• Journal of the Korea Institute of Building Construction
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• v.10 no.3
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• pp.113-120
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• 2010

Ultra-High Strength Concrete (UHSC) demands a clear presentation of its mechanical properties, as distinct from normal strength concrete, and an evaluation of the serviceability of high-rise buildings that use ultra-high strength concrete. Ultra-high strength concrete fck=150MPa was manufactured with pre-mix cement, and an experimental study was conducted to evaluate the mixing properties and compressive strength, with the major variables being unit cement contents, water-binder ratio, and type of pre-mix cement. The test result showed that 150MPa concrete requires about 6~7 minutes of mixing time until each of the materials (ordinary Portland cement, silica fume, blast-furnace slag powder and anhydrite) are sufficiently revitalized. The slump flow of fresh concrete was shown to be about 700~800mm with the proper viscosity. The average value of concrete compressive strength was shown to be about 70% in 7 days, 85% in 14 days, and 95% in 28 days, for 56 days of concrete material age.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.57-60
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• 2007

This study is to discuss the effect of the liquid type high early strength agent considering early strength, developing strength, and economics of the concrete using admixtures. The powder type high early strength agent does not helpful because the field application is not available such as the problem of mixing process and rack of economics. To make up these subjects, the plain mixture contains the standard type AE water reducing agent, and the types of the agents are the standard type AE water reducing agent(P),liquid type high early strength agent(AD),poly carboxylate high early strength type AE water reducing agent(E1), and naphthalene + melamine high early strength type AE water reducing agent(E2). As the Contents of the agents, E1 and E2 is two types each cases, and P is one type to satisfy the target fluidity and air content, AD is three types as 0.5, 1.0,and 1.5%. In the case that AD is mixed, the fluidity is decreased, but air content is increased. For increasing strength of the early age, using OPC is more effective than FA and BS for increasing the early strength of the concrete, and if the air content is secure as plain, the effect of the developing strength can be increased because the air content is increased about 2% in the case that AD is used.

• Journal of the Korea Institute of Building Construction
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• v.19 no.2
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• pp.123-130
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• 2019

As a cold-weather-concrete construction technique for enhancing the sustainability and improving efficiency of cold-weather construction, the cracking timing, the starting point of deterioration for concrete, due to the shrinkage of the blast furnace slag cement concrete including accelerator was evaluated. As a result, by using blast furnace slag and accelerator, the cracking was developed faster with higher cracking potential under the restrained conditions at constant age and free-shrinkage strain. It can be considered that the results of decreased stress relaxation by creep or increased restraint with increased free-shrinkage strain causes the increased cracking development speed. Hence, it should be considered the necessary of cracking due to the shrinkage when blast furnace slag or accelerator was used for cold-weather construction.

• Journal of the Korea Institute of Building Construction
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• v.19 no.4
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• pp.299-306
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• 2019

In general, repair mortar is used to rehabilitate underground communities, but difficulties are encountered in the execution of long-term construction due to spatial co-operatives. In this study, the engineering properties of repair mortar according to the curing condition and accelerator type were reviewed. The results showed that the aluminate, alkali-free and calcium-aluminate precipitates in the water curing conditions showed higher compressive strength at the beginning of age than mortar specimens under air curing conditions, and increased. Especially in CA and AF test specimen with cement mineral quick setting, a large amount of ettringite products were observed compared with AL, thus reducing the pore volume and increasing the strength of the compound by micro-filling effect were found.

• Journal of Distribution Science
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• v.15 no.8
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• pp.55-64
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• 2017

Purpose - PB products at convenience stores take up about 20% of all products, and strategies for differentiation from other companies and brand image building are very important. This study would investigate the strategy for differentiating PB products and successful brand building strategy, focusing on BGF Retail that is operating 'CU', the leader in the convenience store industry in Korea. Research design, data, and methodology - This study would attempt to make an exploratory approach to PB products limited to those in convenience stores. As a research subject, this study chose BGF Retail, the operator of CU, which is the leader in the convenience store industry in Korea and chose the case study method in order to examine the strategy for differentiating PB products in convenience stores more in depth. For this purpose, this study collected materials such as papers, newspaper articles and various reports on convenience store-related PB products and conducted an in-depth study including more practical contents through an interview with CU workers. Results - CU pursued the diversity of PB products and has had the diversity of products, more than 120 kinds. It founded a product research institute and has been in charge of the differentiation strategy from planning products to launching them. Changing the target layer of consumers to those in middle age of the 40s-50s, it succeeded in the strategy expanding the consumer class. In the long run, despite it changed the name of the company, it has built a successful image, and both revenue and operating profit have continuously grown up. Conclusions - In results, CU has reset the changing main target population, and the product research institute succeeded in the innovation of products, reflecting new trends the customers want. Through this study, the practical implications could be provided for competitors.

• Architectural research
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• v.7 no.2
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• pp.13-21
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• 2005

Throughout history, buildings have been interrelated with certain indigenous characteristics such as regional climate, culture and religions. In particular, the control of regional climate has been primarily a concern for compatibility with nature. In our modern age, technologies to control climate have been successfully developed in architecture but the consumption of large quantities of natural resources can also produce environmental problems. This study is based on the proposition that this negative trend can be minimized with architectural design that is motivated to coexist with a regional climate. This study develops these design strategies for tall office buildings by analyzing various combinations of building design configurations based on regional climates. The objective is to determine the optimum architecture of tall office buildings during the initial design process that will reduce energy consumption for regional climatic conditions. The eQUEST energy simulating program based on DOE-2.2 was used for this comparative analysis study of the energy use in tall office buildings based on architectural design variables and different regional climates. The results are statistically analyzed and presented in functional architectural design decision-making tables and charts. As a result of the comparison of architectural design consideration for tall office buildings in relation to regional climates, buildings physically need less energy consumption when the architecture is concerned with the regional climate and it produces a more reasonable design methodology. In reality, imbalanced planning which is architectural design's lack of regional characteristics requires additional natural resources to maintain desired comfortable indoor conditions. Therefore, the application of integrated architectural design with regional nature should be the first architectural design stage and this research produces the rational. This architectural design language approach must be a starting point to sustaining long-term planning.

• Korean Institute of Interior Design Journal
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• v.23 no.2
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• pp.117-124
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• 2014

As the contemporary times entered, the attention focused on the 'human's perception on a space' as much as on that a space's physical structure, so the meaning of a space became defined depending on how a person thought over and behaved in the space. As this age is the times of consilience and integration, a space accepts new technologies beyond being defined simply based on the space's structure and its shape and tries to provide different, 'strange experiences' from tho se felt by the human until now. Recently in the filed of space design, it can be seen that the spae design's connection with various technologies affects on considerable influence on the all fields of culture and arts like space marketings, media arts, exhibitions and performances as well as the buildings. Especially. the fusion of digital images and architecture is actively developed. Images possessing the moving light's attributes shine a city night and day and a building changes a city's appearance itself by adding new materials on the surface of building. It is the purpose of this study to study what new experiences the human gets and creates from his interaction with spaces based on such technological fusion. By studying some cases that used the digital media as a mediating instrument as the way presenting spatial experiences to the human, this study intended to identify what design factors were applied and to find appropriate directions for space desig in relation to what new trials can be done.

• Journal of the Korea Institute of Building Construction
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• v.17 no.2
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• pp.135-140
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• 2017

As an elementary investigation to develop vegetation concrete with a relatively low pH value, magnesia-phosphate composites (MPC) were examined according to the phosphate types including Monoammonium, Monosodium, Monopotassium, Monocalcium, Diammonium, Disodium, Dipotassium, and Diacalcium phosphates. All of the MPC binders, the ratio of magnesia to phosphate was fixed to be 7:3. MPC mortars activated with Disodium, Dipotassium, and Diacalcium phosphates showed no compressive strength gain, even at age of 28 days. Meanwhile, MPC mortars with Monoammonium and Monosodium phosphates developed 28-day compressive strength of more than 34MPa, and showed a relatively low pH value below 9.8. Hence, Monoammonium and Monosodium phosphates have potentials as an activator for producing MPC-based vegetation concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.1-4
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• 2007

This study investigated the applicability of insulation curing method with double layer bubble sheets to the man concrete subjected to cold weather. Temperature history of the mass concrete indicated that the highest temperature of center section was exhibited at $34^{\circ}C$ while the that of surface section was $25^{\circ}C$. Difference between center and surface was shown to be less $10^{\circ}C$ when the temperature of center section was peak section, and thereby associated temperature cracking index was calculated 1.5, and occurrence probability of temperature cracking was 5%, so there was no temperature cracking caused by internal restraint. No temperature crack was observed by naked eye. It was clear that early frost demage and temperature cracking could be restrained due to reducing temperature difference between inner part and outside in the case double bubble sheets applied to insulation curing method in cold weather. The maturity of mass concrete is higher than outside about $72\sim89^{\circ}$ DD, so it was demonstrated to prevent early frost demage and ensure strength excellently. Insulation curing method with double bubble sheets was more economic than heating curing method.

• The Journal of Society for e-Business Studies
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• v.16 no.3
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• pp.145-158
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• 2011

Recently, the rapidly increased use of smartphone devices provides both opportunity and problems at the same time to the telecom companies in domestic and world wide. It provides a great opportunity to overcome the market stagnation of the existing voice- centric communications, and also problems of building a highly efficient new wireless access networks to accommodate huge volume of data traffic among smart devices. Facing with the age of keen competition, telecom companies have two kinds of strategies for network transition; a strategy of building uniform LTE -based 4G networks as fast as possible, and a hybrid network enhancement strategy compounding 3G and 4G networks using HSP A+, WiFi, cloud computing, etc. It is difficult to predict which strategy will have more successful outcome in the near future. This paper studies the trends and issues of network enhancement policies and transition strategies to the 4G network era, and tries to draw appropriate and efficient ways for network enhancement and operation.