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박중희 한국수산학회 1977 한국수산과학회지 Vol.10 No.4
1976년 8월 16일(북위 34°27'30˝ 동경 128°23'15")과 1977년 7일 28일(북위 34°47' 동경 128°53')에 관악산호의 선박소음이 r.p.m에 따라 항해시와 정선시 (기관의 공회선)의 소음압이 海中에 분포하는 것을 조사 연구한 결과를 요약하면 다음과 같다. 1. 기판의 r.p.m.과 음압관계 r.p.m.과 음압의 증가비는 100 : 1이었으며 r.p.m. 600에서 104㏈로 peak를 이루었다. 2. 外舷周邊의 海中音壓分布 A. 정선시의 기관소음압 100, 102, 103,104,104 ㏈일때 관측점 No.1에서 69, 70, 72, 74, 75 ㏈ No.3은 No. 1에 비해 2∼3 ㏈ 증가해 peak를 이루었고 No.5는 No.3에 비해 10∼15 ㏈씩 감쇠되었다. 기관 소음압이 최대 일때 관측점 No.1∼No.5에서의 음압이 투과된 백분율은 약 78,79,80,73,70% 였다. B. 항해시의 선박수중소음압 정선시와 같은 기관회전 조건하에서 No. 2에서 69,72,75,77,78 ㏈로 peak를 이루었고 No. 1보다 2∼3㏈씩 증가했으며 No.5에서는 7∼10 ㏈씩 감쇠 되었다. 기관 최고소음압에 대한 No. 1∼No.5에서의 음압투과 백분율은 약 78,81,79,77,71% 였다. 3. 항해시와 정선시의 外舷海中 음압 peak점에서의 음압을 비교하면 항해시가 1 ㏈ 높았다. 4. 선박이 멀어질때 0 m(관측점 통과시)에서 67 ㏈, 1,400 m에서 55 ㏈였다. 5. 선박이 가까워질때 거리 0 m에서 72 ㏈, 1,400 m에서 57 ㏈로서 멀어질때와 비교하면 0 m에서 5 ㏈, 600 m에서 2 pB씩 증가한 도플러 효과가 일어남을 알 수 있다. 6. r.p.m.을 600으로 하여놓고 스크류를 돌리지 않고 기관만 공회전 시킬때 수평거리 20 m인 곳의 No.7에서 수심 10 m마다 50 m까지의 음압은 68,75,62,59,55,51 ㏈였다. The noise pressure scattered underwater on account of the engine revolution of a pole and liner, Kwan-Ak-San(G. T. 234. 96), was measured at the locations of Lat. 34˚47'N, Long. 128˚53'E on the 16th of August 1976 and Lat. 34˚27'N, Long. 128˚23'E on the 28th of July, 1977. The noise pressure passed through each observation point (Nos. 1 to 5), which was established at every 10 m distance at circumference of outside hull was recorded when the vessel was cruising and drifted. In case of drifting, the revolution of engine was fixed at 600 r. p. m. and the noise was recorded at every 10 m distance apart from observation point No. 3 in both horizontal and vertical directions with 90˚ toward the stern-bow line. In case of cruising, the engine was kept in a full speed at 700 r. p. m. and the sounds passed through underwater in 1 m depth were also recorded while the vessel moved back and forth. The noise pressure was analyzed with sound level meter (Bruel & Kjar 2205, measuring range 37140 ㏈) at the anechoic chamber in the Institute of Marine Science, National Fisheries University of Busan. The frequency and sound waves of the noise were analyzed in the Laboratory of Navigation Instrument. From the results, the noise pressure was closely related to the engine revolution showing that the noise pressure marked 100㏈ when 400 r. p. m. and increase of 100 r. p. m. resulted in 1㏈ increase in noise pressure and the maximum appeared at 600 r. p. m. (Fig. 5). When the engine revolution was fixed at 700 r. p. m., the noise pressures passed through each observation point (Nos. 1 to 5) placed at circumference of out side hull were 75, 78, 76, 74 and 68 ㏈, the highest at No. 2, in case of keeping under way while 75, 76, 77, 70 and 67 ㏈, the highest at No. 3 in case of drifting respectively (Fig. 5). When the vessel plyed 1, 400 m distance at 700 r. p. m. , the noise pressure were 67 ㏈ at the point 0 m, 64 ㏈ at 600 m and 56 ㏈ at 1, 400 m on forward while 72 at 0 m, 66 at 600 m and 57 dB at 1, 400 m on backward respectively indicating the Doppler effects 5 ㏈ at 0 m and 3 ㏈ at 200 m (Fig. 6). The noise pressures passed through the points apart 1, 10, 20, 30, 40 and 50 m depth underwater from the observation point No. 7 (horizontal distance 20 m from the point No. 3) were 68, 75, 62, 59, 55 and 51 ㏈ respectively as the vessel was being drifted maintaining the engine revolution at 600 r.p.m. (Fig. 8-B) whereas the noise pressures at the observation points Nos. 6, 7, 8, 9 and 10 of 10 m depth underwater were 64, 75, 55, 58, 58 and 52 ㏈ respectively (Fig. 8-A).