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  1. ์ธ๋•๋Œ€ํ•™๊ต ๊ฑด์„ค์ •๋ณด๊ณตํ•™๊ณผ ๊ต์ˆ˜ (Professor, Department of Construction Information Engineering, Induk Univesity, Seoul 01878, Rep. of Korea)
  2. ์„œ์šธ๋Œ€ํ•™๊ต ๊ฑด์ถ•ํ•™๊ณผ ๊ต์ˆ˜ (Professor, Department of Architecture & Architectural Engineering, Seoul National University, Seoul 08826, Rep. of Korea)
  3. ์„œ์šธ๋Œ€ํ•™๊ต ๊ฑด์ถ•ํ•™๊ณผ ๋ฐ•์‚ฌ๊ณผ์ • (Graduate Student, Department of Architecture & Architectural Engineering, Seoul National University, Seoul 08826, Rep. of Korea)



๊ฐ•์—ฐ์„  ๋ถ€์‹, ๊ทธ๋ผ์šฐํŒ…, ๊ทธ๋ฆฌ์Šค, HDPE ๋„๋ง‰, ๋ถ€์‹ ์ „๋ฅ˜๋ฐ€๋„
strand corrosion, grouting, grease, HDPE, corrosion current density

1. ์„œ ๋ก 

ํ”„๋ฆฌ์ŠคํŠธ๋ ˆ์ŠคํŠธ ์ฝ˜ํฌ๋ฆฌํŠธ๋Š” ์ธ์žฅ๊ฐ•๋„ 1,860~2,360 MPa์˜ ๊ณ ์žฅ๋ ฅ ๊ฐ•์œผ๋กœ ๋œ ๊ฐ•์—ฐ์„ , ๋˜๋Š” ์ธ์žฅ๊ฐ•๋„ 1,000~1,400 MPa์˜ ๊ณ ์žฅ๋ ฅ ๊ฐ•๋ด‰์ด ์‚ฌ์šฉ๋˜๋ฉฐ, ํ”„๋ฆฌ์ŠคํŠธ๋ ˆ์ŠคํŠธ ๊ฐ•์žฌ๋Š” ๊ทธ ์ธ์žฅ ๊ฐ•๋„์˜ 60~80 %์— ํ•ด๋‹นํ•˜๋Š” ์‘๋ ฅ์œผ๋กœ ์ƒ์‹œ ์ธ์žฅ ์ƒํƒœ์— ๋†“์ด๊ฒŒ ๋œ๋‹ค. ํ”„๋ฆฌ์ŠคํŠธ๋ ˆ์ŠคํŠธ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ๋Š” ๊ท ์—ด์ด ๋ฐœ์ƒํ•˜์ง€ ์•Š์œผ๋ฉฐ, ๊ท ์—ด์ด ๋ฐœ์ƒํ•˜๋”๋ผ๋„ ํ•˜์ค‘์ด ์—†์–ด์ง€๋ฉด ์ฆ‰๊ฐ์ ์œผ๋กœ ์•„๋ฌผ๊ฒŒ ๋˜๋Š” ํŠน์„ฑ์ด ์žˆ์œผ๋ฏ€๋กœ, ๋ถ€์‹์— ๋Œ€ํ•œ ์—ผ๋ ค๋Š” ์ฒ ๊ทผ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ๋ณด๋‹ค ๋œํ•˜๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ๊ฐ•์—ฐ์„ ์ด ๋ถ€์‹๋œ ํ”„๋ฆฌ์ŠคํŠธ๋ ˆ์ŠคํŠธ ๊ตฌ์กฐ์ฒด๋Š” ๊ทนํ•œํ•˜์ค‘์— ๋„๋‹ฌํ•˜๊ธฐ ์ „์— ๊ฐ•์—ฐ์„ ๋“ค์˜ ์กฐ๊ธฐ ํŒŒ๋‹จ์— ์˜ํ•ด ํœจ๊ฐ•๋„๊ฐ€ ๊ธ‰๊ฒฉํžˆ ๊ฐ์†Œ๋  ์ˆ˜ ์žˆ๋‹ค.

์ผ๋ฐ˜์ ์œผ๋กœ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ์ฒด๋Š” ์ฒ ๊ทผ์˜ ๋ถ€์‹ ์œ ๋ฌด์— ๋”ฐ๋ผ ๊ตฌ์กฐ๋ฌผ์˜ ์ˆ˜๋ช…๋‹จ๊ณ„๋ฅผ ์ฒ ๊ทผ์˜ ๋ถ€์‹์ด ์‹œ์ž‘๋˜๊ธฐ ์ „๊นŒ์ง€์˜ ์ž ๋ณต๊ธฐ๊ฐ„๊ณผ ๋ถ€์‹ ์ดํ›„์˜ ์ง„์ „๊ธฐ ๋“ฑ, 2๋‹จ๊ณ„๋กœ ๋‚˜๋ˆŒ ์ˆ˜ ์žˆ๋‹ค(Tuutti 1979). ๊ทธ๋Ÿฌ๋‚˜ ํ”„๋ฆฌ์ŠคํŠธ๋ ˆ์ŠคํŠธ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ์ฒด๋Š” Fig.1๊ณผ ๊ฐ™์ด ์‘๋ ฅ๋ถ€์‹ ๊ท ์—ด์— ์˜ํ•œ ๊ฐ•์—ฐ์„ ์˜ ํŒŒ๊ดด๋ฅผ ํ† ๋Œ€๋กœ (i) ๊ท ์—ด์‹œ์ž‘ ์‹œ๊ธฐ, (ii) ๋Š๋ฆฐ ๊ท ์—ด ์ง„์ „๊ธฐ, (iii) ์ž„๊ณ„์ƒํƒœ๊นŒ์ง€ ๋น ๋ฅด๊ฒŒ ์ง„ํ–‰๋˜์–ด ๊ฐ‘์ž‘์Šค๋Ÿฌ์šด ์ทจ์„ฑํŒŒ๊ดด์— ๋„๋‹ฌํ•˜๋Š” ๊ธ‰์† ์ง„์ „๊ธฐ์˜ 3๋‹จ๊ณ„๋กœ ๊ตฌ๋ถ„๋œ๋‹ค(Brown 1968). ์ด๋Š” ์กฐ์ง์ด ์ทจ์•ฝํ•ด์ง€๋Š” ์‘๋ ฅ ๋ถ€์‹(stress corrosion) ํ˜„์ƒ ๋ฐ ์ˆ˜์†Œ ์ทจํ™”(hydrogen embrittlement)๊ฐ€ ์ฃผ์š” ์›์ธ์œผ๋กœ์„œ, ๊ฐ•์—ฐ์„ ์˜ ๊ฐ•๋„๊ฐ€ ๋†’์„์ˆ˜๋ก ๋”์šฑ ์ทจ์•ฝํ•˜๋‹ค(Fricker and Vogel 2006; Mathy et al. 1996; Revie and Uhlig 1985). ๋ถ€์‹๊ณตํ•™์—์„œ ์‘๋ ฅ ๋ถ€์‹์€ ๋ถ€์‹ํ™˜๊ฒฝ, ๊ธˆ์†์˜ ์˜ˆ๋ฏผ์„ฑ, ์ธ์žฅ์‘๋ ฅ์˜ 3๊ฐ€์ง€ ์กฐ๊ฑด์ด ๋งŒ์กฑ๋˜์—ˆ์„ ๋•Œ ๋ฐœ์ƒํ•˜๋Š” ๊ฒƒ์œผ๋กœ ์•Œ๋ ค์ ธ ์žˆ์œผ๋‚˜, ๋•Œ๋กœ๋Š” ๊ตฌ์กฐ์ฒด์˜ ์ข…๋ฅ˜์— ๋”ฐ๋ผ ์‹œ๊ฐ„๊ณผ ์‚ฌ์šฉ์กฐ๊ฑด์ด ์„œ๋กœ ๊ฒฐํ•ฉํ•˜์—ฌ ์˜ˆ์™ธ์  ์†์ƒ์„ ์ดˆ๋ž˜ํ•  ์ˆ˜ ์žˆ๋‹ค(Jones 1995). ๋Œ€ํ‘œ์ ์ธ ์˜ˆ๊ฐ€ ํ”„๋ฆฌ์ŠคํŠธ๋ ˆ์ŠคํŠธ ๊ฐ•์—ฐ์„ ์ด๋‹ค. ๊ฐ•์—ฐ์„  ํ‘œ๋ฉด์˜ ๊ณต์‹(pit) ์„ ๋‹จ(tip)์€ Fig.2์™€ ๊ฐ™์ด ํ™œ์„ฑํ™”๋œ ์–‘๊ทน์ฒ˜๋Ÿผ ๋ถ„ํ•ด์ž‘์šฉ์ด ๋ฐœ์ƒํ•˜๋Š”๋ฐ, ๊ณต์‹ ์„ ๋‹จ์˜ ๋†’์€ ์‘๋ ฅ์œผ๋กœ ์†Œ์„ฑ๋ณ€ํ˜•์ด ์œ ๋ฐœํ•œ๋‹ค. ๊ณต์‹ ์„ ๋‹จ์€ ์–‘๊ทน์œผ๋กœ ์กด์†๋˜๊ณ  ๋ถ„ํ•ด์ž‘์šฉ์€ ๋น ๋ฅธ ์†๋„๋กœ ์ง€์†ํ•˜์—ฌ ๊ถ๊ทน์ ์œผ๋กœ ์‘๋ ฅ๊ณผ ๋น ๋ฅธ ๋ถ€์‹์˜ ์กฐํ•ฉ์ด ๊ท ์—ด์„ ์œ ๋ฐœํ•˜๊ณ  ๊ฑฐ์‹œ์ ์œผ๋กœ ์‹œ๊ฐ์  ๊ฒฝ๊ณ  ์—†์ด ๊ตฌ์กฐ์ฒด์˜ ๊ธ‰์ž‘์Šค๋Ÿฌ์šด ์ทจ์„ฑํŒŒ๊ดด๋กœ ์—ฐ๊ณ„๋œ๋‹ค. ์ด ๊ณผ์ •์€ Fig.1์˜ 3๋ฒˆ์งธ ๋‹จ๊ณ„๋กœ์„œ ๊ทธ๋ฆผ์ฒ˜๋Ÿผ ๋งค์šฐ ๊ธ‰์†ํžˆ ์ง„์ „๋˜๊ธฐ ๋•Œ๋ฌธ์— ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ๋ณด๋‹ค ๊ณ„ํš ๋ฐ ์„ค๊ณ„ ๋‹จ๊ณ„์—์„œ๋ถ€ํ„ฐ ๋ถ€์‹์— ๋Œ€ํ•œ ๋”์šฑ ์„ธ์‹ฌํ•œ ์ฃผ์˜๊ฐ€ ์š”๊ตฌ๋œ๋‹ค.

Fig. 1. Process of phenomena that lead to the initiation and propagation of hydrogen-induced cracking and eventual failure of A and B having different fracture toughness (dcr=critical flaw size, ti=initiation time, tr=time of failure)

../../Resources/kci/JKCI.2019.31.6.557/fig1.png

Fig. 2. Schematic description of corrosion process taking place at tip of pit or crack in a stressed strand leading to its embrittlement, (a) stress corrosion cracking, (b) hydrogen embrittlement (Bentur et al. 1997)

../../Resources/kci/JKCI.2019.31.6.557/fig2.png

ํ•œํŽธ, ๊ตฌ์กฐ์ฒด ๋‚ด ๊ฐ•์—ฐ์„ ์€ ๋ถ€์ฐฉ์œ ๋ฌด์— ๋”ฐ๋ผ ๊ฐ•์—ฐ์„ ๊ณผ ๋•ํŠธ ์‚ฌ์ด์˜ ๊ณต๊ฐ„์„ ๊ทธ๋ผ์šฐํŒ…์œผ๋กœ ์ฑ„์šฐ๋Š” ๋ถ€์ฐฉ๊ณ„์™€ ๊ทธ๋ฆฌ์Šค๋‚˜ ์™์Šค๋กœ ์ฑ„์šฐ๋Š” ๋น„๋ถ€์ฐฉ๊ณ„ ๋“ฑ, 2๊ฐ€์ง€๋กœ ๋Œ€๋ณ„๋œ๋‹ค. ๋ถ€์ฐฉ๊ณ„ ๊ฐ•์—ฐ์„ ์€ ๊ณ ์•Œ์นผ๋ฆฌ ํ™˜๊ฒฝ์„ ์กฐ์„ฑํ•˜์—ฌ ๊ฐ•์—ฐ์„  ํ‘œ๋ฉด์— ๊ฐ•๋ ฅํ•œ ๋‚ด์‹์„ฑ ์‚ฐํ™”ํ”ผ๋ง‰์„ ํ˜•์„ฑํ•˜๋Š” ๋ฐฉ์‹์˜ ๋งˆ์ง€๋ง‰ ๋ฐฉํ˜ธ๋ง‰์ด์ง€๋งŒ, ๋ฌผ๊ณผ ์‚ฐ์†Œ์— ๋…ธ์ถœ๋œ ๊ทธ๋ผ์šฐํŒ… ๋‚ด ์—ผ์†Œ์ด์˜จ ๋˜๋Š” ํƒ„์‚ฐํ™”๋กœ ์ธํ•˜์—ฌ ๋ถ€์‹์ด ์‹œ์ž‘๋  ์ˆ˜ ์žˆ๋‹ค. ์ผ๋‹จ, ๋ถ€์‹์ด ์‹œ์ž‘๋˜๋ฉด ๋ถ€์‹์†๋„๋Š” ์‚ฐ์†Œ์˜ ์œ ์ž…์†๋„, ์ˆ˜๋ถ„๋Ÿ‰, ์ „๊ธฐ์ €ํ•ญ์„ฑ, ๊ทธ๋ผ์šฐํŒ…์˜ pH, ์—ผ์†Œ๋†๋„ ๋“ฑ๊ณผ ๊ฐ™์€ ๋‹ค์–‘ํ•œ ์š”์ธ์— ์˜์กด๋œ๋‹ค(FHWA 2014). ํŠนํžˆ, ๊ฐ•์—ฐ์„ ์„ ์กฐ๊ธฐ์— ๋ถ€์‹์‹œํ‚ค๋Š” ์ฃผ์š” ์š”์ธ์€ ์—ผ์†Œ์ด์˜จ ๋˜๋Š” ํ™ฉ์‚ฐ์ด์˜จ, ๋ฏธ์„ธ๊ท ์—ด, ๋ถˆ์ถฉ์ „๋œ ๊ณต๊ทน, ์‚ฐ์†Œ์™€ ์Šต๋„ ๋“ฑ์ด๋‹ค(FHWA 2012; Trejo et al. 2009). ์ตœ๊ทผ, ์„œ์šธ์‹œ ์ •๋ฆ‰์ฒœ ๊ณ ๊ฐ€์˜ ๊ฒฝ์šฐ๋Š”, ํด๋ฆฌ์—ํ‹ธ๋ Œ ๊ด€ ๋‚ด๋ถ€ ๊ฐ•์—ฐ์„  ๋ถ€์‹์„ ๋ฐฉ์ง€ํ•˜๊ธฐ ์œ„ํ•ด ์ฑ„์›Œ ๋„ฃ๋Š” ๊ทธ๋ผ์šฐํŒ… ์ถฉ์ „์ด ๋ถˆ์ถฉ๋ถ„ํ•œ ์ƒํƒœ์—์„œ ๊ทธ๋ผ์šฐํŒ…์˜ ๋ฌผ ๋น„์œจ์ด ๋†’์•„ ๋ธ”๋ฆฌ๋”ฉ์ด ๋ฐœ์ƒํ•˜์˜€๊ณ , ๊ทธ๋ผ์šฐํŒ… ํ›„ ์—์–ด๋ฒคํŠธ(๊ณต๊ธฐ๊ตฌ๋ฉ)๊ฐ€ ์ œ๋Œ€๋กœ ๋ฐ€๋ด‰๋˜์ง€ ์•Š์•„ ์—ผ์†Œ์ด์˜จ์„ ํ•จ์œ ํ•œ ๋…ธ๋ฉด์ˆ˜๊ฐ€ ์นจํˆฌํ•˜์—ฌ ๋ถ€์‹๋˜์—ˆ๋‹ค(Jeon 2016). ์ตœ๊ทผ์˜ ์—ฐ๊ตฌ๋Š” ๋ถˆ์ถฉ๋ถ„ํ•˜๊ฒŒ ์ถฉ์ „๋œ ๊ทธ๋ผ์šฐํŒ…์—์„œ ์‹œ๋ฉ˜ํŠธ ์ค‘๋Ÿ‰๋Œ€๋น„ 0.4 %, ์ถฉ์ „์ด ์ž˜๋œ ๊ฒฝ์šฐ์—๋Š” 0.6 %์˜ ์—ผ์†Œ๋†๋„์—์„œ ๊ฐ๊ฐ ๋ถ€์‹์ด ์‹œ์ž‘๋˜๋ฉฐ, ๊ทธ๋ผ์šฐํŒ… ์ถฉ์ „ ํ’ˆ์งˆ๊ณผ ๋ฌด๊ด€ํ•˜๊ฒŒ 0.8 %์˜ ์—ผ์†Œ๋†๋„์—์„œ ๋ถ€์‹์ง„์ „์ด ์ง„ํ–‰๋˜๋Š” ๊ฒƒ์œผ๋กœ ๋ณด๊ณ ๋œ ๋ฐ” ์žˆ๋‹ค(FHWA 2014). ๊ทธ๋Ÿฌ๋‚˜ ์‹œ๋ฉ˜ํŠธ ์ค‘๋Ÿ‰๋Œ€๋น„ 0.4 %๋Š” ์ผ๋ฐ˜ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ์—์„œ ๋ณดํŽธ์ ์œผ๋กœ ๊ฐ„์ฃผ๋˜๋Š” ์ž„๊ณ„ ์—ผ์†Œ์ด์˜จ์–‘์œผ๋กœ์„œ, ๊ณ ์ธ์žฅ ์‘๋ ฅ์ด ์ƒ์‹œ ์ธ๊ฐ€๋˜๋Š” ๊ฐ•์—ฐ์„ ์€ ์ด๋ณด๋‹ค ๋” ๋‚ฎ์€ ์—ผ์†Œ์ด์˜จ์–‘์—๋„ ๋ถ€์‹๋  ๊ฒƒ์ž„์— ํ‹€๋ฆผ์—†๋‹ค(Rafols 2012). ๋”ฐ๋ผ์„œ, ํ”„๋ฆฌ์ŠคํŠธ๋ ˆ์ŠคํŠธ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ์ฒด์—์„œ๋Š” ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹ ๋ฐฉ์ง€๋Š” ๋‚ด๊ตฌ์„ฑ ํ–ฅ์ƒ์˜ ํ•ต์‹ฌ์ ์ธ ๊ธฐ์ˆ ์ด๋ฉฐ, ๋†’์€ ์‘๋ ฅ์ด ์ธ๊ฐ€๋œ ๊ฐ•์—ฐ์„ ์€ ๋”์šฑ ๋ถ€์‹์— ์ทจ์•ฝํ•˜๋ฏ€๋กœ, ํšจ๊ณผ์ ์ธ ๋ถ€์‹ ์ œ์–ด ๊ณต๋ฒ•์˜ ์„ ์ • ๋ฐ ๊ฐœ๋ฐœ์€ ๋Œ€๋‹จํžˆ ์ค‘์š”ํ•˜๋‹ค.

๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹์„ ์ œ์–ดํ•  ์ˆ˜ ์žˆ๋Š” ๋Œ€ํ‘œ์  ๋ฐฉ๋ฒ•์œผ๋กœ a) ์—ํญ์‹œ ๋„๋ง‰๋œ ๊ฐ•์—ฐ์„ , ๊ฐˆ๋ฐ”๋‚˜์ด์ฆˆ๋œ ๊ฐ•์—ฐ์„ , FRP ๋ณตํ•ฉ ๊ฐ•์—ฐ์„  ๋“ฑ๊ณผ ๊ฐ™์ด ๋‚ด์‹์„ฑ๋Šฅ์ด ํ–ฅ์ƒ๋œ ๋Œ€์ฒด์žฌ, b) ๋ถ€์‹์ด ์•ˆ ๋  ๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ๋ถˆ์นจํˆฌ์„ฑ ํ™˜๊ฒฝ์„ ์ œ๊ณตํ•˜๋Š” ๊ณ ๋ฐ€๋„ ๊ณ ๋ถ„์ž ๊ณ„์—ด ๋•ํŠธ์˜ ์‚ฌ์šฉ, c) ๊ณ ์„ฑ๋Šฅ ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ… ๋“ฑ์œผ๋กœ ์‰ฌ์Šค์™€์˜ ๊ณต๊ฐ„์„ ์ฑ„์šฐ๊ฑฐ๋‚˜, d) ์™์Šค ๋˜๋Š” ๊ทธ๋ฆฌ์Šค ๋“ฑ์˜ ์œ ์„ฑ๋ฌผ์งˆ์„ ๋„๋ง‰ํ•˜์—ฌ ์œ ํ•ด๋ฌผ์งˆ์„ ์ฐจ๋‹จํ•˜๋Š” ๊ณต๋ฒ• ๋“ฑ์ด ์žˆ๋‹ค(ACI Committee 222 2014). ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹์„ ์ œ์–ดํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ์„ค๊ณ„ ๋ฐ ์‹œ๊ณต๋‹จ๊ณ„์—์„œ ๋ถ€์ฐฉ์‹ ๊ทธ๋ผ์šฐํŒ…์„ ํ•˜๋Š” ๊ฒƒ์ด ๋ณดํŽธ์ ์ธ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ฐ„์ฃผ๋œ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ๋ถ€์žฌ ์ „๋‹จ๋ฉด์— ๊ฑธ์ณ ๋•ํŠธ ๋‚ด๋ถ€๋ฅผ ๊ท ์งˆํ•˜๊ฒŒ ๊ทธ๋ผ์šฐํŒ…ํ•˜๋Š” ๊ฒƒ์ด ์–ด๋ ค์šธ๋ฟ๋”๋Ÿฌ, ๊ทธ๋ผ์šฐํŒ… ์ž์ฒด์— ๋ฏธ์„ธ๊ท ์—ด์ด๋ผ๋„ ์กด์žฌํ•  ์ˆ˜ ์žˆ๊ณ , ๋”์šฑ์ด ๊ฐ•์—ฐ ์‹ฌ์„ ๊ณผ ์ธก์„  ๊ฐ„ ์‚ฌ์ด์˜ ๊ณต๊ฐ„์— ๊ณผ๋‹คํ•œ ๋ธ”๋ฆฌ๋”ฉ ์ˆ˜๊ฐ€ ์œ ์ž…๋˜๋Š” ์‹ฌ์ง€ํšจ๊ณผ ๋ฐ ์™ธ๋ถ€์—์„œ ์—ผ์†Œ์ด์˜จ์ด๋‚˜ ์ˆ˜๋ถ„๊ณผ ๊ฐ™์€ ์œ ํ•ด๋ฌผ์งˆ์ด ๊ฐ•์—ฐ์„ ๊ฐ„ ์ž”์—ฌ๊ณต๊ฐ„์„ ๋”ฐ๋ผ ๊ฐ•์žฌ ์ „์ฒด์— ๋ถ€์‹์„ ์œ ๋ฐœํ•  ์ˆ˜ ์žˆ๋‹ค(Permeh et al. 2016; Salas et al. 2004).

๊ทธ๋ž˜์„œ ๋ณธ ์—ฐ๊ตฌ๋Š” ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹๋ณดํ˜ธ๋ฅผ ์œ„ํ•œ ๋ถ€์ฐฉ์‹ ๋ฐ ๋น„๋ถ€์ฐฉ์‹ ๋ฐฉ๋ฒ• ๋“ค์„ ์—„์„ ํ•˜์—ฌ ๊ฐ•์—ฐ์„ ์— ๋Œ€ํ•œ ๋ฐฉ์‹ ํšจ๊ณผ๋ฅผ ๊ทœ๋ช…ํ•˜๊ณ ์ž ํ•œ๋‹ค. ๋ณธ ์—ฐ๊ตฌ๋Š” ํ–ฅํ›„, ํ”„๋ฆฌ์ŠคํŠธ๋ ˆ์Šค ๊ณต๋ฒ•์ด ์ ์šฉ๋˜๋Š” ์›์ „ ๊ฒฉ๋‚ฉ ๊ฑด๋ฌผ, ๊ต๋Ÿ‰, ์ผ๋ฐ˜ ๊ฑด์ถ•๋ฌผ ๋“ฑ ๋‹ค์–‘ํ•œ ๊ฑด์„ค ๋ถ„์•ผ์—์„œ ์˜ฌ๋ฐ”๋ฅธ ๊ณต๋ฒ• ์„ ์ •์„ ์œ„ํ•œ ๊ธฐ์ดˆ์  ์ง€ํ‘œ๋กœ ํ™œ์šฉ ๊ฐ€๋Šฅํ•˜๋ฉฐ, ํ”„๋ฆฌ์ŠคํŠธ๋ ˆ์ŠคํŠธ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ์˜ ๋‚ด๊ตฌ์„ฑ ํ–ฅ์ƒ๊ณผ ํ’ˆ์งˆ ํ–ฅ์ƒ์„ ์œ„ํ•œ ์ง€์นจ์˜ ํ™•๋ฆฝ ๋“ฑ์— ๊ธฐ์—ฌํ•  ์ˆ˜ ์žˆ์„ ๊ฒƒ์œผ๋กœ ๊ธฐ๋Œ€๋œ๋‹ค.

2. ์‹คํ—˜๊ฐœ์š”

2.1 ์‹œํ—˜ํŽธ ์ œ์ž‘

์‚ฌ์šฉ๋œ ์‹œํ—˜ํŽธ์€ Fig.3๊ณผ ๊ฐ™๋‹ค. ์‹œํ—˜ํŽธ ์ข…๋ฅ˜๋ณ„๋กœ 6๊ฐœ, ์ด 36๊ฐœ์˜ ์‹œํŽธ์„ ์ œ์ž‘ํ•˜์˜€์œผ๋ฉฐ, ์‹œํ—˜ํŽธ ์ข…๋ฅ˜๋ณ„ 3๊ฐœ ์‹œํŽธ์€ ์—ผ์†Œ์ด์˜จ์— ์˜ํ•œ ๋ถ€์‹ ์ด‰์ง„ ์‹คํ—˜์—, ๋‚˜๋จธ์ง€ 3๊ฐœ ์‹œํŽธ์€ ์—ผ์†Œ์ด์˜จ๊ณผ ์šฉ์กด ์‚ฐ์†Œ(dissolved oxygen, DO)์— ์˜ํ•œ ๋ถ€์‹ ์ด‰์ง„ ์‹คํ—˜์— ์‚ฌ์šฉํ•˜์˜€๋‹ค(Yoon et al. 2019). Fig.3(a)๋Š” ๊ณต์นญ ์ง๊ฒฝ 15.7 mm 7์—ฐ์„ (Grade 270)(ASTM A416 2016)์ธ ๊ฐ•์—ฐ์„  ์‹œํŽธ(bare strand, B)์œผ๋กœ์„œ ๋ณดํ˜ธ๊ณต๋ฒ•์ด ์ „ํ˜€ ์ ์šฉ๋˜์ง€ ์•Š์€ ์‹œํ—˜์ฒด์ด๋‹ค. ๋‹จ๋ฉด์ , ์ค‘๋Ÿ‰ ๋ฐ ํ™”ํ•™์  ์„ฑ๋ถ„์€ Table 1๊ณผ ๊ฐ™๋‹ค.

Fig. 3. Specimens for corrosion-prevention system

../../Resources/kci/JKCI.2019.31.6.557/fig3.png

Table 1. Properties of materials

Seven-wire strands

Strand properties

Section area (mm$^2$)

151.4

Weight (kg/m)

1.192

Diameter (mm)

15.83

Chemical composition (%)

Fe

98.17

C

0.82

Mn

0.73

Si

0.25

Cu

0.02

P

0.01

S

0.01

Cement grouting

w/c

0.33

HRWR (%)

3.0

VMAs (%)

0.5

Setting retarder (%)

0.5

HDPE plastic sheath

Density (g/cm$^3$)

0.992

Thickness (mm)

1.09

Fig.3(b)๋Š” ๊ฐ•์—ฐ์„ ์„ ๊ทธ๋ฆฌ์Šค๋กœ๋งŒ ์ฝ”ํŒ…ํ•œ ๊ฒƒ์ด๋ฉฐ, Fig.3(c)๋Š” ์‹œ๋ฉ˜ํŠธ๊ณ„ ํ‘œ์ค€ ๊ทธ๋ผ์šฐํŒ…๋œ ๋ถ€์ฐฉ์‹ ๊ณต๋ฒ•์„ ์ ์šฉํ•œ ๊ฒƒ์ด๋‹ค. ์›ํ˜• ์‹ค๋ฆฐ๋”ํ˜• ํŒŒ์ดํ”„๋กœ ๋ชฐ๋“œ๋ฅผ ๋งŒ๋“ค๊ณ  ์ •์ค‘์•™์— ๊ฐ•์—ฐ์„ ์„ ๊ฑฐ์ทจ์‹œํ‚จ ํ›„ ๊ทธ๋ผ์šฐํŒ…ํ•˜์˜€๋‹ค. ์ด๋•Œ ํ”ผ๋ณต๋‘๊ป˜๋Š” 15 mm์ด๋ฉฐ ๊ทธ๋ผ์šฐํŒ…์˜ ๋ฐฐํ•ฉ์€ Table 1์™€ ๊ฐ™๋‹ค. ๊ทธ๋ผ์šฐํŒ…์€ 28์ผ๊ฐ„ ๊ธฐ์ค‘ ์–‘์ƒํ•˜์˜€๊ณ  ์ดํ›„ ๋ถ€์‹์‹คํ—˜์„ ๊ฐœ์‹œํ•˜์˜€๋‹ค.

Fig.3(d)๋Š” ๊ฐ•์—ฐ์„ ์˜ ํ‘œ๋ฉด์„ ๊ทธ๋ฆฌ์Šค(grease)๋กœ ์ฝ”ํŒ…ํ•˜๊ณ  ์‹œ๋ฉ˜ํŠธ๊ณ„ ํ‘œ์ค€ ๊ทธ๋ผ์šฐํŒ…๋œ ์‹œํ—˜ํŽธ์œผ๋กœ์„œ ํ”ผ๋ณต๋‘๊ป˜๋Š” Fig.3(c) ์‹œํ—˜์ฒด์™€ ๋™์ผํ•˜๊ฒŒ 15 mm์ด๋‹ค. Fig.3(e)๋Š” ๊ฐ•์—ฐ์„ ์„ ๊ทธ๋ฆฌ์Šค๋กœ ์ฝ”ํŒ…ํ•˜๊ณ  ๊ณ ๋ฐ€๋„ ํด๋ฆฌ์—ํ‹ธ๋ Œ ํ”ผ๋ณต์žฌ์ธ HDPE ์‰ฌ์Šค๋กœ ๋น„๋ถ€์ฐฉ์‹ ๋ณดํ˜ธ๊ณต๋ฒ•์„ ์ ์šฉํ•œ ๊ฒƒ์œผ๋กœ, HDPE ์‰ฌ์Šค์˜ ๋ฌผ์„ฑ์€ Table 1๊ณผ ๊ฐ™๋‹ค. Fig.3(f)๋Š” ์ด์ƒ์˜ ๋ณดํ˜ธ๊ณต๋ฒ•์„ ๋ชจ๋‘ ์ ์šฉํ•œ ๊ฒƒ์œผ๋กœ์„œ, PSC ๊ฐ•์—ฐ์„ ์„ ๊ทธ๋ฆฌ์Šค๋กœ ์ฝ”ํŒ…ํ•˜๊ณ  HDPE ์‰ฌ์Šค ์ ์šฉ ํ›„, 15 mm ๋‘๊ป˜๋กœ ํ‘œ์ค€ ๊ทธ๋ผ์šฐํŒ…ํ•œ 3์ค‘ ๋น„๋ถ€์ฐฉ์‹ ๋ณดํ˜ธ๊ณต๋ฒ•์„ ์ ์šฉํ•œ ๊ฒƒ์ด๋‹ค. Fig.3(a)์˜ B ์‹œํ—˜ํŽธ์„ ์ œ์™ธํ•œ ๋ชจ๋“  ์‹œํ—˜ํŽธ์€ ๊ฐ•์—ฐ์„  ๋‹จ๋ถ€๊ฐ€ ๊ธฐ์ค‘ ๋ฐ ๋ถ€์‹์…€ ๋‚ด ์šฉ์•ก์— ๋…ธ์ถœ๋˜์ง€ ์•Š๋„๋ก ์‹œํ—˜ํŽธ์˜ ์–‘๋๋‹จ์„ ์—ํญ์‹œ๋กœ ๋ฐ€๋ด‰ํ•˜์˜€๋‹ค.

2.2 ๋ถ€์‹์…€์˜ ๊ตฌ์„ฑ

PTI M55.1-12 Appendix B(PTI 2012)์˜ ๊ฐ€์†๋ถ€์‹์‹œํ—˜๋ฒ•์„ ์ฐธ๊ณ ๋กœ Fig.4์™€ ๊ฐ™์€ ์‹คํ—˜์žฅ์น˜๋ฅผ ๊ตฌ์„ฑํ•˜์˜€๋Š”๋ฐ, ๋ถ€์‹ ์…€ ๋‚ด์— ์—ผ์†Œ์ด์˜จ ๋†๋„๋Š” ์ฆ๋ฅ˜์ˆ˜์— ์—ผํ™”๋‚˜ํŠธ๋ฅจ์„ ํ˜ผ์ž…ํ•˜์—ฌ 5 %๋กœ ์กฐ์„ฑํ•˜์˜€๋‹ค. ๋˜ํ•œ, ์‹คํ—˜์€ 2 ์‹œ๋ฆฌ์ฆˆ๋กœ ๋‚˜๋‰˜๋Š”๋ฐ ์‚ฐ์†Œ์˜ ์œ ์ž…์ด ์žˆ๋Š” ๊ฒƒ๊ณผ ์—†๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜๋‰˜์–ด ์ง„ํ–‰๋˜์—ˆ๋‹ค. ์‚ฐ์†Œ์˜ ์œ ์ž…๋ฐธ๋ธŒ๋ฅผ ์—ด์€ ํ›„, ์šฉ์กด ์‚ฐ์†Œ ์ธก์ •๊ธฐ๋กœ ์šฉ์กด ์‚ฐ์†Œ๊ฐ€ 21 ppm์ด ์กฐ์„ฑ๋˜์—ˆ์Œ์„ ํ™•์ธํ•˜์˜€๋‹ค.

Fig. 4. Accelerated corrosion test set-up

../../Resources/kci/JKCI.2019.31.6.557/fig4.png

2.3 ๋ถ€์‹๋„ ํ‰๊ฐ€๋ฐฉ๋ฒ•

2.3.1 ์ „๊ธฐํ™”ํ•™์  ๋ถ€์‹๋„ ํ‰๊ฐ€

๋‹ค์–‘ํ•œ ๋ถ€์‹๋ณดํ˜ธ๊ณต๋ฒ•์„ ์ ์šฉํ•œ ์‹œํ—˜ํŽธ์ด ๋ถ€์‹์…€์—์„œ์˜ ์ „๊ธฐํ™”ํ•™์ ์ธ ๋ฐ˜์‘์„ ์‚ดํŽด๋ณด๊ณ ์ž, ์ „๊ธฐํ™”ํ•™์  ๋ถ€์‹๋„ ํ‰๊ฐ€๋ฅผ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹์„ ์ „๊ธฐํ™”ํ•™์ ์ธ ๋ฐฉ๋ฒ•์— ์˜ํ•˜์—ฌ ์ •๋Ÿ‰์ ์œผ๋กœ ์ธก์ •ํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ๋ถ„๊ทน์ €ํ•ญ๋ฒ•์„ ์ ์šฉํ•˜์˜€๋‹ค. ๋ถ„๊ทน์ €ํ•ญ๋ฒ•์€ ๊ธˆ์†์˜ ๋งˆ์ดํฌ๋กœ ์…€๊ณผ ๋ฉ”ํฌ๋กœ ์…€์„ ์–‘์ธก ๋‹ค ์ธก์ •๊ฐ€๋Šฅํ•œ ๋ฐฉ๋ฒ•์œผ๋กœ์„œ, ๊ฐ•์—ฐ์„ ์˜ ๋ถ„๊ทน ์ €ํ•ญ์€ ๊ธˆ์†์ด ์ž์œ ๋ถ€์‹์ „์œ„ $E_{corr}$๋กœ๋ถ€ํ„ฐ ๋ถ„๊ทน๋  ๋•Œ ์ธ๊ฐ€ ์ „์•• $\Delta E$์™€ ์ „๋ฅ˜ ๋ณ€ํ™” $\Delta i$ ๊ฐ„์˜ ๋น„์œจ๋กœ ์ •์˜๋œ๋‹ค(Andrade and Gonzรกlez 1978). ์‹ (1)๊ณผ ๊ฐ™์ด ์ „์œ„-์ „๋ฅ˜์˜ ๊ธฐ์šธ๊ธฐ๋กœ๋ถ€ํ„ฐ ๋ถ„๊ทน์ด ๊ฒฐ์ •๋˜๋Š”๋ฐ, ์ด๋•Œ $i$๋Š” ์ „๋ฅ˜๋ฐ€๋„์ด๋‹ค.

(1)
$$ R_{p}=\left(\frac{\Delta E}{\Delta i}\right)_{\Delta E \rightarrow 0} $$

๋ณธ ์—ฐ๊ตฌ๋Š” ๋ถ„๊ทน์ €ํ•ญ๋ฒ•์— ๊ธฐ์ดˆํ•œ ๋ถ€์‹๋„ ์ธก์ •์„ ์œ„ํ•˜์—ฌ ์ •์ „์œ„๋ฐฉ๋ฒ•์„ ๊ตฌํ˜„ํ•˜์˜€๋‹ค. ์นด์šดํ„ฐ ์ „๊ทน์œผ๋กœ๋Š” ํ‘์—ฐ ๋ง‰๋Œ€, ๊ธฐ์ค€ ์ „๊ทน์œผ๋กœ ์นด๋กœ๋ง ์ „๊ทน์„ ๊ฐ๊ฐ ์ด์šฉํ•˜์˜€๊ณ , ์ž‘์šฉ ์ „๊ทน์€ ๊ฐ•์—ฐ์„  ์‹œํ—˜์ฒด์ด๋‹ค. ์กฐ์„ฑ๋œ ์ „๊ทน๋“ค์€ ์ •์ „์œ„์žฅ์น˜์— ์—ฐ๊ฒฐํ•˜์˜€๊ณ , ๋‹จ๊ธฐ๊ฐ„ ์ „๋ฅ˜๋Ÿ‰์ด ์ธ๊ฐ€๋จ์— ๋”ฐ๋ผ ์ž‘์šฉ ์ „๊ทน์˜ ์ „์œ„๊ฐ€ ์ธก์ •๋œ๋‹ค.

์ „๋ฅ˜-์ „์•• ๊ณก์„ ์˜ ์„ ํ˜• ๋ฒ”์œ„๋Š” ์ฒ ๊ทผ์˜ ๊ฒฝ์šฐ ๋ถ€์‹ ์ „์œ„์˜ 20~30 mV์ด๋ฉฐ, ๋งค์šฐ ๋ถ€์‹์†๋„๊ฐ€ ๋†’์„ ๊ฒฝ์šฐ์—๋Š” 100 mV์˜ ๋ฒ”์ฃผ์—์„œ๋„ ์„ ํ˜•์œผ๋กœ ์•Œ๋ ค์ ธ ์žˆ์œผ๋‚˜(Polder at el. 1993), ๊ฐ•์—ฐ์„ ์— ๋Œ€ํ•ด์„œ๋Š” ์ด์— ๋Œ€ํ•œ ๋ฒ”์œ„๋ฅผ ๋‹ค๋ฃฌ ์—ฐ๊ตฌ๊ฐ€ ๋ถ€์กฑํ•˜๋‹ค. ์ธ๊ฐ€ ์ „๋ฅ˜์˜ ๋ฒ”์œ„๊ฐ€ ์ง€๋‚˜์น˜๊ฒŒ ํฌ๋ฉด ์ „๋ฅ˜๋กœ ์ธํ•œ ๋ถ€์‹์ด ๋ฐœ์ƒํ•˜์—ฌ ์‹คํ—˜ ๊ฒฐ๊ณผ์— ์˜ํ–ฅ์„ ์ค„ ์ˆ˜ ์žˆ์–ด, ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์ „๋ฅ˜๋กœ ์ธํ•œ ๋ถ€์‹์„ ๋ฌด์‹œํ•  ์ˆ˜ ์žˆ๋Š” ์ˆ˜์ค€์ธ ์˜คํ”ˆํšŒ๋กœ ์ „์œ„ Eoc ๋Œ€๋น„ -10~+10 mV์˜ ์ „๋ฅ˜๋ฅผ ์ธ๊ฐ€์‹œ์ผฐ๋‹ค.

(2)
$$i_{corr}=\dfrac{B}{R_{p}}$$

์—ฌ๊ธฐ์„œ, $i_{corr}$: ๋ถ€์‹์ „๋ฅ˜ ๋ฐ€๋„(ยตA/cm$^2$),

$\quad$$\quad$ $B$: Stern-Geary ์ƒ์ˆ˜,

$\quad$$\quad$ $R_{p}$: ๋ถ„๊ทน์ €ํ•ญ(k๏ฝฅcm$^2$)์ด๋‹ค.

2.3.2 ๊ฐ•์—ฐ์„ ์˜ ์ค‘๋Ÿ‰๊ฐ์†Œ์œจ

๋ถ€์‹์‹คํ—˜ ์ „ํ›„, ๊ฐ•์—ฐ์„ ์˜ ๋ฌด๊ฒŒ๋ฅผ ์ธก์ •ํ•˜์—ฌ ์ค‘๋Ÿ‰๊ฐ์†Œ์œจ์„ ์ธก์ •ํ•˜์˜€์œผ๋ฉฐ, ์ด๋•Œ ์ธก์ •๊ฐ๋„๋Š” 0.1 mg ์ˆ˜์ค€์ด๋‹ค. ์ด‰์ง„ ์‹คํ—˜์ข…๋ฃŒ ํ›„ ์‹œํ—˜ํŽธ ๋‚ด ๊ฐ•์—ฐ์„ ์„ ์ฑ„์ทจํ•˜๊ณ , ๋ถ€์‹์ œ๊ฑฐ ์šฉ์•ก์„ ์ œ์กฐํ•˜์—ฌ ๊ฐ•์—ฐ์„ ์„ ์นจ์ง€ํ•˜๊ณ  ๋ถ€์‹๋ฌผ์„ ์ˆ˜์ง€์„ฑ ๋ธŒ๋Ÿฌ์‰ฌ๋กœ ์ œ๊ฑฐํ•˜์˜€์œผ๋ฉฐ ์ด ๊ณผ์ •์€ ASTM G1(ASTM G1-90 1999)์„ ์ฐธ๊ณ ํ•˜์˜€๋‹ค. ๋ถ€์‹์šฉ์•ก์€ HCl 1 โ„“์— ์‚ผ์‚ฐํ™”์•ˆํ‹ฐ๋ชฌ(Sb2O3) 20 g, ์—ผํ™”์ œ์ผ์ฃผ์„(SnCl2) 50 g์„ ํ˜ผ์ž…ํ•˜์˜€๋‹ค. ๊ฐ•์—ฐ์„ ์˜ ์ค‘๋Ÿ‰๊ฐ์†Œ๋Ÿ‰(ML)์€ ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

(3)
$$ML = W_{o}- W_{c}$$

์—ฌ๊ธฐ์„œ, $W_{o}$: ๋ถ€์‹์‹คํ—˜ ์ „ ๊ฐ•์—ฐ์„  ๋ฌด๊ฒŒ,

$\quad$$\quad$ $W_{c}$: ์‹คํ—˜์ข…๋ฃŒ ํ›„ ๋ถ€์‹๋ฌผ ์ œ๊ฑฐ๋œ ๊ฐ•์—ฐ์„  ๋ฌด๊ฒŒ์ด๋‹ค.

3. ์‹คํ—˜๊ฒฐ๊ณผ ๋ฐ ๊ณ ์ฐฐ

3.1 ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„

Fig.5๋Š” ์žฌ๋ น๋ณ„ ํ‰๊ท ์  ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ๊ตฌํ•œ ๊ฒฐ๊ณผ์ด๋‹ค. ์—ผ์ˆ˜๋กœ๋ถ€ํ„ฐ ์–ด๋–ค ๋ณดํ˜ธ๊ณต๋ฒ•๋„ ์ ์šฉํ•˜์ง€ ์•Š์€ ๊ฐ•์—ฐ์„ ์€ ๋†’์€ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๊ฐ€ ์ธก์ •๋˜์—ˆ๋Š”๋ฐ, ์ด‰์ง„์‹คํ—˜ 15์ผ ๋งŒ์— 80 ยตA/cm$^2$ ์ด์ƒ์œผ๋กœ ์ƒ๋‹นํ•œ ์ˆ˜์น˜๋ฅผ ๋ณด์˜€๋‹ค. ๊ทธ๋Ÿฌ๋‚˜, ๋ถ€์‹๋ฐฉ์ง€ ๊ณต๋ฒ•์„ ์ ์šฉํ•œ ๋‹ค๋ฅธ ์‹œํ—˜์ฒด๋Š” ๋น„๊ต์  ๊ฒฝ๋ฏธํ•œ ๋ถ€์‹์†๋„๋ฅผ ๋ณด์˜€๋Š”๋ฐ, ๊ทธ๋ฆฌ์Šค ๋ฐ ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ…์„ ๊ฐ๊ฐ ์ ์šฉํ•œ G์™€ C ์‹œํ—˜ํŽธ์€ ๋Œ€์ฒด๋กœ ๊ฑฐ์˜ ๋Œ€๋“ฑํ•œ ์ˆ˜์ค€์˜ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ๋ณด์˜€๋‹ค. ์ด๋Ÿฌํ•œ ๊ฒฝํ–ฅ์€ 30~60์ผ์ด ๊ฒฝ๊ณผํ•˜๋ฉด์„œ๋„ ๊ทธ ์ถ”์ด๊ฐ€ ๋น„์Šทํ•˜์˜€๋‹ค.

์—ผ์ˆ˜์™€ ์šฉ์กด ์‚ฐ์†Œ์— ์˜ํ•œ ๋ถ€์‹ ์ด‰์ง„์‹คํ—˜์—์„œ๋Š” ๊ฐ•์—ฐ์„ ๋งŒ์œผ๋กœ ์ธก์ •๋œ B ์‹œํ—˜ํŽธ์€ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๊ฐ€ ๋งค์šฐ ๋†’๊ฒŒ ์ƒ์Šนํ•˜์—ฌ ์ด‰์ง„ 2์ฃผ ๋งŒ์— 200 ยตA/cm$^2$ ๋‚ด์™ธ์— ๋„๋‹ฌํ•˜์˜€๋Š”๋ฐ, ์ด๋Š” Fig.5์˜ ์—ผ์†Œ์ด์˜จ์œผ๋กœ๋งŒ ๋ถ€์‹๋œ ๊ฐ•์—ฐ์„ ๊ณผ ๋น„๊ตํ•˜๋ฉด 3๋ฐฐ ๊ทœ๋ชจ์˜ ๋ถ€์‹์†๋„์ด๋‹ค. ๋”ฐ๋ผ์„œ, ์—ผ์ˆ˜ ๋‚ด ์šฉ์กด ์‚ฐ์†Œ๊ฐ€ ์กด์žฌํ•˜๋ฉด ๋งค์šฐ ๊ฐ€ํ˜นํ•œ ๋ถ€์‹ํ™˜๊ฒฝ์ด ์กฐ์„ฑ๋˜์–ด ๋‹จ๊ธฐ๊ฐ„ ๋‚ด์— ํšจ์œจ์ ์ธ ๋ถ€์‹์„ฑ๋Šฅ ํ‰๊ฐ€์— ์œ ํšจํ•  ๊ฒƒ์œผ๋กœ ์ƒ๊ฐ๋œ๋‹ค. ์ด์˜จ๊ณผ ๊ธฐ์ฒด์˜ ํ™•์‚ฐ์†๋„๋ฅผ ๋น„๊ตํ•ด๋ณด๋ฉด ์•ฝ 10,000๋ฐฐ ์ˆ˜์ค€์œผ๋กœ ์‚ฐ์†Œ๊ฐ€ ์—ผ์†Œ์ด์˜จ์˜ ํ™•์‚ฐ์†๋„๋ณด๋‹ค ๋งค์šฐ ๋น ๋ฅด๋ฏ€๋กœ ์—ผ์ˆ˜์— ์กด์žฌํ•˜๋Š” ์šฉ์กด ์‚ฐ์†Œ๋Ÿ‰์„ ์ฆ๊ฐ€์‹œํ‚ค๋ฉด ์‹œํ—˜ํŽธ์— ์นจํˆฌํ•˜์—ฌ ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹์„ ํšจ๊ณผ์ ์œผ๋กœ ์ด‰์ง„ํ•˜๋Š” ์‹คํ—˜ ์„ค๊ณ„๊ฐ€ ๊ฐ€๋Šฅํ•  ๊ฒƒ์œผ๋กœ ์ƒ๊ฐ๋œ๋‹ค(Cussler 2009). ๋˜ํ•œ, ์—ผ์ˆ˜ ์นจ์ง€ ์‹คํ—˜๊ฒฐ๊ณผ์™€ ๋Œ€๋น„ํ•˜์—ฌ ์—ผ์ˆ˜์™€ ์šฉ์กด ์‚ฐ์†Œ์— ์˜ํ•œ ์‹คํ—˜์—์„œ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๊ฐ€ ์ฃผ๋ชฉํ•  ๋งŒํ•˜๊ฒŒ ์ƒ์Šนํ•œ ๊ฒƒ์€ ๊ทธ๋ฆฌ์Šค๋งŒ์œผ๋กœ ๋„๋ง‰ ์ฒ˜๋ฆฌ๋œ G ์‹œํ—˜ํŽธ์ด๋‹ค. ์ด๋Š” ์‚ฐ์†Œ ๊ธฐํฌ๊ฐ€ ๊ตญ๋ถ€์ ์œผ๋กœ ๊ทธ๋ฆฌ์Šค ๋„๋ง‰์„ ๋ฌผ๋ฆฌ์ ์œผ๋กœ ํƒ€๊ฒฉ ์†์ƒ์‹œ์ผœ์„œ ๊ทธ๋ฆฌ์Šค ๋ณธ์œ ์˜ ๋„๋ง‰๋ณดํ˜ธ์„ฑ๋Šฅ์„ ์ €ํ•ด์‹œ์ผฐ๊ธฐ ๋•Œ๋ฌธ์œผ๋กœ ์ƒ๊ฐ๋œ๋‹ค.

Fig. 5. Corrosion current density of tendon with elapsed time

../../Resources/kci/JKCI.2019.31.6.557/fig5.png

Fig. 6. Average $i_{corr}$ value

../../Resources/kci/JKCI.2019.31.6.557/fig6.png

ํ•œํŽธ, ์‹œ๊ฐ„์— ๋”ฐ๋ฅธ ๊ฑฐ๋™ ์ถ”์ด๋„ ๊ด€์ฐฐํ•˜์˜€๋Š”๋ฐ, ์ด๋Š” ์‹œํ—˜ํŽธ๋ณ„ ์ถ”์ด์™€๋Š” ๋‹ค์†Œ ์ƒ์ดํ•˜์˜€๋‹ค. ์—ผ์ˆ˜์— ์˜ํ•œ ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹์‹คํ—˜์—์„œ๋Š”, ๊ทธ๋ฆฌ์Šค๋กœ ๋„๋ง‰์„ ํ˜•์„ฑํ•œ ๊ฒƒ์€ ์‹œ๊ฐ„์ด ๊ฒฝ๊ณผํ•˜๋ฉด์„œ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๊ฐ€ ์ƒ์Šนํ•˜๋Š” ์ถ”์ด๋ฅผ ๋ณด์ธ ๋ฐ˜๋ฉด, ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ…์„ ์ ์šฉํ•œ ์‹œํ—˜ํŽธ์€ ์‹œ๊ฐ„์— ๋”ฐ๋ผ ๊ฐ์†Œํ•˜๋Š” ๊ฒฝํ–ฅ์ด ๊ด€์ฐฐ๋˜์—ˆ๋‹ค. ์ด๋Š” ๊ทธ๋ฆฌ์Šค๊ฐ€ ์ดˆ๊ธฐ์—๋Š” ํšจ์œจ์ ์œผ๋กœ ์—ผ์†Œ ์œ ์ž…์„ ์ฐจ๋‹จํ•ด์ฃผ์ง€๋งŒ, ์‹œ๊ฐ„์ด ์ง€๋‚˜๋ฉด์„œ ์œ ์ž…์„ ํ—ˆ์šฉํ•˜๊ธฐ ๋•Œ๋ฌธ์œผ๋กœ ์ถ”์ •๋œ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜, ๊ทธ๋ฆฌ์Šค๊ฐ€ ๊ฐ–๋Š” ์œ ํ•ด ์ด์˜จ์— ๋Œ€ํ•œ ์ฐจ๋‹จํšจ๊ณผ์˜ ์ง€์†์„ฑ์€ ์ด์˜จ์˜ ๋†๋„ ๋ฐ ๊ทธ๋ฆฌ์Šค์˜ ์ข…๋ฅ˜์™€ ๋„๋ง‰ ๋‘๊ป˜ ๋“ฑ์— ๋”ฐ๋ผ ๋‹ค๋ฅผ ์ˆ˜ ์žˆ์œผ๋ฏ€๋กœ, ํ–ฅํ›„ ๋…ผ๋ฌธ์—์„œ ์ด๋ฅผ ์ง€์†ํ•ด์„œ ๋‹ค๋ฃฐ ์˜ˆ์ •์ด๋‹ค. ํ•œํŽธ, ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ…์„ ์ ์šฉํ•œ ์‹œํ—˜์ฒด๋Š” ํ‘œ๋ฉด์— ๋ฏธ์„ธํ•œ ๊ท ์—ด์ด ์กด์žฌํ•˜์˜€๋Š”๋ฐ, ์ด๋ฅผ ์‹ค ๊ตฌ์กฐ๋ฌผ์˜ ์‹œ๊ณต์„ฑ๊ณผ ๋™์ผํ•œ ์ƒํ™ฉ์œผ๋กœ ๊ฐ„์ฃผํ•˜์—ฌ ์‹คํ—˜ํ•˜์˜€๋‹ค. ๋ถ€์‹๋ฐ˜์‘์—์„œ ์Œ๊ทน๊ณผ ์–‘๊ทน ๊ฑฐ๋™์˜ ์ฐจ์ด๋Š” ๊ฐ•์—ฐ์„ ์˜ ํ‘œ๋ฉด์ƒํƒœ์™€ ๊ด€๋ จ์ด ์žˆ๋‹ค. ๊ฒฝํ™”๋œ ๊ทธ๋ผ์šฐํŒ… ํ‘œ๋ฉด์˜ ๋ฏธ์„ธ๊ท ์—ด์„ ํ†ตํ•ด ์—ผ์†Œ์ด์˜จ์ด ๋น ๋ฅด๊ฒŒ ์นจํˆฌํ•˜์—ฌ ๋ถ€์‹์ด ์ง„ํ–‰๋˜์—ˆ์ง€๋งŒ, ์‹œ๊ฐ„์ด ๊ฒฝ๊ณผํ•˜๋ฉด์„œ ๊ฐ•์—ฐ์„  ํ‘œ๋ฉด์˜ ๋ถ€์‹์ธต์ด ์ถ”๊ฐ€์ ์ธ ์—ผ์†Œ์ด์˜จ์˜ ์œ ์ž…์„ ์ผ์‹œ์ ์œผ๋กœ ์ฐจ๋‹จํ•˜์—ฌ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๊ฐ€ ๋‹ค์†Œ ๊ฐ์†Œํ•œ ๊ฒƒ์œผ๋กœ ์ƒ๊ฐ๋œ๋‹ค. ๋งŒ์ผ, ํ˜„์žฅ์—์„œ ๊ทธ๋ผ์šฐํŒ…์— ๋ฏธ์„ธ๊ท ์—ด์ด ์กด์žฌํ•˜์ง€ ์•Š๋„๋ก ์šฐ์ˆ˜ํ•œ ๊ธฐ์ˆ ์„ ๋„์ž…ํ•˜๊ณ  ์ •์„ฑ ๋“ค์—ฌ ์‹œ๊ณตํ•œ๋‹ค๋ฉด ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ…์€ ๊ทธ๋ฆฌ์Šค๋ณด๋‹ค ๋ฐฉ์‹ํšจ๊ณผ๊ฐ€ ๋›ฐ์–ด๋‚  ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค. ๋˜ํ•œ, HDPE ์‰ฌ์Šค(๊ณ ๋ฐ€๋„ ํด๋ฆฌ์—ํ‹ธ๋ Œ ํ”Œ๋ผ์Šคํ‹ฑ ์‰ฌ์Šค)๋ฅผ ์ด์šฉํ•œ G-H์™€ G-H-C ์‹œํ—˜ํŽธ์€ ๊ฐ€์žฅ ๋‚ฎ์€ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ๋ณด์—ฌ์„œ ์‹คํ—˜ ๋ฒ”์ฃผ ๋‚ด์˜ ์‹œํ—˜์ฒด ๊ฐ€์šด๋ฐ ๊ฐ€์žฅ ์šฐ์ˆ˜ํ•œ ๋ถ€์‹ ๋ณดํ˜ธ๋Šฅ๋ ฅ์ด ์žˆ๋Š” ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

์—ผ์ˆ˜์™€ ์šฉ์กด ์‚ฐ์†Œ์— ์˜ํ•œ ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹์˜ ์‹œ๊ฐ„์  ์ถ”์ด๋ฅผ ๊ด€์ฐฐํ•œ ๊ฒฐ๊ณผ์—์„œ๋„ ์‹œํ—˜ํŽธ๋ณ„ ์ถ”์ด์™€๋Š” ๋‹ค์†Œ ์ƒ์ดํ•˜์˜€๋‹ค. G ์‹œํ—˜ํŽธ์€ ์ดˆ๊ธฐ์—๋Š” ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๊ฐ€ ๋†’์•˜์œผ๋‚˜ 30์ผ์ด ๊ฒฝ๊ณผํ•˜๋ฉด์„œ ๋‹ค์†Œ ๊ฐ์†Œํ•˜๋Š” ๊ฒฝํ–ฅ์„ ๋ณด์˜€๋‹ค. ์ด๋Š” ์•ž์„œ ์–ธ๊ธ‰ํ•œ ๋ฐ”์™€ ๊ฐ™์ด ์†์ƒ์„ ์ž…์€ ๋ถ€์œ„์—์„œ ์ด๋ฏธ ๊ฐ•์—ฐ์„  ํ‘œ๋ฉด์— ๋ถ€์‹์ธต์ด ํ˜•์„ฑ๋˜์–ด ์—ผ์†Œ ๋ฐ ์‚ฐ์†Œ์˜ ์œ ์ž…์— ์ผ์‹œ์ ์ธ ์ œ์–ดํšจ๊ณผ๋ฅผ ๋ณด์ธ ๊ฒƒ์œผ๋กœ ์ƒ๊ฐ๋œ๋‹ค. ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ… ๋œ C ์‹œํ—˜ํŽธ๋„ ์‹œ๊ฐ„ ๊ฒฝ๊ณผ์— ๋”ฐ๋ผ ๋‹ค์†Œ ๊ฐ์†Œํ•˜๋Š” ์ถ”์ด๋ฅผ ๋ณด์˜€์œผ๋‚˜, G ์‹œํ—˜ํŽธ์˜ ๊ทธ๋ฆฌ์Šค๋ณด๋‹ค๋Š” ์—ผ์†Œ ๋ฐ ์‚ฐ์†Œ์˜ ๋ถ€์‹์— ๋Œ€ํ•˜์—ฌ ๊ฐ•์—ฐ์„ ์„ ์ž˜ ๋ณดํ˜ธํ•˜์˜€๋‹ค. ์ด๋ฅผ ๋ณ‘ํ–‰ ์ ์šฉํ•œ G-C ์‹œํ—˜ํŽธ์ด ๋‹ค์Œ ์ˆœ์ด์—ˆ์œผ๋ฉฐ HDPE ์‰ฌ์Šค๋ฅผ ์ด์šฉํ•œ G-H์™€ G-H-C ์‹œํ—˜ํŽธ์€ ๊ฑฐ์˜ ์œ ์‚ฌํ•œ ์ˆ˜์ค€์œผ๋กœ HDPE๋Š” ์—ผ์†Œ์นจํˆฌ ๋ฐ ์‚ฐ์†Œ ์œ ์ž…์— ๋†’์€ ์ฐจ๋‹จ์„ฑ๋Šฅ์„ ๋ณด์œ ํ•˜์—ฌ ๋งค์šฐ ์šฐ์ˆ˜ํ•œ ๋ถ€์‹ ๋ณดํ˜ธ๋Šฅ๋ ฅ์„ ๋ณด์˜€๋‹ค. ๊ทธ๋Ÿฐ๋ฐ, HDPE๋Š” ์ ˆ์—ฐ์„ฑ์„ ๊ฐ–๋Š” ์žฌ๋ฃŒ์ด๊ธฐ ๋•Œ๋ฌธ์— ์ „๊ธฐํ™”ํ•™์  ํ‰๊ฐ€๋ฅผ ์ˆ˜ํ–‰ํ•˜๋Š”๋ฐ ํ•ฉ๋ฆฌ์ ์ธ ๋ฐ์ดํ„ฐ๋ฅผ ๊ธฐ๋Œ€ํ•˜๊ธฐ ์–ด๋ ค์šธ ๊ฒƒ์œผ๋กœ ์ƒ๊ฐ๋˜์—ˆ์œผ๋‚˜, ์‹ค์งˆ์ ์œผ๋กœ๋Š” ๋‚ฎ์€ ์ˆ˜์ค€์˜ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๊ฐ€ ์ธก์ •๋˜์—ˆ๋‹ค. ์ด๋Š” ์—ํญ์‹œ๋กœ ์‹ค๋งํ•œ ์‹œํ—˜ํŽธ์˜ ์ƒ๏ฝฅํ•˜๋‹จ์—์„œ ์ˆ˜์šฉ์•ก์ด ์นจํˆฌํ•˜์—ฌ ๋ฐœ์ƒํ•˜์˜€๊ธฐ ๋•Œ๋ฌธ์œผ๋กœ ์ƒ๊ฐ๋œ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜, G-H์™€ G-H-C ์‹œํ—˜ํŽธ์˜ ๊ฒฐ๊ณผ๋ฅผ ๋น„๊ตํ•ด๋ณด๋ฉด ์ถ”์ •ํ•  ์ˆ˜ ์žˆ๋“ฏ์ด, ์ผ๋‹จ HDPE ์‰ฌ์Šค๋ฅผ ์‚ฌ์šฉํ•˜๋ฉด ๊ด€์™ธ๋ถ€๋ฅผ ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ… ์ฒ˜๋ฆฌ์˜ ์—ฌ๋ถ€์™€ ์ƒ๊ด€์—†์ด HDPE๊ฐ€ ๋งค์šฐ ์šฐ์ˆ˜ํ•œ ๋ถ€์‹ ๋ณดํ˜ธํšจ๊ณผ๋ฅผ ๊ฐ–๋Š” ๊ฒƒ์œผ๋กœ ์ƒ๊ฐ๋œ๋‹ค.

Fig.5์˜ ๊ทธ๋ฆผ์„ ํ† ๋Œ€๋กœ ๊ฐ ์‹œํ—˜ํŽธ๋ณ„ ํ‰๊ท ์ ์ธ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ๊ตฌํ•œ ๊ฒƒ์ด Fig.6์ด๋‹ค. ํ‰๊ท ์ ์ธ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๊ฐ€ ๊ฐ€์žฅ ๋†’์€ ์ˆœ์œผ๋กœ ์ •๋ฆฌํ•˜๋ฉด, ๊ทธ๋ฆฌ์Šค ๋„๋ง‰ํ•œ G ์‹œํ—˜ํŽธ๊ณผ ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ…ํ•œ C ์‹œํ—˜ํŽธ์ด ์—ผ์ˆ˜์— ์˜ํ•œ ๋ถ€์‹ ์‹คํ—˜์—์„œ๋Š” ๋™์ผํ•œ ์ˆ˜์ค€์ด์ง€๋งŒ, ์šฉ์กด ์‚ฐ์†Œ์™€ ๋ณ‘ํ–‰ํ•œ ์‹คํ—˜์—์„œ๋Š” ๊ทธ๋ผ์šฐํŒ…ํ•œ ๊ฒƒ์ด ๋šœ๋ ทํ•˜๊ฒŒ ๋” ๋‚ฎ์€ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ๋ณด์˜€๋‹ค. ๊ทธ๋ฆฌ์Šค์™€ ๊ทธ๋ผ์šฐํŒ…์„ ๋™์‹œ ์ ์šฉํ•œ G-C ์‹œํ—˜ํŽธ์ด ๋‹ค์Œ ์ˆœ์ด์—ˆ์œผ๋ฉฐ, ๊ฐ€์žฅ ๋‚ฎ์€ ํ‰๊ท ์ ์ธ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋Š” G-H์™€ G-H-C ์‹œํ—˜ํŽธ์—์„œ ๊ด€์ฐฐ๋˜์—ˆ๋‹ค.

3.2 ๊ฐ•์—ฐ์„ ์˜ ์ค‘๋Ÿ‰ ๊ฐ์†Œ

Fig.7์€ ์‹คํ—˜์ข…๋ฃŒ ํ›„ ๊ฐ•์—ฐ์„  ํ‘œ๋ฉด์˜ ๋ถ€์‹๋ฌผ์„ ์ œ๊ฑฐํ•˜๊ณ  ์ธก์ •๋œ ๊ฐ์†Œ๋œ ์ค‘๋Ÿ‰์„ ์ •๋ฆฌํ•œ ๊ฒฐ๊ณผ์ด๋‹ค. ์–ด๋–ค ๋ถ€์‹ ๋ณดํ˜ธ๊ณต๋ฒ•๋„ ์ ์šฉํ•˜์ง€ ์•Š์€ B ์‹œํ—˜ํŽธ์€ ๋†’์€ ์ค‘๋Ÿ‰๊ฐ์†Œ์œจ์ด ์ธก์ •๋˜์—ˆ๋Š”๋ฐ, ์—ผ์†Œ๋งŒ์œผ๋กœ ๋ถ€์‹๋œ ๊ฒƒ๋ณด๋‹ค ์‚ฐ์†Œ์™€ ๋™๋ฐ˜์ž‘์šฉ์‹œ 2๋ฐฐ์— ์ƒ์‘ํ•˜๋Š” ๊ฒฐ๊ณผ๋ฅผ ๋ณด์˜€๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ HDPE ์‰ฌ์Šค๋ฅผ ์ฒ˜๋ฆฌํ•œ G-H์™€ G-H-C ์‹œํ—˜ํŽธ์€ ์—ผ์†Œ ๋ฐ ์‚ฐ์†Œ์œ ์ž…์— ๋”ฐ๋ฅธ ์ฐจ์ด๊ฐ€ ๊ฑฐ์˜ ๋™์ผํ•œ ์ˆ˜์ค€์œผ๋กœ์„œ, HDPE ๋„๋ง‰์ด ์ด์˜จ ๋ฐ ๊ธฐ์ฒด์˜ ์นจํˆฌ์— ๋งค์šฐ ํšจ๊ณผ์ ์ž„์ด ์ž…์ฆ๋˜์—ˆ๋‹ค. ๊ทธ๋ฆฌ์Šค์™€ ๊ทธ๋ผ์šฐํŒ…์„ ๋™์‹œ์— ์ ์šฉํ•œ G-C ์‹œํ—˜ํŽธ์€ ์—ผ์†Œ๋งŒ์— ์˜ํ•œ ๋ถ€์‹๋Ÿ‰์€ HDPE ์‰ฌ์Šค๋ฅผ ์‚ฌ์šฉํ•œ ๊ฒƒ๊ณผ ์œ ์‚ฌํ•œ ์ˆ˜์ค€์ด์ง€๋งŒ, ์‚ฐ์†Œ๊นŒ์ง€ ๋™๋ฐ˜ํ•˜๋Š” ๋ณตํ•ฉ์ ์ธ ์—ดํ™”ํ™˜๊ฒฝ์—์„œ๋Š” ์ค‘๋Ÿ‰ ๊ฐ์†Œ๋Ÿ‰์ด ๋‹ค์†Œ ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ๋ฌด์—‡๋ณด๋‹ค ๊ทธ๋ฆฌ์Šค๋กœ ์ฝ”ํŒ…๋œ G ์‹œํ—˜ํŽธ์€ ์—ผ์†Œ์ด์˜จ ์นจ์ง€๋Œ€๋น„ ์‚ฐ์†Œ ์œ ์ž…๋œ ๊ฒƒ์ด 20๋ฐฐ์— ๋‹ฌํ•˜๋Š” ๋งค์šฐ ๋†’์€ ์ค‘๋Ÿ‰ ๊ฐ์†Œ๋ฅผ ๋ณด์˜€๋‹ค.

Fig. 7. Metal loss of strands

../../Resources/kci/JKCI.2019.31.6.557/fig7.png

์ด์ƒ์˜ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ํ† ๋Œ€๋กœ ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹์„ ์ œ์–ดํ•  ์ˆ˜ ์žˆ๋Š” ํšจ๊ณผ์ ์ธ ๊ณต๋ฒ•์˜ ์ˆœ์œผ๋กœ, ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ… ์ฒ˜๋ฆฌ์™€ ๋ฌด๊ด€ํ•˜๊ฒŒ HDPE ์‰ฌ์Šค์— ๊ฐ•์—ฐ์„ ์— ๊ทธ๋ฆฌ์Šค๋กœ ๋„๋ง‰์ฒ˜๋ฆฌ๋ฅผ ํ•œ ๊ฒƒ, ๊ทธ๋ฆฌ์Šค ์ฒ˜๋ฆฌ๋œ ๊ฐ•์—ฐ์„ ์„ ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ…ํ•œ ๊ฒƒ, ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ…ํ•œ ๊ฒƒ, ๊ทธ๋ฆฌ์Šค๋กœ ๋„๋ง‰์ฒ˜๋ฆฌํ•œ ๊ฒƒ์˜ ์ˆœ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ๋”ฐ๋ผ์„œ, HDPE ์‰ฌ์Šค๊ฐ€ ๊ฐ•์—ฐ์„ ์˜ ๋‚ด๋ถ€์‹์„ฑ๋Šฅ ํ–ฅ์ƒ์— ๋งค์šฐ ์šฐ์ˆ˜ํ•œ ๊ฒƒ์œผ๋กœ ๊ท€๊ฒฐ๋œ๋‹ค. HDPE๋Š” ์—ด๊ฐ€์†Œ์„ฑ ์ˆ˜์ง€๋กœ์„œ, ๋‚ด์ถฉ๊ฒฉ์„ฑ ๋ฐ ํ™”ํ•™์  ์ €ํ•ญ์„ฑ์ด ๋†’์„ ๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ๋‚ด์นจํˆฌ์„ฑ๋„ ์šฐ์ˆ˜ํ•˜๋‹ค. HDPE์˜ ์ˆ˜๋ถ„ ๋ฐ ์‚ฐ์†Œํˆฌ๊ณผ์œจ์€ ๋‹ค๋ฅธ ๊ณ ๋ถ„์ž ์ˆ˜์ง€ ๋ณด๋‹ค๋„ 3~50 % ์ดํ•˜์˜ ๋‚ฎ์€ ์ˆ˜์ค€์ธ 148๊ณผ 63,150 ยตg/m2/day๋กœ ๊ฐ๊ฐ ์•Œ๋ ค์กŒ๋‹ค(PPD 2019). ๋”ฐ๋ผ์„œ, HDPE๋Š” ๋งค์šฐ ์šฐ์ˆ˜ํ•œ ๋‚ด๋ถ€์‹์„ฑ๋Šฅ์ด ๊ธฐ๋Œ€๋˜์ง€๋งŒ, ํ˜„์žฅ์‹œ๊ณต์‹œ HDPE ์‰ฌ์Šค ํ‘œ๋ฉด์—์„œ ๋ฐœ์ƒํ•  ์ˆ˜ ์žˆ๋Š” ๊ท ์—ด, ๊ฐˆ๋ผ์ง๊ณผ ๊ฐ™์€ ํŒŒ์†์ด ๋‚ด๋ถ€์‹์„ฑ์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ ๋ฐ ๋‚ด๊ตฌ์„ฑ ํ™•๋ณด๋ฅผ ์œ„ํ•œ HDPE์˜ ์ ๋‹นํ•œ ์‰ฌ์Šค ๋‘๊ป˜๋ฅผ ์‚ฐ์ •ํ•˜๋Š” ์—ฐ๊ตฌ๊ฐ€ ์ถ”๊ฐ€๋กœ ํ•„์š”ํ•  ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

3.3 ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„ ๋Œ€๋น„ ์ค‘๋Ÿ‰๊ฐ์†Œ

๋ถ€์‹๋ณดํ˜ธ๊ณต๋ฒ•์ด ์ ์šฉ๋œ ์‹œํ—˜ํŽธ์ด ์—ผ์†Œ์ด์˜จ ๋ฐ ์‚ฐ์†Œ์™€ ์ ‘์ด‰ํ•˜๋Š” ์ˆœ๊ฐ„๋ถ€ํ„ฐ ์ฆ‰๊ฐ์ ์œผ๋กœ ํ™œ์„ฑํ™”๋˜๋Š” ๊ฒƒ์ด ์•„๋‹ˆ๋ผ, ์ดˆ๊ธฐ์—๋Š” ๋ณดํ˜ธ๋˜์ง€๋งŒ ์ดํ›„ ์ง€์†์ ์ธ ์ด‰์ง„์— ์˜ํ•˜์—ฌ ๋ถ€์‹์ด ๊ฐœ์‹œ๋œ๋‹ค. ์ „๊ธฐํ™”ํ•™ ๋ฐ˜์‘์—์„œ๋Š” ๋ฐ˜์‘๊ฒฝ๊ณ„๋ฉด์œผ๋กœ๋ถ€ํ„ฐ ์ด๋™ํ•˜๋Š” ์ „์ž์˜ ํ๋ฆ„์œผ๋กœ ๋ถ€์‹์†๋„๊ฐ€ ์ธก์ •๋œ๋‹ค. ๊ทธ๋ž˜์„œ ์ „์ž์˜ ์ด๋™์€ ์ „๋ฅ˜์— ์˜ํ•˜์—ฌ ์ธก์ •๋˜๊ณ  ์ „๊ธฐํ™”ํ•™ ๋ฐ˜์‘์—์„œ ์ „๋ฅ˜์™€ ๋ฐ˜์‘๋ฌผ์งˆ๋Ÿ‰ ๊ฐ„์˜ ๊ด€๊ณ„๋ฅผ ์ด์šฉํ•˜์—ฌ ๋ถ€์‹ ๋„๋ž˜ ์‹œ์˜ ๋ถ€์‹ ์ „๋ฅ˜๋ฐ€๋„๋ฅผ ์ถ”์ •ํ•˜์˜€๋‹ค.

๋จผ์ €, ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹ ์ „๋ฅ˜๋ฐ€๋„์™€ ์ค‘๋Ÿ‰๊ฐ์†Œ์˜ ์ƒํ˜ธ๊ด€๊ณ„๋ฅผ ํŒจ๋Ÿฌ๋ฐ์ด ๋ฒ•์น™์œผ๋กœ๋ถ€ํ„ฐ ์œ ๋„ํ•˜์—ฌ ๋ถ€์‹ ์‹œ์ž‘์‹œ๊ธฐ์™€ ์ž„๊ณ„ ๋ถ€์‹ ์ „๋ฅ˜๋ฐ€๋„๋ฅผ ๋„์ถœํ•˜์˜€๋‹ค. ์‹คํ—˜์ข…๋ฃŒ ํ›„ ์ค‘๋Ÿ‰ ๊ฐ์†Œ์™€ ๋ถ€์‹์†๋„(CR)์˜ ๊ด€๊ณ„๋Š” ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

(4)
$$ \mathrm{CR}(\mathrm{mm} / \mathrm{year})=k \frac{M L}{\rho \cdot A \cdot t} $$

์—ฌ๊ธฐ์„œ, ML: ๊ฐ•์—ฐ์„ ์˜ ๊ฐ์†Œ๋œ ๋ฌด๊ฒŒ(mg),

$\quad$$\quad$ k : ์ƒ์ˆ˜(87.6),

$\quad$$\quad$ A: ๊ฐ•์—ฐ์„ ์˜ ํ‘œ๋ฉด์ (cm$^2$),

$\quad$$\quad$ t : ๋ถ€์‹ ์‹คํ—˜๊ธฐ๊ฐ„(hrs),

$\quad$$\quad$ $\rho$ : ๊ฐ•์—ฐ์„ ์˜ ๋ฐ€๋„(=7.85 g/cm$^3$).

์ด๋•Œ, ํŒจ๋Ÿฌ๋ฐ์ด ๋ฒ•์น™์œผ๋กœ๋ถ€ํ„ฐ ๋‹จ๋ฉด๊ฒฐ์†์œจ๊ณผ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„ ์˜ ์ƒ๊ด€๊ด€๊ณ„๋Š” ์‹ (5)์™€ ๊ฐ™๋‹ค(Broomfield 1997).

(5)
$$Corrosion \enspace current \enspace density \enspace 1.0 ยตA/cm^2\\ = Section \enspace loss 1.1ร—10^{-2} mm/ year$$

์ˆœ๊ฐ„์ ์ธ ์ธก์ •๋œ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ์ „์ฒด ์‹คํ—˜๊ธฐ๊ฐ„ ๋™์•ˆ ๊ฐ•์—ฐ์„ ์˜ ๊ฐ์†Œ๋œ ๋ฌด๊ฒŒ๋Š” ์‹ (6)๊ณผ ๊ฐ™๋‹ค.

(6)
$$ M L=4.3 \cdot 10^{-2} \rho \cdot A \int_{t_{e}}^{t_{i}} i_{c o r r}(t) d t $$

์—ฌ๊ธฐ์„œ, $t_i$ : ๋ถ€์‹๊ฐœ์‹œ ์‹œ๊ฐ„,

$\quad$$\quad$ $t_e$ : ์‹คํ—˜ ์ข…๋ฃŒ์‹œ๊ฐ„์ด๋‹ค.

๊ฐ•์—ฐ์„ ์˜ ์ค‘๋Ÿ‰๊ฐ์†Œ๋Ÿ‰๊ณผ ์‹œ๊ฐ„์˜ ํ•จ์ˆ˜๋กœ ํ‘œํ˜„๋œ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„์™€์˜ ์ƒ๊ด€์„ฑ์€ Fig.8๊ณผ ๊ฐ™์ด ํ‘œํ˜„๋œ๋‹ค. ์ฆ‰, ๊ฐ•์—ฐ์„ ์˜ ์ค‘๋Ÿ‰๊ฐ์†Œ๋Ÿ‰๊ณผ ์‹œ๊ฐ„์— ๋”ฐ๋ฅธ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ์ด์šฉํ•˜์—ฌ ๋ถ€์‹๊ฐœ์‹œ์‹œ๊ฐ„ ti๋ฅผ ์—ญ์œผ๋กœ ๊ณ„์‚ฐํ•˜๊ณ  ๋ถ€์‹์ด ์‹œ์ž‘๋˜๋Š” ์ˆœ๊ฐ„์ ์ธ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ์—ญ์‚ฐํ•˜์—ฌ Table 2์— ์ •๋ฆฌํ•˜์˜€๊ณ , ํ…๋˜๋ถ€์‹์„ ์œ ๋ฐœํ•˜๋Š” ์ž„๊ณ„ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋Š” Fig.9์™€ ๊ฐ™๋‹ค. ์—ฌ๊ธฐ์„œ, HDPE๋ฅผ ์ ์šฉํ•œ G-H์™€ G-H-C ์‹œํ—˜ํŽธ์€ ์‹œํ—˜์ข…๋ฃŒ ๋•Œ๊นŒ์ง€ ๋ถ€์‹์ด ์ง„ํ–‰๋˜์ง€ ์•Š์€ ๊ฒƒ์œผ๋กœ ๊ฐ„์ฃผํ•˜์—ฌ ๋‘ ์‹œํ—˜์ฒด๋ฅผ ์ œ์™ธํ•˜๊ณ  ํ‰๊ท ์ ์ธ ์ž„๊ณ„ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ์ถ”์ •ํ•œ ๊ฒฐ๊ณผ์ด๋‹ค. ์—ผ์†Œ์ด์˜จ๋งŒ์œผ๋กœ ๋ถ€์‹๋œ ๊ฒƒ๊ณผ ์‚ฐ์†Œ๊นŒ์ง€ ๋ณ‘ํ–‰ํ•˜์—ฌ ๋ถ€์‹๋œ ์‹œํ—˜ํŽธ์˜ ์ถ”์ด๋Š” ๋‹ค์†Œ ์ฐจ์ด๊ฐ€ ์žˆ์—ˆ์œผ๋‚˜ ์ „์ฒด์ ์ธ ์ถ”์ด๋Š” ์œ ์‚ฌํ•˜์˜€๋‹ค.

Fig. 8. Schematic concept to define the relationship between corrosion current density and metal loss

../../Resources/kci/JKCI.2019.31.6.557/fig8.png

Table 2. Corrosion current density vs. metal loss under chloride solution and dissolved oxygen

Item

Specimen

$i_{corr}(t)= at^{3}+bt^{2}+ct$

$t_{i}$

(days)

$i_{corr}$ to corrosion

(vA/cm$^2$)

$a$

$b$

$c$

B

5.8E-3

-5.9E-1

2.1E-1

0.009

0.18

G

0

-2.3E-3

1.5E-1

0.6

0.16

C

3.0E-5

-3.4E-3

1.1E-1

2

0.18

G-C

-1.0E-6

7.0E-5

3.2E-3

33

0.14

G-H

1.0E-6

-1.0E-4

4.6E-3

45

0.02

G-H-C

8.0E-7

-9.0E-5

3.0E-3

42

0.03

Fig. 9. Critical corrosion current density

../../Resources/kci/JKCI.2019.31.6.557/fig9.png

Feliu et al.(1996)์€ 0.10 ยตA/cm$^2$ ์ดํ•˜์˜ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋Š” ๋ฌด์‹œํ•  ๋งŒํ•˜๋‹ค๊ณ  ํ•˜์˜€๋Š”๋ฐ, Broomfield et al.(1994)๋„ ๊ฐ€๋“œ๋ง ์žฅ์น˜๊ฐ€ ๋ถ€์ฐฉ๋œ ์ƒํƒœ์—์„œ ๊ฐ™์€ ์ˆ˜์น˜ ์ดํ•˜๊ฐ€ ์ธก์ •๋˜๋ฉด ๊ธˆ์†์€ ๋ถ€๋™ํƒœ ์ƒํƒœ๋ผ๊ณ  ์ถ”์ •ํ•˜์˜€๋‹ค. ๋ฐ˜๋ฉด, Clear(1989)๋Š” ๊ฐ€๋“œ๋ง ์žฅ์น˜ ์—†์ด ์ธก์ • ์‹œ 0.20 ยตA/cm$^2$ ์ดํ•˜๋ฅผ ๋ถ€๋™ํƒœ ์ƒํƒœ๋กœ ๊ฐ„์ฃผํ•˜์˜€๋‹ค. Bertolini et al.(2013)์€ 2.0 ยตm/year์˜ ๋ถ€์‹์†๋„๋Š” ๋ฌด์‹œํ•  ์ˆ˜ ์žˆ๋‹ค๊ณ  ๋ณด๊ณ ํ•˜์˜€๋Š”๋ฐ ์ด๋ฅผ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋กœ ํ™˜์‚ฐํ•˜๋ฉด 0.20 ยตA/cm$^2$์— ์ƒ์‘ํ•œ๋‹ค. ๋ณธ ์—ฐ๊ตฌ๋Š” ์—ผ์†Œ์ด์˜จ๋งŒ์œผ๋กœ ๋ถ€์‹๋  ๊ฒฝ์šฐ ํ‰๊ท ์ ์œผ๋กœ 0.15 ยตA/cm$^2$, ์—ผ์†Œ์ด์˜จ๊ณผ ์‚ฐ์†Œ์˜ ๋ณ‘ํ–‰ ์ž‘์šฉ์œผ๋กœ ๋ถ€์‹๋œ ๊ฒฝ์šฐ๋Š” 0.17 ยตA/cm$^2$์˜ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„์—์„œ ๋ถ€์‹์ด ์‹œ์ž‘๋˜์—ˆ์œผ๋ฉฐ, ์ด๋Š” ๊ธฐ์กด ์—ฐ๊ตฌ์™€ ์œ ์‚ฌํ•˜๊ฑฐ๋‚˜ ๋‹ค์†Œ ๋†’์€ ์ˆ˜์น˜์ด๋‹ค. ํ–ฅํ›„ ์ด ์ž„๊ณ„์น˜๋Š” ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ์‚ฐ์ •ํ•˜์—ฌ ๋ถ€์‹ ์—ฌ๋ถ€๋ฅผ ์ถ”์ •ํ•  ๋•Œ ํ™œ์šฉ๋  ์ˆ˜ ์žˆ์„ ๊ฒƒ์ด๋‹ค.

4. ๊ฒฐ ๋ก 

1) ์—ผ์ˆ˜๋กœ๋ถ€ํ„ฐ ์–ด๋–ค ๋ณดํ˜ธ๊ณต๋ฒ•๋„ ์ ์šฉํ•˜์ง€ ์•Š์€ ๊ฐ•์—ฐ์„ ์€ ์ด‰์ง„์‹คํ—˜ 2์ฃผ ๋งŒ์— ๋งค์šฐ ๋†’์€ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ๋ณด์˜€์ง€๋งŒ, ๋ถ€์‹๋ฐฉ์ง€ ๊ณต๋ฒ•์„ ์ ์šฉํ•œ ์‹œํ—˜์ฒด๋Š” ๋น„๊ต์  ๊ฒฝ๋ฏธํ•˜์˜€๋‹ค. ๊ทธ๋ฆฌ์Šค ์ฝ”ํŒ… ์‹œํ—˜ํŽธ์€ ์‹œ๊ฐ„์ด ๊ฒฝ๊ณผํ•˜๋ฉด์„œ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๊ฐ€ ์ƒ์Šนํ•˜์˜€์ง€๋งŒ, ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ…๋œ ์‹œํ—˜ํŽธ์€ ์‹œ๊ฐ„์— ๋”ฐ๋ผ ๊ฐ์†Œํ•˜์˜€๋‹ค. ๊ทธ๋Ÿฌ๋‚˜, ์ด๋Š” ์‚ฐ์†Œ ๊ธฐํฌ์˜ ๋ฌผ๋ฆฌ์  ํƒ€๊ฒฉ์— ์˜ํ•œ ๊ทธ๋ฆฌ์Šค ๋„๋ง‰ ์†์ƒ์— ๊ธฐ์ธํ•œ๋‹ค. ๋˜ํ•œ, ๊ณ ๋ฐ€๋„ ํด๋ฆฌ์—ํ‹ธ๋ Œ HDPE ์‰ฌ์Šค๋ฅผ ์ด์šฉํ•œ ์‹œํ—˜ํŽธ์€ ๊ฐ€์žฅ ์šฐ์ˆ˜ํ•œ ๋ฐฉ์‹๋Šฅ๋ ฅ์„ ๋ณด์˜€๋‹ค.

2) ์—ผ์ˆ˜์™€ ์šฉ์กด ์‚ฐ์†Œ์— ์˜ํ•œ ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹์—์„œ๋Š” ๊ทธ๋ฆฌ์Šค๋งŒ์œผ๋กœ ๋„๋ง‰ ์ฒ˜๋ฆฌ๋œ ์‹œํ—˜ํŽธ์—์„œ ์—ผ์ˆ˜์— ์นจ์ง€๋œ ์‹œํ—˜ํŽธ ๋Œ€๋น„ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๊ฐ€ ํฌ๊ฒŒ ์ƒ์Šนํ•˜์˜€๋‹ค. ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ… ๋œ ์‹œํ—˜ํŽธ๋„ ์‹œ๊ฐ„ ๊ฒฝ๊ณผ์— ๋”ฐ๋ผ ๋‹ค์†Œ ๊ฐ์†Œํ•˜์˜€์œผ๋‚˜, ๊ทธ๋ฆฌ์Šค๋ณด๋‹ค๋Š” ์—ผ์†Œ ๋ฐ ์‚ฐ์†Œ์˜ ๋ถ€์‹์— ๋Œ€ํ•˜์—ฌ ์ž˜ ๋ณดํ˜ธํ•˜์˜€๋‹ค. HDPE ์‰ฌ์Šค๋ฅผ ์ด์šฉํ•œ ๊ฒƒ์€ ์ด ์‹œํ—˜์—์„œ๋„ ์šฐ์ˆ˜ํ•œ ๋‚ด๋ถ€์‹ ์„ฑ๋Šฅ์„ ๋ณด์˜€๋‹ค.

3) ๋ถ€์‹์œผ๋กœ ์ธํ•˜์—ฌ ๊ฐ์†Œํ•œ ๊ฐ•์—ฐ์„ ์˜ ์ค‘๋Ÿ‰๊ฐ์†Œ๋Ÿ‰๊ณผ ์‹œ๊ฐ„์˜ ํ•จ์ˆ˜๋กœ ํ‘œํ˜„๋œ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„์™€์˜ ์ƒ๊ด€์„ฑ์„ ํ† ๋Œ€๋กœ ๋ถ€์‹๊ฐœ์‹œ ์ž„๊ณ„ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ์‚ฐ์ •ํ•œ ๊ฒฐ๊ณผ, ์—ผ์†Œ์ด์˜จ๋งŒ์œผ๋กœ ๋ถ€์‹๋  ๊ฒฝ์šฐ ํ‰๊ท  0.15 ยตA/cm$^2$, ์—ผ์†Œ์ด์˜จ๊ณผ ์‚ฐ์†Œ์˜ ๋ณ‘ํ–‰์ž‘์šฉ์œผ๋กœ ๋ถ€์‹๋œ ๊ฒฝ์šฐ๋Š” 0.17 ยตA/cm$^2$ ์ˆ˜์ค€์ด์—ˆ๋‹ค.

4) ๊ฐ•์—ฐ์„ ์˜ ๋ถ€์‹์ „๋ฅ˜๋ฐ€๋„๋ฅผ ํ‰๊ท ํ•˜์—ฌ ๊ตฌํ•œ ๊ฒฐ๊ณผ, ๊ทธ๋ฆฌ์Šค ์ฝ”ํŒ…๋œ ์‹œํ—˜์ฒด๋Š” ๋‹ค๋ฅธ ๊ณต๋ฒ•์— ๋น„๊ตํ•˜์—ฌ ๋‚ด๋ถ€์‹์„ฑ๋Šฅ์ด ๋‹ค์†Œ ๋‚ฎ์•˜๋˜ ๋ฐ˜๋ฉด, ๊ฐ€์žฅ ์šฐ์ˆ˜ํ•œ ๋‚ด๋ถ€์‹์„ฑ๋Šฅ์„ ๋ณด์ธ ๊ฒƒ์€ HDPE ์‰ฌ์Šค๋ฅผ ํ™œ์šฉํ•œ ๊ณต๋ฒ•์œผ๋กœ, HDPE ์‰ฌ์Šค๋ฅผ ์‚ฌ์šฉํ•˜๋ฉด ์ƒ์œ„์— ์‹œ๋ฉ˜ํŠธ ๊ทธ๋ผ์šฐํŒ…์„ ํ•˜์ง€ ์•Š๋”๋ผ๋„ ํ…๋˜์˜ ์šฐ์ˆ˜ํ•œ ๋‚ด๋ถ€์‹์„ฑ์„ ํ™•๋ณดํ•  ์ˆ˜ ์žˆ๋‹ค.

๊ฐ์‚ฌ์˜ ๊ธ€

๋ณธ ์—ฐ๊ตฌ๋Š” ํ•œ๊ตญ์—ฐ๊ตฌ์žฌ๋‹จ๊ณผ ํ•œ๊ตญ์ˆ˜๋ ฅ์›์ž๋ ฅ์˜ ์—ฐ๊ตฌ๋น„ ์ง€์›์œผ๋กœ ์ˆ˜ํ–‰๋˜์—ˆ์Šต๋‹ˆ๋‹ค. (2018R1D1A1B07042819, 2015R1A5 A1037548)

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