Effect of a dynamic absorber on friction-induced vibration of a rectangular plate

Hiroki Mori,Oleksandr Mikhyeyev,Takuo Nagamine,Mizue Mori,Yuichi Sato 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.1

When a plate-like object is rubbed by rubber, friction-induced vibration is generated. To reduce the friction-induced vibration, we experimentally investigate the characteristics of the vibration of a rectangular glass plate. The results show that the frequency of the frictioninduced vibration is almost the same as the natural frequency of a glass plate. The vibration is generated when the natural frequency of a rubbing system is close to that of a glass plate. We then examine the effect of a dynamic absorber mounted on the glass plate. The results demonstrate that the damping of a dynamic absorber is effective for suppressing the friction-induced vibration. Numerical simulation is also performed using a simplified analytical model. The calculated results agree qualitatively with the experimental ones.

Analysis of popliteal artery location for high tibial and distal tuberosity osteotomy using contrast-enhanced computed tomography

( Akiyoshi Mori ),( Takehiko Matsushita ),( Nobuaki Miyaji ),( Kanto Nagai ),( Daisuke Araki ),( Noriyuki Kanzaki ),( Tomoyuki Matsumoto ),( Takahiro Niikura ),( Yuichi Hoshino ),( Ryosuke Kuroda ) 대한슬관절학회 2022 대한슬관절학회지 Vol.34 No.-

Background: Our objective was to evaluate the location of popliteal artery (PA) in osteotomy planes during high tibial osteotomy (HTO) and to determine a safer angle for screw drilling to the tibial tuberosity during distal tuberosity osteotomy (DTO). Methods: Twenty knees in 20 patients who underwent contrast-enhanced computed tomography for cardiovascular diseases were examined. Osteotomy planes for open-wedge HTO (OWHTO) and hybrid closed-wedge HTO (hybrid CWHTO) were created using three-dimensional bone models. The distance from the posterior cortex of the tibia to the PA (dPC-PA) in the osteotomy planes was measured in the virtual osteotomy planes. The dangerous point (Point D1) was defined as the point 17.5 mm away from PA, setting the working length of the bone saw as 35 mm. The distance between the most medial point of the tibial cortex (Point M) and Point D1 in OWHTO and the most lateral point (Point L) and Point D1 in hybrid CWHTO were examined (dM-D1 and dL-D1, respectively). The location of Point D1 to the osteotomy line (%D1) was expressed as percentage, setting the start and end of the osteotomy line as 0% and 100%, respectively. To determine the safe angle for screw drilling in DTO, the angle between the line tangential to the medial cortex of the tibia and that passing through the center of the tibial tuberosity and PA were measured. Results: In OWHTO and hybrid CWHTO, the mean dPC-PA was 10.6 mm (6.9-16.5 mm) and 10.2 mm (7.3-15.4 mm), respectively. The mean dM-D1 in OWHTO was 25.9 mm (24.6-27.2 mm) and dL-D1 in hybrid CWHTO was 5.1 mm (2.9-7.4 mm). The mean %D1 was 47.6 ± 3.7% in OWHTO and 9.3 ± 4.1% in hybrid CWHTO, respectively. The minimal angle between the two lines in DTO was 35.2°. Conclusion: PAs could run within 10 mm from the posterior cortex in the osteotomy planes of HTO. Therefore, proper posterior protection is necessary when cutting posterior cortex. An angle of less than 35° against the medial cortex line would be safe for screw fixation to avoid vascular injury in DTO.

Computer-aided polyp characterization in colonoscopy: sufficient performance or not?

Natalie Halvorsen,Yuichi Mori 대한소화기내시경학회 2024 Clinical Endoscopy Vol.57 No.1

Computer-assisted polyp characterization (computer-aided diagnosis, CADx) facilitates optical diagnosis during colonoscopy. Several studies have demonstrated high sensitivity and specificity of CADx tools in identifying neoplastic changes in colorectal polyps. To implement CADx tools in colonoscopy, there is a need to confirm whether these tools satisfy the threshold levels that are required to introduce optical diagnosis strategies such as “diagnose-and-leave,” “resect-and-discard” or “DISCARD-lite.” In this article, we review the available data from prospective trials regarding the effect of multiple CADx tools and discuss whether they meet these thresholds.

Microstructure Control of Grain-oriented Barium-titanate Ceramics and Their Piezoelectric Properties

Petr Pulpan,Rintaro Mori,Hiroshi Hayashi,Yoshitaka Nagamori,Yuichi Yamamoto,Satoshi Wada 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.41

A templated grain growth (TGG) method was used for the preparation of grain-oriented bariumtitanate (BaTiO3, BT) ceramics. [110]-oriented BT plate-like template particles were dispersed in a matrix of hydrothermal BT spherical particles of various sizes. The Lotgering method using the Xray diffraction (XRD) pattern determined the degree of orientation along the [110] direction (F110). An optimization of the preparation conditions was performed in terms of the template-to-matrix weight ratio (T/M), the Ba/Ti ratio, and the sintering temperature and time in order to achieve a high F110 along with a small grain size and a high density. A grain size as small as 10 µm could be reached for Ba/Ti ratios close to the stoichiometric value. Lower values led to an increase in F110 and in the grain size. A T/M bigger than 80% was necessary for F110 to be above 80% and for the grain size lower than 40 µm. The density was almost independent of the T/M and the Ba/Ti ratios. The grain growth was limited by a two-step sintering process. Small grain size, high F110 and high density are essential if the piezoelectric constant d33 is to be increased above the values for standard BT ceramics.

Risk Stratification of T1 Colorectal Cancer Metastasis to Lymph Nodes: Current Status and Perspective

( Katsuro Ichimasa ),( Shin-ei Kudo ),( Hideyuki Miyachi ),( Yuta Kouyama ),( Masashi Misawa ),( Yuichi Mori ) 대한간학회 2021 Gut and Liver Vol.15 No.6

With the widely spreading population-based screening programs for colorectal cancer and recent improvements in endoscopic diagnosis, the number of endoscopic resections in subjects with T1 colorectal cancer has been increasing. Some reports suggest that endoscopic resection prior to surgical resection of T1 colorectal cancer has no adverse effect on prognosis and contributes to this tendency. The decision on the need for surgical resection as an additional treatment after endoscopic resection of T1 colorectal cancer should be made according to the metastasis risk to lymph nodes based on histopathological findings. Because lymph node metastasis occurs in approximately 10% of patients with T1 colorectal cancer according to current international guidelines, the remaining 90% of patients may be at an increased risk of surgical resection and associated postoperative mortality, with no clinical benefit derived from unnecessary surgical resection. Although a more accurate prediction system for lymph node metastasis is needed to solve this problem, risk stratification for lymph node metastasis remains controversial. In this review, we focus on the current status of risk stratification of T1 colorectal cancer metastasis to lymph nodes and outline future perspectives. (Gut Liver 2021;15:818-826)

Clinical Efficacy of Endocytoscopy for Gastrointestinal Endoscopy

Masashi Misawa,Shin-ei Kudo,Yuki Takashina,Yoshika Akimoto,Yasuharu Maeda,Yuichi Mori,Toyoki Kudo,Kunihiko Wakamura,Hideyuki Miyachi,Fumio Ishida,Haruhiro Inoue 대한소화기내시경학회 2021 Clinical Endoscopy Vol.54 No.4

Endocytoscopy (EC) is a contact-type optical endoscope that allows in vivo cellular observation during gastrointestinal endoscopyand is now commercially available not only in Japan but also in Asian, European Union, and Middle Eastern countries. EC helpsconduct a highly accurate pathological prediction without biopsy. Initially, EC was reported to be effective for esophageal diseases. Subsequently, its efficacy for stomach and colorectal diseases has been reported. In this narrative review, we searched for clinicalstudies that investigated the efficacy of EC. EC seems to accurately diagnose gastrointestinal diseases without biopsy. Most of thestudies aimed to clarify the relationship between endocytoscopic findings of gastrointestinal neoplasia and pathological diagnosis. Some studies have investigated non-epithelial lesions or diseases, such as inflammatory bowel disease or infectious diseases. However, there are few high-level pieces of evidence, such as randomized trials; thus, further studies are needed.