• Animal Systematics, Evolution and Diversity
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• v.39 no.4
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• pp.289-294
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• 2023

We discovered a halacarid mite species, Isobactrus tuberculatus Abé, 1996, inhabiting marine plastic debris on the coast of Jeju Island, Korea. The key characteristics of these Korean specimens were consistent with those in the original description of specimens from Hokkaido, Japan, including the presence of tuberculate membranous cuticles between the anterior and posterior dorsal plates, fusion of the posterior epimeral plates I and II, tibia II with a bipectinate seta, tibiae III and IV each with five setae, and a pair of subgenital setae in females. However, two small morphological differences were noted: the distance between the anterior and posterior dorsal plates was shorter than that in Japanese specimens, and the location of dorsal seta-2 was closer to the anterior dorsal plate in Korean specimens. We herein provide detailed illustrations of I. tuberculatus, based on the Korean specimens, with a brief taxonomic comment on the similarities among allied congeneric species. The genus Isobactrus is first reported in Korea.

• Animal Systematics, Evolution and Diversity
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• v.40 no.1
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• pp.42-46
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• 2024

Two species from the genus Escharoides Milne Edwards, 1836, E. biseriatata and E. buffonellarioides n. sp. Were first found in Korean waters in this study. Their colonies were collected from two locations in the South Sea, Korea: Tongyeong Marine Ranch in 2004 and Daebyeon Port in 2009. Escharoides biseriatata shows a difference in the position of avicularia from the Chinese specimens. While avicularia are lateral to the orifice in Chinese specimens, the ones in Korean specimens seem to be located more latero-proximally. Since Escharoides biseriatata was reported as fouling bryozoans in China in 2001, this species first occurred at Daebyeon Port in Korea in this study. Escharoides buffonellarioides n. sp. is similar to E. adeonelloides in morphological features of zooids but is clearly distinguished by having the erect colonial form of small masses. With the addition of two species reported herein, four Korean Escharoides are recorded: E. biseriatata, E. buffonellarioides, E. excavata, and E. sauroglossa.

• Animal Systematics, Evolution and Diversity
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• v.40 no.3
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• pp.157-166
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• 2024

A new oenonid polychaete, Arabella turbidiricolor sp. nov., collected from intertidal zone along the coasts of eastern, western, and southern Korea is described. In Korea, this new species might have been confused with Arabella iricolor(Montagu, 1804), the type species of the genus, in having the following characteristics: ventralmost chaeta tapering gradually to guard, MI left robust and right gracile, MII right long, MV both with one tooth and posterior postchaetal lobe shorter than chaetae. However, A. turbidiricolor sp. nov. is readily distinguished from the latter by the following features: ventral maxillary carriers longer than or equal to dorsal, MI both distally falcate, and pygidium with two swollen pads. We provide detailed descriptions and illustrations for the new species in the present study. Also, morphological characteristics of known Arabella species are compared and discussed with a key to them.

• Archives of Metallurgy and Materials
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• v.65 no.4
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• pp.1323-1327
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• 2020

In this paper, we have studied the evolution of morphology and brazing behavior of Ag-28Cu alloy filler processed by high energy ball milling. The milling of the powder mixture was carried out for 40 h. The structural and morphological analyses were performed by the X-ray diffraction and scanning electron microscopy. The melting temperature of the braze filler was determined by differential thermal analysis. The filler wetting properties were assessed from the spread area ratio measurements on various Ti substrates. The results indicate that the ball milling can effectively depress the filler melting point and enhance the brazeability. The milled powder mixture showed Ag(Cu) solid solution with a crystallite size of 174-68 nm after 40 h. It was shown that the high energy ball milling can be a potential method to develop low temperature brazing fillers for advanced microjoining applications.

• Journal of Korean Society of Forest Science
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• v.67 no.1
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• pp.1-9
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• 1984

Taxonomical studies of the genus Acer in Korea (8 species, 3 varieties and 1 forma) were studied by the morphological characteristics of stipules. The results obtained were summarized as follows; 1) The stipules of the genus Acer were arranged oppositely with 4 - 10 stipules consisting of simple leaf, compound leaf and unifoliate compound leaf. The venation of stipules were cladodromous, basal reticulate, fibrous and palmately netted vein. The trichoma of stipules were glandula hair, glandular pubescent, sericeous, pilous, vinous, velutinous, tomentose, ciliate and lanate. As the morphological characteristics of stipules in the genus Acer established a strong point in the identification of species. 2) The species in the genus Acer in Korea were classified into six groups; (1) ginnala group (A. ginnala), (2) koreanum group (A. koreanum, A. japonicum, A. pseudosieboldianum var. koreanum), (3) mono group (A. mono, A, palmatum var. sanguineum, A. palamtum var. dissectum, A. palmatum var. dissectum f. aosidare), (4) negundo group (A. negundo), (5) palmatum group (A. palmatum), (6) platanoides group (A. platanoides, A. truncatum) by the morphological characteristics of stipules, 3) The stipules of platanoides group and negundo group were the least evolved types among the species in the genus Acer. 4) The stipules in the genus Acer were made the inner buds that were metamorphosed to the protected functional aspect by the evolution of petiols.

• Korean Journal of Plant Taxonomy
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• v.33 no.4
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• pp.373-386
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• 2003

Internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA were determined for 14 individuals representing eight taxa from Scopolia s. str. and related genera, Anisodus and Atropanthe. We found that the ITS sequences of Korean endemic species, S. parviflora, are significantly different from its allied species, S. japonica. This is contradictory to traditional taxonomic treatments in which those species are regarded as conspecific. S. parviflora exhibited closer relationship to S. carniolica, which is disjunctly distributed in Europe. In spite of substantially high sequence divergence between S. japonica and S. parvlflora/S. carniolica clade, morphological resemblance is evident among the species. Morphological stasis concept (retardation of morphological differentiation or evolution of similar characters among the disjuncts in a similar ecological habitat) was referred to understand this rather unusual evolutionary feature. S. lutescens, another Korean endemic species, shared almost identical ITS sequences with S. parviflora. Lack of diagnostic character distinguishing the taxa suggests that they are conspecific. Anisodus carniolicoides, which was originally described in Scopolia, was grouped with A. luridus and A. tanguticus. The monophyletic Anisodus formed a sister group relationship with a monotypic genus Atropanthe.

• Journal of the Korean Vacuum Society
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• v.16 no.1
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• pp.15-22
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• 2007

We present the morphological evolution at different source powers in the ion-enhanced etching of GaAs(100) in $BCl_3-Cl_2$ plasma. With little ion bombardment at floating potential, the surface develops <110< ridges and {111} facets, as it does in purely chemical etching. The morphology develops in less than 1 minute and grows bigger over time. The etched surfaces show different morphologies at different source powers with constant pressures of gases. Lowe. source power (100 W) produces poorly developed crystallographic surfaces while higher source power (900 W) produces well developed crystallographic surfaces. This is attributed to the availability of excited reactive species(chlorine atoms) depending on source powers. With more concentration of the reactive species at higher source powers, the surface of GaAs(100) would be a surface that is expected from thermodynamics while the surface morphology would be determined by sputtering in the lack of reactive species. Statistical analysis of the surfaces, based on scaling theory, revealed two spatial exponents: one(smaller than one) is formed by atomic scale mechanisms, the other(larger than one) is formed by larger scale mechanisms which is believed to develop facets.

• Korean Journal of Plant Taxonomy
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• v.39 no.1
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• pp.35-41
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• 2009

Astilbe (Saxifragaceae) is a genus well known for its disjunctive distribution in Asia and eastern North America. In this study, we reconstructed a molecular phylogeny of the genus using the sequences of ITS regions of nuclear ribosomal DNA. A total of 17 species representing major lineage of Astilbe and closely related taxa were included in the phylogenetic analyses. We obtained a Bayesian phylogenetic tree in which Saxifragopsis was positioned as a sister group to Astilbe. The Japanese endemic species, A.platyphylla was the most basal lineage within the genus. This species is well known for its distinct morphological features such as unisexual flowers, apetaly, and calyx with 7-11 lobes. Two species, A. biternata, a New World representative of the genus, and A. rivularis widely distributed in S. Asia, branched off early in the evolution of Astilbe. The remaining species formed a strongly supported core clade, which diverged into two robust geographical lineages: the first ("Japonica" clade) of species distributed in Japan, Taiwan, and Philippines and the other ("Rubra" clade), of taxa in China and Korea. The ITS phylogeny indicates that the Bering land bridges were the major route for the origin and dispersal of A. biternata. The two Taiwanese taxa and A. philippinensis were found to derive from the Japanese member, as the genus advanced southwards. The ITS phylogeny suggests that apetaly originated independently at least two times within the genus. Our results do not support Engler's classification system of the genus based on the leaf type (simple vs. compound), but reaffirm Hara's taxonomic idea which primarily considered the features of calyx.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.4
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• pp.244-252
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• 1994

The morphological changes of primary solid particles as a fuction of process time on Al-Si alloys during semi-solid state processing with a shear rate of 200s were studied. In hypereutectic Al-15.5wt%Si alloy, it was observed that primary Si crystals are fragmented in the early stage of stirring and morphologies of primary Si crystals change from faceted to spherical during isothermal shearing for 60 minutes. In quaternary Al-12.5wt%Si-2.9wt%Cu-0.7wt%Mg alloy system, it was observed both primary silicon and ${\alpha}$-alumunum particles. Microstructural evolution of primary Si crystals was similar to that of the hypereutectic Al-Si alloy but equiaxed ${\alpha}$-Al dendrites are broken into nearly spherical at the early stage of shearing and later stage of the isothermal shearing ${\alpha}$- Al particles are slightly coarsoned by Ostwald ripening. Mechanical properties of Al-Si-Cu-Mg alloy were compared to those from other processes (squeeze casting and gravity casting). After T6 heat treatment, comparable values of hardness were obtained while slightly lower compressive strength values were observed in rheocast alloy. The elongation, on the other hand, exhibited significant increasement of 15% over gravity cast alloy.

• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.347-351
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• 2020

A material changes its physical and chemical properties through the interaction with radiation and also the neutrons, which is electronically neutral so that the penetration depth is relatively deeper than that of other radioactive way including alpha or beta ray. Therefore, the radiation damage by neutron irradiation has been intensively investigated for a long time with respect to the safety of nuclear power plants. The damage induced by neutron irradiation begins with the creation of point defects in atomic scale in the unit of picoseconds, and their progress pattern can be characterized by microstructural defects, such as dislocation loops and voids. Their morphological characteristics affect the properties of neutron-irradiated materials, therefore, it is very important to predict the microstructure at a given neutron irradiation condition. This paper briefly reviews the evolution of radiation damage induced by neutron irradiation and introduces a phase-field model that can be widely used in predicting the microstructure evolution of irradiated materials.