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岡田明(Akira Okada) 한국세라믹학회 2006 세라미스트 Vol.9 No.6
The status of structural ceramics in Japan is presented. Use of ceramics for structural components had been limited due to their brittleness, and the successful application was wear resistant parts such as thread guides and ceramic cutting tools up to around 1980. Sinιc then, considerable work has been done for applying ceramics to mechanical parts, and automotive components made of silicon nitride were developed and commercialized in 1980s. Unfortunately, the application of silicon nitride to automotive engines is not so popular in these days. Instead, a Variety of structural ceramics such as alunrina, silicon carbide and zirconia have recently extended the market, and the expanded application includes vacuum process p따ts for manufacturing senriconductor and liquid crystal devices, refractory tubes for casting aluminum alloy, and dies for optical lens fornring. In addition, cordierite honeycombs and diesel particulate filters are widely used in automobiles. In the present review, the recent application of structural ceramics to automobiles and industries in Japan is summarized.
Accurate Determination of Childhood Food Allergy Prevalence and Correction of Unnecessary Avoidance
Yuki Okada,Takumi Yamashita,Hideki Kumagai,Yoshihiko Morikawa,Akira Akasawa 대한천식알레르기학회 2017 Allergy, Asthma & Immunology Research Vol.9 No.4
Purpose: Because the true prevalence of food allergy (FA), as based on the results of an oral food challenge test (OFC), is unknown, it is likely that children with suspected FA unnecessarily eliminate potentially causative foods. This study aimed to identify the prevalence of FA and to determine the proportion of children who unnecessarily eliminate food. Methods: To identify children with FA, a primary survey was conducted via a questionnaire with all children aged 0-18 years in Niijima village (remote islands of Japan). In the secondary survey, a detailed medical interview was conducted by doctors with children who currently did not eat some foods. The third survey involved serum food-specific immunoglobulin E (IgE) tests and an OFC for children with suspected FA. Results: Of 376 enrolled children, 374 (99.5%) completed the questionnaire. Some foods were eliminated by 18.6% and 13.0% of all children and those ≥6 years old, respectively. The target population for the secondary survey included 69 children who all completed the medical interview. The target population for the third survey consisted of 35 children, of whom 26 (74.3%) underwent the blood test. An OFC was performed 35 times with 20 children. As a result, the prevalence of FA was 4.9% in children of all ages and 4.7% in those ≥6 years old. Moreover, 55.0% children were able to cease eliminating food intake. Conclusions: It is possible that a considerable number of children unnecessarily eliminate food because of suspected FA.
A Perspective of Reconfigurable RF Circuits
Kenichi Okada,Akira Matsuzawa 에스케이텔레콤 (주) 2010 Telecommunications Review Vol.20 No.5
Electronic devices have become mature and been diversified, and flexibility is becoming increasingly important in integrated circuits. Circuits have obtained flexibility and reconfigurability at various levels due to digitization, i.e. simplification, but real-world interfaces such as external communications and sensors intrinsically require analog circuits rather than digital. Digital signals can be processed by PCs, DSPs, FPGAs, custom LSIs, and other digital circuits. In analog circuits, however, general-purpose products offer only a limited and fixed range of functions. The development of reconfigurable analog RF circuits will provide a means of breaking through this impasse and realize both flexibility and high performance. Here we provide a forward-looking perspective on reconfigurable analog RF circuit technology; in particular it s present and future key components, and describes the pathway for innovation and change.
Effect of Arrangement of Design Elements on Recognition of Complex Signs
Maki Ishihara,Akira Okada,Kuniko Yamashita 대한인간공학회 2007 大韓人間工學會誌 Vol.26 No.4
Due to the expansion of cities and the increasing number of large-scale and complex public spaces, there is an increase in public signage. Moreover, the information described on these signs tends to be diverse and complicated. Complex signs that contain multiple destinations or other information must be considered to determine not only the proper size, color, etc. but also the most effective arrangement of design elements. In the previous research, the cognitive utility of complex public signs was estimated using computer simulation software. In the current research, we focused on the objective estimation of the effectiveness of the results obtained in the previous research utilizing an eye mark recording system. Two cognitive engineering experiments clarified five points for improvement in the usability of complex signs, as follows: 1) Parallel construction of characters and pictograms is more efficient. 2) Grouping elements result in rapid recognition of information chunks. 3) Visual characters and pictograms are effective, along with proper density of information. 4) Specific arrangement of sign arrows is effective. 5) Figures on signs influence the sequence of information searches.
Effect of arrangement of design elements on recognition of complex signs
Maki Ishihara,Akira Okada,Kuniko Yamashita 대한인간공학회 2007 대한인간공학회 학술대회논문집 Vol.- No.-
Due to the expansion of cities and the increasing number of large-scale and complex public spaces, there is an increase in public signage. Moreover, the information described on these signs tends to be diverse and complicated. Complex signs that contain multiple destinations or other information must be considered to determine not only the proper size, color, etc. but also the most effective arrangement of design elements. In the previous research, the cognitive utility of complex public signs was estimated using computer simulation software. In the current research, we focused on the objective estimation of the effectiveness of the results obtained in the previous research utilizing an eye mark recording system. Two cognitive engineering experiments clarified five points for improvement in the usability of complex signs, as follows: 1) Parallel construction of characters and pictograms is more efficient. 2) Grouping elements result in rapid recognition of information chunks. 3) Visual characters and pictograms are effective, along with proper density of information. 4) Specific arrangement of sign arrows is effective. 5) Figures on signs influence the sequence of information searches.
Hiromi Isobe,Keisuke Hara,Akira Kyusojin,Manabu Okada,Hideo Yoshihara 한국정밀공학회 2007 International Journal of Precision Engineering and Vol.8 No.2
This paper describes ultrasonically assisted grinding used to obtain a glossy surface quickly and precisely. High-quality surfaces are required for plastic injection molding dies used in the production of plastic parts such as dials for cellular phones. Traditionally, in order to finish the dies, manual polishing by a skilled worker has been required after the machining processes, such as electro discharge machining (EDM), which leaves an affected layer, and milling, which leaves tooling marks. However, manual polishing causes detrimental geometrical deviations of the die and consumes several days to finish a die surface. Therefore, a machining process for finishing dies without manual polishing to improve the surface roughness and form accuracy would be extremely valuable. In this study, a 3D positioning machine equipped with an ultrasonic spindle was used to conduct grinding experiments. An electroplated diamond tool was used for these experiments. Generally, diamond tools cannot grind steel because of excessive wear as a result of carbon atoms diffusing into bulk steel and chips. However, ultrasonically assisted grinding can achieve a fine surface (roughness Rz of 0.4 ㎛) on die steel without severe tool wear. The final aim of this study is to realize mirror surface grinding for injection molding dies without manual polishing. To do this, it is necessary to fabricate an electroplated diamond tool with high form accuracy and low run-out. This paper describes a tool-making method for high precision grinding and the grinding performance of a self-electroplated tool. The ground surface textures, tool performance and tool life were investigated. A ground surface roughness Rz of 0.14 ㎛ was achieved. Our results show that the spindle speed, feed rate and cross feed affected the surface texture. One tool could finish 5000㎟ of die steel surface without any deterioration of the ground surface roughness.
New Error Correcting Scheme for Hard Detected QAM Signal
Yamaoka, Tomaya,Yamazato, Takaya,Okada, Hiraku,Katayama, Masaaki,Ogawa, Akira 통신위성우주산업연구회 2004 Joint Conference on Satellite Communications Vol.2004 No.-
In order to achieve high speed satellite communication, we propose a new R=m-2/m error correcting scheme for hard detected $2^m$-QAM signal, where we consider m $\geq$ 6. The main focus of the paper is to improve the performance even in the case of hard-detection. As results, we found that our proposed error=correcting scheme achieves good error performance despite the hard detection and the high coding rate.