• Journal of the Korea Society of Computer and Information
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• v.21 no.6
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• pp.9-19
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• 2016

In finance literature, stock liquidity showing how stocks can be cashed out in the market has received rich attentions from both academicians and practitioners. The reasons are plenty. First, it is known that stock liquidity affects significantly asset pricing. Second, macroeconomic announcements influence liquidity in the stock market. Therefore, stock liquidity itself affects investors' decision and managers' decision as well. Though there exist a great deal of literature about stock liquidity in finance literature, it is quite clear that there are no studies attempting to investigate the stock liquidity issue as one of decision making problems. In finance literature, most of stock liquidity studies had dealt with limited views such as how much it influences stock price, which variables are associated with describing the stock liquidity significantly, etc. However, this paper posits that stock liquidity issue may become a serious decision-making problem, and then be handled by using data mining techniques to estimate its future extent with statistical validity. In this sense, we collected financial data set from a number of manufacturing companies listed in KRX (Korea Exchange) during the period of 2010 to 2013. The reason why we selected dataset from 2010 was to avoid the after-shocks of financial crisis that occurred in 2008. We used Fn-GuidPro system to gather total 5,700 financial data set. Stock liquidity measure was computed by the procedures proposed by Amihud (2002) which is known to show best metrics for showing relationship with daily return. We applied five data mining techniques (or classifiers) such as Bayesian network, support vector machine (SVM), decision tree, neural network, and ensemble method. Bayesian networks include GBN (General Bayesian Network), NBN (Naive BN), TAN (Tree Augmented NBN). Decision tree uses CART and C4.5. Regression result was used as a benchmarking performance. Ensemble method uses two types-integration of two classifiers, and three classifiers. Ensemble method is based on voting for the sake of integrating classifiers. Among the single classifiers, CART showed best performance with 48.2%, compared with 37.18% by regression. Among the ensemble methods, the result from integrating TAN, CART, and SVM was best with 49.25%. Through the additional analysis in individual industries, those relatively stabilized industries like electronic appliances, wholesale & retailing, woods, leather-bags-shoes showed better performance over 50%.

• Information Systems Review
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• v.24 no.1
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• pp.1-19
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• 2022

Social media-based communication has become crucial part of our personal and official lives. Therefore, it is no surprise that social media sentiment analysis has emerged an important way of detecting potential customers' sentiment trends for all kinds of companies. However, social media sentiment analysis suffers from huge number of sentiment features obtained in the process of conducting the sentiment analysis. In this sense, this study proposes a novel method by using Bayesian Network. In this model MBFS (Markov Blanket-based Feature Selection) is used to reduce the number of sentiment features. To show the validity of our proposed model, we utilized online review data from Yelp, a famous social media about restaurant, bars, beauty salons evaluation and recommendation. We used a number of benchmarking feature selection methods like correlation-based feature selection, information gain, and gain ratio. A number of machine learning classifiers were also used for our validation tasks, like TAN, NBN, Sons & Spouses BN (Bayesian Network), Augmented Markov Blanket. Furthermore, we conducted Bayesian Network-based what-if analysis to see how the knowledge map between target node and related explanatory nodes could yield meaningful glimpse into what is going on in sentiments underlying the target dataset.

• Information Systems Review
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• v.19 no.4
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• pp.183-209
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• 2017

With changes in information technology (IT), many innovative IT-based services, such as AirBnB, have become popular. Switching behavior toward new and innovative services become a major issue for managers who want to attract many customers. In response, many researchers have investigated why customers switch service providers. However, little research has been conducted on the processes of switching behavior for a hedonic service. To fill this research gap, this study aimed to identify the stages of switching behavior based on transtheoretical model. Furthermore, the factors affecting the service switching behavior in stages were identified on the basis of service provider switching model. This study also hypothesized the customer's switching behavior in accommodation sharing economy service and analyzed it empirically. Results showed that the factors affecting switching behavior differ across five stages. The present results can provide a basis to prevent switching behavior and reduce churn by analyzing the difference in switching behavior among stages. This study also helps managers who want to improve organizational performance by enhancing customer retention capability.

• Information Systems Review
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• v.25 no.1
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• pp.233-255
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• 2023

The development of information technology(IT) has brought so-called "online experience" to satisfy our daily needs. The market for online experiences grew more during the COVID-19 pandemic. Therefore, this study attempted to analyze how the features of online experience services affect customer satisfaction by crawling structured and unstructured data from the online experience web site newly launched by Airbnb after COVID-19. As a result of the analysis, it was found that the structured data generated by service users on a C2C online sharing platform had a positive effect on the satisfaction of other users. In addition, unstructured text data such as experience introductions and host introductions generated by service providers turned out to have different subjectivity scores depending on the purpose of its text. It was confirmed that the subjective host introduction and the objective experience introduction affect customer satisfaction positively. The results of this study are to provide various implications to stakeholders of the online sharing economy platform and researchers interested in online experience knowledge management.

• Journal of Embryo Transfer
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• v.14 no.1
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• pp.17-22
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• 1999

To investigate the maturational and development competece of porcine oocytes of different diameter groups, oocytes were obtained by aspiration from slaughterdhouse ovaries. After washing three times in NCSU23 medium, each cumulus-oocyte complex was transferred into a $8{mu}ell$ drop of the maturation medium (one oocyte per drop) under paraffin oil. The diameter without zona pellucida of oocytes was measured with micor-calibrator (Mikrometer, E. Leitz) on a screen connected to a VCR on an inverted microscope $(200\times)$. After being measured, the oocytes were divided into 6 groups according to their diameter size : <105, 105 to < 110, 110 to < 115, 115 to < 120, 120 to < 125 and > $125{\mu}{\textrm}{m}$, and in vitro maturation (IVM), fertillzation (IVF) and production (IVP) of oocytes / embryo was performed. The rates of in vitro maturation on oocytes in the greater 105 ${\mu}{\textrm}{m}$ size groups(91.8~100%) were significantly (P<0.05) higher than in the < 105 ${\mu}{\textrm}{m}$ group(66.7%). The rates of sperm penetration were significantly (P<0.05) low in < $105{\mu}{\textrm}{m}$ group (50.0%) than others groups (81.6~85.5%). But the plyspermic fertilization rate was significantly (P<0.05) higher in < $110{\mu}{\textrm}{m}$ oocytes groups than in the $110\leq{\mu}{\textrm}{m}$ size groups. The rates of cleavage and development to blastocysts rose as oocytes diameter increased, however, while oocytes over $120{\mu}{\textrm}{m}$ in diameter failed to develop to blastocysts. There results suggest that porcine oocytes have acquired full meiotic competece at a diameter of $105{\mu}{\textrm}{m}$ but not yet attended full development competence to blastocyst and that oocytes have acquired full development competence at a diameter of $110{\mu}{\textrm}{m}$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.3
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• pp.197-204
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• 2005

The major symptom such as yellowish and mosaic spots in overwintering barley were mostly caused by viruses such as Barley yellow mosaic virus (BaYMV) and Barley mild mosaic virus (BaMMV) in the nation-wide for four years. The result showed that more than $78\%$ collected samples were infected by the viruses. The incidence of Ba YMV was more than $70\%$, and relatively uniformly distributed in the southern regions of barley fields in Korea. However the incidence of BaYMV in Gyeonggi Province was as low as $19\%$ compared to $65\~85\%$ in the rest of regions. Occurrence of BaMMV varied depending on investigated regions such as $20\~40\%$ in Jeonbuk, Jeonnam, Gangwon and Gyeongnam, and a lower infection in Gyeongbuk, Chungnam and Gyeonggi Provinces. In this result, $60\%$ of BaMMV was found to be in the southwest regions of Korea such as Jeonbuk and Jeonnam Provinces. Over all, both BaYMV and BaMMV were thought to be dominantly casual agents in overwintering barley by either solely or mixed infections. Soil-borne wheat mosaic virus(SBWMV) occurred at most $14\%$ in Gyeonggi and Barley yellow dwarf virus-MAY (BYDV­MAV) was found only one place in Jeonbuk, suggesting that SBWMV and BYDV-MAV were not significant diseases in Korea. Exotic genetic resources that possess different resistant genes to BaYMV and BaMMV were tested to identify the responses to the viruses occurred in Iksan. According to the ELISA results, BaYMV and BaMMV were infected in some plant materials but SBWMV was not identified. Any resistant gene was not effective to BaYMV-Ik (Insan strain) and BaMMY. Ishukushirazu (rym 3) and Chosen (rym 3), Tokushima Mochi Hadaka (rym 4y) and Hakei 1-41 (rym 5a) showed resistant response with little symptoms to BaYMY. The other five accessions possessing rym 1+5, rym 2, rym 4m, rym 5 and rym 9, respectively, were resistant to BaMMV. Various symptoms were observed in the tested plant materials such as not only yellowish and mosaic symptoms mostly but also necrotic spot, tissue necrosis, leaf stripe and leaf curling. However, it was difficult to find any relationship between resistant genes and specific symptoms.

• Journal of Korean society of Dental Hygiene
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• v.2 no.2
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• pp.175-186
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• 2002

Fluoride has been one of the most widely studied caries-preventive agents. But the effect of prenatal administration had been controversies for many years. The results showed that there were no influence on reproductive rate of rats with administration of fluoride from 0 to 20 ppm during pregnancy(p>0.05). There was a trend towards slightly increased the mean ash weight in the 1, 5 and 20 ppm groups, as compared with the control group. However, there was no significant differences among groups (p>0.05). The contents of calcium, magnesium and phosphorus in the total bone were increased with the administrated fluoride concentration were increased, but there were no statistically significant differences among groups(p>0.05). The mean fluoride level of 1 ppm group was significantly higher than that of control group, but the concentrations of fluoride in total carcass pups of 5 and 20 ppm groups were significantly less than that of 1 ppm group(p>0.05). The results of this study indicate that the amount of fluoride transferred to the offspring, which may produce anticariogenic effects in the primary teeth of their effects in the primary teeth of their offspring.

• Tuberculosis and Respiratory Diseases
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• v.47 no.4
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• pp.478-487
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• 1999

Background : Differential diagnosis of pleural malignant mesothelioma from secondary metastatic adenocarcinoma is often difficult. A variety of pathologic techniques have been developed to make a differential diagnosis of carcinoma from mesothelioma. Immunohistochemistry detecting diverse antigenic substances such as CEA, Leu-M1, Bn-3, S-100 protein, vimentin, CK and EMA has been claimed to be of value as a panel in the differential diagnosis of adenocarcinoma from mesothelioma. The aim of this study was to investigate the suitable antibodies to distinguish mesothelioma from metastatic adenocarcinoma and establish candidate markers in a panel. Methods : Complete, one-hour immunohistochemical staining using antibodies against cytokeratin (CK), epithelial membrane antigen(EMA), S-100 protein, vimentin, B72-3, Leu-M1, and carcino-embryonic antigen(CEA) was applied to cell blocks from 7 mesotheliomas and 7 adenocarcinomas which were confirmed by electron microscopic and histpathologic methods. Results : All adenocarcinomas and 71.4% of mesotheliomas expressed the cytokeratin and EMA. S-100 protein and vimentin were expressed in 57.1% and 42.9% of mesotheliomas and 14.3% and 28.5% of adenocarcinomas, respectively. B72-3 was expressed in all adenocarcinomas, but in none of mesotheliomas. Leu-M1 was positive in 71.4% of the adenocarcinoma and 14.3% of the mesotheliomas. CEA was positive in all adenocarcinomas and 42.9% of mesotheliomas. Leu-M1 and B72-3 were coexpressed in 71.4% of adenocarcinomas but in none of mesothelioma. B72-3 and CEA were coexpressed in all adenocarcinomas, but in none of mesotheliomas. Conclusion : We concluded that B72-3 immunohistochemistry or panel staining of B72-3 and CEA could be recommanded for the differential diagnosis of pleural mesothelioma from metastatic adenocarcinoma.

• The Korean Journal of Mycology
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• v.49 no.1
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• pp.87-100
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• 2021

This study aimed to isolate wild yeasts obtained from flowers and soil of the Wolpyung park, Daejeon city and Gykpo beach, Buan, Jeollabuk-do in Korea, and to further characterize previously unrecorded wild yeast strains. In total, 88 strains of 62 different species of wild yeasts were isolated from 75 samples obtained from the Wolpyung park. Among these, six strains of Trichosporon moniliiforme and four strains each of Papiliotrema flavescens and Candida melibiosica were isolated. Additionally, 39 strains of 30 different species of wild yeasts were isolated from 35 samples collected from the Gykpo beach. Among the 127 isolated wild yeast strains, 10 strains, including Apiotrichum porosum ASCM32-1, were previously unrecorded. All the 10 previously unrecorded yeasts were oval or global in shape, and three strains, including Candida athensensis WP4-90-3, formed spores. Three strains, including Vishniacozyma taibaiensis WP13-2, were halophilic yeasts which grew in 15% NaCl-containing YPD(yeast extract-peptone-dextrose) medium. Five strains, including C. athensensis WP4-90-3, showed 15% ethanol resistance. Cell-free extracts from Candida oleophila WP5-19-1 and Wickerhamomyces anomalus HO9-2 showed the highest β-glucuronidase inhibitory activity (49.0%) and neutrophil elastase inhibitory activity (38.4%), respectively.

• Explosives and Blasting
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• v.9 no.1
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• pp.3-13
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• 1991

The cautious blasting works had been used with emulsion explosion electric M/S delay caps. Drill depth was from 3m to 6m with Crawler Drill ${\phi}70mm$ on the calcalious sand stone (soft -modelate -semi hard Rock). The total numbers of test blast were 88. Scale distance were induced 15.52-60.32. It was applied to propagation Law in blasting vibration as follows. Propagtion Law in Blasting Vibration $V=K(\frac{D}{W^b})^n$ were V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites(m) W : Maximum charge per delay-period of eight milliseconds or more (kg) K : Ground transmission constant, empirically determind on the Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents where the quantity $\frac{D}{W^b}$ is known as the scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagorized in three groups. Cubic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge Per delay Plots of peak particle velocity versus distoance were made on log-log coordinates. The data are grouped by test and P.P.V. The linear grouping of the data permits their representation by an equation of the form ; $V=K(\frac{D}{W^{\frac{1}{3}})^{-n}$ The value of K(41 or 124) and n(1.41 or 1.66) were determined for each set of data by the method of least squores. Statistical tests showed that a common slope, n, could be used for all data of a given components. Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom over loom distance because the frequency is verified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m ------- under l00m ${\cdots\cdots\cdots}{\;}41(D/sqrt[2]{W})^{-1.41}{\;}{\cdots\cdots\cdots\cdots\cdots}{\;}A$ Over 100m ${\cdots\cdots\cdots\cdots\cdots}{\;}121(D/sqrt[3]{W})^{-1.66}{\;}{\cdots\cdots\cdots\cdots\cdots}{\;}B$ where ; V is peak particle velocity In cm / sec D is distance in m and W, maximLlm charge weight per day in kg K value on the above equation has to be more specified for further understaring about the effect of explosives, Rock strength. And Drilling pattern on the vibration levels, it is necessary to carry out more tests.