• Title/Summary/Keyword: sounder

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Hydro-acoustic survey on fish distribution and aggregated fish at artificial reefs in marine ranching area (음향조사기법을 이용한 수산자원 관리수면의 어류분포 및 인공어초지역의 어군위집조사)

  • Kim, Hyun-Young;Hwang, Bo-Kyu;Lee, Yoo-Won;Shin, Hyeon-Ok;Kwon, Jung-No;Lee, Kyung-Hoon
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.47 no.2
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    • pp.139-145
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    • 2011
  • Hydro-acoustic survey was carried out to estimate a fish distribution at marine ranching area and aggregated fish schools at artificial reef area in Oeyeondo, Korea. The survey system was set up with DGPS system, scientific echo sounder (EK60, Simrad Co.), and ECDIS (Mecys. Co. LTD). A track survey and a random survey was respectively applied to the marine ranching area (474.4ha) and to the artificial reef area (within a radius of 300m). As the result, fish distribution and MVBS values in marine ranching area showed that created fisheries resources didn't come to be abundant yet as to appear fish distribution in all of the area. In the artificial reef area, it was, however, able to detect many fish school signals on the top of and around artificial reefs and to confirm the luring effect of artificial reefs.

Estimating the Abundance of Antarctic Krill Euphausia superba Using a Commercial Trawl Vessel (상업어선의 어군탐지기를 이용한 남극크릴(Euphausia superba) 자원량 추정)

  • Choi, Seok-Gwan;Han, Inwoo;An, Doo-hae;Chung, Sang-deok;Yoon, Eun-A;Lee, Kyounghoon
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.51 no.4
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    • pp.435-443
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    • 2018
  • The Antarctic krill Euphausia superba is important commercially and ecologically as a basic component of the Antarctic Ocean ecosystem. To manage this resource, it is important to determine the distribution and standing of krill in the water layer. Acoustic methods can capture information about the entire water layer quickly. Acoustic surveys were conducted from March 3 to March 14, 2017, using the commercial fishing boat Sejong (7,765 tons). Acoustic systems with a frequency of 38 kHz and a 200 kHz commercial echo sounder (ES70, Simrad, Norway) were used and the acquired data were processed using post processing software. The density and standing of Antarctic krill were determined using the two-frequency difference method, using the characteristics of two frequencies. To compare the frequency difference of krill, the method using the frequency difference according to the krill length, recommended by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) and the values extracted according to the krill length at survey stations where only krill were collected during the study period, were compared. The frequency difference ranges were 3.96-5.91 dB and -3.0~13.8 dB, respectively.

Bathymetric Change of a Sand Mining Site within EEZ, West Sea of Korea (서해 배타적경제수역[EEZ]내 해사채취구역의 지형변화)

  • Kim, Baeck-Oon;Lee, Sang-Ho;Yang, Jae-Sam
    • Journal of the Korean earth science society
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    • v.26 no.8
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    • pp.836-843
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    • 2005
  • Two data sets of repeated hydrographic surveys with a single beam echo-sounder were obtained to investigate morphological changes on a sand mining site within EEZ near the Eocheong Islands, West Sea of Korea. Their accuracies of depth measurement, estimated from the crossover analysis, correspond to the Oder 2 of IHO standards. Bathymetric maps show a feature of 300m wide and 10m deep hollow, whose evolution can be seen in difference grids of the two bathymetric maps. However, data of higher accuracy and resolution enable precise quantification of extracted sand volume. Since this morphological change could affect sedimentary environment as well as benthic ecology, environmental impact assessment based on scientific research data is required for management and sustainable development of limited sand resource.

Analysis of MIMO Channel Characteristics Considering the Building Density in the Urban Area at the 700 MHz Frequency Band (700 MHz 대역에서 도심 지역 건물 밀집도를 고려한 MIMO 채널 특성 분석)

  • Jung, Myoung-Won;Kim, Jong Ho;Chong, Young Jun;Pack, Jeong Ki
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.7
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    • pp.694-700
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    • 2013
  • Urban area is a representative environment of wireless channels in the mobile communication, building density has a different distribution depending on the location. Building density has affect to propagation prediction For this reason, building density is expected to affect to the channel characteristics, we need to analyze it. We measured channel characteristics in urban areas of Jeju island by channel sounder and $4{\times}4$ antenna. Channel characteristics considering the building density were derived based on the measured data in the urban area. In this paper, the measurement data is analyzed and channel characteristics are derived through MIMO Channel measurements at 700 MHz considering the building density in the urban area.

Major Dietary Patterns and Their Associations with Socio-Demographic, Psychological and Physical Factors Among Generally Healthy Korean Middle-Aged Women (건강한 한국 중년 여성에서의 주요 식이패턴과 인구.사회적, 심리적, 신체적 요인 간의 연관성)

  • Lee, Seung-Min;Oh, A-Rim;Ahn, Hong-Seok
    • Korean Journal of Community Nutrition
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    • v.13 no.3
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    • pp.439-452
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    • 2008
  • This study was conducted to identify major dietary patterns of generally healthy Korean middle-aged women and to examine associations of the dietary patterns with socio-demographic, psychological, and physical characteristics. Data were drawn from the 2001 Korean National Health and Nutrition Examination Survey (KNHANES), which is an ongoing national surveillance system. Healthy female subjects aged 40-64 years and provided the health interview examination and food frequency questionnaire (FFQ) data were included. We conducted factor analysis based on daily mean intake frequency of 26 food groups and identified 3 major dietary patterns, healthy, convenient, and alcohol-animal. The healthy pattern was characterized by higher intakes of fish, seafood, poultry, mushroom, seaweed, vegetable, tomato, potato, and fruit, the convenient pattern by processed meat and fish, ramen, noodle and rice cake, sweet snack, egg, bread, and fast food, and the alcohol-animal pattern by alcohol, poultry, meat, and fish. The healthy pattern was significantly related with higher socio-economic status, more stable family structure, healthier mentality, and sounder status of anthropometric and biochemical variables. Those with higher factor scores for the convenience pattern were found to be younger and having higher socio-economic status, higher subjective levels of health, and lower subjective levels of worry on health. Several physical characteristics significantly improved as the levels of the convenience pattern increased. The alcohol-animal pattern was significantly associated with several socio-demographic characteristics including a low education level, a young age, a small family size, and blue-collar jobs. Public health policy makers can utilize the study findings to select prior target populations with higher needs and to tailor dietary behavioral messages to lower chronic disease risks among Korean middle-aged women.

Total Precipitable Water Fields of Typhoons WALT(9407) & FAYE(9503) Derived from TOVS and SSM/I (TOVS 자료로 도출한 태풍(WALT(9407)과 FAYE(9503))에 동반된 총가강수량장)

  • 정효상
    • Korean Journal of Remote Sensing
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    • v.14 no.4
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    • pp.315-324
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    • 1998
  • The total precipitable water fields derived from HIRS(High Resolution Infrared Radiometer Sounder)and MSU(Microwave Sounding Unit) measurements of TOVS and brightness temperature of SSM/I were used to investigate the evolution of moisture fields for the Typhoon WALT(9407) which after landing in Japan it became tropical depression in Korea-Japan Strait, and FAYE(9503) which was the first tropical storm of 1995 to became a typhoon, respectively. The total precipitable water derived from TOVS observations is delineated according to the evolutions of WALT and FAYE movements because total precipitable water fields of TY WALT(9407) and FAYE9\(9503) were largely controlled by horizontal transport of water vapor over the Northwest Pacific Ocean which dominantly plays an important role in maintaining and accelerating their intensities toward Korea and Japan . These fields demonstrated that two major bands, which imply the rain bands, were locally well-organized and similar to the thick convective cloud features over Japan and the Korean peninsula while WALT and FAYE were approaching away and to. But the values of derived TOVS total precipitable water have shown the underestimate of those of SSM/I total comparatively for two typhoons.

Analysis of bed change based on the geometric characteristics of channel cross-sections (유로 단면의 기하학적 특성을 이용한 하상변화량 분석)

  • Ko, Joo Suk;Lee, Kyungsu;Kwak, Sunghyun;Lyu, Siwan
    • Journal of Korea Water Resources Association
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    • v.53 no.12
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    • pp.1097-1107
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    • 2020
  • A methodology has been proposed to understand the spatiotemporal changes of the river topography through the longitudinal change of the geometric characteristics of the cross-sections and the properties related thereto. Three-dimensional spatial information of the riverbed was obtained through the detailed bathymetry survey using an acoustic echo sounder for the reach from Gumi Weir to Chilgok Weir in the Nakdong river. Geometric informations for the reference sections were extracted using the acquired bathymetry survey data. By comparing the geometric properties for the reference sections, it was possible to catch the topographic characteristics and its changes over a reach of the channel. Through comparison with past survey data, it was also possible to quantitatively grasp the amount of change in cross-sectional area and volumetric change of riverbed. It is expected that a quantitative evaluation of river topography changes will be possible by applying the method proposed in this study.

A Study on Improved Inspection Method of the Foundation Scouring and Establishment of 3D Underwater Surface Map (개선된 교량 기초세굴 점검방법 및 3D 하상지도 구축 연구)

  • Choi, Hyun-Chul;Ko, Jun-Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.26 no.5
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    • pp.161-170
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    • 2022
  • The maintenance of bridges installed in rivers is carried out through facility safety inspection and repair & reinforcement procedures according to the results. Many studies have been so far conducted on the safety check of the bridge upperstructure because of the ease of access. However as it is impossible to directly investigate whether the pier foundation installed in the river has been scoured. Management of underwater foundations has remained based on theory. In this study, the scour of the bridge foundation installed in such a river was realized in 3D form by using an echo sounder and VRS. This made it possible to predict the scour pattern through comparison and analysis with the ground height of the riverbed at the time of the bridge installation. Based on these results, if the pier foundation is used as an initial data to determine whether or not local scour is present and to predict long-term scouring, bridge collapse due to foundation scour can be prevented.

The development of buoy type fish finder using LTE communication (LTE 통신을 이용한 부표형 어군탐지기 개발)

  • KANG, Tae-Jong;MIN, Eun-Bi;HEO, Gyeom;SHIN, Hyeon-Ok;HWANG, Doo-Jin
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.58 no.2
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    • pp.141-152
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    • 2022
  • As a method to understand the ecological habits around the artificial reef, various reports such as fishing gear survey, diving, sound survey, underwater CCTV and camera, etc. are reported. Among them, the sound survey method is carried out by installing an acoustic system on the ship and can be investigated regardless of the marine environment such as time constraints and turbidity. Such method, however, takes a lot of manpower and time as the ship travels at a constant speed. Investigations around artificial reefs are being conducted in an artificial way, and a lot of time and labor are consumed as such. Maritime buoys have been operated for various purposes such as route signs, weather observation, marine environment monitoring and defense monitoring for navigation safety in the past, but studies on monitoring systems for ecological habits and distribution of fish using marine buoys are remarkably insufficient. Therefore, this study aims to develop a system that allows users to directly monitor fish group detector data by estimating the distribution of fish groups around artificial reefs and using wireless communication at sea. In order to confirm the suitability of the maritime buoy used in this study, it was operated to compare data using LTE-equipped buoys capable of wireless communication and a data logger-type system buoy. Data transmission of buoys capable of LTE communication was carried out in a 10-minute ON, 10-minute OFF method due to the limitation of the power supply capacity, and data of the data logger-type buoy received full data. We compared and analyzed the data received from the two fish detectors. It is expected that real-time monitoring of the wireless buoy detection device using LTE will be possible through future research.

Seafloor Sediment Classification Using Nakagami Probability Density Function of Acoustic Backscattered Signals (음향후방산란신호의 나카가미 확률밀도함수를 이용한 해저퇴적물 분류)

  • Bok, Tae-Hoon;Paeng, Dong-Guk;Park, Yo-Sup;Kong, Gee-Soo;Park, Soo-Chul
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.3
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    • pp.165-173
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    • 2009
  • The physical properties of a seafloor sediment have been used as a basic data for the ocean survey. Conventional methods such as a coring, a drilling, and a grabbing have been used to explore the physical properties but these methods have a number of shortcomings as it is time consuming, expensive and spatially limited. To overcome these limitations, seafloor sediment classification using acoustic signals has been studied actively. In this paper, we obtained the backscattered signal from the seafloor sediment using an echo sounder which is one kind of seafloor topography equipment. Nakagami probability density function of the backscattered signals from the seafloor sediment was computed and a Nakagami parameter was compared with the physical properties of the seafloor sediment. We have confirmed that Nakagami parameter, m is correlated with the physical properties of a seafloor sediment. This study will be utilized as a basic data of the seafloor sediment research.