์ž…๋ ฅ์ง€์  a/d 0.4 ๋‚˜๋จธ์ง€ ๋‹ค 1๋กœ ํ•˜๋‹ˆ ์ฑ„ํ„ฐ๋ง ์žˆ์—ˆ๋Š”๋ฐ 1๋ง๊ณ  1.8๋กœ ํ•˜๋‹ˆ๊นŒ ๊ณ ์ณ์ง