• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.24-31
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• 2024

Mortar has been applied in most previous studies on 3D concrete printing. In such cases, however, the economic efficient cannot help decreasing due to higher binder contents and larger amount of fine aggregates. In order to enhance the applicability of 3D printing technology to construction industry, therefore, 3D concrete printing technology utilizing coarse aggregates needs to be developed further. This study aims at proposing the mix design process of concrete containing coarse aggregates for 3D printing. Based on extensive literature review and experimental studies, the mix proportion suitable for 3D printing has been derived, and the extrudability of concrete with coarse aggregates has been verified through 3D printing tests. The primary variable of the extrudability tests was the contents of viscosity modifying agent (VMA), and the extrudability was quantitatively evaluated by measuring dimensions, distribution of aggregates, and surface quality of 3D-printed filaments. The test results showed that the dimensional suitability and surface quality were improved as the VMA contents were larger, and the coarse aggregates were evenly distributed in the section of filament regardless of the VMA contents. Based on the test results, the mix design process for concrete containing coarse aggregates for 3D printing has been proposed.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.341-344
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• 2008

Lightweight concrete is known for its advantage of reducing the self-weight of the structures, reducing the areas of sectional members as well as making the construction convenient. Thus the construction cost can be saved when applied to structures such as long-span bridge and high rise building. However, the lightweight concrete requires specific mix design method that is quite different from the typical concrete, since using the typical mix method would give rise the material segregation as well as lower the strength by the reduced weight of the aggregate. In order to avoid such problems, it is recommended to apply the mix design method of self-consolidating concrete for the lightweight concrete. Therefore experimental tests were performed as such mechanical properties(compressive strength, dry density and structural efficiency) of concrete and dry shrinkage according to ACI committee 209.

• International Journal of Highway Engineering
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• v.19 no.5
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• pp.77-88
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• 2017

PURPOSES : It is necessary to clarify the rheological properties of cement paste as a basic research in the development of mechanistic concrete mix design. The rheological properties of cement paste with different binder types, mix propositions, and with/without high range water reducers have been analyzed. METHODS : In this study, ordinary Portland cement, fly-ash, blast furnace slag, silica fume, and limestone powder were used as binders. The range of water-binder ratio was 0.3-0.5, and a total of 30 different mixes have been tested. The slump flow test, V-funnel test, and Dynamic Shear Rheometer (DSR) test were performed to analyze the rheological properties of cement paste. RESULTS : As a result of the slump flow test, it was found that the composition ratio of the binder contents greatly affected the paste flow when the high range water reducers were added. The results of V-funnel test showed that when the water-binder ratio was decreased without high range water reducers, the binder composition ratio had a large effect on the passing time of the V-funnel tester, but with high range water reducers the impact of the binder composition ratio was decreased. The slump flow and V-funnel have a certain relationship with the rheological factors (yield stress and plastic viscosity), but the correlation was not significant. Finally, we proposed the M-value considering the density and specific surface area of the binder. The correlation between rheological factors and M-value were better demonstrated than experimental values, but there is still a limit to predict the rheological factor in general mix design. CONCLUSIONS :In this study, the rheological properties of cement paste were analyzed. The binder type, composition ratio of binder, and with/without high range water reducers have combined to provide the complex effects on the rheological properties of cement paste. The correlation between the proposed M-value and rheological factor was found to be better than experimental results, but needs to be improved in the future.

• Journal of Fashion Business
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• v.8 no.2
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• pp.91-101
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• 2004

This research classified fashion merchandisers into different categories depending on the type of companies they worked for and inquired into their line of work. In so doing, the authors attempted to outline the work for merchandise mix performed by each type of merchandiser and provide some raw data, which can be utilized to enhance their work efficiency. The evaluation tool used for this study was the questionnaire made on the basis of preceding studies, literature, and trade journals, which was then modified through one on one interviews with fashion merchandisers. The questionnaire contained 15 questions about merchandise mix. For data analysis, SPSS Package Program was used to conduct frequency analysis, ANOVA, and Tukey's test. The findings are as follows 1. National brand merchandisers spent most time on merchandise planning, then department store buyers, followed by imported brand merchandisers, and lastly buying office merchandisers. 2. In merchandise planning, National brand merchandisers did more work overall compared to other merchandisers. In production planning, buying office merchandisers spent more time than any others on searching for new suppliers and decision-making. 3. Production planning took up a greater portion of their work for National brand merchandisers and buying office merchandisers compared to department store buyers and imported brand merchandisers. 4. Imported brand merchandisers spent more time on purchase planning and actual purchase compared to any others.

• Korean Institute of Interior Design Journal
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• v.21 no.3
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• pp.111-118
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• 2012

The purpose of this study is to focus on living rooms that are preferred as a place for changing space image to the maximum and to find a method how finishing materials are expressed by selecting space with mix & match of many images. The study methods are as follows. First, understand the expressive trend of space images through the precedent studies and magazines, and examine its relationship with finishing materials. Second, select space images based on the contents understood earlier and extract adjective words that represent each space image through an expert survey. Third, find the cases where space images are expressed based on the extracted words and analyze expression methods of finishing materials. The results of the study are as follows. First, it was confirmed that recent space images are actively expressed through finishing materials. Second, space images selected through data related to the trend were classified as modern+natural, modern+traditional, modern+retro, classic+natural, classic+humor, and futurism+natural and 4 adjective words for each space image were extracted. Third, expressive elements of finishing materials were extracted as 'material'. 'texture', 'color', and 'pattern' through the precedent studies. Fourth, expressive methods of finishing materials for each space image could be suggested by analyzing the examples that show mix & match based on the contents extracted earlier. Lastly, it is expected to find various methods that lead space image into finishing materials by evaluating responses and changes in visual perception of residents according to expression of finishing materials based on this study.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.9 no.6
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• pp.153-161
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• 2014

This study is to contribute to the policy decision of cosmetic industry through analyzing marketing mix factors which affects customers' buying intention. For this study, marketing mix factors that impact on cosmetic customers purchasing intention were collected and chi-square independence analysis of SPSS and qualitative analysis technology of Kano & Timko were used. Analysis reached one conclusion, which factors were maximizing customers satisfaction, shows the price discount policy and recommendation from family and colleague. Product's effectiveness, usefulness and skin compatibility were rated as an one-dimensional quality as those factors were linearly affected when customers needs were satisfied. However product's containers, package design, colors, brand reputation, low and middle price, distribution channel and advertising medias were investigated as an indifferent quality and they were rated as low satisfaction/dissatisfaction coefficient of Timko. Therefore they do not need to invest to those factors too much budget for attaining customers' buying intention.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.513-520
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• 2018

Since Paris Climate Change Conference in 2015, many policies to reduce the emission of greenhouse gas have been accelerating, which are mainly related to renewable energy resources and micro-grid. Presently, the technology development and demonstration projects are mostly focused on diversifying the power resources by adding wind turbine, photo-voltaic and battery storage system in the island-type small micro-grid. It is expected that the large-scaled micro-grid projects based on the regional district and town/complex city, e.g. the block type micro-grid project in Daegu national industrial complex will proceed in the near future. In this case, the economic cost or the carbon emission can be optimized by the efficient operation of energy mix and the appropriate construction of electric and heat supplying facilities such as cogeneration, renewable energy resources, BESS, thermal storage and the existing heat and electricity supplying networks. However, when planning a large residential town or city, the concrete plan of the energy infrastructure has not been established until the construction plan stage and provided by the individual energy suppliers of water, heat, electricity and gas. So, it is difficult to build the efficient energy portfolio considering the characteristics of town or city. This paper introduces an energy mix optimization(EMO) method to determine the optimal capacity of thermal and electric resources which can be applied in the design stage of the real large-scaled residential town or city, and examines the feasibility of the proposed method by applying the real heat and electricity demand data of large-scale residential towns with thousands of households and by comparing the result of HOMER simulation developed by National Renewable Energy Laboratory(NREL).

• Magazine of the Korea Concrete Institute
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• v.16 no.3 s.80
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• pp.50-57
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• 2004

• 한국도로학회:학술대회논문집
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• 2002.10a
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• pp.75-80
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• 2002

• 한국도로학회:학술대회논문집
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• 2010.03a
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• pp.9-17
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• 2010