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MIXING CONDITIONS WITH SPRAY-JET INTERACTION FOR EFFECTIVE SOOT REDUCTION IN DIESEL COMBUSTION
Takemi Chikahisa,Yukio Hishinuma,Hirohisa Ushida 한국자동차공학회 2002 International journal of automotive technology Vol.3 No.1
The authors have reported significant reductions in particulate emissions of diesel engines by generating strong turbulence during the combustion process. This study aims to identify optimum conditions of turbulent mixing for effective soot reduction during combustion. The experiments were conducted with a constant volume combustion vessel equipped with a jet-generating cell, in which a small amount of fuel is injected during the combustion of the main spray. The jet of burned gas from the cell impinges the main flame, causing changes in the mixing of fuel and air. Observation<br/> was made for a variety combinations of distances between spray nozzle and jet orifice at different directions of<br/> impingement. It is shown that compared with the case without jet flame soot decreases when the jet impinges. When the jet is very close to the flame, it penetrates the soot cloud and causes little mixing. There were no apparent differences in the combustion duration when the direction of impingement was varied, although the mechanisms of soot reduction seemed different. An analysis of local turbulent flows with PIV (Particle Image Velocimetry) showed the relationship between the scale of the turbulence and the size of the soot cloud.<br/>
An AFM-based Edge Profile Measuring Instrument for Diamond Cutting Tools
Takemi Asai,Takenori Motoki,Wei Gao,Bing-Feng Ju,Satoshi kiyono 한국정밀공학회 2007 International Journal of Precision Engineering and Vol.8 No.2
This paper describes an atomic force microscope (AFM)-based instrument for measuring the nanoscale cutting edge profiles of diamond cutting tools. The instrument consists of a combined AFM unit and an optical sensor to align the AFM lip with the top of the diamond cut ling tool edge over a submicron range. In the optical sensor, a laser beam is emitted from a laser diode along the Y-axis and focused to a small beam spot with a diameter of approximately 10 ㎛ at the beam waist. which is then received by a photodiode. The top of the tool edge is first brought into the center of the beam waist by adjusting it in the X-Z-plane while monitoring the variation in the photodiode output. The cutting tool is then withdrawn and its top edge position at the beam center is recorded. The AFM tip can also be positioned at the beam center in a similar manner to align it with the top of the cutting edge. To reduce electronic noise interference on the photodiode output and thereby enhance the alignment accuracy, a technique is applied that can modulate the photodiode output to an AC signal by driving the laser diode with a sinusoidal current. Alignment experiments and edge profile measurements of a diamond cutting tool were carried out to verify the performance of the proposed system.
Comparison of sweetness preference and motivational factors between Korean and Japanese children
Takemi, Yukari,Woo, Taejung 한국영양학회 2017 Journal of Nutrition and Health Vol.50 No.1
Purpose: This study was performed to examine motivational factors affecting sweetness preference in Korean and Japanese children. We identified meaningful variables that could be targeted to nutrition education interventions designed to overcome innate barriers and reduce sweetness preference and sweet food intake in Korean and Japanese children. Methods: Questionnaire surveys and sweetness preference test were conducted to examine variables affecting behavioral intention (BI) regarding sweetness preference. Questionnaire variables were based on the theory of planned behavior. Participants were recruited from one urban school from each country. In total, 166 children (mean age: 8.4 years) and their guardians (n = 166) participated in the study. A trained research assistant provided all children with personal guidance regarding completion of the sweetness preference test and survey questionnaire at school. The data were analyzed using Pearson"s correlation coefficients, t tests, repeated measure ANOVA, and stepwise multiple regression analysis (significance level: p < 0.05). Results: Perceived behavioral control (PBC) and parenting practice were significantly associated with BI in both groups. Motivation to comply affected BI only in Japanese children, whereas affective attitude was associated with BI only in Korean children. In predicting sweetness preference, BI was associated only in Japanese children, whereas sweets consumption frequency had a significant effect in Korean children. Conclusion: The study shows similarities and differences in motivational factors, which could be considered when developing nutrition education programs in Korea and Japan. PBC and parenting practice were common factors in predicting BI. In predicting sweetness preference, BI had a significant effect on Japanese children, whereas sweets consumption frequency was the greatest contributor in Korean children.