• The Transactions of the Korea Information Processing Society
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• v.3 no.7
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• pp.1917-1923
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• 1996

The reliability of the multiple-disk system is degraded as the number of disks are increased. In this paper, we find the reliability, in terms of MTTF (Mean Time To Failure)of the single-disk-failure-tolerant disk systems in which the distributions of repair times of failed disk are heterogeneous and general. Also, we derive thresholds of the design parameters such as the mean of life time and repair time, and we consider the cost minimization problem in the special cases under a linear cost structure and constraints to the life of the disk system.

• Journal of the Korean Data and Information Science Society
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• v.27 no.3
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• pp.711-724
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• 2016

Under variable complex operating environment, various factors can affect the lifetimes of systems. In this research, we study bivariate reliability models having multiple dynamic competing risks. As competing risks, in addition to the natural failure, we consider the increased stress caused by the failure of one component, external shocks, and the level of stress of the working environment at the same time. Considering two reliability models which take into account all of these competing risks, we derive bivariate life distributions. Furthermore, we compare these two models and also compare the distributions of maximum and minimum statistics in the two models.

• Tuberculosis and Respiratory Diseases
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• v.79 no.3
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• pp.158-164
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• 2016

Background: One to three percent of cases of acute tuberculosis (TB) require monitoring in the intensive care unit (ICU). The purpose of this study is to establish and determine the mortality rate and discuss the causes of high mortality in these cases, and to evaluate the clinical and laboratory findings of TB patients admitted to the pulmonary ICU. Methods: The data of patients admitted to the ICU of Yedikule Chest Diseases and Chest Surgery Education and Research Hospital due to active TB were retrospectively evaluated. Demographic characteristics, medical history, and clinical and laboratory findings were evaluated. Results: Thirty-five TB patients (27 males) with a median age of 47 years were included, of whom 20 died within 30 days (57%). The Acute Physiology and Chronic Health Evaluation II (APACHE II) and Sequential Organ Failure Assessment (SOFA) scores were significantly higher, and albumin and $PaO_2/FIO_2$ levels were significantly lower, and shock, multiple organ failure, the need for invasive mechanical ventilation and drug resistance were more common in the patients who died. The mortality risk was 7.58 times higher in the patients requiring invasive mechanical ventilation. The SOFA score alone was a significant risk factor affecting survival. Conclusion: The survival rate is low in cases of tuberculosis treated in an ICU. The predictors of mortality include the requirement of invasive mechanical ventilation and multiple organ failure. Another factor specific to TB patients is the presence of drug resistance, which should be taken seriously in countries where there is a high incidence of the disease. Finding new variables that can be established with new prospective studies may help to decrease the high mortality rate.

• Clinical and Experimental Pediatrics
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• v.59 no.2
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• pp.59-64
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• 2016

Purpose: Infantile Marfan syndrome (MFS) is a rare congenital inheritable connective tissue disorder with poor prognosis. This study aimed to evaluate the cardiovascular manifestations and overall prognosis of infantile MFS diagnosed in a tertiary referral center in Korea. Methods: Eight patients diagnosed with infantile MFS between 2004 and 2014 were retrospectively evaluated. Results: Their median age at the time of diagnosis was 2.5 months (range, 0-20 months). The median follow-up period was 25.5 months (range, 0-94 months). The median length at birth was 50.0 cm (range, 48-53 cm); however, height became more prominent over time, and the patients were taller than the 97th percentile at the time of the study. None of the patients had any relevant family history. Four of the 5 patients who underwent DNA sequencing had a fibrillin 1 gene mutation. All the patients with echocardiographic data of the aortic root had a z score of >2. All had mitral and tricuspid valve prolapse, and various degrees of mitral and tricuspid regurgitation. Five patients underwent open-heart surgery, including mitral valve replacement, of whom two required multiple operations. The median age at mitral valve replacement was 28.5 months (range, 5-69 months). Seven patients showed congestive heart failure before surgery or during follow-up, and required multiple anti-heart failure medications. Four patients died of heart failure at a median age of 12 months. Conclusion: The prognosis of infantile MFS is poor; thus, early diagnosis and timely cautious treatment are essential to prevent further morbidity and mortality.

• Magazine of the Korea Concrete Institute
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• v.9 no.2
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• pp.133-144
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• 1997

Concrete plasticity models fol the analysis of reinforced concrete members in plane stress are studied. The proposed plasticity model for reinforced concrete provides a unified approach combining plasticity theory and damage models. It addresses strength mhancement under rnultiaxial compression. and tensile cracking damage. The model uses multiple failure criteria for compressive crushing and tensile cracking. For tensile cracking behavior. rotating-crack and fixed-crack plasticity models are compared. As crushing failure criterion, the Drucker-Prager and the von Mises models are used for comparison. The model uses now and existing damnge models fbr tension softening, tension stiffening. and compression softening dup to tensilt. cracking. Finite element analyses using the unified method are compatxd with existing rxpcrimcntal r.esults. To vei.ify the proposcd crushing and cracking plasticity models, the experiments have load capacities govc11.nc.d either by compressive crushing of'concrete or by yi~lding of' reinforcing steel.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.65-75
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• 2021

This study explores multiple variables of an OTT service for discovering hidden relationship between rating and the other variables of each successful and failed content, respectively. In order to extract key variables that are strongly correlated to the rating across the contents, this work analyzes 170 Netflix original dramas and 419 movies. These contents are classified as success and failure by using the rating site IMDb, respectively. The correlation between the contents, which are classified via rating, and variables such as violence, lewdness and running time are analyzed to determine whether a certain variable appears or not in each successful and failure content. This study employs a regression analysis to discover correlations across the variables as a main analysis method. Since the correlation between independent variables should be low, check multicollinearity and select the variable. Cook's distance is used to detect and remove outliers. To improve the accuracy of the model, a variable selection based on AIC(Akaike Information Criterion) is performed. Finally, the basic assumptions of regression analysis are identified by residual diagnosis and Dubin Watson test. According to the whole analysis process, it is concluded that the more director awards exist and the less immatatable tend to be successful in movies. On the contrary, lower fear tend to be failure in movies. In case of dramas, there are close correlations between failure dramas and lower violence, higher fear, higher drugs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.156-161
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• 2020

In an environment that operates multiple UAVs, the use of a decentralized task allocation algorithm has more robustness from a single failure of UAV on the mission because there is no central command center. In addition, UAVs have situational awareness and redistribute tasks among themselves, which can expand the mission range. The use of multiple UAVs in a mission has increased as the agent hardware has decreased in size and cost. The decentralized mission-planning algorithm has the advantages of a larger mission range and robustness to a single failure during the mission. This paper extended the type of mission the uses CBBA, which is the most well-known decentralized task allocation algorithm, to the point mission and en-route mission. This will describe the real mission situation that has the purpose of surveillance. A Monte-Carlo simulation was conducted in the case of multiple agents in the task-rich environment, and the global rewards of each case were compared.

• Clinical and Experimental Pediatrics
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• v.48 no.9
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• pp.1004-1008
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• 2005

Hemangiomas are the most common benign tumors of infancy. Fifteen to 30% of these patients have multiple hemangiomas. Diffuse neonatal hemangiomatosis (DNH) is a disease that often has a fatal outcome if left untreated, and is characterized by multiple cutaneous and visceral hemangiomas. Corticosteroids are the commonly accepted first line treatment, but if no effect is seen, further treatment is required such as interferon, surgical excision, embolization and radiotherapy. Interferon is effective, but the neurologic sequela including spastic diplegia can be a complication. We experienced a case of DHN in a neonate. In this case, the baby presented with multiple cutaneous and visceral hemangiomas with Kasabach-Merritt syndrome (KMS) that included thrombocytopenia and consumptive coagulophthy. The baby was successfully treated with vincristine after the failure of steroid therapy.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.1
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• pp.31-38
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• 2012

Next generation cellular applications and smart phone usage generate very heavy wireless data traffic. It becomes ineluctable for mobile network operators to have multiple core network entities such as Serving Gateway and Packet Data Network Gateway in 4G-LTE to share this high traffic generated. A typical configuration consists of multiple serving gateways behind a load-balancer which would determine which serving gateway would service a end-users'request. Such hardware is expensive, has a rigid policy set, and is a single point of failure. Another perspective of today's increasingly high data traffic is that besides it is being widely accepted that the high bandwidth L TE provides is creating bottlenecks for service providers by the increasing user bandwidth demands without creating any corresponding revenue improvements, a hidden problem that is also passively advancing on the newly emerging 4G-LTE that may need more immediate attention is the network signaling traffic, also known as the control-plane traffic that is generated by the applications developed for smartphones and tablets. With this as starting point, in this paper, we propose a solution, by a new approach considering OpenFlow switch connected to a controller, which gains flexibility in policy, costs less, and has the potential to be more robust to failure with future generations of switches. This also solves the problem of scaling the control-plane traffic that is imperative to preserve revenue and ensure customer satisfaction. Thus, with the proposed architecture with OpenFlow, mobile network operators could manipulate the traffic generated by the control-plane signaling separated from the data-plane, besides also reducing the cost in installing multiple core-network entities.

• The Journal of Advanced Prosthodontics
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• v.12 no.4
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• pp.197-203
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• 2020

PURPOSE. The aim of this study was to evaluate the effect of multiple firings on the bond strength between yttriatetragonal zirconia polycrystals (Y-TZP) and 2 types of resin cements. MATERIALS AND METHODS. Sixty 3Y-TZP specimens (LAVA Frame Multi) were divided into 3 groups depending on the following firing procedures: (1) 2-firing cycles, (2) 5-firing cycles, (3) 10-firing cycles. Two samples from each group were investigated by using SEM to determine the morphological changes. All specimens were treated with 125 ㎛ airborne-particle abrasion and the surface roughness of each specimen was measured. The specimens from each firing group were then further divided into 2 subgroups (n = 9) to apply 2 types of resin cement (MDP-free resin cement: RelyX Unicem-RU, and MDP containing resin cement: Panavia F 2.0-PA). The shear bond strength (SBS) test was performed and failure types of all the debonded specimens were classified by using a stereomicroscope as adhesive, cohesive, and mixed. The statistical analysis of surface roughness and SBS data were performed by using 1-way ANOVA and 2-way ANOVA followed by Tukey-HSD tests (α=.05). Failure modes were calculated as a percentage for each group. RESULTS. The bond strength of RU and PA to the specimens obtained with 2 firings were not statistically different from each other (P=.1). However, the SBS values of PA were found to be significantly higher than RU for the specimens obtained with 5 and 10 firing cycles (P=.001 and P=.02, respectively). Surface roughness analysis revealed no statistical difference between groups (P=.2). The SEM analysis of samples fired 5- and 10- times showed irregularities and boundary loss in zirconia grains, and empty spaces between zirconia grains. CONCLUSION. The bond strength of PA cement was higher than that of RU to the zirconia subjected to repeated firings (5 and 10 firing cycles). When zirconia is subjected to multiple firings, using MDP-containing resin cement can be recommended.