• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2010년도 한국우주과학회보 제19권1호
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• pp.30.2-30.2
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• 2010

It is a mistaken impression that the midlatitude ionosphere was a very stable region with well-known morphology and physical mechanism. However, the large disturbances of midlatitude ionospheric contents in response to global thermospheric changes during geomagnetic storms are reported in recent studies using global GPS TEC map and space-born thermospheric UV images, and its importance get higher with the increasing application areas of space navigation systems and radio communication which are mostly used in the midlatitudes. Positive and negative storm phases are used to describe increase and decrease of ionospheric electron density. Negative storms result generally from the enhanced loss rate of electron density according to the neutral composition changes which are initiated by Joule heating in high-latitudes during geomagnetic storms. In contrast, positive ionospheric storms have not been well understood because of rare measurements to explain the mechanisms. The large enhancements of ground-based GPS TEC in Korea were observed on 8 and 10 November 2004. The positive ionospheric storm was continued except for dawn on 8 November, and its maximum value is ~65 TECU of ~3 times compared with the monthly mean TEC values. The other positive phase on 10 November begin to occur in day sector and lasted for more than 6 hours. The O/N2 ratios from GUVI/TIMED satellite show ~1.2 in northern hemisphere and ~0.3 in southern hemisphere of the northeast Asian sector on 8 and 10 November. We suggest the asymmetric features of O/N2 ratios in the Northeast Asian sector may play an important role in the measured GPS TEC enhancements in Korea because global thermospheric wind circulation can globally change the chemical composition during geomagnetic storms.

• 한국도서관정보학회지
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• 제49권4호
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• pp.329-349
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• 2018

이 연구에서는 하와이대학교 해밀턴 도서관의 '스페셜 코리안 컬렉션(Special Korean Collecton)'에 주목하여 한국학 자료들의 실제적인 구축 현황을 살피고자 했다. 이 컬렉션에는 마샬 필(Marshall Pihl)의 희귀 도서와, 대학 기관인 '한국학센터(Center for Korean Studies)'가 수집한 자료들이 포함되어 있다. 본고에서는 이를 대상으로 첫째, 한국학 자료들의 실제적인 구축 현황은 어떠한가? 둘째, 학문 분야와 자료의 성격, 그 가치는 무엇인가? 등을 고찰하였다. 이러한 과정을 통해 자료적 가치를 해명하고, 한국학 자료 체계화의 필요성을 제기하였다, 이는 미주 지역뿐만 아니라 동북아시아, 러시아 및 중앙아시아 한국학 자료에까지 확산될 논의이기도 하다. 현재는 이주 초기 한국학 자료들에 대한 전반적인 검토가 부족한 상태라고 할 수 있다. 그 결과 연구사적으로 중요한 자료임에도 불구하고, 동포들의 학문 및 문학, 문화, 예술 등 각 분야에 걸친 자료들을 파악하지 못하고 있는 경우도 상당할 것으로 보인다. 결국 본고는 코리안 컬렉션의 체계화와 향후 방향성을 모색한 시론이라 할 수 있다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2019년도 춘계학술대회
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• pp.63-63
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• 2019

Tea plant (Camellia sinensis (L.) O. Kuntze) has been cultivated widely in many developing Asian, African, and South American countries, where it is the most widely consumed beverage in the world next to water. It has critical importance to understand the genetic diversity and population sturcutre for effective collection, conservation, and utilization of tea germplasm. In this study, 410 tea accessions collected from South Korea were analyzed using 21 SSR markers. Among 410 tea accessions, 85.4% (310 accessions) accessions were collected from Jeollanam-do. A total of 286 alleles were observed, and the genetic diversity and evenness were estimated to be averagely 0.79 and 0.61, respectively, across all the tested samples. Using discriminant analysis of principal components, the four clusters were detected in 410 tea accessions. Among them, cluster 1 showed higher frequency of rare alleles (less than 1%) than other clusters. Using calculation of the index of association and rbaD value, each cluster showed a clonal mode of reproduction. The result of AMOVA showed that most of the variation observed was within populations (99%) rather than among populations (1%). Our results might contribute to provide data about genetic diversity for the conservation of tea germplasm and for future breeding programs.

• Journal of Forest and Environmental Science
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• 제35권3호
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• pp.159-172
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• 2019

Madhupur National Park (MNP) is one of the last remaining patches of old-growth natural Sal forest left in Bangladesh where the forest is tropical moist deciduous type. A study was revealed to assess the tree species diversity and composition in this area. For determining tree species the study was conducted through extensive random quadrat survey methods with $20m{\times}20m$ sized plots. Results of the study indicated that there were 139 tree species belonging to 100 genera and 40 families. The quadrat survey assessed the basal area, stem density, diversity indices and importance value index of the tree species having ${\geq}5cm$ D.B.H (Diameter at Brest Height). The basal area and stem density of the tree species were $20.689{\pm}1.08m^2/ha$ and $1412.93{\pm}64.27stem\;ha^{-1}$ while, diversity indices, i.e. Shannon-Wiener's diversity, Simpson's evenness, Margalef's species richness and Pielou's dominance indices indicated poor diversity in comparison to that of other PAs (Protected Areas) in South-Eastern region of Bangladesh. The structural composition based on height and D.B.H through reverse-J shaped curve indicated higher regeneration and recruitment but removal of trees of large growth classes. Sal (Shorea robusta) was the most dominant tree species that accounts 75% of the total tree individuals in the natural forest patches. However, some associates of Sal, i.e. Bhutum (Hymenodictyon orixensis), Gadila (Careya arborea), and Kusum (Schleichera oleosa) etc. were seemed to be rare in MNP.

• 한국콘텐츠학회논문지
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• 제21권2호
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• pp.652-666
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• 2021

유튜브 채널에서 중국 관련 코로나19 정보의 확산과정을 네트워크 분석을 통해 알아봤다. 중국 관련 코로나19 정보를 사실 정보와 허위정보로 구분했고, 사실 정보는 긍정적, 부정적으로 분류했다. 네트워크 분석결과 부정적 정보와 허위정보가 많았고, 긍정적 정보는 가장 적었다. 허위정보 중에서 우한연구소 유출설 관련 동영상이 많았고, 유전자 조작설 관련 동영상의 조회 수와 매개 중심성 평균이 가장 컸다. 언론사 채널은 허위정보에 대한 팩트 체크보다 있는 그대로 전달하는데 그쳤다. 중국 관련 코로나19 동영상 중 부정적 정보와 허위정보가 많았다는 것은 중국 관련 비판적이거나 자극적인 내용이 유튜버의 관심을 끌었다는 것을 보여준다. 결론적으로 유튜브 채널의 허위정보는 이용자들이 유사한 주제의 동영상을 시청하게 하는 확산 효과를 가져왔다.

• Bulletin of the Korean Chemical Society
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• 제13권3호
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• pp.248-252
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• 1992

$ZrO_2-dopedYb_2O_3solid$ solutions containing 1, 3, 5, 7 and 9 mol% $ZrO_2were$ synthesized from spectroscopically pure $Yb_2O_3$ and $ZrO_2$ powders and found to be rare earth C-type structure by XRD technique. Electrical conductivities were measured as a function of temperatures from 700 to $1050^{\circ}C$ and oxygen partial pressures from 1${\times}$$10^-5$ to 2${\times}$ $10^-1$atm. The electrical conductivities depend simply on temperature and the activation energies are determined to be 1.56-1.68 $_eV$. The oxygen partial pressure dependence of the electrical conductivity shows that the conductivity increases with increasing oxygen partial pressure, indicating p-type semiconductor. The $PO_2$ dependence of the system is nearly power of 1/4. It is suggested from the linearity of the temperature dependence of electrical conductivity and only one value of 1/n that the solid solutions of the system have single conduction mechanism. From these results, it is concluded that the main defects of the system are negatively doubly charged oxygen interstitial in low. $ZrO_2doping$ level and negatively triply charged cation vacancy in high doping level and the electrical conduction is due to the electronic hole formed by the defect structure.

• 식물분류학회지
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• 제52권2호
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• pp.102-107
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• 2022

Rhododendron keiskei var. hypoglaucum (Ericaceae) was recently reported in Korea, with a disjunct distribution on the southern islands of the Korean Peninsula. Although chromosome numbers and ploidy variations are important traits in angiosperms, gaining a clear understanding the cytological features of Rhododendron has been hampered by the small size of its chromosomes. We herein report the chromosome number, karyotype structure, and genome size of R. keiskei var. hypoglaucum for the first time. The chromosome number of the investigated plants was 2n = 26 with x = 13 as the base chromosome number, which is the one of the frequently encountered base chromosome numbers in Rhododendron. The karyotype of R. keiskei var. hypoglaucum is composed of metacentric and submetacentric chromosomes similar in length, which ranged from 1.39 to 2.40 ㎛. The DNA 1C-value in all examined accessions was small, ranging from 0.63 to 0.65 pg, further supporting the stable genome size in Rhododendron. These comprehensive cytological results provide a framework for detailed molecular, cytogenetic, and phylogenomic analyses that can be used to interpret the slow species diversification rate in Rhododendron.

• Genomics & Informatics
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• 제19권4호
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• pp.42.1-42.17
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• 2021

Salivary gland carcinoma (SGC) is rare cancer, constituting 6% of neoplasms in the head and neck area. The most responsible genes and pathways involved in the pathology of this disorder have not been fully understood. We aimed to identify differentially expressed genes (DEGs), the most critical hub genes, transcription factors, signaling pathways, and biological processes (BPs) associated with the pathogenesis of primary SGC. The mRNA dataset GSE153283 in the Gene Expression Omnibus database was re-analyzed for determining DEGs in cancer tissue of patients with primary SGC compared to the adjacent normal tissue (adjusted p-value < 0.001; |Log2 fold change| > 1). A protein interaction map (PIM) was built, and the main modules within the network were identified and focused on the different pathways and BP analyses. The hub genes of PIM were discovered, and their associated gene regulatory network was built to determine the master regulators involved in the pathogenesis of primary SGC. A total of 137 genes were found to be differentially expressed in primary SGC. The most significant pathways and BPs that were deregulated in the primary disease condition were associated with the cell cycle and fibroblast proliferation procedures. TP53, EGF, FN1, NOTCH1, EZH2, COL1A1, SPP1, CDKN2A, WNT5A, PDGFRB, CCNB1, and H2AFX were demonstrated to be the most critical genes linked with the primary SGC. SPIB, FOXM1, and POLR2A significantly regulate all the hub genes. This study illustrated several hub genes and their master regulators that might be appropriate targets for the therapeutic aims of primary SGC.

• Journal of Radiation Protection and Research
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• 제46권2호
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• pp.58-65
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• 2021

Background: The evaluation of skyshine distribution, release of airborne radioactive nuclides, and soil activation and groundwater migration were required for radiological assessment of the impact on the environment surrounding In-Flight (IF)-system facility of the RAON (Rare isotope Accelerator complex for ON-line experiment) accelerator complex. Materials and Methods: Monte Carlo simulation by MCNPX code was used for evaluation of skyshine and activation analysis for air and soil. The concentration model was applied in the estimation of the groundwater migration of radionuclides in soil. Results and Discussion: The skyshine dose rates at 1 km from the facility were evaluated as 1.62 × 10^-3 μSv·hr^-1. The annual releases of ³H and ¹⁴C were calculated as 9.62 × 10^-5 mg and 1.19 × 10^-1 mg, respectively. The concentrations of ³H and ²²Na in drinking water were estimated as 1.22 × 10^-1 Bq·cm^-3 and 8.25 × 10^-3 Bq·cm^-3, respectively. Conclusion: Radiological assessment of environmental impact on the IF-facility of RAON was performed through evaluation of skyshine dose distribution, evaluation of annual emission of long-lived radionuclides in the air and estimation of soil activation and groundwater migration of radionuclides. As a result, much lower exposure than the limit value for the public, 1 mSv·yr^-1, is expected during operation of the IF-facility.

• 지질공학
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• 제32권2호
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• pp.295-310
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• 2022

월악산-속리산 화강암은 SiO₂와 알카리(Na₂O+K₂O) 함량이 높고 CaO와 P₂O₅는 결핍된 원소 특성을 보인다. 또한 화강암의 알루미나 포화지수는 1.3 이상으로 과알루미나질 특성을 보인다. U과 Th의 평균 함량은 각각 8.3과 39.3 ppm으로서 국내 중생대 화강암 중에서 가장 높은 방사성 원소 함량을 보이며, 화강암의 세계 평균보다 약 2배 정도로 높다. 이러한 높은 방사성 원소 함량 특성은 화강암의 고분화 특성과 대륙지각 기원의 암석 성인에 기인한다. U 또는 Th을 함유하는 방사성 광물은 저어콘, 토라이트, 모나자이트, 제노타임, 퍼구소나이트, 우라니나이트 등이다. 화강암의 Th/U 비 평균값이 5.4로서 지각 평균값과 유사하다는 것은 방사성 원소의 화강암 내 분포가 지각 기원 물질의 마그마 작용에 조절되었음을 의미한다. U과 Th에 대한 Zr, Y, HREE 간의 상관관계로 보아, 방사성 원소는 저어콘이나 모나자이트보다는 주로 제노타임에 포함되어 산출되는 것으로 해석된다.