선박 및 수중구조물의 고속, 대형화 및 요구조건 강화의 추세에 따라 유동소음 예측기술의 중요성이 강조되고 있다. 항공, 철도 등의 공력소음 분야에서는 음향상사법을 이용하여 순음 및 광대역 유동소음에 대해 활발히 연구되고 있는 반면 조선해양분야에서는 수중추진기의 날개주파수소음에 대해서만 일부 고려되고 있다. 본 논문에서는 날개면 형상의 주요 유동소음발생 메커니즘 뒷날소음을 고려 가능한 FW-H Formulation 1B를 이용하여 수중추진기 및 선저부가물의 기초요소인 수중익에 대해 광대역소음 예측기법을 연구하였다. 기존의 FW-H Formulation 1B는 공기 중의 압력상관관계 모델에 기반하여 구성되어 있어 매질에 대한 일반성 및 정확도의 한계를 가지므로 수중환경에 대해 일반성을 가지는 벽면변동압력 모델로 확장하는 방법론을 제시하였다. 공기 중 날개면의 소음계측결과와 비교해 벽면변 동압력 모델을 이용할 경우 기존모델의 해석결과 대비 5 dB 이내의 오차로 정확도 관점에서의 유용성을 확인할 수 있었으며 전산유체역 학과 벽면변동압력을 이용한 수중환경의 광대역소음해석 절차를 확립하고 수중익의 광대역소음 예측을 수행하였다.

A scientific and objective sound exposure criterion for underwater sound damage on fish has been required since there has been many disputes between an underwater sound maker and a fish damage receiver. The existing criteria are still incomplete scientifically owing to a degree of variability of underwater sounds, diversity of fish hearing sensitivity and damage types, etc. This study reviews existing studies on a hearing mechanism of fish species, manmade underwater sound characteristics and sound exposure assessment parameters, and recent sound exposure criteria. A governing equation for damage coverage estimation and damage coverage dependency on sound source level, ambient noise and transmission loss are also reviewed and interpreted based on sound exposure environments. The foreign and Korean (National Environmental Dispute Medication Commission) criteria are reviewed and compared based on scientific aspects. In addition, the deficit and limit of Korean criteria are presented. The objective of this study is to give a direction for related researches and legislation of sound exposure criteria on fish.

Jinhae Bay located in the southern of Korean Peninsular is an important spawning area in Korea. By some preliminary studies it was measured several times that adult Pacific codes (Gadus microcephalus) were passed (swimming layer: 15 to 18 m) over a submerged sea tunnel (sea bottom: about 30 m) rather than another immigration route when the Pacific codes were tagged surgically with an acoustic transmitters and released inside of the Bay. There is a possibility that the Pacific codes and the other fishes use the route on the sea tunnel as an immigration route are affected by a human–generated underwater noise around the sea tunnel due to the sea tunnel traffic. On this study the 25–hour measurements of the underwater noise level by water layer were conducted with a hydrophone attached on a portable CTD and an underwater noise level meter during four seasons, and the acoustical characteristics of the underwater noise was analyzed. The mean traffic volume for one hour at the sea tunnel on the spring was shown the largest value of 1,408 [standard deviation (SD): 855] vehicles among four seasons measurement. The next one was ordered on the autumn [1,145 (SD: 764)], winter [947 (SD: 598)] and summer [931 (SD: 558)] vehicles. Small size vehicle was formed 84.3% of the traffic volume, and ultra–small size, medium size, large size and extra–large size of the vehicle were taken possession of 8.7%, 3.2%, 2.0% and 1.8%, respectively. On the daily change of the noise level in vertical during four seasons the noise level of 5 m–layer was shown the highest value of 121.2 (SD: 3.6) dB (re 1 μPa), the next one was 10 m– layer [120.7 (SD: 3.5)], 2 m– and 15 m–layer [120.3 (SD: 3.5 to 3.7)] and 1 m–layer [119.2 (SD: 3.6)] dB (re 1 μPa). In relation with the seasonal change of the noise level the average noise level measured during autumn was shown the highest value of 123.9 (SD: 2.6) dB (re 1 μPa), the next was during summer [121.4 (SD: 3.2)], spring [118.0 (SD: 3.4)] and winter [116.5 (SD: 5.1)] dB (re 1 μPa). In results of eigenray computation when the real bathymetry data (complicate shape of sea bed) was applied the average number of eigenray was 2.68 times (eigenrays: 11.03 rays) higher than those of model bathymetry (flat and slightly sloped sea bottom). When the real bathymetric data toward inside (water depth becomes shallow according to a distance between the source of noise and hydrophone) of the Bay was applied on the eigenrays calculation the number of the eigenray was 1.31 times (eigenrays: 12.49 rays) larger than the real bathymetric data toward outside (water depth becomes deep with respect to the distance). But whenthe model bathymetric data toward inside of the Bay was applied the number of the eigenray was 1.05 times (eigenrays: 4.21 rays) larger than the model bathymetric data toward outside.

This paper describes a prototype mechanical white noise generator has a source level of more than 170.0 dB (re 1µPa at 1 m) at the frequency range of 10 Hz to 100 kHz. The results of performance evaluation of the generator are as follows. The average source level of the generator measured by a step of 15°in horizontal (0 to 360。, 25 points) was 185.2 (SD (standard deviation): 2.3) dB (re 1µPa at 1 m). The maximum and minimum source levels were appeared at the frequency range of 2.5 to 5.0 kHz and around 100 kHz, respectively. The average source levels at 0°, 90。, 180。and 270° were 162.9 (SD: 10.6), 168.4 (SD: 10.0), 162.1 (SD: 9.1) and 166.5 (SD: 11.1) dB (re 1µPa at 1 m). The average source level measured by a step of 30° in vertical was 184.9 (SD: 2.2) dB (re 1µPa at 1 m). The relative maximum variation width of the source levels in horizontal and in vertical measurement were less than 7.0 dB and 1.0 dB, respectively.

본 연구는 잠수기 어업용 수중무선전화기를 설계하는데 있어 최적의 반송 주파수와 송신 신호의 음원 준위를 결정할 목적으로 우리 나라 잠수기 주 조업장의 하나인 거제와 통영 해역의 해양 배경소음과 조업중인 잠수기 어장의 수중 소음에 대하여 검토, 고찰한 결과를 요약하면 다음과 같다. 1. 거제와 통영의 잠수기 어장의 해양 배경 소음을 분석한 결과, 음압 준위는 25∼301kHz 부근에서 가장 낮아 52∼57dB이었고, 주변 통항 선박량과 산업시설이 많은 거제 해역이 통영 해역보다 약 5dB 더 높았다. 2. 거제와 통영의 잠수기 어선의 조업중의 수중소음을 비교하면, 최저 음압준위는 30kHz 부근에서 거제 어장에서는 67dB로서 통영의 62d묘보다 5dB 높은 음압 준위를 나타냈다. 이것은 거제 해역은 잠수기 어선의 규모도 통영 해역의 잠수기 어선보다 약간 크고, 분사기를 사용하여 작업하는데 비해 통영 해역은 잠수기 어선의 크기도 상대적으로 작고, 주 어획 대상물이 달라 분사기를 사용하지 않는 것이 그 원인으로 판단된다. 3. 거제 해역의 패류 채취용 분사기를 사용할 때의 수중 소음의 음압 준위는 102dB었다. 4. 거제 해역의 조업중에 대한 수중 배경 소음을 67dB라 가정할 때, 최대 500m까지 통화하기 위한 송신 신호의 음원 준위는 131dB 정도이다. 그러나, 통영 해역의 잠수기 조업은 분사기를 사용하지 않는 조업으로 이 경우 배경 소음은 약 62dB로서 송신 신호의 음원 준위는 126dB정도이다. 잠수기 조업중이 아닌 경우 즉, 스쿠버 다이버용 수중무선 전화기인 경우에는 배경 소음이 52∼57dB이므로 송신 신호의 음원 준위는 l16∼121dB이면 될 것으로 판단된다.

Most of the underwater noise emitted by small fishing boat are owing to vibration of main engine and generator etc.. This paper describe on the spectrum analysis of underwater noise by engine generating in small fishing boat in order to build up comfortable environment for fisheries man and to reduce ambient noise. The obtained results are summerized as follows:1. When the underwater noise of 10ton class fishing boat measure and the frequency spectrum in varied revolution of engine 750, 900, 1000rpm analyze, the frequency pattern is similar to each other, the faster revolution of engine increase, the higher frequency spectrum level becomes. 2. In comparison of spectrum level of underwater noise between 10ton class and 14ton class fishing boat, the former level is higher than the latter. 3. Frequency spectrum pattern of two 14ton class fishing boat is similar to each other but spectrum level is a little difference, it is suggested to different by fitting condition of engine.

This paper describes to analyze the underwater ambient noise and biological noise of cultivating fishes in the fish farm cages at the seawater Tongyong-kun, KyongNam and lake of Chungju, Chech'on, ChungBuk from 10 to 19 Oct. 1997, in order to find out the characteristics of these noises. The results obtained were as follows; (1) The ambient noise around the fish farm cages at lake of Chungju was 10~200Hz frequency range, 70~105dB spectrum level. The central frequency was 50~70Hz, changing of ambient noise was getting bigger than 10~200Hz in 200Hz~2kKz frequency by wind, water current. (2) The frequency of noise source around the fish farm cage at the seawater of Tongyong-kun was 20~200Hz, spectrum level was 80~100dB while feed factory was working around the fish farm cage. When feed factory did not work, noise source was 10~600Hz frequency range, 70~90dB spectrum level. It was 10dB less than that of while feed factory was working, and then the central frequency was 70Hz. (3) The vessel noise of excursion ship had changed largely at 100dB spectrum level in 10~500Hz frequency band, and the fishing boat had 20Hz~2kHz frequency range. (4) The biological noise in the fish farm cage at lake of Chungju, which was feeding of Cyprinus carpio, 2was 10~30Hz frequency, 70~104dB spectrum level. The central frequency was 75Hz. The biological noises in the fish farm cage at the seawater of Tongyong-kun, which were feeding and swimming noise, had very different spectrum pattern by species, and the frequency band was 10~800Hz.

한국 남해안에서 높게 보고되고 있는 수중소음준위에 대하여 그 소음원을 규명하고자 부산근해의 두 해역에서 파고 1~1.5m의 비교적 조용한 해상 상태일 때 시간별, 깊이별로 10KHz까지 수중소음의 변화를 관측했다. 전체적인 소음준위는 매우 높게 나타났으며, 선박통행이 비교적 뜸했던 A 정점에서는 이들의 편차가 1~2dB 이내로 작은 값을 보였는데 비해 선박 통행이 빈번했던 B 정점에서는 전 주파수대에 걸쳐 그 편차가 각각 4dB와 3dB까지 크게 나타났다. 이것은 그동안 500Hz 이상의 주파수대에서 주 소음원으로 여겨졌던 수면파 외에도 이 해역에서는 선박 소음이 주요 소음원임을 의미하고 있다.

원격측정장치를 제작하여 그 성능을 조사하고, 정치망주변의 수중환경소음과 축양조내의 수중생물소음을 각각 직접.원격측정을 동시에 행하여 그 주파수특성을 비교 분석한 결과를 요약하면 다음과 같다. 1. 원격측정장치의 송신기의 입력신호전압을 100~300 mV로 하였을 때 수중환경소음의 원격측정치와 직접측정치는 50Hz~2KHz의 주파수범위에서 상관계수가 0.97로 가장 잘 일치하였다. 2. 원격측정한 수중환경소음의 음압준위는 송수신기간의 거리에 비례하여 감소하였다. 3. 축양조내의 수중생물소음을 원격측정하여 스펙트럼 분석한 결과 50Hz~2KHz의 주파수범위에서는 원격측정치와 직접측정치가 잘 일치하였으며, 2KHz 이상에서는 일치하지 않았다. 따라서, 원격측정장치의 송수신기의 총합주파수특성을 높이면 여러 가지 해양환경요소의 원격측정과 원력어군탐지기의 제작도 가능함을 알 수 있었다.

Uederwater ambient noise was measured at the set net in the Neung-Po Eay. The environment characteristics depend upon oceanographic conditions of sound propagation and its implication on the source of ambient noise. The results of measurement and analysis were as follows: 1. The frequency of the maximum noise level of two passenger. vessels was around 300 Hz. The spectrum level of the fast vessel (the Air-Ferry) was lower than the little slow vessel (the Olympic) between 50-150 Hz in frequences. 2. The spectrum level of the surface in the playground of the set net was lower than the deeper water till 500 Hz, but over that frequency the level was getting lower as the depth was deep. 3. The spectrum level outside the bag of the set net was greater than the inside between 50 and 700 Hz, but over 1,500 Hz the level inside the bag was higher than the outside. 4. The spectrum level of the outside of the breeding tank was higher than the inside in the daytime. However at night opposite phenomenon occurs.

This paper describes that air noise and underwater noise in the Somjin Estuary are measured and analysed to get the basic data to find out the influence of environment on the underwater. The results obtained are summerized as follows: 1. The spectrum level of air noise in the Somjin Estuary increases until 500Hz, and decreases a little over 2KHz. 2. The spectrum level of underwater noise in the Somjin Estuary increases from 50 Hz to 1 KHz, but it decreases over 1 KHz as the depth is deeper. 3. When the influence of other factors is scarce but the influence of flowing speed is significant, the noise level seems to be higher at speedy layer than at slower layer. 4. The underwater sound level seems to be wider at speedy layer than at slower layer.

북해의 Norway 근해에 있는 외해의 한 점과 Bergen권 입구에 있는 Skossvassen 내만에서 수중환경소음을 측정하여 그 음향 spectrum을 분석한 결과를 요약하면 다음과 같다. 1) Norway 근해에서 측정된 수중환경소음의 주된 주파수대는 500Hz 이하의 저주파였다. 2) Skossvassen 내만에서 측정된 수중환경소음은 10m층에서의 음압이 25m와 50m층에서의 음압보다 약 7dB정도 높았다. 이것은 주된 소음원이 관측점부근을 통항하는 선박이나 육지의 영향을 많이 받는 표층에 있다는 것을 나타낸다. 3) Norway 근해의 외해에서 측정된 수중환경소음은 각 층에서 측정된 spectrum의 형태와 음압준위가 비슷한 현상을 나타내고 있어서 원거리에 있는 소음원의 영향을 많이 받기 때문인 것으로 생각된다.

This paper describes the measurement of the underwater noises produced by the engine vibration around the engine room of stern trawler MIS Sae-Ba-Da(2275GT, 3,600 PS) and pole kner M/S Kwan-Ak-San (243 GT, 1000 PS) while the ship is stopping. The underwater noise pressure level was measured with the underwater level meter of which measuring range is 100 to 200 dB(re bLPa). A and B denotes the maximum pressure level measured at right beneath the bottom of the engine room, while the main engine of the Sae-Ba-Da revoluted at 750 and 500 rpm, respectively. C denotes that of the main engine of the Kwan-Ak-San revoluted at 350 rpm, and D that of the generator of the Sae-Ba-Da revoluted at 720 rpm. Thus A, B, C and D were set for the standard sound source for the experiment. The results obtained are as follows: 1. The noise Pressure level at A, B, C and D were 170.5,165,153 and 158dB, respectively. 2. When the check points distanted vertically 1, 10, 20, 30, 40, 50m from the sound source, the underwater noise presure levels were 170.5, 155, 148, 144 and 138 dB and the directional angle was 116\ulcorner in case of A. 3. The sound level attenuated at the rate of 20dB per 10" meters of the horizontal distance from the sound sources. 4. The frequency distribution of the noise was 100Hz to 10KHz and predominant frequency was 700 to 800Hzminant frequency was 700 to 800Hz

An underwater recording system was designed to measure the sound spectra of the underwater noises produced by fishing gears in operation. Recorded were noi~es from three types of fishing gears: an anchovy set net, three anchovy boat seine net and a stern trawlnet. Acoustic analysis were made using a heterodyne analyzer, a digital frequency analyzer and a level recorder. The no;'e produced by the anchovy set net was found in the high frequency region of the onset of ambient noise spectrum with a slope of - 6 dB/octave. Here the ambient noise spectrum is higher, though similar in shape, than Knudsen spectrum, and is attributed to the breaking action of the coastal wave. Measured noise spectra during the fishing operations of the anchovy boat seine nets are attributed to the background noise of the sea in the presence of the fishing vessels. The frequency distribution of the noise was 20~5, 000 Hz in the case of two steel anchovy boat seiners, and 20-3,000 Hz in the case of the wooden anchovy boat seiner. The predominant frequency range was 250~350 Hz and maximum sound pressure level was 122 dB (re 1μPa) in the case of the steel boat and ] 17 dB in the case of the wooden boat. The noises produced by the trawl fishing gears are remarkably higher than the background noi~e in the presence of the fishing vessel. The frequency distribution of the noi~e was 20-6,300 Hz. The predominant frequency range was 100~200 Hz and maximum sound pressure level was 137 dB ( re 1μPa) . The noise spectra were not so much different from that caused by vibrations of the towing cable and the structure of the ground rope of the trawl net towed in an experimental tank.