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김성협(Sunghyup KIM),古川雅人(Masato FURUKAWA),井上雅弘(Masahiro INOUE) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
Flow fields in a half ducted propeller fan have been investigated by three-dimensional Reynolds-averaged Navier-Stokes (RANS) simulations and a vortex core identification technique. The simulation at the design operating condition shows that the tip vortex onset point is located at 30 percent tip chord of the suction surface on the blade tip. There is no interaction between the tip vortex and the adjacent blade, so that the tip vortex smoothly convects to the rotor exit. However, the high vorticity in the tip vortex causes the wake and the tip leakage flow to be twined around the tip vortex and to interact with the pressure surface of the adjacent blade. This flow behavior corresponds well with experimental results by Laser Doppler Velocimetry. On the contrary, the simulation at the low-flowrate operating condition shows that the tip vortex onset point is located at the 60 percent tip chord of the suction surface. In contrast to the design operating condition, the tip vortex grows almost tangential direction, and impinges directly on the pressure surface of the adjacent blade.
Iwase, Taku,Kishitani, Tetsushi,Furukawa, Masato Korean Society for Fluid machinery 2017 International journal of fluid machinery and syste Vol.10 No.4
Flow fields in 2-blade and 4-blade half-ducted propeller fans for the outdoor units of air-conditioners were calculated with large eddy simulation based on finite element method with the aim of investigating the influence of blade number on aerodynamic noise. We confirmed that the tip vortex had a great influence on aerodynamic noise in half-ducted propeller fans. The length of the tip vortex trajectory and the blade pitch for the 2-blade propeller fan were longer than those for the 4-blade propeller fan. These were suppressed the interaction between the tip vortex and the adjacent blade in the 2-blade propeller fan.The 2-blade propeller fan was therefore more silent than the 4-blade propeller fan.
Taku Iwase,Tetsushi Kishitani,Masato Furukawa 한국유체기계학회 2017 International journal of fluid machinery and syste Vol.10 No.4
Flow fields in 2-blade and 4-blade half-ducted propeller fans for the outdoor units of air-conditioners were calculated with large eddy simulation based on finite element method with the aim of investigating the influence of blade number on aerodynamic noise. We confirmed that the tip vortex had a great influence on aerodynamic noise in half-ducted propeller fans. The length of the tip vortex trajectory and the blade pitch for the 2-blade propeller fan were longer than those for the 4-blade propeller fan. These were suppressed the interaction between the tip vortex and the adjacent blade in the 2-blade propeller fan. The 2-blade propeller fan was therefore more silent than the 4-blade propeller fan.
Takafumi Mie,Takashi Sasaki,Ryo Kanata,Takaaki Furukawa,Tsuyoshi Takeda,Akiyoshi Kasuga,Masato Matsuyama,Masato Ozaka,Naoki Sasahira 대한소화기내시경학회 2021 Clinical Endoscopy Vol.54 No.5
Background/Aims: Several fine-needle biopsy (FNB) needles are available for endoscopic ultrasound (EUS)-guided tissueacquisition. However, there is disagreement on which type of needle has the best diagnostic yield. The aim of this study was tocompare the performance and safety of two commonly used EUS-FNB needles. Methods: We retrospectively analyzed consecutive patients who underwent EUS-FNB between June 2016 and March 2020 in ourhospital. Two types of needles were evaluated: a 20-gauge Menghini needle with a lateral forward bevel and a 22-gauge Franseenneedle. Rapid on-site evaluation was performed in all the cases. A multivariate analysis was performed to clarify the negativepredictive factors for obtaining a histological diagnosis. Propensity score matching was performed to compare the diagnostic yieldsof these two needles. Results: We analyzed 666 patients and 690 lesions. The overall diagnostic rate of histology alone was 88.8%, and the overall adverseevent rate was 1.5%. Transduodenal access and small lesions (≤2 cm) were identified as negative predictive factors for obtaining ahistological diagnosis. After propensity score matching, 482 lesions were analyzed. The diagnostic accuracy rates of histology in theM and F needle groups were 89.2% and 88.8%, respectively (p=1.00). Conclusions: Both the needles showed high diagnostic yield, and no significant difference in performance was observed between thetwo.
Hideto Ueki,Takuto Hara,Yasuyoshi Okamura,Yukari Bando,Tomoaki Terakawa,Junya Furukawa,Kenichi Harada,Yuzo Nakano,Masato Fujisawa 대한비뇨의학회 2022 Investigative and Clinical Urology Vol.63 No.4
Purpose: Two methods are used to identify sarcopenia by calculating skeletal muscle area on computed tomography: the skeletal muscle index (SMI) and the psoas muscle index (PMI). Programmed death (PD)-1 inhibitors are helpful in treating metastatic renal cell carcinoma (mRCC). However, there remains insufficient information regarding a clear and easy-to-use biomarker for predicting the response to PD-1 inhibitors in patients with mRCC. Therefore, we investigated the influence of sarcopenia on clinical outcomes in patients with mRCC undergoing treatment with nivolumab. Materials and Methods: This study evaluated 96 patients with RCC who received nivolumab. The SMI and PMI were calculated for each patient and normalized for stature by use of the following formulas: SMI (cm2/m2)=([skeletal muscle cross-sectional area at the level of L3]/[height]2) and PMI (cm2/m2) = ([left-right sum of the psoas muscle areas at the level of L3]/[height]2). The relationship of the clinical variables with progression-free survival and overall survival (OS) was examined using a Cox proportional hazards model. Results: According to the SMI-based definition of sarcopenia, 74.0% of patients had sarcopenia. However, according to the PMI-based definition of sarcopenia, only 34.3% of patients were diagnosed with sarcopenia. Multivariate analysis identified sarcopenia based on PMI (hazard ratio [HR], 3.85; 95% confidence interval [CI], 2.04–7.26; p<0.001) and International Metastatic RCC Database Consortium poor risk status (HR, 1.90; 95% CI, 1.03–3.50; p=0.041) as significant and independent prognostic factors of OS. Conclusions: PMI-based sarcopenia is a significant prognostic factor for OS in patients with RCC who receive nivolumab therapy.
Tsuyoshi Takeda,Takashi Sasaki,Takafumi Mie,Takeshi Okamoto,Chinatsu Mori,Takaaki Furukawa,Yuto Yamada,Akiyoshi Kasuga,Masato Matsuyama,Masato Ozaka,Naoki Sasahira 대한소화기내시경학회 2022 Clinical Endoscopy Vol.55 No.4
Background/Aims: Digital single-operator cholangioscopy (DSOC)-guided mapping biopsy (DMB) and tube-assisted mapping biopsy(TMB) are two techniques used for preoperative evaluation of biliary tract cancer (BTC). However, data regarding the diagnostic performanceof these techniques are limited. Methods: We retrospectively examined consecutive patients with BTC who underwent either technique at our institution between2018 and 2020. We evaluated the technical success rate, adequate tissue acquisition rate, and diagnostic performance of these techniquesfor the evaluation of lateral spread of BTC. Results: A total of 54 patients were included in the study. The technical success rate of reaching the target sites was 95% for DMB and100% for TMB. The adequate tissue acquisition rate was 61% for DMB and 69% for TMB. The adequate tissue acquisition rate was low,especially for target sites beyond the secondary biliary radicles. The sensitivity of DMB alone was 39%, which improved to 65% whencombined with visual impression. Experts demonstrated a higher negative predictive value and diagnostic accuracy with respect toboth DSOC visual impression and DMB for the evaluation of lateral spread of BTC compared to trainees. Conclusions: Adequate tissue acquisition rates were similar between the two techniques. Since DMB requires expertise, TMB may bean acceptable option when DSOC is unavailable or when DSOC expertise is limited.
Takeshi Okamoto,Takashi Sasaki,Tsuyoshi Takeda,Takafumi Mie,Chinatsu Mori,Takaaki Furukawa,Yuto Yamada,Akiyoshi Kasuga,Masato Matsuyama,Masato Ozaka,Naoki Sasahira 대한소화기내시경학회 2024 Clinical Endoscopy Vol.57 No.1
Background/Aims: Selective bile duct or pancreatic duct cannulation remains a significant initial hurdle in endoscopic retrograde cholangiopancreatography (ERCP) despite advances in endoscopy and accessories. This study evaluated our experience with a rotatable sphincterotome in cases of difficult cannulation. Methods: We retrospectively reviewed ERCP cases using TRUEtome, a rotatable sphincterotome, as a rescue device for cannulation at a cancer institute in Japan from October 2014 to December 2021. Results: TRUEtome was used in 88 patients. Duodenoscopes were used for 51 patients, while single-balloon enteroscopes (SBE) were used for 37 patients. TRUEtome was used for biliary and pancreatic duct cannulation (84.1%), intrahepatic bile duct selection (12.5%), and strictures of the afferent limb (3.4%). Cannulation success rates were similar in the duodenoscope and SBE groups (86.3% vs. 75.7%, p=0.213). TRUEtome was more commonly used in cases with steep cannulation angles in the duodenoscope group and in cases requiring cannulation in different directions in the SBE group. There were no significant differences in adverse events between the two groups. Conclusions: The cannulation sphincterotome was useful for difficult cannulations in both unaltered and surgically altered anatomies. It may be an option to consider before high-risk procedures such as precut and endoscopic ultrasound-guided rendezvous techniques.
Takafumi Mie,Takashi Sasaki,Takeshi Okamoto,Tsuyoshi Takeda,Chinatsu Mori,Yuto Yamada,Takaaki Furukawa,Akiyoshi Kasuga,Masato Matsuyama,Masato Ozaka,Naoki Sasahira 대한소화기내시경학회 2024 Clinical Endoscopy Vol.57 No.2
Background/Aims: Hepaticojejunostomy anastomotic stricture (HJAS) is a feared adverse event associated with hepatopancreatobiliary surgery. Although balloon dilation for benign HJAS during endoscopic retrograde cholangiopancreatography with balloon-assisted enteroscopy has been reported to be useful, the treatment strategy remains controversial. Therefore, we evaluated the outcomes and risk factors of recurrent stenosis after balloon dilation alone for benign HJAS. Methods: We retrospectively analyzed consecutive patients who underwent balloon-assisted enteroscopy-endoscopic retrograde cholangiopancreatography for benign HJAS at our institution between July 2014 and December 2020. Results: Forty-six patients were included, 16 of whom had recurrent HJAS after balloon dilation. The patency rates at 1 and 2 years after balloon dilation were 76.8% and 64.2%, respectively. Presence of a residual balloon notch during balloon dilation was an independent predictor of recurrence (hazard ratio, 2.80; 95% confidence interval, 1.01–7.78; p=0.048), whereas HJAS within postoperative 1 year tended to be associated with recurrence (hazard ratio, 2.43; 95% confidence interval, 0.85–6.89; p=0.096). The patency rates in patients without a residual balloon notch were 82.1% and 73.1% after 1 and 2 years, respectively. Conclusions: Balloon dilation alone may be a viable option for patients with benign HJAS without residual balloon notches on fluoroscopy.