• Journal of Intelligence and Information Systems
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• v.21 no.2
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• pp.1-18
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• 2015

Collaborative filtering(CF) algorithm has been popularly used for recommender systems in both academic and practical applications. A general CF system compares users based on how similar they are, and creates recommendation results with the items favored by other people with similar tastes. Thus, it is very important for CF to measure the similarities between users because the recommendation quality depends on it. In most cases, users' explicit numeric ratings of items(i.e. quantitative information) have only been used to calculate the similarities between users in CF. However, several studies indicated that qualitative information such as user's reviews on the items may contribute to measure these similarities more accurately. Considering that a lot of people are likely to share their honest opinion on the items they purchased recently due to the advent of the Web 2.0, user's reviews can be regarded as the informative source for identifying user's preference with accuracy. Under this background, this study proposes a new hybrid recommender system that combines with users' review mining. Our proposed system is based on conventional memory-based CF, but it is designed to use both user's numeric ratings and his/her text reviews on the items when calculating similarities between users. In specific, our system creates not only user-item rating matrix, but also user-item review term matrix. Then, it calculates rating similarity and review similarity from each matrix, and calculates the final user-to-user similarity based on these two similarities(i.e. rating and review similarities). As the methods for calculating review similarity between users, we proposed two alternatives - one is to use the frequency of the commonly used terms, and the other one is to use the sum of the importance weights of the commonly used terms in users' review. In the case of the importance weights of terms, we proposed the use of average TF-IDF(Term Frequency - Inverse Document Frequency) weights. To validate the applicability of the proposed system, we applied it to the implementation of a recommender system for smartphone applications (hereafter, app). At present, over a million apps are offered in each app stores operated by Google and Apple. Due to this information overload, users have difficulty in selecting proper apps that they really want. Furthermore, app store operators like Google and Apple have cumulated huge amount of users' reviews on apps until now. Thus, we chose smartphone app stores as the application domain of our system. In order to collect the experimental data set, we built and operated a Web-based data collection system for about two weeks. As a result, we could obtain 1,246 valid responses(ratings and reviews) from 78 users. The experimental system was implemented using Microsoft Visual Basic for Applications(VBA) and SAS Text Miner. And, to avoid distortion due to human intervention, we did not adopt any refining works by human during the user's review mining process. To examine the effectiveness of the proposed system, we compared its performance to the performance of conventional CF system. The performances of recommender systems were evaluated by using average MAE(mean absolute error). The experimental results showed that our proposed system(MAE = 0.7867 ~ 0.7881) slightly outperformed a conventional CF system(MAE = 0.7939). Also, they showed that the calculation of review similarity between users based on the TF-IDF weights(MAE = 0.7867) leaded to better recommendation accuracy than the calculation based on the frequency of the commonly used terms in reviews(MAE = 0.7881). The results from paired samples t-test presented that our proposed system with review similarity calculation using the frequency of the commonly used terms outperformed conventional CF system with 10% statistical significance level. Our study sheds a light on the application of users' review information for facilitating electronic commerce by recommending proper items to users.

• Progress in Medical Physics
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• v.22 no.2
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• pp.99-105
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• 2011

The purpose of this study is to evaluate the accuracy of IMRT in our clinic from based on TG119 procedure and establish action level. Five IMRT test cases were described in TG119: multi-target, head&neck, prostate, and two C-shapes (easy&hard). There were used and delivered to water-equivalent solid phantom for IMRT. Absolute dose for points in target and OAR was measured by using an ion chamber (CC13, IBA). EBT2 film was utilized to compare the measured two-dimensional dose distribution with the calculated one by treatment planning system. All collected data were analyzed using the TG119 specifications to determine the confidence limit. The mean of relative error (%) between measured and calculated value was $1.2{\pm}1.1%$ and $1.2{\pm}0.7%$ for target and OAR, respectively. The resulting confidence limits were 3.4% and 2.6%. In EBT2 film dosimetry, the average percentage of points passing the gamma criteria (3%/3 mm) was $97.7{\pm}0.8%$. Confidence limit values determined by EBT2 film analysis was 3.9%. This study has focused on IMRT commissioning and quality assurance based on TG119 guideline. It is concluded that action level were ${\pm}4%$ and ${\pm}3%$ for target and OAR and 97% for film measurement, respectively. It is expected that TG119-based procedure can be used as reference to evaluate the accuracy of IMRT for each institution.

• The Korean Journal of Financial Management
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• v.20 no.1
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• pp.93-124
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• 2003

This paper studies the financial analyst's forecasting activities on the firm's operating performance during the period from 1999 to 2003. In this study, financial analyst's forecasting activities are focused on the sales, operating income and net income and financial analyst's forecasting accuracy, forecasting revising patterns and forecasting activities to the unexpected firm's operating performance are studied. Some empirical findings in this study are as follows. First, standard estimate error on the sales, operating income and net income are all significantly negative value and so financial analyst's forecast on the firm's operating performance are upwardly biased. Second, domestic financial analyst's forecasting activities is relatively more accuracy than foreign financial analyst's forecasting activities. Third, forecasting time is more close to the end of the operating performance announcement day, forecasting activities are more accuracy. Fourth, comparing with individual financial analyst's forecast, consensus forecast is more accuracy. Fifth, in the comparative forecasting activities study according to the prior firm's operating performance, financial analyst's forecasting revision activities are found to be upward or downward. Sixth, financial analysts overreact in the sales forecast and underreact in the operating income and net income forecast. Seventh, in the empirical analysis on the Easterwood-Nutt's test model(1999) which the firm's performance change are divided into the expected performance change and the unexpected performance change, it is found that financial analyst's forecasting activities on the firm's operating performance are systematically optimistic.

• Tuberculosis and Respiratory Diseases
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• v.60 no.4
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• pp.404-411
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• 2006

Purpose : Multidrug-resistant tuberculosis (MDR-TB) is an emerging threat to human beings. However, there is little data on the current status of MDR-TB in Korea. This study investigated the current status of MDR-TB in Korea using a survey of all the data from drug susceptibility tests (DST) performed across the country over the last three years. Method : The DST results between Jan. 2000 and Dec. 2002 from 7 laboratories, which were in charge of all antituberculous DSTs across the country as of March 2002, were collected and analyzed to determine the actual number of drug-resistant or MDR-TB patients, annual trend, degree and pattern of resistance against anti-TB drugs, etc. Results : Six laboratories used the absolute concentration method for DST and one used the proportional method. 59, 940 tests had been performed over the 3 year study period. The number of DST performed annually was 18,071, 19,950, and 21,919 in 2000-2002, respectively. The number of resistant tuberculosis patients (resistant against at least one anti-TB drug) had increased by 16.9% from 6,338 in 2000 to 7,409 in 2002. The rate of resistant tuberculosis among all DST results was 35.1% in 2000, 34.5% in 2001, and 33.8% in 2002. The number of MDR-TB patients (resistant against at least both isoniazid and rifampin) showed an increasing trend (14.5%) from 3,708 in 2000 to 4,245 in 2002. Conclusion : Approximately 4,000 MDR-TB cases are newly identified by DST annually and the number is showing an increasing trend. This study suggests that in order to cope with the current MDR-TB situation, the DST methods will need to be standardized and more aggressive measures will be required.

• Journal of Korean Society of Transportation
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• v.35 no.4
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• pp.261-277
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• 2017

This study defines influencing sections as the part of the road section where passing vehicles are traveling with the lower speed compared to speed limit due to speed humps. The influencing section was divided into 3 parts; influencing section before the speed hump, interval section, and influencing section after the speed hump. This analysis focused on the changes of each part depending on installation types, vehicle types, and daytime or nighttime. For the interval section, especially, the ratio of distance traveled with lower speed than speed limit to interval section is defined as effective influencing section ratio to be analyzed. Vehicle speed profiles were collected with a speed gun to extract influencing section lengths. The survival analysis was applied and estimated survival functions are compared with each other by several statistical tests. As a consequence, the average length of influencing section on the 50m sequential speed humps was 75.3% longer during the deceleration than that of isolated speed hump, and 18.9% during the acceleration. The effective influencing section ratio for the 30m and 50m sequential speed humps had a small difference of 81.0% and 76.0% while the absolute values of the section that passing speed were less than the speed limit were longer on 50m sequential speed humps, each being 24.3m and 38.0m. Using the log rank test, it was evident that sequential speed humps were more effective to increase the length of influencing sections compared to the isolated speed hump. Vehicle type was the strong factor for influencing section length on the isolated speed hump, but daytime or nighttime was not the effective one. This research result can be used for improving the efficiency selecting the installation point of speed humps for road safety and estimating the standard of the distance between sequential speed humps.

• The Korean Journal of Emergency Medical Services
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• v.5 no.1
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• pp.37-51
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• 2001

This study is aimed at examining the ethical values of EMT students. The results below are based on the revised questionnaires, which can be applicable to EMT from the original questionnaires developed by Lee(1990), with a sample of 124 students consisting of 63 first and 61 second year students, conducted November 2-8, 2001. Data were analyzed using SPSS in terms of means, standard deviations, t-test, ANOVA, Pearson's correlation coefficient. The results are as follows: 1. In the area of Human life, all subjects showed utilitarian disposition. All respondents perceived the item "When patients recognizing there is no hope for survival ask for euthanasia, it is ethically right to accommodate their opinions." as the most utilitarian item, whereas they perceived the item "When an hopeless patient is on cardiac arrest, it is ethically right to do CPR as the most deontoogical item. 2. In the area of patient relationship, all students of two groups took on deontoogical characteristics, but there were no statistically significant differences between two groups. All students perceived an item "EMT have to keep it secret if patients disclose their suicide intentions and ask for absolute secrecy" the most utilitarian item, whereas they perceived an item "Even though patients act and speak in a very rude manner, EMT people should do their best to provide care for patients." as the most deontoogical item. 3. In the area of task relationship, first year students perceived an item "Given time limitations, it is ethically right to give priority to the patients who can be rehabilitated over the patients who can't be fully recovered." as the most utilitarian item, whereas second year students perceived an item "Under no circumstances should any placebo be administered to patients." as the most utilitarian item. All students perceived an item "When EMT students see an unconscious person lying in the street, they have to give him/her emergency treatment." as the most deontoogical item. 4. In the area of coworker relationship, all students of two groups took on deontoogical disposition, but there were no significant differences between two groups. All students of two groups perceived an item "Suppose you are regarded as the person who would be promoted. However, you think that your coworker is more competent than you. In that case you should tell your supervisor about your coworker." as the most utilitarian item. First year students perceived an item, whereas second year students perceived an item "When you observe coworkers' misconduct at work, it is ethically right to ignore their misdeeds." as the most deontoogical item. 5. This study demonstrated that for the first year students, there is a correlational relationship between areas of human life and task relationship, and between areas of task relationship and coworker relationship, whereas for the second year students, there is a correlational relationship between areas of human life and task relationship. 6. In areas of human life and task relationship, there are significant differences according to attitudes toward EMT and attendance at ethics training sessions. In the area of coworker relationship, there are significant differences according to religion, attendance at ethics training sessions, and a code of ethics. Recommendations for future research, 1. Sample items to measure ethical values and the instrument tailored to the needs of EMT should be developed. 2. A longitudinal study to track ethical value changes according to the amount of work experience is needed. 3. A code of ethics and/or ethics training, which could apply in actual situations, should be implemented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5915-5922
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• 2013

In this study, with the aim of improving the performance of shale to allow for its use as coarse aggregate for concrete, we coated shale aggregates with water repellents and polymers and evaluated their physical properties such as density, water absorption rate, wear rate, and stability depending on the coating method. In addition, the effects of the performance improvement were evaluated by assessing the properties of fresh concrete produced by varying the shale substitution ratio, as well as the compressive strength, flexural strength, and freeze-thaw resistance according to curing ages. The test results revealed that the absolute dry densities of all coated aggregates satisfied the standard density for coarse aggregates for concrete(>$2.50g/cm^3$),and the absorption rate of the shale aggregate coated with water repellent decreased by about 50% compared with that of uncoated shale. The wear rate of the polymer-coated shale decreased by up to 13.0% compared with that of uncoated shale. All coated aggregates satisfied the stability standard for coarse aggregates for concrete(${\leq}12$). The water repellent-induced performance improvement decreased the shale aggregates' slump by about 20~30mm compared with that of the uncoated shale aggregates, and the air content of the repellent-coated shale aggregate increased by up to 0.9% compared with that of the uncoated shale aggregate. The compressive strength of the polymer-coated shale aggregates at a curing age of 28 days was RS(F) 95.7% and BS(F) 90.0%, and the flexural strength was RS(F) 98.0 % and BS(F) 92.0% of the corresponding values of concretes produced using plain aggregates. Furthermore, the concrete using polymer-coated shale aggregates showed a dynamic modulus of elasticity of RS(F) 91% and BS(F) 88% after 300 freeze-thaw cycles, thus demonstrating improved freeze-thaw durability.

• Korean Journal of Remote Sensing
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• v.36 no.5_3
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• pp.1037-1051
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• 2020

The accurate monitoring and forecasting of the intensity of tropical cyclones (TCs) are able to effectively reduce the overall costs of disaster management. In this study, we proposed a multi-task learning (MTL) based deep learning model for real-time TC intensity estimation and forecasting with the lead time of 6-12 hours following the event, based on the fusion of geostationary satellite images and numerical forecast model output. A total of 142 TCs which developed in the Northwest Pacific from 2011 to 2016 were used in this study. The Communications system, the Ocean and Meteorological Satellite (COMS) Meteorological Imager (MI) data were used to extract the images of typhoons, and the Climate Forecast System version 2 (CFSv2) provided by the National Center of Environmental Prediction (NCEP) was employed to extract air and ocean forecasting data. This study suggested two schemes with different input variables to the MTL models. Scheme 1 used only satellite-based input data while scheme 2 used both satellite images and numerical forecast modeling. As a result of real-time TC intensity estimation, Both schemes exhibited similar performance. For TC intensity forecasting with the lead time of 6 and 12 hours, scheme 2 improved the performance by 13% and 16%, respectively, in terms of the root mean squared error (RMSE) when compared to scheme 1. Relative root mean squared errors(rRMSE) for most intensity levels were lessthan 30%. The lower mean absolute error (MAE) and RMSE were found for the lower intensity levels of TCs. In the test results of the typhoon HALONG in 2014, scheme 1 tended to overestimate the intensity by about 20 kts at the early development stage. Scheme 2 slightly reduced the error, resulting in an overestimation by about 5 kts. The MTL models reduced the computational cost about 300% when compared to the single-tasking model, which suggested the feasibility of the rapid production of TC intensity forecasts.

• The Journal of the Korean Society for Microbiology
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• v.21 no.1
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• pp.133-144
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• 1986

This study was undertaken to assess the effect of ginseng administration on T lymphocyte induced local xenogenic graft-versus-host(GVM) reactions which were induced with thymocyte, spleen cell and lymph node cell of ICR mice. Mice received daily 10mg of 70% alcohol ginseng extract oral1y for 100days and control mice remained untreated for the same period of time. The cells from donor mice were injected intradermally into the closely shaven abdominal skin of Sprague-Dawley rats for GVH tests. The thymocyte from control(ginseng-untreated) mice showed a negative local GVH reaction, whereas thymocyte from experimental(ginseng-treated) mice showed a positive reaction with the rate of 17.4%. When spleen cells were injected, the incidence of positive local GVH reaction was 66.7% among ginseng-treated mice, as opposed to incidence of 45.5% of positive local GVH reaction among control mice. The incidence of positive local GVH reaction of the lymph node cells when injected into a recipient was 71.4% among ginseng-treated mice as compared with that of 18.9% among control mice. The relationship between spleen cell inoculum and intensity of the local GVH reaction was assessed in ginseng-untreated mice. The intensity of GVH reaction clearly appears to be dose related. In ginseng-treated mice, a minimum of $1{\times}10^7$ spleen cell was required for production of positive local GVH reaction with almost linear relationship up to an inoculum of $5{\times}10^8$ cells. In control mice, however, a minimum of $1{\times}10^8$ spleen cells was required for positive GVH reaction. These results strongly suggest that the ginseng administration augments significantly the local xenogenic GVH reaction which was used to assess T lymphocyte function and immunocompetence of mice and in addition to this, these results appear to support previous suggestions that the local GVH reaction consitutes a qualitative test of the functional activity of T lymphocytes. These results may be the first to induce local GVH reaction, employing rats as recipient and mice as donor. This study was also desingned to investigate some of the effects of ginseng extract on lymphocyte-macrophage interactions. This was accomplished by in vitro quantification of 1) migratory inhibitory factor(MIF) synthetic capacity of splenic lymphocytes in mice previously primed with ginseng 2) MIF responsiveness of mouse peritoneal macrophages or chicken peripheral leucocytes under the presence of ginseng extract 3) migration ability of chicken peripheral leucocytes by direct stimulation of ginseng extract or ginseng saponin and 4) immunosuppressive effects of immunosuppressants such as cyclophosphamide, cyclosporin A or dexamethasone. Mice divided equally into the ginseng and the saline groups, which received intraperitoneally daily 0.2ml of ginseng absolute alcohol-extract(5mg/ml) and same amount of saline for 15 days, respectively. The cellular immune responsiveness of these mice was assayed 15 days after ginseng pretreatment. Splenic lymphocytes of mice treated with ginseng, when stimulated with sensitized specific-antigen such as sheep red blood cells or toxoplasmin, or with polyclonal activator concanavalin A, produced significantly more MIF than those of control saline group. MIF responsiveness of normal mouse macrophages was significantly augmented when assayed under the presence of ginseng extract (1mg/ml). The migratory ability of normal chicken leucocytes in the absence of MIF was significantly decreased by the stimulation of ginseng extract alone. MIF response was significantly decreased by immunosuppressants and this impaired response was not restored by ginseng pretreatment. This study was additionally performed to evaluate the effect of ginseng on the expulsion of adult Trichinella spiralis in mice. ICR mice were infected experimentally by esophageal incubation of 300 T. spiralis infective muscle larvae prepared by acid-pepsin digestion of infected mice. and received oral administration of 70% alcohol ginseng extract(10mg/mouse/day) for the indicated days plus 4 days before infection. At various times after infection, the number of adult T. spiralis worms in small intestines was determined. Interestingly, ginseng-treatment was accompanied by accelerated expulson of T. spiralis. These results led to the conclusion that Panax ginseng caused some enhancing effect on GVH reaction, macrophage migration inhibition reaction and expulsion of T. spiralis. In addition these results suggested that the mechanisms responsible for this enhancement of ginseng may be chiefly or partially due to nonspecific stimulation of cell-mediated immune response.

• Journal of Food Hygiene and Safety
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• v.27 no.1
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• pp.55-62
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• 2012

This study is a survey of regulatees' perception on main contents and enforcement effect of the Act, the retailers at food stores within Green Food Zone, for the effective enforcement of "The Special Act on the Safety Management of Children's Dietary Life" legislated in 2008. Percentage, frequency analysis, and T-test are derived from the survey carried out to the 175 retailers at food stores within Green Food Zone, across the country except Jejudo, for the two months March and April of 2011. The survey results are as follows. Over 80% of the respondents are aware of comprehensive policy for child food safety and the enforcement of 'the Special Act' and considering the rate of satisfaction on food safety information provided by government, over 90% of the respondents, virtually most of them, are satisfied. The rate of awareness of Green Food Zone is about 80% and that of outstanding business for children is about 50%, showing little perception of it. The comparison of the survey result of 2011 with that of 2010, which have the same questions to the retailers within Green Food Zone, still indicates a need for enhancement of understanding on absolute standard, though it showed fairly better improvement in general. Several proposals are given in this study based on the survey results, which will contribute to the children food safety and health improvement in the end.