• 수산해양기술연구
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• 제60권2호
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• pp.186-193
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• 2024

Most fishing nets used in fish cage aquaculture are made of synthetic fibers such as polyamide (PA) and polyethylene (PE). Therefore, it is challenging to maintain the internal volume of the fish cage due to biofouling, which can increase the load on the cage or reduce dissolved oxygen levels by impeding smooth current flow. To address this issue, research has been conducted to replace conventional synthetic fiber cage nets with brass nets, demonstrating certain benefits such as improved productivity and ease of fish cage management. However, given the need for a more thorough examination of brass fishing net weaving technology and performance, this study assessed the optimal weaving method for brass fishing nets to be used in fish cages. Additionally, it provided essential data for the practical application of brass fishing nets by evaluating their weight, tensile strength, elongation, fatigue resistance, and wear resistance. The study concluded that weaving brass fishing nets using the chain link method ensures durability, ease of installation, and compact storage in a scroll-like form. Moreover, due to their superior fatigue and wear resistance properties, brass nets can offer increased utility if appropriate net diameter and length are selected to compensate for their higher weight per unit area and relatively higher cost compared to existing fiber fishing nets.

• 수산해양기술연구
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• 제59권2호
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• pp.125-134
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• 2023

The swimming behavior of pacific bluefin tuna (Thunnus orientalis) in the offshore sea cage of the brass fishing net was observed and analyzed by imaging sonar techniques. The cultured fish spent most of the time swimming a circular path along the circular cage wall and continued to swim only clockwise direction without completely changing the swimming direction during the 23-hour observation time. In addition, changed swimming behaviors were divided into four categories: (a) the behavior of a large group temporarily swimming in the opposite (counter clockwise) direction, (b) the behavior of a small group temporarily swimming in a small circular path, (c) the behavior swimming small circular path in the center of the cage, and (d) the behavior of a large group swimming across the center of the cage. The maximum swimming speed of the cultured fish was from 3.5 to 3.8 TL/s, the mode was from 1.2 to 1.4 TL/s and the swimming speed during the day time was faster than at night time. It was confirmed the cultured fish swam not only on the surface but also near the bottom net of the cage during the day, but swam mainly at the upper part of the cage at night.

• Nuclear Engineering and Technology
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• 제53권1호
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• pp.172-177
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• 2021

The microstructure and texture of three 316L foils of 25 ㎛ thickness, which were subjected to different manufacturing process, were systematically characterized using advance analytical techniques. Then, the electrochemical property of the 316L foils in simulated pressurized water reactor (PWR) solution was analyzed using potentiodynamic polarization. The results showed that final rolling strain and annealing temperature had evident effect on grain size, fraction of recrystallization, grain boundary type and texture distribution. It was suggested that large final rolling strain could transfer Brass texture to Copper texture; low annealing temperature could limit the formation of preferable orientations in the rolling process to reduce anisotropy. Potentiodynamic polarization test showed that all samples exhibited good corrosion performance in the simulated primary PWR solution.

• 한국초지조사료학회지
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• 제17권3호
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• pp.223-230
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• 1997

The experiments were undertaken to investigate the dynamics of $NO_3\;^-$ uptake at low temperature with forage rape(Bmssica napus), barle(Hordeum vulgare) and winter rye (Scale cereale). A net $NO_3\;^-$uptake and the contents of nitrogenous compound in tissues at low temperature ($5^{\circ}C$) were compared with normal temperature ($25^{\circ}C$).The net uptake of $NO_3\;^-$ by Brass ica nqus was the highest among three species at both temperature applied. During 9 hours after temperature treatment, $NO_3\;^-$ uptake of Brassica napus, Hordeum vulgm and Scale c e d e grown at $5^{\circ}C$ decreased to about 31, 50 and 27% compared with those grown at $25^{\circ}C$. $NO_3\;^-$ contents in roots were much sensitively affected by low temperature than those of leaves. Comparing with the plants grown at $25^{\circ}C$, $NO_3\;^-$ contents in roots of increased to 48.3, 38.7 and 53.5% repectively, for Brassica napus, Hordeum vulgare and Scale cereale during 9 days. A relatively less changes in the content of $NH_4\;^+$-N were observed according to the temperature treatment. The ontents of amino acids-N in leaves at $5^{\circ}C$ slightly decreased while that of roods remarkably increased compared with $25^{\circ}C$. Protein-N was the largest pool of nitrogen and its contents in leaves and roots showed a similar response on the temperature treatment. These results suggested that $NO_3\;^-$uptake was inhibited at low temperature. The dynamics of $NO_3\;^-$ uptake could be closely related to the increased concentration of $NO_3\;^-$ and amino acids in roots.

• 폴리머
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• 제29권6호
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• pp.536-542
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• 2005

로크웰 경도시험 조건 중에서 시간과 관련이 있는 인자들이 경도측정 결과에 미치는 영향을 연구하였다. 대상 소재는 PE, PP PVC, PMMA이었으며 압입속도, 시험하중 유지시간, 그리고 계기판독 시점 등을 중심으로 시험한 결과 탄성이 큰 소재일수록 이들 인자들의 영향을 크게 받는 것으로 나타났다. 시험에 소요되는 시간 등을 고려하였을 때 최적 시험 조건은 각기 4, 15, 15초 이었으며 이 기준에 따라 순회 비교시험을 실시하였다. 순회 비교시험 결과 고분자소재의 경도를 제대로 측정하려면 부가하중을 제하하고 나서 계기판독 시점인 15초의 시간을 유지할 수 있는 기능이 중요한 것으로 나타났다. 황동 기준편으로 경도시험기를 간접 검증하는 것만으로는 탄성 회복력이 좋은 고분자 소재의 특성 때문에 경도 측정값의 신뢰도를 보증할 수 없는 것으로 나타났다.