• Journal of Life Science
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• v.10 no.5
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• pp.484-489
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• 2000

Enterovirues may cause gastrointestinal symptoms, cold, and fever, mainly in young children. They are also recognized as important agents in acute infections of the central nervous system such as meningitis and encephalitis, and in subacute and chronic infections of the cardiovascular system such as pericarditis, myocarditis and cardiomyopathy. They also can lead to postviral fatigue syndrome. For the detection of enteroviruses from the environmental samples, the combined cell culture-polymerase chain reaction (CC-PCR) technique was employed. In contrast to EPA standard method which mainly depends on the cell culture, it involved the use of cell culture, followed by PCR to improve the sensitivity and the accuracy of the test. According to the results of survey, from 1999 to 2000, for the presence of enteroviruses in the surface water samples from Nak-dong river, four out of twelve samples were positive for viruses. The titer of viruses in the surface water was ranged from 25 to 250 MPN. All of the viruses isolated were poliovirus type I with 98% nucleotide sequence homology. The result also clearly suggests the seasonal difference in the distribution of the waterborne enteroviruses in surface water because most of the viruses were mainly detected from the summer through the early autumn.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.4
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• pp.72-78
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• 2010

Textile machinery affects various industry, such as sport leisure industry, metal and chemistry material, electric electron, mechanical energy, packing and printing industry. In case of design of textile machine, the very important fact is absorbing the minute vibration induced by spinning thread and insert which is the part of spindle plays a role of reduction of impact caused by oscillation of thread bobbin. Therefore, Optimal design was executed by design of experiments and kriging optimal design methods to prevent fracture of spindle insert under the fatigue condition and deduced the best value of design parameter to improve the stability of the products. The highest sensitivity is showed at the design parameter A and D. As the spiral number of insert is increase, tension force applied its edge is distributed at whole model and the stress concentration is reduced.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2654-2663
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• 2000

Steam turbine rotors are the most critical and highly stressed components of a steam power plant; therefore, the life expectancy of the turbine rotor is an important consideration for the safety of a steam power plant. The objective of this paper is to develop a life estimation program for turbine rotors for all possible operating conditions. For this purpose, finite element analysis was carried out for four normal operating modes (cold, warm, hot and very hot starts) using ABAQUS codes. The results are made into databases to evaluate the life expenditure for an actual operating condition. For any other possible abnormal operating condition, the operating data are transmitted to the server (workstation) through a network to carry out finite element analysis. Damage estimation is carried out by transmitting the finite element analysis results to the personal computer, and then the life expectancy is calculated.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.7
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• pp.611-617
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• 2015

In the development of a vibration-based condition monitoring system in gearbox, one of the most important research topics is a quantitative analysis and test of the effect of gear damage on vibration of gearbox. This paper presents the evaluation result of vibration condition indicator according to the gear tooth damage through the vibration test of gearbox. The dynamic load test was performed with high speed railway (KTX)'s gearbox. The vibration of gearbox was measured according to a rotational speed change with the common gear fault modes, such as pitting and tooth breakage. The characteristics and the possibility of applying of vibration condition indicator on condition monitoring system were analyzed. As a result, the value of most condition indicator is gradually increased with the severity of gear faults. The NA6 indicator shows a low variation with the rotational speed change and high sensitivity in accordance with the gear fault.

• Journal of Auto-vehicle Safety Association
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• v.12 no.1
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• pp.52-61
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• 2020

In recent years, the increasing interest in health-care requires the industrial products to be well-designed ergonomically. In the commercial vehicle industry, several researchers have demonstrated the driver's posture has great effect on the orthopedic desease such as fatigue, back pain, scoliosis, and so on. However, the existing sensor systems developed for measuring the driver posture in real time have suffered from inaccuracy and low reliability issues. Here, we suggest our smart vehicle seat system capable of real-time driver posture monitoring by using the air bag sensor package with high sensitivity and reliability. The ergonomic numerical model which can evaluate a driver's posture has been developed on the basis of the human body segmentation method followed by simulation-based validation. Our experimental analysis of obtained pressure distribution of a vehicle seat under the different driver's postures revealed our smart vehicle system successfully achieved the driver's real-time posture data in great agreement with our numerical model.

• The Journal of Advanced Prosthodontics
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• v.14 no.3
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• pp.182-202
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• 2022

PURPOSE. The aim of this study is to summarize various biomechanical aspects in evaluating the long-term stability of dental implants based on finite element method (FEM). MATERIALS AND METHODS. A comprehensive search was performed among published studies over the last 20 years in three databases; PubMed, Scopus, and Google Scholar. The studies are arranged in a comparative table based on their publication date. Also, the variety of modeling is shown in the form of graphs and tables. Various aspects of the studies conducted were discussed here. RESULTS. By reviewing the titles and abstracts, 9 main categories were extracted and discussed as follows: implant materials, the focus of the study on bone or implant as well as the interface area, type of loading, element shape, parts of the model, boundary conditions, failure criteria, statistical analysis, and experimental tests performed to validate the results. It was found that most of the studied articles contain a model of the jaw bone (cortical and cancellous bone). The material properties were generally derived from the literature. Approximately 43% of the studies attempted to examine the implant and surrounding bone simultaneously. Almost 42% of the studies performed experimental tests to validate the modeling. CONCLUSION. Based on the results of the studies reviewed, there is no "optimal" design guideline, but more reliable design of implant is possible. This review study can be a starting point for more detailed investigations of dental implant longevity.

• Journal of the Korean Society of Safety
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• v.37 no.1
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• pp.55-63
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• 2022

The correlation between the Military Service Adaptation Test and the Biometric Index is studied herein with the aim of preventing military safety accidents. The subjects were 36 soldiers under the age of 25 years. Based on the results of the service adaptation test, the soldiers who did not adapt to the service were distinguished. First, there was a significant difference in brain stress among the brain wave indicators of the general group and the group of interest. Second, the higher the left and right brain imbalance index among the brain wave indicators, the higher was the level of empathy shown by the subjects. Third, among the pulse indicators, the subjects with high cumulative fatigue levels were found to have high levels of emotion (anxiety, depression, physicalization) and relationship isolation (indifference, sensitivity). Based on these results, the implications of this study and suggestions for future research are discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6C
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• pp.251-258
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• 2011

Steel pipe piles have been used as various deep foundation materials for a long time. Recent increase in steel material cost has made engineers reluctant in using it even with its good quality and ease of construction. Therefore when constructing with steel pipe pile, the decision to reuse the excessive pile length that is cut off from the designed pile head elevation after pile driving can be cost saving. This has caused many constructors to reuse the pile leftovers with new piles, but the absence of quantitative structural capacity behaviors of steel pipe pile after pile driving or appropriate countermeasures and standards in reusing steel pipe pile has resulted in wrong applications, pile structural integrity problems, inappropriate limitation of reusable pile length, etc. The structural performance analysis between a new pile and a pile that has undergone working state and ultimate state stress level during pile driving was performed in this research by means of comparing the results between the dynamic pile load test, tensile load test, charpy energy test and fatigue test for high strength steel of $440N/mm^2$ yield strength. Test results show that under working load conditions the yield strength variation is less than 2% and for ultimate load conditions the variation is less than 5% for maximum total blow count of 3000. The results have been statistically analyzed to check the sensitivity of each factors involved. From the test results, reusability of steel pipe pile lies not in the main pipe yield strength deviation but in the reduction of absorb energy, strength changes and quality control at the welded section, shape deformation and local buckling during pile driving.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.1
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• pp.71-77
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• 2023

With the continuous industrial development, not only natural resource depletion, waste generation, but also various weather conditions are becoming more frequent. Efforts are continuing to recycle industrial by-products to overcome the climate crisis and save resources. Slag is a representative by-product generated in the steel industry, and it is characterized by improving rutting resistance and moisture sensitivity by increasing strength and reducing deformation when used as a material for asphalt concrete. On the other hand, slag has expansion properties so it is used as a relatively low-value-added material such as embankment and refilling materials. In order to expand the application of slag, an experiment was conducted to evaluate the crack resistance of slag asphalt concrete pavement. As a result of the indirect tensile strength test, it was found that the asphalt mixture using slag aggregate showed a value 1.13 times higher than that of the general HMA with the same particle size, and the toughness was 1.17 units, improving crack resistance. In addition, it was found that the failure number of the 4-point beam fatigue experiment and the slag asphalt mixture was 20,409, which was more than doubled compared to the general HMA. Furthermore, Overlay Test showed a tensile load residual rate of 4 times or more, improving crack resistance to repeated fatigue. Accordingly, the use of slag aggregate will likely have various advantages in improving the performance of asphalt concrete pavement.

• Korean Journal of Psychosomatic Medicine
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• v.11 no.1
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• pp.15-24
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• 2003

Objectives: The object of this study was to compare perceived stress and quality of life among patients with HIV infection, patients with pulmonary tuberculosis and normal controls. Methods: Stress response inventory(SRI) and Symptom checklist 90-Revised(SCL-90-R) were used to measure perceived stress responses and psychopathology. Smithklein Beecham quality of life scale was used to measure quality of life. Results: Patients with HIV infection scored significantly higher on scores of tension, anger, depression, fatigue and frustration subscale of the SRI than those with pulmonary tuberculosis and normal controls. Scores of the SCL-90-R, somatization, depression, anxiety, hostility, phobic anxiety, paranoid ideation and psychoticism subscale were also significantly higher in patients with HIV infection than those with pulmonary tuberculosis and normal controls. Patients with HIV infection scored significantly lower in quality of life than those with pulmonary tuberculosis. In patients with HIV infection, age had a significantly negative correlation with scores of somatization, obsessive-compulsive, interpersonal sensitivity, phobic anxiety, paranoid ideation and psychoticism subscale of the SCL-90-R. but the level of education had a significantly positive correlation with somatization, obsessive-compulsive, interpersonal sensitivity, phobic anxiety, paranoid ideation and psychoticism subscale of the SCL-90-R. Conclusion: The results suggest that patients with HIV positive were likely to have higher levels of perceived stress response and psychopathology, and lower quality of life than those with pulmonary tuberculosis and normal controls.