• Korean Journal of Plant Taxonomy
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• v.45 no.4
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• pp.380-390
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• 2015

The morphological characters were observed in six taxa in the genus Dioscorea of Korea (D. polystachya, D. japonica, D. nipponica, D. quinqueloba, D. tenuipes, and D. dokoro). The underground structure and the formation of bulbil were useful characters for separating sect. Enanatiophyllum from sect. Stenophora. The important characters for discriminating taxonomic entities were as follows: the position of the anther and the shape of the pistil in the microstructural characters, including the protuberance of the base of the petiole, the shape and color of the flower, the shape of the fruit, and the shape of the seed wing. Based on the results, a key to Korean Dioscorea is provided and the distribution of these species in Korea is described.

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2362-2364
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• 2009

We report Pt hexapod nanoparticles with $6.4\;{\sim}\;9.7$ nm in size by a polyol process in the presence of PVP as a stabilizer and additive as a kinetic controller. The structure and morphology of Pt nanostructures are confirmed by field-emission transmission electron microscopy. The morphological control over platinum nanoparticles is achieved by varying the amount of seeds in the polyol process, where platinum precursor is reduced by ethylene glycol to form Pt nanoparticle at $150\;{^{\circ}C}$. As volume ratio between precursor-solution and seed-solution is increased from 10 to 50, the shape of Pt nanostructures is evolved from small seeds to tripod and hexapod. In addition, the size-controlled platinum hexapod nanostructures are successfully obtained using seeding method.

• Plant Resources
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• v.2 no.2
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• pp.127-132
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• 1999

This study was carried out to investigate the morphological characteristics of the plants and seeds of Ainsliaea acerifolia and to determine the optimum condition for producing sprouts from the seeds. Plant height, flower stalk length, and pod number were higher in natural habitat than in campus farm. Average 1.2 seeds per pod was set but only 0 to 2 seeds per plant was set in plants with the enveloped flower stalks, indicating that this is an outcrossing species. Most of seeds were 9-11mm long and 1.1-1.4mm wide. Fresh weight of seeds was ranged from 10mg to 17mg. Seeds germinated well at 15$^{\circ}C$ and 2$0^{\circ}C$. Mean germination period was 11.5 day at 15 to $25^{\circ}C$. Sprouts grown at 15$^{\circ}C$ was longest(5.4cm) and heaviest(738mg/10 sprouts). Chlorophyll content was 333mg per fresh weight 110g. Protein, Fe, vitamin Bl, vitamin B2, and vitamin C were respectively 23.7mg, 6.4mg, 1.82mg, 0.49mg, and 10..7mg.

• Korean Journal of Materials Research
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• v.30 no.8
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• pp.399-405
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• 2020

In the present investigation we show the effect of Al doping on the length, size, shape, morphology, and sensing property of ZnO nanorods. Effect of Al doping ultimately leads to tuning of electrical and optical properties of ZnO nanorods. Undoped and Al-doped well aligned ZnO nanorods are grown on sputtered ZnO/SiO₂/Si (100) pre-grown seed layer substrates by hydrothermal method. The molar ratio of dopant (aluminium nitrate) in the solution, [Al/Zn], is varied from 0.1 % to 3 %. To extract structural and microstructural information we employ field emission scanning electron microscopy and X-ray diffraction techniques. The prepared ZnO nanorods show preferred orientation of ZnO <0001> and are well aligned vertically. The effects of Al doping on the electrical and optical properties are observed by Hall measurement and photoluminescence spectroscopy, respectively, at room temperature. We observe that the diameter and resistivity of the nanorods reach their lowest levels, the carrier concentration becomes high, and emission peak tends to approach the band edge emission of ZnO around 0.5% of Al doping. Sensing behavior of the grown ZnO nanorod samples is tested for H₂ gas. The 0.5 mol% Al-doped sample shows highest sensitivity values of ~ 60 % at 250 ℃ and ~ 50 % at 220 ℃.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.12
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• pp.841-846
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• 2016

ZnO nanorods were grown on $SiO_2$ coated Si wafers and glass by the hydrothermal method. The structural and optical properties variation of ZnO nanorods as a function of growing time was studied. ~10 nm-thick ZnO thin films deposited on substrates by rf magnetron sputtering were employed as seed layers. Zinc nitrate hexahydrate (0.05 M) and hexamethylenetetramine (0.05 M) mixed in DI water were used as a reaction solution. ZnO nanorods were respectively grown for 30 min, 1 h, 2 h, 3 h, and 4 h by maintaining the reactor at $90^{\circ}C$. Crystallinity of ZnO nanorods was analyzed by X-ray diffraction, and the morphology of nanorods was observed by a field emission scanning electron microscope. Transmittance and absorbance were measured by a UV-Vis spectrophotometer, and energy band gap and urbach energy were obtained from the data. Photoluminescence measurements were carried out using Nd-Yag laser (266 nm).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.1
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• pp.44-49
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• 1995

Abstract The surface of 6H - SiC bulk crystal grown by sublimation process was investigated by optical microscope observation. Since, in the 6H crystal growing, the crystal had the habitual step growth attitude such that the lateral growth rate along the random a - axis orientation was higher than that along the c - axis of the growth direction, then many steps were developed. There were, also, many micropipes on the surface in the form of as-like large voids. However, they were differenciated with pores and cross- sectional shape of them were close to the circle. In this study, many micropipes, planar defects and the growth steps appeared on the grown crystal surface were investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.49-49
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• 2010

Nanopiezotronics is an emerging area of nanotechnology with a variety of applications that include piezoelectric field-effect transistors and diodes, self-powered nanogenerators and biosystems, and wireless nano/biosensors. By exploiting coupled piezoelectric and semiconducting characteristics, it is possible for nanowires, nanobelts, or nanorods to generate rectifying current and potential under external mechanical energies such as body movement (handling, winding, pushing, and bending) and muscle stretching, vibrations (acoustic and ultrasonic waves), and hydraulic forces (body fluid and blood flow). Fully transparent, flexible (TF) nanogenerators that are operated by external mechanical forces will be presented. By controlling the density of the seed layer for ZnO nanorod growth, transparent ZnO nanorod arrays were grown on ITO/PES films, and a TF conductive electrode was stacked on the ZnO nanorods. The resulting integrated TF nanodevice (having transparency exceeding 70 %) generated a noticeable current when it was pushed by application of an external load. The output current density was clearly dependent on the force applied. Furthermore, the output current density depended strongly on the morphology and the work function of the top electrode. ZnO nanorod-based nanogenerators with a PdAu, ITO, CNT, and graphene top electrodes gave output current densities of approximately $1-10\;uA/cm^2$ at a load of 0.9 kgf. Our results suggest that our TF nanogenerators are suitable for self-powered TF device applications such as flexible self-powered touch sensors, wearable artificial skins, fully rollable display mobile devices, and battery supplements for wearable cellular phones.

• Korean Journal of Plant Resources
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• v.34 no.3
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• pp.223-248
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• 2021

We conducted a taxonomic study and agricultural environmental risk assessments of 41 putative invasive alien plants designated by the Ministry of Environment in 2016. In order to achieve the goal, we carried out the field survey four times including the United States, Australia, and Mexico, and investigated specimens, literature, and other information including seed morphology, classification key, and habitat conditions. In this study, we reported the taxonomic characters, ecological risk, and weed risk assessment of 41 putative invasive alien plants, and suggested significant information about 11 species to contribute to establish solutions of regulation management for putative invasive alien plants - Spirodela punctata (G.Mey.) C.H.Thomps. (Araceae), Sagittaria graminea Michx. (Alismataceae), Elodea nuttallii (Planch.) H.St. John, Hydrocharis morsus-ranae L., Stratiotes aloides L. (Hydrocharitaceae), Eichhornia azurea (Swartz) Kunth, Monochoria hastata (L.) Solms (Pontederiaceae), Aegilops tauschii Coss. (Poaceae), Myriophyllum heterophyllum Michx. (Haloragaceae), Bunias orientalis L. (Brassicaceae), and Heracleum sosnowskyi Manden. (Apiaceae).

• International Journal of Industrial Entomology and Biomaterials
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• v.44 no.1
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• pp.12-20
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• 2022

In this research, the silk web was hot-pressed for various times, the effect of press time on the structure and mechanical properties of silk non-woven fabric was also investigated. The yellowing appeared in the silk non-woven fabric and became more apparent as press time was increased. The crystallinity of silk was decreased by the hot press treatment and it did not change significantly with an increase of hot press time. The porosity of silk non-woven fabric was constantly decreased until 120 s and it did not change much after that. The thickness of silk non-woven fabric was significantly decreased by a press time of 10 s and slightly decreased with a further increase of hot press time. The hot press treatment increased the maximum stress and elongation of silk non-woven fabrics. The press time had a significant impact on the mechanical properties of silk non-woven fabric, with 90 s being the optimum condition for the best work of rupture of silk non-woven fabric.

• Korean Journal of Environment and Ecology
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• v.24 no.1
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• pp.62-68
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• 2010

This study was conducted to find out how the germination, phenology and leaf morphology of Phytolacca insularis(endemic species of Korea) and P. americana(alien species) react to the global warming situation. Seed and seedlings of two species were sampled and placed under two separate conditions for the experiment. One of the seed and seedlings was treated in the glass house with control(ambient $CO_2$+ambient temperature, (AC-AT), and the other with control(elevated $CO_2$+ elevated temperature, EC-ET), over the period of one year, 2008-2009. The germination rate of two species was fast, and the time of their germination started early, when they were treated at EC-ET than at AC-AT. Furthermore, the germination rate of Phytolacca insularis(endemic species of Korea) was found to be comparatively lower than that of P. americana(alien species). The former showed only vegetative growth whereas the latter showed both vegetative growth and reproductive growth in one year period. The more $CO_2$ degree and temperature increased, phenological responses of two species, including leaf growth, the formation of flower stems, flowering, and fruit maturing, became much faster, and the time of their leaf-yellowing was delayed. The lamina length of P. insularis was not significantly affected by elevated $CO_2$ and temperature. The lamina length of P. americana, on the other hand, became longer at EC-ET than at AC-AT, but the leaf width of both species increased at EC-ET. As for the number of leaves, both species showed no difference. Finally, the ratio of the leaf area of P. insularis was high at AC-AT, but P. americana was high at EC-ET. These results indicate that P. americana, aliens species, reacts more sensitively to global warming than P. insularis, endemic species, does.