• Korean Journal of Food Science and Technology
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• v.51 no.6
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• pp.543-550
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• 2019

In this study, volatile compounds in 13 aged and 3 commercial rice-distilled soju samples were isolated by headspace solid phase microextraction (HS-SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 85 volatile components including 35 esters, 15 alcohols, 5 ketones, 3 aldehydes, 15 miscellaneous, and 14 unknowns were identified. Esters and alcohols were the largest groups among the quantified volatiles. Differences in volatile compounds among the distilled soju samples and possible sample groupings were examined by principal component analysis of the GC-MS datasets. The first and second principal components (PC1 and PC2, respectively) explained 51.94% of the total variation across the 16 samples. The samples aged in oak containers had higher concentrations of ketones, aldehydes, and miscellaneous compounds. In the positive direction of PC1, oak-aged samples were observed, while, pot-aged samples were observed on the far negative side. Furthermore, samples aged for longer periods, such as 18 months, were observed in the positive direction of PC2.

• Korean Journal of Plant Resources
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• v.34 no.1
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• pp.79-88
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• 2021

This research was conducted to investigate the genetic diversity and select useful accession with agronomic characteristics of garlic (Allium sativum L.). germplasms at Garlic Research Institute in Chungbuk Agricultural Research and Extension Service. Morphological diversity and relationships among 160 germplasms collected from 26 countries were assessed by methods of clustering and principal component analysis. Among 11 types of leaves and bulbs characteristics, emergence days of leaf showed the highest variation with coefficient of variation of 84.8%, and the bulb weight and the number of scales showed higher variability with 24.3%. Correlation analysis based on 11 quantitative traits showed that bulb weight and bulb length have very high positive correlation with bulb quantity. Plant height, leaf length, and number of leaves showed positive correlation with bulb weight as collections with better performance in growth produced large bulb with higher quality. The cluster analysis based on 5 principal components generated 6 clusters with an average distance of 1.6 among clusters. Domestic genetic resources were the largest with 36 species (22.5%) in group II.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.3
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• pp.175-185
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• 2018

The aim of this study was to evaluate the variation of growth and quality characteristics in colored rice from 178 accessions and to develop useful, basic rice breeding data by classifying these germplasm characteristics via principal component (PC) analysis. The coefficient of variation of the 178colored rice accessions were the highest for panicle length (PL) and protein contents, followed by length-width ratio (LWR), 1000-grain weight (TGW), culm length (CL), and amylose contents, whereas the lowest was for the number of panicles per hill (NP), which is a yield component. The results from the PC analysis exhibited eigenvalues and contributions respective to each PC as follows: PC1, 2.06 and 29.49%; PC2, 1.31 and 18.75%; PC3, 1.21 and 17.36%; PC4, 1.01 and 14.38%. The eigenvalues of four PCs were over 1.0, and their cumulative contributions were 79.98%, which completes the necessary condition for evaluation of the 178 colored rice accessions. Cluster analysis showed cluster I as the largest, which included 79 accessions, while clusters II, III, IV, V, VI, and VII comprised 46, 19, 13, 4, 8, and 9 accessions, respectively. Moreover, dark brown accessions were dispersed in clusters I and II, and many resources of purple seed coat color were found in clusters V, VI, and VII. Particularly, cluster V had resources of only black and purple seed coat colors. Resources of cluster VII were found to have a relatively small average CL, PL, and LWR; notably, cluster V had the smallest average TGW, and cluster IV the lowest NP but the highest TGW. Finally, considering the yield potential, growth characteristics, heading stage, and color during breeding of colored rice, we obtained the following conclusions: cluster VII is suitable for breeding of colored rice; cross breeding among clusters I, II, and VII has a high yield potential; and it is possible to produce a superior color by cross breeding plants from cluster V and VI.

• The Journal of Engineering Geology
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• v.28 no.3
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• pp.465-473
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• 2018

The application of singular value decomposition (SVD) filtering is examined for attenuation of the ground-roll in land seismic data. Prior to the SVD computation to seek singular values containing the highly correlatable reflection energy, processing steps such as automatic gain control, elevation and refraction statics, NMO correction, and residual statics are performed to enhance the horizontal correlationships and continuities of reflections. Optimal parameters of SVD filtering are effectively chosen with diagnostic display of inverse NMO (INMO) corrected CSP (common shot point) gather. On the field data with dispersion of ground-roll overwhelmed, continuities of reflection events are much improved by SVD filtering than f-k filtering by eliminating the ground-roll with preserving the low-frequency reflections. This is well explained in the average amplitude spectra of the f-k and SVD filtered data. The reflectors including horizontal layer of the reservoir are much clearer on the stack section, with laminated events by SVD filtering and subsequent processing steps of spiking deconvolution and time-variant spectral whitening.

• Journal of Wetlands Research
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• v.13 no.1
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• pp.1-11
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• 2011

A chronic drought stress has been imposed during non-rainy season(from winter to spring) since 1990s. We faced the most significant water crisis in 2001, and the drought was characterized by sultry weather and severe drought on a national scale. It has been widely acknowledged that the drought related damage is 2-3 times serious than floods. In the list of the world's largest natural disaster compiled by NOAA, 4 of the top 5 disasters are droughts. And according to the analysis from the NDMC report, the drought has the highest annual average damage among all the disasters. There was a very serious impact on the economic such as rising consumer price during the 2001 spring drought in Korea. There has been flood prevention measures implemented at national-level but for mitigation of droughts, there are only plans aimed at emergency (short-term) restoration rather than the comprehensive preventive measures. In addition, there is a lack of a clear set of indicators to express drought situation objectively, and therefore it is important and urgent to begin a systematic study. In this study, a nonstationary downscaling model using RCM based climate change scenario was first applied to simulate precipitation, and the simulated precipitation data was used to derive Standardized Precipitation Index (SPI). The SPI under climate change was used to evaluate the spatio-temporal variability of drought through principal component analysis at three different time scales which are 2015, 2045 and 2075. It was found that spatio-temporal variability is likely to modulate with climate change.

• Journal of the Korean Wood Science and Technology
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• v.51 no.3
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• pp.157-172
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• 2023

Azadirachta excelsa, is a plant belonging to the same genus as Indian neem (Azadirachta indica), and its use as a pesticide is reported by few studies. Despite being a different species, it is expected to have the same biopesticide potential as A. indica. Therefore, this study aims to investigate the anti-termite activity of n-hexane and methanol extracts of A. excelsa seed kernel at various concentrations against Coptotermes curvignathus. The methanol extract demonstrated greater termicidal activity than n-hexane at doses test of 2%, 4%, and 8%. It also showed 100% termite mortality on the third day of administering the 8% dose. According to the gas chromatography with mass spectrometry data, the putative main components of the n-hexane extract were hexadecanoic acid, ethyl ester (18.99%), 9,12-octadecadienoic acid (Z,Z)- (16.31%), and 9-octadecenal (16.23%). In contrast, the principal constituents of methanol extract were patchouli alcohol (28.1%), delta-guaiene (15.15%), and alpha-guaiene (11.93%). Furthermore, limonoids profiling of A. excelsa methanol extract was determined using Ultrahigh-performance liquid chromatography coupled with quadrupole-Orbitrap high-resolution mass spectrometry. The number of limonoids identified tentatively was fifteen, such as 6-deacetylnimbin, nimbolidin C, nimbolide, 6-acetylnimbandiol, 6-deacetyl-nimbinene, salannol, 28-deoxonimbolide, gedunin, nimbandiol, epoxyazadiradione, azadirone, 2',3'-dihydrosalannin, marrangin, nimbocinol, and azadirachtin. They were the same as those reported in the seed and leaves of A. indica, but its largest component in A. excelsa was 6-deacetylnimbin. As a result, the presence of these compounds may be responsible for the anti-termite activity of A. excelsa seed kernel extract. Additionally, column chromatography of methanol extract yielded 6-deacetylnimbin, which was found to be antifeedant and termiticide against C. curvignathus.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6B
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• pp.599-606
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• 2010

Due to the short period of precipitation data in Korea, the uncertainty of drought analysis is inevitable from a point frequency analysis. So it is desired to introduce a regional drought frequency analysis. This study first extracted drought characteristics from 3-month and 12-month moving average rainfalls which represent short and long-term droughts, respectively. Then, the homogeneous regions were distinguished by performing a principal component analysis and cluster analysis. The Korean peninsula was classified into five regions based on drought characteristics. Finally, this study applied the bivariate frequency analysis using a kernel density function to quantify the regionalized drought characteristics. Based on the bivariate drought frequency curves, the drought severities of five regions were evaluated for durations of 2, 5, 10, and 20 months, and return periods of 5, 10, 20, 50, and 100 years. As a result, the largest severity of drought was occurred in the Lower Geum River basin, in the Youngsan River basin, and over in the southern coast of Korea.

• Journal of the Korean Geographical Society
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• v.30 no.2
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• pp.169-187
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• 1995

Contemporary US metropolitan areas have undergone divergent economic transformation, and as a result labor markets have become the focus of concern in their role as determinants of earnings attainment. Explanations of individual earnings attainmnent as a lobor market outcome have been established in two diafferent stances one who emphasizes personal or group attributes in the human capital perspective and the other who emphasizes economic structure in the labor market segmentation perspective. While remaining at the conceptual level and yet relatively unexplored, the importance of place in labormarket operation is a significant advancement as it appears in labor market areas and local labor markets considering that labor market areas represent the intersection of labor market structure and individual labor market experiences at specific geographic places. The substantive inquiry of this study was to explore labor market characteristics and their differentiation across large metropolitan areas, and assess their effects on the individual earnings attainment. Integating individual attributes and labor market characteristics as major factors of labor market operation, this study intended to contextualize individual earnings attainment with geographic labor market areas. Using 1990 US population census 5% "Public-Use Microdata Samples, " the largest 65 metropolitan areas were first selected and employed male workers who are aged between 25 and 50 for whites, blacks, asians, and hispanics. As an initial step earnings differentials between racial/ethnic groups and selected 65 metropolitan areas were examined using analysis of variance, and then earnings differentials were attributed to the individual attributes such as education, age, and immigration status, and four dimensions of metropolitan labor market differentiation devised by principal component analysis of industrial and occupational segments: Public versus Blue Collar Core(CS1), Finance-Core Utility versus Blue Collar Local Monopoly (CS2), Oligopoly versus Blue Collar Periphery(CS3), and Self Employed-White Collar Periphery versus Low-Skill Core(CS4). As a final analysis, individual earnings were related to each individual attribute and its interaction with metropolitan labor market characteristics to examine how the differentiated metropolitan labor market characteristics alter the role of individual attributes on earnings attainment. The findings indicated that individual attributes, education in particular exert significant effects on earnings attainment, but their effects were significantly altered by metropolitan labor market characterristics. Particularly important dimensions were: Oligopoly differentiated from Blue Colla Periphery metropolitan areas enhancing earnings returns to individual attributes for all groups but minority groups (black, asians, hispanics) rely more on this, and Finance-Core Utility differentiated from Blue Collar Local Monopoly metropolitan areas provide higher earnings returns to whites exclusively. These findings suggest that individuals with identical individual attributes involving racial/ethnic categories would have different earnings atteinments depending on the metropolitan labor market characteristics where they reside. Referring back to the major traditions of the human capital and the labor market segmentation in labor market research, the interaction between individual attributes and metropolitan labor market haracteristics on earnings attainment highlights the complimentary nature of the two on earnings determination in particular geographic places, Hence, labor market characteristics differentiatcd across metropolitan areas are an integral part of labor market operation which should be considered for the explanation of individual earnings attainment and racial/ethnic group earnings differentials. Gcographic places are the important contexts for labor market segmentation and individual labor market experiences. In conclusion, this study brings geographic labor markets to the forefront in the examination of individuals' earnings attainments. The empirical vaidation of the role of metropolitan labor market charecteristics on earnings attainment, while exploratory contributes towards a broader perspective of geographic labor market research that recognizes that individuals' labor market experiences are intertwined with geographic contexts of labor market operatin. operatin.