• 수산해양기술연구
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• 제22권2호
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• pp.40-45
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• 1986

In this paper, the I-resistance curve of low-carbon steel with 3 mm thickness was investigated for various crack ratios. The experiments were carried out for the center cracked tension (CCT) specimen with about 50 mm width on an instron machine. The plane stress fracture toughness obtained by the Simpson's formula was Ii. = 24.96 kgffmm. Simpson's formula which considers crack growth in obtaining J integral showed more conservative lin than Rice's and Sumpter's. For materials that may be approximated by the Ramberg and Osgood stress strain law, the relevant crack parameters like the J integral, load line displacement are approximately normalized. Crack driving forces in terms of the I integral are computed for low-carbon steel CCT specimen using the above estimation scheme. Comparison of the prediction with actual experimental measurements by Simpson's formula showed good agreement for several different sized specimen.

• 한국수산과학회지
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• 제53권2호
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• pp.209-217
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• 2020

The purpose of this study was to compare the model-predicted and experimentally measured target strength (TS) of golden cuttlefish Sepia esculenta cuttlebones. Ultrasonic signals used to estimate frequency-dependent TS and the speed of sound in cuttlebones were measured by pulse-echo and through-transmission techniques, using a chirp sonar system and an ultrasonic pulser/receiver system under controlled laboratory conditions. The model appeared to slightly underestimate the predicted TS values in the frequency range of 100-160 kHz. However, there was good agreement between the predicted and measured TS values in the frequency range of 160-200 kHz. The significant similarity between the model-predicted and experimentally measured TS values supports the use of the Kirchhoff-ray mode (KRM) model for acoustic scattering analysis of cuttlebones. Accordingly, we concluded that the KRM model can be used as a tool to evaluate the frequency-dependent variability of TS due to changes in golden cuttlefish swimming depth.

• 수산해양교육연구
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• 제26권5호
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• pp.1090-1095
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• 2014

The experimental and numerical studies of the single-phase flow pressure drop in parallel micro-channels were performed. The parallel micro-channels consisted of 15 channels with depth 0.2mm, width 0.45mm and length 60mm. The FC-72 was used as the working fluid and the mass fluxes ranged from 62.8 to $1371.6kg/m^2s$. The numerical analysis was performed iterative calculations to solve governing equations and finds the appropriate value. The experimental data was compared with the numerical data, the results showed good agreement with the numerical data.

• Fisheries and Aquatic Sciences
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• 제15권1호
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• pp.73-76
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• 2012

Dichloromethane, ethanol, and boiling water extracts of the brown alga Ecklonia cava were examined in vivo for their antipyretic, analgesic, and anti-inflammatory activities in mice. These activities were evaluated by yeast-induced pyrexia, tail-flick test, and phorbol myristate acetate-induced inflammation (edema, erythema, and blood flow). Ethanol extract of E. cava (0.4 mg/ear) inhibited the inflammatory symptoms of mouse ear edema, erythema, and blood flow by 82.6%, 69.0%, and 65.4%, respectively. This extract also demonstrated potent analgesic activity. No acute toxicity was observed after p.o. administration of each extract (5 g/kg bw). These in vivo data are in agreement with the claims of the health care industry and indigenous medicine that E. cava is an effective remedy for inflammation-related symptoms.

• 한국수산과학회지
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• 제44권2호
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• pp.167-172
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• 2011

A three-dimensional ecological model (EMT-3D) was applied to Tokyo Bay to simulate 4,4'-bis (2-sulfostyryl)biphenyl (DSBP). The simulated results were in good agreement with the observed values, with a correlation coefficient of R=0.8431 and a coefficient of determination of $R^2$=0.7108. The sensitivity analysis indicated that the photolysis rate is the most important factor. Therefore, the parameters must be considered carefully in modeling. The mass balance results showed that the standing stock of DSBP in water and in particulate organic carbon was 621.2 and 19.5 kg, respectively, and the effluent flux to the open sea was 2.63 and 0.055 kg/day, respectively.

• 수산해양기술연구
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• 제55권2호
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• pp.172-180
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• 2019

In this study, a ship motion control system design method is introduced for autonomous ships. Some related research results and technologies for autonomous ships have already been developed and applied to testing ships. Recently, the Norwegian Maritime Authority and the Coastal Administration have signed an agreement and started to test autonomous ships in the defined area. Considering recent technology trends and background, in this paper, the authors also try to develop autonomous ship control technologies. In the designed control system, an observer is introduced to estimate unmeasurable system states. Based on the servosystem with state estimator, ship motion control experiment is performed to evaluate control performance using a model ship in water basin.

• 현장농수산연구지
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• 제4권1호
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• pp.3-28
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• 2002

This study was carried to devise comprehensive policies for systematically fostering the eligible farmers in Korea based on their vocational developing stages such as potential stage in juvenile days, preparing stage in agricultural schools and colleges, farm worker stage under farm manager, ownership farming stage and professional farm manager stage. Of course all of these developing stages are not necessary but desirable processing to be a good farmer. At least more than two stages are necessary to be a professional farm manager. In order to systematically foster the eligible farmers as many as demanded in Korea, appropriate policies in the every stage should be devised. As the result of this study, several programs were sugested as the appropriate policies such as development of school 4-H program in potential stage, scholarship program in preparing stage, supporting programs for the farmhouse-hold having a family's farm management agreement, development of the instalment savings program for the young farm workers and farmer's certificate program, etc.

• 수산해양기술연구
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• 제50권4호
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• pp.427-434
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• 2014

Although ex situ target strength (TS) measurements using dual- and split-beam systems have become the primary approach of estimating fish abundance, theoretical model estimation is a powerful tool for verifying the measurements, as well as for providing values when making direct measurements is difficult. TS values for 20 samples of live bambooleaf wrasse (Pseudolabrus japonicus) whose target length (TL) ranged between 13.7 and 21.3 cm were estimated theoretically using the Kirchhoff-ray mode model, and the TS values for 18 live fish samples were additionally measured at ${\sim}0^{\circ}$ tilt angle to the swimming aspect using a tethered method at a frequency of 120 kHz to verify the theoretical values. The digitizing intervals used to extract the fish body and swim bladder morphology in the X-ray photographs significantly affected the calculated TS patterns, but variations based on the speed of sound and density ratio values for the general range of fish flesh were relatively small (within 1 dB). Close agreement was observed between the measured and theoretical TS values, and the correlation between the average TS and body length of the fish could be calculated accurately as <$TS_{120kHz}$>= 20logTL (cm) -71.6 using the theoretical method.

• 수산경영론집
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• 제50권2호
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• pp.57-74
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• 2019

This study is aimed to evaluate the technology levels of shellfish farming in southern coast of Korea and status analysis on research of shellfish aquaculture. With achieving these objectives, it will be possible to present the direction of shellfish farming research and related project. Five major breed of shellfish aquaculture that would be adaptive and sustainable were proposed through consultation and agreement with professional group with more than 15 years of working experience. Moreover also evaluated that levels of technology, industry and market are also evaluated. The evaluation result of the expert group showed that the shellfish farming level occupied the third place in comparison with the US, Japan, Europe, and China. It is estimated that about 13~14 years will reach the level of the highest on average. In addition, most countries are expected to grow by about 10% on average over the next five years. Based on the result of the analysis of 670 research projects (2008~2017), there was little research on climate change and shellfish aquaculture. Besides some of shellfish have not been studied since 2008 and 2013, so it can be mentioned as a future task to be overcome.

• 수산해양교육연구
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• 제26권5호
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• pp.1165-1174
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• 2014

The research was conducted on 238 marine sports participants by clarifying the relationship among self-efficacy, sociality, and organization culture, to eliminate the organizational(home, school, club, workplace, etc.) culture maladjustment phenomenon which is caused by personal stress, the lack of physical activity, and the lack of sociality due to the rapid change of modern society and enhance sociality, adjustment to society and the lack of creativity due to the rigid hierarchy and contribute to organization culture through marine sports among sports which we enjoy with nature. Firstly, according to general self-efficacy, and social characteristics of the organizational culture and the gender differences in higher than women in all sub-variables of the sub-factors of self-efficacy and self-regulation, sociability, organizational culture, sub-culture and develop cultural factors agreed man showed that in the sub-factors of organization culture showed that the development of high culture and hierarchical culture in the age of 20s. Secondly, in terms of the effect of self-efficacy of marine sports participants on sociality, it is found that self-regulation and level of difficulty positively influence on the culture of agreement, the culture of development and the culture of hierarchy. Lastly, in terms of the effect of self-efficacy of marine sports participants on organizational culture, it is shown that self-regulation has positive influence on the culture of agreement, the culture of development and the culture of hierarchy.