• Computers and Concrete
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• 제5권6호
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• pp.573-597
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• 2008

Among artificial intelligence-based computational techniques, adaptive neuro-fuzzy inference systems (ANFIS) are particularly suitable for modelling complex systems with known input-output data sets. Such systems can be efficient in modelling non-linear, complex and ambiguous behaviour of cement-based materials undergoing single, dual or multiple damage factors of different forms (chemical, physical and structural). Due to the well-known complexity of sulfate attack on cement-based materials, the current work investigates the use of ANFIS to model the behaviour of a wide range of self-consolidating concrete (SCC) mixture designs under various high-concentration sodium sulfate exposure regimes including full immersion, wetting-drying, partial immersion, freezing-thawing, and cyclic cold-hot conditions with or without sustained flexural loading. Three ANFIS models have been developed to predict the expansion, reduction in elastic dynamic modulus, and starting time of failure of the tested SCC specimens under the various high-concentration sodium sulfate exposure regimes. A fuzzy inference system was also developed to predict the level of aggression of environmental conditions associated with very severe sodium sulfate attack based on temperature, relative humidity and degree of wetting-drying. The results show that predictions of the ANFIS and fuzzy inference systems were rational and accurate, with errors not exceeding 5%. Sensitivity analyses showed that the trends of results given by the models had good agreement with actual experimental results and with thermal, mineralogical and micro-analytical studies.

• Genomics & Informatics
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• 제20권4호
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• pp.46.1-46.7
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• 2022

Influenza A virus (IAV) is the most widespread pathogen causing human respiratory infections. Although polymerase chain reaction (PCR)-based methods are currently the most commonly used tools for IAV detection, PCR is not ideal for point-of-care testing. In this study, we aimed to develop a more rapid and sensitive method than PCR-based tools to detect IAV using loop-mediated isothermal amplification (LAMP) technology. We designed reverse-transcriptional (RT)-LAMP primers targeting the hemagglutinin gene. RNAs from reference H1N1 and H3N2 showed specific RT-LAMP signals with the designed primers. We optimized the reaction conditions and developed universal reaction conditions for both LAMP assays. Under these conditions, the detection limit was 50 copies for both RT-LAMP assays. There was no non-specific signal to 19 non-IAV respiratory viruses, such as influenza B virus, coronaviruses, and respiratory syncytial viruses. Regarding the reaction time, a positive signal was detected within 25 min after starting the reaction. In conclusion, our RT-LAMP assay has high sensitivity and specificity for the detection of the H1 and H3 subtypes, making it suitable for point-of-care IAV testing.

• Perspectives in Nursing Science
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• 제6권1호
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• pp.67-76
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• 2009

Recently, small and medium-sized hospitals which are located in rural areas have many difficulties in securing high quality nurses. That is because working environments for nurses in small and medium-sized hospitals in rural areas are poor compared with those of big hospitals in urban. As a result, the migration of nurses from small and medium-sized hospitals in rural areas to big hospitals in urban is continuously happening. In general, big hospitals provide nurses with high level of salary and fringe benefits. To prevent the migration of nurses, chief executive officers of small & medium hospitals in rural areas have been interested in improving nurses' working conditions including wages. Also, they have raised nurses' salary and improved working conditions. But, basically these individualized efforts have some limit. In connection with this, medical interest groups have produced various voices in terms of interpretation and solutions for these issues. However, from the future perspectives, it seems evident that two approaches for both manpower supply and demand plans of nurses are necessary. They should contain not only accurate estimation of the supply-demand of nursing manpower but also the improvement of working conditions and wages of nurses. Estimation of nursing manpower supply-demand depends on the standards and criteria being used. Supply and demand may be met or not in accordance with the points emphasized on the decision. In the articles, issues regarding nursing manpower, levels of salary, other working conditions and social support system for child care are discussed. According to Joe's report (2005), most health institutions did not meet the guidelines of nurse staffing in Medical Law. The wages of nurse vary on every hospital and there is a big difference in wages' range. The average starting salary for a nurse is 22 million won a year. In case of tertiary hospitals, it reaches up to 30 million won a year. Nurse as a profession should have a strong responsibility and should take care of the patients for 24 hours with three working shifts. Also, most of them are female who have the burden of child rearing. Therefore, it is suggested to increase the salary, to provide comfortable working conditions, and to have social support system for nurses with household affairs.

• 아동학회지
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• 제30권6호
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• pp.223-235
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• 2009

Elementary education in Korea has variously changed and developed during the last thirty years. Among all the progressive changes, the improvement of teaching conditions is considered to be the most fundamental one. The number of students assigned to a class or a teacher has decreased to a considerable extent. Cyber teaching-learning has been peformed at school and home, and English education has been emerged as a significant part of the Korean public education. The research issues constantly considered essential over the past three decades starting in the 1980's are those related to curricula, teaching-learning methods, training of teachers in-service, and education for upright characters. The practical and political issues should be dealt with to revise the three integrated subjects and text books into a sole integrated subject and text book, to double the credential of teachers in terms of professionalism and to decrease the number of students per teacher in Korea to the OECD level.

• 대한기계학회논문집B
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• 제27권1호
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• pp.84-94
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• 2003

It is known that tip clearance flows reduce the pressure rise, flow range and efficiency of the turbomachinery. So, the clear understanding about flow fields in the tip region is needed to efficiently design the turbomachinery. The Navier-Stokes code with the proper treatment of the boundary conditions has been developed to analyze the three-dimensional steady viscous flow fields in the transonic rotating blades and a numerical study has been conducted to investigate the detail flow physics in the tip region of transonic rotor, NASA Rotor 67. The computational results in the tip region of transonic rotors show the leakage vortices, leakage flow from pressure side to suction side and their interaction with a shock. Depen ding on the operating conditions, toad distributions and the position of shock-wave on the blade surface are very different close to the blade tip of the transonic compressor rotor. The load distribution and the shock-wave position close to the blade tip had the close relationship with the starting position of leakage vortex and the direction of leakage flow.

• 한국미생물·생명공학회지
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• 제19권2호
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• pp.135-139
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• 1991

Tridecanedioic acid (DC-13), starting material of the valuable musk ethylene brassylate, was obtained from n-tridecane by the Candida tropicalis mutant. The mutants were first obtained from primary screening step using the selective medium and then solid phase extraction sampling method was used for the selective isolation of organic acids from the cultured media of mutants. The resulting acids were directly converted to volatile tert-butyldimethyl silyl delivatives, which were then analyzed by gas chromatography. The efficient GC profiling method was used for the rapid identification of the mutant producing DC-13 in large quantity, and for the optimization of the culture conditions of mutant. The optimal culture conditions were found as follows: pH 8.0, 30$^{\circ}C$, 250rpm, 48hour of culture and $(NH_4)_2HPO_4$ as nitrogen source.

• Corrosion Science and Technology
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• 제14권6호
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• pp.288-295
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• 2015

The present work addresses crevice and galvanic corrosion processes occurring at the cylinder head gasket/cylinder head interface and cylinder head gasket/cylinder liner interface of four-stroke medium-speed diesel engines for marine applications. The contact between these systems and the marine environment can promote formation of demanding corrosion conditions, therefore influencing the lifetime of the engine components. The electrochemical behavior of various metals and alloys used as head gasket materials (both ferrous alloys and copper alloys) was investigated. The efficacy of corrosion inhibitors was determined by comparing electrochemical behavior with and without inhibitors. In particular, crevice corrosion has been investigated by electrochemical tests using an experimental set-up developed starting from the requirements of the ASTM G-192-08, with adaptation of the test to the conditions peculiar to this application. In addition to the crevice corrosion resistance, the possible problems of galvanic coupling, as well as corrosive reactivity, were evaluated using electrochemical tests, such as potentiodynamic measurements. It was possible to quantify, in several cases, the corrosion resistance of the various coupled materials, and in particular the resistance to crevice corrosion, providing a basis for the selection of materials for this specific application.

• 한국직업건강간호학회지
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• 제25권4호
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• pp.300-310
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• 2016

Purpose: Few studies have considered the psychosocial work environment factors in relation to employee health. This study explored the relationship between psychosocial work characteristics and self-rated health among Korean employees. Methods: The study population of 21,476 employees was derived from the 2014 Korean Work Environment Survey (KWES). Psychosocial work environment was measured by Copenhagen psychosocial questionnaire scales. Results: Among employees at workplaces (n=21,476), 23.3% rated their health as poor. Among 12 indicators of psychosocial work environment characteristics, 'higher emotional demand', 'demands for hiding emotions', 'work-family conflict', and 'social community at work' were independently associated with risk of poor self-rated health of Korean employees after adjustment of all sociodemographics, work condition characteristics and physical work environment exposure. In addition, higher 'possibilities for development' and 'social support from supervisor' were more likely to decrease the risk of poor health. Conclusion: We suggest that psychosocial work environment is an important determinant of employees' health. The study results provide a good starting point for developing intervention and strategies for health improvement.

• 조명전기설비학회논문지
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• 제28권8호
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• pp.75-81
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• 2014

It has been widely accepted that open phase may separate one of the power lines from power supply which is mainly caused by fuse melting, malfunction for source circuit breaker, contact failure, and disconnection under normal operating conditions, and is considered a kind of failure mode during disconnection of neutral wires as well. When open phase occurs, unequal voltage between phase might happen in the unbalanced load connected each phase, and further, depending on conditions of load, malfunction by providing low voltage. Moreover, load could be burned or overheated with overvoltage, which, in turn, can be a contributor to starting fires. Accordingly, in order to clearly overcome these problems, the current study aims to introduce the theory of uninterruptible power open phase compensation device, meaning that unbalanced power automatically restores balanced power and provides continuously the power supply without blackout, and verify it through simulation and experiments.

• 대한기계학회논문집B
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• 제33권11호
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• pp.869-875
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• 2009

The purpose of this paper is to investigate the optimal condition of the syngas production by reforming of propane using Gliding arc plasma reformer. The gliding arc plasma reformer in 3 phases has been newly designed and developed with a quick starting and fast response time. It can be applicable to the various types of fuels (Hydrocarbons $C_xH_y$), and it has a high conversion rate of fuels and high production of hydrogen. The parametric screening studies were carried out according to the changes of a steam feed amount i.e., steam/carbon ratio, total gas flow rate and input electric power. The optimum operating conditions were S/C ratio 2.8, total gas flow rate of 14 L/min and input electric power of 2.4 kW. The result of optimum operating conditions showed the 55 % $H_2$, 14 % CO, 15 % $CO_2$, 10 % $C_3H_8$ and 4 % $CH_4$. Also, $C_3H_8$ conversion, $H_2$ yield and $H_2$ selectivity were 90 %, 42 %, 15 %, respectively. The energy efficiency and specific energy requirements were 37 % and 334 kJ/mol respectively.