• Journal of the Korean GEO-environmental Society
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• v.12 no.2
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• pp.23-33
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• 2011

In this paper, we got soil-water characteristic curve(SWCC) of Nak-Dong River's sand respectively as relative density 40%, 60%, 80% and content of silt 0%, 10%, 20%, 30%. As a result, the more the sand densify in the same silt content and the more the sand has silt in the same relative density, the change of volume water content was decreased. we have known effect of silt contents for SWCC and verified existing empirical formula of SWCC. As experiment results of soil-water characteristic curves compared to the empirical solutions, the results of van Genuchten(1980) and Fredlund & Xing(1994) were well-matched showing S type curves with experiment results. Especially the empirical solution of Fredlund & Xing showed almost same results of the coefficient of correlation($R^2$) equal to 0.99.

• Journal of Ocean Engineering and Technology
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• v.21 no.5
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• pp.55-60
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• 2007

Bellows are mechanical components which prevent the damage of system by absorption of the vibration and the displacement of axle and radial direction. Thermal piping system is expanded by the fluid of the high temperature from the heat engine inside. At this time, bellows prevent the damage of the piping due to the thermal expansion. Recently, design of bellows is required to fit some other operational environments which are not suggested in the E.J.M.A code book. And it is difficult to produce and to maintain bellows of high temperature and high pressure bemuse of its complicated shape and this causes the manufacturing cost to rise. The objective of this study is to determine optimum shape of bellows which can endure in the high temperature and high pressure. The maximum stress has an effect on the fatigue life of bellows, therefore it needs to be minimized. This study attempts to find a shape which minimizes the stress occurring in the bellows by the design of experiment. The model used in this study is not presented in the E.J.M.A code book, therefore, from the result of design of experiment we find the factors which give effects on the characteristic value and we presents the recession model using the RSM, which can predict the characteristic values depending on the change of factor values.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.911-917
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• 2013

This is a thesis about the experiment of comparison characteristic of power and exhaust gas in the same condition between diesel engine that is equipped response power 220HP turbocharger to increase effectiveness of the engine which is recently used in a lot of industry which requires high power. Resulting of the experiment with natural aspiration diesel engine and turbocharger diesel engine, difference in low speed is not significant, but in high speed, effectiveness of turbocharger diesel engine is much higher than the other one. In other hand, in exhaust gas experiment, turbocharger model exhausts more $NO_X$ and $O_2$, but it doesn't significantly affect the result when it comes with decreasing of $CO_2$ and effectiveness of increased power characteristic. As a result, the turbocharger diesel engine is economically effective comparing with the natural aspiration diesel engine.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.115-122
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• 2018

In order to conduct the "A Study on Experiment for Improvement of Water Quality in Concrete Block Using illite and $TiO_2$ Powder", as a result of the preliminary mortar experiment, water quality purification characteristic test, pollution-resistance test, fish poison test, and the related KS-equivalent tests after manufacturing the actual concrete block, the following conclusion were deduced. As a result of the concrete block functional evaluation equivalent to KS, all the conditions showed higher compressive strength. Even though increase of absorption rate, according to illite replacement in vesicular structure, was expected as a problem, it was replaced after mixing with Titanium dioxide, and then Titanium dioxide was settled in large pores of illite so there was no problem in absorption rate.

• Journal of the Korea Institute of Building Construction
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• v.16 no.4
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• pp.313-320
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• 2016

The aim of this study is to look into the metakaolin replacement ratio of blast furnace slag based alkali activated slag mortar and its mechanical characteristics according to changes in stimulant concentration. Metakaolin has high fineness, and therefore the fluidity becomes lower as the replacement ratio becomes higher. So in this study, a sufficient value of mixing water was provided to secure fluidity for the characteristic experiment, and a different W/B was derived for each specimen in order to make the fluidity identical. A characteristic experiment was conducted according to the mol concentration of NaOH, which was used as the mixing water that affects fluidity. Additionally, compressive strength measurement, observation of inner microstructure through SEM, acid resistance experiment, and neutralization resistance was conducted. The results of this study revealed that for a high concentration NaOH solution to have even fluidity, a high W/B is necessary, and the functions were enhanced, not degraded.

• Fire Science and Engineering
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• v.31 no.4
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• pp.12-19
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• 2017

The present paper is a study on the performance characteristics of organic-inorganic hybrid flame retardants. MDF plywood has been used, that are being used for the interior decoration of building structures, to make the samples for experiment according to the existing or non-existing treatment of organic-inorganic hybrid flame resistants. Later, the experiment on the measurement of flame retardant performance using a $45^{\circ}$ flammability tester and the experiment on the measurement of combustion characteristic using a cone calorimeter have been proceeded to confirm the performance characteristic of organic-inorganic hybrid flame retardants. From the result of experiments, it has been confirmed that both organic-inorganic hybrid flame retardants have merits of inorganic and organic substances, and that heat resistance, durability and adhesiveness have been largely improved. The performance on the flame retardant has also appeared with excellent effect such as the reduced generation of combustion gas and the decreased generation of smoke.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.634-637
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• 2005

A subjective index of sound quality when it hit him is required since human listening is very sensitive and complex. Sound quality evaluation it leads consequently rightly in each situation and it composes a sound quality factor. But one of the levels in interest frequency range is substitute we cannot see the tendency of frequency substitute at whole that is executes a clear voice evaluation. Design of experiment is used and dividing 12 equally in frequency domain, the sound quality using sharpness and annoyance is performed by modifying each of frequency domains. Design of experiment method reduces much number experiment very effectively and each main effect of domain solution analysis, such as a case of sharpness and annoyance, the change of domain (increase and decrease of sound pressure level, or change nil) can grasp a type of effect should have influenced to a sound quality, and it will be able to select the objective frequency domain which hits to the sound quality. Through these obtained results the physical changes of level at arbitrary frequency domain sensitivity can be adapted.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.11 s.176
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• pp.59-63
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• 2005

Since human listening is very sensitive when the sound hit him, the subjective index of sound quality is required. Therefore, at each situation of sound evaluation its composed with the sound quality factor. But, when substituting the level of one frequency band we could not see the tendency of substitution at whole frequency band during the sound quality evaluation. In this study a design of experiment is used. The frequency domain is divided into an equally 12 parts and each level of domain whether is given increase or decrease due to the change of frequency band based on 'sharp' and 'annoy' of the sound quality is analyzed. By using the design of experiment the number of test is reduce very effectively by the number of experiment and each band the main effect will be as a solution. The case of sound quality for 'sharp' and 'annoy' at each band, the change of band (increase or decrease of sound pressure or keep maintain) which will be the most effects on the characteristics of sound quality can be identify and this will be able to us to select the objective frequency band. Through these obtained results the physical changes of level at arbitrary frequency domain sensitivity can be adapted.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.1096-1101
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• 2005

In this study, the experiment of thermal performance about closed-type hybrid cooling tower was conducted. A closed type cooling tower is a device similar to a general cooling tower, but with cooling tower replaced by a heat exchanger. The test section for this experiment has the process that the cooling water flows from top part of heat exchanger to bottom side in the inner side of tube, and spray water flows gravitational direction in the outer side of it. Air contacts of tube outer side are counterflow. The heat transfer pipe used in this experiment is a bare type tube having an outside diameter of 15.88mm. In this experiment, heat performances of the cooling tower are calculated such as overall heat transfer coefficient of between the process fluid and air, cooing capacity and pressure drop.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.457-458
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• 2002

The fractal dimension is the characteristics that can quantitatively define the irregularity in natural. It is useful in describing the morphology or various rubbed surface for hydraulic piston motor instead of the stylus profiling method. But fractal parameters had not constructed on the morphological characteristic or rubbed surface because of the insufficient knowledge about a conception of fractal dimension. In this study, for the purpose or applying fractal I parameters practically, we have suggested way to establish the morphological characteristic of rubbed surface with fractal parameters, and we carried out an experiment on the lubricant friction and wear by using Ball-ON-Disk type tester. Materials were the brass and the bronze which are used to slipper-pad in the hydraulic piston motor. We searched for fractal parameters or surface structure with the digital image processing, Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Using the image processing and fractal parameters for rubbed surface in the friction and wear test, morphology of rubbed sur race can be effectively obtained by fractal dimensions.