The Analysis of Output from PV Power Station to Estimate Generation Reserve for Frequency Regulation

Akatsuka, Motoki,Hara, Ryoichi,Kita, Hiroyuki,Takitani, Katsuyuki,Yamaguchi, Koji The Korean Institute of Electrical Engineers 2012 The Journal of International Council on Electrical Vol.2 No.4

As a solution for the global environmental issues and energy resource depletion issue, photovoltaic generation (PV) has been installed rapidly. However, PV generation output heavily depends on climatic conditions and it would give negative impacts on balancing between supply and demand in power systems. In order to secure the power quality, the unstable output from the natural energy resource driven generators should be considered directly in usual power system operations such as supply and demand balancing. The solar radiation forecast would take a key role in the future operation of power system; therefore, investigation of performance and its characteristics of the forecast accuracy is important. In this paper, standard deviation and time series characteristics of solar radiation forecast error are statistically estimated. This paper also develops a First-order Markov process model for solar radiation forecast error.

Awareness of Critical Thinking Attitudes and English Speaking Skills: The Effects of Questions Involving Higher-order Thinking

Yuya Akatsuka 범태평양 응용언어학회 2019 범태평양응용언어학회지 Vol.23 No.2

This study examines Japanese students’ awareness regarding critical thinking (CT) attitudes and their attention to building their speaking skills in an EFL context to determine effective CT approaches. The study began with a literature review of CiNii articles and studies from the Web of Science database regarding CT theories and educational approaches. It examined critical thinking approaches in EFL contexts as well as foreign-language approaches of International Baccalaureate® (IB) programmes. The review indicated that critical thinking can be fostered when students are asked questions that require higher-order thinking skills (HOTS) in EFL courses. Then, EFL lessons were organised based on the theories and approaches examined in the review. Participants included 22 Japanese senior high school students. Various higher cognitive level questions were posed to the participants. Additionally, students were required to prepare and present academic presentations and answer discussion questions after the presentation. To ascertain students’ awareness of attitudes toward CT, the Critical Thinking Attitudes Scale was used, and students’ reflective essays were analysed using the co-occurrence network of words in the KH Coder. To measure students’ speaking skills, their performance on speaking tasks was analysed by two International Baccalaureate’s examiners. The results indicate that the improvement of CT attitudes and speaking skills is significant regardless of English proficiency level. These findings suggest that if EFL teachers ask HOTS questions, students would become aware of critical thinking attitudes and acquire English speaking skills by answering the questions in a Japanese EFL context.

Promoting Critical Thinking Skills in an Online EFL Environment

( Yuya Akatsuka ) 범태평양 응용언어학회 2020 범태평양응용언어학회지 Vol.24 No.2

This study examined the effects of an approach that promotes EFL learners’ critical thinking in an online EFL setting. Although recent studies have examined approaches to foster EFL learners’ critical thinking, studies conducted in online settings are under-development. The participants were 31 Japanese undergraduate students enrolled in an online EFL course; their degree of critical thinking and resistance towards critical thinking were examined. First, the students’ sense of classroom community was measured using the Rovai’s Classroom Community Scale. Second, the frequency of using critical thinking in their English writing was observed adopting with Stapleton’s rubric, and the resistance towards learning critical thinking was measured through a questionnaire. The results indicated that students could feel a sense of classroom community in online lessons as well as face-to-face settings, and improvements in critical thinking were found in students’ writing regardless of the differences in their English proficiency level. A resistance towards tackling questions that required higher-order thinking was observed among low English proficiency level students compared to a face-to-face classroom setting. This study suggests that an online EFL course aiming to promote critical thinking reduce students’ resistance offering both informal and formal interactive opportunities to answer questions involving higher-order thinking skills.

Scintillation properties of GdAlO3 single crystals doped with Nd

M. Akatsuka,N. Kawaguchi,T. Yanagida 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.3

Nd-doped GdAlO3 single crystals were synthesized by the floating-zone method to evaluate their scintillation properties,particularly in the near-infrared (NIR) range. Under X-ray irradiation, scintillation due to the 4F3/2→4I11/2 transition of Nd3+was observed at 1064 nm. By changing the irradiation dose from 1 mGy-10Gy, we evaluated the relation between thescintillation intensity and the X-ray dose, and some samples showed good linearity. The scintillation decay time ranged 66-241μs due to Nd3+.

Grain size distribution and chemistry of the brackish Lake sediment in Korea

I Chan Shin,Tetsuji Akatsuka,Hisayuki Azumi,Lan Ao,Nozomi Amahashi,Maki Oyagi,Noriko Ishida,Naoshige Goto,Masahiro Maruo,Akihiko Yagi,Yashshi Seike,Seung Hyun Lee,Sung Ae Yoon,Jun Kil Choi,Young Woong 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.5

To determine the grain size distribution and chemical characteristics of bottom surface sediments in shallow brackish lagoons, we studied sediment samples collected from the entire horizontal lake area and in vertical profiles from three stations in Lakes Youngrang and Hwajinpo, on the eastern coast of Korea. Vertical and horizontal grain size distributions of the bottom sediments indicated predominantly sand- and silt in both lakes. The vertical distribution of C/N ratios ranged from 6.14 to 11.92 in Lake Youngrang, and 6.74 to 12.34 in Lake Hwajinpo. The horizontal distribution of C/N ratios in Lake Youngrang ranged from 6.1 to 17.6, whereas they ranged from 4.4 to 12.1 in Lake Hwajinpo. C/N ratios showed locally different responses to the origin of allochthonous (partial region) and autochthonous (entire region) organic materials. Horizontally, bottom sediment with low δ<SUP>13</SUP>C and high δ<SUP>15</SUP>N in Lake Youngrang were likely to be influenced by autochthonous organic material derived from primary production, and would be affected by N inputs from sources. In contrast, high δ<SUP>13</SUP>C and low δ<SUP>15</SUP>N sediments in Lake Hwajinpo were likely to be influenced by cyanobacteria.

Development of a prognostic prediction support system for cervical intraepithelial neoplasia using artificial intelligence-based diagnosis

Takayuki Takahashi,Hikaru Matsuoka,Rieko Sakurai,Jun Akatsuka,Yusuke Kobayashi,Masaru Nakamura,Takashi Iwata,Kouji Banno,Motomichi Matsuzaki,Jun Takayama,Daisuke Aoki,Yoichiro Yamamoto,Gen Tamiya 대한부인종양학회 2022 Journal of Gynecologic Oncology Vol.33 No.5

Objective: Human papillomavirus subtypes are predictive indicators of cervical intraepithelial neoplasia (CIN) progression. While colposcopy is also an essential part of cervical cancer prevention, its accuracy and reproducibility are limited because of subjective evaluation. This study aimed to develop an artificial intelligence (AI) algorithm that can accurately detect the optimal lesion associated with prognosis using colposcopic images of CIN2 patients by utilizing objective AI diagnosis. Methods: We identified colposcopic findings associated with the prognosis of patients with CIN2. We developed a convolutional neural network that can automatically detect the rate of high-grade lesions in the uterovaginal area in 12 segments. We finally evaluated the detection accuracy of our AI algorithm compared with the scores by multiple gynecologic oncologists. Results: High-grade lesion occupancy in the uterovaginal area detected by senior colposcopists was significantly correlated with the prognosis of patients with CIN2. The detection rate for high-grade lesions in 12 segments of the uterovaginal area by the AI system was 62.1% for recall, and the overall correct response rate was 89.7%. Moreover, the percentage of high-grade lesions detected by the AI system was significantly correlated with the rate detected by multiple gynecologic senior oncologists (r=0.61). Conclusion: Our novel AI algorithm can accurately determine high-grade lesions associated with prognosis on colposcopic images, and these results provide an insight into the additional utility of colposcopy for the management of patients with CIN2.

Comparison with Magnetic Resonance Three-Dimensional Sequence for Lumbar Nerve Root with Intervertebral Foramen

Hiroyuki Takashima,Tsuneo Takebayashi,Hiroki Shishido,Mitsunori Yoshimoto,Rui Imamura,Yoshihiro Akatsuka,Yoshinori Terashima,Hiroyoshi Fujiwara,Masateru Nagae,Toshikazu Kubo,Toshihiko Yamashita 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.1

Study Design: Prospective study based on magnetic resonance (MR) imaging of the lumbar spinal root of the intervertebral foramen. Purpose: This study was to compare MR three-dimensional (3D) sequences for the evaluation of the lumbar spinal root of the intervertebral foramen. Overview of Literature: The diagnosis of spinal disorders by MR imaging is commonly performed using two-dimensional T1- and T2-weighted images, whereas 3D MR images can be used for acquiring further detailed data using thin slices with multi-planar reconstruction. Methods: On twenty healthy volunteers, we investigated the contrast-to-noise ratio (CNR) of the lumbar spinal root of the intervertebral foramen with a 3D balanced sequence. The sequences used were the fast imaging employing steady state acquisition and the coherent oscillatory state acquisition for the manipulation of image contrast (COSMIC). COSMIC can be used with or without fat suppression (FS). We compared these sequence to determine the optimized visualization sequence for the lumbar spinal root of the intervertebral foramen. Results: For the CNR between the nerve root and the peripheral tissue, these were no significant differences between the sequences at the entry of foramen. There was a significant difference and the highest CNR was seen with COSMIC-FS for the intra- and extraforamen. Conclusions: In this study, the findings suggest that the COSMIC-FS sequences should be used for the internal or external foramen for spinal root disorders.