• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.421-428
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• 2020

Recently, excellent thermal and electrical performance of cementitious composites by mixing nano materials are being studied. The purpose of this study is to research the heat generation and power consumption of rapid hardening nano-cementitious composites. The experiment was carried out after setting the rapid hardening cementitious material, curing day, and supply voltage as parameters. Rapid hardening nano-cementitious materials were classified into cement paste, mortar, and concrete The heat performance of all rapid hardening nano-cementitious composites in curing 1 day has increased over 10℃. The rapid hardening nano-cementitious composites can exhibit heat performance within 1 day. The heat performance of the rapid hardening nano-cementitious composites is maintained after 28 days.

• Geomechanics and Engineering
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• v.35 no.5
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• pp.511-523
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• 2023

Canal-side roads frequently collapse due to an unexpectedly greater soft-clay thickness with a rapid drawdown situation. This causes annually increased repair and reconstruction costs. This paper aims to explore the effect of soft-clay thickness on the failure in the canal-side road in the case study of Phra Nakhon Si Ayutthaya rural road no. 1043 (AY. 1043). Before the actual construction, a field vane shear test was performed to determine the undrained shear strength and identify the thickness of the soft clay at the AY. 1043 area. After establishing the usability of AY. 1043, the resistivity survey method was used to evaluate the thickness of the soft clay layer at the failure zone. The screw driving sounding test was used to evaluate the undrained shear strength for the road structure with a medium-stiff clay layer at the failure zone for applying to the numerical model. This model was simulated to confirm the effect of soft-clay thickness on the failure of the canal-side road. The monitoring and testing results showed the tendency of rapid drawdown failure when the canal-side road was located on > 9 m thick of soft clay with a sensitivity > 4.5. The result indicates that the combination of resistivity survey and field vane shear test can be successfully used to inspect the soft-clay thickness and sensitivity before construction. The preliminary design for preventing failure or improving the stability of the canal-side road should be considered before construction under the critical thickness and sensitivity values of the soft clay.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.3-8
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• 2007

"The world is flat" as the popular author Thomas L. Friedman declares in his best belling book about the progress of business globalization in the $21^{st}$ century [3]. Construction projects and related businesses have been global since the 1800's, but it has never seen such rapid transformation in both scope and depth as in the past decade. Construction projects today often bring together international design talents, construction management firms, local and international labor forces, and global suppliers. On a visit to Dubai in the United Arab Emirates on the Persian Gulf, a person will experience the complexity of globalization of modern construction projects- with Arab owners, European engineering and design companies, American construction management teams, Korean general contractors, Jordanian subcontractors, and labor forces from Thailand, Indonesia, Turkey, and Sri Lanka. A count of material suppliers reveals over 60 countries involved, covering all continents. Indeed construction projects are getting more and more complex and competitive, as is the project execution. The trend toward globalization poses both challenges and opportunities to construction and engineering companies competing on a global scale. While global competition may be a threat to many companies, there are, however, many opportunities for synergistic collaborations that can create win-win scenarios for construction business, research, and education. This paper presents some of the opportunities between the U.S. and Asia in business integration, research collaboration on technologies, and educational development, which may mutually benefit countries on either side of the Pacific.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.217-220
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• 2015

Because of the recession of the Korean construction market, many construction companies are expediting overseas business. Despite the rapid growth of international markets, the polarization of profit with SMCCs (Small and Medium Construction Companies) and large construction companies in the international construction market has become more serious. This problem causes competition to provide the lowest prices, which makes the future of overseas business for the SMCCs uncertain. Thus, the SMCCs require a reasonable capability evaluation system for overseas business. However, the existing evaluation methods focus on large construction companies. To address this problem, this study proposes a system to evaluate the overseas business capabilities. The 27 indicators to evaluate the overseas business capabilities are derived from a literature review and are verified through expert interviews. The indicators are classified into 4 large categories, and a questionnaire-based survey of 50 Korean SMCCs is conducted to analyze the correlation between overseas business capability and the indicators. The system expects to provide the effect of the indicators on the overseas business capability and the chance to evaluate the capability for overseas business.

• Journal of the Korea Institute of Building Construction
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• v.18 no.4
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• pp.329-335
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• 2018

The objective of this study is to develop a mortar mixture with high workability and adhesive strength for section jacketing in seismic strengthening technology of existing concrete structures. To achieve targeted requirements of the mortars (initial flow exceeding 200 mm, compressive strength of 30MPa, and adhesive strength exceeding 1MPa), step-by-step tests were conducted under the variation of the following mixture parameters: water-to-binder ratio, sand-to-binder ratio, polymer-to-binder ratio, dosage of viscosity agent, and content of ultra-rapid-hardening cement. The adhesive strength of the mortars was also estimated with respect to the various surface treatment states of existing concrete. Based on the test results, the mortar mixture with the polymer-to-binder ratio of 10% and the content of ultra-rapid-hardening cement of 5% can be recommended for the section jacketing materials. The recommended mortar mixture satisfied the targeted requirements as follows: initial flow of 220 mm, high-early strength gain, 28-day compressive strength of 35MPa, and adhesive strength exceeding 1.2MPa.

• International Journal of Highway Engineering
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• v.17 no.3
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• pp.85-95
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• 2015

PURPOSES : Recently, bonded concrete overlay has been used as an alternative solution in concrete pavement rehabilitation since its material properties are similar to those of the existing concrete pavements. Deteriorated concrete pavements need rapid rehabilitation in order to prevent traffic jams on Korean expressways. Moreover, speedy and effective repair methods are required. Therefore, the use of bonded concrete overlay with ultra-rapid hardening cement has increased in an effort to reopen promptly the expressways in Korea. However, mobile mixer is required for ultra-rapid hardening cement concrete mixing in the construction site. The use of mobile mixer causes various disadvantages aforementioned such as limitation of the construction supply, open-air storage of mixing materials, increase in construction cost, and etc. In this study, therefore, hydration accelerator in-situ mixing on polymer modified concrete produced in concrete plant is attempted in order to avoid the disadvantages of existing bonded concrete overlay method using ultra-rapid hardening cement. METHODS : Bonded concrete overlay materials using ultra-rapid hardening cement should be meet all the requirements including structural characteristics, compatibility, durability for field application. Therefore, This study aimed to evaluate the application of hydration accelerator in-situ mixing on polymer modified concrete by evaluating structural characteristics, compatibility, durability and economic efficiency for bonded concrete overlay. RESULTS : Test results of structural characteristics showed that the compressive, flexural strength and bond strength were exceed 21MPa, 3.15MPa and 1.4MPa, respectively, which are the target strengths of four hours age for the purpose of prompt traffic reopening. In addition, tests of compatibility, such as drying shrinkage, coefficient of thermal expansion and modulus of elasticity, and durability (chloride ions penetration resistance, freezing-thawing resistance, scaling resistance, abrasion resistance and crack resistance), showed that the hydration accelerator in-situ mixing on polymer modified concrete were satisfied the required criteria. CONCLUSIONS : It was known that the hydration accelerator in-situ mixing on polymer modified concrete overlay method was applicable for bonded concrete overlay and was a good alternative method to substitute the existing bonded concrete overlay method since structural characteristics, compatibility, durability were satisfied the criteria and its economic efficiency was excellent compare to the existing bonded concrete overlay methods.

• Journal of the Korea Institute of Building Construction
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• v.2 no.2
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• pp.165-172
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• 2002

A reinforced concrete building neighboring in Pusan or Ulsan where is directly exposed to salt water contrasting with other in land areas contains much salt content percolated from the outside that the high salt content percolates and diffuses through the inside of reinforced concrete; therefore, an immovable tunic surrounding it begins to be destroyed and eroded with high speed. At the time, the cross-sectional area and volume expansion of re-bar reinforcing result in being cracks make a rapid progress gradually until they appear in the surface of the one, the phenomenon such as being a thin layer or falling off the part of it causes a lowering of its durability and might collapse the concrete construction. So far, we've investigated into salt content of reinforced concrete constructions neighboring in a seaside district and damage by carbonation, and we came to a conclusion as follows: $\circled1$ Under the oceanic circumstance a concrete construction is influenced by sea water directly that contains much amount of salt content contrasting with other constructions on inland areas. $\circled2$ Because of chloride penetration the carbonation of reinforced concrete made a rapid progress until more than the covering thickness of re-bar. $\circled3$ An old reinforced concrete building which has been piled up salt injury and proceeding the carbonation of its cross-sectional area. $\circled4$ According to rapidly cracking from the inside to surface of reiforced concrete, the phenomenon of being a thin layer or falling off the part of reinforced concrete results in a lowering of durability and shortening the life-time of concrete construction itself.

• Architectural research
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• v.15 no.1
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• pp.25-33
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• 2013

The amount of construction waste increased to 176,447 ton/day in 2008 from 28,400 ton/day in 2000, a 6-fold increase in just 10 years. Such dramatic increase in the waste of concrete, asphalt concrete, wood and metals was due to demolition of old buildings as well as a great number of building redevelopment projects and hurried city industrialization. Many buildings targeted for demolition today were built in line with the government policy to provide affordable housing to citizens in the shortest time possible and consequently, said buildings underwent rapid deterioration and required periodic repairs and reconstruction. Based on the above, we predict that construction waste will continue to increase for the foreseeable future. In particular, due to limited availability of suitable space to construct apartments and residential buildings in the city, old buildings are being torn down to make space for new development, further increasing construction waste. In light of that, efforts to recycle as well as reduce generated waste are urgently required.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.62-63
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• 2017

According to the rapid development of digital technology, the free formed buildings with complex and various curved surfaces are being constructed. Most of the external cladding of free formed buildings have been applied materials such as metal, glass, FRP, GFRC, etc. However, these materials have many disadvantages such as a complicated manufacturing process for realizing 3D irregular shape and an increase in production period and cost. Therefore, the studies for UHPC which is an optimized material for overcoming this problem for a long time in overseas. This study reviewed the remodeling construction of Samsung-dong KEB Hana Bank appling the exterior curved UHPC panel for the first time in Korea. As a result, we confirmed the possibility of UHPC panels with various free formed shapes.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.822-824
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• 1997

The routing and surveying a transmission line should be done in advance of its construction. It is getting more difficult to construct transmission line day by day, due to the rapid increase of people's demand resulting from the recent change of social environment and people's consciousness. In order to solve these complicated conditions actively and rationally, it is necessary to be more scientific, objective and computerizable for the routing and surveying of a transmission line. New technologies on routing and surveying a 765kV transmission line are remote sensing, Global Positioning System and Optimal PowerLine system. Thanks to these technologies, there will be a contribution to making sure of the best quality and developing technolo91r of transmission line.