• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.309-310
• /
• 2023

Slag and ash generally have a higher powder degree than portland cement, so workability may deteriorate under the same unit quantity condition, and strength and durability decrease when the unit quantity is increased. At this time, if an aggregate having a low water absorption and an appropriate particle size is used to recover the loss of strength, it can contribute to reducing the unit quantity of the binder. Therefore, for the purpose of improving the workability and strength of non-sintered cement mortar using slag and ash, ferro nikel slag whose particle size was adjusted was used as an aggregate and its applicability was identified. In this experimental condition, it was confirmed that non-sintered cement mortar tends to improve workability and secure strength when ferro nikel slag having various particle size distributions is used as an aggregate. This can be analyzed as the effect of ferro nikel slag material properties including glassy properties and mixing conditions with a wide particle size distribution.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.216-216
• /
• 2022

The starch-branching enzymes (BEs) are responsible for synthesizing the amylopectin, which plays an important role in determining the structural and physical properties of starch granules. BE has two differently functioning isoforms (BEI and BEIIa/b) based on their difference in the chain-length pattern by the degree of polymerization (DP), which mainly contributes to the amylopectin chain length distribution in starch biosynthesis. In this study, we investigated functional haplotypes and evolutionary analyses of SBE1 in 374 rice accessions (320 Korean bred and 54 wild). The analyses were performed based on the classified subpopulations. Haplotype analysis generates a total of 8 haplotypes, of which only four haplotypes were functional carrying four functional SNPs in four different exons of SBE1 on chromosome 6. Nucleotide diversity analysis showed a highest pi-value in aromatic group (0.0029), while the lowest diversity value was in temperate japonica (0.0002), indicating the signal of this gene evolution origin. Different directional selections could be estimated by negative Tajima's D value of temperate japonica (-1.1285) and positive Tajima's D value of tropical japonica (0.9456), where the selective sweeps were undergone by both positive purifying and balancing selections. Phylogenetic analysis indicates a closer relationship of the wild with most of the cultivated subgroups indicating a common ancestor for SBE1 gene. FST-values indicate distant genetic relationships of temperate japonica from all other classified groups. PCA and population structure analysis show an admixed structure of wild and cultivated subpopulations in some proportions.

• Korea Trade Review
• /
• v.47 no.3
• /
• pp.211-232
• /
• 2022

Due to the impact of the public health event COVID-19 epidemic, the Chinese futures market showed "Black Swan". This has brought the unpredictable into the economic environment with many commodities falling by the daily limit, while gold performed well and closed in the sunshine(Yan-Li and Rui Qian-Wang, 2020). Volatility is integral part of financial market. As an emerging market and a special precious metal, it is important to forecast return of gold futures price. This study selected data of the SHFE gold futures returns and conducted an empirical analysis based on the generalised autoregressive conditional heteroskedasticity (GARCH)-type model. Comparing the statistics of AIC, SC and H-QC, ARMA (12,9) model was selected as the best model. But serial correlation in the squared returns suggests conditional heteroskedasticity. Next part we established the autoregressive moving average ARMA-GARCH-type model to analysis whether Volatility Clustering and the leverage effect exist in the Chinese gold futures market. we consider three different distributions of innovation to explain fat-tailed features of financial returns. Additionally, the error degree and prediction results of different models were evaluated in terms of mean squared error (MSE), mean absolute error (MAE), Theil inequality coefficient(TIC) and root mean-squared error (RMSE). The results show that the ARMA(12,9)-TGARCH(2,2) model under Student's t-distribution outperforms other models when predicting the Chinese gold futures return series.

• Journal of Environmental Science International
• /
• v.32 no.11
• /
• pp.789-800
• /
• 2023

A vascular flora survey was conducted in 2020 to identify flora and analyze changes in the numbers of vascular flora species over the past 10 years at Gongju-weir (GW) and Baekje-weir (BW) in the Geumgang River, Republic of Korea. A total of 241 taxa were found in GW and 279 taxa in BW, and 208 taxa (88% of total taxa) were common species. The distribution of invasive species in GW and BW were seven and eight taxa, respectively. Rare plants were not identified in any of the weirs. The Poaceae family dominated in terms of number of species, followed by Asteraceae, Legumes, Cyperaceae, and Polygonaceae. Additionally, Therophytes accounted for a high proportion of Raunkiaer life forms. The numbers of vascular plant species, total taxa, naturalized plants, and invasive species have been increasing over the last 10 years. However, long-term alterations in invasive species before and after the opening of the weirs increased much more significantly in the partially opened BW than in the fully opened GW. These results indicate that the degree of barrier opening does not affect the invasion and establishment of non-native species.

• International conference on construction engineering and project management
• /
• 2011.02a
• /
• pp.534-541
• /
• 2011

Risk evaluation approaches for bidding on international construction projects are typically partitioned into three stages: country selection, project classification, and bid-cost evaluation. However, previous studies are frequently under attack in that they have several crucial limitations: 1) a dearth of studies about country selection risk tailored for the overseas construction market at a corporate level; 2) no consideration of uncertainties for input variable per se; 3) less probabilistic approaches in estimating a range of cost variance; and 4) less inclusion of covariance impacts. This study thus suggests a three-staged risk evaluation model to resolve these inherent problems. In the first stage, a country portfolio model that maximizes the expected construction market growth rate and profit rate while decreasing market uncertainty is formulated using multi-objective genetic analysis. Following this, probabilistic approaches for screening bad projects are suggested through applying various data mining methods such as discriminant logistic regression, neural network, C5.0, and support vector machine. For the last stage, the cost overrun prediction model is simulated for determining a reasonable bid cost, while considering non-parametric distribution, effects of systematic risks, and the firm's specific capability accrued in a given country. Through the three consecutive models, this study verifies that international construction risk can be allocated, reduced, and projected to some degree, thereby contributing to sustaining stable profits and revenues in both the short-term and the long-term perspective.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.18 no.4
• /
• pp.1020-1041
• /
• 2024

With the development of covert communication technologies, the number of covert communication technologies using blockchain as a carrier is increasing. However, using the transaction amount of digital currency as a carrier for covert communication has problems such as low embedding rate, large consumption of transaction amount, and easy detection. In this paper, firstly, by experimentally analyzing the distribution of bitcoin transaction amounts, we determine the most suitable range of amounts for matrix decomposition. Secondly, we design a novel matrix decomposition method that can successfully decompose a large amount matrix into two small amount matrices and utilize the elements in the small amount matrices for covert communication. Finally, we analyze the feasibility of the novel matrix decomposition method in this scheme in detail from four aspects, and verify it by experimental comparison, which proves that our scheme not only improves the embedding rate and reduces the consumption of transaction amount, but also has a certain degree of resistance to detection.

• Journal of Korea Artificial Intelligence Association
• /
• v.2 no.1
• /
• pp.25-30
• /
• 2024

Kodály hand signs are symbols that intuitively represent pitch and note names based on the shape and height of the hand. They are an excellent tool that can be easily expressed using the human body, making them highly engaging for children who are new to music. Traditional hand signs help beginners easily understand pitch and significantly aid in music learning and performance. However, Kodály hand signs have distinctive features, such as the ability to indicate key changes or chords using both hands and to clearly represent accidentals. These features enable the effective use of Kodály hand signs. In this paper, we aim to investigate the changes in recognition rates according to the complexity of scales by creating a device for learning Kodály hand signs, teaching simple Do-Re-Mi scales, and then gradually increasing the complexity of the scales and teaching complex scales and children's songs (such as "May Had A Little Lamb"). The learning device utilizes accelerometer and bending sensors. The accelerometer detects the tilt of the hand, while the bending sensor detects the degree of bending in the fingers. The utilized accelerometer is a 6-axis accelerometer that can also measure angular velocity, ensuring accurate data collection. The learning and performance evaluation of the Kodály learning device were conducted using Python.

• Journal of Korean Association for Spatial Structures
• /
• v.24 no.3
• /
• pp.61-68
• /
• 2024

High-rise buildings are equipped with TMD (Tuned Mass Damper), a vibration control device that ensure the stability and usability of the building. In this study, the seismic response control performance was evaluated by selecting the design variables of the TMD based on the installation location of the twisted irregular building. To this end, we selected analysis models of 60, 80, and 100 floors with a twist angle of 1 degree per floor, and performed time history analysis by applying historical seismic loads and resonant harmonic loads. The total mass ratio of TMDs was set to 1.0%, and the distributed installation locations of TMDs were selected through mode analysis. The analysis results showed that the top-floor displacement responses of all analysis models increased, but the maximum story drift ratio decreased. In order to secure the seismic response control performance by distributed installation of TMDs in twisted irregular buildings, it is judged that the mass ratio distribution of TMDs will act as a key variable.

• Asia pacific journal of information systems
• /
• v.17 no.4
• /
• pp.187-206
• /
• 2007

The development of computer and information technology has been combined with the information superhighway internet infrastructure, so information widely spreads not only in special fields but also in the daily lives of people. Information ubiquity influences the traditional way of transaction, and leads a new E-commerce which distinguishes from the existing E-commerce. Not only goods as physical but also service as non-physical come into E-commerce. As the scale of E-Commerce is being enlarged as well. It keeps people from finding information they want. Recommender systems are now becoming the main tools for E-Commerce to mitigate the information overload. Recommender systems can be defined as systems for suggesting some Items(goods or service) considering customers' interests or tastes. They are being used by E-commerce web sites to suggest products to their customers who want to find something for them and to provide them with information to help them decide which to purchase. There are several approaches of recommending goods to customer in recommender system but in this study, the main subject is focused on collaborative filtering technique. This study presents a possibility of pre-evaluation for the prediction performance of customer's preference in collaborative filtering before the process of customer's preference prediction. Pre-evaluation for the prediction performance of each customer having low performance is classified by using the statistical features of ratings rated by each customer is conducted before the prediction process. In this study, MovieLens 100K dataset is used to analyze the accuracy of classification. The classification criteria are set by using the training sets divided 80% from the 100K dataset. In the process of classification, the customers are divided into two groups, classified group and non classified group. To compare the prediction performance of classified group and non classified group, the prediction process runs the 20% test set through the Neighborhood Based Collaborative Filtering Algorithm and Correspondence Mean Algorithm. The prediction errors from those prediction algorithm are allocated to each customer and compared with each user's error. Research hypothesis : Two research hypotheses are formulated in this study to test the accuracy of the classification criterion as follows. Hypothesis 1: The estimation accuracy of groups classified according to the standard deviation of each user's ratings has significant difference. To test the Hypothesis 1, the standard deviation is calculated for each user in training set which is divided 80% from MovieLens 100K dataset. Four groups are classified according to the quartile of the each user's standard deviations. It is compared to test the estimation errors of each group which results from test set are significantly different. Hypothesis 2: The estimation accuracy of groups that are classified according to the distribution of each user's ratings have significant differences. To test the Hypothesis 2, the distributions of each user's ratings are compared with the distribution of ratings of all customers in training set which is divided 80% from MovieLens 100K dataset. It assumes that the customers whose ratings' distribution are different from that of all customers would have low performance, so six types of different distributions are set to be compared. The test groups are classified into fit group or non-fit group according to the each type of different distribution assumed. The degrees in accordance with each type of distribution and each customer's distributions are tested by the test of ${\chi}^2$ goodness-of-fit and classified two groups for testing the difference of the mean of errors. Also, the degree of goodness-of-fit with the distribution of each user's ratings and the average distribution of the ratings in the training set are closely related to the prediction errors from those prediction algorithms. Through this study, the customers who have lower performance of prediction than the rest in the system are classified by those two criteria, which are set by statistical features of customers ratings in the training set, before the prediction process.

• Journal of Environmental Impact Assessment
• /
• v.25 no.2
• /
• pp.103-123
• /
• 2016

This study is a comparison of the flora and case studies distributed in Gulup-do Ongjingun, Incheon. The numbers of vascular plants were summarized as 282 taxa including 81 families, 201 genera, 252 species, 3 subspecies, 22 varieties and 5 forms. The Raunkiaer life forms are analyzed in hemicryptophytes were 66 taxa (23.4%) in dormancy form, non-clonal growth ($R_5$) were 160 taxa (56.7%) in propagation form of radicoid form, having no special modification for dissemination ($D_4$) were 197 taxa (48.6%) in propagation form of disseminule form, erect form (e) were 117 taxa (41.5%) in growth form. The halophytes were 23 taxa including Salsola collina, Asparagus oligoclonos and so on. The rare plants were 7 taxa including Pyrrosia hastata (VU), Senecio nemorensis (VU) and so on. The Korean endemic plants were 5 taxa including Hepatica insularis, Lespedeza maritima and so on. In the specific plants by floristic region were 38 taxa, a degree I were 23 taxa (Dictamnus dasycarpus, Vitex rotundifolia and so on), 6 taxa of a degree II (Morus cathayana, Euphorbia esula and so on), 8 taxa of a degree III (Pyrrosia hastata, Rhodotypos scandens and so on), Senecio nemorensis of a degree V and degree IV were not found. The naturalized plants were 17 taxa including Robinia pseudoacacia, Bromus tectorumand so on. Of those Ambrosia artemisiifolia is a invasive alien plants. Naturalization rate (NR) was 6.0% of all 282 taxa of vascular plants and urbanization index (UI) was 5.3% of all 321 taxa of naturalized plants. Gulup-do and adjacent Baega-do were locally investigated field work and it summarizes the results of a total of 41 islands literature in Ongjin-gun and Ganghwa-gun, Incheon including uninhabited islands, Baengnyeong-do, Daecheong-do and so on. The average number of species were each analyzed in about 89 taxa, rare plants are about 2 taxa, endemic plants are about 1 taxa, naturalized plants are about 4 taxa. This study was the comparison of the flora and literature distribution case that the Gulup-do maintain the naturalness and continuously conducted to explore the future conservation measures the adjacent islands.