Mobile QR Code QR CODE : Journal of the Korean Society of Civil Engineers

  1. ์ „๋‚จ๋Œ€ํ•™๊ต ๊ณต๊ณผ๋Œ€ํ•™ ํ† ๋ชฉ๊ณตํ•™๊ณผ ๊ต์ˆ˜ (Chonnam National University)
  2. ์ „๋‚จ๋Œ€ํ•™๊ต ๊ณตํ•™๋Œ€ํ•™ ํ•ด์–‘ํ† ๋ชฉ๊ณตํ•™๊ณผ ํ•™์ˆ ์—ฐ๊ตฌ๊ต์ˆ˜ (Chonnam National University)


์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ, ์ˆ˜๋ฆฌ์‹คํ—˜, ํˆฌ๊ณผํ˜•, ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜, ๊ฒฝํ—˜์‹
Submerged structure, Laboratory experiment, Permeable type, Wave transmission coefficient, Empirical formula

  • 1. ์„œ ๋ก 

  • 2. ๊ธฐ์กด ์ž๋ฃŒ ๋ถ„์„

  •   2.1 ๊ธฐ์กด ์„ค๊ณ„์‚ฌ๋ก€

  •   2.2 ๊ธฐ์กด ์—ฐ๊ตฌ๊ฒฐ๊ณผ

  • 3. ์‹คํ—˜์‹œ์„ค ๋ฐ ์‹คํ—˜์กฐ๊ฑด

  •   3.1 ์‹คํ—˜์‹œ์„ค

  •   3.2 ์‹คํ—˜์กฐ๊ฑด

  • 4. ์‹คํ—˜๊ฒฐ๊ณผ ๋ถ„์„

  •   4.1 ์ƒ๋Œ€ํŒŒ๊ณ  ๊ณ„์ธก๊ฒฐ๊ณผ ๋ฐ ์ „๋‹ฌํŒŒ๊ณ  ์‚ฐ์ •๋ฐฉ๋ฒ•

  •   4.2 D n =0.042 m ์กฐ๊ฑด์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •

  •   4.3 D n =0.074 m ์กฐ๊ฑด์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •

  •   4.4 ํˆฌ๊ณผํ˜• ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •

  • 5. ๊ฒฐ ๋ก 

1. ์„œ ๋ก 

์šฐ๋ฆฌ๋‚˜๋ผ ์—ฐ์•ˆ์˜ ์นจ์‹์ •๋„๋Š” ์šฐ๋ คํ• ๋งŒํ•œ ์ˆ˜์ค€์— ์ด๋ฅด๋ €์œผ๋ฉฐ, ์ด๋Ÿฌํ•œ ์นจ์‹์€ ๋‹ค์–‘ํ•œ ์—ฐ์•ˆ๊ฐœ๋ฐœ(๋งค๋ฆฝ์‚ฌ์—…๊ณผ ํ•ญ๋งŒ๊ฐœ๋ฐœ ๋“ฑ), ํ† ์‚ฌ์œ ์ž…์„ ์ €ํ•ดํ•˜๋Š” ์œ ๋กœ๋ณ€๊ฒฝ ๋ฐ ๋Œ๊ณผ ํ•˜๊ตฌ๋‘‘ ๋“ฑ์˜ ๊ฑด์„ค, ๊ธฐํ›„๋ณ€ํ™”์— ๋”ฐ๋ฅธ ํ•ด์ˆ˜๋ฉด ์ƒ์Šน, ํƒœํ’ ๋ฐ ๋„ˆ์šธ ๋“ฑ๊ณผ ๊ฐ™์€ ๊ณ ํŒŒ๋ž‘์˜ ๋นˆ๋ฒˆํ•œ ๋‚ด์Šต ๋“ฑ์ด ์ฃผ๋œ ์›์ธ์œผ๋กœ ๋ถ„์„๋˜๊ณ  ์žˆ๋‹ค. ์ด๋Ÿฌํ•œ ์—ฐ์•ˆ์นจ์‹์„ ์ €๊ฐ์‹œํ‚ค๊ธฐ ์œ„ํ•œ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ตญ๋‚ด์—์„œ๋Š” ๋Œ€๋ถ€๋ถ„ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ(submerged structure)์˜ ์„ค์น˜๋ฅผ ์ ์šฉํ•˜๊ณ  ์žˆ๋‹ค. ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์€ ๋‚ด์ŠตํŒŒ์˜ ํŒŒ๋ž‘์„ ์ƒ๋‹จ์—์„œ ์‡„ํŒŒ์‹œ์ผœ ํŒŒ๋ž‘์—๋„ˆ์ง€๋ฅผ ๊ฐ์†Œ์‹œํ‚ค๋Š” ๊ธฐ๋Šฅ์„ ํ•˜๋ฉฐ, ์ด๋Ÿฌํ•œ ํŒŒ๋ž‘ ๊ฐ์‡ ํšจ๊ณผ๋ฅผ ์œ„ํ•ด์„œ๋Š” ๋น„๊ต์  ๋„“์€ ํญ์˜ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์ด ์š”๊ตฌ๋œ๋‹ค. ๋Œ€ํ‘œ์ ์ธ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์€ ์ž ์ œ์™€ ์ธ๊ณต๋ฆฌํ”„(artificial reef)๋ฅผ ๋“ค ์ˆ˜ ์žˆ๋‹ค.

๊ตญ๋‚ด์— ์ ์šฉ๋œ 17๊ฐœ์†Œ 34๊ฐœ ๋‹จ๋ฉด์„ ๊ฒ€ํ† ํ•ด๋ณธ ๊ฒฐ๊ณผ, ์ ์šฉ๋œ ํ”ผ๋ณต์žฌ๋Š” Tetrapod์ด๊ณ , ์„ค์น˜์ˆ˜์‹ฌ์ด ๋น„๊ต์  ๋‚ฎ๊ธฐ ๋•Œ๋ฌธ์— ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์ œ์ฒด๋ฅผ Tetrapod๋งŒ์œผ๋กœ ๊ตฌ์„ฑํ•œ ํˆฌ๊ณผํ˜• ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์ด ๋Œ€๋ถ€๋ถ„์ด๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ํ”ผ๋ณต์žฌ๋กœ Tripod ๋˜๋Š” ํ”ผ๋ณต์„์„ ์‚ฌ์šฉํ•˜์—ฌ ๊ฒฝ์‚ฌํ˜• ๋ฐ ๋ถˆํˆฌ๊ณผํ˜•์˜ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์„ ์ ์šฉํ•œ ์ผ๋ถ€ ์‚ฌ๋ก€๋„ ์กฐ์‚ฌ๋˜์—ˆ๋‹ค.

์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ๊ธฐํ•˜ํ•™์  ์ œ์›์€ ๋ชฉํ‘œ๋กœ ํ•˜๋Š” ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ์–ป์„ ์ˆ˜ ์žˆ๋Š” ์กฐ๊ฑด์œผ๋กœ ์„ค์ •๋˜๋Š” ๊ฒƒ์ด ์ผ๋ฐ˜์ ์ด๋‹ค. ๋”ฐ๋ผ์„œ ์ˆ˜๋ฆฌ๋ชจํ˜•์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜์ง€ ์•Š๋Š” ๊ฒฝ์šฐ์—๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ๊ตฌ์กฐํ˜•์‹๋ณ„๋กœ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ์‚ฐ์ •ํ•  ์ˆ˜ ์žˆ๋Š” ๊ฒฝํ—˜์‹์ด ์š”๊ตฌ๋œ๋‹ค. ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ๋˜๋Š” ์ € ๋งˆ๋ฃจ๋†’์ด ๊ตฌ์กฐ๋ฌผ(low-crested structure)์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๋Š” ์œ ๋Ÿฝ๊ณผ ์ผ๋ณธ์„ ์ค‘์‹ฌ์œผ๋กœ ์ˆ˜ํ–‰๋˜์—ˆ๋‹ค. ์œ ๋Ÿฝ์˜ ๊ฒฝ์šฐ์—๋Š” ์ฃผ ํ”ผ๋ณต์žฌ ํ•˜๋ถ€์— ์ œ์ฒด์‚ฌ์„์„ ์„ค์น˜ํ•œ ๊ฒฝ์‚ฌํ˜• ์ € ๋งˆ๋ฃจ๋†’์ด ๊ตฌ์กฐ๋ฌผ์— ๋Œ€ํ•œ ์—ฐ๊ตฌ(Allsop, 1983; Powell and Allsop, 1985; van der Meer and dโ€™Angremond, 1991; van der Meer and Daemen, 1994; dโ€™Angremond et al., 1996; Kramer et al., 2005, van der Meer et al., 2005), ์ผ๋ณธ์—์„œ๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์— ๋Œ€ํ•œ ์—ฐ๊ตฌ(Takayama et al., 1985; Uda, 1988)๊ฐ€ ๋Œ€๋ถ€๋ถ„์ด๋‹ค. ๊ตญ๋‚ด ์—ฐ๊ตฌ๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์— ์˜ํ•œ ํŒŒ๋ž‘๋ณ€ํ˜•์— ๋Œ€ํ•œ ์ˆ˜์น˜ํ•ด์„์ด ๋Œ€๋ถ€๋ถ„์ด๋ฉฐ, ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์— ์˜ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์— ๋Œ€ํ•œ ์‹คํ—˜์  ์—ฐ๊ตฌ๋Š” ๋ฏธ๋ฏธํ•œ ์‹ค์ •์ด๋‹ค. Ryu et al.(2015)์€ ๊ตญ๋‚ด ์ธ๊ณต๋ฆฌํ”„ ์„ค๊ณ„์‚ฌ๋ก€ ๋ถ„์„ ๋“ฑ์„ ํ†ตํ•ด ์„ค๊ณ„ ๊ฐœ์„ ์‚ฌํ•ญ์„ ์ œ์•ˆํ•˜์˜€๋‹ค.

๊ตญ๋‚ด์—์„œ ์ผ๋ฐ˜์ ์œผ๋กœ ์ ์šฉํ•˜๊ณ  ์žˆ๋Š” ํˆฌ๊ณผํ˜• ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์— ๋Œ€ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์€ Takayama et al.(1985)์˜ ์—ฐ๊ตฌ๊ฐ€ ๋Œ€ํ‘œ์ ์ด๋ฉฐ, ๊ตญ๋‚ด ํ•ญ๋งŒ ๋ฐ ์–ดํ•ญ์„ค๊ณ„๊ธฐ์ค€(MOF, 2014)์—๋„ Takayama et al.(1985)์˜ ์—ฐ๊ตฌ์„ฑ๊ณผ๊ฐ€ ์ˆ˜๋ก๋˜์–ด ์žˆ๋‹ค. Takayama et al.(1985)์˜ ์—ฐ๊ตฌ์„ฑ๊ณผ๋Š” ์„ค๊ณ„ํŒŒ๋ž‘ ์กฐ๊ฑด์„ ๋Œ€์ƒ์œผ๋กœ ํ•œ ํˆฌ๊ณผํ˜• ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์— ์žˆ์–ด์„œ๋Š” ์ ์šฉ์„ฑ์ด ์ถฉ๋ถ„ํ•˜์ง€๋งŒ, ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ƒ๋Œ€์ƒ๋‹จํญ(=์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ƒ๋‹จํญ/์ž…์‚ฌํŒŒ์˜ ํŒŒ์žฅ)์ด 0.7๋ณด๋‹ค ํฌ๊ฒŒ ๋˜๋ฉด ์Œ(-)์˜ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ์‚ฐ์ •๋˜๋Š” ๋ฌธ์ œ์ ์ด ์žˆ๋‹ค. ๋˜ํ•œ ๊ธฐ์กด ์—ฐ๊ตฌ์„ฑ๊ณผ์˜ ๋Œ€๋ถ€๋ถ„์ด ์ƒ๋Œ€์ƒ๋‹จํญ์ด ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ์ง€์ˆ˜์ ์ธ ๊ฐ์†Œ๋ฅผ ๋ณด์ด๋Š”๋ฐ ๋ฐ˜ํ•ด, Takayama et al.(1985)์˜ ์‚ฐ์ •์‹์€ ์„ ํ˜•์ ์ธ ๊ฐ์†Œ๋ฅผ ๋ณด์ธ๋‹ค.

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ํˆฌ๊ณผํ˜• ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์„ ๋Œ€์ƒ์œผ๋กœ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์„ ์œ„ํ•œ 2์ฐจ์› ์ˆ˜๋ฆฌ์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜์—ฌ Takayama et al.(1985)์˜ ์—ฐ๊ตฌ์„ฑ๊ณผ๋ฅผ ๋Œ€์ฒดํ•  ์ˆ˜ ์žˆ๋Š” ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์‹์„ ์ œ์•ˆํ•˜๋Š” ๊ฒƒ์ด ์ฃผ๋œ ๋ชฉํ‘œ์ด๋‹ค. ์ด๋ฅผ ์œ„ํ•ด ์ž…์‚ฌํŒŒ(์œ ์˜ํŒŒ๊ณ  ๋ฐ ์œ ์˜์ฃผ๊ธฐ) ์ œ์›, ์ œ์ฒด์„ค์น˜์ˆ˜์‹ฌ, ์ƒ๋‹จ์—ฌ์œ ๊ณ , ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ํญ, ํ”ผ๋ณต์žฌ์˜ ๊ทœ๊ฒฉ, ํ”ผ๋ณต์žฌ์˜ ์„ค์น˜ ์ธต์ˆ˜ ๋“ฑ์„ ๋ณ€ํ™”์‹œํ‚ค๋ฉฐ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์— ์˜ํ•œ ์ „๋‹ฌํŒŒ๊ณ  ๊ณ„์ธก ์ˆ˜๋ฆฌ์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ์‹คํ—˜์กฐ๊ฑด๋ณ„๋กœ ๊ณ„์ธก๋œ ์ „๋‹ฌํŒŒ๊ณ  ์ž๋ฃŒ๋กœ๋ถ€ํ„ฐ ์—ฌ๋Ÿฌ ๊ฐ€์ง€ ๋ฌด์ฐจ์›๋ณ€์ˆ˜๋ฅผ ์ด์šฉํ•˜์—ฌ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์‹์„ ์ œ์•ˆํ•˜๊ณ , ๊ธฐ์กด ์—ฐ๊ตฌ์„ฑ๊ณผ์™€ ๋น„๊ตํ•˜์˜€๋‹ค.

2. ๊ธฐ์กด ์ž๋ฃŒ ๋ถ„์„

2.1 ๊ธฐ์กด ์„ค๊ณ„์‚ฌ๋ก€

์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์„ ์œ„ํ•œ ์‹คํ—˜์กฐ๊ฑด์€ ๊ธฐ์กด ์„ค๊ณ„ ๋‹จ๋ฉด์„ ๋ถ„์„ํ•˜์—ฌ ์„ค์ •ํ•˜์˜€๋‹ค. ๊ตญ๋‚ด์˜ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์ด ์„ค์น˜๋œ 17๊ฐœ์†Œ์˜ 34๊ฐœ ๋‹จ๋ฉด์„ ๋ถ„์„ํ•˜์˜€์œผ๋ฉฐ, ํ”ผ๋ณต์žฌ๋กœ๋Š” ๋Œ€๋ถ€๋ถ„ Tetrapod๊ฐ€ ์ ์šฉ๋œ ์‚ฌ๋ก€์ด๋‹ค.

Fig. 1์€ 34๊ฐœ ๋‹จ๋ฉด์„ ๋ถ„์„ํ•˜์—ฌ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ƒ๋‹จํญ( W ), ์„ค์น˜์ˆ˜์‹ฌ( d ), ์ƒ๋‹จ์—ฌ์œ ๊ณ ( R C ), ์„ค๊ณ„ํŒŒ์˜ ์œ ์˜ํŒŒ๊ณ ( H S ) ๋ฐ ์œ ์˜์ฃผ๊ธฐ( T S ) ํ•ญ๋ชฉ์œผ๋กœ ์ •๋ฆฌํ•˜์—ฌ ๋„์‹œํ•œ ๊ฒƒ์ด๋‹ค. Fig. 1(a)๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ƒ๋‹จํญ( W )์„ ๋„์‹œํ•œ ๊ฒƒ์œผ๋กœ์„œ W =10.8~50 m ๋ฒ”์œ„์ด๋‹ค. ์ „์ฒด 34๊ฐœ ๋‹จ๋ฉด ์ค‘ 19๊ฐœ ๋‹จ๋ฉด(์ „์ฒด์˜ ์•ฝ 56 %)์ด W =40 m, 5๊ฐœ ๋‹จ๋ฉด(์ „์ฒด์˜ ์•ฝ 15 %)์ด W =50 m, 4๊ฐœ ๋‹จ๋ฉด(์ „์ฒด์˜ ์•ฝ 12 %)์ด W = 30 m๋กœ์„œ ๊ตญ๋‚ด์—์„œ ์„ค๊ณ„๋œ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์•ฝ 83 %๊ฐ€ W =30~50 m๋กœ ๋น„๊ต์  ๋„“์€ ์ƒ๋‹จํญ์„ ๊ฐ€์ง„๋‹ค. Fig. 1(b)๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์ด ์„ค์น˜๋œ ์ˆ˜์‹ฌ( d )์œผ๋กœ์„œ d =3~8 m ๋ฒ”์œ„์ด๋ฉฐ, d =3~6 m๊ฐ€ ๋Œ€๋ถ€๋ถ„์„ ์ฐจ์ง€ํ•œ๋‹ค. Fig. 1(c)๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์ƒ๋‹จ์œผ๋กœ๋ถ€ํ„ฐ ์ •์ˆ˜๋ฉด(still water level, SWL)๊นŒ์ง€์˜ ๋†’์ด์ธ ์ƒ๋‹จ์—ฌ์œ ๊ณ ( R C )๋กœ์„œ R C =0.5 m๊ฐ€ ์ „์ฒด์˜ ์•ฝ 59 %์ด๋ฉฐ, R C =0.05 m ๋ฐ 1 m๊ฐ€ ๊ฐ๊ฐ 12 %์ด๋‹ค. Figs. 1(d) and 1(e)๋Š” ๊ฐ๊ฐ ์„ค๊ณ„ํŒŒ์˜ ์œ ์˜ํŒŒ๊ณ ( H S ) ๋ฐ ์œ ์˜์ฃผ๊ธฐ( T S )๋กœ์„œ H S โ‰’4 m ๋‚ด์™ธ, T S โ‰’12 sec ๋‚ด์™ธ๊ฐ€ ๋Œ€๋ถ€๋ถ„์„ ์ฐจ์ง€ํ•œ๋‹ค.

Figure_KSCE_40_05_05_F1.jpg
Fig. 1.

Review of Submerged Structures for the Existing Design Cases

Fig. 2๋Š” Fig. 1์— ์ œ์‹œ๋œ ๊ธฐ์กด ์„ค๊ณ„์‚ฌ๋ก€์˜ ์„ค๊ณ„์กฐ๊ฑด์„ ๋ฌด์ฐจ์›๋ณ€์ˆ˜๋กœ ๋ถ„์„ํ•˜์—ฌ ๋„์‹œํ•œ ๊ฒƒ์ด๋‹ค. ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ƒ๋Œ€์ƒ๋‹จํญ(relative crest width, W / L S )์€ W / L S =0.18~0.68, ์ƒ๋Œ€์—ฌ์œ ๊ณ (relative freeboard, R C / L S )๋Š” R C / L S =0.01~0.36, ํŒŒํ˜•๊ฒฝ์‚ฌ(wave steepness, H S / L S )๋Š” H S / L S =0.02~0.06, ์ƒ๋Œ€์—ฌ์œ ์ˆ˜์‹ฌ(relative crest depth, R C / d )๋Š” R C / d =0.01~0.35์ด๋‹ค(Fig. 2 ์ฐธ์กฐ). ์—ฌ๊ธฐ์„œ, L S ๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์„ค์น˜์ˆ˜์‹ฌ์—์„œ ์œ ์˜์ฃผ๊ธฐ( T S )์— ํ•ด๋‹นํ•˜๋Š” ํŒŒ์žฅ์ด๋‹ค. ์ƒ๋Œ€์—ฌ์œ ๊ณ  R C / H S ๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์ƒ๋‹จ์—์„œ์˜ ์‡„ํŒŒ์ˆ˜์ค€, ํŒŒํ˜•๊ฒฝ์‚ฌ H S / L S ๋Š” ์ž…์‚ฌํŒŒ์˜ ๋น„์„ ํ˜•์„ฑ, ์ƒ๋Œ€์ƒ๋‹จํญ W / L S ๋Š” ์ž…์‚ฌํŒŒ์žฅ ๋Œ€๋น„ ๊ตฌ์กฐ๋ฌผ ํญ์˜ ์˜ํ–ฅ, ์ƒ๋Œ€์—ฌ์œ ์ˆ˜์‹ฌ R C / d ๋Š” ๊ตฌ์กฐ๋ฌผ ์„ค์น˜์œ„์น˜์™€ ๊ตฌ์กฐ๋ฌผ ์ƒ๋‹จ ์ˆ˜์‹ฌ์—์„œ์˜ ์‡„ํŒŒ์ˆ˜์ค€์„ ์ƒ๋Œ€๋น„๊ตํ•˜๋Š” ๋ณ€์ˆ˜์ด๋‹ค.

Figure_KSCE_40_05_05_F2.jpg
Fig. 2.

Dimensionless Parameters of the Existing Design Cases

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” Fig. 2์— ์ œ์‹œ๋œ ๋ฌด์ฐจ์›๋ณ€์ˆ˜ ๋ฒ”์œ„๊ฐ€ ์ตœ๋Œ€ํ•œ ํฌํ•จ๋˜๋„๋ก ์‹คํ—˜์กฐ๊ฑด์„ ์„ค์ •ํ•˜์˜€๋‹ค.

2.2 ๊ธฐ์กด ์—ฐ๊ตฌ๊ฒฐ๊ณผ

ํˆฌ๊ณผํ˜• ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์— ๋Œ€ํ•ด ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜( K T )๋ฅผ ์‚ฐ์ •ํ•  ์ˆ˜ ์žˆ๋Š” ๋Œ€ํ‘œ์ ์ธ ๊ธฐ์กด ์—ฐ๊ตฌ์„ฑ๊ณผ๋Š” Takayama et al.(1985)์˜ ์ œ์•ˆ์‹์ด๋‹ค. Takayama et al.(1985)์€ ์ˆ˜๋ฆฌ์‹คํ—˜ ๊ฒฐ๊ณผ๋ฅผ ์ด์šฉํ•˜์—ฌ ์ƒ๋Œ€์ƒ๋‹จํญ( W / L 0 ), ์ƒ๋Œ€์—ฌ์œ ๊ณ ( R C / H 0 ) ๋ฐ ํŒŒํ˜•๊ฒฝ์‚ฌ( H 0 / L 0 )๋ฅผ ๋ฌด์ฐจ์›๋ณ€์ˆ˜๋กœ ํ•˜์—ฌ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ์‚ฐ์ •ํ•  ์ˆ˜ ์žˆ๋Š” ๊ฒฝํ—˜์‹์„ ์ œ์•ˆํ•˜์˜€์œผ๋ฉฐ, ์ œ์•ˆ์‹์€ Eq. (1)๊ณผ ๊ฐ™์€ ์„ ํ˜•์‹์ด๋‹ค.

$$K_T=-0.92\left(\frac W{L_0}\right)+0.42\left(\frac{R_C}{H_0}\right)+3.80\left(\frac{H_0}{L_0}\right)+0.51$$ (1)

Eq. (1)์—์„œ W ๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ƒ๋‹จํญ, R C ๋Š” ์—ฌ์œ ๊ณ (์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์ƒ๋‹จ์œผ๋กœ๋ถ€ํ„ฐ ์ •์ˆ˜๋ฉด๊นŒ์ง€์˜ ๋†’์ด)์ด๋ฉฐ, H 0 ์™€ L 0 ๋Š” ๊ฐ๊ฐ ์œ ์˜ํŒŒ๊ณ ์™€ ์œ ์˜์ฃผ๊ธฐ์— ํ•ด๋‹นํ•˜๋Š” ํŒŒ์žฅ์œผ๋กœ์„œ ์กฐํŒŒ๊ธฐ ์ „๋ฉด์—์„œ์˜ ๊ณ„์ธก๊ฐ’(์‹ฌํ•ดํŒŒ ์กฐ๊ฑด์— ํ•ด๋‹น)์„ ์ด์šฉํ•˜์˜€๋‹ค. Takayama et al.(1985)์˜ ์‹คํ—˜์€ ํ•ด์ €๊ฒฝ์‚ฌ๊ฐ€ 1:10๊ณผ 1:30์œผ๋กœ ๊ตฌ์„ฑ๋œ ์ˆ˜๋กœ์—์„œ ์ˆ˜ํ–‰๋˜์—ˆ์œผ๋ฉฐ, ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์€ 1:30์˜ ๊ฒฝ์‚ฌ๋ฉด์— ์„ค์น˜๋˜๊ณ , ์‹คํ—˜ํŒŒ๋Š” 1:10์˜ ํ•ด์ €๊ฒฝ์‚ฌ๊ฐ€ ์‹œ์ž‘๋˜๊ธฐ ์ „์˜ ์œ„์น˜์ธ ์กฐํŒŒ๊ธฐ ์ „๋ฉด์—์„œ ์„ค์ •ํ•˜์˜€๋‹ค. Eq. (1)์— ์‚ฌ์šฉ๋˜๋Š” ํŒŒ๋ž‘์ œ์›์ด ํ•ด์ €๊ฒฝ์‚ฌ๊ฐ€ ์‹œ์ž‘๋˜๊ธฐ ์ „์˜ ์ œ์›์ด๊ธฐ ๋•Œ๋ฌธ์— ํ•ด์ €๊ฒฝ์‚ฌ๊ฐ€ ์‹คํ—˜์กฐ๊ฑด๊ณผ ๋‹ค๋ฅผ ๊ฒฝ์šฐ์—๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์„ค์น˜์œ„์น˜์—์„œ์˜ ํŒŒ๋ž‘์ด ๋‹ฌ๋ผ์ ธ Eq. (1)์˜ ์ ์šฉ์— ์ œํ•œ์ ์ด ๋ฐœ์ƒํ•˜๊ฒŒ ๋œ๋‹ค. ๋”ฐ๋ผ์„œ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์„ค์น˜์œ„์น˜์—์„œ์˜ ํŒŒ๋ž‘์ œ์›์„ ์ด์šฉํ•œ ์ œ์•ˆ์‹์˜ ๋„์ถœ์ด ์š”๊ตฌ๋œ๋‹ค.

Eq. (1)์„ ์ด์šฉํ•˜์—ฌ ์ƒ๋Œ€์—ฌ์œ ๊ณ  R C / H 0 =0.1 ์กฐ๊ฑด์—์„œ ์ƒ๋Œ€์ƒ๋‹จํญ( W / L 0 )๊ณผ ํŒŒํ˜•๊ฒฝ์‚ฌ( H 0 / L 0 )๋ฅผ ๋ณ€ํ™”์‹œํ‚ค๋ฉฐ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ์‚ฐ์ •ํ•œ ๊ฒฐ๊ณผ๊ฐ€ Fig. 3์ด๋‹ค. Fig. 3์œผ๋กœ๋ถ€ํ„ฐ ํŒŒํ˜•๊ฒฝ์‚ฌ๊ฐ€ ํด ๋•Œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ํฌ๊ณ , ์ƒ๋Œ€์ƒ๋‹จํญ์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ๊ฐ์†Œํ•จ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์ƒ๋Œ€์ƒ๋‹จํญ์ด ์ผ์ •๊ฐ’ ์ด์ƒ ์ฆ๊ฐ€ํ•˜๊ฒŒ ๋˜๋ฉด, ์ฆ‰ W / L 0 > 0.7์—์„œ๋Š” ์Œ(-)์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ์‚ฐ์ •๋œ๋‹ค. ์ด๋Š” Takayama et al.(1985)์˜ ์‹คํ—˜์€ ์ƒ๋Œ€์ƒ๋‹จํญ์ด ์ž‘์€ ๊ฒฝ์šฐ( W / L 0 <0.4)์— ๋Œ€ํ•œ ๊ฒฐ๊ณผ์ด๊ธฐ ๋•Œ๋ฌธ์ด๋ฉฐ, ์ƒ๋Œ€์ƒ๋‹จํญ์ด ํฐ ๊ฒฝ์šฐ์—๋Š” ๊ทธ๋ฆ‡๋œ ๊ฒฐ๊ณผ๋ฅผ ์ œ์‹œํ•  ์ˆ˜ ์žˆ๋‹ค. Takayama et al.(1985)์˜ ์ œ์•ˆ์‹์€ ์ฃผ๊ธฐ๊ฐ€ ์ƒ๋Œ€์ ์œผ๋กœ ๊ธด ์„ค๊ณ„ํŒŒ ์กฐ๊ฑด์—์„œ๋Š” ์ ์šฉ์— ๋ฌธ์ œ๊ฐ€ ์—†์„ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋˜์ง€๋งŒ, ์ฃผ๊ธฐ๊ฐ€ ์ƒ๋Œ€์ ์œผ๋กœ ์งง์€ ํŒŒ๋ž‘์— ์˜ํ•œ ์˜ํ–ฅ์„ ๊ฒ€ํ† ํ•˜๊ธฐ์—๋Š” ๋ถ€์ ์ ˆํ•˜๋‹ค๊ณ  ์ƒ๊ฐ๋œ๋‹ค.

Figure_KSCE_40_05_05_F3.jpg
Fig. 3.

Wave Transmission Coefficients of Takayama et al.(1985)

3. ์‹คํ—˜์‹œ์„ค ๋ฐ ์‹คํ—˜์กฐ๊ฑด

3.1 ์‹คํ—˜์‹œ์„ค

๋ณธ ์‹คํ—˜์€ ์ „๋‚จ๋Œ€ํ•™๊ต ํ•ด์•ˆํ•ญ๋งŒ์‹คํ—˜์„ผํ„ฐ ๋‹จ๋ฉด์ˆ˜๋กœ์—์„œ ์ˆ˜ํ–‰๋˜์—ˆ์œผ๋ฉฐ, ์‚ฌ์šฉ๋œ ๋‹จ๋ฉด์ˆ˜๋กœ์˜ ์ œ์›์€ ํญ 1 m, ๊ธธ์ด 50 m, ๋†’์ด 1.3 m์ด๋ฉฐ, ์ „๊ธฐ์„œ๋ณดํ”ผ์Šคํ†ค์‹ ์กฐํŒŒ๊ธฐ๊ฐ€ ์„ค์น˜๋˜์–ด ์žˆ๊ณ , ๊ทœ์น™ํŒŒ ๋ฐ ๋ถˆ๊ทœ์น™ํŒŒ๋ฅผ ์กฐํŒŒํ•  ์ˆ˜ ์žˆ๋‹ค. ๋˜ํ•œ ์กฐํŒŒํŒ ์ „๋ฉด์— ๋ถ€์ฐฉ๋œ ํŒŒ๊ณ ๊ณ„๋ฅผ ์ด์šฉํ•˜์—ฌ ๋…์ทจํ•œ ์ž๋ฃŒ๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ ๋ฐ˜์‚ฌํŒŒ ํก์ˆ˜์‹ ์ œ์–ด๊ฐ€ ๊ฐ€๋Šฅํ•˜๊ณ  ์ˆ˜๋กœ ์–‘์ชฝ ๋๋ถ€๋ถ„์— ์†ŒํŒŒ์‹œ์„ค์ด ์„ค์น˜๋˜์–ด ์žˆ๋‹ค. ์„ค์น˜๋œ ์กฐํŒŒ๊ธฐ์˜ ์„ฑ๋Šฅ์€ ์ตœ๋Œ€ํŒŒ๊ณ  0.7 m, ์žฌํ˜„๊ฐ€๋Šฅ ์ฃผ๊ธฐ 0.5~8 sec์ด๋‹ค. Fig. 4๋Š” ๋‹จ๋ฉด์ˆ˜๋กœ์˜ ๊ฐœ๋…๋„์ด๋‹ค. ๋ณธ ์‹คํ—˜์—์„œ ์ž์œ ์ˆ˜๋ฉด๊ณ„์ธก์— ํ™œ์šฉ๋œ ํŒŒ๊ณ ๊ณ„๋Š” ์šฉ๋Ÿ‰์‹์œผ๋กœ์„œ ์ „์ฒด 12๋Œ€์˜ ํŒŒ๊ณ ๊ณ„๋ฅผ ์„ค์น˜ํ•˜์—ฌ ๊ณ„์ธกํ•˜์˜€๋‹ค. ํŒŒ๊ณ ๊ณ„ 2๋Œ€๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์ „๋ฉด์— ์„ค์น˜ํ•˜์—ฌ ์ž…์‚ฌํŒŒ ํ™•์ธ ๋ฐ ๋ฐ˜์‚ฌ๊ณ„์ˆ˜๋ฅผ ๋ถ„์„ํ•˜์˜€์œผ๋ฉฐ, 10๋Œ€์˜ ํŒŒ๊ณ ๊ณ„๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์ƒ๋ถ€ ๋ฐ ํ›„๋ฉด์— ์„ค์น˜ํ•˜์—ฌ ์ž์œ ์ˆ˜๋ฉด์„ ๊ณ„์ธกํ•˜๊ณ , ํŒŒ๊ณ ๋ฅผ ๋ถ„์„ํ•˜๋Š”๋ฐ ํ™œ์šฉ๋˜์—ˆ๋‹ค.

Figure_KSCE_40_05_05_F4.jpg
Fig. 4.

Experimental Facilities

3.2 ์‹คํ—˜์กฐ๊ฑด

๋ณธ ์‹คํ—˜์— ์ ์šฉ๋œ ์‹คํ—˜ํŒŒ ๋ฐ ์‹คํ—˜์ˆ˜์‹ฌ์€ Table 1์— ์ œ์‹œ๋˜์–ด ์žˆ๋Š” ๋ฐ”์™€ ๊ฐ™์ด ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์ด ์„ค์น˜๋˜๋Š” ์ˆ˜์‹ฌ( d )์€ d =0.2 m, 0.3 m, 0.4 m์ด๋‹ค. ์‹คํ—˜ํŒŒ์˜ ์œ ์˜์ฃผ๊ธฐ( T s ) ๋ฐ ์œ ์˜ํŒŒ๊ณ ( H S )๋Š” ๊ฐ๊ฐ T s =1.0~3.0 sec, H S =0.04~0.14 m ๋ฒ”์œ„์ด๋ฉฐ, ์œ ์˜์ฃผ๊ธฐ๋Š” ฮ” T s =0.2 sec ๊ฐ„๊ฒฉ, ์œ ์˜ํŒŒ๊ณ ๋Š” ฮ” H s =0.02 m ๊ฐ„๊ฒฉ์œผ๋กœ ์„ค์ •ํ•˜์˜€๋‹ค. Table 1์— ์ œ์‹œ๋œ ํŒŒ๋ž‘์ œ์›์€ ๋ชฉํ‘œ ํŒŒ๋ž‘์ œ์›์ด๋ฉฐ, ์‹คํ—˜๊ฒฐ๊ณผ ๋ถ„์„์‹œ์—๋Š” ์„ค์ •๋œ ์‹คํ—˜ํŒŒ ์ œ์›์„ ์ด์šฉํ•˜์˜€๋‹ค. ์‹คํ—˜ํŒŒ๋Š” ๋ชฉํ‘œ ํŒŒ๋ž‘์ œ์›์— ์ตœ๋Œ€ํ•œ ๊ทผ์ ‘ํ•˜๋„๋ก ๋ฐ˜๋ณตํ•˜์—ฌ ์„ค์ •ํ•˜์˜€์œผ๋ฉฐ, ๊ตญํ† ๊ตํ†ต์—ฐ๊ตฌ์ธํ”„๋ผ์šด์˜์›(KOCED, 2019)์—์„œ ์ œ์‹œํ•œ ์„ค์ •๋ฐฉ๋ฒ•์„ ์ด์šฉํ•˜์˜€๋‹ค. ๋ณธ ์‹คํ—˜์— ์ ์šฉ๋œ ์‹คํ—˜๋‹จ๋ฉด์€ Fig. 5์™€ ๊ฐ™๋‹ค. Fig. 5์—์„œ d ๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์„ ๋‹จ์—์„œ์˜ ์„ค์น˜์ˆ˜์‹ฌ, R C ๋Š” ์—ฌ์œ ๊ณ (์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์ƒ๋‹จ์œผ๋กœ๋ถ€ํ„ฐ ์ •์ˆ˜๋ฉด๊นŒ์ง€์˜ ๋†’์ด), W ๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ƒ๋‹จํญ, A T ๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ํ”ผ๋ณต์žฌ ๋†’์ด, h s ๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ „์ฒด ๋†’์ด์ด๋‹ค. ๋ณธ ์‹คํ—˜์—์„œ๋Š” ํ”ผ๋ณต์žฌ๋กœ Tetrapod๋ฅผ ํ™œ์šฉํ•˜์˜€๋‹ค. ๊ธฐ์กด ์„ค๊ณ„์‚ฌ๋ก€๋ฅผ ์‚ดํŽด๋ณด๋ฉด ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์ด ์„ค์น˜๋˜๋Š” ์ˆ˜์‹ฌ์€ ๊นŠ์ง€ ์•Š๊ธฐ ๋•Œ๋ฌธ์— ํ”ผ๋ณต์žฌ์˜ ์‚ฌ๋ฉด๊ฒฝ์‚ฌ์— ๋”ฐ๋ฅธ ๋ณ€ํ™”๋Š” ํฌ์ง€ ์•Š์„ ๊ฒƒ์œผ๋กœ ํŒ๋‹จํ•˜์—ฌ ๋ณธ ์‹คํ—˜์—์„œ๋Š” ํ”ผ๋ณต์žฌ์˜ ์‚ฌ๋ฉด๊ฒฝ์‚ฌ๋ฅผ 1:1.5๋กœ ๊ณ ์ •ํ•˜์˜€๋‹ค.

Table 1.

Target Wave Conditions and Water Depths

Water depth at toe
( d , m)
Significant wave period
( T s , sec)
Significant wave height
( H s , m)
Remarks
0.2 1.0~3.0 0.04~0.10 โˆ† T S = 0 . 2   s e c
โˆ† H S = 0 . 02   m
Bretschneider-Mitsuyasu frequency spectrum
0.3 0.4 1.0~3.0 0.06~0.14
Figure_KSCE_40_05_05_F5.jpg
Fig. 5.

Schematic of Model Structure

Table 2๋Š” ๋ณธ ์‹คํ—˜์—์„œ ์ ์šฉํ•œ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ œ์›์„ ์ •๋ฆฌํ•œ ๊ฒƒ์ด๋‹ค(Fig. 5 ์ฐธ์กฐ). ๊ฐ ์„ค์น˜์ˆ˜์‹ฌ๋ณ„๋กœ ์—ฌ์œ ๊ณ ์™€ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ํญ์„ ๋‹ฌ๋ฆฌํ•˜์˜€์œผ๋ฉฐ, ์ด๋Š” ์ƒ๋Œ€์—ฌ์œ ๊ณ  ๋ฐ ์ƒ๋Œ€์ƒ๋‹จํญ์— ๋”ฐ๋ฅธ ๋ณ€ํ™”๋ฅผ ๊ฒ€ํ† ํ•˜๊ธฐ ์œ„ํ•จ์ด๋‹ค. ๋ณธ ์‹คํ—˜์€ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์ด Tetrapod๋กœ ๊ตฌ์„ฑ๋œ ํˆฌ๊ณผํ˜• ๊ตฌ์กฐ๋ฌผ์— ๋Œ€ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ๋ถ„์„์„ ๋ชฉ์ ์œผ๋กœ ์ˆ˜ํ–‰๋˜์—ˆ๋‹ค. ์‹คํ—˜์—๋Š” 2๊ฐ€์ง€ ํฌ๊ธฐ( D n =0.042 m, D n =0.074 m)์˜ Tetrapod๋ฅผ ์ ์šฉํ•˜์˜€์œผ๋ฉฐ, ์ด๋Š” ๊ณต๊ทน์œจ์€ ์œ ์‚ฌํ•˜์ง€๋งŒ ํ”ผ๋ณต์žฌ์˜ ํฌ๊ธฐ์— ๋”ฐ๋ฅธ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜์˜ ๋ณ€ํ™”๋ฅผ ๋ถ„์„ํ•˜๊ธฐ ์œ„ํ•œ ๊ฒƒ์ด๋‹ค. ์—ฌ๊ธฐ์„œ, D n ์€ ๊ณต์นญ๊ธธ์ด(nominal length)๋กœ์„œ D n = V 1 / 3 ์ด๋ฉฐ, V ๋Š” Tetrapod์˜ ์ฒด์ ์ด๋‹ค. ๋ณธ ์‹คํ—˜์—์„œ๋Š” Tetrapod๋ฅผ 2์ธต ๋ฐ 4์ธต์œผ๋กœ ํ”ผ๋ณตํ•จ์œผ๋กœ์„œ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ๋†’์ด( A T )๋ฅผ A T =0.09 m, 0.17 m, 0.18 m, 0.32 m๋กœ ๋ณ€ํ™”์‹œ์ผฐ๋‹ค. Fig. 6์€ ๋ณธ ์‹คํ—˜์— ์ ์šฉ๋œ ๋ชจํ˜•์„ค์น˜ ์‚ฌ์ง„์ด๋‹ค.

Table 2.

Parameters of Test Cases

Water depth d (m) Freeboard over submerged structure R C (m) Crest width of submerged structure W (m) Remarks
0.2 0.11 0.25, 0.5, 1, 2 Tetrapod (2 layers)
D n =0.042 m, A T =0.09 m
0.2 0.3 0.02, 0.12 0.25, 0.5, 1, 2 Tetrapod (4 layers)
D n =0.042 m, A T =0.18 m
0.2 0.3 0.03, 0.13 0.25, 0.5, 1, 2 Tetrapod (2 layers)
D n =0.074 m, A T =0.17 m
0.4 0.08 0.25, 0.5, 1, 2 Tetrapod (4 layers)
D n =0.074 m, A T =0.32 m
Figure_KSCE_40_05_05_F6.jpg
Fig. 6.

Photographs of Model Setup

4. ์‹คํ—˜๊ฒฐ๊ณผ ๋ถ„์„

4.1 ์ƒ๋Œ€ํŒŒ๊ณ  ๊ณ„์ธก๊ฒฐ๊ณผ ๋ฐ ์ „๋‹ฌํŒŒ๊ณ  ์‚ฐ์ •๋ฐฉ๋ฒ•

๋ณธ ์—ฐ๊ตฌ๋Š” Tables 1 and 2์— ์ œ์‹œ๋œ ์กฐ๊ฑด์œผ๋กœ 2์ฐจ์› ์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜์—ฌ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ๋‹ค์–‘ํ•œ ์ œ์›์— ๋”ฐ๋ฅธ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜์˜ ๋ณ€ํ™”๋ฅผ ๊ฒ€ํ† ํ•˜๋Š” ๊ฒƒ์ด ์ฃผ๋œ ๋ชฉ์ ์ด๋‹ค. 2์ฐจ์› ์‹คํ—˜์œผ๋กœ๋ถ€ํ„ฐ ๋„์ถœ๋œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์ž์ฒด์— ์˜ํ•œ ํŒŒ๋ž‘๊ฐ์‡  ํšจ๊ณผ๋งŒ์ด ๋ฐ˜์˜๋œ ๊ฒฐ๊ณผ์ด๋ฉฐ, ์‹ค์ œ ํ•ด์—ญ์—์„œ์™€ ๊ฐ™์ด ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ๊ฐ„์˜ ์ด๊ฒฉ(๊ฐœ๊ตฌ๋ถ€)์ด ์กด์žฌํ•˜๋Š” ๊ฒฝ์šฐ์—๋Š” ๊ฐœ๊ตฌ๋ถ€์—์„œ ํšŒ์ ˆ๋œ ํŒŒ๋ž‘์œผ๋กœ ์ธํ•ด ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ๋ฐฐํ›„๋ฉด์—๋Š” ๋ณด๋‹ค ํฐ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ๋ฐœ์ƒํ•  ์ˆ˜ ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์ด๋Ÿฌํ•œ ํšจ๊ณผ๋ฅผ ๊ฒ€ํ† ํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” 3์ฐจ์› ์ˆ˜๋ฆฌ์‹คํ—˜์ด ํ•„์š”ํ•˜๋‹ค. ๋ณธ ์—ฐ๊ตฌ์—์„œ ๊ณ„์ธกํŒŒ๊ณ  ๋ถ„์„์€ ์˜์ ์ƒํ–ฅ๊ต์ฐจ๋ฒ•(zero-up crossing method)์„ ์ด์šฉํ•˜์˜€์œผ๋ฉฐ, ํŒŒ๋ž‘์ด ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์„ ํ†ต๊ณผํ•˜๋ฉด์„œ ๋ฐœ์ƒํ•˜๋Š” ์‡„ํŒŒ ๋“ฑ์œผ๋กœ ์ธํ•œ ์ˆ˜์œ„์ƒ์Šน์€ filtering๊ธฐ๋ฒ•์„ ์ด์šฉํ•˜์—ฌ ์ œ๊ฑฐํ•˜์˜€๋‹ค.

Fig. 7์€ D n =0.042 m์˜ Tetrapod๋ฅผ ์ ์šฉํ•œ ์‹คํ—˜์กฐ๊ฑด ์ค‘ ์ผ๋ถ€ ์กฐ๊ฑด์— ๋Œ€ํ•œ ๊ณ„์ธก์ ์—์„œ์˜ ์ƒ๋Œ€ํŒŒ๊ณ  ๊ฒฐ๊ณผ๋ฅผ ๋„์‹œํ•œ ๊ฒƒ์œผ๋กœ์„œ ์ƒ๋Œ€ํŒŒ๊ณ ๋Š” ๊ณ„์ธก๋œ ์œ ์˜ํŒŒ๊ณ ( ( H S ) m )์™€ ์ž…์‚ฌํŒŒ๊ณ (์‹คํ—˜ํŒŒ ์„ค์ •์‹œ์˜ ์œ ์˜ํŒŒ๊ณ , H S )์˜ ๋น„์ด๋‹ค. Figs. 7(a) and 7(b)๋Š” R C =0.02 m์˜ ๊ฒฐ๊ณผ๋กœ์„œ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์ „๋ฉด์œ„์น˜์—์„œ๋Š” ์ˆ˜์‹ฌ๊ฐ์†Œ๋กœ ์ธํ•ด ์ƒ๋Œ€ํŒŒ๊ณ ๊ฐ€ ๊ธ‰๊ฒฉํ•˜๊ฒŒ ์ฆ๊ฐ€ํ•˜์ง€๋งŒ, ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ํ›„๋ฉด์—์„œ๋Š” ์‡„ํŒŒํ˜„์ƒ์œผ๋กœ ์ธํ•ด ์ƒ๋Œ€ํŒŒ๊ณ ๋Š” ๊ธ‰๊ฒฉํžˆ ๊ฐ์†Œํ•˜๋ฉฐ, ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ํญ์ด ๋„“์€ ๊ฒฝ์šฐ์— ํŒŒ๋ž‘๊ฐ์‡ ํšจ๊ณผ๊ฐ€ ์ƒ๋Œ€์ ์œผ๋กœ ์šฐ์ˆ˜ํ•จ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. Figs. 7(c) and (d)๋Š” R C =0.12 m์˜ ๊ฒฐ๊ณผ๋กœ์„œ ์ž…์‚ฌํŒŒ๊ณ ( H S )์— ๋น„ํ•ด ์—ฌ์œ ๊ณ ( R C )๊ฐ€ ํผ์œผ๋กœ ์ธํ•ด ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์œ„์น˜์—์„œ์˜ ํŒŒ๊ณ ์ฆํญ ๋ฐ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์— ์˜ํ•œ ํŒŒ๊ณ ๊ฐ์‡  ํšจ๊ณผ๊ฐ€ R C =0.02 m์ธ ๊ฒฝ์šฐ์— ๋น„ํ•ด ํฌ์ง€ ์•Š์Œ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. ์ „์ฒด์ ์œผ๋กœ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ํ›„๋ฉด ์„ ๋‹จ์œผ๋กœ๋ถ€ํ„ฐ ์•ฝ 0.4 ํŒŒ์žฅ( x / L S โ‰ฅ0.4) ์ดํ›„์˜ ์œ„์น˜์—์„œ๋Š” ์‹คํ—˜ํŒŒ ์กฐ๊ฑด์— ๊ด€๊ณ„ ์—†์ด ์ƒ๋Œ€ํŒŒ๊ณ ๊ฐ€ ์œ ์‚ฌํ•˜๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

Figure_KSCE_40_05_05_F7.jpg
Fig. 7.

Relative Wave Heights at Measuring Points for D n =0.042 m

Fig. 8์€ D n =0.074 m์˜ Tetrapod๋ฅผ ์ ์šฉํ•œ ์‹คํ—˜์กฐ๊ฑด ์ค‘ ์ผ๋ถ€ ์กฐ๊ฑด์— ๋Œ€ํ•œ ๊ณ„์ธก์ ์—์„œ์˜ ์ƒ๋Œ€ํŒŒ๊ณ  ๊ฒฐ๊ณผ๋ฅผ ๋„์‹œํ•œ ๊ฒƒ์œผ๋กœ์„œ ์ „๋ฐ˜์ ์ธ ๊ฒฝํ–ฅ์€ Fig. 7๊ณผ ์œ ์‚ฌํ•˜๋‹ค. Figs. 8(c) and 8(d)๋Š” R C =0.08 m์˜ ๊ฒฐ๊ณผ๋กœ์„œ ์ƒ๋Œ€์—ฌ์œ ๊ณ ( R C / H S )๊ฐ€ ํด์ˆ˜๋ก ํŒŒ๊ณ ์ €๊ฐ ํšจ๊ณผ๊ฐ€ ๋‚ฎ์Œ์„ ์•Œ ์ˆ˜ ์žˆ์œผ๋ฉฐ, ์ƒ๋Œ€์—ฌ์œ ๊ณ ๊ฐ€ ํฐ ๊ฒฝ์šฐ์—๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ํญ์ด ๋„“๋”๋ผ๋„ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ํ›„๋ฉด์—์„œ ๋น„๊ต์  ํฐ ์ƒ๋Œ€ํŒŒ๊ณ ๊ฐ€ ๊ณ„์ธก๋˜์—ˆ๋‹ค. ์ด๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์ƒ๋‹จ์—์„œ์˜ ์‡„ํŒŒํ˜„์ƒ ์œ ๋„๋ฅผ ํ†ตํ•ด ํŒŒ๋ž‘์—๋„ˆ์ง€์˜ ์ €๊ฐ์‹œํ‚ค๋Š” ํšจ๊ณผ๊ฐ€ ์ž‘๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค. ์ฆ‰, R C / H S >1์ธ ๊ฒฝ์šฐ์—๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์— ์˜ํ•œ ํŒŒ๊ณ ์ €๊ฐํšจ๊ณผ๊ฐ€ ํฌ์ง€ ์•Š์„ ๊ฒƒ์œผ๋กœ ์ถ”์ธกํ•  ์ˆ˜ ์žˆ๋‹ค. Fig. 7๊ณผ ๋งˆ์ฐฌ๊ฐ€์ง€๋กœ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ํ›„๋ฉด ์„ ๋‹จ์œผ๋กœ๋ถ€ํ„ฐ ์•ฝ 0.4 ํŒŒ์žฅ(   x / L S โ‰ฅ0.4) ์ดํ›„์˜ ์œ„์น˜์—์„œ๋Š” ์‹คํ—˜ํŒŒ ์กฐ๊ฑด์— ๊ด€๊ณ„ ์—†์ด ์ƒ๋Œ€ํŒŒ๊ณ ๊ฐ€ ์œ ์‚ฌํ•˜๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

Figure_KSCE_40_05_05_F8.jpg
Fig. 8.

Relative Wave Heights at Measuring Points for D n =0.074 m

Figs. 7 and 8์˜ ์ƒ๋Œ€ํŒŒ๊ณ  ๋ถ„ํฌ๊ฒฐ๊ณผ๋ฅผ ์‚ดํŽด ๋ณผ ๋•Œ, ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ํ›„๋ฉด ์„ ๋‹จ์œผ๋กœ๋ถ€ํ„ฐ   x / L S โ‰ฅ0.4 ๋ฒ”์œ„์—์„œ๋Š” ์ƒ๋Œ€ํŒŒ๊ณ ๊ฐ€ ์•ˆ์ •ํ™” ๋˜๋Š” ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค. ๋”ฐ๋ผ์„œ ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” 0.4โ‰ค x / L S โ‰ค1 ๋ฒ”์œ„์— ์œ„์น˜ํ•˜๋Š” ๊ณ„์ธกํŒŒ๊ณ ๋ฅผ ํ‰๊ท ํ•œ ํŒŒ๊ณ ์™€ ์ž…์‚ฌํŒŒ๊ณ ์˜ ๋น„๋กœ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ์‚ฐ์ •ํ•˜์˜€๋‹ค.

4.2 D n =0.042 m ์กฐ๊ฑด์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •

๋ณธ ์ ˆ์—์„œ๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ œ์ฒดํ˜•์„ฑ์— ์‚ฌ์šฉ๋œ Tetrapod์˜ ๊ณต์นญ๊ธธ์ด๊ฐ€ D n =0.042 m์ธ ๊ฒฝ์šฐ์— ๋Œ€ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •๊ฒฐ๊ณผ๋ฅผ ๊ฒ€ํ† ํ•˜์˜€๋‹ค.

Fig. 9๋Š” ์ž…์‚ฌํŒŒ์˜ ํŒŒํ˜•๊ฒฝ์‚ฌ( H S / L S )์— ๋”ฐ๋ฅธ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜( K T )์˜ ๋ณ€ํ™”๋ฅผ ๋„์‹œํ•œ ๊ฒƒ์ด๋‹ค. ์ „์ฒด์ ์œผ๋กœ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ƒ๋Œ€์ƒ๋‹จํญ( W / L S )์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋Š” ๊ฐ์†Œํ•˜๋ฉฐ, W / L S >0.8์—์„œ๋Š” ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋Š” ๊ฑฐ์˜ ์ผ์ •ํ•œ ๊ฐ’์„ ๋ณด์ธ๋‹ค. Fig. 9(a)๋Š” ์ƒ๋Œ€์—ฌ์œ ๊ณ  R C / H S =0.2 ์กฐ๊ฑด์˜ ๊ฒฐ๊ณผ๋กœ์„œ ํŒŒํ˜•๊ฒฝ์‚ฌ์— ๋”ฐ๋ฅธ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋Š” ์œ ์‚ฌํ•˜๊ฒŒ ๋‚˜ํƒ€๋‚ฌ์œผ๋ฉฐ, ์‹คํ—˜๊ฒฐ๊ณผ์™€ ํšŒ๊ท€์‹์˜ ์ƒ๊ด€๊ณ„์ˆ˜( R 2 )๋Š” 0.98์ด๋‹ค. ์ฆ‰, ์ƒ๋Œ€์—ฌ์œ ๊ณ ๊ฐ€ ์ž‘์€ ๊ฒฝ์šฐ์—๋Š” ํŒŒํ˜•๊ฒฝ์‚ฌ์— ๋”ฐ๋ฅธ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜์˜ ๋ณ€ํ™”๋Š” ํฌ์ง€ ์•Š์Œ์„ ์˜๋ฏธํ•˜๋ฉฐ, ์ด๋Š” Figs. 7(a) and (b)์— ๋„์‹œ๋œ ๋ฐ”์™€ ๊ฐ™์ด ์ƒ๋‹จ์—ฌ์œ ๊ณ ( R C )๊ฐ€ ์ž‘์€ ๊ฒฝ์šฐ์—๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์ƒ๋‹จ์—์„œ ์‡„ํŒŒ๊ฐ€ ๊ฐ•ํ•˜๊ฒŒ ๋ฐœ์ƒํ•จ์œผ๋กœ ์ธํ•ด ์ž…์‚ฌํŒŒ๊ณ ์˜ ํฌ๊ธฐ์— ๋”ฐ๋ฅธ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜์˜ ๋ณ€ํ™”๋Š” ํฌ์ง€ ์•Š์Œ์„ ์˜๋ฏธํ•œ๋‹ค. Fig. 9(b)๋Š”   R C / H S =0.5 ์กฐ๊ฑด์˜ ๊ฒฐ๊ณผ๋กœ์„œ ํŒŒํ˜•๊ฒฝ์‚ฌ๊ฐ€ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ํฌ๊ฒŒ ๋‚˜ํƒ€๋‚ฌ์œผ๋ฉฐ, ์ด๋Š” Takayama et al.(1985)์˜ ๊ฒฐ๊ณผ์™€ ์ผ์น˜ํ•˜๋Š” ํ˜„์ƒ์ด๋‹ค(Fig. 3 ์ฐธ์กฐ). Fig. 9(b)์—์„œ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ํšŒ๊ท€์‹์˜ ์ƒ๊ด€๊ณ„์ˆ˜๋Š” H S / L S =0.010~0.012์ธ ๊ฒฝ์šฐ์— R 2 =0.98, H S / L S =0.013~ 0.017์ธ ๊ฒฝ์šฐ์— R 2 =0.99, H S / L S =0.019~0.033์ธ ๊ฒฝ์šฐ์— R 2 =0.98์ด๋‹ค. ํŒŒํ˜•๊ฒฝ์‚ฌ์— ๋”ฐ๋ฅธ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜์˜ ๋ณ€ํ™”๋ฅผ ์‚ดํŽด๋ณด๊ธฐ ์œ„ํ•œ ๊ตฌ๊ฐ„์„ค์ •์€ R 2 >0.95๊ฐ€ ๋˜๋Š” ๊ตฌ๊ฐ„์œผ๋กœ ์„ค์ •ํ•˜์˜€๋‹ค.

Figure_KSCE_40_05_05_F9.jpg
Fig. 9.

Wave Transmission Coefficients by Wave Steepness for R C / d =0.1 & D n =0.042 m

Tetrapod์˜ ๊ณต์นญ๊ธธ์ด๊ฐ€ D n =0.042 m์ธ ๊ฒฝ์šฐ์˜ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ์ด์šฉํ•˜์—ฌ ๋‹ค์ค‘ํšŒ๊ท€๋ถ„์„์„ ์‹ค์‹œํ•˜์˜€๊ณ , ๋„์ถœ๋œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์‹์€ Eq. (2)์™€ ๊ฐ™๋‹ค. ๊ฒฝํ—˜์‹์€ R C / d , R C / H S , H S / L S ๋ฐ W / L S ๋ฅผ ํ•จ์ˆ˜๋กœ ํ•œ ์„ ํ˜•์‹์œผ๋กœ ๋„์ถœํ•˜์˜€์œผ๋ฉฐ, ์‹คํ—˜๊ฒฐ๊ณผ์™€ ๊ฒฝํ—˜์‹๊ฐ„์˜ ์ƒ๊ด€๊ณ„์ˆ˜( R 2 )๋Š” 0.97์ด๋‹ค.

$$K_T=0.395\;\exp\left(\frac{R_C}d\right)+0.101\;\exp\left(\frac{R_C}{H_S}\right)+0.081\;\ln\left(\frac{H_S}{L_S}\right)-0.210\;\ln\left(\frac W{L_S}\right)-0.050$$ (2)

Fig. 10์€ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ๊ฒฝํ—˜์‹์— ์˜ํ•œ ๊ฒฐ๊ณผ๋ฅผ ๋น„๊ต ๋„์‹œํ•œ ๊ฒƒ์œผ๋กœ์„œ ์ „์ฒด์ ์œผ๋กœ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ์‚ฐ์ •์‹์— ์˜ํ•œ ๊ฒฐ๊ณผ๊ฐ€ ์ž˜ ์ผ์น˜ํ•˜๋ฉฐ, ์ƒ๋Œ€์—ฌ์œ ๊ณ ( R C / H S )๊ฐ€ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ํŒŒํ˜•๊ฒฝ์‚ฌ์— ๋”ฐ๋ฅธ ๋ณ€ํ™”๊ฐ€ ํผ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. W / L S โ‰ฅ0.9์ด๊ณ  ํŒŒํ˜•๊ฒฝ์‚ฌ๊ฐ€ ์ž‘์€ ์กฐ๊ฑด์—์„œ๋Š” ์‚ฐ์ •์‹์— ์˜ํ•œ ๊ฒฐ๊ณผ๊ฐ€ ์‹คํ—˜๊ฒฐ๊ณผ๋ณด๋‹ค ์ž‘๊ฒŒ ๋‚˜ํƒ€๋‚ฌ์œผ๋ฉฐ, ์ด๋Ÿฌํ•œ ํ˜„์ƒ์€ R C / H S ๊ฐ€ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ๋šœ๋ ทํ•˜๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ๊ธฐ์กด ์„ค๊ณ„์‚ฌ๋ก€ ๋ถ„์„์—์„œ ๋‚˜ํƒ€๋‚œ ๋ฐ”์™€ ๊ฐ™์ด W / L S โ‰ค0.6์ด๊ณ , H S / L S โ‰ฅ0.03์ธ ์กฐ๊ฑด์ด ๋Œ€๋ถ€๋ถ„์ด๊ธฐ ๋•Œ๋ฌธ์— ๋ณธ ์‚ฐ์ •์‹์˜ ์ ์šฉ์„ฑ์€ ์ถฉ๋ถ„ํ•˜๋‹ค๊ณ  ํŒ๋‹จ๋œ๋‹ค.

Figure_KSCE_40_05_05_F10.jpg
Fig. 10.

Wave Transmission Coefficients as a Function of the Relative Crest Width (   W / L S ) According to the Different Values of R C / H S for R C / d =0.1 & D n =0.042 m. Open Circles Indicate Experimental Data. Solid and Dashed Lines Indicate the Results of the Empirical Formula [Eq. (2)]

Fig. 11์€ ๋ณธ ์—ฐ๊ตฌ์—์„œ ์ˆ˜ํ–‰ํ•œ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ์‚ฐ์ •์‹์— ์˜ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ๋น„๊ต ๋„์‹œํ•œ ๊ฒƒ์œผ๋กœ์„œ ๋น„๊ต์  ์ž˜ ์ผ์น˜ํ•˜๊ณ  ์žˆ์Œ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค.

Figure_KSCE_40_05_05_F11.jpg
Fig. 11.

Comparison between Measured Data and Empirical Formula [Eq. (2)] for D n =0.042 m

4.3 D n =0.074 m ์กฐ๊ฑด์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •

๋ณธ ์ ˆ์—์„œ๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ œ์ฒดํ˜•์„ฑ์— ์‚ฌ์šฉ๋œ Tetrapod์˜ ๊ณต์นญ๊ธธ์ด๊ฐ€ D n =0.074 m์ธ ๊ฒฝ์šฐ์— ๋Œ€ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •๊ฒฐ๊ณผ๋ฅผ ๊ฒ€ํ† ํ•˜์˜€๋‹ค.

Fig. 12๋Š” ์ž…์‚ฌํŒŒ๋ž‘์˜ ํŒŒํ˜•๊ฒฝ์‚ฌ( H S / L S )์— ๋”ฐ๋ฅธ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜( K T )์˜ ๋ณ€ํ™”๋ฅผ ๋„์‹œํ•œ ๊ฒƒ์œผ๋กœ์„œ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ƒ๋Œ€์ƒ๋‹จํญ( W / L S )์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋Š” ๊ฐ์†Œํ•˜๊ณ , W / L S >0.8์—์„œ๋Š” ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ๊ฑฐ์˜ ์ผ์ •ํ•œ ๊ฐ’์„ ๋ณด์ด๋Š” ๊ฒฝํ–ฅ์€ D n =0.042 m์ธ ๊ฒฝ์šฐ์™€ ์œ ์‚ฌํ•˜๋‹ค. Fig. 12(a)๋Š” ์ƒ๋Œ€์—ฌ์œ ๊ณ  R C / H S =0.3 ์กฐ๊ฑด์˜ ๊ฒฐ๊ณผ๋กœ์„œ Fig. 9(a)๋ณด๋‹ค๋Š” ๋ถ„์‚ฐ์ด ํฌ์ง€๋งŒ ํŒŒํ˜•๊ฒฝ์‚ฌ์— ๋”ฐ๋ฅธ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋Š” ์œ ์‚ฌํ•˜๊ฒŒ ๋‚˜ํƒ€๋‚ฌ์œผ๋ฉฐ, ์‹คํ—˜๊ฒฐ๊ณผ์™€ ํšŒ๊ท€์‹์˜ ์ƒ๊ด€๊ณ„์ˆ˜( R 2 )๋Š” 0.97์ด๋‹ค. Fig. 12(b)๋Š” R C / H S =0.5 ์กฐ๊ฑด์˜ ๊ฒฐ๊ณผ๋กœ์„œ ํŒŒํ˜•๊ฒฝ์‚ฌ๊ฐ€ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ํฌ๊ฒŒ ๋‚˜ํƒ€๋‚ฌ์œผ๋ฉฐ, ์ด๋Š” D n =0.042 m ์กฐ๊ฑด์˜ ๊ฒฐ๊ณผ์™€ ์ผ์น˜ํ•˜๋Š” ํ˜„์ƒ์ด๋‹ค. Fig. 9(b)์—์„œ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ํšŒ๊ท€์‹์˜ ์ƒ๊ด€๊ณ„์ˆ˜๋Š” H S / L S =0.015~0.017์ธ ๊ฒฝ์šฐ์— R 2 =0.99, H S / L S =0.018~0.025์ธ ๊ฒฝ์šฐ์— R 2 =0.97, H S / L S =0.028~0.039์ธ ๊ฒฝ์šฐ์— R 2 =0.96, H S / L S =0.050์ธ ๊ฒฝ์šฐ์— R 2 =0.99์ด๋‹ค.

Figure_KSCE_40_05_05_F12.jpg
Fig. 12.

Wave Transmission Coefficients by Wave Steepness for R C / d =0.15 & D n =0.074 m

Tetrapod์˜ ๊ณต์นญ๊ธธ์ด๊ฐ€ D n =0.074 m์ธ ๊ฒฝ์šฐ์˜ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ์ด์šฉํ•˜์—ฌ ๋‹ค์ค‘ํšŒ๊ท€๋ถ„์„์„ ์‹ค์‹œํ•˜์˜€๊ณ , ๋„์ถœ๋œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์‹์€ Eq. (3)๊ณผ ๊ฐ™๋‹ค. ๋ถ„์„๋ฐฉ๋ฒ•์€ D n =0.042 m์ธ ๊ฒฝ์šฐ์™€ ๋™์ผํ•˜๋ฉฐ, ์‹คํ—˜๊ฒฐ๊ณผ์™€ ๊ฒฝํ—˜์‹๊ฐ„์˜ ์ƒ๊ด€๊ณ„์ˆ˜( R 2 )๋Š” 0.88์ด๋‹ค.

$$K_T=0.393\;\exp\left(\frac{R_C}d\right)+0.072\;\exp\left(\frac{R_C}{H_S}\right)+0.081\;\ln\left(\frac{H_S}{L_S}\right)-0.162\;\ln\left(\frac W{L_S}\right)-0.038$$ (3)

Fig. 13์€ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ๊ฒฝํ—˜์‹์— ์˜ํ•œ ๊ฒฐ๊ณผ๋ฅผ ๋น„๊ต ๋„์‹œํ•œ ๊ฒƒ์œผ๋กœ์„œ ์ƒ๋Œ€์ƒ๋‹จํญ( W / L S )์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ์‹คํ—˜๊ฒฐ๊ณผ๋ณด๋‹ค ์‚ฐ์ •์‹์— ์˜ํ•œ ๊ฒฐ๊ณผ๊ฐ€ ์•ฝ๊ฐ„ ํฐ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ์‚ฐ์ •๋จ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์ „์ˆ ํ•œ ๋ฐ”์™€ ๊ฐ™์ด ์ผ๋ฐ˜์ ์ธ ์„ค๊ณ„์กฐ๊ฑด ๋ฒ”์œ„๋‚ด์—์„œ๋Š” ์ ์šฉ๊ฐ€๋Šฅํ•˜๋‹ค๊ณ  ํŒ๋‹จ๋œ๋‹ค.

Figure_KSCE_40_05_05_F13.jpg
Fig. 13.

Wave Transmission Coefficients as a Function of the Relative Crest Width ( W / L S ) According to the Different Values of R C / d & R C / H S for D n =0.074 m. Open Circles Indicate Experimental Data. Solid and Dashed Lines Indicate the Results of the Empirical Formula [Eq. (3)]

Fig. 14๋Š” ๋ณธ ์—ฐ๊ตฌ์—์„œ ์ˆ˜ํ–‰ํ•œ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ์‚ฐ์ •์‹์— ์˜ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ๋น„๊ต ๋„์‹œํ•œ ๊ฒƒ์œผ๋กœ์„œ D n =0.042 m ์กฐ๊ฑด์ธ ๊ฒฝ์šฐ๋ณด๋‹ค๋Š” ๋ถ„์‚ฐ์ด ํฌ์ง€๋งŒ ๋น„๊ต์  ์ž˜ ์ผ์น˜ํ•˜๊ณ  ์žˆ์Œ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค.

Figure_KSCE_40_05_05_F14.jpg
Fig. 14.

Comparison between Measured Data and Empirical Formula [Eq. (3)] for D n =0.074 m

4.4 ํˆฌ๊ณผํ˜• ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •

ํ”ผ๋ณต์žฌ์˜ ๊ทœ๊ฒฉ์€ ์„ค๊ณ„ํŒŒ๊ณ ์— ๋”ฐ๋ผ ๊ฒฐ์ •๋˜๊ธฐ ๋•Œ๋ฌธ์— ๊ทธ ํฌ๊ธฐ๋Š” ์„œ๋กœ ๋‹ค๋ฅด๋ฉฐ, ๊ณต๊ทน์œจ์ด ์•ฝ 50 %์ธ Tetrapod์˜ ๊ฒฝ์šฐ์—๋„ ํ”ผ๋ณต์žฌ์˜ ํฌ๊ธฐ์— ๋”ฐ๋ฅธ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜์˜ ์ฐจ์ด๋Š” ๋ฐœ์ƒํ•  ์ˆ˜ ์žˆ๋‹ค. ๋”ฐ๋ผ์„œ ํ”ผ๋ณต์žฌ์˜ ๊ทœ๊ฒฉ์— ๋”ฐ๋ฅธ ๋ณ€ํ™”๋ฅผ ๊ฒ€ํ† ํ•˜๊ธฐ ์œ„ํ•ด ๋ณธ ์‹คํ—˜์—์„œ๋Š” ๊ณต์นญ๊ธธ์ด๊ฐ€ D n =0.042 m์™€ D n =0.074 m์ธ Tetrapod๋ฅผ ์ด์šฉํ•˜์—ฌ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ์‚ฐ์ •ํ•˜์˜€๋‹ค. ๊ฐ๊ฐ์˜ ๊ณต์นญ๊ธธ์ด์— ํ•ด๋‹นํ•˜๋Š” ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์‹์ธ Eqs. (2) and (3)์„ ์ด์šฉํ•˜์—ฌ ๊ฐ ๊ณต์นญ๊ธธ์ด์— ๋Œ€ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ๋น„๊ตํ•˜์˜€์œผ๋ฉฐ, ๊ทœ๊ฒฉ์ด ์ž‘์€ Tetrapod๋กœ ์ œ์ฒด๋ฅผ ํ˜•์„ฑํ•œ ๊ฒฝ์šฐ๊ฐ€ ๋ณด๋‹ค ๋‚ฎ์€ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ๋ณด์˜€๋‹ค(Fig. 15 ์ฐธ์กฐ). ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ƒ๋Œ€์ƒ๋‹จํญ์ด ์ž‘์€ ๊ฒฝ์šฐ๋ณด๋‹ค ํฐ ๊ฒฝ์šฐ์— ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜์˜ ์ฐจ์ด๊ฐ€ ํฌ๊ฒŒ ๋‚˜ํƒ€๋‚ฌ์œผ๋ฉฐ, ์ด๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์ œ์ฒด๋ฅผ ํ†ตํ•œ ํˆฌ๊ณผํŒŒ ์ฐจ์ด ๋•Œ๋ฌธ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

Figure_KSCE_40_05_05_F15.jpg
Fig. 15.

Wave Transmission Coefficients by Tetrapod Size for R C / H S =0.2

๋ณธ ์—ฐ๊ตฌ์—์„œ Tetrapod์˜ ํฌ๊ธฐ์— ๊ด€๊ณ„ ์—†๋Š” ์‚ฐ์ •์‹์˜ ๋„์ถœ์„ ์œ„ํ•ด ๊ณต์นญ๊ธธ์ด D n =0.042 m์™€ D n =0.074 m์ธ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ํ†ตํ•ฉํ•˜์—ฌ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์‹์„ ์ถ”๊ฐ€๋กœ ๋„์ถœํ•˜์˜€์œผ๋ฉฐ, ์‚ฐ์ •์‹์€ Eq. (4)์™€ ๊ฐ™๋‹ค. ์‹คํ—˜๊ฒฐ๊ณผ์™€ ํ†ตํ•ฉ๋œ ๊ฒฝํ—˜์‹๊ฐ„์˜ ์ƒ๊ด€๊ณ„์ˆ˜( R 2 )๋Š” R 2 =0.90์œผ๋กœ์„œ Eq. (2)๋ณด๋‹ค๋Š” ์ž‘๊ณ , Eq. (3)๋ณด๋‹ค๋Š” ํฌ๋‹ค.

$$K_T=0.380\;\exp\left(\frac{R_C}d\right)+0.095\;\exp\left(\frac{R_C}{H_S}\right)+0.072\;\ln\left(\frac{H_S}{L_S}\right)-0.188\;\ln\left(\frac W{L_S}\right)+0.013$$ (4)

๊ณต์นญ๊ธธ์ด D n =0.042 m์™€ D n =0.074 m์ธ ์‹คํ—˜๊ฒฐ๊ณผ๋กœ๋ถ€ํ„ฐ ๋„์ถœ๋œ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์‹ Eq. (4)๋ฅผ ์ด์šฉํ•˜์—ฌ D n =0.042 m์™€ D n =0.074 m์ธ ๊ฐ๊ฐ์˜ ์กฐ๊ฑด์— ํ•ด๋‹นํ•˜๋Š” ์‹คํ—˜๊ฒฐ๊ณผ์™€ ๋น„๊ตํ•˜์˜€๋‹ค. D n =0.042 m์™€ D n =0.074 m์˜ ์‹คํ—˜๊ฒฐ๊ณผ์™€ Eq. (4)๋ฅผ ๊ฐ๊ฐ ๋น„๊ต ๋„์‹œํ•œ ๊ฒƒ์ด Figs. 16 and 17์ด๋‹ค. D n =0.042 m์ธ ๊ฒฝ์šฐ์—๋Š” ์‚ฐ์ •์‹์— ์˜ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ์‹คํ—˜๊ฒฐ๊ณผ๋ณด๋‹ค ๋‹ค์†Œ ํฌ๊ฒŒ, D n =0.074 m์ธ ๊ฒฝ์šฐ์—๋Š” ์‚ฐ์ •์‹์— ์˜ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ์‹คํ—˜๊ฒฐ๊ณผ๋ณด๋‹ค ๋‹ค์†Œ ์ž‘๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด๋Š” Fig. 15์— ๋„์‹œํ•œ ๋ฐ”์™€ ๊ฐ™์ด ํ”ผ๋ณต์žฌ์˜ ๊ทœ๊ฒฉ์— ๋”ฐ๋ผ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜์˜ ์ฐจ์ด๊ฐ€ ๋ฐœ์ƒํ•˜์ง€๋งŒ, ์ „์ฒด ์‹คํ—˜์ž๋ฃŒ๋ฅผ ํ†ตํ•ฉํ•˜์—ฌ ์‚ฐ์ •์‹์„ ๋„์ถœํ•จ์œผ๋กœ ์ธํ•ด ๋ฐœ์ƒ๋˜๋Š” ํ˜„์ƒ์ด๋‹ค.

Figure_KSCE_40_05_05_F16.jpg
Fig. 16.

Comparison between Measured Data and Empirical Formula [Eq. (4)] for D n =0.042 m

Figure_KSCE_40_05_05_F17.jpg
Fig. 17.

Comparison between Measured Data and Empirical Formula [Eq. (4)] for D n =0.074 m

Fig. 18์€ ๋ณธ ์—ฐ๊ตฌ์—์„œ ์ˆ˜ํ–‰ํ•œ ์ „์ฒด ์‹คํ—˜๊ฒฐ๊ณผ์™€ Eq. (4)์— ์˜ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ๋น„๊ต ๋„์‹œํ•œ ๊ฒƒ์ด๋‹ค. ๊ฐ๊ฐ์˜ ๊ณต์นญ๊ธธ์ด์— ํ•ด๋‹นํ•˜๋Š” ์‹คํ—˜๊ฒฐ๊ณผ์™€ ์‚ฐ์ •์‹์„ ๋น„๊ตํ•œ Fig. 11 ๋ฐ Fig. 14๋ณด๋‹ค๋Š” ์ผ์น˜์„ฑ์ด ๋‹ค์†Œ ๋–จ์–ด์ง€์ง€๋งŒ, ์‹ค๋ฌด์— ์ ์šฉํ•˜๊ธฐ์—๋Š” ๋ฌด๋ฆฌ๊ฐ€ ์—†์„ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

Figure_KSCE_40_05_05_F18.jpg
Fig. 18.

Comparison between Measured Data and Empirical Formula [Eq. (4)]

2.1์ ˆ์— ๊ธฐ์ˆ ํ•œ ๊ธฐ์กด ์„ค๊ณ„์‚ฌ๋ก€ ์กฐ๊ฑด์„ ๋Œ€์ƒ์œผ๋กœ ๋ณธ ์—ฐ๊ตฌ์—์„œ ์ œ์•ˆํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์‹ Eq. (4)์™€ Takayama et al.(1985)์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์‹ Eq. (1)์„ ์ ์šฉํ•˜์—ฌ ๊ฒฐ๊ณผ๋ฅผ ๋น„๊ตํ•œ ๊ฒƒ์ด Fig. 19์ด๋‹ค. ์กฐ๊ฑด์— ๋”ฐ๋ผ ๋ณธ ์—ฐ๊ตฌ์˜ ๊ฒฐ๊ณผ๊ฐ€ Takayama et al.(1985)์˜ ๊ฒฐ๊ณผ๋ณด๋‹ค ์•ฝ๊ฐ„ ํฐ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ์‚ฐ์ •๋˜์ง€๋งŒ, ์ „์ฒด์ ์œผ๋กœ ์œ ์‚ฌํ•˜๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

Figure_KSCE_40_05_05_F19.jpg
Fig. 19.

Comparison between This Study and Takayama et al. (1985) Results

5. ๊ฒฐ ๋ก 

๊ตญ๋‚ด์—์„œ๋Š” ์—ฐ์•ˆ์นจ์‹ ์ €๊ฐ์„ ์œ„ํ•œ ๋Œ€์ฑ…์œผ๋กœ์„œ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ(์ž ์ œ, ์ธ๊ณต๋ฆฌํ”„)์„ ๋Œ€๋ถ€๋ถ„ ์ ์šฉํ•˜๊ณ  ์žˆ์œผ๋ฉฐ, ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ํ”ผ๋ณต์žฌ๋กœ๋Š” Tetrapod๊ฐ€ ์ฃผ๋กœ ์‚ฌ์šฉ๋˜๊ณ  ์žˆ๋‹ค. ๊ทธ๋ฆฌ๊ณ  ๋ชฉํ‘œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜์— ๋”ฐ๋ผ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ๊ธฐํ•˜ํ•™์  ์ œ์›(์ƒ๋‹จ์—ฌ์œ ๊ณ , ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ํญ ๋“ฑ)์ด ๊ฒฐ์ •๋˜๋Š” ๊ฒƒ์ด ์ผ๋ฐ˜์ ์ด๋‹ค. ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” Tetrapod๋กœ ์ œ์ฒด๋ฅผ ํ˜•์„ฑํ•œ ํˆฌ๊ณผํ˜• ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์„ ๋Œ€์ƒ์œผ๋กœ ์ƒ๋Œ€์—ฌ์œ ์ˆ˜์‹ฌ, ์ƒ๋‹จ์—ฌ์œ ๊ณ , ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ƒ๋‹จํญ, ์œ ์˜ํŒŒ๊ณ  ๋ฐ ์œ ์˜์ฃผ๊ธฐ ๋“ฑ์„ ๋ณ€ํ™”์‹œํ‚ค๋ฉด์„œ ์ „๋‹ฌํŒŒ๊ณ  ์‚ฐ์ •์„ ์œ„ํ•œ 2์ฐจ์› ์ˆ˜๋ฆฌ๋ชจํ˜•์‹คํ—˜์„ ์‹ค์‹œํ•˜์˜€๋‹ค. ์ด๋Ÿฌํ•œ 2์ฐจ์› ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ์ด์šฉํ•˜์—ฌ ํˆฌ๊ณผํ˜• ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ์‚ฐ์ •ํ•  ์ˆ˜ ์žˆ๋Š” ๊ฒฝํ—˜์‹์„ ์ œ์•ˆํ•˜์˜€๋‹ค.

(1)ํŒŒํ˜•๊ฒฝ์‚ฌ๊ฐ€ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋Š” ์ฆ๊ฐ€ํ•จ์„ ์•Œ ์ˆ˜ ์žˆ์—ˆ์œผ๋ฉฐ, ์ด๋Š” Takayama et al.(1985)์˜ ๊ฒฐ๊ณผ์™€ ์ผ์น˜ํ•œ๋‹ค.

(2)๋™์ผํ•œ ๊ณต๊ทน์œจ์„ ๊ฐ€์ง€๋Š” ๊ฐ™์€ ํ”ผ๋ณต์žฌ์˜ ๊ฒฝ์šฐ์—๋„ ํ”ผ๋ณต์žฌ์˜ ๊ทœ๋ชจ๊ฐ€ ์ƒ๋Œ€์ ์œผ๋กœ ์ž‘์„ ๋•Œ ๋” ์ž‘์€ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๊ฐ€ ๊ณ„์ธก๋˜์—ˆ์œผ๋ฉฐ, ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ƒ๋‹จํญ์ด ๋„“์„์ˆ˜๋ก ๋ช…ํ™•ํ•œ ์ฐจ์ด๋ฅผ ๋ณด์˜€๋‹ค. ์ด๋Š” ๋™์ผ ํ”ผ๋ณต์žฌ์ด๊ณ  ๋™์ผํ•œ ๊ณต๊ทน์œจ์ธ ๊ฒฝ์šฐ์—๋„ ํˆฌ๊ณผ์œจ์˜ ์ฐจ์ด์— ๊ธฐ์ธํ•˜๋Š” ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

(3)๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” 2๊ฐ€์ง€ ๊ทœ๊ฒฉ์˜ Tetrapod๋ฅผ ์ ์šฉํ•˜์—ฌ ์ „๋‹ฌํŒŒ๊ณ  ์‚ฐ์ •์„ ์œ„ํ•œ 2์ฐจ์› ์ˆ˜๋ฆฌ์‹คํ—˜์„ ์‹ค์‹œํ•˜์˜€๋‹ค. 2๊ฐ€์ง€ ๊ทœ๊ฒฉ์˜ Tetrapod ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ํ†ตํ•ฉํ•˜์—ฌ ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ ์„ค์น˜์œ„์น˜์—์„œ์˜ ์ƒ๋Œ€์—ฌ์œ ์ˆ˜์‹ฌ( R C / d ), ์ƒ๋Œ€์—ฌ์œ ๊ณ ( R C / H S ), ํŒŒํ˜•๊ฒฝ์‚ฌ( H S / L S ) ๋ฐ ์ƒ๋Œ€์ƒ๋‹จํญ( W / L S )์„ ๋ฌด์ฐจ์› ๋ณ€์ˆ˜๋กœ ํ•œ ๋‹ค์ค‘ํšŒ๊ท€๋ถ„์„์„ ์‹ค์‹œํ•˜๊ณ  ๋‹ค์Œ๊ณผ ๊ฐ™์€ ํˆฌ๊ณผํ˜• ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜( K T ) ์‚ฐ์ •์‹์„ ์ œ์•ˆํ•˜์˜€๋‹ค.

K T = 0 . 380   exp R C d + 0 . 095   exp R C H S + 0 . 072   ln H S L S - 0 . 188   ln W L S + 0 . 013 ์ƒ๊ธฐ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์‹์˜ ๋„์ถœ์— ์‚ฌ์šฉ๋œ ๊ฐ ๋ฌด์ฐจ์›๋ณ€์ˆ˜๋“ค์˜ ์ ์šฉ๋ฒ”์œ„๋Š” 0.1โ‰ค R C / d โ‰ค0.2, 0.2โ‰ค R C / H S โ‰ค1.0, 0.01โ‰ค H S / L S โ‰ค0.06, 0.04โ‰ค W / L S โ‰ค1.5์ด๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์ „๋ฐ˜์ ์ธ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ๋ถ„ํฌ ๊ฒฝํ–ฅ์„ ๊ฒ€ํ† ํ•ด๋ณธ ๊ฒฐ๊ณผ, ์ƒ๊ธฐ ์‚ฐ์ •์‹์˜ ์ ์šฉ๋ฒ”์œ„๋ฅผ ํฌ๊ฒŒ ๋ฒ—์–ด๋‚˜์ง€ ์•Š๋Š” ์กฐ๊ฑด์—์„œ๋Š” ์ ์šฉ์ด ๊ฐ€๋Šฅํ•  ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

(4)๊ธฐ์กด ์„ค๊ณ„์‚ฌ๋ก€๋ฅผ ๋Œ€์ƒ์œผ๋กœ ๋ณธ ์—ฐ๊ตฌ์—์„œ ๋„์ถœ๋œ ์‚ฐ์ •์‹๊ณผ Takayama et al.(1985)์˜ ์‚ฐ์ •์‹์„ ์ด์šฉํ•˜์—ฌ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜๋ฅผ ๋น„๊ตํ•˜์˜€์œผ๋ฉฐ, ๋‘ ์‚ฐ์ •์‹์— ์˜ํ•œ ๊ฒฐ๊ณผ๋Š” ๋น„๊ต์  ์ž˜ ์ผ์น˜ํ•˜์˜€๋‹ค.

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์˜ ์ œ์ฒด๊ฐ€ Tetrapod๋กœ ๊ตฌ์„ฑ๋œ ํˆฌ๊ณผํ˜• ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์— ๋Œ€ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์‹์„ ์ œ์•ˆํ•˜์˜€์œผ๋ฉฐ, ์ถ”ํ›„ ๊ฒฝ์‚ฌํ˜•(ํ”ผ๋ณต์žฌ ๋‚ด์ธก์— ์‚ฌ์„์ด ์„ค์น˜๋œ ๊ฒฝ์šฐ)๊ณผ ๋ถˆํˆฌ๊ณผํ˜• ์ˆ˜์ค‘๊ตฌ์กฐ๋ฌผ์— ๋Œ€ํ•œ ํŒŒ๊ณ ์ „๋‹ฌ๊ณ„์ˆ˜ ์‚ฐ์ •์‹์„ ์ œ์•ˆํ•˜๊ณ ์ž ํ•œ๋‹ค.

Acknowledgements

๋ณธ ๋…ผ๋ฌธ์€ ํ•ด์–‘์ˆ˜์‚ฐ๋ถ€ ๋ฐ ํ•ด์–‘์ˆ˜์‚ฐ๊ณผํ•™๊ธฐ์ˆ ์ง„ํฅ์›์˜ ์—ฐ๊ตฌ๋น„ ์ง€์›(๊ณผ์ œ๋ฒˆํ˜ธ: 20180323) ๋ฐ ๊ตญํ† ๊ตํ†ต๋ถ€ ๊ตญํ† ๊ตํ†ต๊ธฐ์ˆ ์ด‰์ง„์—ฐ๊ตฌ์‚ฌ์—…์˜ ์—ฐ๊ตฌ๋น„ ์ง€์›(18-CTAP-B139288-02)์œผ๋กœ ์ˆ˜ํ–‰๋œ ์—ฐ๊ตฌ์ด๋ฉฐ, ์—ฐ๊ตฌ๋น„ ์ง€์›์— ๊ฐ์‚ฌ๋“œ๋ฆฝ๋‹ˆ๋‹ค.

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