• 수산해양기술연구
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• 제34권3호
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• pp.259-273
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• 1998

The hydroacoustic surveys to provide the essential information for the assessment, management and utilization of fishery resources in the southern waters of Korea were carried out during five research cruises between October 1996 and October 1997 by the training ship KAYA of Pukyong National University. These hydroacoustic investigations were designed to obtain more precise estimates of the geographic distribution, absolute abundance and biological characteristics of the fishery resources, and the vertically integrated densities of fish in terms of volume backscattering strength(SV) by survey region and depth bins, such as the entire water column and the 0~ 10 m from bottom fraction, were measured separately. Hydroacoustic data were collected by using a Simrad EK 500 Scientific echo sounder operating at two frequencies of 38kHz and 120kHz and the data stored in field were later processed on a HP PC using a Simrad EP 500 echo integration and target strength analysis system. The biological compositions of echo signal were identified and sampled using a demersal trawl during daylight hours. The mean target strength to scale the echo integration data for hydroacoustic surveys was derived from the relationship between the SV and the weight of trawl catch per unit volume of the water column sampled by demersal trawls. The results obtained can be summarized as follow : 1. The mean volume backscattering strength for the entire water column in the southern waters of Korea between 1996 and 1997 were -67.2 dB and -70.9 dB at two frequencies of 38 kHz and 120 kHz , respectively, and for the bottom layer of the 0-10 m from bottom friction were -68.8 dB, -70.2 dB, respectively. That is, the volume backscattering strength for the entire water column at low frequency was higher than that at high frequency. 2. The relationship between the mean backscattering strength (〈SV〉, dB) for the depth strata of trawl hauls and the weight (C, kg/m3) per cubic meter of the catch sampled by bottom trawling in the southern waters of Korea in January and July 1997 were expressed by the following equations: 38 kHz : 〈SV〉= -28.2 + 10 log(C), 120 kHz : 〈SV〉= -32.4 + 10 log(C). The mean weight -normalized target strengths derived from these equitions were -28.2 dB/ kg, -32.4 dB/ kg at 38 kHz and 120 kHz , respectively. That is, the mean weight -normalized target strength at 38 kHz was 4.2 dB higher than that at 120 kHz. 3. The distribution density of fish in terms of biomass per unit volume in the southern waters of Korea were estimated to be 125.9 $\times$ 10-6 kg/m3 and 141.3 $\times$ 10-6 kg/m3 at 38 kHz and 120 kHz , respectively.

• 한국수산과학회지
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• 제36권5호
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• pp.541-548
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• 2003

Species identification in hydroacoustic survey is one of the key requirements to estimate biomass of organism and to understand the structure of zooplankton community. Feasibility of species identification using two frequencies (38 and 120 kHz) was investigated on the basis of mean volume backscattering strength difference (MVBS). Virtual echogram technique was applied to two frequencies data sets that obtained from surveys in the Antarctic Ocean and Yellow Sea. Virtual echogram method using MVBS revealed the possibility of species identification, which species identification relying on visual scrutiny of single frequency acoustic data resulted in significant errors in biomass estimation. Through noise cancellation using MVBS, much of the acoustic noise caused by acoustic instruments could be removed in new virtual echogram, and the biomass estimation and data quality was improved.

• 수산해양기술연구
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• 제26권1호
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• pp.20-25
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• 1990

동지나해의 초음파산란층에 관한 기초적 연구로서 어군탐지기에 의해 탐지한 어군의 체적산란강도의 연직분포와 수온의 연직분포를 상호 비교\ulcorner검토하고, 또 트로올조업에 의한 어획시험을 행한 결과를 요약하면 다음과 같다. (1) 조사해역에서 표층에 가장 인접하여 형성된 수온약층의 수심구간은 8m~12m였고, 이 수온약층의 상\ulcorner하한에 대한 수온차는 8.6$^{\circ}C$였다. (2) 수온약층이 형성된 해역에 있어서 야간의 경우, 어군분포는 수온약층 상부의 혼합층에서 군집도가 가장 높았으나, 주간의 경우에는 수온약층에 관계없이 해저부근에서 어군의 군집도가 매우 높았다. (3) 본 조사에서 탐지한 어군의 각 수심층에 대한 평균체적산란강도의 최대치는 -49.3 dB~-48.0 dB 범위였다. (4) 주간에 해저부근에서 탐지한 어군의 평균체적산란강도의 최대치는 -48.6 dB로서, 이때 저층 트로올에 의해 어획된 어획물은 주로 게(Ovalipes punctatus)와 오징어(Photololigo edulis f. budo)였고, 이밖에도 약간의 쥐치(Thamnaconus modestus), 칼치(Trichiurus lepturus), 새우(Metanephrops thomsoni) 등이 어획되었다.

• 수산해양기술연구
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• 제50권4호
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• pp.551-555
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• 2014

ADCPs have been widely used to estimate the dynamic characteristics and biomass of sound scattering layers (SSLs), and swimming speed of fish schools for analyzing SSLs spatial distribution and/or various behavior patterns. This result showed that the verification of the mean volume backscattering strength (MVBS or averaged SV, dB) acquired by the ADCP would be necessary for a quantitative analysis on the spatial distribution and the biomass estimation of the SSLs or fish school when ADCP is used for estimating their biomass. In addition, the calibrated sphere method was used to verify values of each MVBS obtained from 4 beams of ADCP (153.6 kHz) on the base of 3 frequencies (38, 120, 200 kHz) of Scientific echo sounder's split beam system. Then, the measured SV values were compared and analyzed in its Target Strength (TS, dB) values estimated by a theoretical acoustic scattering model.

• 수산해양기술연구
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• 제32권1호
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• pp.16-23
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• 1996

Spatial distribution characteristics, volume backscattering strength and species composition of midwater trawling catch was analyzed biological and acoustical characteristics of anchovy shoal, using a high resolution echo - sounder at the south region of East sea of Korea. 1) In the survey site A of Lat.35$^{\circ}$55'N, Long.129$^{\circ}$45'E, the anchovy shoal of small to middle size with the horizontal range of 10~25m and large size with the horizontal range of 40~50m were distributed together. However in the survey site B of Lat.35$^{\circ}$38'N, Long.129$^{\circ}$40'E, the anchovy shoal was observed to be mainly small size which about 78% of the detected shoal. Another was that the anchovy shoal with the vertical range of 2~8m occupied about 68.6% in the survey site A and that of 6~12m occupied about 42.5% in the survey site B. The mainly the site A and B were found to be 10~50m super (2), 64.5% and 20~80m super (2), 66%, respectively. 2) The volume backscattering strength in the site A and B were observed to be -44.0~ -28.0dB, respectively. In the site A, the backscattering strength of -40.0~ -30.0dB was analyzed about 41.4%. 3) Most of total anchovy shoal was concentrated in the water layer of 50~100m in depth with 15.3~18.5$^{\circ}C$, 34.0~34.3$\textperthousand$ in the survey site A and 14.2~16.4$^{\circ}C$, 34.1~34.2$\textperthousand$ in the survey site B. 4) Mean total length(TL) and body weight(BW) of anchovy in the survey site A were 9.9cm and 4.4g respectively, with TL-BW relationship of BW=0.0007T$L^3.65$super (3.85). In site B, mean total length(TL) and body weight(BW) were 11.2cm and 8.7g, with TL-BW relationship of BW=0.0023T$L^3.36$.

• 수산해양기술연구
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• 제26권2호
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• pp.143-150
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• 1990

동지나해의 어업자원량을 정량적으로 평가하기 위한 시도로서, 부산수산대학교와 일본 북해도대학이 공동으로 실시한 제1차 동지나해의 저서어족자원조사중에서 계량어군탐지기를 이용하여 수집한 각종의 기초자료를 분석, 검토한 결과를 요약하면 다음과 같다. 1. 동지나해의 24회 조사 Line에서 저층 Trawl에 의해 어획된 어종수는 총 96어종이고, 1시간 예망당 평균어획량은 58.8kg/hour이었다. 2. 저층 Trawl을 행한 수탐층(약 4.5m)에 분포하는 어군의 평균체적산란강도는 25KHz와 100KHz에서 각각 -63.9dB, -67.3dB로서 저주파수의 경우가 고주파수보다 약 3.4dB 더 높았다. 3. 전수탐층(송수파기과 해저간)에 분포하는 어군의 평균체적산란강도는 25KHz와 100KHz에서 각각 -61.9dB, -67.0dB로서 역시 저주파수의 경우가 고주파수보다 약 1.5dB 더 높았다. 4. 저층 Trawl을 행한 수탐층에 분포하는 어군의 평균체적산란강도(SV, dB)와 이 때 어획된 전위제적당의 평균어획량(kg)으로부터 추정한 kg당의 평균반사강도는 25KHz와 100KHz에서 각각 -23.6dB/kg, -26.3dB/kg로서 저주파수의 경우가 고주파수보다 약 2.7dB/kg 더 컸다.

• 수산해양기술연구
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• 제46권4호
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• pp.449-457
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• 2010

This study shows that the vertical migration speed of sound scattering layers (SSLs), which is distributed in near Funka Bay, were measured by 3D velocity components acquired from a bottom moorng ADCP. While the bottom mooring type has a problem to measure the velocity vectors of sound scattering layer distributed near to surface, both the continuous vertical migration patterns and variability of backscatterers were routinely investigated as well. In addition, the velocity vectors were compared with the vertical migration velocity estimated from echograms of Mean Volume Backscattering Strength, and estimated to produce observational bias due to SSLs which is composed of backscatterers such as euphausiids, nekton, and fishes have swimming ability.

• 수산해양기술연구
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• 제32권3호
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• pp.266-272
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• 1996

The distribution and abundance of fish in the Cheju southeastern area was studied by the combined hydroacoustic and bottom trawl surveys in April 1994 and in July 1995, respectively. The main purpose of these investigations was to provide the basic data for this management and the biomass estimation of commercially important demersal fish stocks in this area. The hydroacoustic surveys were performed by using a 50 kHz scientific echo sounder system with a microcomputer-based echo integrator. Acoustical measurements of fish abundance and distribution were conducted along the cruise tracks of research vessel and during all trawl hauls by continuous echo sounding. The average weight-normalized target strength for demersal fish aggregations was derived from the relationship between the mean volume backscattering strength for the depth strata of trawl hauls and the weight per cubic meter of trawl catches. The geographical distribution of fish stocks in the 1994 survey area was investigated in relation to oceanographic conditions. The results obtained can be summarized as follows: 1. From the 1994 and 1995 survey data, the relationship between the mean volume backscattering strength (, dB) for the depth strata of trawl hauls and the weight (W, kg/$m^3$) per cubic meter of trawl catches was expressed by the following equation = - 32.8+ lOlog(W) The average weighted-target strength value at 50 kHz derived from this equation was .. 32.8 dB/kg. 2. In 1994 and 1995, both surveys showed a trend of decreasing fish abundance toward the southern area of the Cheju Island with high densities offish along the west coast ofth.e Tsushima Island. The highest demersal concentrations in the southern area of the CheJu Island appeared in bottom waters colder than $12^{\circ}C.$. . 3. From the results of combined bottom trawl and hydroacoustic surveys, the estunated fish densities in the southeastern area of the Cheju Island were 1.5488 x $10^-4$kg/$m^3$ in the 1994 surveyand 1.9498 x $10^-4$kg/$m^3$ in the 1995 survey, respectively.

• 한국수산과학회지
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• 제36권6호
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• pp.749-756
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• 2003

Hydroacoustic and open-closing zooplankton net survey were conducted to understand the characteristics of the sound scattering layer (SSL) and to estimate the density of an euphausiid (Euphausia pacifica) in the SSL, in the northwestern part of the East China Sea. The survey was carried out during July 6-9 2002 at 8 sampling stations for zooplankton. The virtual echogram technique was used to identify E. pacifica from all acoustic scatters. Mean volume backscattering strength difference $(MVBS_{120kHz-38kHz})$ and target strength equation for E. pacifica were derived from the Distorted-wave Born Approximation (DWBA) model. Although vertical migration of the SSL is similar to the general pattern, dispersion at night shows some differences. Estimated mean density using acoustic data ranged from $20.4-221.4\;mg/m^3$ over the whole depth, and $87.1-553.5\;mg/m^3$ in the SSL. The density using the zooplankton net ranged from $0.2-362.4\;mg/m^3$ and was not related to net deploying method. The results from the acoustic and net survey suggest that E. pacifica might be an important zooplankton community in the northwestern part of the East China Sea.

• 수산해양기술연구
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• 제27권1호
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• pp.13-20
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• 1991

어군의 분포밀도와 초음파산란강도의 관계를 검토하기 위하여, 50kHz의 주파수에서 net cage (농망)에 분포밀도가 기지인 어군을 수용하고, 어군밀도의 변화에 기인하는 echo energy의 변동을 고찰하고, 또 cage 실험에 의해 추정한 어체의 평균적인 반사강도와 개개의 어체를 대상으로 구한 평균반사강도를 상호 비교, 검토한 결과를 요약하면 다음과 같다. 1. cage 실험에 의한 붕어의 평균반사강도는 -41.9dB로서, 이 값은 현장에서 개개의 붕어(마취어, 평균체장 19.1cm)를 대상으로 측정한 평균반사강도 -42.6dB보다 0.7dB 더 컸다. 2. cage내에 수용한 어군의 분포밀도가 증가함에 따라, 어군에 의한 평균체적산란강도는 직선적으로 증가하는 경향을 나타내었다. 즉, 어군밀도가 7, 13, 20, 26, 39, 52, 66 마리/m 상(3)였을 때, 각각의 어군에 의한 평균체적산란강도는 -33.0, -28.9, -27.6, -24.3, -25.1, -23.6, -22.1dB이었다. 3. 어군밀도 $\rho(마리/m$ 상(3))와 평균체적산란강도 (dB)와의 사이에는 다음의 관계식이 성립하였다. =-41.9+11.0 $Log(\rho),$ r=0.97 이 식에 회귀직선의 기울기 11은 이론적인 값 10에 거의 근사하였다.