• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.152-153
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• 2005

Side scan sonar System occupies an important position as one of marine survey equipments. The purpose of this research is to express sonar' scan images in underwater and compare with the measured size, shape and the quality of the material. Also we confirm the effectiveness of obtained images using the Side scan sonar.

• 한국기계기술학회지
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• 제13권2호
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• pp.101-106
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• 2011

In this study, the velocity distribution according to upper side coner shape of underwater construction with rectangular cylinder was measured with PIV method and the wake flow characteristics was considered. According to the coner shape, the flow pattern of wake flow was also differed greatly and the step-shaped coner of cut-off ratio B/H=0.06 was similar in the slope shape in result.

• 한국음향학회지
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• 제42권4호
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• pp.370-376
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• 2023

수중영상은 수중 잡음과 낮은 해상도로 표적의 형상과 구분이 명확하지 않다. 그리고 딥러닝의 입력으로 수중영상은 전처리가 필요하며 Segmentation이 선행되어야 한다. 전처리를 하여도 표적은 명확하지 않으며 딥러닝에 의한 탐지, 식별의 성능도 높지 않을 수 있다. 따라서 표적을 구분하며 명확하게 하는 작업이 필요하다. 본 연구에서는 수중영상에서 표적 그림자의 중요성을 확인하고 그림자에 의한 물체 탐지 및 표적 영역 획득, 그리고 수중배경이 없는 표적과 그림자만의 형상이 담긴 데이터를 생성하며 더 나아가 픽셀값이 일정하지 않은 표적과 그림자 영상을 표적은 흰색, 그림자는 흑색, 그리고 배경은 회색의 3-모드의 영상으로 변환하는 과정을 제시한다. 이를 통해 딥러닝의 입력으로 명확히 전처리된 판별이 용이한 영상을 제공할 수 있다. 또한 처리는 Open Source Computer Vision(OpenCV)라이브러리의 영상처리 코드를 사용했으면 처리 속도도 역시 실시간 처리에 적합한 결과를 얻었다.

• 수산해양기술연구
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• 제58권4호
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• pp.289-298
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• 2022

Sea anchor for fishery is commonly used in jigging fishery and purse seine. The study of sea anchor was studied for improvement of opening efficiency and drag by changing the type of shape and the diameter of vent. However, standard specification of sea anchor is not set and has not been studied for underwater stability. Therefore, this study aimed to improve underwater stability of sea anchor by changing a vent diameter and weight of sinker. The experiment was conducted in flume water tank. The experiment model of sea anchor was made from actual model of sea anchor which is used in fishery by similarity law. The model of sea anchor was designed to different types of vent diameter and weight of sinker in different current speed. The value of movement of side to side (X-axis), drag of sea anchor (Y-axis) and movement of up and down (Z-axis) was measured for 30 seconds. Each value of X, Y, Z-axis was analyzed through t-test and ANOVA analysis to verify that each value had a significant difference according to the difference compositions. There was correlation between the movement of X-axis and Z-axis. The drag of sea anchor was stronger as the current speed increased. However, the larger the vent diameter, the weaker the drag. From the result of the standard deviation, the movement of X-axis was inversely proportional to the vent diameter. However, movement of Z-axis was larger as the weight of sinker was the heaviest or lightest from the result of the standard deviation. These results suggest that the sea anchor should be combined with proper size of the vent diameter and the weight of sinker to improve the stability.

• 수산해양기술연구
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• 제41권2호
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• pp.156-164
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• 2005

The size of the ship's turning circle is influenced by various factors, such as block coefficient, underwater side shape, rudder area ratio, draft, trim and Froude's number. Most of them are already fixed on departure from a port. However, the ship's speed and the rudder angle are controllable factors which operations are able to change optionally during sailing. The DGPS measured the turning circles according to the ship's speed and the rudder angle. The maximum advances by slow and full ahead were 302m and 311m, and the maximum transfers were 460m and 452m, respectively. There occurs almost no difference in size of the turning circle by variation of the ship's speeds. When the rudder angles were changed to $10^{\circ}$, $20^{\circ}$ and $30^{\circ}$, the maximum advances were 447m, 271m and 202m, and then also the maximum transfers 657m, 426m and 285m, respectively. The diameter of the tuning circle was decreased exponentially when the rudder angle was increased. The maneuverability was better when the direction of turning and propulsion of propeller are in the opposite direction rather than in the same one togetherm. The distance of the maximum transfer was always bigger than that of the maximum advance.

• 대한조선학회논문집
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• 제42권6호
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• pp.631-636
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• 2005

One and three dimensional whipping response analyses of a naval surface combatant subjected to an underwater explosion bubble pulse were carried out to compare the efficiency and accuracy according to the modeling methods. In 1-D analysis, program UNDEXWHIP developed by KIMM was used, which is based on the thin-walled Timoshenko's beam theory and on the modal analysis method using wetted vibratory modes of the hull girder. In 3-D analysis, three finite element models were suggested using LS-DYNA/USA code, such as 3-D beam model considering geometric shape of wetted side shell, coarse and fine 3-D F.E. models. Through the comparison of results from the 1-D and 3-D analyses, it could be confirmed that 1-D analysis result is in good agreement with 3-D analysis ones, and that fine 3-D F.E. model, shock analysis one, is also used both in the shock response and whipping response analyses for the analyst effort and time savings.

• 전자공학회논문지
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• 제51권4호
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• pp.181-190
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• 2014

수중음향렌즈 시스템은 해저를 탐사하여 고해상도의 영상을 얻어내는 시스템의 하나로 음향렌즈를 이용하여 빔을 형성한다. 음향렌즈를 이용하여 빔을 형성함으로써 복잡도를 낮추고 구동전력을 절감시킨다. 음향렌즈로부터 들어오는 빔을 배열센서로 수신하려면 음향렌즈의 빔패턴을 분석하여 센서간격을 설정하는 문제를 해결해야 한다. 여기서 SIR (Signal to Interference Ratio)을 사용하여 센서간격과 빔패턴과 영상 품질과의 관계를 분석한다. 빔패턴의 모양에 따라 SIR은 변하므로 대체로 센서간격이 넓으면 사이드로브의 영향이 감소하므로 SIR이 개선된다. 사이드로브의 크기가 크면 전반적으로 SIR이 악화된다. Apodization 함수에 따라 빔패턴의 메인로브의 폭과 모양과 사이드로브의 모양과 준위가 바뀐다. 따라서 적절한 apodization 함수를 적용하여 SIR을 개선한다. 본 논문에서 예시된 빔패턴의 경우 센서간격이 13mm에서 SIR이 0-10dB로 안정이 되지만, 그 값이 높지 않다. 따라서 Chebyshev 함수를 적용하여 37mm 이상의 구간에서 80dB의 SIR을 얻는다. 센서간격이 더 작은 경우는 Hann 함수나 triangular 함수가 좋은 성능을 나타냈다.

• 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.

• 한국의류학회지
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• 제48권4호
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• pp.744-755
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• 2024

This study analyzes the characteristics, product dimensions, and ease of haenyeo suits to inform their reproduction. Large, medium, and small haenyeo suits were collected from four manufacturers in Jeju, and their components, cut styles, product dimensions, and ease were analyzed. In the current haenyeo suit design, the upper suit has a collar and a crotch, while the lower suit has a high rise with a gusset. Additionally, there are darts behind the neck in the upper suit and behind the knees in the lower suit. Haenyeo suits have a three-dimensional shape that accommodates the postures needed for haenyeo's underwater activities. The upper suit is finished with a cuffed hem or an uncuffed side seam with a diagonal or stepped cut. The lower suit is cut and sewn with the waist and hem at right angles or with the hem diagonal to the waistline. Haenyeo suit dimensions vary between manufacturers, and the models' body dimensions show that there is little or no ease. In conclusion, haenyeo suit manufacturers currently use the same components; however, they differ in terms of cut styles, sewing methods, dimensions, and designs.

• 수산해양기술연구
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• 제37권4호
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• pp.267-274
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• 2001

어구 크기를 대폭적으로 줄이면서 어획성능을 향상시킨 어구를 개량하고 조업자동화를 이룩할 수 있도록 하기 위하여 신광수산에서 사용하고 있는 실물어구를 가지고 양선간격 및 예망속도의 변화에 따른 해상실험을 통하여 어구 각부의 망고와 수중형상을 측정·분석한 결과를 요약하면 다음과 같다. 1. 실물어구 각 부분의 망고는 양선간격과 예망속도가 증가함에 따라 낮아지는 경향을 보였다. 2. 실물어구의 양선간격에 따른 오비기, 수비, 앞창, 자루 입구, 깔때기와 자루 뒤끝의 망고는 각각 8.4∼6.6, 17.4∼15.7, 17.9∼12.9, 19.0∼l3.6, 8.4∼8.3, 14.7∼11.1m이었고, 각 부분의 전개율은 16∼12, 24∼22, 38∼27, 83∼59, 93∼92, 54∼41%로 나타났다. 3. 실물어구의 예망속도에 따른 오비기, 수비, 앞창, 자루 입구, 깔때기, 자루 뒤끝의 망고는 각각 10.5∼7.7, 21.6∼l9.6, 16.9∼15.2, 17.1∼15.4, 8.2∼8.0, 14.7∼13.7m이었고, 각 부분의 전개율은 각각 19∼14, 30∼27, 36∼32, 74∼67, 91∼89, 54∼51%로 나타났다. 4. 오비기의 망고가 매우 낮게 형성되어 수비와 앞창의 망고가 불안정하고 극히 낮은 전개율로 인하여 포켓현상이 매우 뚜렷하게 나타났다. 5. 실물어구의 예망깊이는 양선간격과 예망속도의 증가에 따라 약간씩 말아지는 현상을 보였는데, 뜸줄 쪽보다는 발줄 쪽이 더 뚜렷하였다.