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Current status of the diagnosis of chronic pancreatitis by ultrasonographic elastography
( Kazunori Nakaoka ),( Senju Hashimoto ),( Ryoji Miyahara ),( Hiroki Kawashima ),( Eizaburo Ohno ),( Takuya Ishikawa ),( Takamichi Kuwahara ),( Hiroyuki Tanaka ),( Yoshiki Hirooka ) 대한내과학회 2022 The Korean Journal of Internal Medicine Vol.37 No.1
Chronic pancreatitis (CP) is pathologically characterized by the loss of exocrine pancreatic parenchyma, irregular fibrosis, cellular infiltration, and ductal abnormalities. Diagnosing CP objectively is difficult because standard diagnostic criteria are insufficient. The change of parenchymal hardness is the key factor for the diagnosis and understanding of the severity of CP. The ultrasonography (US) or endoscopic ultrasonography (EUS) elastography have been used to diagnose pancreatic diseases. Both strain elastography (SE) and shear wave elastography are specific diagnostic techniques for measuring tissue hardness. Most previous studies were conducted with SE. There are three methods of interpreting SE; the method of recognizing the patterns in SE distribution images in the region of interest, the method of using strain ratio to compare the hardness of adipose tissue or connective tissue with that of the lesion, and the method of evaluating the hardness distribution of a target by histogram analysis. These former two methods have been used primarily for neoplastic diseases, and histograms analysis has been used to assess hardness distribution in the evaluation of CP. Since the hardness of the pancreas increases with aging, it is necessary to consider the age in the diagnosis of pancreatic disorders using US or EUS elastography.
Kazunori Nishimura,Katsuya Hirachi,Eiji Hiraki,Nabil A. Ahmed,Hyun Woo Lee,Mutsuo Nakaoka 전력전자학회 2006 JOURNAL OF POWER ELECTRONICS Vol.6 No.4
This paper presents an improved three-phase PFC power rectifier with a three-phase diode rectifier cascaded four-switch boost converter. Its operating principle contains the operating principle of two conventional three-phase PFC power rectifiers: one switch boost converter type and a two switch boost converter type. The operating characteristics of the four switch boost converter type three-phase PFC power rectifier are evaluated from a practical point of view, being compared with one switch boost converter type and two switch boost converter topologies.
Kazunori Suzuoka,Sergey Moiseev,Yoshinori Ishigami,Keiki Morimoto,Yuji Yoshizako,Yoshiki Fukumoto,Hyun Woo Lee,Mutsuo Nakaoka 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
This paper presents a novel circuit topology of a voltage source type zero voltage soft-switching (ZVS) full bridge inverter linked DC-DC power converter with a high frequency transformer, which incorporates zero current soft-switching (ZCS) phaseshift PWM controlled active power switches in series either right or left leg in its full-bridge diode passive rectifier of a transformer secondary-side and transformer parasitic inductors. It is noted that the DCDC power converter treated here can achieve softswitching commutation under wide load variations from an extremely light load to a heavy load as well as a condition of a constant frequency phase-shift PWM voltage regulation strategy in transformer secondary side. Its operating principle in steady state is described, together with some unique features. The practical effectiveness of this softswitching DC-DC power converter with a high frequency isolation link is proven on the basis of simulation and experimental results.
Nishimura Kazunori,Hirachi Katsuya,Hiraki Eiji,Ahmed Nabil A.,Lee Hyun-Woo,Nakaoka Mutsuo The Korean Institute of Power Electronics 2006 JOURNAL OF POWER ELECTRONICS Vol.6 No.4
This paper presents an improved three-phase PFC power rectifier with a three-phase diode rectifier cascaded four-switch boost converter. Its operating principle contains the operating principle of two conventional three-phase PFC power rectifiers: one switch boost converter type and a two switch boost converter type. The operating characteristics of the four switch boost converter type three-phase PFC power rectifier are evaluated from a practical point of view, being compared with one switch boost converter type and two switch boost converter topologies.
권순걸,Bishwajit Saha,문상필,Kazunori Nishimura,Mutsuo Nakaoka 전력전자학회 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.1
Conventional series-resonant pulse frequency modulation controlled DC-DC high power converters with a high-frequency transformer link which is designed for driving the high power microwave generator has the problem of hard switching commutation at turn-on and turn-off of active power switching devices. This problem is due to the influence of the magnetizing current of the high-frequency transformer. This paper presents a novel prototype for a high-frequency transformer using parasitic parameters with a lossless inductive snubber and a series resonant capacitor assisted series-resonant zero current switching pulse frequency modulated DC-DC power converter, which is designed using a high power magnetron for microwave ovens. In order to implement a complete and efficient soft switching commutation, the performance of the new converter topology is practically confirmed and evaluated in the prototype of a power microwave generator.
Soon-Kurl Kwon,Bishwajit Saha,Sang-Pil Mun,Kazunori Nishimura,Mutsuo Nakaoka 전력전자학회 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.1
Conventional series-resonant pulse frequency modulation controlled DC-DC high power converters with a high-frequency transformer link which is designed for driving the high power microwave generator has the problem of hard switching commutation at turn-on and turn-off of active power switching devices. This problem is due to the influence of the magnetizing current of the high-frequency transformer. This paper presents a novel prototype for a high-frequency transformer using parasitic parameters with a lossless inductive snubber and a series resonant capacitor assisted series-resonant zero current switching pulse frequency modulated DC-DC power converter, which is designed using a high power magnetron for microwave ovens. In order to implement a complete and efficient soft switching commutation, the performance of the new converter topology is practically confirmed and evaluated in the prototype of a power microwave generator.
Mikiya Matsuda,Hisayuki Sugimura,Tarek Ahmed,Eiji Hiraki,Kazunori Nishimura,Hyun Woo Lee,Mutsuo Nakaoka 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
This paper presents a cost effective PDM (Pulse Density Modulation) controlled current source type high frequency edge resonant high frequency inverter using a single power semiconductor switch for driving and dimming the dielectric barrier discharge based rare gas fluorescent lamp. The current source-fed class E edge resonant soft<br/> switching inverter treated here, which is proposed as the circuit duality the voltage source-fed class E edge resonant soft switching inverter using a single switch, are evaluated on the basis of the simulation results and experimental ones and discussed for operating characteristics of the rare gas (Xe) barrier discharge fluorescent lamp from an application point of view.
Kentaro Fujita,Hidekazu Muraoka,Tarek Ahmed,Eiji Hiraki,Mutsuo Nakaoka,Hyun Woo Lee,Kazunori Nishimura 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
This paper presents two types of high frequency resonant inverters using power MOSFETs for driving the next generation rare gas fluorescent lamp based on the dielectric barrier discharge phenomenon for liquid crystal backlight in personal computer and car navigation equipment, which has no harmful influence for environment and human body. The high frequency resonant inverters, which include the royer type parallel resonant class D high frequency inverter using two power switches and class E edge resonant high frequency inverter using a single power switch, one is generally used as a light source driver and the other is newly introduced for the purpose of high efficiency and low cost in total system. The experimental performances are comparatively evaluated from the viewpoints of performance evaluations in these resonant<br/> inverters, are discussed as compared with the royer type and class E type high frequency resonant inverters. Moreover, this paper discusses wide and linear control characteristics on the basis of Pulse Density Modulation (PDM) control scheme for voltage source class E edge-resonant inverter.
Kwon, Soon-Kurl,Saha, Bishwajit,Mun, Sang-Pil,Nishimura, Kazunori,Nakaoka, Mutsuo The Korean Institute of Power Electronics 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.1
Conventional series-resonant pulse frequency modulation controlled DC-DC high power converters with a high-frequency transformer link which is designed for driving the high power microwave generator has the problem of hard switching commutation at turn-on and turn-off of active power switching devices. This problem is due to the influence of the magnetizing current of the high-frequency transformer. This paper presents a novel prototype for a high-frequency transformer using parasitic parameters with a lossless inductive snubber and a series resonant capacitor assisted series-resonant zero current switching pulse frequency modulated DC-DC power converter, which is designed using a high power magnetron for microwave ovens. In order to implement a complete and efficient soft switching commutation, the performance of the new converter topology is practically confirmed and evaluated in the prototype of a power microwave generator.