• Journal of Intelligence and Information Systems
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• v.17 no.3
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• pp.99-114
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• 2011

Collaborative Filtering (CF) suffers from two major problems:sparsity and cold-start recommendation. This paper focuses on the cold-start problem for new customers with no purchase records and the sparsity problem for the customers with very few purchase records. For the purpose, we propose a method for the new customer recommendation by using a combined measure based on three well-used centrality measures to identify the customers who are most likely to become neighbors of the new customer. To alleviate the sparsity problem, we also propose a hybrid approach that applies our method to customers with very few purchase records and CF to the other customers with sufficient purchases. To evaluate the effectiveness of our method, we have conducted several experiments using a data set from a department store in Korea. The experiment results show that the combination of two measures makes better recommendations than not only a single measure but also the best-seller-based method and that the performance is improved when applying the hybrid approach.

• Journal of Species Research
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• v.10 no.4
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• pp.387-391
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• 2021

Araneidae Clerck, 1757 is one of the largest families within the order Araneae Clerck, 1757, comprising 3,065 species in 177 genera. To date, two species of the genus Mengora O. Pickard-Cambridge, 1889 and four species of the genus Araniella Chamberlin & Ivie, 1942 have been recorded in Korea. During a seasonal survey of the spider fauna in mountainous terrain conducted from 2018 to 2019, females of Mangora foliosa Zhu & Yin, 1998 and a male of Araniella robusta sp. nov. were collected with a sweep net between shrubs in mixed forests from Mt. Juwangsan National Park. In this paper, we provide a diagnosis of the new species and descriptions including measurements and morphological illustrations. The new species, Araniella robusta sp. nov., can be easily distinguished from other species in the genus Araniella Chamberlin & Ivie, 1942 by a branched conductor with two blunt tips and conjugation of the embolus tip and terminal apophysis.

• Journal of Species Research
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• v.2 no.2
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• pp.145-158
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• 2013

Candoninae is the most diverse group of freshwater ostracods with over 300 living species described from all around the world. However, only 11 species have been reported from South Korea. Considering abundant freshwater ecosystems here this number is very low. It is no wonder that newly collected samples of freshwater meiofauna often contain Candoninae ostracods which are new records for South Korea, or new taxa. Earicandona mounchyon gen. nov. sp. nov. and Typhlocypris (Pseudocandona) pratensis (Hartwig, 1901) were collected from two open freshwater bodies in Gangwon-do, and Gyeongsangbuk-do in South Korea. The new genus is most closely related to the breuili-group of Fabaeformiscandona Krstic, 1972. The most important apomorphic character of the new genus is a hemipenis with a poorly sclerified lobe "g", and prehensile palps with more rounded dorsal margins. Beside the new species, Earicandona contains only E. okuboi (Smith & Janz, 2008) comb. nov. from Lake Biwa. This species was originally described in Fabaeformiscandona, fabaeformis-group. They differ mostly in the morphology of the shell, but also some details of soft body, including the more pronounced genital process in the Korean species. Typhlocypris pratensis was so far known from Europe and this finding significantly broadens its area of distribution. Both Typhlocypris and Earicandona belong to the tribe Candonini and the key to the genera of this tribe is also presented here.

• Mycobiology
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• v.44 no.3
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• pp.137-145
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• 2016

Most known species in the Strophariaceae are decomposers and grow on various kind of organic matter. Approximately 18 genera and 1,316 species in the Strophariaceae have been reported worldwide. Through an ongoing survey of indigenous fungi in Korea, 29 specimens belonging to the Strophariaceae were collected from 2012 to 2016. These specimens were identified based on morphological characteristics and molecular analysis of internal transcribed spacer sequences. Fifteen taxa were confirmed, with eight species matching those previously recorded. Seven species in five genera were shown to be new records in Korea: Galerina marginata, Gymnopilus crociphyllus, Gymnopilus picreus, Hebeloma birrus, Hebeloma cavipes, Pholiota multicingulata, and Psilocybe thaizapoteca. In this study, we provide detailed morphological descriptions of these species and investigate their evolutionary relationships by constructing phylogenetic trees.

• Journal of Species Research
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• v.6 no.spc
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• pp.1-7
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• 2017

Eight samples, collected from six moss-covered soil and two freshwater samples, were examined to determine ciliate diversity in Korea. Based on the morphology of living and stained specimens, thirteen ciliate species, previously unrecorded in Korea, were identified. These specimens were classified to four classes, seven orders, ten families, and twelve genera. Of these genera, the following six were first records in Korea: Bresslauides, Dexiotricha, Glaucoma, Paragastrostyla, Sathrophilus, and Trithigmostoma. Here, we provide a brief description of the morphology of these 13 taxa along with microphotographs and notes.

• Animal Systematics, Evolution and Diversity
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• v.32 no.3
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• pp.234-239
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• 2016

Two species of mantid shrimps were collected from southern part of Korea and identified as Kempella mikado and Squilloides leptosquilla of the Squillidae. The former species is characterized by having a dactylus of the raptorial claw with six teeth, only the fifth thoracic somite with a single spinous lateral process, and the fifth abdominal somite with a pair of black dorsal patches. However, the latter species is characterized by having a dactylus of the raptorial claw with four teeth, and the fifth to seventh thoracic somites each with a single lateral process. Both species are described with figures and photographs. The present records are extensions of their geographical distributions and new records in Korea. Hence, a total of six species of the stomatopods have been recorded in Korea up to date: Oratosquilla oratoria, Faughnia formosae, Taku spinosocarinatus, Chorisquilla spinosissima, Kempella mikado, and Squilloides leptosquilla.

• Animal Systematics, Evolution and Diversity
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• v.24 no.1
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• pp.17-24
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• 2008

Three crab species, Macromedaeus orientalis, Eriphia smithi, and Ocypode cordimana, from Jejudo Island are recorded for the first time in Korea. M. orientalis was collected under the rocks by SCUBA diving in 20m and at low tidal mark. However, E. smithi and O. cordimana were collected in crevices of the rock at low tidal mark and in a burrow of sand beach at supra tidal mark, respectively. At present, E. smithi is the only species of the genus represented in Korean waters. Including the new records in this study, the established brachyuran fauna in Korea now comprises 203 species.

• Journal of Species Research
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• v.5 no.3
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• pp.381-384
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• 2016

Two marine amoebae Vannella bursella (Page, 1974) Smirnov et al., 2007 and Pseudoparamoeba sp. were encountered from marine coastal waters of Masan Bay and Garorim Bay (Korea), respectively. These species are described with uninterpreted records based on light-microscopy of living cells and reported taxonomically for the first time from Korea. Diagnostics of these species are as follows. Vannella bursella: size in vivo, $17-29{\mu}m$ long with flattened ovoid, semicircular locomotive forms. Pseudoparamoeba sp.: size in vivo, $10-15{\mu}m$ long with elongated locomotive forms, producing a few short conical pseudopodia from anterior hyaline zone.

• Animal Systematics, Evolution and Diversity
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• v.28 no.4
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• pp.317-321
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• 2012

Previously, 13 species in six genera of the subfamily Banchinae and 29 speices in 16 genera of the subfamily Pimplinae were known from Korea. In this paper, two species, Rynchobanchus minomensis (Uchida, 1933) and Theronia laevigata nigra Uchida, 1928 are new to Korea. Also, the genus Rynchobanchus is recorded for the first time in Korea. Only one species of Theronia, Theronia atalantae (Poda, 1761), was recorded from Korea by Uchida (1928). New Korean names proposed for these two species are "Eol-gul-ga-si-maep-si-beol" and "Geom-jeong-nap-jak-maep-si-beol" for the R. minomensis and T. laevigata nigra, respectively. A key to the species of Theronia, diagnosis and photographs of diagnostic characters of them are provided.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.6
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• pp.745-753
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• 1996

Taxonomic revision of the family Dasyatidae was studied on the basis of the specimens collected from the Korean coasts from June 1994 to January 1996. The family Dasyatidae of Korea was classified into 6 species in genus Dasyatis, and the key to species was proposed with their synonyms and distributions. Three new records from Korea were described and figured in detail: Dasyatis acutirostra Nishida and Nakaya, D. matsubarai Miyosi and D. sinensis (Steindachner). Most species of the Korean stingrays are shared with those of China and Japan.