• The Journal of Society for e-Business Studies
• /
• v.17 no.4
• /
• pp.69-93
• /
• 2012

Various influence-related relationships in Social Network Services (SNS) among users, posts, and user-and-post, can be expressed using links. The current research evaluates the influence of specific users or posts by analyzing the link structure of relevant social network graphs to identify influential users. We applied the concept of mutual interactions proposed for ranking semantic web resources, rather than the voting notion of Page Rank or HITS, to blogosphere, one of the early SNS. Through many experiments with network models, where the performance and validity of each alternative approach can be analyzed, we showed the applicability and strengths of our approach. The weight tuning processes for the links of these network models enabled us to control the experiment errors form the link weight differences and compare the implementation easiness of alternatives. An additional example of how to enter the content scores of commercial or spam posts into the graph-based method is suggested on a small network model as well. This research, as a starting point of the study on identifying influential users in SNS, is distinctive from the previous researches in the following points. First, various influence-related properties that are deemed important but are disregarded, such as scraping, commenting, subscribing to RSS feeds, and trusting friends, can be considered simultaneously. Second, the framework reflects the general phenomenon where objects interacting with more influential objects increase their influence. Third, regarding the extent to which a bloggers causes other bloggers to act after him or her as the most important factor of influence, we treated sequential referencing relationships with a viewpoint from that of PageRank or HITS (Hypertext Induced Topic Selection).

• Journal of Intelligence and Information Systems
• /
• v.25 no.1
• /
• pp.85-107
• /
• 2019

Online consumers browse products belonging to a particular product line or brand for purchase, or simply leave a wide range of navigation without making purchase. The research on the behavior and purchase of online consumers has been steadily progressed, and related services and applications based on behavior data of consumers have been developed in practice. In recent years, customization strategies and recommendation systems of consumers have been utilized due to the development of big data technology, and attempts are being made to optimize users' shopping experience. However, even in such an attempt, it is very unlikely that online consumers will actually be able to visit the website and switch to the purchase stage. This is because online consumers do not just visit the website to purchase products but use and browse the websites differently according to their shopping motives and purposes. Therefore, it is important to analyze various types of visits as well as visits to purchase, which is important for understanding the behaviors of online consumers. In this study, we explored the clustering analysis of session based on click stream data of e-commerce company in order to explain diversity and complexity of search behavior of online consumers and typified search behavior. For the analysis, we converted data points of more than 8 million pages units into visit units' sessions, resulting in a total of over 500,000 website visit sessions. For each visit session, 12 characteristics such as page view, duration, search diversity, and page type concentration were extracted for clustering analysis. Considering the size of the data set, we performed the analysis using the Mini-Batch K-means algorithm, which has advantages in terms of learning speed and efficiency while maintaining the clustering performance similar to that of the clustering algorithm K-means. The most optimized number of clusters was derived from four, and the differences in session unit characteristics and purchasing rates were identified for each cluster. The online consumer visits the website several times and learns about the product and decides the purchase. In order to analyze the purchasing process over several visits of the online consumer, we constructed the visiting sequence data of the consumer based on the navigation patterns in the web site derived clustering analysis. The visit sequence data includes a series of visiting sequences until one purchase is made, and the items constituting one sequence become cluster labels derived from the foregoing. We have separately established a sequence data for consumers who have made purchases and data on visits for consumers who have only explored products without making purchases during the same period of time. And then sequential pattern mining was applied to extract frequent patterns from each sequence data. The minimum support is set to 10%, and frequent patterns consist of a sequence of cluster labels. While there are common derived patterns in both sequence data, there are also frequent patterns derived only from one side of sequence data. We found that the consumers who made purchases through the comparative analysis of the extracted frequent patterns showed the visiting pattern to decide to purchase the product repeatedly while searching for the specific product. The implication of this study is that we analyze the search type of online consumers by using large - scale click stream data and analyze the patterns of them to explain the behavior of purchasing process with data-driven point. Most studies that typology of online consumers have focused on the characteristics of the type and what factors are key in distinguishing that type. In this study, we carried out an analysis to type the behavior of online consumers, and further analyzed what order the types could be organized into one another and become a series of search patterns. In addition, online retailers will be able to try to improve their purchasing conversion through marketing strategies and recommendations for various types of visit and will be able to evaluate the effect of the strategy through changes in consumers' visit patterns.

• Journal of Chest Surgery
• /
• v.37 no.12
• /
• pp.967-977
• /
• 2004

Background: DNA methylation is one of the important gene expression mechanisms of the cell. When cytosine of CpG dinucleotide in promotor is hypomethylated, expression of some genes that is controlled by this promoter is altered. In this study, the author investigated the effect of DNA demethylating agent, 5-aza-2'-deoxycytidine (ADC), on the expressions of cancer antigen genes, MHC and B7 in 4 lung cancer cell lines, NCIH1703, NCIH522, MRC-5, and A549. Material and Method: After treatment of cell lines, NCIH1703, NCIH522, MRC-5 and A549 with ADC (1 uM) for 48 hours, RT-PCR was performed by using the primers of MAGE, GAGE, NY-ESO-1, PSMA, CEA, and SCC antigen gene. In order to find the optimal ADC treatment condition for induction of cancer antigen, we studied the effect of ADC treatment time and dose on the cancer antigen gene expression. To know the effect of ADC on the expression of MHC or B7 and cell growth, cells were treated with 1 uM of ADC for 72 hours for FACS analysis or cells were treated with 0.2, 1 or 5 uM of ADC for 96 hours for cell counting. Result: After treatment of ADC (1 uM) for 48 hours, the expressions of MAGE, GAGE, NY-ESO-1, and PSMA genes increased in some cell lines. Among 6 MAGE isotypes tested, and gene expression of MAGE-1, -2, -3, -4 and -6 could be induced by ADC treatment. However, CEA gene expression did not change and SCC gene expression was decreased by ADC treatment. Gene expression was generally induced 24 - 28 hours after ADC treatment and expression of MAGE, GAGE, and NY-ESO-1 was maintained at least 14 days after ADC ADC teatment, and expression of MAGE, GAGE, and NY-ESO-1 was maintained at least 14 days after ADC teatment in ADC-Free medium. Most gene expression could be induced at 0.2 uM of ADC, but gene expression increased dependently on ADC treatment dose. The expression of MHC and B7 was not increased by ADC treatment in all four cell lines, and the growth rate of 4 cell lines decreased significantly with the increase of ADC concentrations. Conclusion: Treatment of lung cancer cell lines with ADC increases the gene expression MAGE, GAGE and NY-ESO-1 that are capable of induction of cytotoxic T lymphocyte response. We suggest that treatment with 1 uM of ADC for 48 hours and then culturing in ADC-free medium is optimal condition for induction of cancer antigen. However, ADC has no effect on MHC and B7 induction, additional modification for increase of expression of MHC, B7 and cytokine will be needed for production of efficient cancer cell vaccine.

• Journal of Intelligence and Information Systems
• /
• v.20 no.1
• /
• pp.195-211
• /
• 2014

Cloud computing services provide IT resources as services on demand. This is considered a key concept, which will lead a shift from an ownership-based paradigm to a new pay-for-use paradigm, which can reduce the fixed cost for IT resources, and improve flexibility and scalability. As IT services, cloud services have evolved from early similar computing concepts such as network computing, utility computing, server-based computing, and grid computing. So research into cloud computing is highly related to and combined with various relevant computing research areas. To seek promising research issues and topics in cloud computing, it is necessary to understand the research trends in cloud computing more comprehensively. In this study, we collect bibliographic information and citation information for cloud computing related research papers published in major international journals from 1994 to 2012, and analyzes macroscopic trends and network changes to citation relationships among papers and the co-occurrence relationships of key words by utilizing social network analysis measures. Through the analysis, we can identify the relationships and connections among research topics in cloud computing related areas, and highlight new potential research topics. In addition, we visualize dynamic changes of research topics relating to cloud computing using a proposed cloud computing "research trend map." A research trend map visualizes positions of research topics in two-dimensional space. Frequencies of key words (X-axis) and the rates of increase in the degree centrality of key words (Y-axis) are used as the two dimensions of the research trend map. Based on the values of the two dimensions, the two dimensional space of a research map is divided into four areas: maturation, growth, promising, and decline. An area with high keyword frequency, but low rates of increase of degree centrality is defined as a mature technology area; the area where both keyword frequency and the increase rate of degree centrality are high is defined as a growth technology area; the area where the keyword frequency is low, but the rate of increase in the degree centrality is high is defined as a promising technology area; and the area where both keyword frequency and the rate of degree centrality are low is defined as a declining technology area. Based on this method, cloud computing research trend maps make it possible to easily grasp the main research trends in cloud computing, and to explain the evolution of research topics. According to the results of an analysis of citation relationships, research papers on security, distributed processing, and optical networking for cloud computing are on the top based on the page-rank measure. From the analysis of key words in research papers, cloud computing and grid computing showed high centrality in 2009, and key words dealing with main elemental technologies such as data outsourcing, error detection methods, and infrastructure construction showed high centrality in 2010~2011. In 2012, security, virtualization, and resource management showed high centrality. Moreover, it was found that the interest in the technical issues of cloud computing increases gradually. From annual cloud computing research trend maps, it was verified that security is located in the promising area, virtualization has moved from the promising area to the growth area, and grid computing and distributed system has moved to the declining area. The study results indicate that distributed systems and grid computing received a lot of attention as similar computing paradigms in the early stage of cloud computing research. The early stage of cloud computing was a period focused on understanding and investigating cloud computing as an emergent technology, linking to relevant established computing concepts. After the early stage, security and virtualization technologies became main issues in cloud computing, which is reflected in the movement of security and virtualization technologies from the promising area to the growth area in the cloud computing research trend maps. Moreover, this study revealed that current research in cloud computing has rapidly transferred from a focus on technical issues to for a focus on application issues, such as SLAs (Service Level Agreements).

• The Korean Journal of Nuclear Medicine
• /
• v.37 no.6
• /
• pp.364-373
• /
• 2003

Purpose: For good quality of myocardial perfusion images, an approximately 30 min to 1 hour of waiting time after radiopharmaceutical injection and ingestion of fatty meal are asked of the patients. The aim of this study was to investigate the shortening of waiting time after radiopharmaceutical injection and improvement of image quality using natural plant extracts that promote bile excretion. Materials and Methods: Ten volunteers participated in protocol 1 (7 men, 3 women; mean age, $24.1{\pm}2.4$ years) and protocol 2 (8 men, 2 women; mean age, $26.1{\pm}2.9$ years), respectively. For the modified method of both protocols, subjects took natural plant extracts 15 minutes before the first injection of $^{99m}Tc$ MIBI without laking fatty meals. Control (Conventional) methods were peformed with intake of a fatty meal 20 to 30 minutes after $^{99m}Tc$ MIBI injection. Results: As the results of protocol 1 and 2, the ratio of myocardial to lung ratio were not different between modified and conventional method. Liver to lung ratio of modified method showed significantly lower value than that of conventional method. In modified method, myocardial to liver ratio was higher persistently. In protocol 2, natural plant extracts took before the first injection of $^{99m}Tc$ MIBI exerted accelerating effect of excretion of bile juice into Intestine until the end of examination. Conclusion: These results represent that natural plant extracts for facilitation of bile excretion before injection of $^{99m}Tc$ MIBI may provide better quality of myocardial perfusion images without the need for preparations such as ingestion of fatty meal within the 2 hours compared with conventional method.

• Radiation Oncology Journal
• /
• v.15 no.1
• /
• pp.37-47
• /
• 1997

Purpose : To investigate ultrastructural changes of the mouse lung induced by whole lung gamma irradiation and to evaluate the effect of prophylactic administration of steroid against acute lung injury. Materials and Methods :. One hundred and twenty ICR mice were used and whole lung was irradiated with telecobalt machine. Whole lung doses were 8 and 12Gy, and 10mg of methyl prednisolone was administrated intraperitoneally for two and four weeks. At the end of the observation period, mice were sacrificed by cervical dislocation. The lungs were removed and fixed inflated. Histopathological examination of acute radiation injuries were Performed by light microscopic and transmission electron microscopic examination. Results : Control group with BGy is characterized by damage to the type I Pneumocyte and the endothelial cell of the capillary. edema of alveolar wall and interstitium. and fibroblast proliferation. Control group with 120y is characterized by more severe degree of type 1 pneumocyte damage and more prominant inflammatory cell infiltration. Destructed cell debris within the alveolar space were also noted After steroid administration, 8Gy experimental group showed decreased degree of inflammatory reactions but fibroblast proliferation and basal lamina damages were unchanged. Experimental group with 12Gy showed lesser degree of inflammatory reactions similar to changes of 8Gy experimental group. Conclusion : These studies suggest that the degree of interstitial edema and inflammatory changes were related to radiation dose but Proliferation of the fibroblast and structural changes of basal lamina were not related to radialion dose. Experimental administration of steroid for 2 to 4 weeks after whole lung irradiation suggest that steroid can suppress alveolar and endothelial damages induced by whole lung irradiation but Proliferation of the fibroblast and structural changes of basal lamina were not related to administration of steroid.

• Journal of Chest Surgery
• /
• v.41 no.5
• /
• pp.591-597
• /
• 2008

Background: Pulmonary endarterectomy is widely accepted as a treatment for chronic thromboembolic pulmonary hypertension. Based on our experiences, we sought to find ways to reduce perioperative complications and to improve surgical outcomes in patients undergoing pulmonary endarterectomy. Material and Method: This study was designed as a retrospective analysis of 20 patients with pulmonary hypertension who underwent pulmonary endarterectomy between January 1998 and March 2008. All patients presented with chronic dyspnea. Deep vein thrombosis (DVT) was the major cause of chronic pulmonary thromboembolism (55%). Seventeen patients (85%) underwent inferior vena cava (IVC) filter placement. Thirteen patients underwent surgery under total circulatory arrest, while the others underwent surgery while on low flow cardiopulmonary bypass. Concomitant tricuspid annuloplasty was done in 6 patients (66%) whose tricuspid regurgitation was as severe as grade IV/IV. The mean follow-up duration was $45{\pm}32$ months. Result: Using of University of California, San Diego (UCSD), thromboembolism classification, 4 patients (20%) were type 1, 8 patients (40%) were type II, and 8 patients (40%) were type III. Right ventricular systolic pressure was reduced significantly from $77{\pm}29$ mmHg to $37{\pm}19$ mmHg after pulmonary endarterectomy (p<0.001). The degree of tricuspid regurgitation and the NYHA functional class were all improved postoperatively. Reperfusion edema occurred in 7 cases (35%). The incidence of reperfusion edema was higher in the UCSD type III group than in the other group (25% vs 50%, p=0.25) and the length of postoperative intensive care unit stay was longer in type III group ($5{\pm}2$ days vs $9{\pm}7$ days, p=0.07). The early mortality rate was 10%, and the late mortality rate was 15% (n=3); one death was due to progression of underlying non-Hodgkin's lymphoma, and the other deaths were related to recurrent thromboembolism and persistent pulmonary hypertension, respectively. Conclusion: Pulmonary endarterectomy, as a curative surgical method for treating chronic thromboernbolic pulmonary hypertension, should be performed aggressively in patients diagnosed with chronic thromboembolic pulmonary hypertension, and an effort should be made to reduce the frequency of perioperative complications and to improve surgical outcomes.

• The Transactions of the Korea Information Processing Society
• /
• v.5 no.10
• /
• pp.2575-2583
• /
• 1998

The productionof the highly relible softwae systems and theirs performance evaluation hae become important interests in the software industry. The software evaluation has been mainly carried out in ternns of both reliability and performance of software system. Software reliability is the probability that no software error occurs for a fixed time interval during software testing phase. These theoretical software reliability models are sometimes unsuitable for the practical testing phase in which a software error at a certain testing stage occurs by causes of the imperfect debugging, abnornal software correction, and so on. Such a certatin software testing stage needs to be considered as an outlying stage. And we can assume that the software reliability does not improve by means of muisance factor in this outlying testing stage. In this paper, we discuss Bavesian software reliability growth modeling and estimation procedure in the presence of an imidentitied outlying software testing stage by the modification of Jehnski Moranda. Also we derive the Bayes estimaters of the software reliability panmeters by the assumption of prior information under the squared error los function. In addition, we evaluate the proposed software reliability growth model with an unidentified outlying stage in an exchangeable model according to the values of nuisance paramether using the accuracy, bias, trend, noise metries as the quantilative evaluation criteria through the compater simulation.

• Tuberculosis and Respiratory Diseases
• /
• v.59 no.6
• /
• pp.613-618
• /
• 2005

Background : Recently, medical treatment of multi-drug resistant pulmonary tuberculosis has been unsuccessful. Through analyzing the cases with surgical treatment, we hope to provide some help in treating multi-drug resistant pulmonary tuberculosis in the future. Material and Method : A retrospective review was performed with 138cases of surgical treatment of multi-drug resistant tuberculosis during 10years from January 1994 to December 2003 at National Masan Hospital. Results : The ratio of men to women, 5.1:1 indicates that there were more incidences in men. The number of the resistant drugs was 5.3 with a mean age of 42.6 years. Cavitary lesions on the plain chest X-rays were seen in 94cases (68.1%). 128cases had positive sputum culture preoperatively. Types of operations were 24 pnemonectomies, 83 lobectomies, 10 bilobectomies, 19 lobectomies with segmentectomies or wedge resections, 1 wedge resection, and 1 carvenoplasty. There was no death after operation. There were 6cases of air leakage over a week, 6cases of postoperative bleeding, 8cases of bronchopleural fistula and empyema, 16cases of dead space, 1case of atelectasis, 1case of wound infection, 1case of cyst as postoperative complication. Postoperative complication showed higher long-term negative conversion rate of 92.8%. Conclusion : There has been many discussions about operative indications, postoperative drug regimens, length of postoperative chemotherapy. In our study, we showed higher long-term success rate of postoperative chemotherapy with pulmonary resection on multi-drug resistant pulmonary tuberculosis.

• Journal of Chest Surgery
• /
• v.36 no.8
• /
• pp.566-575
• /
• 2003

We reviewed our 18-year surgical experience of biventricular repair for double-outlet right ventricle. Material and Method: One hundred twelve consecutive patients (80 males and 32 females) who underwent biventricular repair for double-outlet right ventricle between May 1986 and September 2002 were included. We assessed risk factors for early mortality and reoperation. Reoperation-free survival rate and actual survival rate were analysed. Result: Most common type of ventricular septal defect was subaortic (n=58, 52%) and non-committed type was second most common (n=32, 29%). Four different surgical methods were used: intraventricular baffle repair (n=71 , 63%): right ventricle to pulmonary ariery conduit interposition or REV with left ventricle to aorta baffle repair (n=24, 21 .4%): arierial switch operation with left ventricle to pulmonary artery baffle (n=14, 12.5%): Senning atrial switch operation with left ventricle to pulmonary artery baffle (n=3, 2.7%). Thirty four patients(30%) underwent palliative procedures before definite repair. Twenty three patients (21%) required reoperations. There were 12 (10.7%) early deaths and 4 late deaths. Age younger than 3 months at repair (p=0.003), cardiopulmonary bypass and aortic cross clamp time (p=0.015, p=0.067), type of operation (arterial switch operation) (p <0.001) and type of ventricular septal defect (subpulmonic type) (p=0.002) were revealed as risk factors for early death in univariate analysis, while age under 3 months was the only significant risk factor in multivariate analysis. Patients younger than 1 year of age (p=0.02), pulmonary artery angioplasty at definitive repair (p=0.024), type of ventricular septal defect (non-committed) (p=0.001), type of operation (right ventricle to pulmonary artery conduit interposition and REV operation) (p=0.028, p=0.017) were risk factors for reoperation in univariate analysis but there was no significant risk factor in multivariate analysis. Follow-up was available on 91 survivals with a mean duration of 110.8$\pm$56.4 (2~201) months. 5, 10 and 15 year survival rates were 86.5%, 85% and 85% and reoperation free survival were 85%, 71.5%, 70%. Conclusion: Age under 3 months at repair, subpulmonic ventricular septal defect and arterial switch operation were significant risk factors for early mortality. Patients with non-committed ventricular septal defect and who underwent conduit interposition or REV operation were risk factors for reoperation. With careful attention to chose best timing and surgical approach depending on morphologic characteristics, biventricular repair for double outlet right ventricle can be achieved with good long-term outcome.