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INTERIORS AND CLOSURES IN A SET WITH AN OPERATION
Nakaoka, Fumie,Oda, Nobuyuki Korean Mathematical Society 2014 대한수학회논문집 Vol.29 No.4
A set with an operation defined on a family of subsets is studied. The operation is used to generalize the topological space itself. The operation defines the operation-open subsets in the set. Relations are studied among two types of the interiors and the closures of subsets. Some properties of maximal operation-open sets are obtained. Semi-open sets and pre-open sets are defined in the sets with operations and some relations among them are proved.
Nakaoka, Yoshikazu,Nishida, Keigo,Narimatsu, Masahiro,Kamiya, Atsunori,Minami, Takashi,Sawa, Hirofumi,Okawa, Katsuya,Fujio, Yasushi,Koyama, Tatsuya,Maeda, Makiko,Sone, Manami,Yamasaki, Satoru,Arai, Yu American Society for Clinical Investigation 2007 The Journal of clinical investigation Vol.117 No.7
Study on Forward Collision Warning System Adapted to Driver Characteristics and Road Environment
Masumi Nakaoka,Pongsathorn Raksincharoensak,Masao Nagai 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
Forward collision warning systems target a major crash type: rear-end crashes with a moving or parked vehicle which covers 30% of all accidents in Japan. The development of this system contributes to the reduction of road accidents. Many collision warning algorithms have recently been proposed and developed in automobile markets but they are based on Pre-Crash Safety system concept which activates in critical driving situation. In future, the collision warning device should be designed to be activated earlier than the current pre-crash safety system in order to induce driver’s own braking maneuver to prevent collision as well as near-miss incident. This paper focuses on a forward collision warning algorithm based on road friction coefficient and driver characteristics. The effectiveness of the algorithm is verified by using driving simulator experiments and experimental car in urban area.
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.
Hiraki, Eiji,Nakaoka, Mutsuo The Korean Institute of Power Electronics 2003 JOURNAL OF POWER ELECTRONICS Vol.3 No.1
This paper presents a performance analysis of typical Auxiliary Resonant Commutation Snubber-assisted three phase voltage source soft switching inverter which can operate under a condition of Zero Voltage Switching (ZVS) using a digital control scheme which is suitable for high power applications compared with resonant DC link snubber assisted soft switching inverter. The system performances of this inverter are illustrated and evaluated on the basis of experimental results.
Rukonuzzaman, M.,Nakaoka, Mutsuo The Korean Institute of Power Electronics 2002 JOURNAL OF POWER ELECTRONICS Vol.2 No.1
An advanced active power filter for the compensation of instantaneous harmonic current components in nonlinear current load is presented in this paper. A novel signal processing technique using an adaptive neural network algorithm is applied for the detection of harmonic components generated by three-phase nonlinear current loads and this method can efficiently determine the instantaneous harmonic components in real time. The control strategy of the switching signals to compensate current harmonics of the three-phase inverter is also discussed and its switching signals are generated with the space voltage vector modulation scheme. The validity of this active filtering processing system to compensate current harmonics is substantiated on the basis of simulation results.
Hiraki, Eiji,Nakaoka, Mutsuo The Korean Institute of Electrical Engineers 2002 KIEE International Transactions on Electrical Mach Vol.b2 No.3
In this paper, a prototype of an active auxiliary quasi-resonant DC link (QRDCL) snubber assisted voltage source bidirectional power converter (AC to DC and DC to AC) operating at zero voltage soft-switching (BVS) PWM nlode is presented for a Battery Energy Storage System (BESS). The operating principle of this QRDCL circuit and multifunctional control-based converter system, including PWM inverter mode in which energy flows from the battery bank to the three-phase utility-grid in addition to an active PWM converter mode in which energy flows from the utility-grid to the battery banks are described respectively by the control implementation on the basis of d-q coordinate plane transformation. The multifunctional operation characteristics of this three-phase ZVS PWM bi-directional converter with QRDCL is demonstrated fer a BESS under the power conditioning and processing schemes of energy supply mode and energy storage mode, and compared with a conventional three-phase hard switching PWM bi-directional converter for a BESS. The effectiveness of the three-phase ZVS PWM hi-directional converter with QRDCL is proven via the simulation analysis.
Hirachi, Katsuya,Nakaoka, Mutsuo The Korean Institute of Power Electronics 2003 JOURNAL OF POWER ELECTRONICS Vol.3 No.4
The rapid expansion of small computers over the last 10-odd years has brought about great changes in the circumstances affecting UPSs. There are strong demands that UPSs become much smaller and lighter, and more economical, which has resulted in the wide application of the circuit topology without transformer. A disadvantage of such UPS topology is that the DC link voltage is very high, which invites decreased reliability and increased cost of battery bank. Some circuit configurations were proposed to eliminate this disadvantage, but they still had problems. In this paper, a novel circuit configuration which eliminates these problems is proposed and evaluated by the experimental results of prototype UPS.
Voltage Source Resonant Inverter for Excimer Gas Discharge Load
Koudriavtsev, Oleg,Nakaoka, Mutsuo The Korean Institute of Power Electronics 2002 JOURNAL OF POWER ELECTRONICS Vol.2 No.3
Silent gas discharge method has been widely applied fur ozone production, ultraviolet light and UV laser generation. Since ozone and ultraviolet applications have tendency to spread widely in industry, the development of efficient and low - cost power supply for such systems is an important task at present. This paper introduces high-frequency inverter type mode power supply designed fur ozone generation tube and ultraviolet generation excimer lamp and considerations on the design of the inverter and pulse density modulation control strategy applied in it.
Hiraki Eiji,Nakaoka Mutsuo,Sugimoto Shigeyuki,Ogawa Shigeaki The Korean Institute of Power Electronics 2005 JOURNAL OF POWER ELECTRONICS Vol.5 No.1
This paper presents a novel prototype of an active auxiliary quasi-resonant snubber(Auxiliary Quasi-Resonant Commutation Block-Link; ARCB)-assisted three phase voltage source soft switching space voltage vector modulated PFC rectifier, which uses Zero Voltage Soft Switching (ZVS) commutation. The operating principles of this digitally-controlled three phase soft switching PWM-PFC rectifier system with an instantaneous power feedback scheme are illustrated and its steady-state performance is evaluated using computer-aided simulation analysis.