• Journal of Plant Biotechnology
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• 제49권1호
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• pp.74-81
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• 2022

Brassica napus, an oil crop that produces rapeseed oil, is an allotetraploid (AACC, 2n = 38) produced by natural hybridization between B. rapa and B. oleracea. In this study, microspore was cultured using the F₁ developed from a cross between 'EMS26' line with high oleic acid content and 'J8634-B-30' lines. The flower bud size showing the nuclear development at the late uninucleate and binucleate stage with high embryogenesis rate was 2.6 ~ 3.5 mm. Microspores were cultured using only this size and after then most microspore embryo developed into secondary embryos and then regeneration plants obtained from the developed multilobe. The analysis of the ploidy of the plants revealed that 66.7% and 27.8% of the total lines were tetraploids and octoploids, respectively. The sizes of stomatal cells in tetraploids, octoploids, and diploids were 25.5, 35.6, and 19.9 ㎛, respectively, indicating that ploidy level was positively correlated with cell size. Furthermore, 62 tetraploid doubled haploid (DH) lines were selected. The average oleic acid (C18:1) and linolenic acid (C18:3) concentrations of DH were 72.3% and 6.2%, respectively. Oleic acid and linolenic acid concentrations exceeded the two parental values in 5 and 14 DH lines, respectively, suggesting that these two fatty acids had transgressive segregation. Therefore, the DH population can be utilized for the biosynthesis of unsaturated fatty acids in rapeseed and related genes. It can also be used as a breeding material for varieties with high oleic acid concentrations.

• KOREAN JOURNAL OF CROP SCIENCE
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• 제30권3호
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• pp.252-258
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• 1985

An experiment was conducted at the Yeongnam Crop Experiment Station to obtain basic informations about cultural techniques for high yielding by manipulating plant spacing using two rice cultivars, Samgangbyeo (Indica/Japonica type) and Nakdongbyeo (Japonica type), and four plant spacings, 10${\times}$10cm, 20${\times}$20cm 30${\times}$30cm and 40${\times}$40cm, with 4 kinds of seedling number per hill, 1,3,5 and 7, respectively. High photosynthetic efficiency (Eu) exhibited at the Samgangbyeo compared to Nakdongbyeo regardless of plant spacings and seedling numbers. For Samgangbyeo, Eu value was the highest at the 20${\times}$20cm plant spacing and five seedlings and seven seedlings per hill showed high Eu values at 10${\times}$10cm plant spacing and 20${\times}$20cm plant spacing, respectively, while other plant spacings were not significantly differed among seedling numbers. For Nakdongbyeo, however, one seedling plot obtained high Eu value at the 10${\times}$10cm plant spacing while this Eu value increased as the seedling number per hill increased in other plant spacings. There was a high positive correlation between rice grain yield and total competition index for both cultivars while kind of relationships differed in these two cultivars; linear relationship for Samgangbyeo and exponential relationship for Nakdongbyeo, respectively. Competition index between rice hill was more significant than within rice hill for Samgangbyeo while both competition indexs were important for Nakdongbyeo to increase rice yield.

• Journal of the Korea Organic Resources Recycling Association
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• 제31권1호
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• pp.35-45
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• 2023

In this study, the sludge formation in the wastewater drain from the advanced packaging process mechanisms are revealed as well as the key factors, materials, and sludge prevention methods using surfactant. Compared with that of conventional packaging process, advanced packaging process employ similar process to the semiconductor fabrication process, and thus many processes may generate wastewater. In specific, a large amount of wastewater may generate during the carrier wafer bonding, photo, development, and carrier wafer debonding processes. In order to identify the key factors for the formation of sludge during the advanced packaging process, six types of chemicals including bonding glue, HMDS, photoresist (PR), PR developer, debonding cleaner, and water are utilized and mixing evaluation is assessed. As a result, it is confirmed that the black solid sludge is formed, which is originated by the sludge seed formation by hydrolysis/dehydration reaction of HMDS and sludge growth via hydrophobic-hydrophobic binding with sludge seed and PR. For the sludge prevention investigation, three surfactants of CTAB, PEG, and shampoo are mixed with the key materials of sludge, and it is confirmed that the sludge formations are successfully suppressed. The underlying mechanism behind the sludge formation is that the carbon tails of the surfactant bind to PR with hydrophobic-hydrophobic interaction and inhibit the reaction with HMDS-based slurry seeds to prevent the sludge formation. In this regard, it is expected that various problems like clogging in drains and pipes during the advanced packaging process may effectively solve by the injection of surfactants into the drains.

• KOREAN JOURNAL OF CROP SCIENCE
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• 제68권3호
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• pp.134-146
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• 2023

Phytophthora root rot (PRR) is a major soybean disease caused by an oomycete, Phytophthora sojae. PRR can be severe in poorly drained fields or wet soils. The disease management primarily relies on resistance genes called Rps (resistance to P. sojae). This study aimed to identify resistance loci associated with resistance to P. sojae isolate 40468 in Daepung × CheonAl recombinant inbred line (RIL) population. CheonAl is resistant to the isolate, while Daepung is generally susceptible. We genotyped the parents and RIL population via high-throughput single nucleotide polymorphism genotyping and constructed a set of genetic maps. The presence or absence of resistance to P. sojae was evaluated via hypocotyl inoculation technique, and phenotypic distribution fit to a ratio of 1:1 (R:S) (χ² = 0.57, p = 0.75), indicating single gene mediated inheritance. Single-marker association and the linkage analysis identified a highly significant genomic region of 55.9~56.4 megabase pairs on chromosome 18 that explained ~98% of phenotypic variance. Many previous studies have reported several Rps genes in this region, and also it contains nine genes that are annotated to code leucine-rich repeat or serine/threonine kinase within the approximate 500 kilobase pairs interval based on the reference genome database. CheonAl is the first domestic soybean genotype characterized for resistance against P. sojae isolate 40468. Therefore, CheonAl could be a valuable genetic source for breeding resistance to P. sojae.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• 제18권5호
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• pp.185-196
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• 2023

This paper investigates the effects of entrepreneurs' cognitive biases on business opportunity evaluation, given their strong entrepreneurial spirit, which is characterized by innovation, proactivity, and risk-taking. When making decisions related to business activities, entrepreneurs typically make rational judgments based on their knowledge, experience, and the advice of external experts. However, in situations of extreme stress or when quick decisions are required, they often rely on heuristics based on their cognitive biases. In particular, we often see cases where entrepreneurs fail because they make decisions based on heuristics in the process of evaluating and selecting new business opportunities that are planned to guarantee the growth and sustainability of their companies. This study was conducted in response to the need for research to clarify the effects of entrepreneurs' cognitive biases on new business opportunity evaluation, given that the cognitive biases of entrepreneurs, which are formed by repeated successful experiences, can sometimes lead to business failure. Although there have been many studies on the effects of cognitive biases on entrepreneurship and opportunity evaluation among university students and general people who aspire to start a business, there have been few studies that have clarified the relationship between cognitive biases and social networks among entrepreneurs. In contrast to previous studies, this study conducted empirical surveys of entrepreneurs only, and also conducted research on the relationship with social networks. For the study, a survey was conducted using a parallel survey method using online mobile surveys and self-report questionnaires from 150 entrepreneurs of small and medium-sized enterprises. The results of the study showed that 'overconfidence' and 'illusion of control', among the independent variables of entrepreneurs' cognitive biases, had a statistically significant positive(+) effect on business opportunity evaluation. In addition, it was confirmed that the moderating variable, social network, moderates the effect of overconfidence on business opportunity evaluation. This study showed that entrepreneurs' cognitive biases play a role in the process of evaluating and selecting new business opportunities, and that social networks play a role in moderating the structural relationship between entrepreneurs' cognitive biases and business opportunity evaluation. This study is expected to be of great help not only to entrepreneurs, but also to entrepreneur education and policy making, by showing how entrepreneurs can use cognitive biases in a positive way and the influence of social networks.

• Land and Housing Review
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• 제15권1호
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• pp.1-22
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• 2024

This research explores the household and housing characteristics of young renters aged between 19 and 34 living independently in rental housing of non-Seoul Metropolitan Area (non-SMA) and to determine the factors of their housing affordability and residential environment qualities in two districts of non-SMA - metropolises and non-metropolises. Using the 2020 Korean Housing Survey (KHS), this study identified 1,191 unmarried young renters, and most were single adults in mid-twenties who were salaried workers with a bachelor's degree or higher. Also, many lived in single-room occupancy of non-APT housing for less than 2 years and rarely relied on social services. The findings showed that the distinction of local housing market between metropolises and non-metropolises forced the former to spend more housing expense (tenancy deposit and rental fees) than the latter. With regard to housing affordability indices (Schwabe index, housing expense ratio and rent to income ratio), most were housing cost-burdened and nearly one quarter were severely rent-burdened. The regression analysis indicated that housing affordability in both districts was positively affected by income increase and social services, and housing satisfaction in non-metropolises was added to its determinants. Further, residential environment qualities were largely divided into two groups of livelihood and urban infrastructure, and the two factors influenced residential assessment in both districts. Since young renters interdependently living had suffered with housing affordability, both income growth and housing assistance are critically required to enable them not just to reduce the burden but to ensure livability.

• Journal of Korea Water Resources Association
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• 제57권7호
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• pp.437-449
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• 2024

Rainfall-runoff prediction studies using deep learning while considering catchment attributes have been gaining attention. In this study, we selected two models: the Transformer model, which is suitable for large-scale data training through the self-attention mechanism, and the LSTM-based multi-state-vector sequence-to-sequence (LSTM-MSV-S2S) model with an encoder-decoder structure. These models were constructed to incorporate catchment attributes and predict the inflow of 10 multi-purpose dam watersheds in South Korea. The experimental design consisted of three training methods: Single-basin Training (ST), Pretraining (PT), and Pretraining-Finetuning (PT-FT). The input data for the models included 10 selected watershed attributes along with meteorological data. The inflow prediction performance was compared based on the training methods. The results showed that the Transformer model outperformed the LSTM-MSV-S2S model when using the PT and PT-FT methods, with the PT-FT method yielding the highest performance. The LSTM-MSV-S2S model showed better performance than the Transformer when using the ST method; however, it showed lower performance when using the PT and PT-FT methods. Additionally, the embedding layer activation vectors and raw catchment attributes were used to cluster watersheds and analyze whether the models learned the similarities between them. The Transformer model demonstrated improved performance among watersheds with similar activation vectors, proving that utilizing information from other pre-trained watersheds enhances the prediction performance. This study compared the suitable models and training methods for each multi-purpose dam and highlighted the necessity of constructing deep learning models using PT and PT-FT methods for domestic watersheds. Furthermore, the results confirmed that the Transformer model outperforms the LSTM-MSV-S2S model when applying PT and PT-FT methods.

• Tunnel and Underground Space
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• 제34권4호
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• pp.374-392
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• 2024

In order to successfully select a site for deep geological disposal of high-level radioactive waste, it is important to perform the stepwise approach along with the systematic selection and survey of evaluation parameters of geological environmental characteristics suitable for the domestic geological environment. In this study, we evaluated the characteristics of hydraulic conductivity, which is considered the most important evaluation parameter in the field of hydrogeology, targeting a deep-depth rock aquifer where actual disposal facilities are expected to be located. In particular, for the first time in Korea, we obtained in-situ pressure-flow data by directly conducting hydraulic tests in boreholes at depths ranging from 500 m to 750 m in various rock types distributed in Korea (granite/volcanic rock/gneiss/mudstone). And we derived hydraulic conductivity values by rock types and depth using verified analytical methods. For this purpose, precision hydraulic testing equipment developed in-house through this study was used, and detailed investigation procedures based on standard test methods were applied to field tests. As a result of the analysis, the average hydraulic conductivity value was found to be in the range of 10^-9 m/s in all granite/volcanic rock/gneiss areas. In the mudstone area, an average hydraulic conductivity value of 10^-11 m/s was derived, which was about 100 times (2 orders of magnitude) lower than that of the fractured rock aquifers. Moreover, permeability tended to slightly decrease with depth in fractured rock aquifers (granite and volcanic rock areas) containing many rock fractures. The gneiss area tended to have large local differences in permeability according to the composition of the stratum and the development of fracture zones rather than depth. In mudstone areas with weak fracture development, there was no significant variation in rock permeability according to depth. The hydraulic conductivity results by various rock types and depth presented in this study are expected to be utilized in building a foundational database for the site selection, design, and construction of disposal facilities in Korea.

• Journal of the Economic Geographical Society of Korea
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• 제27권3호
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• pp.155-173
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• 2024

Using Regional Employment Survey, this article analyzes the widening employment gap between Capital and Non-Capital regions since the 2008 global financial crisis through describing the spatial distribution of employment by industry and occupation, calculating the regional downward employment rate of university graduates, and estimating the regional distribution of employment growth in terms of wage distribution, and then statistically analyzes the effect of the declining manufacturing employment in the Non-Capital region since the mid-2010s on total employment change. The results from these analyses are as follows. First, since the mid-2000s, the share of producer services and white-collar jobs has increased in the Capital region. Second, the Non-Capital region has a higher share of non-regular workers relative to wage workers than the Capital region. Third, while the downward employment rate has increased in the Non-Capital region since the mid-2010s, it has risen very modestly or stagnated in the Capital region. Fourth, in terms of wage distribution, the pattern of employment growth since the mid-2010s has been U-shaped, a typical polarized pattern of simultaneous growth in low- and high-wage jobs and decline in middle-wage jobs in the Non-Capital region, while in the Capital region it has been L-shaped with the sides reversed, driven by growth in high-wage jobs. Fifth, this employment polarization in the Non-Capital region since the mid-2010s is associated with employment changes in manufacturing, which accounts for a large share of middle wage jobs. Finally, according to the analysis of the effect of regional manufacturing employment changes on total employment changes since the mid-2010s, declines in manufacturing employment reduce the region's regular employment rate and have a larger negative employment effect in the Non-Capital region. Based on these findings, some policy issues are discussed including the branch plant economy regime based on spatial separation of conception and execution, the mix of geographic and skill mobility, the need to improve employability and jobs through human capital accumulation, and short- and long-term responses to employment fluctuations.

• Korean Journal of Agricultural Science
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• 제9권1호
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• pp.396-450
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• 1982

To obtain basic information on the Korean local corn lines a total of 57 lines were selected from 1,000 Korean local collection at Chungnam National University, classified by principal component analysis, and genetic nature was investigated. The results are summarized as follows. 1. There were a great variation in mean values of plant characters of the lines. The mean values of plant characters except for density of kernels varied with types of crossing. All characters except. for tasselling dates were reduced in magnitude when selfed, while those characters were increased when topcrossed. 2. The correlation coefficients among characters studied ranged front 0.99 to -0.59. The correlation coefficients among characters were not greatly changed depending upon types of crosses. 3. In order to classify the lines more effectively, selected 12 plant characters were used to classify 57 local lines by principal component analysis. The first four component could explain 86.4%, 83.4% and 81.1% of the total variations in sibbed lines, selfed lines and topcrossed lines, respectively. 4. Contribution of characters to principal component was high at upper principal components and low at lower principal components. 5. Biological meaning of the principal component and plant types corresponding to the each principal component were explained clearly by the correlation coefficient between principal components and characters. The first principal component appeared to correspond to the size of plant and ear. The second principal component appeared to correspond to the degree of differentiation in organs and the duration of vegetative growing period. But biological meaning of the third and fourth principal components was not clear. 6. The lines were classified into 4 lineal groups by the taxonomic distance. Group I included 52 lines which was 91.2% of total lines, group II 3 lines, group III 1 lines and group IV I lines, respectively. Four groups could be characterized as follows : Group I : early maturity, short-culmed, medium height plant, small ears, medium kernels and medium yielding. Group II : late maturity, medium height plant, small ears, small kernels, prolific ears and higher yielding. Group III : medium maturity, tall-culmed, small ears, small kernels and low yielding. Group IV : medium maturity, tall-calmed, large ears, one ear plant and me yielding. 7. The inbreeding depression varied with plant characters and lines. The characters such as yield, kernel weight per ear, ear weight and plant height showed great degree of inbreeding depression. Group I showed high inbreeding depression in such characters as 100 kernel weight, leaf number, plant height and days to tasselling, while group II showed high inbreeding depression in other plant characters. 8. Heterosis of plant characters varied also with lines. The ear weight, kernel weight per ear, yield, 100 kernel weight, and plant height were some of the plant characters showing high heterosis. Group II showed high values of heterosis in such characters as ear length, ear diameter, ear weight, kernel weight per ear, 100 kernel weight, and leaf length, while group I was high in heterosis in other plant characters. 9. The degree of homozgosity was highest in ear weight (79.1%) and lowest in ear number per plant (-21%). Group II showed higher degree of homozygosity than group I. 10. Correlation coefficients between characters of ribbed and topcrossed lines were positive for all characters. Highly significant. correlation coefficients between ribbed and topcrossed lines were obtained especially for characters such as ear number per plant, plant height, leaf length and yield per plot.