• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.275-280
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• 1997

We have investigated the deposition characteristics of (Ni0.8Fe0.2)20Ag80 thin films as a function of chamber pressure and nitrogen flow rate with scanning electron microscopy(SEM), atomic force microscopy(AFM), XRD and $\alpha$-step. The deposition rate of these film is decreased with increasing the chamber pressure and the nitrogen flow rate. With raising the chamber pressure, the growth mode of thin film is changed from island growth to columnar one, which is probably due to energy of atom. Contrary, the nitrogen flow rate is raised, growth mode is changed from columnar to island one. According to the XRD patterns, the preferred orientation is inhibited as the nitrogen flow rate is kept above 10 sccm, but that is nearly independent on the chamber pressure. When the chamber pressure decrease or the nitrogen flow rate increase, phase separation into permoally and silver is occured.

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.4189-4200
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• 2021

In this study, the relationship between the environmental radiation dose rate and meteorological variables was investigated with multiple regression analysis and big data of those variables. The environmental radiation dose rate and 36 different meteorological variables were measured on Ulleung Island, Republic of Korea, from 2011 to 2015. Not all meteorological variables were used in the regression analysis because the different meteorological variables significantly affect the environmental radiation dose rate during different periods, and the degree of influence changes with time. By applying the Pearson correlation analysis and stepwise selection methods to the big dataset, the major meteorological variables influencing the environmental radiation dose rate were identified, which were then used as the independent variables for the regression model. Subsequently, multiple regression models for the monthly datasets and dataset of the entire period were developed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.814-824
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• 2020

Recently, public interest in air pollutants has increased, and the Korean government and local governments have attempted to improve air quality. This study examined the secondary air pollutant contribution in Ulleung Island, Jeju Island, and Baengnyeong Island and compared the differences between them by analyzing the air pollution level and weather conditions in these regions. The weather conditions of the island regions, such as wind speed, precipitation, and sunshine duration, and the average concentration of air pollutants, such as SO₂, NO₂, CO, O₃, PM₁₀, PM_2.5, were examined. The correlation coefficient between air quality factors of each island region and weather conditions was calculated. Regression analysis was conducted by setting primary air pollutants, SO₂, NO₂, and CO as independent variables, and secondary air pollutants, O₃, PM₁₀, and PM_2.5 as dependent variables to identify the regional contribution and impact. Therefore, the government and local governments should establish air quality management for each island region.

• Journal of the Korea Society of Computer and Information
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• v.26 no.8
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• pp.103-112
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• 2021

Gallbladder polyps (GBPs) may be a cause of gallbladder cancer. The known risk factors for GBPs are male gender, obesity, metabolic syndrome, and dyslipidemia. Especially, male gender has been known that it strongly affects on the prevalence of GBPs. Therefore, this study aimed to investigate risk factors affecting the prevalence of GBPs among adults on Jeju Island according to genders. We examined 5,574 subjects who visited a single health-screening center at Jeju National University Hospital between January 2015 and December 2019. Univariate and multiple logistic regression analysis were performed to identify risk factors affecting the prevalence of GBPs. The prevalence of GBPs were 8.9% in male subjects and 8.1% in female subjects, respectively. Multivariate analysis revealed that ≥60 year age (odds ratio [OR] 0.659; P=0.027) and aspartate aminotransferase >32 IU/L (OR 0.658; P=0.009) in male subjects and high-density lipoprotein-cholesterol ≥60 mg/dL (OR 0.514; P=0.013) in female subjects were independent factors affecting the prevalence of GBPs. The prevalence of GBPs in men (8.9%) is comparable to that in women (8.1%) on Jeju Island. Age <60 years and the higher level of aspartate aminotransferase in men and the normal or lower high-density lipoprotein-cholesterol in women were independent risk factors of GBPs on Jeju Island.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.7
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• pp.54-61
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• 2015

This paper presents short-term wind farm power forecasting method using multivariate analysis and time series. Based on factor analysis, the proposed method makes new independent variables which newly composed by raw independent variables such as wind speed, ramp rate, wind power. Newly created variables are used in the time series model for forecasting wind farm power. To demonstrate the improved accuracy, the proposed method is compared with persistence model commonly used as reference in wind power forecasting using data from Jeju Island. The results of case studies are presented to show the effectiveness of the proposed forecasting method.

• Journal of Digital Convergence
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• v.18 no.1
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• pp.111-119
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• 2020

This study takes Chinese independent tourists to South Korea as the research object, mines the data of tourists' digital footprints from online travel notes, and analyzes the characteristics of the tourism flow of Chinese independent tourists to South Korea by using the method of quantitative statistics and social network analysis(SNA). The results show that Seoul, Jeju Island, Busan and Daegu are the important tourist destinations for Chinese independent tourists entering South Korea. In addition, Qingdao, Tianjin, Shenyang, Hong Kong, Foshan and Macao are crucial hubs for Chinese independent tourists to visit South Korea. In future studies, the number of sample data should be increased. The time span of data collection should be extended for studying the annual variation characteristics of tourism flow and the trend of tourism hot spots.

• Korean Journal of Plant Resources
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• v.25 no.6
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• pp.719-730
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• 2012

This study was conducted to investigate the environmental characteristics of natural habitats, and the genetic variations in samples from 19 different quadrates of Asplenium scolopendrium 10 habitats. The natural habitats of A. scolopendrium were located at an altitudes 110-973 m with inclinations of $7-30^{\circ}$. All the quadrates were located on north facing slopes. The average field capacity of the soil is 31.4%, with organic matter at 16.7%, and the pH is 5.84. The soil texture was confirmed as sandy loam in 8 habitats and silt loam in 2 habitats. A total of 214 vascular plants were identified from 10 habitats. The importance value of the herbaceous layer (H) was the highest in A. scolopendrium, at 10.4%, followed by Arachniodes standishii (7.3%), Dryopteris crassirhizoma (6.5%), and Polystichum tripteron (5.3%), which implies that the natural habitats of A. scolopendrium are affinity with ferns. The species diversity of A. scolopendrium was estimated as on average 1.09, while the dominance and evenness were 0.12 and 0.87, respectively. The result of the RAPD analysis, among 59 bands amplified with a primer, 25 (42.4%) showed polymorphism. Twenty-one individuals of 10 habitats could be classified into four groups with similarity coefficient values ranging from 0.74 to 1.0. Mt. Mullae and Geumdaebong populations shows basal branching within the 21 individuals. Ulleung-do island and Jeju-do island population forms an independent clade, respectively. Mt. Moak and Byeonsan-bando clade formed a sister to the Ulleung-do island and Jeju-do island clade.

• Journal of IKEEE
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• v.23 no.1
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• pp.289-294
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• 2019

At present, domestic small islands mainly supply electric power using diesel generators. However, diesel generators can cause instability of the power system due to slow response on power load fluctuation, and cause environmental problems due to the emission of carbon gas by using fossil fuels. In order to overcome this problem, this paper proposes a method to establish an optimal microgrid by introducing solar power, wind power, and energy storage device to Chujado Island, which is supplied with electric power through a diesel generator. The economical optimum capacity of each distributed power source is calculated by using HOMER (Hybrid Optimization Model for Multiple Energy Resources) program and the proposed microgrid is validated by using PSCAD/EMTDC (Power Systems Computer Aided Design/ Electromagnetic Transients including DC) program which can analyze system stability.

• Journal of Microbiology and Biotechnology
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• v.28 no.1
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• pp.32-39
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• 2018

Samples of Laru (a fermentation starter) obtained from the upper part of Borneo Island were analyzed for their lactic acid bacteria (LAB) and fungal diversity using both a culture-independent method (PCR-DGGE) and culture-dependent methods (SDS-PAGE and MALDI-TOF MS). Pediococcus pentosaceus, Lactobacillus brevis, Saccharomycopsis fibuligera, Hyphopichia burtonii, and Kodamaea ohmeri were detected by all three methods. In addition, Weissella cibaria, Weissella paramesenteroides, Leuconostoc citreum, Leuconostoc mesenteroides, Lactococcus lactis, Rhizopus oryzae/Amylomyces rouxii, Mucor indicus, and Candida intermedia were detected by PCR-DGGE. In contrast, Lactobacillus fermentum, Lactobacillus plantarum, Pichia anomala, Candida parapsilosis, and Candida orthopsilosis were detected only by the culture-dependent methods. Our results indicate that the culture-independent method can be used to determine whether multiple laru samples originated from the same manufacturing region; however, using the culture-independent and the two culture-dependent approaches in combination provides a more comprehensive overview of the laru microbiota.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.170-176
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• 2009

Culture-independent 16S rDNA-DGGE profiling and phylogenetic analysis were used to examine the predominant bacterial communities associated with the two sponges, Dictyonella sp. and Spirastrella abata from Jeju island. The culture-independent approach involved extraction of total bacterial DNA, PCR amplification of the 16S ribosomal DNA using primer pair 341f-GC and 518r, and separation of the amplicons on a denaturing gradient gel. Denaturing gradient gel electrophoresis banding patterns indicated 8 and 7 bands from the two sponge species, Dictyonella sp. and Spirastrella abata, respectively. There were not common major bands in two different sponges. Comparative sequence analysis of variable DGGE bands revealed from 93% to 98% similarity to the known published sequences. The dominant bacterial group of Dictyonella sp. belonged to uncultured Gammaproteobacteria, while, that of Spirastrella abata belonged to uncultured Alphaproeobacteria and Firmicutes. DGGE analysis indicated predominant communities of the sponge-associated bacteria differ in the two sponges from the same geographical location. This result revealed that bacterial community profiles of the sponges were host species-specific.