• Korean Journal of Construction Engineering and Management
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• v.14 no.4
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• pp.84-96
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• 2013

Recently, architectural design has been changing from formal design to freeform design due to the digitalization of construction industry. Especially, the formal design has been accepted as a design trend recently and applied many times as a design concept in the architectural design competitions such as turn-key. However, various deflects such as water leak and cracks have been occurred because the traditional construction methods had been applied without any revision or adaptation of the formal construction method for the freeform building construction. Design and construction of freeform building has been developed as an new method in order to solve the problems and minimize the construction duration and cost for the freeform building. Therefore this research deduced the positive implications for developing freefrom envelope by analyzing the domestic and abroad cases and proposed the considerations during design and construction of the freeform envelope as follows. First, the freeform design should consider the constructability for the freeform envelope. Second, manufacturing technology for the two-way curvature of the unit panel should be developed. Third, exposed concrete form method should be developed for the freeform envelope of concrete. Forth, material characteristics, construction method and facility management should be considered in order to manage precipitation and keep water-proof according to the classification of the freeform envelope area.

• Korean Journal of Construction Engineering and Management
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• v.13 no.5
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• pp.12-24
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• 2012

The Risks in undertaking a construction project comes from many sources and often involves many participants in the project. This study has identified various kinds of risks, assessed the risk factors quantitatively and suggested risk management method for response pertinent in Design Build(Turn Key)type of projects in Korean context. A questionnaire was designed comprising of 145 possible risks in all types of construction projects. The population from owner, consultant and contractor groups was asked to indicate the risks applicable in DB projects. 25 numbers of critical risks in DB projects were identified and further analyzed for reveling inherent relationship between them through factor analysis. Factor analysis revealed 8 risk factors in DB projects. Construction site related, contract related and design related risk factor consisted about 72% of total risk weight. It has been found out about 6%, while considering the mutual dependency, it is about 10% of total cost of DB project. Therefore, It is suggested that 6% to 10% of construction amount as contingency has to be made provision for risk responses in the DB projects.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1204-1227
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• 2020

The tradeoff between energy conservation and traffic balancing is a dilemma problem in Wireless Sensor Networks (WSNs). By analyzing the intrinsic relationship between cluster properties and long distance transmission energy consumption, we characterize three node sets of the cluster as a theoretical foundation to enhance high performance of WSNs, and propose optimal solutions by introducing rendezvous and Mobile Elements (MEs) to optimize energy consumption for prolonging the lifetime of WSNs. First, we exploit an approximate method based on the transmission distance from the different node to an ME to select suboptimal Rendezvous Point (RP) on the trajectory for ME to collect data. Then, we define data transmission routing sequence and model rendezvous planning for the cluster. In order to achieve optimization of energy consumption, we specifically apply the economic theory called Diminishing Marginal Utility Rule (DMUR) and create the utility function with regard to energy to develop an adaptive energy consumption optimization framework to achieve energy efficiency for data collection. At last, Rendezvous Transmission Algorithm (RTA) is proposed to better tradeoff between energy conservation and traffic balancing. Furthermore, via collaborations among multiple MEs, we design Two-Orbit Back-Propagation Algorithm (TOBPA) which concurrently handles load imbalance phenomenon to improve the efficiency of data collection. The simulation results show that our solutions can improve energy efficiency of the whole network and reduce the energy consumption of sensor nodes, which in turn prolong the lifetime of WSNs.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.6
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• pp.533-546
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• 2007

This paper studied the design VE (Value Engineering) process among the various methods to satisfy the requirement of user and cost saving in the overall redesign process for the Turn-key base construction project. This study has been estabilished the rational and practical analysis process with the stepwise by using the design VE process. The efficiency and safety were verified with the adoptian of computer simulation to cope with the problem of initial analysis and verification for design VE process in the large construction project. In the previous design VE process, there is a limitation for the analysis of design VE in the planing stage and the execution time period of the large construction project. The previous application of VE technique was only for the construction of harbor facilities, so there was no contribution of cost saving in the function and construction. However, this paper proposed the selection methodology of VE items and hence the redesign VE process can be efficiently improved. It can be also improved the process of functional analysis rationally and practically. About 4.6 billion won has been saved with applying to the harbor construction project with using the VE method proposed in this paper. The study gives the direction of VE to be accomplished efficiently in the similar project.