• Proceedings of the Korean Institute of Building Construction Conference
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• 2004.05a
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• pp.41-44
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• 2004

Recently, in the case of domestic, for all that the deterioration environment about the carbonation of reinforced concrete structures is accelerated, systematic diagnosis and researches are not completed. And the selection techniques of repair material and method used under the situation that the indicator and the performance evaluation method are nor established are dependant on existing experience. Therefore, the purpose of this study is intend to present fundamental data for the reasonable selection of repair material and method. durability design and longevity on the deteriorated reinforced concrete structures, through computing the carbonation depth and velocity coefficient by accelerating carbonation test under various accelerating conditions and investigating the application of carbonation evaluation method. The results of this study are as follow; The resistances to carbonation are increased when the W/C ratio if lower and the treatment of surface coating is executed. And the carbonation depth and velocity coefficient according to accelerating carbonation test conditions are increased when the conditions of temperature, relative humidity and $CO_2$density are higher individually.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.6
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• pp.110-119
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• 2000

In this paper, an experimental study is carried out under the operating conditions of low speed and rapid acceleration in order to investigate and improve the response characteristics of a turbocharged diesel engine with radial turbine driven by exhaust gas. A rapid acceleration for investigating the response performance is applied to the fuel-pump rack of the engine from 0-10% to 0-40% in steps of 10%, and accelerating time of 1, 2 and 3 seconds is applied to the engine. Further experiment for improving the low speed torque and acceleration performance is also performed by means of injecting air into the inlet manifold at compressor exit during the period of low speed and application of a rapid acceleration. The effects of air injection on the response performance are represented at subjected engine speed with the changes of response performance factors such as air injection pressure, air injection period, accelerating rate, accelerating time and load. From the experimental results obtained throughout this study, it is shown that air injection into the inlet manifold at compressor exit is closely related to the improvement of low speed and acceleration performance of a turbocharged diesel engine.

• The Pure and Applied Mathematics
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• v.24 no.1
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• pp.45-51
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• 2017

In this paper, we propose an accelerating scheme of convergence of numerical solutions of fuzzy non-linear equations. Numerical experiments show that the new method has significant acceleration of convergence of solutions of fuzzy non-linear equation. Three-dimensional graphical representation of fuzzy solutions is also provided as a reference of visual convergence of the solution sequence.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.323-324
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• 2010

The purpose of this study was to investigate alkali-silica reaction of accelerating agents in shotcrete. The test was performed with accelerating agents (aluminate, alkali-free, cement based mineral admixture) in the Type I cement. As a test result, using the nonreactive aggregates, detrimental expansion due to alkali-silica reaction doesn't occurred regardless of equivalent alkali contents of accelerating agent.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.556-561
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• 2003

Flight bodies are subject to highly unstable and severe flow conditions during taking-off and landing periods. In this situation, the flight bodies essentially experience accelerating or decelerating flows, and the aerodynamic characteristics can be completely different from those of steady flows. In the present study, unsteady aerodynamic characteristics of an aerofoil accelerating at subsonic speeds are investigated using a computational method. Two-dimensional, unsteady, compressible Navier-Stokes simulations are conducted with a one-equation turbulence model, Spalart-Allmaras, and a fully implicit finite volume scheme. An acceleration factor is defined to specify the unsteady aerodynamics of the aerofoil. The results show that the acceleration of the subsonic aerofoil generally leads to a variation in aerodynamic characteristics and it is more significant at angles of attack.

• Journal of the Korean Applied Science and Technology
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• v.12 no.1
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• pp.81-86
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• 1995

Some weight loss accelerating agents, dodecyltrimethylammonium chloride(DTAC), dodecyltrimethylammonium bromide(DTAB), dodecyldimethylammonium chloride(DDBAC), polyoxyethylene(2) dodecylbenzylammonium chloride(PDBAC), and 1-(2-hydroxyethyl)-1-benzyl-2-undecylimidazolinium chloride(AEUIC), were synthesized. As a result of weight loss treatment of the weight loss accelerating agents with NaOH to PET fiber, the increase of weight loss was the order of PDBAC > DDBAC > DTAC > DTAB > AEUIC. Among the weight loss accelerating agents, AEUIC hardly showed weight loss effect, and it was separated into two layer in the NaOH solution at the treatment concentration above 6g/L, but POBAC showed good weight loss effect of 21% that approach almost to a theoretical weight loss, 21.6%, at the concentration above 8g/L.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.5-8
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• 2003

Many flight bodies are essentially imposed in gradually accelerating and decelerating free streams during taking-off and landing processes. However, the wing aerodynamics occurring in such a stream have not yet been investigated in detail. The objective of the present study is to make clear the aerodynamic characteristics of an aerofoil placed in the accelerating and decelerating free stream conditions. A computational analysis is carried out to solve the unsteady, compressible, Navier-Stokes equations which are discretized using a fully implicit finite volume method. Computational results are employed to reveal the major characteristics of the aerodynamics over the gradually accelerating aerofoil wings.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.596-598
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• 2000

This paper presents a new accelerating aging test facility for distribution lightning arresters. Aging parameters of lightning arrester are moisture ingress, electrical stress and surge absorption and so on. In this system, we applied 13.2kV to 6 samples and controled temperature and humidity of chamber and measured leakage currents of the all samples. Also we developed accelerating aging cycle which consists of -35$^{\circ}C$∼90$^{\circ}C$ temperature and 40%∼90% humidity. Through the aging test we found out the leakage current of aged sample increases rapidly according to the temperature rising. Hereafter we can determine the replacement guide of leakage current for field operating arresters and condition assessment of aged samples through this aging test.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.879-884
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• 2005

The setting time is a very important factor affecting the quality of tunnel lining and reinforcement of inclined slope etc. Currently, however, the quality criteria of accelerating admixture to improve it is not established well. In this study, evaluation on setting time measuring methods of cement mixed a accelerating admixture (AA) was performed using Gillmore and Vicat needle test methods. For both test methods, the setting time for addition at a time was better than post addition regardless of initial setting and final setting. For Gillmore needle test method, two types of measuring methods were selected and it is noted that setting time with cement type under the same accelerating admixture can be different. Accordingly, manufacturing company shall develop a less sensitive accelerating admixture to cement type. For Vicat needle test method, six types of measuring methods were used and a proper measuring method of the admixture were proposed as follows: (1) the temperature of materials used shall be controlled exactly and (2) to evaluate its properties, an admixture usage of $5\%$ (ratio of cement weight) is recommended.

• The KSFM Journal of Fluid Machinery
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• v.16 no.5
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• pp.18-23
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• 2013

Thermal aging test is performed to qualify the life time of equipment in thermally aged condition. Due to long life time more than 10 years like as in power plant, the equipment is subjected to the accelerated thermal aging condition which is able to shorten the long aging test period by increasing aging temperature. Normally, conservatism of thermal aging test causes to impose unbalanced and excessive thermal load on components of the equipment, and deformation and damage problems of the components. Additionally, temperature rise of each component through heat generation of the electric equipment leads to long-term problem of the test period. Multi-phase accelerating aging test is to perform thermal aging test in multiple aging conditions after dividing into groups with various components of equipment. The groups might be classified considering various factors such as activation energy, temperature rise, glass transition temperature and melting temperature. In this study, we verify that the multi-phase accelerating aging test method can reduce and equalize the thermal over load of the components and shorten aging test time.