• Journal of the Korean Ceramic Society
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• v.23 no.1
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• pp.67-73
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• 1986

SiC and $SiC-Si_3N_4$ powder were synthesized via the carbiding and carbiding-nitriding reaction of Jecheon quartz respectively using graphite as a reducing agent. $\beta$-SiC+($\alpha$+$\beta$)-$Si_3N_4$ composite was obtained by the carbiding-nitriding reaction of Jecheon quartz-graphite mixture at 1, 35$0^{\circ}C$ in $H_2$ atmosphere. $\beta$-SiC+($\alpha$+$\beta$)-$Si_3N_4$ composite was obtained by the carbidint-nitriding reaction of Jecheon quartz-graphite mixture at 1, 35$0^{\circ}C$ in $N_2-H_2$ atmosphere. The ratio of $\beta$-SiC+($\alpha$+$\beta$)-$Si_3N_4$ content in a produced composite could be controlled by adjusting the reaction time and gaseous mixture.

• Journal of Industrial Technology
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• v.30 no.A
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• pp.95-101
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• 2010

This paper is results of case study on characteristics of debris flow occurred at Jecheon during a heavy rainfall in 2009. The site studied is the mountain area located at Palsong-ri Bongyang-op in Jecheon-si where serious damages due to debris flow were occurred by heavy rainfall during July 7 to July 16 in 2009. Intensity and duration of rainfall causing debris flow were analyzed on the basis of AWS data. Characteristics of debris flow such as initiation, transportation and deposition were investigated through field reconnaissance. The geological and topographical characteristics of slope where debris flow was triggered were figured out and characteristics of erosion on the bottom and sides of valley during transportation of debris flow were also investigated. The slope and boundary of valley where the debris flow started to be deposited were studied.

• Journal of the Korean Ceramic Society
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• v.24 no.2
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• pp.139-146
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• 1987

${\beta}$-SiC powders were prepared by the simultaneous reduction and carbiding of Jecheon quartzite at 1400$^{\circ}C$ for 7 hours in hydrogen atmosphere, using graphite or carbon black as the reducing and carbiding reagent. The prepared SiC powder was acid-treated with the mixture of fluoric acid and hydrochloric acid at room temperature and also by heating on an alcohol lamp for one hour, respectively. The impurities were mostly eliminated and the purity of SiC became 98.5% after hot acid treatment. The specific surface area of SiC powder was also increased up to 115㎡/g by hot acid treatment. This pure and fine SiC powder was hot-pressed at 1900$^{\circ}C$ for 30min, using 5wt% Al2O3 as a sintering aid. The density, M.O.R., KIC and hardness of the hot-pressed SiC ceramics were 3.195g/㎤, 48.7Kgf/$\textrm{mm}^2$, 5.4MN/㎥/2 and 2,182Kgf/$\textrm{mm}^2$, respectively.

• Journal of the Korean Ceramic Society
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• v.51 no.2
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• pp.115-120
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• 2014

Quicklime(CaO) is generally obtained through the calcination of limestone, the main component of which is calcium carbonate($CaCO_3$). Quicklime generates high-temperature heat when reacting with water, forming slaked lime($Ca(OH)_2$). The industrial sectors for limestone are determined by the hydraulic activity of slaked lime, which is obtained by measuring temperature changes during the hydration reaction. Accordingly, this study examined the different crystallographic characteristics of limestone as affected by the geological origins of the regions where the limestones were produced, and how these characteristics affected hydraulic activity. Six limestone samples were collected from the Jecheon and Cheongsong areas and the hydraulic activities were measured in accordance with KS E 3077. The results indicate that limestone produced in the Cheongsong area, recrystallized through metamorphism caused by hydrothermal alteration, hada larger grain size of calcite than that of the Jecheon area, and displays a tendency of changing to marble. Limestone from the Cheonsong area showed more radical reaction in the early stage of hydration compared to that ofthe Jecheon area. In addition, it was revealed that limestone having more impurities like $SiO_2$ have lower hydraulic activity.

• The Journal of the Korea Contents Association
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• v.2 no.1
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• pp.24-31
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• 2002

The purpose of this study is development of the management and guide system for convenient use of new address guide system for systematic management and use of spatial information gained by management of numerical map of building and road to large basic new address, survey and input of main gate, setting up the road session, naming and input of road name, grant of given number of building, new address guide, life GIS and added information on Web-site in Jecheon-si city area In this study, development and establishment of new address management and guide system in local cities are designed by making full use of GIS function of client server base. A guide system is designed the same database as management system, and it is transformed into Web-GIS environment and developed in order to add the various functions of life GIS as wet as new address guide. In the result, the effectiveness of new address system and guide of Jecheon-si city could be highly increased owing to not only citizens'easy access but also easy availability of various informations necessary in life by developed its system.

• Journal of the Society of Disaster Information
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• v.11 no.1
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• pp.23-34
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• 2015

This Study analyzed heavy snow properties according to the area that was based by winter weather properties and the damage data by the heavy snow among each local government of Chungcheongbuk-do. The result of analysis, Jecheon-si and Boeun-gun are represented the highest dangerous regions by potential degree of risk by average amount of snowfall for 35 years. But, the potential degree of risk by maximum amount of snowfall for 35 years is different with it. Cheongju-si and Youngdong-gun, Goesan-gun, Boeun-gun are represented the highest dangerous regions. Examining the frequency of regions with potential danger factors according to the characteristics of heavy snowfall, Boeun-gun and Jecheon-si, Goesan-gun, Youngdong-gun, Cheongju-si is derived the highest dangerous regions in Chungcheongbuk-do.

• Korean Journal of Environment and Ecology
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• v.19 no.1
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• pp.31-45
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• 2005

This study was carried out to investigate the vascular plants of the construct-reserved sites of ecological forests in Deokdong-ri, Baekwoon-myeon, Jecheon-si, and Chungcheongbuk-do, Korea and the period was from March to October, 2004. The results of surveying the vascular plants were recorded as 371 taxa; 83 families, 238 genera, 324 species, 44 varieties and 3 forma. There were 4 species of rare and endangered plants as designated by Korea Forest Service; Eranthis stellata, Paeonia japonica, Viola albida and Scopolia japonica. There were 9 species of Koreanendemic plants Pseudostellaria coreana, Melandryum seoulense, Clematis trichotoma, Deutzia coreana, Spiraea prunifolia for. simpliciflora, Ajuga spectabilis, Weigela subsessilis, Cirsium setidens and Saussurea nutans. Ten species of naturalized plants were observed Panicum dichotomiflorum, Rumex crispus, Amaranthus retroflexus, Lepidium apetalum, Trifolium repens, Oenothera Jamayckiana, Erigeron annuus, Erigeron canadensis, Bidens frondosa and Taraxacum officinale. In the results of analysis by floristic region, the specific plants were summarized as 52 taxa; 30 families, 47 genera, 49 species and 3 varieties.

• Journal of the Korean Association of Geographic Information Studies
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• v.4 no.3
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• pp.13-20
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• 2001

The purpose of this study is development of the management and guide system for convenient use of new address guide system for systematic management and use of spatial information gained by mapping of numerical map of building and road to large basic new address, survey and input of main gate, decision of the road session, naming and input of road name, grant of numbering of all houses and buildings, new address guide, real life geographical information and added information service on web site in Jecheon-si city area. In this study, the development and establishment of new address management and guide system in local cities are designed by making full use of GIS function of client server based system. A guide system is designed the same database as management system, and it is transformed into Web GIS environment and developed in order to add the various functions of life GIS as well as new address guide. In the result, the effectiveness of new address system and guide of Jecheon-si city could be highly increased owing to not only citizens' easy access but also easy availability of various informations necessary in life by developed its system.

• The Korean Journal of Mycology
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• v.52 no.2
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• pp.135-143
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• 2024

Lindera obtusiloba Blume, a shrub prevalent in the understory vegetation of the deciduous forests in East Asia and Korea, is known for its pharmacological properties, including antioxidant, anti-allergic, and anti-inflammatory activities. Endophytic fungi were isolated from surface-sterilized twigs and leaves of L. obtusiloba collected from Samcheok-si and Jecheon-si in Korea. The fungal strains were identified based on their morphological characteristics and molecular analyses using DNA markers such as internal transcribed spacer, large subunit rDNA, β-tubulin, chitin synthase, and glyceraldehyde-3-phosphate dehydrogenase. Here, we report two new records of endophytic fungi isolated from L. obtusiloba in Korea: Colletotrichum citricola and Valsa ceratophora. These results enhance our understanding of the diversity of endophytic fungi in L. obtusiloba and contribute to enhancing our knowledge of fungal biodiversity in Korea.

• Parasites, Hosts and Diseases
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• v.59 no.3
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• pp.319-324
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• 2021

Incidence of tsutsugamushi disease (scrub typhus) caused by Orientia tsutsugamushi, is steadily increasing. It is a mite-borne disease transmitted by chigger mites. In this study, the chigger mites were collected from field small mammals in Hwaseong-si (city), Gyeonggi-do (province), Korea, 2019 and 2020. The field small mammals captured were 56 Apodemus agrarius (94.9%) and 3 Crocidura lasiura (5.1%). A total of 7,531 chigger mites were collected from the captured small mammals. Using PCR test, 153 chigger mite pools were examined and 17 pools were reported positive for O. tsutsugamushi. The O. tsutsugamushi were identified to 5 strains; Jecheon strain was most prevalent, followed by Boryong strain. The other strains were OI011, Taguchi, and Shimokoshi. Collectively, these results provide essential regional information on mite-borne tsutsugamushi disease in the Hwaseong-si, and further contribute to bring awareness and rapid diagnosis for the tsutsugamushi disease.