• 수산해양기술연구
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• 제36권2호
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• pp.96-104
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• 2000

본 연구에서는 저자 등이 개발한 인공해저를 대상으로 어류의 위집행동 및 분포구조를 잠수관찰 및 어군탐지기를 이용하여 조사하였다. 인공해저와 같은 해양구조물 주변에서의 군집구조를 파악하는 것은 인공어초의 위집기구 연구에 중요한 사항이다. 연구에서 얻어진 결과를 요약하면 다음과 같다. 1. 잠수관찰에 의하면 어류의 분포층은 인공해저의 구조와 밀접한 관계를 가지고 있어, 표층 해저면에서는 회유성 어종인 고등어, 전갱이가 군을 형성하여 일시적으로 위집되었다. 한편, 중층 시험 어초 부근에는 정착성 어종인 돌돔, 붉바리, 돔감펭볼락 등이 군을 형성 장시간 체류하는 것이 관찰되어, 이들 어류는 인공어초를 먹이장소 또는 휴식공간으로 긴밀하게 이용하고 있다고 판단되었다. 2. 어군탐지기를 사용하여 인공해저 주변을 24시간 항주조사 한 결과, 어류의 행동생태는 일출몰 시각의 전후로 변화하는 것을 알 수 있었다. 주간에 군을 형성하여 인공해저의 중$.$저층 부근에서 유영하던 어군에코는 야간에는 분산형태로 표층부근에 폭 넓게 산재하고 있어, 어군의 일주행동이 분명하게 밝혀졌다.

• 대한원격탐사학회지
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• 제36권2_1호
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• pp.103-119
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• 2020

최근 기후변화와 4대강 살리기 사업으로 인위적으로 조성된 하천의 급속한 재퇴적 및 침식이 의심스러운 상황이다. 이에 따라 최근 하천법을 개정하여 하상변동조사를 정기적으로 실시해야 한다고 규정하였다. 하지만 하상 조사의 공간적 범위 및 밀도가 대폭 증가하고 조사 간격은 줄어드는 추세에 반해 기술적인 한계가 존재하여, 국가기관 등에서 하상 조사 효율화를 위해 혁신적인 하상조사 기술 개발에 관심을 보이고 있다. 하상 조사의 핵심은 다양한 하천 조건에서 하천의 수심을 측정하는 것에 있으며, 일반적인 지상의 지형측량에 비해 수중에서의 직접 조사는 상대적으로 많은 위험과 시간, 비용을 수반한다. 이에 전통적인 기술의 한계를 극복하고자, 해양 수심측량에 주로 활용되어 온 음향측심기(Echo-sounder)를 하천에 적용하였지만, 여러 기술적 한계로 여전히 광범위한 영역에 대한 주기적인 조사에 어려움을 겪고 있는 실정이다. 이에 원격탐사를 활용한 기법이 그 대안으로 각광받고 있으며, 특히 분광특성을 활용한 수심 측정의 가능성을 보이고 있다. 본 연구에서는 분광특성 중 반사도를 활용하여 수심을 측정할 수 있는 기술을 개발하고 이를 검토하고자 한다. 본 연구에서 제시한 기법을 적용한 결과, 약 0.95 m이내에 해당하는 수심 범위에서 실제 측정된 수심과 0.986, 0.053 m에 해당하는 상관성과 오차를 나타냄을 확인하였다. 향후 본 연구를 드론에 탑재된 초분광 센서에 접목할 경우, 공간적인 수심 측정에 가능할 것으로 사료되며, 광범위한 영역의 주기적인 하상변동조사에 큰 기여를 할 것으로 판단된다.

• 한국수자원학회논문집
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• 제53권12호
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• pp.1097-1107
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• 2020

본 연구에서는 하도단면의 기하학적 특성과 그에 관한 특성값들의 종방향 변화를 통해 하천지형의 시·공간적 변화양상을 파악하기 위한 방법론을 제안하고자 한다. 이를 위해 낙동강 구미보 ~ 칠곡보 구간에 대한 음향측심기를 이용한 상세 수심측량을 통해 하상에 대한 3차원 공간정보를 취득하였다. 취득된 자료를 이용하여 기준단면에 대한 기하학적 정보를 추출하였다. 추출된 하천단면의 기하특성치들을 비교함으로써 특정 하도구간에서의 지형 특징을 파악할 수 있었다. 과거 측량성과와의 비교를 통해 단면변화량과 체적하상변동량을 정량적으로 파악할 수 있었다. 향후 본 연구에서 제안한 방법의 다양한 하천구간에서 대한 적용을 통해 하천지형변화에 대한 정량적 평가방법을 제시할 것으로 기대하는 바이다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2010년 춘계학술발표회 논문집
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• pp.143-144
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• 2010

현재의 수심측량은 고무보트를 타고 사람이 직접 측량하거나 측량선을 이용하여 목표지점을 측정하는 방법 등으로 이루어지고 있다. 기존 측량방법은 환경조건의 제약이 많으며 이와 더불어 다수의 필요인원과 경비의 과다소요 뿐만 아니라 시간적 낭비가 많이 발생하는 비효율적 작업의 형태를 갖추고 있다. 따라서 환경적 제약을 적게 받으면서 적은 인원과 비용으로 단시간 측량이 가능하며 높은 측량 성과를 얻을 수 있는 차세대 수심측량시스템의 필요성이 증가하고 있다. 본 연구는 수심측량의 자동화를 위한 시스템 개발의 기초적 연구로서 유인측량과 무인측량의 각각의 단점을 보완하고 장점을 살리면서 기존측량에 비해 효율성 및 경제성을 높이는 동시에 정밀한 측정데이터를 취득 할 수 있도록 하는 것이다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.187-193
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• 2021

In order to solve the problem of false terrains caused by environmental interferences and tunneling effect in the conventional multi-beam seafloor terrain detection, this paper proposed a seafloor topography detection method based on fast two-dimensional (2D) Censored Mean Level Detector-statistics Constant False Alarm Rate (CMLD-CFAR) method. The proposed method uses s cross-sliding window. The target occlusion phenomenon that occurs in multi-target environments can be eliminated by censoring some of the large cells of the reference cells, while the remaining reference cells are used to calculate the local threshold. The conventional 2D CMLD-CFAR methods need to estimate the background clutter power level for every pixel, thus increasing the computational burden significantly. In order to overcome this limitation, the proposed method uses a fast algorithm to select the Regions of Interest (ROI) based on a global threshold, while the rest pixels are distinguished as clutter directly. The proposed method is verified by experiments with real multi-beam data. The results show that the proposed method can effectively solve the problem of false terrain in a multi-beam terrain survey and achieve a high detection accuracy.

• 한국해양공학회지
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• 제36권1호
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• pp.61-81
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• 2022

The available underwater acoustic spectrum is limited. Therefore, it is imperative to avoid frequency interference from overlapping frequencies of underwater acoustic equipment (UAE) for the co-existence of the UAE. Cognitive technology that senses idle spectrum and actively avoids frequency interference is an efficient method to facilitate the collision-free operation of multiple UAE with overlapping frequencies. Cognitive technology is adopted to identify the frequency usage of UAE to apply cognitive technology. To this end, we investigated two principle underwater acoustic sources: UAE and marine animals. The UAE is classified into five types: underwater acoustic modem, acoustic positioning system, multi-beam echo-sounder, side-scan sonar, and sub-bottom profiler. We analyzed the parameters of the frequency band, directivity, range, and depth, which play a critical role in the design of underwater acoustic cognitive technology. Moreover, the frequency band of several marine species was also examined. The mid-frequency band from 10 - 40 kHz was found to be the busiest. Lastly, this study provides useful insights into the design of underwater acoustic cognitive technologies, where it is essential to avoid interference among the UAE in this mid-frequency band.

• 한국산업융합학회 논문집
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• 제26권1호
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• pp.133-141
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• 2023

Accurate measurement of seafloor topography plays a crucial role in developing marine industries such as maritime safety, resource exploration, environmental protection, and coastal management. The seafloor topography is constructed using side scan sonar (SSS) and single beam echosounder (SBES) or multibeam echosounder (MBES), which transmit and receive ultrasound waves through a device attached to a marine survey vessel. However, the use of a sonar system is affected by noise pollution areas, and the single beam has a limited scope of application. At the same time, the multibeam is mainly applicable for depth observation. For these reasons, it is difficult to determine the boundaries and areas of seafloor topography. Therefore, this study proposes a method to improve the backscatter data of multibeam echosounder, which has a relationship with the seafloor quality, by using digital image processing to classify the shape of the underwater surface.

• 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.

• 수산해양기술연구
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• 제49권3호
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• pp.270-281
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• 2013

Hydro-acoustic surveys with scientific echo sounder were carried out to estimate the total density and distribution of the juvenile cod in Jinhae bay, Korea. The surveys were conducted 4 times from May to June using 2 frequency method (38kHz and 120kHz) and beam trawl were used to investigate the species composition. Also the catch amounts of juvenile cod were compared with the cod density estimated by the hydro-acoustic method. It was confirmed that the juvenile cod was stayed in Jinhae bay in early June and There was the relationship between catch of juvenile cod and the estimated density by hydro-acoustic survey. The number of juvenile cod was consequently about 365,000 fish (CV 12.9%) in May and 113,000 fish (CV 9.2%) in May based on the hydro-acoustic data.

• 수산해양기술연구
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• 제58권2호
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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.