• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.20 no.4
• /
• pp.195-200
• /
• 2020

With the growing interest in fossil fuel depletion and environmental pollution, railroad cars operating in Korea are in progress as the conversion from diesel to electric vehicles expands. The photovoltaic system, which is applied as an example of the conversion of electric vehicles, is infinite and pollution-free, and can produce energy without generating hazards such as air pollution, noise, heat, and vibration, and maintain fuel transportation and power generation facilities. There is an advantage that is rarely needed. However, the amount of electricity produced depends on the amount of solar radiation by region, and the energy density is low due to the power generation of about 25㎡/ kWp, so a large installation area is required and the installation place has limited problems. In view of these problems, many studies have been applied to fuel cells in the railway field. In particular, the plan to link the fuel cell power generation system railroad power supply system must be linked to the power supply system that supplies power to the railroad, unlike solar and wind power. Therefore, it has a close relationship with railroad cars and the linkage method can vary greatly depending on the system topology. Therefore, in this paper, we study the validity through simulation modeling related to linkage analysis according to system topology.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.241-241
• /
• 2008

Macrofore formation in silicon and other semiconductors using electrochemical etching processes has been, in the last years, a subject of great attention of both theory and practice. Its first reason of concern is new areas of macropore silicone applications arising from microelectromechanical systems processing (MEMS), membrane techniques, solar cells, sensors, photonic crystals, and new technologies like a silicon-on-nothing (SON) technology. Its formation mechanism with a rich variety of controllable microstructures and their many potential applications have been studied extensively recently. Porous silicon is formed by anodic etching of crystalline silicon in hydrofluoric acid. During the etching process holes are required to enable the dissolution of the silicon anode. For p-type silicon, holes are the majority charge carriers, therefore porous silicon can be formed under the action of a positive bias on the silicon anode. For n-type silicon, holes to dissolve silicon is supplied by illuminating n-type silicon with above-band-gap light which allows sufficient generation of holes. To make a desired three-dimensional nano- or micro-structures, pre-structuring the masked surface in KOH solution to form a periodic array of etch pits before electrochemical etching. Due to enhanced electric field, the holes are efficiently collected at the pore tips for etching. The depletion of holes in the space charge region prevents silicon dissolution at the sidewalls, enabling anisotropic etching for the trenches. This is correct theoretical explanation for n-type Si etching. However, there are a few experimental repors in p-type silicon, while a number of theoretical models have been worked out to explain experimental dependence observed. To perform ordered macrofore formaion for p-type silicon, various kinds of mask patterns to make initial KOH etch pits were used. In order to understand the roles played by the kinds of etching solution in the formation of pillar arrays, we have undertaken a systematic study of the solvent effects in mixtures of HF, N-dimethylformamide (DMF), iso-propanol, and mixtures of HF with water on the macrofore structure formation on monocrystalline p-type silicon with a resistivity varying between 10 ~ 0.01 $\Omega$ cm. The etching solution including the iso-propanol produced a best three dimensional pillar structures. The experimental results are discussed on the base of Lehmann's comprehensive model based on SCR width.

• Molecules and Cells
• /
• v.39 no.4
• /
• pp.352-357
• /
• 2016

Vertebrate neurogenesis requires inhibition of endogenous bone morphogenetic protein (BMP) signals in the ectoderm. Blocking of BMPs in animal cap explants causes the formation of anterior neural tissues as a default fate. To identify genes involved in the anterior neural specification, we analyzed gene expression profiles using a Xenopus Affymetrix Gene Chip after BMP-4 inhibition in animal cap explants. We found that the xCyp26c gene, encoding a retinoic acid (RA) degradation enzyme, was upregulated following inhibition of BMP signaling in early neuroectodermal cells. Whole-mount in situ hybridization analysis showed that xCyp26c expression started in the anterior region during the early neurula stage. Overexpression of xCyp26c weakly induced neural genes in animal cap explants. xCyp26c abolished the expression of all trans-/cis-RA-induced posterior genes, but not basic FGF-induced posterior genes. Depletion of xCyp26c by morpholino-oligonucleotides suppressed the normal formation of the axis and head, indicating that xCyp26c plays a critical role in the specification of anterior neural tissue in whole embryos. In animal cap explants, however, xCyp26c morpholinos did not alter anterior-to-posterior neural tissue formation. Together, these results suggest that xCyp26c plays a specific role in anterior-posterior (A-P) neural patterning of Xenopus embryos.

• Proceedings of the Botanical Society of Korea Conference
• /
• 1994.09a
• /
• pp.29-39
• /
• 1994

Serious issues about the changes in the environmental conditions on earth associated with human activities have arisen, and the interest in these problems has increased. It is urgent to determine how the expansion of terrestrial UV-B radiation due to the stratospheric ozone depletion influences living matters. In this connection, we have been investigating the effects of UV-B radiation on the growth of rice cultivars (Oryza sativa L.). We report here some physiological and genetic aspects of resistance to inhibitory effects of UV-B radiation on growth of rice cultivars as described below. Elevated UV radiation containing large amount of UV-B and a small amount of UV-C inhibited the development of plant height, the photosynthetic rate and the chlorophyll content in rice plants in a phytotron. Similar results were obtained in experiments, in which elevated UV-V radiation. Similar results were obtained in experiments, in which elevated UV-B radiation (transmission down to 290 nm) was applied instead of UV-B radiation containing a small amount of UV-C. The inhibitory effects of UV radiation was alleviated by the elevated CO2 atmospheric environment or by the exposure to the high irradiance visible radiation. The latter suggested the possibility that the resistance to the effects of UV radiation was either due to a lower sensitivity to UV radiation or to a greater ability to recover from the injury caused by UV radiation through the exposure to visible radiation. The examination of cultivar differences in the resistance to UV radiation-caused injuries among 198 rice cultivars belonging to 5 Asian rice ecotypes (aus, aman, boro, bulu and tjeleh) from the Bengal region and Indonesia and to Japanese lowland and upland rice groups showed the following: Various cultivars having different sensitivities to the effects of UV radiation were involved in the same ecotype and the same group, and that the Japanese lowland rice group and the boro ecotype were more resistant. Among Japanese lowland rice cultivars, Sasanishiki (one of the leading varieties in Japan) exhibited more resistance to UV rakiation, while Norin 1 showed less resistance, although these two cultivars are closely related. It was thus indicated that the resistance to the inhibitory effects of UV radiation of rice cultivars is not simply due to the difference in the geographical situation where rice cultuvars are cultivated. Form the genetic analysis of resistance to the inhibitory effects of UV radiation on growth of rice using F2 plants generated by reciprocally crossing Sasanishiki and Norin 1 and F3 lines generated by self-fertilizing F2 plants, it was evident that the resistance to the inhibitory of elebated UV radiation in these rice plants was controlled by recessive polygenes.

• Journal of Ginseng Culture
• /
• v.4
• /
• pp.13-37
• /
• 2022

Even before recorded history, the Korean people took ginseng. Later, poetry passed down from China developed into a literary style in which intellectuals from the Silla, Goryeo, and Joseon Dynasties expressed their thoughts concisely. The aim of this paper is to find Korean poems related to ginseng and to look for their semantic network. To this end, "Korea Classical DB ", produced by the Institute for the Translation of Korean Classics, was searched to find ginseng poems. As the result of a search in November 2021, two poems from the Three Kingdoms Period, two poems from the Goryeo Dynasty, and 23 poems from the Joseon Dynasty were searched. An examination of these poems found that the first ginseng poem was "Goryeoinsamchan," which was sung by people in Goguryeo around the 6th century. Ginseng poetry during the Goryeo Dynasty is represented by Anchuk's poem. Anchuk sang about the harmful effects of ginseng tributes from a realistic point of view. Ginseng poetry in the Joseon Dynasty is represented by Seo Geo-jeong in the early period and Jeong Yakyong in the late period. Seo Geo-jeong's ginseng poem is a romantic poem that praises the mysterious pharmacological effects of ginseng. A poem called "Ginseng" by Yongjae Seonghyeon is also a romantic poem that praises the mysterious medicinal benefits of ginseng. As a scholar of Realist Confucianism, Dasan Jeong Yak-yong wrote very practical ginseng poems. Dasan left five ginseng poems, the largest number written by one poet. Dasan tried ginseng farming himself and emerged from the experience as a poet. The story of the failure and success of his ginseng farming was described in his poems. At that time, ginseng farming was widespread throughout the country due to the depletion of natural ginseng and the development of ginseng farming techniques after the reign of King Jeongjo. Since the early 19th century, ginseng farming had been prevalent on a large scale in the Gaeseong region, and small-scale farming had also been carried out in other regions. What is unusual is Kim Jin-soo's poem. At that time, in Tong Ren Tang, Beijing (the capital of the Qing Dynasty), ginseng from Joseon sold well under the "Songak Sansam" brand. Kim Jin-Soo wrote about this brand of ginseng in his poem. In 1900, Maecheon Hwanghyeon also created a ginseng poem, written in Chinese characters. Thus, the semantic network of Korean ginseng poems is identified as follows: 1) Ginseng poetry in the spirit of the people - Emerging gentry in the Goryeo Dynasty (Anchuk). 2) Romantic ginseng poetry - Government School in the early Joseon Dynasty (Seo Geo-jeong, Seonghyeon, etc.). 3) Practical ginseng poetry - Realist School in the late Joseon Dynasty (Jeong Yak-yong, Kim Jin-soo, Hwang Hyun, etc.). This semantic network was extracted while examining the development of Korean ginseng poems.