• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4762-4767
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• 2012

The AF track circuit that detecting train position and transmitting various train control data for DTG to the train on-board is composed of single operation system. If a failure occurs on this system, the driver should be operate the train by manually until the system is restored, because the system cannot control switch machines and signals by automatically. In this process the human error affects to the train delay, collision, derailment and critical safety accident. Therefore, this document has analyzed the effects that each failure mode influences on system and train, and quantified the failure valuation point and class. Basis on this quantified analysis result, MTBF increased and MTTR decreased and failure number also decreased by adopting the independent installation of power supply, the replacement of defected capacitors, the installation of resister cooling system and the improvement of maintenance methods. And the failure factors of AF track circuits were decreased by conducting the preventive maintenance which is a quantitative way of maintenance system by experience.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.2
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• pp.51-56
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• 2008

High quality power supplying of high voltage distribution lines electric railway system is the important function, high voltage distribution system is complicated witch is compose with distribution line, circuit break, protection facilities and so on. Among this components, role of substation is most important for elevation of reliability in electric power system. Therefore, the enhanced reliability considering the preventive inspection, repair work replacement is necessary. This paper proposes protection method in railway high voltage distribution lines. we model distribution system using PSCAD/EMTDC(Power System Computer Aided Design/Electro Magnetic Transients DC Analysis Program) and extract various fault data. In conclusion this methods can protection of ground fault.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.3
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• pp.1385-1391
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• 2016

Background: To investigate the prevalence of and factors associated with performance of annual mammography by women above 40 years of age. Materials and Methods: This cross-sectional retrospective study was conducted at an oncology reference service in Southern Brazil from October 2013 to October 2014 with 525 women aged 40 years or older. Results: The prevalence of annual mammography was 54.1%; annual mammographic screening was performed for women without private medical insurance, who were under hormone replacement therapy and who had used contraception in the past. An association was found between non-performance of breast clinical and self-examination and non-performance of mammographic screening. Conclusions: Use of mammography for breast cancer screening in the public health care setting proved to be accessible; nevertheless, the proportion of screened women was low, and they exhibited poor adherence to the basic measures of care recommended for breast assessment. Thus, control of breast cancer requires implementing actions targeting the population most vulnerable to non-adherence to screening in addition to continuously monitoring and assessing that population to reduce the prevalence of this disease.

• Preventive Nutrition and Food Science
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• v.21 no.2
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• pp.90-96
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• 2016

Snake tomato (Trichosanthes cucumerina) has been cultivated and used as a replacement for Lycopersicum esculentum in many Asian and African diets. Matured T. cucumerina fruits were harvested at different ripening stages and separated into coats and pulps for analyses to determine their suitability for use in culinary. They were analyzed for the nutritional composition and antioxidant potential using different biochemical assays [1,1-diphenyl-2-picrylhydrazyl, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activities, and ferric reducing antioxidant power] and antioxidative enzymes activities. The nutritional composition revealed that T. cucumerina contains over 80% water and is very rich in fiber, thus it can serve as a good natural laxative. The lycopene and ${\beta}$-carotene contents were especially high in the ripe pulp with values of $21.62{\pm}1.22$ and $3.96{\pm}0.14mg$/100 g, respectively. The ascorbic acid content was highest in the pulp of unripe fruit with a value of $56.58{\pm}1.08mg$/100 g and significantly (P<0.05) decreased as ripening progressed. The antioxidant potential of the fruits for the 3 assays showed that unripe pulp> ripe coat> ripe pulp> unripe coat. There were decreases in the antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, and glutathione reductase) activities, with the exception of catalase, as ripening progressed in the fruits. These decreased activities may lead to the softening of the fruit during ripening. Harnessing the antioxidative potential of T. cucumerina in culinary through consumption of the coats and pulps will alleviate food insecurity and help maintain good health among many dwellers in sub-Saharan Africa and Southeast Asia.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.3
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• pp.95-100
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• 2020

Machines and facilities are physically or chemically degenerated by continuous usage. One of the results of this degeneration is the process mean shift. The representative type of the degeneration is wear of tool or machine. According to the increasing wear level, non-conforming products cost and quality loss cost are increasing simultaneously. Therefore a periodic preventive resetting the process is necessary. The total cost consists of three items: adjustment cost (or replacement cost), non-conforming cost due to product out of upper or lower limit specification, and quality loss cost due to difference from the process target value and the product characteristic value among the conforming products. In this case, the problem of determining the adjustment period or wear limit that minimizes the total cost is called the 'process mean shift' problem. It is assumed that both specifications are set and the wear level can be observed directly. In this study, we propose a new model integrating the quality loss cost, process variance, and production volume, which has been conducted in different fields in previous studies. In particular, for the change in production volume according to the increasing in wear level, we propose a generalized production quantity function g(w). This function can be applied to most processes and we fitted the g(w) to the model. The objective equation of this model is the total cost per unit wear, and the determining variables are the wear limit and initial process setting position that minimize the objective equation.

• Journal of the Korea Concrete Institute
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• v.17 no.1 s.85
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• pp.129-137
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• 2005

In Korea, due to the insufficiency of natural aggregates and increasing needs of crushed stones, it is necessary to examine the alkali-silica reaction of the crushed stones. The reaction produces an alkali-silica reaction gel which can imbibe pore solution and swell to generate cracks that are visible In affected concrete. In general, crushed stones are tested by petrograptuc examination, chemical method and mortar-bar method, but the most reliable method Is mortar-bar test. This study tested alkali-silica reactivity of crushed stones of various rock types using ASTM C 227 and C 1260, and compared the results of two test methods. This study also analyzed effects of particle size and grading of reactive aggregate on alkali-silica reaction expansion of mortar-bar. The effectiveness of mineral admixtures to reduce detrimental expansion caused by alkali-silica reaction was investigated through the ASTM C 1260 method. The mineral admixtures used were nv ash, silica fume, metakaolin and ground granulated blast furnace slag. The replacement ratios of 0, 5, 10, 15, 25 and $35\%$ were commonly applied for all the mineral admixtures and the replacement ratios of 45 and $55\%$ were additional applied for the admixtures that could maintain workability. The results indicate that replacement ratios of $25\%$ for ay ash, $10\%$ for silica fume, $25\%$ for metakaolin or $35\%$ for ground granulated blast furnace slag were most effective to reduce alkali-silica reaction expansion under the experimental conditions.

• Preventive Nutrition and Food Science
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• v.19 no.2
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• pp.115-123
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• 2014

In the current study, wheat flour was mixed with high quality cassava flour (HQCF) in several ratios: 90:10, 80:20, 70:30, and 60:40, and used to prepare 10%, 20%, 30%, and 40% National Root Crops Research Institute (NRCRI) cassava bread, respectively. 100% wheat bread was prepared as a control (100% wheat bread). Five bread samples were prepared per group. Antioxidant assays [i.e., 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging assay, reducing power assay] revealed that the bread samples had considerable antioxidant capacities. Substitution of wheat flour with HQCF at various concentrations resulted in dose dependent decreases in the mineral and protein contents of the resulting bread samples. The crude fiber content of the bread samples was minimal, while the carbohydrate content of the bread samples ranged from 43.86% to 48.64%. A 20% substitution of wheat flour with HQCF yielded bread samples with a general acceptability that was comparable to that of 100% wheat bread. The mean bacteria counts of the bread samples ranged from $2.0{\times}10^3CFU/mL$ to $1.4{\times}10^4CFU/mL$, while the fungal counts ranged from 0 CFU/mL to $3{\times}10^3CFU/mL$. There was a positive correlation between the DPPH antioxidant activities and the reducing powers of the bread samples ($R^2=0.871$) and a positive correlation between the DPPH antioxidant activities and the flavonoid contents of the bread samples ($R^2=0.487$). The higher microbial load of the NRCRI cassava bread samples indicates that these bread samples may have a shorter shelf life than the 100% wheat bread. The significant positive correlation between total flavonoid content and reducing power ($R^2=0.750$) suggests that the flavonoids present in the lipophilic fractions of the bread samples could be responsible for the reductive capacities of the bread samples.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.667-674
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• 2022

In this study, the correlation between the damage type and operating conditions of the sleepers was analyzed based on the design data and visual inspection results for the concrete sleepers of the sleeper floating track (STEDEF) that have been in operation for more than 20 years. It appeared in the form of cracks, breakages, and breaks in the concrete at the center and tie bar contact and buried areas. As a result of the numerical analysis, it was analyzed that the change in the left and right spring stiffness of the sleeper resilience pad increases the maximum stress, tensile stress, compressive stress, and displacement of the concrete sleeper, and stress concentration in the concrete at the tie bar contact area. It was proved analytically that the sleeper resilience pad can affect the damage of the concrete sleeper. Therefore, damage of concrete sleepers in the sleeper floating track in urban transit could be caused by changes in spring stiffness of sleeper resilience pads. It was reviewed that preventive maintenance such as improvement and timely replacement of sleeper resilience pads was necessary.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.7
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• pp.475-484
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• 2018

The propulsion control device of an electric railway vehicle is a key main component corresponding to an engine of an automobile, and a device for controlling this is a device called a GDU (Gate Drive Unit). Also, when the frequency of failure of the propulsion control system was analyzed, the nonconformity ratio of GDU was the highest. GDU was not able to access core technologies due to the introduction of foreign products, and there were general problems with overall maintenance activities due to discontinuation of GDU of the manufacturer. The GDU has reached the end of its life with 23 to 14 years of long-term use.In order to solve these problems, this study was designed to identify the proper life span by analyzing compatible GDU's acquisition and failure, and to improve the existing system of maintenance focusing on health inspection. Maintenance of the components with a short life span compared to the entire service life is essential. Most foreign parts introduced at the beginning of the construction are not replaced due to technical problems or long-term operation. However, due to the characteristics of railway vehicles with a long life span of more than 25 years, it is necessary to maintain them for a long period of time. The study should be more concrete and empirical. The replacement type GDU of capacitors was able to easily measure the life of the capacitance by removing the capacitor modules, measure the life span of each unit test, and accurately perform preventive maintenance of the capacitor.

• Journal of Korean Neurosurgical Society
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• v.66 no.6
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• pp.716-725
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• 2023

Objective : Anterior cervical spine surgery (ACSS) is a common surgical procedure used to treat cervical spinal degenerative diseases. One of the complications associated with ACSS is prevertebral soft tissue swelling (PSTS), which can result in airway obstruction, dysphagia, and other adverse outcomes. This study aims to investigate the correlation between various cervical sagittal parameters and PSTS following single-level ACSS, as well as to identify independent risk factors for PSTS. Methods : A retrospective study conducted at a single institution. The study population included all patients who underwent single-level ACSS between January 2014 and December 2022. Patients with a history of cervical spine surgery or trauma were excluded from the study. The presence and severity of PSTS was assessed by reviewing pre- and postoperative imaging studies. The potential risk factors for PSTS that were examined include patient age, sex, body mass index, tobacco use, comorbidities, serum albumin levels, operative time, implant type, implanted level, and various cervical spine sagittal parameters. Multivariate linear regression analysis was performed to identify the independent risk factors for PSTS. Results : A total of 62 consecutive patients who underwent single-level ACSS over a 8-year period at a single institution were enrolled in this study. Only preoperative segmental angle showed positive correlation with PSTS among various cervical spine sagittal parameters (r=0.36, p=0.005). Artificial disc replacement showed a negative correlation with PSTS (β=-0.38, p=0.002), whereas the use of demineralized bone matrix (DBM) had a positive impact on PSTS (β=0.33, p=0.009). We found that male sex, lower preoperative serum albumin, and implantation of upper cervical level (above C5) were independent predictors for PSTS after single-level ACSS (β=1.21; 95% confidence interval [CI], 0.27 to 2.15; p=0.012; β=-1.63; 95% CI, -2.91 to -0.34; p=0.014; β=1.44; 95% CI, 0.38 to 2.49; p=0.008, respectively). Conclusion : Our study identified male sex, lower preoperative serum albumin levels, and upper cervical level involvement as independent risk factors for PSTS after single-level ACSS. These findings can help clinicians monitor high-risk patients and take preventive measures to reduce complications. Further research with larger sample sizes and prospective designs is needed to validate these findings.