• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.267-276
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• 2022

Modelling the energy release performance of energetic material combustion in closed systems is of fundamental importance for aerospace and defense application. In particular, to compensate for the disadvantage of the combustion of single energetic material and maximize the benefits, a method of combusting the mixed energetic materials is used. However, since complicated heat transfer occurs when the energetic material is combusted, it is difficult to theoretically predict the combustion performance. Here, we suggest a theoretical model to estimate the energy release performance of mixed energetic material based on the model for the combustion performance of single energetic material. To confirm the effect of parameters on the model, and to gain insights into the combustion characteristics of the energetic material, we studied parameter analysis on the reaction temperature and the characteristic time scales of energy generation and loss. To validate the model, model predictions for mixed energetic materials are compared to experimental results depending on the amount and type of energetic material. The comparison showed little difference in maximum pressure and the reliability of the model was validated. Finally, we hope that the suggested model can predict the energy release performance of single or mixed energetic material for various types of materials, as well as the energetic materials used for validation.

• Structural Engineering and Mechanics
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• v.58 no.2
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• pp.217-230
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• 2016

Effects of temperature dependent material properties on mixed mode fracture parameters of functionally graded materials subjected to thermal loading are investigated. A domain form of the $J_k$-integral method including temperature-dependent material properties and its numerical implementation using finite element analysis is presented. Temperature and displacement fields are calculated using finite element analysis and are used to compute mixed mode stress intensity factors using the $J_k$-integral. Numerical results indicate that temperature-dependency of material properties has considerable effect on the mixed-mode stress intensity factors of cracked functionally graded structures.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.137-138
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• 2023

This study proposed the optimal mixing time for pre-mixed cement and post mixed cement using the statistical analysis method of box plots. Pre-mixed cement can prevent material seegregation, strength loss, and quality variation if mixed for at least 60 seconds, and the data median is shown to be within the box range. Post-mixed cement should be mixed for at least 180 seconds to prevent material segregation, strength loss, and quality variation, and compressive strength tends to increase with longer vibrating times. Therefore, it is suggested that using pre-mixed cement can shorten the vibrating time and increase the productivity of the concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.4
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• pp.129-137
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• 2002

In this study, mixed-mode fracture behavior is simulated effectively through the numerical method using the axial defomation link elements which can predict the behavior of quasi-brittle material. The behavior of quasi-brittle material is modeled numerically using the exponential tension softening constitutive equation and verified by comparing with the result of published experimental result. In order to verify the mixed-mode fracture behavior through the developed numerical method, analysis of mode I is formulated and the result is compared with those of FEM first, and then mixed-mode analysis is analyzed and compared with existing theories and experimental data. Also the characteristics of fracture behavior is examined through the analysis of crack generation with respect to various mode mixity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.503-506
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• 2000

Molecular switching in azobenzene mixed monolayers on a water surface was investigated by means of Maxwell displacement current(MDC) measurement. It was found that the change in the vertical component of the dipolemoment of the mixed monolayer during visible light irradiation was almost the same as that flowing during UV light irradiation. Also MDC was generated but it depended on the molar ratio. As a result. It's phtoisomerization progressed by 8A5H in mixed films.

• Journal of the Korean Ceramic Society
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• v.53 no.4
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• pp.381-385
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• 2016

Recently, white LEDs, especially, warm white LEDs have been intensively investigated due to outstanding optical properties, long term stability and low power consumption. In this study, mixed type and patterned type of remote phosphors were prepared by screen printing process employing green and red phosphor. Each type of remote phosphor exhibited distinctive photoluminescence spectrum. For example, the mixed type of remote phosphor exhibited unique spectrum, while the patterned type showed expectable spectrum depending on the concentration of phosphors. This indicates that a small amount of red phosphor dramatically reduced the green photoluminescence in the case of mixed-type remote phosphor, whereas the effect was negligible in the patterned-type remote phosphor. The possibility of undesirable chemical reaction was further investigated by using scanning electron microscopy and X-ray diffraction.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.216-217
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• 2014

Optimum finishing position, thickness and phase change temperature of winter and summer season were selected and suitability of finishing materials was evaluated based on temperature measurement of specimens applying the coating material mixed phase change materials(PCM). As a result, when finishing position was interior and finishing thickness of coating material mixed n-Octadecane(28℃ PCM) was 4mm, thermal performance was effective. n-Octadecane in summer season and n-Hexadecane(18℃ PCM) in winter season are indicated effective on energy savings, respectively.

• Journal of the Korean Ceramic Society
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• v.53 no.4
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• pp.435-443
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• 2016

Coal ash, a material generated from coal-fired power plants, can be classified as fly ash and bottom ash. The amount of domestic fly ash generation is almost 6.84 million tons per year, while the amount of bottom ash generation is 1.51 million tons. The fly ash is commonly used as a concrete admixture and a subsidiary raw material in cement fabrication process. And some amount of bottom ash is used as a material for embankment and block. However, the recyclable amount of the ash is limited since it could cause deterioration of physical properties. In Korea, the ashes are simply mixed and used as a replacement material for cement. In this study, an attempt was made to mechanically activate the ash by grinding process in order to increase recycling rates of the fly ash. Activated fly ash was prepared by controlling the mill types and the milling times and characteristics of the mortar containing the activated fly ash was analyzed. When the ash was ground by using a vibratory mill, physical properties of the mortar mixed with such fly ash were higher than the mortar mixed with fly ash ground by a planetary mill.

• Textile Coloration and Finishing
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• v.21 no.1
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• pp.21-29
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• 2009

In order to enhance the functionality of a cotton fabric actually used as a clothing material for patients, the fabrics were treated with a chitosan/nanosilver mixed solution. The nanosilver had excellent biocompatibility, provided expectation of an additional performance, did not harm human beings, and supplements chitosan, which was disadvantaged if used alone for fabric treatment. The nanosilver was mixed thereto and a treatment effect due to a mixing ratio was considered. This study was observed through mechanical properties and hand value which were the important function. The treatment of chitosan/nanosilver mixed solution gave a smoother surface than the treatment of chitosan alone. As a result of evaluation of the forms according to KES-FB system, Koshi was deduced, and both Numeri and Fukurami were increased. Thereby, the cotton fabric was a little smooth to provide elasticity, due to the treatment of chitosan/nanosilver mixed solution. THV of the treated fabrics calculated from this basis increased at all mixing ratio as compared with the untreated fabric. The fabrics treated with chitosan/nanosilver mixed solution were shown a better THV than the fabric treated with chitosan alone.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2004.11a
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• pp.67-73
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• 2004

The aim of this study is to analyze the tendency of the interior materials used for the apartment units of Mixed-use Apartment. One hundred fourteen cases of 15Mixed-use Apartment which were completed or under construction in Seoul and Bundang area before and after the year 2000 were the examples of this research. For the purpose of this research, following contents were analyzed accordingly. 1. The units were devided into entrance, living room, kitchen, bedroom and bathroom; and finishing material of the floor, wall and ceiling of each individual space were analyzed. 2. The units was categorized into three floor spaces(py) such as 30-49py, 50-70py, 80py and above. And each interior material of different floor spaces(py) were analyzed.