• Korean Journal of Ichthyology
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• v.28 no.4
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• pp.223-228
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• 2016

The anatomy and histology of the olfactory organ in Oryzias sinensis was researched using a stereo microscope and light microscope. In the gross structure, the paired olfactory organs on the dorsal part of the head consist of two nostrils (a circular anterior nostril and a slit posterior nostril in a distance), a single olfactory chamber and a single accessory nasal sac. In the histological study, the epithelium of the olfactory chamber is classified into both sensory and non-sensory regions. The sensory epithelium consists of olfactory receptor neurons, supporting cells, basal cells and vesicles, and is islet in distributional pattern. The non-sensory epithelium is composed of stratified epithelial cells and two types of mucous cells (acidic and neutral cells). The epithelium of the accessory nasal sac has swollen stratified epithelial cells, mucous cells with a rich glycoprotein. Such an olfactory anatomy and histology of O. sinensis may reflect its habitat surrounding stagnant and polluted water.

• Korean Journal of Ichthyology
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• v.31 no.2
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• pp.77-82
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• 2019

The feeding habits of pacific cod (Gadus macrocephalus) were studied by analyses of stomach contents. Specimens of G. macrocephalus (n=407) were collected from the western coastal waters of Korea, monthly from July 2017 to June 2018. The size of G. macrocephalus ranged from 30.4 to 86.0 cm in total length (TL). G. macrocephalus was consumed mainly Pisces (71.5%) and Caridea (24.2%) based on % IRI, whereas other prey items including, Paguroidea, Euphausiacea and Cephalopods showed a low contribution to the diet. The feeding ratio of Caridea decreased with increasing fish size. While this decrease paralleled the increased consumption of fish preys. The feeding ratios of Pisces were the highest during spring, autumn and winter, whereas the proportion of Caridea was higher in summer.

• Korean Journal of Ichthyology
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• v.31 no.1
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• pp.54-61
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• 2019

A study on the diel activities and feeding habits of Pseudobagrus brevicorpus living in the Daegacheon Stream of Nakdonggang River was conducted in September 2017. Diel activity took place during the night, just after sunset and just before sunrise. Pseudobagrus brevicorpus swam in the middle depths, and when they found prey organisms, approached and consumed them immediately. Fish were divided by age into three groups. Prey organisms whose index of relative importance in the stomach contents exceeded 1% belonged to the orders Ephemeroptera (80.8%), Diptera (8.6%), and Trichoptera (8.5%). An index of relative importance by age showed that the Ephemeroptera are very important prey organisms, and the sizes of prey organisms increase with fish growth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.728-733
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• 2023

The diet composition of octopus Octopus vulgaris was studied using 392 specimens collected from January to December 2020 in the coastal waters of Yeosu, Korea. The body weight ranged from 86.4 to 3,645.4 g. The most important prey item in the diet of O. vulgaris was decapods, which constituted 43.9% in ranking index (%RI). The second largest prey item was Pisces (%RI=27.9%), and cephalopods (%RI=21.8%) constituted the third largest prey item. The average trophic level of O. vulgaris was 3.97±0.59. Ontogenetic changes were significant among size classes (<400 g, 400-800 g, ≥800 g). The small size class (<400 g) mainly fed on decapods, whereas the medium (400-800 g) and large size (≥800 g) classes mainly fed on cephalopods and Pisces, respectively. The dietary composition varied significantly with season.

• Animal cells and systems
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• v.5 no.4
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• pp.313-317
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• 2001

The sequential assessment model describes a fight between two conspecific as an ongoing statistical sampling process, which makes it possible to predict fight length or repetition number of a behavioral element depending on relative RHP (resource holding potential: e.g. weight or fighting ability). We staged contests between males of common freshwater gobies to test some predictions of this model. Fights proceeded in a consistent sequence of phases. Most contests began with two contestants adopting lateral display, and then escalated to intense physical contacts. The length of contests was negatively correlated with weight difference between the contestants. The duration of complete phases was, however, independent of weight, and the prior information gained during complete phases did not appear to affect subsequent phases of the fight. Our results show that the contests of common freshwater gobies are well predicted by the sequential assessment model.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1938-1940
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• 1999

Trench-Gate structures are proposed to improve the breakdown voltage of LDMOS as well as the second breakdown under forward biased gate. Two dimensional device simulator PISCES II has been used to explain the effects of the drift layer thickness on the breakdown voltage of the conventional LDMOS and Trench Gate LDMOS in terms of potential contour lines. The Trench Gate structure has shown improvements in the breakdown voltage by about 44% and 84% for $V_G$=0 V and $V_G$=15 V respectively.

• Journal of Ecology and Environment
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• v.31 no.2
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• pp.107-113
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• 2008

We measured a set of 37 morphological characteristics in 97 specimens of adult Korean chub, Zacco koreanus, trapped in the Milyang River, Korea, in May and October of 2005. Twelve out of thirty-seven morphometric measurements were significantly different between the sexes. In particular, both the pectoral fin length and the direct distance between the insertion of the dorsal fin and the insertion of the anal fin were highly significant (p < 0.001). This sexual dimorphism may reflect the outcome of sexual selection in this species.

• Korean Journal of Ichthyology
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• v.2 no.1
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• pp.47-52
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• 1990

Anew species of cyprinid fish Acheilognathus koreensis is described from specimens collected in several rivers of southern part of Korea. In general aspect it is similar to A. liηzbata but differs form this by having large snout length, narrow interorbital width and characters of early developmental stage. The new species is distinguished from A. signifer by color parttern of dorsal and anal fin ray in male, and egg form and ovipositor length in female.

• Korean Journal of Ichthyology
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• v.3 no.1
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• pp.42-47
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• 1991

A suspected intergeneric hybrid cross between Pungtungia herzi and Pseudopungtungia nigra was collected at the Ungcheon River. Overall hybrid index did not show the hybrid connection clearly, but the most striking key character between two genus, pigmentation on the all fins except pectoral, the shape and position of the mouth part appeared to show the intermediary. So this specimen was thought to be an intergeneric natural hybrid which merits further study.

• Animal Systematics, Evolution and Diversity
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• v.29 no.1
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• pp.18-22
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• 2013

A recent study on the mitochondrial genetic variation of the Carassius auratus population in South Korea suggested that there are 3 distinct mitochondrial lineages in the country, and that they are geographically separated between westward rivers and southward rivers, respectively. In this study, the population genetic structure of amplified fragment length polymorphism (AFLP) of Carassius auratus was investigated. The results of analysis of molecular variance (AMOVA) supported the geographic distinction between westward and southward river populations, but only 3.66% of total genetic variance lies among these populations. The panmicticity of the AFLP genetic variation is backed up by the results of the neighbor-joining dendrogram drawn from a linearized pairwise $F_{ST}$ matrix and Bayesian clustering analysis. The discordance of genetic structure between mitochondrial and AFLP genetic variation may come from difference in effective population size between these markers and/or gene flow between westward and southward river populations through river capture events.