• Clinical and Experimental Pediatrics
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• v.52 no.1
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• pp.68-74
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• 2009

Purpose : We assessed about the measles elimination in Korea according to analyzing national data on measles cases for 2002-2007. Methods : We estimated the effective reproduction number according to the proportion of imported cases and outbreak size. Results : Eleven cases, thirteen cases, six cases, six cases, 25 cases (60.0% were linked to 1 outbreak of 15 cases), and 180 cases (55.6% were linked 11 outbreaks of 2, 2, 2, 3, 3, 3, 5, 9, 9, 12, 50 cases) were reported in 2002, 2003, 2004, 2005, 2006 and 2007, respectively. In 2002-2007, R is 0.95 by imported case and 0.43 by outbreak sizes. In 2007, multiple chains of transmission occurred in hospital. Most of cases were below 4 ages and unvaccinated. We didn't find most of the infection source. Conclusion : We should prevent outbreak of susceptibility pocket like nosocomial infection, conduct reliable routine surveillance and epidemiological investigation to solve a problem of the measles elimination.

• Safety and Health at Work
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• v.2 no.2
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• pp.135-147
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• 2011

Objectives: The purpose of this study was to evaluate cancer risks in the Korean semiconductor industry. Methods: A retrospective cohort study was performed in eight semiconductor factories between 1998 and 2008. The number of subjects was 113,443 for mortality and 108,443 for incidence. Standardized mortality ratios (SMR) and standardized incidence ratios (SIR) were calculated. Results: The SMR of leukemia was 0.39 (95% Confidence Interval 0.08-1.14) in males (2 cases) and 1.37 (0.55-2.81) in females (7 cases). The SMR of non-Hodgkin's lymphoma (NHL) was 1.33 (0.43-3.09, 5 cases) in males and 2.5 (0.68-6.40, 4 cases) in females. The SIR of leukemia was 0.69 (0.30-1.37, 8 cases) in males and 1.28 (0.61-2.36, 10 cases) in females. The SIR of NHL in females was 2.31 (1.23-3.95, 13 cases) and that of thyroid cancer in males was 2.11 (1.49-2.89, 38 cases). The excess incidence of NHL was significant in female assembly operators [SIR=3.15 (1.02-7.36, 5 cases)], but not significant in fabrication workers. The SIR of NHL in the group working for 1-5 years was higher than the SIR of NHL for those working for more than five years. The excess incidence of male thyroid cancer was observed in both office and manufacturing workers. Conclusion: There was no significant increase of leukemia in the Korean semiconductor industry. However, the incidence of NHL in females and thyroid cancer in males were significantly increased even though there was no definite association between work and those diseases in subgroup analysis according to work duration. This result should be interpreted cautiously, because the majority of the cohort was young and the number of cases was small.

• Clinical and Experimental Reproductive Medicine
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• v.21 no.2
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• pp.221-226
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• 1994

Copper T 380A intrauterine devices were inserted to nine thousand and nine hundred twenty women by 51 KAVS-member physicians since January 1, 1993 through December 31, 1993. This study was undertaken for the clinical analysis on a total of 9,920 women wearing Copper T 380A to grasp the effectivness as well as the expulsion rate due to a various side effects. The following features were the results of the study: 1. During the twelve months period, from January 1993 to December 1993, the largest number of IUD insertion per one physician is 740 cases and the smallest number 60 cases, the mean 195 cases. 2. After insertion of Copper T 380A, a total of 117 cases were removed the IUD;81 cases(0.8%) were due to extensive bleeding and 36 cases(O.36%) were due to pain. The pregnancy failure rate represented comparatively lower rate, 0.08% (8 cases) and the expulsion rate was 0.06%(6 cases). 3. The removal rate of Copper T 380A was different by physicians. The highest removal rate for bleeding was 3.13% and 13 physicians(25.5%) did not experience any bleeding cases. 4. For the removal rate for pain, 30 physicians(58.8%) did not experience any removal of IUD due to pain while 21 physicians(41.2%) removed IUD due to pain: 17 physiciansC33.4 %) had 0.1-1.5% of removal rate and 4 physiciansC7.0%) had 1.6-2.1% of removal rate. 5. A total of 43 physicians(84.3 %) did not experience any pregnancy failure case while 8 (15.7%) physicians was experienced pregnancy failure rate. Four physicians(7.8%) had 0.1-0.5% of pregnancy failure rate and 4 physicians had 0.6-1.0% of pregnancy failure rate. 6. Expulsion rate showed comparatively lower, 0.06% in this study. A total of 45 physicians (88.2%) did not experience any expulsion cases while 6 physicians(11.7%) had expulsion rate with the highest expulsion rate of 2.0%.

• Journal of Chest Surgery
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• v.19 no.3
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• pp.399-406
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• 1986

131 cases of open heart surgery were performed in the Department of Thoracic and Cardiovascular Surgery, Kyungpook National University Hospital in 1985. There were 116 congenital cardiac anomaly and 15 acquired heart diseases. Out of 116 congenital cardiac anomaly, 73 cases of acyanotic group and 43 cases of cyanotic group were noted. In 73 cases of acyanotic group, 17 ASD, 52 VSD and 4 other acyanotic anomaly were noticed. In 43 cases of cyanotic group, 4 Trilogy of Fallot, 34 TOF, 1 Pentalogy, 3 DORV and 1 DCRV were included. Of the 15 acquired valvular heart disease cases, individual incidence was in mitral valve 10, double valve 3, and simple aortic valve 2 cases. Total number of valve replaced was 16, and 13 for mitral, 2 for aortic, and 1 for tricuspid in position, including 1 cases of double valve replacement. Overall operative mortality for 131 cases of open heart surgery was 4.5%, and the operative mortality was 5.5% in congenital acyanotic group, 2.3% in congenital cyanotic group, 0% in TOF group and 6.7% in acquired group.

• Journal of Chest Surgery
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• v.24 no.4
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• pp.404-420
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• 1991

Surgical treatment of congenital and acquired heart disease preceded the development of accurate techniques for diagnosis, heart lung machine and cardiopulmonary bypass, intraoperative myocardial protection, operative techniques and cardiac anesthesia. For 5 years from Sep. 1985 to Sep. 1990, six hundred cases of open heart surgeries [OHS] were performed in the department of Thoracic & Cardiovascular Surgery, Pusan Paik Hospital, College of Medicine, Inje University. The results were summarized as follows. 1. The annual number of OHS[cases per year] was above 100 since 1987, and the increasing rate of cases was 23.5% per year since 1986. 2. Among the total 600 cases, there were 470 cases of congenital heart diseases and 130 cases of acquired. Age range of the congenital patients was 8 months to 44 years with the mean age of 10 years, and acquired patients was 16 to 56 years with the mean age of 36 years. 3. Among the 470 congenital anomalies, there were 429 cases of acyanotic and 41 cyanotic patients. Totally, VSD was 286 cases[60.6%], ASD 103 cases[21.9%], TOF 35 cases [7.4%], PS 20 cases [4.1%], ECD 12 cases [2.0%], Ebstein`s anomaly 3 cases [0.6%], Valsalva sinus rupture 3 cases [0.6%] and others. The appropriate one stage radical operations were applied to the all congenital cases with the result of 2.6% immediate postoperative hospital mortality rate. 4. Among the 130 acquired cases, there were 122 cases of valvular heart diseases, 6 of heart tumors [5 myxoma, one malignant histiocytoma], one of LA thrombus and one of annuloaortic ectasia. Cardiac tumors and LA thrombus were removed through the atrial septal approach. Bentall procedure was adopted to the annuloaortic ectasia case. AVR, MVR and TVA [DeVega procedure] were applied to 120 valve diseases, and there were also one of OMC and one of MVA[Jerome-Kay procedure]. 5. Among the 120 valve replacement cases, there were 87 of single valve replacement cases [AVR: 8, MVR: 79], 11 of double valve replacement [AVR+MVR: 11], 12 of MVR+TVR and 10 of MVR+AVR+TVA. The total number of implanted prosthetic valves were 141. In MVR, 45 of St. Jude Medical valves, 63 of Carpentier-Edward valves and 4 of Ionescu-Shiley valves were used. In AVR, 18 of St. Jude Medical valves and 11 of Carpentier-Edward valves were used. in MVR, 29mm and 31mm sized valves were used mostly and In AVR, 23mm sized valves were used mostly. 6. Postoperatively many kinds of complications were occurred. Among them, wound problems [30 cases], low output syndrome [29 cases], arrhythmia [20 cases], pleural effusion and pneumothorax [13 cases] were occurred frequently. The postoperative immediate hospital mortality was 3.0% in total [congenital 2.6%, acquired 4.6%].

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.1
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• pp.1-13
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• 2006

In this paper we consider a design problem of a cyclic queueing network with two stages, each with a local buffer of limited capacity. Based on the theory of reversibility and product-form solution, we derive the throughput function of the network as a key performance measure to maximize. Two cases are considered. In case each stage consists of a single server, an optimal allocation policy of a given buffer capacity and work load between stages as well as the optimal number of customers is identified by exploiting the properties of the throughput function. In case each stage consists of multiple servers, the optimal policy developed for the single server case doesn't hold any more and an algorithm is developed to allocate with a small number of computations a given number of servers, buffer capacity as well as total work load and the total number of customers. The differences of the optimal policies between two cases and the implications of the results are also discussed. The results can be applied to support the design of certain manufacturing and computer/communication systems.

• Asia pacific journal of information systems
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• v.30 no.4
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• pp.785-807
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• 2020

The novel Coronavirus disease 2019 (COVID-19) is unprecedentedly changing the world since its outbreak in late 2019. Using the collected the data related to COVID-19 and the social media user data from a mobile application market research agency from January 25 to April 7, this study empirically examines the effect of the number of confirmed COVID-19 cases worldwide, the number news COVID-19, and the enforcement of social distancing measures on the daily active users (DAU) of two social media services - Twitter and Facebook - in South Korea. There are three important findings from the results of econometric analysis. First, the number of confirmed COVID-19 cases worldwide has a negative effect on the DAU of social media. Second, the number of COVID-19 news is negatively associated with the DAU of social media. Finally, the implementation of social distancing measures has no significant effect on the DAU of the social media. Theoretical implications and managerial guidelines are also discussed.

• Journal of the Korean Data and Information Science Society
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• v.21 no.2
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• pp.371-377
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• 2010

In this study, we propose two informal hypothesis tests which may be useful in determining the number of trees in a random forest for use in classification. The first test declares that a case is 'easy' if the hypothesis of the equality of probabilities of two most popular classes is rejected. The second test declares that a case is 'hard' if the hypothesis that the relative difference or the margin of victory between the probabilities of two most popular classes is greater than or equal to some small number, say 0.05, is rejected. We propose to continue generating trees until all (or all but a small fraction) of the training cases are declared easy or hard. The advantage of combining the second test along with the first test is that the number of trees required to stop becomes much smaller than the first test only, where all (or all but a small fraction) of the training cases should be declared easy.

• Korean Journal of Veterinary Research
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• v.16 no.2
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• pp.115-119
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• 1976

The survey was carried out to investigate the average number of days from parturition to conception to 349 calving cases out of Holstein cows in total 154 heads observed. The results were as follows: 1. The average number of days from parturition to conception was $97.41{\pm}8.22$ and it's similar during the period from primipara to 4th calving order, and irregular during on and after 5th. 2. The average number of days from parturition to conception in calving month was observed all through the year: the prolongation among on April and July, and the brief duration among on January and March. 3. In the cases under 50 and 150 days after delivery, the distribution showed 53.56% and 83.91%, respectively, and it's about 20% between 70 and 90 days after delivery.

• Journal of Chest Surgery
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• v.12 no.2
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• pp.113-118
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• 1979

The muscular variety of congenital ventricular septal defect [Type IV VSD] comprises from 2 to 18% of the total number of patients and has multiple defects. It is difficult to diagnose by usual angiographic study. Out of 116 cases of isolated ventricular septal defects repaired at this hospital in 20 years period from 1959 and to May 8, 1979, 2 cases had muscular defect which was treated through vertical right ventriculotomy without any problems. Single defect was found in both cases and in one case PDA was associated with Type IV VSD.