• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.2
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• pp.134-148
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• 2021

During the ichthyoplankton survey around the Chilsan Island (previously known as the biggest spawning ground of the Sciaenidae) in the southwestern sea of Korea from April to June in 2019 using ring nets, we collected a total of 12 individuals belonging to the family Sciaenidae. Using molecular methods, we identified five sciaenid species (Collichthys lucidus, Collichthys niveatus, Johnius grypotus, Nibea albiflora, and Pennahia argentata), and described and compared them on the basis of the preflexion larval stage. C. lucidus was well distinguished by the presence of occipital crests at preflexion stage. Although there were no occipital crests, preflexion larva of C. niveatus was distinguished by the absence of melanophore except for the upper part of the abdominal cavity. J. grypotus and N. albiflora were very similar morphologically, but were distinguished by myomere height (15.22-15.53% in J. grypotus vs. 11.66-12.78% in N. albiflora) in the percentage of notochord length, and eye diameter (32.58-33.37% in J. grypotus vs. 40.32-42.53% in N. albiflora) in the percentage of head length between specimens of similar size (J. grypotus: 3.22-3.23 mm, N. albiflora: 3.04-3.13 mm). P. argentata were distinguished by distribution of ventral caudal melanophore (one row of small spot in P. argentata vs. irregular patches on the central part of caudal in J. grypotus and N. albiflora). Comparative morphological studies using more diverse species must be conducted for more comprehensive understanding of the morphogenesis of Sciaenidae.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.2
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• pp.117-126
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• 2021

Diet composition and trophic level of Trachurus japonicus were studied using 417 specimens collected by trawls, set nets and purse seine fisheries from March 2019 to February 2020 in the South Sea of Korea. The size of T. Japonicus ranged from 7.0 to 49.8 cm in total length. T. japonicus were a carnivore that fed mainly on euphausiids and pisces. In eddition, T. japonicus fed on small quantities of cephalopods, crabs etc. T. japonicus showed ontogenetic changes in feeding habits. The proportion of euphausiids decreased inversely proportional to body size whereas the consumption of pisces gradually increased. As body size of T. japonicus increased the mean number of prey per stomach and the mean weight of prey per stomach tended to increase, but the mean number of prey per stomach was not significantly different. As a result of the feeding strategy analysis, T. japonicus were specialized feeders with pisces and euphausiids as their dominant prey. The trophic level ranged between 3.57 ± 0.54 and 3.91 ± 0.65, and increased asymptotically with size of specimens. The average trophic level of the T. japonicus was 3.79 ± 0.61.

• Journal of Digital Convergence
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• v.19 no.3
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• pp.295-302
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• 2021

The purpose of this paper is to pay attention to the problems of the elderly in our society, which is facing an aged society, to understand the lives of the elderly and to recognize the need for retirement and death preparation. It reviews and analyzes the story of So-young, the main character of the movie "Killing Woman," according to the context of the work. The narrative of the film illustrates the problems of suffering for the elderly, such as poverty, disease, dementia, loneliness, and fear of death. In the face of the ultra-aged era, institutional supplementation measures for underprivileged senior citizens at the national level should be established, and social interest and safety nets should be secured, and specific retirement preparations are needed personally. Furthermore, support for research and education of old age preparation education programs and death education programs to prepare for retirement and death should be continuously provided.

• Journal of the Korean GEO-environmental Society
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• v.23 no.2
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• pp.37-47
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• 2022

Recently, with the establishment of active stabilization measures, large-scale collapse of slopes is decreasing. However, the frequency of rockfalls due to the destabilization of floating stones or boulder within or above the slope has not been decreased significantly. As a measure for stabilizing rockfall and disaster prevention, protection methods such as rockfall barriers and rockfall protection nets are typically applied. However, the approach to catching the rockfall in a catchment area by reducing the energy of the rockfall and changing the rolling condition of the rockfall is relatively insignificant. Therefore, in this study, using a general-purpose rockfall simulation program, the change in the rolling characteristics of rockfall according to the specifications of the ditch installed under the slope was investigated. It is expected that the research results can be used as basic data to determine the specifications of the ditch that can be applied to general roads or trails.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.6
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• pp.435-444
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• 2022

This study conducts capture simulations of space debris using a space-net. The present capture simulations are performed using ABAQUS, a nonlinear structural dynamics analysis code. A square space-net with 1 m × 1 m and a space debris with a cube configuration(0.3 m × 0.3 m × 0.3 m and 30 kg) are considered as baseline models. Using the baseline models, the capture simulation using ABAQUS is conducted to understand the capture process and establish the criteria of capture success or fail. In addition, the capture simulations are performed when various properties of the space-net are considered, and it is investigated that major design factors of the space-net are recognized to capture successfully the space debris.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.1
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• pp.19-31
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• 2022

Damages by jellyfish are occurring frequently around the world. Among them, accidents caused by jellyfish stings are serious enough to cause death. So we designed a jellyfish blocking net and analyzed its stability to prevent sting caused by jellyfish entering the beach. To this end, the dynamic behavior of the jellyfish blocking net according to the current speed (0.25-1.0 m/s) and the net type (50, 100 and 150 mm) on the upper part of the blocking net was modeled using the mass spring model. As a result of simulations for the model, the horizontal tension (horizontal component of the mooring tension) of the mooring line increased with the decrease in the mesh size on the upper part of the blocking net at all current speeds, but exceeded the holding force at high tides faster than 0.5 m/s and exceeded the holding force at all current speeds at low tide. Therefore, the jellyfish blocking nets showed poor stability overall. The depth of the float line had a little difference according to the upper mesh size and increased lineary proportional to the current speed. However, the float line sank too much to block the incoming jellyfish. These analysis results helped us find ways to improve the stability of the jellyfish blocking net, such as adjusting the length of the mooring line and improving the holding power. Therefore, it is expected that this technology will be applied us various underwater structures to discover the weaknesses of the structures and contribute to increasing the stability in the future.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.4
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• pp.271-282
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• 2021

This study aims to understand the opening efficiency of the finless porpoise escape guide net by the type of extension net that is the part to which the escape guide net is attached in stow net. To this end, extension nets were manufactured in full size and the net mouth area and towing tension were investigated according to the towing speed (0.2, 0.4, 0.6 and 0.8 m/s) and the type of extension net (25 mm net and raschel net) in the water tank. As a result, the net mouth area of the guide net was larger when the raschel net was used for the extension net than when the 25 mm net was used under all towing speeds. In addition, regardless of the type of extension net, the net mouth area reached about 80% of the maximum value at a towing speed of 0.4 m/s. In the field, fishing operation of stow net is performed only when the current speed is above 0.4 m/s. Therefore, the speed of 0.4 m/s was confirmed as a meaningful value to determine whether it is possible to operate. As a result of analyzing the relationship between the net mouth area of the guide net and the towing tension, it was confirmed that the difference in the net mouth area of the guide net according to the type of the extension net was due to the difference in the solidity ratio.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.199-206
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• 2021

This paper describes the feasibility and reliability verification of installing a protective structure to protect attack periscopes. The attack periscope is the critical equipment of a submarine to enable the user to monitor surface and air activity, collect navigational data, and detect and identify targets. The attack periscope provides target information acquired through TV, IR camera, and laser range finder to the combat system. In the product improvement program, the upper part of the masts was exposed to the outside of the sail because the existing attack periscope was replaced with a new one. On the other hand, the head sensor can be damaged by floating objects, such as fishing nets, during sea navigation. Therefore, the installation of a protective structure for an attack periscope improved the equipment operation performance. The feasibility and reliability of the installation of the protective structure were verified by examining the influence of URN.

• Korean Journal of Community Nutrition
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• v.26 no.6
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• pp.429-440
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• 2021

Objectives: Standardized guidelines and reference points for a food security policy are necessary to guarantee that basic social safety nets work properly. Therefore, this study aimed to explore the basic concepts and detailed dimensions of food security, including the potential relevant indicators, and sought to establish standardized well-being baselines. Methods: A literature review and 14 expert roundtable discussions were carried out to analyze and extract the key concepts of food security. After determining these concepts and detailed dimensions of food security, a conceptual framework was modeled. Then, indicators for each local government that could be monitored and evaluated for each sub-area were suggested. Results: The concept of food security was defined as follows: Individuals should be provided with sufficient, safe, and quality food, which should be accessible to the community and available for use to achieve health and well-being. In addition, food security should be ensured sustainably in a changing environment. Four dimensions were suggested while conceptualizing food security. First, sufficient food, which means sufficient food supply in quantity, quality, and safety. Second, equitable food which includes creating environments in which high-quality and safe food can be purchased at an appropriate price and can be provided regardless of the socioeconomic gap. Third, healthy food which should be provided to promote people's health and happiness through the eco-friendly consumption of food. Fourth, sustainable food, which can be supplied in a sustainable manner and as part of an eco-friendly food system that considers the conservation of natural environments. Conclusions: The basic concepts and detailed areas of food security including the potential indicators proposed in this study, may be useful for developing and implementing various policies and programs to support food and nutrition security in the future.

• Journal of Broadcast Engineering
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• v.27 no.6
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• pp.840-847
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• 2022

In a deep neural network (DNN)-based speech enhancement, using global and local input speech information is closely related to model performance. Recently, a nested U-Net structure that utilizes global and local input data information using multi-scale has bee n proposed. This nested U-Net was also applied to speech enhancement and showed outstanding performance. However, a single skip connection used in nested U-Nets must be modified for the nested structure. In this paper, we propose a multi-level skip connection (MLS) to optimize the performance of the nested U-Net-based speech enhancement algorithm. As a result, the proposed MLS showed excellent performance improvement in various objective evaluation metrics compared to the standard skip connection, which means th at the MLS can optimize the performance of the nested U-Net-based speech enhancement algorithm. In addition, the final proposed m odel showed superior performance compared to other DNN-based speech enhancement models.