担当区分：筆頭著者,　責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japanese Geotechnical Society  

DOI： 10.3208/jgssp.v10.os-6-05

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担当区分：筆頭著者,　責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japanese Geotechnical Society  

DOI： 10.3208/jgssp.v10.ss-1-01

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Science and Business Media LLC  

The safety of buried flexible pipes is often discussed separately in terms of cross-sectional and longitudinal deformations, which can be clarified based on the circumferential and pipe axial strains, respectively. However, in modes of localized longitudinal deformation, such as differential settlement subjected to external pressure, principal strains (i.e., maximum tensile and compressive strains) on the pipe may occur in the directions different from the circumferential and axial directions. In this study, a model experiment to reproduce differential settlement was conducted using a pipe with a diameter of 300 mm, focusing on the actual damage caused by soil runoff around a buried pipe joint. In the experiment, the principal strains exerting on the pipe were calculated by measuring the strains in three directions: circumferential, axial, and intermediate. The results indicated that the principal strains in the pipe changed in the directions different from the circumferential and axial directions of the pipe owing to differential settlement, and they were approximately 1.5 times greater than the circumferential and axial strains. These results indicated the possibility of a new risk of pipe failure that cannot be captured through the strain only in a single direction (i.e., circumferential and axial pipe strains) as measured in previous studies. The results of this study are useful not only as a method to consider the behavior of a pipe deformed in cross-sectional and longitudinal directions combined, but also as a benchmark for the three-dimensional numerical analysis of buried pipes subjected to localized differential settlement.

DOI： 10.1007/s40515-022-00253-3

Web of Science

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その他リンク： https://link.springer.com/article/10.1007/s40515-022-00253-3/fulltext.html

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.1007/978-3-031-11898-2_146

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.sandf.2021.06.002

Scopus

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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担当区分：筆頭著者,　責任著者   掲載種別：研究論文（国際会議プロシーディングス）  

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掲載種別：研究論文（学術雑誌）  

© 2020 On 28th September 2018, an earthquake of Mw 7.5 hit the Central Sulawesi province in Indonesia. This was followed by liquefaction-induced large-scale ground flows in several areas in Palu city and its neighborhood. A significant characteristic of the ground flows at these sites was that large volume of soil slid downhill along gentle topographic gradients and travelled long distances (more than several hundred meters). To gain a better understanding of the fundamental mechanisms contributing to ground flows, this geo-disaster report summarizes a site investigation conducted at Sibalaya, one of the sites where massive ground flows were observed. We conducted interviews to reveal the time sequence of the event, including the main shaking that was followed by a sudden drop of the ground surface, the time at which the massive ground flow was initiated (with an extremely loud sound), as well as the change in the water level of wells. Water leakage from the unlined irrigation channel was confirmed to contribute significantly to the increase in the ground water level in this area, which thus increased the liquefaction potential. In situ tests, including eight large trench excavations and dynamic cone penetration tests, were carried out, which helped identify the liquefied and largely sheared layers. An analysis of the change in topography using satellite images and UAV photos also played an important role in capturing the overall picture of the event. Finally, a hypothesized mechanism for the extremely long slide was discussed.

DOI： 10.1016/j.sandf.2020.03.016

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.sandf.2019.11.009

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

Scopus

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

In pipe bends, unbalanced thrust force is generated depending on the internal pressure and the angle of the bend. As a new countermeasure instead of a thrust block, a lightweight thrust restraint method using gravel and geogrid has been developed. We conducted shaking table tests for a pipe bend with the lightweight thrust restraint in order to examine the effective installation conditions of the countermeasure in the fully liquefied ground. As a result, although the pipe with the thrust restraint greatly moved, the method in which gravel was backfilled inside and outside of the geogrid was effective for reducing the displacement rate of the pipe.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

Serious damage of buried pipelines is caused at the bends due to thrust force. In the current design in Japan, the sliding factor for pipelines against thrust force is determined by the passive earth pressure without considering bending angle and under two-dimensional conditions, whereas the soil failure is expected to be caused three-dimensionally. In this study, in order to clarify the uncertainty, lateral loading experiments have been conducted for model pipes. The results of the experiments show the bending angle slightly relates to the lateral resistance force and the soil failure was caused under three-dimensional conditions.

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担当区分：筆頭著者,　最終著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本地震工学会  

<p>グラベルドレーンによる液状化対策はこれまで多数の実績を有するものの, その液状化抑制効果を実際の応力レベルで実験的に検証した例は少なく, 未解明な部分が残されている．その中で, 本研究はドレーンと液状化層の透水性および有効拘束圧がドレーンによる過剰間隙水圧の消散効果に与える影響に着目し, 層厚8m相当のドレーン改良地盤を再現した遠心模型実験により検討を行った．計5ケースの実験結果から, 液状化層の透水性が高いほど, また有効拘束圧の高い液状化層の深部ほど, ドレーンによる消散効果は高まることが明らかとなった．一方で, 透水性が低く, 液状化の発生を抑制できない条件においても, 液状化の継続時間は大幅に短縮されることが確認された．</p>

DOI： 10.5610/jaee.19.6_68

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.5030/jcigsjournal.33.55

J-GLOBAL

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

J-GLOBAL

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Taylor and Francis Ltd.  

The aim of the present study is to elucidate the soil–pipe interaction in saturated sand with different effective stress. A force–displacement curve that took into account the variation of the effective stress was formulated based on the results of lateral loading experiments on a model pipe. To reproduce liquefaction experimentally, the effective stress of the soil bed was controlled by the upward seepage induced by a hydraulic gradient. The model pipe was pulled laterally under either displacement or load control. The experimental results indicate that the normalised force–displacement relationships can be well approximated by hyperbolic curves under each hydraulic gradient. When the variation in effective stress is reflected in the submerged unit weight of the soil, the two coefficients of the hyperbolic curves also show a hyperbolic dependence on the unit weight, and the ultimate resistive force increases in proportion to the unit weight. The predicted force–displacement curve fits relatively well to the experimental results.

DOI： 10.1080/19386362.2017.1288356

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer US  

Two-dimensional simulation was carried out using a fluid coupled-DEM (discrete element method) analysis on lateral loading experiments for a pipe buried in saturated sand. The interaction between soil and pore water was reproduced by dividing the model into solid and fluid phases. The variation of the excess pore water pressure was calculated on a fluid mesh based on the pore volume change and was then given to the soil particles in the solid phase. The head difference between the fluid meshes produced upward seepage to the soil model. Liquefaction was reproduced by the decrease of the contact force between the soil particles due to the upward seepage. The force-displacement curves obtained from lateral loading simulations showed good agreement with the experimental results under various effective stress conditions. Distribution maps of contact force and displacement of soil particles revealed displacement mechanism of the buried pipe and its surrounding soil. The variation of the void ratio and the excess pore water pressure with the pipe displacement could be reproduced to some extent, and the applicability of this analysis method to interaction problems has been verified.

DOI： 10.1007/s40515-018-0050-5

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掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：International Society of Ocean and Polar Engineering  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ASCE  

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担当区分：筆頭著者,　責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.11408/jsidre.85.I_29

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：American Society of Civil Engineers (ASCE)  

A series of lateral loading experiments were conducted for a model pipe buried in saturated sand to obtain the relationships between the lateral resistive force and lateral displacement of the pipe. The model pipe was pulled laterally by an actuator after the effective stress of the soil bed was controlled by the upward seepage induced by a hydraulic gradient. The experimental results showed that the lateral resistive force increased non-linearly with the lateral displacement of the pipe. The relationship between the ultimate resistive force and the hydraulic gradient was linear. The force-displacement relationships were well approximated by hyperbolic curves under each hydraulic gradient. The relationships between the coefficients of the hyperbolic curve and hydraulic gradient were also approximated nonlinearly as hyperbolic curves.

DOI： 10.1061/9780784480878.005

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：国際ジオシンセティックス学会日本支部  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：AMER SOC CIVIL ENGINEERS  

Trenchless rehabilitations have often been used for repairing aging irrigation pipes. However, in the Japanese design standard for irrigation pipes, the design of the rehabilitations is not prescribed. Many of past studies have not dealt with the mechanical behavior of rehabilitated pipes under eccentric loading, and the behavior has not been understood. In this study, for investigating the mechanical behavior of the rehabilitated pipes under eccentric loading, model experiments and FE-analyses were conducted. In the experiments, the rehabilitated pipes were modeled by placing the aluminum segments around the polyvinyl chloride (PVC) pipes, and the pipes were loaded with the air-bag. The results indicated that the only liners under eccentric loading deformed in oblique directions with the shift of the loading positions. On the other hand, the deformations of the liners with the host pipes were dependent on both the directions of loads acting on the liners and the damage states of the host pipes.

Web of Science

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掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s40515-016-0030-6

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：American Society of Civil Engineers (ASCE)  

In Japan, a sheet-pile method is often used to install pipelines with large diameter into the ground because of narrow work sites and high groundwater levels. However, voids develop in the ground associated with the extraction of sheet-piles. Therefore, the ground around the buried pipes rapidly deforms, and the earth pressure acting on the pipes changes. In this paper, in order to investigate the mechanical behavior of the buried pipe during sheet-pile extraction, two-dimensional analyses by discrete element method were conducted. In this analysis, sheet-piles with three kinds of embedded length was installed, and flexible pipe having diameter of 1.0 m was modeled and backfilled in sand or cohesive soil. The result of the analyses indicated that the sheet-pile extraction led to the development of a loose area in the ground. The loose area resulted in settlement and deflection of the flexible pipe. Especially in the case of cohesive soil, the settlement and deflection were larger than expected.

DOI： 10.1061/9780784479957.112

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掲載種別：研究論文（学術雑誌）  

In Japan, a trenchless rehabilitation method has often been used for replacing aging irrigation pipes because of the economical reason. With the method, damaged host pipes are repaired with new pipes. Namely, the rehabilitated pipeline system comprises two pipes: a damaged host pipe and a liner. The mechanical behavior of liners is influenced by host pipes. In the present study, in order to reveal the mechanical behaviors, centrifuge model tests were carried out under various conditions including the damage levels of the host pipe, the positions of surcharge load, the ring stiffness of the liner, and the stiffness of the backfill. Test results indicate that the deflection of the liner increases with the damage level of the host pipe, and the influence of the host pipe on the liner is negligible when the host pipe reaches the ultimate damaged state. In addition, the strain concentration occurs at the crown of the inner due to the contact between the edge of the damaged host pipe and the liner. The strain concentration is reduced by 20 % with the increase of the ring stiffness of the liner. It is also revealed that the strain concentration appears even if the stiffness of backfills increases.

DOI： 10.1007/s40515-015-0023-x

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：American Society of Civil Engineers (ASCE)  

In Japan, the main irrigation pipeline network is increasingly getting older and losing its function due to deterioration. The concept of in-situ rehabilitation for aging pipelines, which can improve the performance of a damaged pipe by installing new pipeline inside of the existing aging pipeline, has gained increasing attention. However, the seismic mechanical behavior of pipeline rehabilitated by this method is not substantially clear. In this study, to clarify the effect of damaged outer pipe on the inner pipe, shaking table tests were conducted for the buried pipe in liquefied ground. To model the inner pipe, polyvinyl-chloride (PVC) and polyethylene (PE) pipe were used. To model the outer aging pipe, different types of concrete pipes in length were used. The test results indicated that the amplitude of the bending strain in PVC pipe sharply increased due to the stress concentration at the gap between outer pipes. Additionally, the deflection mode of the pipe was categorized into two main types
bow-shaped deformation and pendulum-shaped deformation.

DOI： 10.1061/9780784479360.030

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：農業農村工学会  

近年，耐用年数を迎える農業用管路の増加に伴い，非開削での施工が可能な管路更生工法の採用が進展している。しかしながら，更生管の力学挙動は未解明で，設計手法も確立されていない現状にある。更生工法では，老朽化した既設管を撤去せずに管路を更新するため，半永久的に更生管外周に既設管が残存する。本研究では，既設管損傷レベルと荷重条件を変化させた土中埋設実験を実施し，既設管が更生管力学挙動に与える影響について検討した。その結果，既設管損傷レベルの進行に伴い，更生管のたわみが増大することが明らかになった。また，損傷状態によっては，既設管と更生管が点接触することで，局所的に卓越したひずみが発生することがわかった。さらに，地表面偏心荷重の場合，ひずみが卓越する箇所が損傷レベルにより異なることが明らかになった。

CiNii Books

CiNii Research

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：American Society of Civil Engineers (ASCE)  

This paper discusses an experimental study on the pipe rehabilitation method for the purpose of establishing a fundamental design standard. In this method, as the new pipe is directly inserted into the aging pipe, there are several possibilities in terms of cost reduction. It is not clear how the damaged outer pipe mechanically influences the inner pipe through interaction with the surrounding soil when an external force is applied to the ground. In this study, centrifuge model tests for the buried pipe are carried out. The test results indicated that deformation mode of the new pipe largely depends on the damage level of the outer pipe. When the damage state is not serious, the outer pipe protects the inner pipe from deforming and behaves positively. However, the outer pipe, if at ultimate limit state, has almost no influence on the mechanical behavior of the inner pipe. Additionally, the concentration of stress within the inner pipe tends to occur at the position where there is cracking of the outer pipe in a certain damaged condition. © 2014 American Society of Civil Engineers.

DOI： 10.1061/9780784413692.094

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

The purpose of this study is to clarify how the damaged old pipe affects the inner rehabilitated pipe in the ground. Using some model pipes which have several damage levels, vertical loading test for buried pipe was conducted. As a result of this experiment, it was found that the stress concentration was occurred on the rehabilitated pipe by the edge of damaged old pipe. In addition, it was clarified that the inner circumferential strains occurred on the rehabilitated pipe was noticeably different depending on the damage level of the deteriorating old pipe. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE).

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：シンポジウム・ワークショップ パネル（指名）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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会議種別：シンポジウム・ワークショップ パネル（指名）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：英語   会議種別：口頭発表（一般）  

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会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：口頭発表（一般）  

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会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：英語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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会議種別：口頭発表（招待・特別）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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会議種別：口頭発表（一般）  

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記述言語：日本語   会議種別：口頭発表（一般）  

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