• Phonetics and Speech Sciences
• /
• v.2 no.4
• /
• pp.51-58
• /
• 2010

English vowels play an important role in the daily communication between Korean students and international visitors. However, many Korean students still have difficulty producing them distinctively. Vowels vary according to shapes of oral and pharyngeal cavities, which are mainly determined by the degree of jaw opening and tongue position. Yang (2008a) proposed a simplified chart of English and Korean vowels for an educational purpose. He also suggested to use wooden chopsticks to secure distinguishable jaw openings. The purpose of this study is to tap whether wooden chopsticks can be applicable to a method for correcting English vowel pronunciation. Twelve male and female students participated in the recordings of eight /hVd/ words followed by additional recordings with wooden chopsticks between upper and lower teeth. The first and second formant trajectories of both natural and controlled vowel productions were obtained and compared at six equidistant measurement points using Praat. Results showed that the formant values of natural vowel productions were comparable to those of controlled productions. Vowels with similar formant trajectories of male students were separated with the aid of chopsticks. The width of each chopstick could be controlled similarly in the experiment. The author concludes that wooden chopsticks can be useful to correct vowel pronunciation. Further studies are desirable for native speakers to make perceptual evaluations of controlled vowel productions by nonnative speakers.

• Journal of Food Hygiene and Safety
• /
• v.23 no.3
• /
• pp.218-221
• /
• 2008

The levels of sulfites in wooden chopsticks were analyzed using two different methods, distillation-alkali titration and ion chromatography. According to the two methods, Sulfur dioxide($SO_2$) was validated by 0.6 and 0.2 ${\mu}ml$ of limit of detection(LOD), 1.8 and 0.5 ${\mu}ml$ of limit of quantification, (LOQ) and a $R^2>0.998$ for linearity, respectively. The recoveries of $SO_2$ from food simulants spiked ar levels of 100 ppm were 70.2-100.2%. 158 samples of wooden chopsticks were monitored the migrated amounts of sulfites. Sulfites were detected in 30 samples in ranged of 0.6 to 15.5 ppm. Maximum migration level, 15.5 ppm of sulfites was considered giving no harmful effect to human since it was reached 5.5% of estimated SML.

• Communications of Mathematical Education
• /
• v.36 no.4
• /
• pp.627-644
• /
• 2022

In this study various angle trisection tools based on Archimedes' insertion method were investigated, some tools were fabricated and their characteristics were compared. Through these works, it was found that factors such as the convenience of use, arbitrariness of the trisected angle, and simplicity of structure should be considered in the production and utilization of the trisection tool. Considering the factors described above, attention was paid to the method proposed by Veprtskii A.I. in 1888 as a making method of the angle trisection tool. In this study, we improved the method proposed by Veprtskii A.I., we used two wooden chopsticks and a string to make an angle trisection tool. The improved trisection tool had fewer parts than other trisection tools, a simple structure, and more convenient usage. In particular, this tool divided an arbitrary angle(not a specific angle) into the same three parts, and the production cost was low and the production process was simple. This tool is expected to be widely used in concrete activities related to the properties of the exterior angles of triangles and the properties of isosceles triangles in mathematics classrooms.