• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.625-637
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• 2022

The southern coast of the East Sea is an important area affected by large warm currents as it connects the coastal waters of Jeju Island, the South Sea, and Dokdo. From 2017 to 2021, the average catch per unit effort (CPUE; kg/day/ship) of set net fishery at six ports in the Gyeongbuk region off the southern coast of the East Sea was the highest in Gampo, Gyeongju, and the lowest in Hupo, Uljin. Although the seasonal variation in the CPUE differed by region and year, it was generally high in autumn. In the set net fishery in Pohang from 2019 to 2021, we identified 72 species, which decreased to 56 species in 2019, 46 in 2020, and 41 in 2021. The species diversity index slightly increased over the three-year periods. We found positive correlations between the total catch (kg) of subtropical species in autumn and the water temperature at 50 m. Among the most abundant species, we found substantially positive correlations between the CPUE of Scomber japonicus, Scomberomous spp. and Carangids. We also noted positive correlations between the CPUE of Todarodes pacificus, Seriola spp. and Carangids.

• Smart Structures and Systems
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• v.29 no.1
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• pp.29-39
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• 2022

Crack detection plays an important role in the maintenance and protection of steel box girder of bridges. However, since the cracks only occupy an extremely small region of the high-resolution images captured from actual conditions, the existing methods cannot deal with this kind of image effectively. To solve this problem, this paper proposed a novel three-stage method based on deep learning technology and morphology operations. The training set and test set used in this paper are composed of 360 images (4928 × 3264 pixels) in steel girder box. The first stage of the proposed model converted high-resolution images into sub-images by using patch-based method and located the region of cracks by CBAM ResNet-50 model. The Recall reaches 0.95 on the test set. The second stage of our method uses the Attention U-Net model to get the accurate geometric edges of cracks based on results in the first stage. The IoU of the segmentation model implemented in this stage attains 0.48. In the third stage of the model, we remove the wrong-predicted isolated points in the predicted results through dilate operation and outlier elimination algorithm. The IoU of test set ascends to 0.70 after this stage. Ablation experiments are conducted to optimize the parameters and further promote the accuracy of the proposed method. The result shows that: (1) the best patch size of sub-images is 1024 × 1024. (2) the CBAM ResNet-50 and the Attention U-Net achieved the best results in the first and the second stage, respectively. (3) Pre-training the model of the first two stages can improve the IoU by 2.9%. In general, our method is of great significance for crack detection.

• Journal of KIISE:Databases
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• v.36 no.6
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• pp.466-475
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• 2009

Considerable research in the field of ontology mapping has been done when information sharing and reuse becomes necessary by a variety of ontology development. Ontology mapping method consists of the lexical, structural, instance, and logical inference similarity computing. Lexical similarity computing used in most ontology mapping methods performs an ontology mapping by using the synonym set defined in the WordNet. In this paper, we define the Super Word Set including the hypenym, hyponym, holonym, and meronym set and propose an ontology mapping method using the Super Word Set. The results of experiments show that our method improves the performance by up to 12%, compared with previous ontology mapping method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.90-101
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• 1998

This paper presents a scheduling method that uses Petri net modeling and heuristic search to handle the tool setup. In manufacturing systems, a tool is attached to a particular machine to process a particular operation. The activity to attach a tool to a particular machine and detach the tool from the machine requires time. The processing time of operations varies according to the attached tool and the machine used. The method proposed in this paper uses Petri net to model these characteristics and applies a search algorithm to the reachability graph of the Petri net model to generate an optimal or near-optimal schedule. New heuristic functions are developed for efficient search. The experimental results that show the effectiveness of the proposed method are presented.

• Korean Journal of Mathematics
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• v.10 no.1
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• pp.5-10
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• 2002

In this paper, we investigate the prefilter base on a fuzzy set and fuzzy net ${\varphi}$ on the fuzzy topological space (X,${\delta}$). And we show that the prefilter base $\mathcal{B}({\varphi})$ determines by the fuzzy net ${\varphi}$ converge to a fuzzy point $p$ iff the fuzzy net ${\varphi}$ converge to a fuzzy point $p$. Also we prove that if the prefilter base $\mathcal{B}$ converge to a fuzzy point $p$, then the $\mathcal{B}$ has the cluster point $p$.

• The Journal of Fisheries Business Administration
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• v.24 no.2
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• pp.69-82
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• 1993

The purpose of this paper is to estimate production function in the coastal fishing, especially long bag set net fishing and trap fishing using Cobb-Douglas production function with the three main variables: fishing quantity per tonage(WQFP), the number of working persons per tonage(WEMP), and the number of utilized fishing equipments per tonage(WEQU). The statistical results of such estimation reveal that fishing quantity per tonage can be expressed as a function of the number of working persons per tonage and the number of utilized fishing equipments per tonage. The estimated coefficients of WEMP and WEQU are statistically significant and also satisfy the requirements of Cobb-Douglas production function. This study also estimates marginal rate of technical substitution of labor in terms of capital (MRT $S_{LK}$ )in each long bag set net fishing and trap fishing. The resuits of this study show us that trap fishing has the technical characteristic of constant returns to scale(CRS) but long bag net fishing has that of decreassing returns to scale(DRS).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.2
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• pp.54-60
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• 1989

This paper described on the tracking of an individual fish at the fishing ground of set net by use of a small ultrasonic fish tag. The apparatuses used were composed with a tag, three receivers and two time-interval counter oscilloscope. A pulsed ultrasonic transmitter tag fitted to back of a dorsal fin of a yellowtail specimen, Seriola quinqueradidta TEMMINCK et SCHLEGEL is tracked by measuring differences in the time of arrival of the acoustic pulses at an arrangement of three receivers in the freeding tank. The successive positions of the fish were calculated from the differences in the received time of the signals. A fish carying the tag was tracked in the fishing ground of set net by use of the hydrophone and Loran-C. The results of the tests showed that this method gave good positional information to track the movement of an individual fish in the fishing ground of set net.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.24 no.2
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• pp.71-77
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• 1988

The authors analyzed the daily catch data which were obtained from two different regions at the Southern Sea in Korea, Neungpo, Geoje island and Yangwhagum, Namhae island, during three or four years in 1978, 1981-1985, in order to know the fishing characteristics of the set net fisheries. The favorable fishing season was summer in the southern sea. The total catches during one year were greatly affected by those several day when the dominant species of fish were caught in large quantities. The dominant species of fish at Neungpo were little horse mackerel, sand lance, sardine, hair tail, spanish mackerel and common mackerel, and those at Yangwhagun were anchovy, little horse mackerel, sardine, spanish mackerel and gizzard shad, in order of catch. Especially, the little horse mackerel and the sardine appeared to make up very big schools at both Neungpo and Yangwhagum. The occurrence seasons of the dominant species were different by the region, but generally those were earlier at western part than at eastern part of the Southern Sea in Korea.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.3
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• pp.36-41
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• 1986

Uederwater ambient noise was measured at the set net in the Neung-Po Eay. The environment characteristics depend upon oceanographic conditions of sound propagation and its implication on the source of ambient noise. The results of measurement and analysis were as follows: 1. The frequency of the maximum noise level of two passenger. vessels was around 300 Hz. The spectrum level of the fast vessel (the Air-Ferry) was lower than the little slow vessel (the Olympic) between 50-150 Hz in frequences. 2. The spectrum level of the surface in the playground of the set net was lower than the deeper water till 500 Hz, but over that frequency the level was getting lower as the depth was deep. 3. The spectrum level outside the bag of the set net was greater than the inside between 50 and 700 Hz, but over 1,500 Hz the level inside the bag was higher than the outside. 4. The spectrum level of the outside of the breeding tank was higher than the inside in the daytime. However at night opposite phenomenon occurs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.120-128
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• 2003

Fishes were caught by a set net in the coastal waters off Yosu, Korea from April to October, 2001, and seasonal variation of abundance and species composition were studied. Fifty two species were identified as fish $(89\%)\;cephalopods\;(10\%)\;and\;crustaeans\;(1\%).$ Of the fishes Engraulis japonicus, Trachurus japonicus and Trichiurus lepturus were dominant species representing $64.1\%$ in total number of individuals. The number of species was high in spring and low in summer; number of individuals was high in spring and low in autumn. The diversity index (H') was 0.4-0.7 The abundance and species composition fluctuated seasonally. Occurrence of the various stages of fishes indicated that Scombia japonicus, T. japonicus and E japonicus utilized in the area as spawning ground, Conger myriaster larvae, Ammodytes personatus and Seriola quinqueradiata as nursery ground, and T. lepturus and Ilisha elongata as spawning and nursery grounds.