• Tuberculosis and Respiratory Diseases
• /
• v.47 no.2
• /
• pp.184-194
• /
• 1999

Backgrounds : The advent of penicillin has led to the marked reduction in the mortality from pneumococcal bacteremia, however, the mortality is still relatively high in this post-antibiotic era. Actually the prevalence of infection due to penicillin-resistant penumococci is increasing worldwide, and it is especially high in Korea due to irrelevant use of antibiotics. So, the high mortality of pneumococcal sepsis might be related to the emergence of penicillin-resistant strains, however, many other antibiotics, which eradicate pneumococci effectively, are available in these days. This has led us to suspect the role of penicillin-resistance in the high mortality rate. In this study, we evaluated the effect of penicillin resistance on the mortality of patients with penumococcal bacte remia. Methods: The study population consisted of 50 adult patients with penumococcal bacteremia who were admitted between Jan, 1990 and July, 1997. Medical records were analyzed retrospectively. Results: Most of the patients (96%) had underlying diseases. The most common local disease associated with pneumococcal bacteremia was pneumonia (42%), which was followed by spontaneous bacterial peritonitis (14%), cholangitis (10%), meningitis (8%), liver abscess (4%), pharyngotonsillitis (4%), sinusitis (2%) and cellulitis (2%). While the overall case-fatality rate in this study was 24%, it was higher when peumococcal bacteremia was associated with pneumonia (42%) or meningitis (50%). The rate of penicillin resistance was 40%, which was increased rapidly from 1991. The rate of penicillin resistance was significantly higher in patients with the history of recent antibiotics use and hospitalization within 3 months respectively. The clinical manifestations, that is, age, severity of underlying diseases, nosocomial infection, associated local diseases, and the presence of shock or acute renal failure were not statistically different between the patients with penicillin-resistant and -sensitive pneumococcal bacteremia. The mortality of patients infected with penicillin-resistant pneumococci was not statistically different from those with penicillin-sensitive pneumococcal bacteremia. Conclusion: Penicillin resistance is not associated with high mortality in adult patients with pneumococcal bacteremia. As the overall mortality is high, active penumococcal vaccination is recommended in patients with high risk of infection.

• KDI Journal of Economic Policy
• /
• v.13 no.2
• /
• pp.97-127
• /
• 1991

This paper investigates the roles and the limitations of the Korean antitrust agencies-the Office of Fair Trade (OFT) and the Fair Trade Commission (FTC) during the making of the major industrial policies of the 1980's. The Korean antitrust agencies played only a minimal role in three major industrial policy-making issues in the 1980's- the enactment of the Industrial Development Act (IDA), the Industrial Rationalization Measures according to the IDA, and the Industrial Readjustment Measures on Consolidation of Large Insolvent Enterprises based on the revised Tax Exemption and Reduction Control Act. As causes for this performance bias in the Korean antitrust system, this paper considers five factors according to the current literature on implementation failure: ambiguous and insufficient statutory provisions of the Monopoly Regulation and Fair Trade Act (MRFTA); lack of resources; biased attitudes and motivations of the staff of the OFT and the FTC; bureaucratic incapability; and widespread misunderstanding about the roles and functions of the antitrust system in Korea. Among these five factors, bureaucratic incompetence and lack of understanding in various policy implementation environments about the roles and functions of the antitrust system have been regarded as the most important ones. Most staff members did not have enough educational training during their school years to engage in antitrust and fair trade policy-making. Furthermore, the high rate of staff turnover due to a mandatory personnel transfer system has prohibited the accumulation of knowledge and skills required for pursuing complicated structural antitrust enforcement. The limited capability of the OFT has put the agency in a disadvantaged position in negotiating with other economic ministries. The OFT has not provided plausible counter-arguments based on sound economic theories against other economic ministries' intensive market interventions in the name of rationalization and readjustment of industries. If the staff members of antitrust agencies have lacked substantive understanding of the antitrust and fair trade policy, the rest of government agencies must have had serious problems in understanding the correst roles and functions of the antitrust system. The policy environment of the Korean antitrust system, including other economic ministries, the Deputy Prime Minister, and President Chun, have tended to conceptualize the OFT more as an agency aiming only at fair trade policy and less as an agency that should enforce structural monopoly regulation as well. Based on this assessment of the performance of the Korean antitrust system, this paper evaluate current reform proposals for the MRFT A. The inclusion of the regulation of conglomerate mergers and of business divestiture orders may be a desirable revision, giving the MRFTA more complete provisions. However, given deficient staff experties and the unfavorable policy environments, it would be too optimistic and naive to expect that the inclusion of these provisions alone could improve the performance of the Korean antitrust system. In its conclusion, this paper suggests several policy recommendations for the Korean antitrust system, which would secure the stable development and accumulation of antitrust expertise for its staff members and enough understanding and conformity from its environments about its antitrust goals and functions.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.25 no.3
• /
• pp.225-235
• /
• 2009

A common procedure of restoration of endodonticlly treated tooth with fiber-reinforced post is followed by core build-up after post cementation. However, this technique is complex and time-consuming. The aim of this study was to compare fracture strength of premolar, restored with various methods of core fabrications on fiber-reinforced posts and casting metal restoration. Forty five freshly extracted human mandibular premolars were obtained and devided into 5 groups acconding to the type of post and methods of core build-up. In Group A, D.T. $Light-post^{(R)}$ were cemented with $DUO-LINK^{TM}$ and then $LIGHT-CORE^{TM}$ was used for core restoration. In Group B, D.T. $Light-post^{(R)}$ and $DUO-LINK^{TM}$ were used for cementing in the postspace, and $DUO-LINK^{TM}$ was used again for core restoration. In Group C, $Light-post^{(R)}$ bonding and the core build-up were performed simultaneously by using $DUO-LINK^{TM}$. In Group D, $LuxaPost^{(R)}$ was bonded by using $LuxaCore^{(R)}-Dual$. Again, $LuxaCore^{(R)}-Dual$ was used for core restoration. In Group E, $LuxaPost^{(R)}$ bonding and the core build-up were performed simultaneously by using $LuxaCore^{(R)}-Dual$. Axial reduction was formed parallelly as possible and 45 degree bevel was made at buccal occlusal surface. Crowns were fabricated and cemented. Each tooth was embedded in self-curing acrylic resin to the level of 2mm below the CEJ. Specimens were fixed on universal testing machin such that the axis of the tooth was at 45 degree inclination to the horizontal plane, and compressive force was applied at a crosshead speed of 1mm/min until failure occurred. The mean fracture strength was the highest in group A followed by descending order in group B, D, E and C. However, there were no statistically significant differences between groups with regard to the fracture strength. The type of the post or build-up methods of the core does not seem to influence the fracture strength.

• The Journal of Korean Academy of Prosthodontics
• /
• v.51 no.3
• /
• pp.160-166
• /
• 2013

Purpose: The purpose of this study was to compare the fracture strength of traditional metal-ceramic crowns and full zirconia crowns according to the occlusal thickness. Materials and methods: A mandibular first molar resin tooth was prepared with 1.5 mm occlusal reduction, 1.0 mm rounded shoulder margin and $6^{\circ}$ taperness in the axial wall. Duplicating the resin tooth, 64 metal dies were fabricated. 48 full zirconia crowns were fabricated using Prettau zirconia blanks by ZIRKONZAHN CAD/CAM and classified into six groups according to the occlusal thickness (0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm). 16 metal-ceramic crowns were fabricated and classified into two groups according to the occlusal porcelain thickness (1.0 mm, 1.5 mm). All crowns were cemented on each metal die and mounted in a universal testing machine. The load was directed at the functional cusp of each specimen until catastrophic failure occurred. One-way ANOVA, Tukey multiple comparison test (${\alpha}=.05$) and t-test (${\alpha}=.05$) were used. Results: The results were as follows. 1. The test 1 group (646.48 N) showed the lowest fracture strength (P<.05), and the value of the test 2.3.4.5 groups (866.40 N, 978.82 N, 1196.82 N, 1222.41 N) increased as thickness increased, but no significant difference were found with the groups (P>.05). The value of test 6 group (1781.24 N) was significantly higher than those of the other groups (P<.05). 2. There were no significant differences of the fracture strength of metal ceramic crowns according to occlusal porcelain thickness 1.0 mm (2515.71 N) and 1.5 mm (3473.31 N) (P<.05). Conclusion: Full zirconia crown needs to be 1.0 mm or over in occlusal thickness for the posterior area to have higher fracture strength than maximum bite force.

• Tuberculosis and Respiratory Diseases
• /
• v.60 no.4
• /
• pp.419-425
• /
• 2006

Background : Severe community-acquired pneumonia (CAP) can develop into respiratory failure that requires mechanical ventilation (MV), which is associated with a higher rate of mortality. It was recently reported that a hydrocortisone infusion in severe CAP patients was associated with a significant reduction in the length of the hospital stay and mortality. This study evaluated efficacy of a hydrocortisone infusion for patients with severe CAP requiring MV. Methods : From February 2005 to July 2005, 13 patients (M : F = 10 : 3, mean age: $68.6{\pm}14.1years$), who were diagnosed with severe CAP and required MV, were enrolled in this study. Hydrocortisone was administered as an intravenous 200mg loading bolus, which was followed by an infusion at a rate of 10mg/hour for 7 days. The control group was comprised of patients with severe CAP requiring MV but in whom corticosteroid was not used before study period. The clinical and physiologic parameters on or by day 8 and the outcome in the hydrocortisone infusion group were compared with those in the control group. Results : 1) There was no significant difference in age, gender ratio, SAPS II, SOFA score, temperature, leukocyte count, PaO2/FiO2 (P/F) ratio, the number of patients with P/F ratio < 200, chest radiograph score, lung injury score and catecholamine-dependent septic shock between the hydrocortisone infusion group and control group at day 1. 2) At day 8, the proportion of patients with an improvement in the P/F ratio ${\geq}100$ and the chest radiograph score was significantly higher in the hydrocortisone infusion group than in the control group (61.5% vs. 15.4%, 76.9% vs. 23.1%, p< 0.05). However, there was no significant difference in the other clinical and physiologic parameters. 3). There was no significant difference in the duration of the MV, ICU stay, hospital stay and 10th and 30th day mortality between the two groups. Conclusion : Hydrocortisone infusion for patients with severe CAP requiring invasive mechanical ventilation may be effective in improving the level of oxygenation and the chest radiograph score.

• Journal of Energy Engineering
• /
• v.23 no.4
• /
• pp.31-40
• /
• 2014

The Korean government made the 2nd Energy Basic Plan to achieve 11% of new and renewable energies distribution rate until 2035 as a response to cope with international discussion about greenhouse gas emission reduction. Renewable energies include solar thermal, photovoltaic, bioenergy, wind power, small hydropower, geothermal energy, ocean energy, and waste energy. New energies contain fuel cells, coal gasification and liquefaction, and hydrogen. As public and private investment to enhance the distribution of new and renewable energies, it is necessary to clarify the economic effects of the new and renewable energies sector. To the end, this study attempts to apply an input-output analysis and analyze the economic effects of new and renewable energies sector using 2012 input-output table. Three topics are dealt with. First, production-inducing effect, value-added creation effect, and employment-inducing effect are quantified based on demand-driven model. Second, supply shortage effects are analyzed employing supply-driven model. Lastly, price pervasive effects are investigated applying Leontief price model. The results of this analysis are as follows. First, one won of production or investment in new and renewable energies sector induces 2.1776 won of production and 0.7080 won of value-added. Moreover, the employment-inducing effect of one billion won of production or investment in new and renewable energies sector is estimated to be 9.0337 persons. Second, production shortage cost from one won of supply failure in new and renewable energies sector is calculated to be 1.6314 won, which is not small. Third, the impact of the 10% increase in new and renewable energies rate on the general price level is computed to be 0.0123%, which is small. This information can be utilized in forecasting the economic effects of new and renewable energies sector.

• Journal of Intelligence and Information Systems
• /
• v.16 no.4
• /
• pp.99-112
• /
• 2010

Ensemble learning is a method for improving the performance of classification and prediction algorithms. It is a method for finding a highly accurateclassifier on the training set by constructing and combining an ensemble of weak classifiers, each of which needs only to be moderately accurate on the training set. Ensemble learning has received considerable attention from machine learning and artificial intelligence fields because of its remarkable performance improvement and flexible integration with the traditional learning algorithms such as decision tree (DT), neural networks (NN), and SVM, etc. In those researches, all of DT ensemble studies have demonstrated impressive improvements in the generalization behavior of DT, while NN and SVM ensemble studies have not shown remarkable performance as shown in DT ensembles. Recently, several works have reported that the performance of ensemble can be degraded where multiple classifiers of an ensemble are highly correlated with, and thereby result in multicollinearity problem, which leads to performance degradation of the ensemble. They have also proposed the differentiated learning strategies to cope with performance degradation problem. Hansen and Salamon (1990) insisted that it is necessary and sufficient for the performance enhancement of an ensemble that the ensemble should contain diverse classifiers. Breiman (1996) explored that ensemble learning can increase the performance of unstable learning algorithms, but does not show remarkable performance improvement on stable learning algorithms. Unstable learning algorithms such as decision tree learners are sensitive to the change of the training data, and thus small changes in the training data can yield large changes in the generated classifiers. Therefore, ensemble with unstable learning algorithms can guarantee some diversity among the classifiers. To the contrary, stable learning algorithms such as NN and SVM generate similar classifiers in spite of small changes of the training data, and thus the correlation among the resulting classifiers is very high. This high correlation results in multicollinearity problem, which leads to performance degradation of the ensemble. Kim,s work (2009) showedthe performance comparison in bankruptcy prediction on Korea firms using tradition prediction algorithms such as NN, DT, and SVM. It reports that stable learning algorithms such as NN and SVM have higher predictability than the unstable DT. Meanwhile, with respect to their ensemble learning, DT ensemble shows the more improved performance than NN and SVM ensemble. Further analysis with variance inflation factor (VIF) analysis empirically proves that performance degradation of ensemble is due to multicollinearity problem. It also proposes that optimization of ensemble is needed to cope with such a problem. This paper proposes a hybrid system for coverage optimization of NN ensemble (CO-NN) in order to improve the performance of NN ensemble. Coverage optimization is a technique of choosing a sub-ensemble from an original ensemble to guarantee the diversity of classifiers in coverage optimization process. CO-NN uses GA which has been widely used for various optimization problems to deal with the coverage optimization problem. The GA chromosomes for the coverage optimization are encoded into binary strings, each bit of which indicates individual classifier. The fitness function is defined as maximization of error reduction and a constraint of variance inflation factor (VIF), which is one of the generally used methods to measure multicollinearity, is added to insure the diversity of classifiers by removing high correlation among the classifiers. We use Microsoft Excel and the GAs software package called Evolver. Experiments on company failure prediction have shown that CO-NN is effectively applied in the stable performance enhancement of NNensembles through the choice of classifiers by considering the correlations of the ensemble. The classifiers which have the potential multicollinearity problem are removed by the coverage optimization process of CO-NN and thereby CO-NN has shown higher performance than a single NN classifier and NN ensemble at 1% significance level, and DT ensemble at 5% significance level. However, there remain further research issues. First, decision optimization process to find optimal combination function should be considered in further research. Secondly, various learning strategies to deal with data noise should be introduced in more advanced further researches in the future.

• The Journal of Korean Academy of Prosthodontics
• /
• v.60 no.2
• /
• pp.135-142
• /
• 2022

Purpose. This study aims to evaluate the combined effect of reduced thickness in different regions on the fracture resistance of monolithic zirconia crowns. Materials and methods. Seven nickel-chromium dies were generated from a 3D model of mandibular first molar using the digital scanner with the following geometries: 1.5 mm occlusal reduction, 1.0 mm deep chamfer. Based on the abutment model, Zirconia blocks (Luxen Zirconia) were selected to fabricate Sixty-three zirconia crowns with occlusal thicknesses of 0.3 mm, 0.5 mm, and 1.5 mm, and different axial thicknesses of 0.3 mm, 0.5 mm, and 1.0 mm. All crowns were cemented by resin cement. Next, the crowns were subjected to load-to-fracture test until fracture using an electronic universal testing machine. In addition, fracture patterns were observed with a scanning electron microscope (SEM). Two-way ANOVA and the Tuckey HSD test for post hoc analysis were used for statistical analysis (P < .05). Results. The mean values of fracture resistancerecorded was higher than the average biting force in the posterior region. The two-way ANOVA showed that the occlusal and axial thickness affected the fracture resistance significantly (P < .05). However, the effect of axial thickness on fracture resistance did not show a statistical difference when thicker than 0.5 mm. The observed failure modes were partial or complete fracture depending on the severity of crack propagation. Conclusion. Within the limitations of the present study, the CAD-CAM monolithic zirconia crown with extremely reduced thickness showed adequate fracture resistance to withstand occlusal load in molar regions. In addition, both occlusal and axial thickness affected the fracture resistance of the zirconia crown and showed different results as combined.

• Journal of Chest Surgery
• /
• v.37 no.10
• /
• pp.845-855
• /
• 2004

Background: No general consensus has been available regarding the necessity of postoperative radiation therapy (PORT) and its optimal techniques in the patients with chest wall invasion (pT3cw) and node negative (N0) non-small cell lung cancer (NSCLC). We did retrospective analyses on the pT3cwN0 NSCLC patients who received PORT because of presumed inadequate resection margin on surgical findings. And we compared them with the pT3cwN0 NSCLC patients who did not received PORT during the same period. Material and Method: From Aug. of 1994 till June of 2002, 22 pT3cwN0 NSCLC patients received PORT-PORT (＋) group- and 16 pT3cwN0 NSCLC patients had no PORT-PORT (-) group. The radiation target volume for PORT (＋) group was confined to the tumor bed plus the immediate adjacent tissue only, and no regional lymphatics were included. The prognostic factors for all patients were analyzed and survival rates, failure patterns were compared with two groups. Result: Age, tumor size, depth of chest wall invasion, postoperative mobidities were greater in PORT (-) group than PORT (＋) group. In PORT (-) group, four patients who were consulted for PORT did not receive the PORT because of self refusal (3 patients) and delay in the wound repair (1 patient). For all patients, overall survival (OS), disease-free survival (DFS), loco-regional recurrence-free survival (LRFS), and distant metastases-free survival (DMFS) rates at 5 years were 35.3%, 30.3%, 80.9%, 36.3%. In univariate and multivariate analysis, only PORT significantly affect the survival. The 5 year as rates were 43.3% in the PORT (＋) group and 25.0% in PORT (-) group (p=0.03). DFS, LRFS, DMFS rates were 36.9%, 84.9%, 43.1 % in PORT (＋) group and 18.8%, 79.4%, 21.9% in PORT(-) group respectively. Three patients in PORT (-) group died of intercurrent disease without the evidence of recurrence. Few suffered from acute and late radiation side effects, all of which were RTOG grade 2 or lower. Conclusion: The strategy of adding PORT to surgery to improve the probability not only of local control but also of survival could be justified, considering that local control was the most important component in the successful treatment of pT3cw NSCLC patients, especially when the resection margin was not adequate. Authors were successful in the marked reduction of the incidence as well as the severity of the acute and late side effects of PORT, without taking too high risk of the regional failures by eliminating the regional lymphatics from the radiation target volume.