Probabilistic safety assessment-based importance analysis of cyber-attacks on nuclear power plants

With the application of digital technology to safety-critical infrastructures, cyber-attacks have emerged as one of the new dangerous threats. In safety-critical infrastructures such as a nuclear power plant (NPP), a cyber-attack could have serious consequences by initiating dangerous events or rendering important safety systems unavailable. Since a cyber-attack is conducted intentionally, numerous possible cases should be considered for developing a cyber security system, such as the attack paths, methods, and potential target systems. Therefore, prior to developing a risk-informed cyber security strategy, the importance of cyber-attacks and significant critical digital assets (CDAs) should be analyzed. In this work, an importance analysis method for cyber-attacks on an NPP was proposed using the probabilistic safety assessment (PSA) method. To develop an importance analysis framework for cyber-attacks, possible cyber-attacks were identified with failure modes, and a PSA model for cyber-attacks was developed. For case studies, the quantitative evaluations of cyber-attack scenarios were performed using the proposed method. By using quantitative importance of cyber-attacks and identifying significant CDAs that must be defended against cyber-attacks, it is possible to develop an efficient and reliable defense strategy against cyber-attacks on NPPs

Proto-type installation of a double-station system for the optical-video-detection and orbital characterisation of a meteor/fireball in South Korea

We give a detailed description of the installation and operation of a double-station meteor detection system which formed part of a research & education project between Korea Astronomy Space Science Institute and Daejeon Science Highschool. A total of six light-sensitive CCD cameras were installed with three cameras at SOAO and three cameras at BOAO observatory. A double-station observation of a meteor event enables the determination of the three-dimensional orbit in space. This project was initiated in response to the Jinju fireball event in March 2014. The cameras were installed in October/November 2014. The two stations are identical in hardware as well as software. Each station employes sensitive Watec-902H2 cameras in combination with relatively fast f/1.2 lenses. Various fields of views were used for measuring differences in detection rates of meteor events. We employed the SonotaCo UFO software suite for meteor detection and their subsequent analysis. The system setup as well as installation/operation experience is described and first results are presented. We also give a brief overview of historic as well as recent meteor (fall) detections in South Korea. For more information please consult http://meteor.kasi.re.kr .Comment: Technical/instrumentation description of a professional meteor detection system, 23 pages, 20 figures (color/monochrome), 5 tables, submitted to the Journal of Korean Astronomical Society (JKAS, http://jkas.kas.org/, http://jkas.kas.org/history.html

Generalized gravity model for human migration

The gravity model (GM) analogous to Newton's law of universal gravitation has successfully described the flow between different spatial regions, such as human migration, traffic flows, international economic trades, etc. This simple but powerful approach relies only on the 'mass' factor represented by the scale of the regions and the 'geometrical' factor represented by the geographical distance. However, when the population has a subpopulation structure distinguished by different attributes, the estimation of the flow solely from the coarse-grained geographical factors in the GM causes the loss of differential geographical information for each attribute. To exploit the full information contained in the geographical information of subpopulation structure, we generalize the GM for population flow by explicitly harnessing the subpopulation properties characterized by both attributes and geography. As a concrete example, we examine the marriage patterns between the bride and the groom clans of Korea in the past. By exploiting more refined geographical and clan information, our generalized GM properly describes the real data, a part of which could not be explained by the conventional GM. Therefore, we would like to emphasize the necessity of using our generalized version of the GM, when the information on such nongeographical subpopulation structures is available.Comment: 14 pages, 6 figures, 2 table

Emergent localized states at the interface of a twofold PT\mathcal{PT}-symmetric lattice

We consider the role of non-triviality resulting from a non-Hermitian Hamiltonian that conserves twofold PT-symmetry assembled by interconnections between a PT-symmetric lattice and its time reversal partner. Twofold PT-symmetry in the lattice produces additional surface exceptional points that play the role of new critical points, along with the bulk exceptional point. We show that there are two distinct regimes possessing symmetry-protected localized states, of which localization lengths are robust against external gain and loss. The states are demonstrated by numerical calculation of a quasi-1D ladder lattice and a 2D bilayered square lattice.Comment: 10 pages, 7 figure

Determinants of Competitive Advantage for Sport Firms: Using Public Big Data in Korea

This study examines the determinants of competitive advantage with respect to economic performance of sport firms. Logit regressions estimated dependent variables of economic performance measures based on sales per capita of firms. Determinants of competitive advantage were estimated by efficiency indicators, organization characteristic indicators, and industry classification indicators. Increase in efficiency was a significant determinant of competitive advantage as well as organizational type, size of human resource, diversification of products, and sales growth rate. Operationalizing competitive advantage as outperforming the market average and better than the top 10%, the logit regression model provides means for sport firms to analyze industry data to evaluate their own performance. In particular, including efficiency estimates showed practical significance for market analysis

Financial Performance of Healthcare Firms: The Case of Korea

The purpose of this study is to analyze the financial performance and financial characteristics of healthcare companies. Healthcare firms are statistically  significantly higher than non-healthcare companies in terms of several ratios such as research and development (R and D) cost ratio, selling general and administrative expenses ratio, Tobin's Q, return on equity, return on sales, total capital growth and sales growth. The cost of sales ratio is statistically lower than that of non-healthcare companies, which implies that healthcare companies spend much R and D costs for technological innovation, and as a result, they increase corporate value by lowering the cost of sales ratio and improving profitability. The profitability, growth, and leverage of healthcare companies were found to influence more on corporate value for the healthcare firms than those of non-healthcare companies. This result can be interpreted as reflecting the expectation that future cash flow will be more influenced by profitability, growth, and leverage of healthcare companies. Keywords: Healthcare, Healthcare Firms, Financial Performance JEL Classifications: I11, I32

Bacteriophages reduce Yersinia enterocolitica contamination of food and kitchenware

Yersinia enterocolitica, the primary cause of yersiniosis, is one of the most important foodborne pathogens globally and is associated with the consumption of raw contaminated pork. In the current study, four virulent bacteriophages (phages), one of Podoviridae (fHe-Yen3-01) and three of Myoviridae (fHe-Yen9-01, fHe-Yen9-02, and fHe-Yen9-03), capable of infecting Y. enterocolitica were isolated and characterized. fHe-Yen9-01 had the broadest host range (61.3% of strains, 65/106). It demonstrated a latent period of 35 min and a burst size of 33 plague-forming units/cell, and was found to have a genome of 167,773 bp with 34.79% GC content. To evaluate the effectiveness of phage fHe-Yen9-01 against Y. enterocolitica 0:9 strain Ruokola/71, we designed an experimental model of the food market environment. Phage treatment after bacterial inoculation of food samples, including raw pork (4 degrees C, 72 h), ready-to-eat pork (26 degrees C, 12 h), and milk (4 degrees C, 72 h), prevented bacterial growth throughout the experiments, with counts decreasing by 1-3 logs from the original levels of 2-4 x 10(3) CFU/g or ml. Similarly, when artificially contaminated kitchen utensils, such as wooden and plastic cutting boards and knives, and artificial hands, were treated with phages for 2 h, bacterial growth was effectively inhibited, with counts decreasing by 1-2 logs from the original levels of ca 10(4) CFU/cm(2) or ml. To the best of our knowledge, this is the first report of the successful application of phages for the control of Y. enterocolitica growth in food and on kitchen utensils.Peer reviewe

Increasing trend in rhegmatogenous retinal detachment in Korea from 2004 to 2015

Background To determine the 12-year incidence of and trends in rhegmatogenous retinal detachment (RRD) requiring surgery in Korea. Methods This was a nationwide, population-based, retrospective study. We identified 53,179 patients with incident RRD requiring surgery using the Korean National Health Claims Database from 2004 to 2015. We estimated the crude incidence rates and age- and sex-standardized incidence rates per 100,000 person-years in each year during the study period. A joinpoint regression analysis was performed to determine the trend. Results The average annual incidence rate was 9.78 (95% CI: 9.70–9.86). Male patients showed an incidence rate (10.68 [95% CI: 10.57–10.80]) 1.20 times that of female patients (8.87 [95% CI: 8.76–8.98]). The incidence showed a bimodal distribution; the highest peak was in the 60–64 year age group (23.77 [95% CI: 23.18–24.35]) and the second peak was in the 20–24 year age group (7.68 [95% CI: 7.41–7.95]). An increasing trend of RRD incidence was observed in the total population throughout the study period using joinpoint analysis (annual percentage change [APC], 2.05; 95% CI: 0.7–3.4). The increasing trend was more prominent among individuals aged under 50 years (APC, 3.44; 95% CI: 2.3–4.6), while among those aged 50 years or above, the increasing incidence was observed only in male patients. Conclusions In Korea, the incidence of RRD has increased recently. People in the < 50 year age group accounted for the major part of this significant increase, which is related to the increasing incidence of myopia in the young generation in Asia.This research was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health and Welfare, Republic of Korea (Grant Number: HI19C0373)

Effective promotions through social media: A case of Major League Baseball teams

This study examined if the impacts of Facebook promotions on fan engagement were moderated by team performance in the Major League Baseball. Two teams showing the opposite results in the 2015 seasons were selected. Likes, Shares, and Comments were measured as indicators of fan engagement. All posts were categorised in the five promotion types. A two-way MANOVA was carried out to see if there were any differences in Facebook Likes, Shares, and Comments for differing promotion types and team performance. The results revealed that there were statistically significant interaction effects between promotion types and team performance on Likes and Shares. For player/personnel promotion and team information, the numbers of Likes and Shares were significantly higher than the other promotion types for both teams. For Likes and Shares by the two significant promotion types, Royals had significantly higher mean scores than did Phillies

Detection of Internal Short Circuit in Lithium Ion Battery Using Model-Based Switching Model Method

Early detection of an internal short circuit (ISCr) in a Li-ion battery can prevent it from undergoing thermal runaway, and thereby ensure battery safety. In this paper, a model-based switching model method (SMM) is proposed to detect the ISCr in the Li-ion battery. The SMM updates the model of the Li-ion battery with ISCr to improve the accuracy of ISCr resistance R-ISCf estimates. The open circuit voltage (OCV) and the state of charge (SOC) are estimated by applying the equivalent circuit model, and by using the recursive least squares algorithm and the relation between OCV and SOC. As a fault index, the R-ISCf is estimated from the estimated OCVs and SOCs to detect the ISCr, and used to update the model; this process yields accurate estimates of OCV and R-ISCf. Then the next R-ISCf is estimated and used to update the model iteratively. Simulation data from a MATLAB/Simulink model and experimental data verify that this algorithm shows high accuracy of R-ISCf estimates to detect the ISCr, thereby helping the battery management system to fulfill early detection of the ISCr.119sciescopu