturation pressure was lower or higher than the static water pressure at the injection port which results largely from the gravity and viscous forces somewhat competing under the conditions in the experiments, (3) the mass transfer-dominant period where bubbles grew and water outflow increased was relatively short, (4) gas outflow was detected at the column outlet only after a continuous gas phase was formed and breakthrough had occurred, (5) the critical gas phase saturation at which the generated gas phase gets mobilized was always about 0.3-0.4 in homogeneous cases, (6) for the heterogeneous cases, a gas saturation higher than the critical gas saturation was observed due to accumulation of gas phase under a finer layer, (7) the injection rate did not affect the gas formation behavior whereas the temperature variation did, and (8) in some cases formation of gas appeared to be triggered by heterogeneities. These observations are expected to improve our understanding of gas evolution for better conceptualization and model development. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijggc.2013.03.025

Web of Science

researchmap

Behavior of trapped air in the unsaturated zone located below the water table : A slow resaturation cycle

SAKAKI Toshihiro, KOMATSU Mitsuru

Journal of Groundwater Hydrology 55 ( 3 ) 269 - 277 2013.8

Language：Japanese Publisher：公益社団法人日本地下水学会

The water characteristic curve is one of the important properties of soil required for the evaluation of groundwater flow in the unsaturated zone. Unsaturated zones occur below the water table when there is fluctuation of the water table depth. In such zones, it is not well understood how the trapped air behaves and how it affects water saturation. In this study, we estimated the water characteristic curves based on the water pressure and water saturation. The water saturation was monitored for wetting and re-saturation cycles where the water pressure was gradually increased up to 5.5 kPa using a one-dimensional sand-filled column. In the wetting cycle, the water characteristic curve was obtained assuming that the pore air pressure was atmospheric. In the re-saturation cycle, how the water characteristic curve would extend was estimated by neglecting the effect of air pressure in the discrete air bubbles. The experimental results showed that the water saturation under positive water pressure, i.e., below the water table, increased with water pressure and exceeded that at the water table level. It was concluded that the rate of increase of water saturation resulted not only from the discrete air bubbles being compressed but also being forced up as the water table gradually moved up. Not considering the increase in water saturation in the unsaturated zone below the water table could result in a significant underestimation of hydraulic conductivity in such a zone.

DOI： 10.5917/jagh.55.269

CiNii Article

CiNii Books

researchmap

Research on the ｃonstruction of an Ad-Hoc Network System for ｆlexibly ｄealing with ｄisasters Reviewed

Suzuki, H, D. K. Asano, M. Komatsu, Y. Takeshita, K. Sawada, M. Futagawa, H. Nose, Y. Fuwa

International Technical Conference on Circuits/Systems, Computers and Communications 2013 (ITC-CSCC 2013) 24 - 27 2013.7

Construction of a sensor network to forecast landslide disasters: Sensor terminal development and on-site experiments Reviewed

Hikofumi Suzuki, Daichi Kuroyanagi, David K. Asano, Mitsuru Komatsu, Yuji Takeshita, Kazuaki Sawada, Masato Futagawa, Hiroaki Nose, Yasushi Fuwa

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 7889 180 - 191 2013

Language：English Publishing type：Research paper (international conference proceedings)

We believe it is extremely important to quickly communicate information - on matters such as the extent of the damage and the safety of affected persons - when a large-scale earthquake or other disaster occurs. However, if electric power is lost, communication will be impossible with existing information networks. For this reason, we have built an Ad-Hoc network in Shiojiri City enabling communication even if electric power is lost due to a large-scale disaster. Using this Ad-Hoc network, we are building a sensor network to forecast landslide disasters. Among the various sensors installed to the sensor terminals, this paper reports in particular on observation results with EC sensors. © 2013 Springer-Verlag.

DOI： 10.1007/978-3-642-38401-1_14

Scopus

researchmap

Fabrication of a slope failure prediction sensor using miniaturized EC sensor

Masato Futagawa, Mitsuru Komatsu, Hikofumi Suzuki, Yuji Takeshita, Yasushi Fuwa, Kazuaki Sawada

IEEJ Transactions on Sensors and Micromachines 133 ( 9 ) 5 - 283 2013

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：一般社団法人電気学会

To minimize the damage caused by slope failure, knowledge of the increase in water content in mountain soil is important
however the current technology for monitoring this is insufficient. In this study, an EC sensor chip with an insulation layer with increased thickness, designed to reduce leakage current, was fabricated. Utilizing the chip, a wireless sensor terminal was constructed for long term continuous monitoring of the water content in mountain soil. The usefulness of the EC sensor for predicting slope failure was confirmed.

DOI： 10.1541/ieejsmas.133.278

Scopus

CiNii Article

researchmap

飽和砂質地盤における空気侵入値の定量的評価手法に関する研究 Reviewed

小松満, 榊利博

地盤と建設 30 ( 1 ) 39 - 46 2012.12

Developing the Soil Moisture Sensor using Optical Fiber Technique (Joint Research)

小松満, 西垣誠, 瀬尾昭治

JAEA-research 2012 ( 1 ) 1 - 77,巻頭1-2 2012.9

浅層帯水層への気体注入及びその移動現象に関する研究 Reviewed

小松満, 藤田知大, 榊利博

地盤と建設 29 ( 1 ) 27 - 37 2011.12

坑道の掘削影響に対する修復技術としてのベントナイトグラウトの適用性に関する評価 Reviewed

藪内聡, 國丸貴紀, 岸敦康, 小松満

土木学会論文集C(地圏工学) 67 ( 4 ) 464 - 473 2011.11

原位置土中水分計測による浅地層における降雨浸透量の評価方法 Reviewed

小松満, 西垣誠, 瀬尾昭治, 戸井田克, 田岸宏孝, 竹延千良, 山本陽一

地下水地盤環境に関するシンポジウム2011－水環境の保全と育水－発表論文集 17 - 29 2011.11

MONITORING OF PORE WATER PRESSURE AND WATER CONTENT AROUND A HORIZONTAL DRIFT THROUGH EXCAVATION - MEASUREMENT AT THE 140m GALLERY IN THE HORONOBE URL -

YABUUCHI Satoshi, KUNIMARU Takanori, KISHI Atsuyasu, KOMATSU Mitsuru

Journal of Japan Society of Civil Engineers, Ser. C (Geosphere Engineering) 67 ( 4 ) 464 - 473 2011

Publisher：公益社団法人土木学会

&nbsp;Japan Atomic Energy Agency has been conducting the Horonobe Underground Research Laboratory (URL) project in Horonobe, Hokkaido, as a part of the research and development program on geological disposal of high-level radioactive waste. Pore water pressure and water content around a horizontal drift in the URL have been monitored for over 18 months since before the drift excavation was started. During the drift excavation, both pore water pressure and water content were decreasing. Pore water pressure has been still positive though it continued to decrease with its gradient gradually smaller after excavation, while water content turned to increase about 6 months after the completion of the excavation. It turned to fall again about 5 months later. An unsaturated zone containing gases which were dissolved in groundwater may have been formed around the horizontal drift.

CiNii Article

researchmap

二酸化炭素の浅層帯水層への注入に関する基礎的研究 Reviewed

小松満, 藤田知大

地盤と建設 28 ( 1 ) 137 - 143 2010.12

　 PREV - NEXT 　

< KOMATSU Mitsuru >

Papers - KOMATSU Mitsuru