• 한국수산과학회지
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• 제48권6호
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• pp.960-968
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• 2015

This study examined the spatiotemporal distribution of demersal fish aggregations in the Northern East China Sea by conducting a trawl survey with hydroacoustic devices. A bottom trawl was used for this survey and fish density was determined from the catch data. Acoustic data were collected at frequencies of 38 and 200 kHz from November to December 2014 and converted into the nautical area scattering coefficient (NASC, $m^2/n{\cdot}mile^2$). In the catch data analysis, the range of catch per unit area by station was $26-8,055kg/km^2$ and for the acoustic data, that of the NASC was $0.45-34.80m^2/n{\cdot}mile^2$. The values were significantly correlated. The combined results of both surveys found that the density was highest at St. 5 ($33^{\circ}$ 10.3', $126^{\circ}$ 23.3') and lowest at St. 8 ($33^{\circ}$ 20.7', $127^{\circ}$ 36.3'). The application of hydroacoustic methods offers a new approach for estimating the biomass of demersal fish aggregations.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2012년도 추계학술대회
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• pp.117-118
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• 2012

수로데이터 기술표준이 S-57에서 S-100으로 변경됨에 따라 국가 해사안전정보 제공기관은 차세대 전자해도 뿐만 아니라 다양한 해사안전정보를 제공할 수 있는 표준화 체계가 마련되었다. S-57 전자해도를 표시하고 항해지원 기능을 제공하는 ECDIS는 S-100 표준의 출현으로 신규 표준에 대한 고려가 요구되며, 이를 통해 S-10X 데이터 및 e-Nav 정보가 운용 가능할 것으로 판단된다. 본 연구에서는 S-100 기반 항해지원시스템 설계를 위해 S-100 표준기술의 운용 메카니즘을 분석하고 이를 기반으로 설계 세부 결과를 수로데이터 로딩 모듈, SENC 표현 모듈, 항해지원 모듈로 구분하여 정리 하였다. 본 시스템의 입력 자료로 예상되는 S-10X 데이터는 차세대 전자해도, 해저지형 그리드 데이터, 전자항해서지 등을 반영 하였다.

• 한국수산과학회지
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• 제54권6호
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• pp.1023-1029
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• 2021

The Japanese common squid Todarodes pacificus is one of the fish species within the total allowable catch (TAC) system which requires further investigation. In this study, the acoustic survey method was used to analyze the distribution of the Japanese common squid Todarodes pacificus across all the seas of South Korea. The sea area within Korea was investigated using the research vessels 20, 21, and 22 of the National Institute of Fisheries Science. The acoustic surveys were carried out from July to September 2019 and February to May 2020. The acoustic systems used in the survey had frequencies of 38 kHz and 120 kHz (EK60, EK80, Simrad, Norway) of the split-beam scientific echosounder. The results showed that, in spring, 277 m²/nmi² was the highest in the east sea area, and the same in the summer season 880 m²/nmi² was the highest in the east sea area. In autumn, the highest nautical area scattering coefficient (NASC) value was observed in the coastal portion of the south sea, and in winter, the NASC values were generally low in all the sea area.

• 수산해양기술연구
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• 제52권1호
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• pp.24-35
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• 2016

An acoustic and trawl pilot survey using a small vessel was conducted in Jinhae bay of the South Sea of South Korea on April 13~14, May 11~13 and June 8~10, 2015. During the survey, acoustic data was collected and bottom trawls were conducted at the same time. First, various noises were eliminated by using the Park method based on the Wang method (Wang et al., 2015; Park et al., 2015), the species compositions and catch rate from each bottom trawl were observed, and spatial distribution of fishery resources in the water column and their nautical area scattering coefficient (NASC) were investigated through acoustic data. During the entire survey period, 12 orders, 33 families and 41 species were caught. The most caught species in April, May and June were Okamejei kenojei, Zoarces gilli and Pholis nebulosa, respectively. Fish schools were observed near the line of net mouth height in April. Numerous weak scatters were presented on the echograms in May and June. Many fish schools appeared in between the water surface and 20 m deep in May. The NASC value from entire water columns was the lowest in April ($35.9m^2/n{\cdot}mile^2$) and highest in June ($1541.3m^2/n{\cdot}mile^2$).

• 한국수산과학회지
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• 제25권1호
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• pp.1-14
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• 1992

국립수산진흥원의 16개년(1973-1988)의 해양 관측 자료와 1989년 11월 6-11일 동안 한국해양대학 실습선으로 관측한 CTD 자료를 사용하여 대한해협 서수도에 존재하는 저층 냉수의 유입 경로를 조사하였다. 대한해협 서수도의 저층 수온은 하계에 가장 낮으며, 해에 따라 변동이 큰 것으로 나타났다. 하계 대한해협 서수도에 저층 냉수가 존재하였던 해의 수온 분포에 의하면, 동해 남서부 해역에 있는 냉수가 울산 남동쪽 10-15마일 떨어진 해역을 거쳐 대한해협 서수도에 유입되며, 이 냉수는 이류하는 동안 그 특성이 다소 변하는 것으로 나타났다.

• 한국수산과학회지
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• 제48권5호
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• pp.798-804
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• 2015

The distributions of demersal fish along the coast of the South Sea, Korea, were estimated from a hydroacoustic survey and bottom trawl catches in April of 2015. Acoustic data were collected at 38 kHz, and converted into the nautical area scattering coefficient (NASC, m²/n·mile²) for 0.1 n∙mile along eight transects during day and nighttime. Various demersal fish species were collected and the dominant species comprised no more than half of the catch. The estimated acoustic density of demersal fish compared well with the cumulative catch weight from bottom trawl catches in daytime, but showed a low correlation at nighttime. The NASC of pelagic fish determined for anchovy was correlated with water temperature. The combined hydroacoustic and trawl method can be used to understand the spatial/temporal structure and estimate the density of demersal fish in coastal areas.

• 한국수산과학회지
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• 제47권5호
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• pp.671-681
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• 2014

The distribution and abundance of coastal fish species in Asan Bay, Korea, were estimated from hydroacoustic survey and net catches. Acoustic data were collected with 38 and 200 kHz from July to October of 2012, and converted to the nautical area scattering coefficient (NASC, $m^2/mile^2$) for $0.25n{\cdot}mile$ along ten transects. Japanese anchovy Engraulis japonicus was the dominant specie in the net catches. The virtual echogram technique was used to distinguish E. japonicus from other species based on the differences in the mean volume backscattering strength (${\Delta}MVBS$) at 38 and 200 kHz. Engraulis japonicus and other fishes are mainly distributed in the center channel and outer part of Asan Bay. E. japonicus tends to move from inner to outer Asan Bay in summer and fall. From NASC data, the target strength and length-weight function of E. japonicus and other fishes were used to estimate the E. japonicus stock at 24.1-93.3 tons, and other fish at 40.6-88.4 tons from July to October 2012. The estimated anchovy biomass compared well with the cumulative catch weight from stow net catches. The hydroacoustic method offers an approach to understanding spatial/temporal structure and estimating the biomass of fish aggregations in coastal areas.

• Journal of Astronomy and Space Sciences
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• 제28권4호
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• pp.319-332
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• 2011

The objectives of this study are to analyze the satellite visibility at the randomly established ground sites, to determine the five optimal ground sites to perform the optical surveillance and tracking of domestic satellites, and to verify the acquisition of the optical observation time sufficient to maintain the precise ephemeris at optimal ground sites that have been already determined. In order to accomplish these objectives, we analyzed the visibility for sun-synchronous orbit satellites, low earth orbit satellites, middle earth orbit satellites and domestic satellites as well as the continuous visibility along with the fictitious satellite ground track, and calculate the effective visibility. For the analysis, we carried out a series of repetitive process using the satellite tool kit simulation software developed by Analytical Graphics Incorporated. The lighting states of the penumbra and direct sun were set as the key constraints of the optical observation. The minimum of the observation satellite elevation angle was set to be 20 degree, whereas the maximum of the sun elevation angle was set to be -10 degree which is within the range of the nautical twilight. To select the candidates for the optimal optical observation, the entire globe was divided into 84 sectors in a constant interval, the visibility characteristics of the individual sectors were analyzed, and 17 ground sites were arbitrarily selected and analyzed further. Finally, five optimal ground sites (Khurel Togoot Observatory, Assy-Turgen Observatory, Tubitak National Observatory, Bisdee Tier Optical Astronomy Observatory, and South Africa Astronomical Observatory) were determined. The total observation period was decided as one year. To examine the seasonal variation, the simulation was performed for the period of three days or less with respect to spring, summer, fall and winter. In conclusion, we decided the optimal ground sites to perform the optical surveillance and tracking of domestic satellites and verified that optical observation time sufficient to maintain the precise ephemeris could be acquired at the determined observatories.

• Ocean and Polar Research
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• 제30권2호
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• pp.181-191
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• 2008

This study aims at assessment of spatio-temporal distribution of demersal fish aggregations near the west coast of Jeju Island using hydroacoustic survey. A 200 kHz split beam transducer attached to a small towed body was used for all acoustic investigations. The received acoustic data were in situ acoustic target strength (TS, dB) for all pings and nautical area scattering coefficient(NASC, $m^2/mile^2$) for 0.1 mile along 12 acoustic transects. Demersal fish aggregations are distributed around the coastal slope having 20 to 30 m depth throughout all seasons. The concentration is higher during the summer season. With regard spatial distribution, higher demersal fish aggregations have been detected near the West coast of Shinchang and especially near Chagwi-do. Pelagic fish aggregations were higher to the south of Chagwi-do during the spring season. Additionally, standing stock of demersal fish aggregations from the NASC data, TS function, and length-weight function of dominant species was estimated as follows: 3.2 ton (CV 21.8%) in December 2006, 17.9 ton (CV 21.6%) in April 2007, 30.8 ton (CV 17.8%) in June 2007, and 22.5 ton (CV 24.2%) in October 2007. The application of hydroacoustic methods offers a new approach to understanding spatiotemporal structure and estimate the biomass of demersal fish aggregations in the coastal area. And the results can be made up limitations of qualitative analysis through net and diving for fisheries resources survey in coastal area.

• 한국수산과학회지
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• 제45권5호
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• pp.486-492
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• 2012

In the late 1970s, the National Fisheries Research & Development Institute (NFRDI) started cetacean research to submit the Korean whale catch record to the International Whaling Commission. This continued until the moratorium on commercial whaling in 1986. The NFRDI resumed cetacean research with a pilot whale sighting survey in 1999. Subsequently, the NFRDI has conducted 53 cetacean sighting surveys within the Korean exclusive economic zone between 2000 and 2010. The surveys took a total of 760 days and cruising for 23,866 nautical miles. The finless porpoise Neophocaena asiaeorientalis was sighted most frequently (735 times), followed by the minke whale Balaenoptera acutorostrata (396 times), the long-beaked common dolphin Delphinus capensis (102 times), and the Pacific white-sided dolphin Lagenorhynchus obliquidens (27 times). Minke whales were distributed in the Yellow Sea and coastal area of the East Sea from spring to fall. Pacific white-sided dolphin sightings were restricted to the middle and upper coastal areas of the East Sea in summer. Common dolphins were sighted from east of the southern coast to the eastern coast of the Korean Peninsula from spring to fall. Finless porpoise occurred in all Korean coastal areas, except the middle and upper eastern coast.