한수지 49(6), 856-861, 2016 Original Article Korean J Fish Aquat Sci 49(6),856-861,2016 음향산란층의식별을위한에코그램분석방법의비교 최석관 윤은아 1 * 한인우 1 오우석 1 국립수산과학원원양자원과, 1 전남대학교수산과학과 Comparison of Echogram Analysis Methods for Evaluating the Sound-scattering Layer Seok-Gwan Choi, Eun-A Yoon 1 *, Inwoo Han 1 and Wooseok Oh 1 Distant Water Fisheries Resources Research Division, National Institute of Fisheries Science, Busan 46083, Korea 1 Department of Fisheries Science, Chonnam National University, Yeosu 59626, Korea This study compared the density of fish determined using three different echogram methods: the frequency-difference, time variable, and threshold modification methods. An acoustic survey was conducted off the coast of Jeju Island after sunset. Data at 38 and 120 khz frequencies were collected using a commercial fishing vessel. As a reference point, the value of MVBS 120-38kHz that distinguished fish from zooplankton using the 38 and 120 khz frequencies was set at < 2 db. The estimated density of fish along the survey line was 0.1-30.4, 0.1-64.3, and 0.1-51.7 m 2 / nmi 2 using the frequency difference, time variable threshold, and threshold modification methods, respectively. The results of this study constitute basic research for estimating fish densities. Key words: Acoustic survey, Frequency difference method, Time variable threshold method, Threshold modification method 서론,,.,. (Kang et al., 2008; Hwang et al., 2004; Lee et al., 2015). (echo counting) (echo integration).,.. (Simmonds and MacLennan, 2005)..,. (Hone and Jeck, 1999), 2 (Miyashita et al., 1997; Kang, 2002; Kloser et al., 2002; McKelvey and Wilson, 2006; Kim et al., 2013; Lee et al., 2014)., (Lee et al., 2012; Hwang et al., 2015). (threshold modification), Kang et al. (2012). http://dx.doi.org/10.5657/kfas.2016.0856 Korean J Fish Aquat Sci 49(6) 856-861, December 2016 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial Licens (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Received 15 November 2016; Revised 21 November 2016; Accepted 21 November 2016 *Corresponding author: Tel: +82. 61. 659. 7126 Fax: +82. 61. 659. 7129 E-mail address: euna7979@nate.com Copyright 2016 The Korean Society of Fisheries and Aquatic Science 856 pissn:0374-8111, eissn:2287-8815
음향산란층의식별을위한에코그램분석방법비교 857 38 120 khz 2,,. 음향자료수집 재료및방법. split beam 38 khz 120 khz (EK60, Simrad), 1 m. 38 120 khz 1 ping/s, 0.512 ms, 6-7 DGPS. 음향자료분석 (Echoview V 4.7, Myriax). 150 m,., De Robertis and Higginbottom (2007) Wang et al. (2015). Fig. 1. TVT (Time varied threshold) raw data. data range bitmap (Volume Backscattering Strength, SV), SV mask (De Robertis and Higginbottom, 2007)., data range bitmap,. erosion filter 3 3, erosion filter 999 db.,. dilation filter 5 5 7 7. dilation filter 7 7 data range bitmap SV mask. median 7 7 select mask median 7 7 SV Fig. 1. Flow diagram for noise removal using acoustic analyze software algorithms. data range bitmap, (Wang et al., 2015). Fig. 1 (frequency difference method), (time variable threshold method), (threshold modification method) 3. 3. 38 khz 120 khz (Mean Volume Backscattering Strength, MVBS). 5 ping 1 m. data range bitmap 38 khz mask, 38 khz. (Fig. 2). (Kang, 2012). dilation filter 7 7 (Fig. 3).. 3 raw SV 80~ 30 db
858 최석관ㆍ윤은아ㆍ한인우ㆍ오우석 Fig. 2. Data process flow for discriminating fish using db difference method at 38 and 120 khz.,, TVT 60~-30 db. 0.5 n.mile EDSU (Elementary Distance Sampling Unit) (Nautical Area Scattering Coefficient, NASC, m 2 /n.mile 2 ). 통계분석 3, Fig. 3. Data process flow for discriminating fish using TVT method at 38 khz (Kang, 2012)., (SPSS ver. 21.0, IBM) t-test. 결과및고찰 Fig. 4 38 120 khz raw. Fig. 4 38 120 khz, 120 khz. De Robertis and Higginbottom (2007) Wang et al. (2015) Fig. 4. Comparison of noise removal and raw echograms.
음향산란층의식별을위한에코그램분석방법비교 859 Fig. 5. The db-difference of section of only zooplankton and mixed zooplankton and fish using 38 and 120 khz..,,.,. Park et al. (2015) Lee et al. (2015), SV 1 db..,. Fig. 5 120 khz 38 khz Fig. 6. Range of db difference to identify zooplankton and fish.. 0-28 db, 10 db
860 최석관ㆍ윤은아ㆍ한인우ㆍ오우석 Fig. 7. Exampled of echograms to identify zooplankton and fish using MVBS method. Fig. 8. Correlation relationship of mean NASC (m 2 /nmi 2 ) by transect lines using frequency difference method, time variable threshold method, and threshold modification method.. 14~18 db, 2 db 10 db. Fig. 6. MVBS 120-38kHz 2 db., MVBS 120-38kHz <2 db, 38 khz (Fig. 6). Fig. 7,,.,, Fig. 8. 0.1-30.4 m 2 /nmi 2, 0.1-64.3 m 2 /nmi 2, 0.1-51.7 m 2 /nmi 2. T-, 0.230 (P>0.05), 0.232 (P>0.05), 0.999 (P<0.05). SV SV (Target strength, TS). SV TS, TS SV,
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