Fusion technology in applied geophysics

Toshifumi Matsuoka 한국암반공학회 2003 한국암반공학회 학술대회 및 세미나 자료집 Vol.- No.-

What have we learned from Nagaoka CCS project at Japan?

Toshifumi Matsuoka 한국해양환경·에너지학회 2010 한국해양환경공학회 학술대회논문집 Vol.2010 No.6

Efficacy and safety of filgotinib as induction and maintenance therapy for Japanese patients with moderately to severely active ulcerative colitis: a post-hoc analysis of the phase 2b/3 SELECTION trial

Toshifumi Hibi,Satoshi Motoya,Tadakazu Hisamatsu,Fumihito Hirai,Kenji Watanabe,Katsuyoshi Matsuoka,Masayuki Saruta,Taku Kobayashi,Brian G Feagan,Chantal Tasset,Robin Besuyen,Chohee Yun,Gerald Crans,Ji 대한장연구학회 2023 Intestinal Research Vol.21 No.1

Background/Aims: The safety and efficacy of filgotinib, a once-daily oral Janus kinase 1 preferential inhibitor, were evaluated in Japanese patients with ulcerative colitis (UC) in the phase 2b/3 SELECTION trial. Methods: SELECTION (NCT02914522) was a randomized, placebo-controlled trial comprising 2 induction studies and a maintenance study. Adults with moderately to severely active UC were randomized in induction study A (biologic-naïve) or B (biologic-experienced) to receive filgotinib 200 mg, 100 mg, or placebo once daily for 11 weeks. Patients in clinical remission or Mayo Clinic score response at week 10 entered the 47-week maintenance study. Efficacy and safety outcomes were assessed in Japanese patients enrolled in Japan. Results: Overall, 37 and 72 Japanese patients were enrolled in Japan in induction studies A and B, respectively, and 54 entered the maintenance study. Numerically higher proportions of filgotinib 200 mg-treated than placebo-treated patients achieved clinical remission in induction study A (4/15 [26.7%] vs. 0/6 [0%]) and the maintenance study (5/20 [25.0%] vs. 0/9 [0%]), but not induction study B (1/29 [3.4%] vs. 1/14 [7.1%]). Both doses were well tolerated, and no new safety signals were noted. Herpes zoster was reported in 1 filgotinib 200 mg-treated patient in each of induction study A (2.3%, 1/44) and the maintenance study (5.0%, 1/20). Conclusions: These data, alongside those of the overall SELECTION population, suggest the potential of filgotinib 200 mg as a viable treatment option for Japanese patients with UC. Owing to small patient numbers, data should be interpreted cautiously.

Acceleration of computation speed for elastic wave simulation using a Graphic Processing Unit

Nakata, Norimitsu,Tsuji, Takeshi,Matsuoka, Toshifumi Korean Society of Earth and Exploration Geophysici 2011 지구물리와 물리탐사 Vol.14 No.1

Numerical simulation in exploration geophysics provides important insights into subsurface wave propagation phenomena. Although elastic wave simulations take longer to compute than acoustic simulations, an elastic simulator can construct more realistic wavefields including shear components. Therefore, it is suitable for exploration of the responses of elastic bodies. To overcome the long duration of the calculations, we use a Graphic Processing Unit (GPU) to accelerate the elastic wave simulation. Because a GPU has many processors and a wide memory bandwidth, we can use it in a parallelised computing architecture. The GPU board used in this study is an NVIDIA Tesla C1060, which has 240 processors and a 102 GB/s memory bandwidth. Despite the availability of a parallel computing architecture (CUDA), developed by NVIDIA, we must optimise the usage of the different types of memory on the GPU device, and the sequence of calculations, to obtain a significant speedup of the computation. In this study, we simulate two- (2D) and threedimensional (3D) elastic wave propagation using the Finite-Difference Time-Domain (FDTD) method on GPUs. In the wave propagation simulation, we adopt the staggered-grid method, which is one of the conventional FD schemes, since this method can achieve sufficient accuracy for use in numerical modelling in geophysics. Our simulator optimises the usage of memory on the GPU device to reduce data access times, and uses faster memory as much as possible. This is a key factor in GPU computing. By using one GPU device and optimising its memory usage, we improved the computation time by more than 14 times in the 2D simulation, and over six times in the 3D simulation, compared with one CPU. Furthermore, by using three GPUs, we succeeded in accelerating the 3D simulation 10 times.

권두언

김정호 ( Jung Ho Kim ),( Toshifumi Matsuoka ),( James Cull ) 한국지구물리·물리탐사학회 2005 지구물리와 물리탐사 Vol.8 No.1

Random heterogeneous model with bimodal velocity distribution for Methane Hydrate exploration

Kamei Rie,Hato Masami,Matsuoka Toshifumi Korean Society of Earth and Exploration Geophysici 2005 지구물리와 물리탐사 Vol.8 No.1

We have developed a random heterogeneous velocity model with bimodal distribution in methane hydrate-bearing Bones. The P-wave well-log data have a von Karman type autocorrelation function and non-Gaussian distribution. The velocity histogram has two peaks separated by several hundred metres per second. A random heterogeneous medium with bimodal distribution is generated by mapping of a medium with a Gaussian probability distribution, yielded by the normal spectral-based generation method. By using an ellipsoidal autocorrelation function, the random medium also incorporates anisotropy of autocorrelation lengths. A simulated P-wave velocity log reproduces well the features of the field data. This model is applied to two simulations of elastic wane propagation. Synthetic reflection sections with source signals in two different frequency bands imply that the velocity fluctuation of the random model with bimodal distribution causes the frequency dependence of the Bottom Simulating Reflector (BSR) by affecting wave field scattering. A synthetic cross-well section suggests that the strong attenuation observed in field data might be caused by the extrinsic attenuation in scattering. We conclude that random heterogeneity with bimodal distribution is a key issue in modelling hydrate-bearing Bones, and that it can explain the frequency dependence and scattering observed in seismic sections in such areas.

그래픽 프로세서를 이용한 탄성파 수치모사의 계산속도 향상

( Norimitsu Nakata ),( Takeshi Tsuji ),( Toshifumi Matsuoka ) 한국지구물리·물리탐사학회 2011 지구물리와 물리탐사 Vol.14 No.1

탐사 지구물리학에서 수치 모사는 지하매질에서의 탄성파 전파 현상을 이해하는데 중요한 통찰력을 제공한다. 탄성파 모사는 음향파 근사에 의한 수치 모사보다 계산시간이 많이 소요되지만 전단응력 성분을 포함하여 보다 현실적인 파동의 모사를 가능하게 한다. 그러므로 탄성파 모사는 탄성체의 반응을 탐사하는데 적합하다고 할 수 있다. 계산 시간이 길다는 단점을 극복하기 위해 본 논문에서는 그래픽 프로세서(GPU)를 이용하여 탄성파 수치 모사 시간을 단축하고자 하였다. GPU는 많은 수의 프로세서와 광대역 메모리를 갖고 있기 때문에 병렬화된 계산 아키텍쳐에서 사용할 수 있는 장점이 있다. 본 연구에서 사용한 GPU 하드웨어는 NVIDIA Tesla C1060으로 240개의 프로세서로 구성되어 있으며 102GB/s의 메모리 대역폭을 갖고 있다. NVIDIA에서 개발된 병렬계산 아키텍쳐인 CUDA를 사용할 수 있음에도 불구하고 계산효율을 상당히 향상시키기 위해서는 GPU 장치의 여러 가지 다양한 메모리의 사용과 계산 순서를 최적화해야만 한다. 본 연구에서는 GPU 시스템에서 시간영역 유한차분법을 이용하여 2차원과 3차원 탄성파 전파를 수치 모사하였다. 파동 전파 모사에 가장 널리 사용되는 유한차분법 중의 하나인 엇갈린 격자기법을 채택하였다. 엇갈린 격자법은 지구물리학 분야에서 수치 모델링을 위해 사용하기에 충분한 정확도를 갖고 있는 것으로 알려져 있다. 본 논문에서 제안한 모델링 기법은 자료 접근 시간을 단축하기 위해 GPU 장치의 메모리 사용을 최적화하여 가능한 더 빠른 메모리를 사용한다. 이 점이 GPU를 이용한 계산의 핵심 요소이다. 하나의 GPU 장치를 사용하고 메모리 사용을 최적화함으로써 단일 CPU를 이용할 경우보다 2차원 모사에서는 14배 이상, 3차원에서는 6배 이상 계산시간을 단축할 수 있었다. 세 개의 GPU를 사용한 경우에는 3차원 모사에서 계산효율을 10배 향상시킬 수 있었다. Numerical simulation in exploration geophysics provides important insights into subsurface wave propagation phenomena. Although elastic wave simulations take longer to compute than acoustic simulations, an elastic simulator can construct more realistic wavefields including shear components. Therefore, it is suitable for exploration of the responses of elastic bodies. To overcome the long duration of the calculations, we use a Graphic Processing Unit (GPU) to accelerate the elastic wave simulation. Because a GPU has many processors and a wide memory bandwidth, we can use it in a parallelised computing architecture. The GPU board used in this study is an NVIDIA Tesla C1060, which has 240 processors and a 102GB/s memory bandwidth. Despite the availability of a parallel computing architecture (CUDA), developed by NVIDIA, we must optimise the usage of the different types of memory on the GPU device, and the sequence of calculations, to obtain a significant speedup of the computation. In this study, we simulate two- (2D) and threedimensional (3D) elastic wave propagation using the Finite-Difference Time-Domain (FDTD) method on GPUs. In the wave propagation simulation, we adopt the staggered-grid method, which is one of the conventional FD schemes, since this method can achieve sufficient accuracy for use in numerical modelling in geophysics. Our simulator optimises the usage of memory on the GPU device to reduce data access times, and uses faster memory as much as possible. This is a key factor in GPU computing. By using one GPU device and optimising its memory usage, we improved the computation time by more than 14 times in the 2D simulation, and over six times in the 3D simulation, compared with one CPU. Furthermore, by using three GPUs, we succeeded in accelerating the 3D simulation 10 times.

탄성파 및 비저항 동시측정에 의한 수포화 암석시료에 주입된 CO2모니터링 및 탐지

김종욱 ( Jong Wook Kim ),( Toshifumi Matsuoka ),설자구 ( Zi Qiu Xue ) 한국지구물리·물리탐사학회 2011 지구물리와 물리탐사 Vol.14 No.1

전기 및 탄성파 탐사를 이용한 이산화탄소 지중저장의 모니터링의 기초연구로써, 수포화 암석시료에 CO2주입시 비저항과 P파속도를 측정하였다. 암석시료는 Berea사암이며, CO2는 초임계상태(10 MPa, 40 ℃)로 주입하였다. 초임계 CO2주입에 의해 비저항의 증가 및 P파속도와 진폭이 감소하였다. P파 속도 토모그램은 암석시료에 주입한 초임계 CO2의 거동양상을 보여주었다. 비저항과 탄성파속도는 CO2거동 모니터링하는데 유용하다. 그러나 P파 속도는 비저항 변화에 비해 CO2포화도가 20% 이상 일때 변화를 보이지 않았다. 비저항으로부터 CO2포화도 예측은 탄성파 속도로부터 CO2포화도 예측의 어려움을 보완할 수 있다. 비저항과 탄성파 속도의 동시측정에 의해 암석시료에 주입한 초임계 CO2 거동 및 CO2포화도 분포를 예측할 수 있다. As part of basic studies of monitoring carbon dioxide (CO2) storage using electrical and seismic surveys, laboratory experiments have been conducted to measure resistivity and P-wave velocity changes due to the injection of CO2 into water-saturated sandstone. The rock sample used is a cylinder of Berea sandstone. CO2 was injected under supercritical conditions (10 MPa, 40℃). The experimental results show that resistivity increases monotonously throughout the injection period, while P-wave velocity and amplitude decrease drastically due to the supercritical CO2 injection. A reconstructed P-wave velocity tomogram clearly images CO2 migration in the sandstone sample. Both resistivity and seismic velocity are useful for monitoring CO2 behaviour. P-wave velocity, however, is less sensitive than resistivity when the CO2 saturation is greater than ~20%. The result indicates that the saturation estimation from resistivity can effectively complement the difficulty of CO2 saturation estimations from seismic velocity variations. By combining resistivity and seismic velocity we were able to estimate CO2 saturation distribution and the injected CO2 behaviour in our sample.

Fracture imaging using Image Point transform and midpoint imaging of RVSP data

이창현,박권규,Toshiyuki Matsuoka,Toshifumi Matsuoka 한국지질과학협의회 2010 Geosciences Journal Vol.14 No.4

An Image Point (IP) transform integrates along a hyperbolic path and converts data to a point in the IP domain so that the reflection events are accumulated to the image point for given sources in the IP domain. In addition, the image point by definition is uniquely determined and the midpoints between sources and the image points always lie on the reflector surface. Exploiting these two facts, the image point transform technique for Vertical Seismic Profile (VSP) to reverse VSP (RVSP) data is expanded to suggest a new method called the midpoint imaging method for imaging reflectors such as fractures. Applying the transform with synthetic data for Two-dimensional (2-D) models with single reflector and two reflectors, we confirm and demonstrate that the reflection events are clearly identifiable in the IP domain. The midpoint imaging method can successfully image the reflector surfaces and the dip information even with only two shot records in a simple case.

권두언

김정호 ( Jung Ho Kim ),( Kevin Dodds ),( Toshifumi Matsuoka ) 한국지구물리·물리탐사학회 2006 지구물리와 물리탐사 Vol.9 No.1