• Smart Structures and Systems
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• v.6 no.5_6
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• pp.481-504
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• 2010

Wireless smart sensor networks (WSSNs) have been proposed by a number of researchers to evaluate the current condition of civil infrastructure, offering improved understanding of dynamic response through dense instrumentation. As focus moves from laboratory testing to full-scale implementation, the need for multi-hop communication to address issues associated with the large size of civil infrastructure and their limited radio power has become apparent. Multi-hop communication protocols allow sensors to cooperate to reliably deliver data between nodes outside of direct communication range. However, application specific requirements, such as high sampling rates, vast amounts of data to be collected, precise internodal synchronization, and reliable communication, are quite challenging to achieve with generic multi-hop communication protocols. This paper proposes two complementary reliable multi-hop communication solutions for monitoring of civil infrastructure. In the first approach, termed herein General Purpose Multi-hop (GPMH), the wide variety of communication patterns involved in structural health monitoring, particularly in decentralized implementations, are acknowledged to develop a flexible and adaptable any-to-any communication protocol. In the second approach, termed herein Single-Sink Multi-hop (SSMH), an efficient many-to-one protocol utilizing all available RF channels is designed to minimize the time required to collect the large amounts of data generated by dense arrays of sensor nodes. Both protocols adopt the Ad-hoc On-demand Distance Vector (AODV) routing protocol, which provides any-to-any routing and multi-cast capability, and supports a broad range of communication patterns. The proposed implementations refine the routing metric by considering the stability of links, exclude functionality unnecessary in mostly-static WSSNs, and integrate a reliable communication layer with the AODV protocol. These customizations have resulted in robust realizations of multi-hop reliable communication that meet the demands of structural health monitoring.

• Journal of Life Science
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• v.32 no.12
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• pp.1005-1012
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• 2022

This study was conducted to investigate the taxonomic composition and diversity of fecal microbiota between birth and weaning stages of Halla horses using 16S rRNA gene amplicon sequencing analysis. Proteobacteria (35.7%) and Firmicutes (45.6%) were identified as the most common phylum in birth and weaning, respectively. Escherichia (19.7%) and Clostridium (14.0%) were observed as the most dominant genus in birth, and Fibrobacter (6.6%) was the highest in weaning. The results of α-diversity showed that the richness and evenness in microbial communities were statistically significant (p<0.001) in birth and weaning. The results of β-diversity indicated that the birth and weaning stages were clearly divided into two groups at the genus and species levels. Permutational multivariate analysis of variance (PERMANOVA) showed that the microbiota composition differences between birth and weaning were statistically significant (q<0.001). A linear discriminant analysis effect (LEfSe) was performed to select taxonomic makers between the birth and weaning stages. On the genus level, Escherichia, Bacteroides, Clostridium, and Methylobacterium were relatively abundant at birth, whereas Fibrobacter was more abundant at weaning. We expect that this research can be utilized as basic data in the identification of microbial communities involved in disease prevention and nutrient absorption in Halla horses.

• Journal of Life Science
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• v.33 no.4
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• pp.325-333
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• 2023

This study compared and analyzed the microbial composition and physicochemical characteristics of kimchi (gimjang kimchi) and mukeunji (aged kimchi). Commercial kimchi and mukeunji products were purchased through an online market. After an analysis of physicochemical characteristics, the pH of the mukeunji samples was found to be lower and the acidity higher than in the kimchi samples. There was no significant difference in salinity between kimchi and mukeunji, but the sugar content was higher in the kimchi samples. The phylogenetic diversity index, which incorporates phylogenetic difference between species, was significantly higher in mukeunji than in the kimchi. The most dominant order in both groups was Lactobacillales, but several lactic acid bacteria, such as the Pediococcus and Lactobacillus species, which may be more acid tolerant or more competitive, are relatively predominant in mukeunji. Beta set-significance analysis based on two different distance metric results revealed that microbial distributions of population were different at the statistical confidence level (p<0.001). We investigated the effect of respective species on total microbial community using the LEfSe (linear discriminant analysis effect size) mechanism. According to the results of LEfSe testing, a relatively higher abundance of Weissella kandleri in kimchi and a higher abundance of Pediococcus inopinatus in mukeunji have the greatest influence on the differences in microbial structure between the two groups.

• Korean Journal of Environmental Biology
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• v.28 no.4
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• pp.179-187
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• 2010

The Theory of Island Biogeography describes that the number of species on an island affected by island area and distance from the mainland. This study was performed to compare and analyze the community structure of the macro-invertebrates in three isolated islands, around Korean waters in terms of the Theory of Island Biogeography. Macrobenthic animals were collected using a modified underwater quadrat in August 2009. A total of 104 macrobenthic species were sampled with a mean density of 399 individuals $m^{-2}$ and biomass of 1,506.70 g $m^{-2}$. Based on the abundance and biomass data, there were 10 dominant species accounting for approximately 67.17% of total individuals. The highest densities were found in the amphipoda Amphipoda spp., the bivalvia Modiolus agripetus and Mytilus coruscus, the Sipunculida Phascolosoma scolops and the polychaeta Syllidae unid.. On the contrary, the top ten species made up 95.66% of the total biomass while the three most abundant, the bivalves M. coruscus, Streostria circumpicta and M. agripetus. The conventional multi-variate statistics (cluster analysis and non-metric multi-dimensional scaling) applied to assess spatial variation in macrobenthic assemblages. Cluster analysis and nMDS ordination analysis based on the Bray-Curtis similarity identified 2 station groups. The group 1 was consisted with Gageodo (except for lower station at Transect 2) and Dokdo station and was numerically dominated by the polychaetes Eunice antennata and Syllidae unid., the cirripedia Megabalanus rosa and the bivalvia M. coruscus. However, group 2 was associated with Sohwado station and was characterized by high abundance of the anomura Petrolisthes japonicus, the gastropoda Lirularia pygmaea and the brachiopoda Coptothyris grayi. In conclusion, these results suggested that the species diversity and community structure of macrobenthos in three isolated island seemed slightly related to island area and distance from the mainland.

• Journal of the Korean Geographical Society
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• v.29 no.3
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• pp.297-317
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• 1994

This study demonstrates the changes in the spatial organization of Korea by the construction of Seoul-Pusan railroad. This Seoul-Pusan line, which is the most important one in Korea was constructed in 1905. The original plan of the line was selected to cross the main traditional roads to control the entire Korean peninsular and to mobilize the Korean commercial potentials. It was the line to exploit the staples and to expand the Japanese market in Korea. In accordance with the contracts between Japan and Korean government, Korean government had to supply the lands for railroad, office, and service facilities. That was one of the important reasons that Korean government had been broken down. The main findings of this study are as follows: 1. The Seoul-Pusan railroad line was constructed Japanese colonial policy which emphasized three main purposes; the first was to reorganize the economic space and to collapse the traditional Korean markets for Japanese ruling, and the second was to find out the military supply routes, and the third was to search for the transcontinental line for China and Siberia. As the results, the old Korean pedestrian routes, which were the Eastern, the mid, the westren, and the Samnam route lost their functions. 2. Japanese requested for Korean government usually ten times of wider space for the site of stations than the needed one. The land was expropriated, and constructed the new centers aparted from the original Korean towns. In this process Japanese got the most developmental and windfall profits. The newly constructed centers were for Japanese immigration and the town service facilities which would be used to control the Korean financial market. At last, they easily converted the Korean spatial economy into Japanese colonial one, which made to reinforce the sphere of Seoul-Pusan line. 3. Japanese planned the stations as the central points in Korea. So the railroad stations were located apart from the centers of towns, to avoid the Korean resistances, and to maximize their profits. The mean distance from staiton to 'the town center is about 1km while the Japanese case is 0.6km. 4. The pattern of present Korean railroads is not the 'X type'. Because the Honam line is not the trunk one. So, we could call the Korean railroad pattern as the 'Ip(Chinese character 入) type' . The operational effects of Seoul-Pusan line brought out the concentration of the national economy to this line as Japanese planned. And the polorization had occurred between this line and the other parts of Korea. For twenty years (1910-1930), the transported freights were increased about 5 times. In 1930, the total freight of Seoul-Pusan line became 2, 010, 444 metric tons. If we examine this process, the underconstructing Seoul-Pusan express electric railroad should avoid adjacent this line to reduce the regional and ecological imbalance. 5. The forms of centers on the Seoul-Pusan line were classified into six types in relation to station, town center, and built-up area; the compact (integrated) type, the elongated one, the splited (independent) one, the absorbed one, the consolidated one, and the declined one. All types of these towns might be developed in accordance with the centrality, railroad function, and the other transportational functions. 6. The Seoul-Pusan line plays the most important role among Korean railroads but the ratio of passenger and freight become lower because the effiects of other inaugurated railoads the different transportation modes such as trucks and cars would be got more merits in competition. 7. The results of cluster analyses on the cities of railroad stations showed the rudimentary urban systems in 1910 and 1930. In 1930, the cities were classified into three groups; the group of small cites, the intermediate (developing) city-group, and the special city-group. In 1930s the spatial organization and urban system of Korea were similar to the present ones. We call appreciate that these were the effects of the Seoul-Pusan line.

• Asia pacific journal of information systems
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• v.20 no.1
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• pp.81-99
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• 2010

Lately, in consumers' markets the number of new items is rapidly increasing at an overwhelming rate while consumers have limited access to information about those new products in making a sensible, well-informed purchase. Therefore, item providers and customers need a system which recommends right items to right customers. Also, whenever new items are released, for instance, the recommender system specializing in new items can help item providers locate and identify potential customers. Currently, new items are being added to an existing system without being specially noted to consumers, making it difficult for consumers to identify and evaluate new products introduced in the markets. Most of previous approaches for recommender systems have to rely on the usage history of customers. For new items, this content-based (CB) approach is simply not available for the system to recommend those new items to potential consumers. Although collaborative filtering (CF) approach is not directly applicable to solve the new item problem, it would be a good idea to use the basic principle of CF which identifies similar customers, i,e. neighbors, and recommend items to those customers who have liked the similar items in the past. This research aims to suggest a hybrid recommendation procedure based on the preference boundary of target customer. We suggest the hybrid recommendation procedure using the preference boundary in the feature space for recommending new items only. The basic principle is that if a new item belongs within the preference boundary of a target customer, then it is evaluated to be preferred by the customer. Customers' preferences and characteristics of items including new items are represented in a feature space, and the scope or boundary of the target customer's preference is extended to those of neighbors'. The new item recommendation procedure consists of three steps. The first step is analyzing the profile of items, which are represented as k-dimensional feature values. The second step is to determine the representative point of the target customer's preference boundary, the centroid, based on a personal information set. To determine the centroid of preference boundary of a target customer, three algorithms are developed in this research: one is using the centroid of a target customer only (TC), the other is using centroid of a (dummy) big target customer that is composed of a target customer and his/her neighbors (BC), and another is using centroids of a target customer and his/her neighbors (NC). The third step is to determine the range of the preference boundary, the radius. The suggested algorithm Is using the average distance (AD) between the centroid and all purchased items. We test whether the CF-based approach to determine the centroid of the preference boundary improves the recommendation quality or not. For this purpose, we develop two hybrid algorithms, BC and NC, which use neighbors when deciding centroid of the preference boundary. To test the validity of hybrid algorithms, BC and NC, we developed CB-algorithm, TC, which uses target customers only. We measured effectiveness scores of suggested algorithms and compared them through a series of experiments with a set of real mobile image transaction data. We spilt the period between 1st June 2004 and 31st July and the period between 1st August and 31st August 2004 as a training set and a test set, respectively. The training set Is used to make the preference boundary, and the test set is used to evaluate the performance of the suggested hybrid recommendation procedure. The main aim of this research Is to compare the hybrid recommendation algorithm with the CB algorithm. To evaluate the performance of each algorithm, we compare the purchased new item list in test period with the recommended item list which is recommended by suggested algorithms. So we employ the evaluation metric to hit the ratio for evaluating our algorithms. The hit ratio is defined as the ratio of the hit set size to the recommended set size. The hit set size means the number of success of recommendations in our experiment, and the test set size means the number of purchased items during the test period. Experimental test result shows the hit ratio of BC and NC is bigger than that of TC. This means using neighbors Is more effective to recommend new items. That is hybrid algorithm using CF is more effective when recommending to consumers new items than the algorithm using only CB. The reason of the smaller hit ratio of BC than that of NC is that BC is defined as a dummy or virtual customer who purchased all items of target customers' and neighbors'. That is centroid of BC often shifts from that of TC, so it tends to reflect skewed characters of target customer. So the recommendation algorithm using NC shows the best hit ratio, because NC has sufficient information about target customers and their neighbors without damaging the information about the target customers.