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Nakamura, Junichi,Makishima, Akihito,Umehara, Daisuke,Kawai, Makoto 통신위성우주산업연구회 2002 Joint Conference on Satellite Communications Vol.2002 No.-
TCP is generally used for data transmission on a geo-synchronous satellite link. It is known that the throughput increase corresponding to the increase of transmission speed can not be expected on a geo-synchronous satellite link since TCP was originally designed as a protocol for terrestrial cable networks. We established a computer simulation system and an experimental system using a Ka-band satellite to investigate the TCP performance on a high speed satellite communication link. This paper describes the throughput performances obtained by both systems using Window Scaling Option which is expected to improve the conventional TCP performances and shows the relationship between bit error rate and throughput.
Experimental and numerical flow analysis in hydraulic vane pump
Junichi SUEMATSU,Tetsuhiro TSUKIJI,Mariko WATANABE,Shinji YAKABE,Hirohito WATANABE,Yoshinari NAKAMURA,Kazunari SUZUKI 유공압건설기계학회 2015 유공압건설기계학회 학술대회논문집 Vol.2015 No.10
The purpose of this study is to conduct a three dimensional flow analysis of a hydraulic vane pump by using computational fluid dynamics (CFD), to evaluate an accuracy of volumetric flow rate in CFD compared to experimental value and to examine a influence of the evaporation coefficient and condensation coefficient in Zwart–Gerber–Belamri cavitation model to pressure in a vane chamber. In this study, standard k-ε turbulent model with the Zwart–Gerber–Belamri cavitation model is used to estimate the cavitating flow in vane pump. In CFD, two notch models are used. From results of experiments and CFD analysis of volumetric flow rate, there is little difference between the experiments and CFD results in the low speed range. However, for high speed range, in a case with no cavitation model, the CFD results of volumetric flow rate are different from the experimental ones. On the other hand, in the case with cavitation model, those agree with the experimental values. In this case, the error of volumetric flow rate is less than 1% in the low speed range and less than 2.5% in the high speed range. From CFD results of pressure fluctuation in a vane chamber when the evaporation coefficient and condensation coefficient in the cavitation model are varied, the surge pressure can be seen in a vane chamber. In conclusion, it could be considered that the CFD calculation with cavitation model is sufficiently accurate in volumetric flow rate. In addition, as the evaporation coefficient becomes large, amplitude of the pressure fluctuation in a vane chamber after a surge pressure becomes large, as the condensation coefficient becomes large, the surge pressure in a vane chamber becomes low.
Takashi Yokoyama,Masaru Nakamura,Junichi Tatami,Toru Wakihara,Takeshi Meguro 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.5
Preparation of cubic spinel-type oxides, Mn(1.75−1.25X)Co2.5XNi1.25(1−X)O4 (0 ≤X≤ 0.6), and their electrical properties were investigated. The starting oxides, containing metals with a prescribed molar ratio, were heated to 1400℃ and held for 3 h in argon. The sintered bodies were cooled to 800 oC and then oxidized for 48 h in air to convert them into a cubic spinel structure. The electrical conductivities of the sintered bodies were confirmed to increase exponentially with an increase in the temperature, indicating that they have intrinsic NTC thermistor characteristics. In the region of 0 ≤ X≤ 0.4, the electrical conductivity increased with an increase in X and decreased with an increase in X in the region of 0.4 < X ≤ 0.6. The concentration of Mn4+ in the octahedral sites of the spinel structure was considered to be larger than that of Mn3+ because the sintered bodies were n-type semiconducting. The electrical conduction of the oxides prepared in this study was concluded to be controlled by a small polaron hopping mechanism. Preparation of cubic spinel-type oxides, Mn(1.75−1.25X)Co2.5XNi1.25(1−X)O4 (0 ≤X≤ 0.6), and their electrical properties were investigated. The starting oxides, containing metals with a prescribed molar ratio, were heated to 1400℃ and held for 3 h in argon. The sintered bodies were cooled to 800 oC and then oxidized for 48 h in air to convert them into a cubic spinel structure. The electrical conductivities of the sintered bodies were confirmed to increase exponentially with an increase in the temperature, indicating that they have intrinsic NTC thermistor characteristics. In the region of 0 ≤ X≤ 0.4, the electrical conductivity increased with an increase in X and decreased with an increase in X in the region of 0.4 < X ≤ 0.6. The concentration of Mn4+ in the octahedral sites of the spinel structure was considered to be larger than that of Mn3+ because the sintered bodies were n-type semiconducting. The electrical conduction of the oxides prepared in this study was concluded to be controlled by a small polaron hopping mechanism.
( Yasunori Yamamoto ),( Shinya Furukawa ),( Teruki Miyake ),( Junichi Watanabe ),( Yukihiro Nakamura ),( Yoshihiro Taguchi ),( Tetsuya Yamamoto ),( Aki Kato ),( Katsunori Kusumoto ),( Osamu Yoshida ) 대한소화기기능성질환·운동학회 2024 Journal of Neurogastroenterology and Motility (JNM Vol.30 No.2
Background/Aims Although certain allergic diseases have been reported to be associated with the prevalence of functional dyspepsia (FD) and irritable bowel syndrome (IBS), it is unclear whether the presence of multiple allergic diseases further increases the prevalence of FD and IBS. The aim of this study is to determine this issue in young people. Methods A cohort of 8923 Japanese university students was enrolled and diagnoses of FD and IBS were confirmed using Rome III criteria. Allergic disorders diagnosed at medical institutions were obtained by means of a self-administered questionnaire. Results The prevalence of FD, IBS, and their overlap was found to be 1.9%, 6.5%, and 1.1%, respectively. Pollen allergy was independently positively correlated with FD, IBS, and overlap of FD and IBS. Allergic rhinitis was positively linked to IBS. Drug allergy was positively associated with FD. The presence of multiple allergic diseases was positively correlated with FD and IBS (FD: adjusted OR for 2 allergic diseases: 1.95 [95% CI, 1.24-2.98], P for trend = 0.003; and IBS: adjusted OR for 1 allergic disease: 1.40 [95% CI, 1.15- 1.69], 2 allergic diseases 1.47 [95% CI, 1.12-1.91], and 3 or more allergic diseases: 2.22 [95% CI, 1.45-3.28], P for trend = 0.001). Additionally, the concomitant existence of multiple allergic diseases was also demonstrated to have a trend that correlated with the overlap of FD and IBS (P for trend = 0.018). Conclusion Allergic disease multimorbidity is positively correlated with the prevalence of FD and IBS in a young population. (J Neurogastroenterol Motil 2024;30:229-235)
Seiji Ohtori,Takeshi Sainoh,Masashi Takaso,Gen Inoue,Sumihisa Orita,Yawara Eguchi,Junichi Nakamura,Yasuchika Aoki,Tetsuhiro Ishikawa,Masayuki Miyagi,Gen Arai,Hiroto Kamoda,Miyako Suzuki,Gou Kubota,Yos 연세대학교의과대학 2012 Yonsei medical journal Vol.53 No.2
Purpose: Sacroiliac fixation using iliac screws for highly unstable lumbar spine has been reported with an improved fusion rate and clinical results. On the other hand, there is a potential for clinical problems related to iliac fixation, including late sacroiliac joint arthritis and pain. Materials and Methods: Twenty patients were evaluated. Degenerative scoliosis was diagnosed in 7 patients, failed back syndrome in 6 patients, destructive spondyloarthropathy in 4 patients, and Charcot spine in 3 patients. All patients underwent posterolateral fusion surgery incorporating lumbar, S1 and iliac screws. We evaluated the pain scores, bone union, and degeneration of sacroiliac joints by X-ray imaging and computed tomography before and 3 years after surgery. For evaluation of low back and buttock pain from sacroiliac joints 3 years after surgery, lidocaine was administered in order to examine pain relief thereafter. Results: Pain scores significantly improved after surgery. All patients showed bone union at final follow-up. Degeneration of sacroiliac joints was not seen in the 20 patients 3 years after surgery. Patients showed slight low back and buttock pain 3 years after surgery. However, not all patients showed relief of the low back and buttock pain after injection of lidocaine into the sacroiliac joint, indicating that their pain did not originate from sacroiliac joints. Conclusion: The fusion rate and clinical results were excellent. Also, degeneration and pain from sacroiliac joints were not seen within 3 years after surgery. We recommend sacroiliac fixation using iliac screws for highly unstable lumbar spine.
Seiji Ohtori,Sumihisa Orita,Kazuyo Yamauchi,Yawara Eguchi,Yasuchika Aoki,Junichi Nakamura,Masayuki Miyagi,Miyako Suzuki,Gou Kubota,Kazuhide Inage,Takeshi Sainoh,Jun Sato,Yasuhiro Shiga,Koki Abe,Kazuki 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.3
Study Design: Retrospective case series. Purpose: To determine whether symptoms predict surgical outcomes for patients with discogenic low back pain (DLBP). Overview of Literature: Specific diagnosis of DLBP remains difficult. Worsening of pain on flexion is a reported symptom of DLBP. This study sought to determine whether symptoms predict surgical outcomes for patients with DLBP. Methods: We investigated 127 patients with low back pain (LBP) and no dominant radicular pain. Magnetic resonance imaging was used to select patients with disc degeneration at only one level. If pain was provoked during discography, we performed fusion surgery (87 patients). Visual analogue scale score and responses to a questionnaire regarding symptoms including worsening of pain on flexion or extension were assessed. Symptom sites before surgery were categorized into LBP alone, or LBP plus referred inguinal or leg pain. We followed 77 patients (average 3.0 years) and compared symptoms before surgery with surgical outcome. Results: Sixty-three patients with a good outcome showed postsurgical pain relief (≥60% pain relief) and 14 patients with a poor outcome did not (<60% pain relief). In patients with good outcomes, worsening of LBP was evident in 65% of cases on flexion and in 35% on extension. However, these findings were not significantly different from those in patients with poor outcomes. The percentage of patients with LBP alone was significantly lower and the percentage of patients with LBP plus referred inguinal or leg pain was significantly higher in the group with good surgical outcome compared with patients in the group with poor surgical outcome (p <0.05). Conclusions: Worsening of pain on extension may be a symptom of DLBP. Surgical outcomes were superior in patients with both LBP and either referred inguinal or leg pain compared with those having LBP alone.
Efficacy of TachoSil, a Fibrin-Based Hemostat, for Anterior Lumbar Spine Surgery
Jo Watanabe,Seiji Ohtori,Sumihisa Orita,Kazuyo Yamauchi,Yawara Eguchi,Yasuchika Aoki,Junichi Nakamura,Miyako Suzuki,Kazuhide Inage,Jun Sato,Yasuhiro Shiga,Koki Abe,Kazuki Fujimoto,Hirohito Kanamoto,Ei 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.5
Study Design: Retrospective case series. Purpose: To examine the efficacy of TachoSil for vessel injury in 6 patients who underwent anterior lumbar fusion surgery (ALF). Overview of Literature: ALF for the lumbar spine has a high rate of success, although intraoperative concerns and iatrogenic complications are known, and injury of a major vessel is sometimes a complication. The efficacy of TachoSil, a fibrin-based hemostat, has been reported for several types of surgery; however, use of TachoSil for ALF surgery has not been described. Here, we report on the efficacy of TachoSil in 6 patients, who underwent ALF after vascular surgeons having difficulty in repairing vessels. Methods: Two man and 4 women with average age of 50.8±10.9 (mean±standard deviation) were diagnosed with a vertebral tumor (2 patients), L4 degenerative spondylolisthesis (2 patients), and L5 spondylolytic spondylolisthesis (2 patients) and underwent ALF. The blood vessels injured included the common iliac vein in 2 patients and a branch of a segmental artery from the aorta in 4 patients. We consulted a vascular surgeon to suture or repair the vessels during surgery, and although the vascular surgeon attempted to address the injuries, suturing or repair was not possible in these cases. For this reason, we used TachoSil to repair the injury in the vessels walls or to stop the bleeding. Results: Time to pressure hemostasis using TachoSil was 34±12 minutes, and total blood loss was 1,488±1,711 mL. Nevertheless, all vessel injuries were controlled by the use of TachoSil. Conclusions: We recommend the use of TachoSil for vessel injuries that vascular surgeons cannot suture or repair during ALF surgery.