• The Journal of the Korea Contents Association
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• v.8 no.10
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• pp.20-26
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• 2008

The quality of stream remaking is decided the load of a server and Jitter through the traffic of the transmission path between end to end. In order to improve these problems in this paper, I propose tree construction method of low-delay-level-multicast. In this case which the network congestion will be occurred by streaming quality, I also propose the technique which dynamically changes the transmission path. This technique first constructs the overlay structure for relaxing the overload of server. Secondly, in order to decrease Jitter of client, it makes upload bandwidth and low latency balanced. In the evaluation of the performance, this paper showed better enhancement of about $15%{\sim}24%$ than P2CAST[4] in the simulation about node average join count, average bandwidth, service request refusal ratio, RTT measurement of nodes, and node average join count by defect ratio.

• Explosives and Blasting
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• v.31 no.1
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• pp.76-86
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• 2013

In order to control tunnel blast vibration for adjacent facilities using electronic detonator, Understanding about the characteristics of near-field ground vibration is necessary. The purpose of this paper is to analyze effects of Cut-area and Extension-area vibration in relation to decision of tunnel blast vibration. These data were obtained at the top monitoring positions while ${\bigcirc}{\bigcirc}{\bigcirc}$ tunnel site of "Wonju~Gangneung double railroad section ${\bigcirc}{\bigcirc}$ construction" was passing under the existing road. Thus, tunnel blasting was conducted by tunnel electronic blasting system with 0.01% high delay-time accuracy. It can be possible that not only keeping maximum charge per delay-time but also preventing amplification of vibration which is occurred by delay-time scatter using common detonators. Additionally, V-Cut was changed into Burn-Cut. The results was presented that vibration level of extension-holes were higher than Cut-holes. Therefore, near-field ground vibration can be effectively minimized using electronic detonators in the Cut area. And also more effective way to reduce tunnel blast vibration is full-face blast using electronic detonators.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.9-15
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• 2018

According to the development and use of self-consolidating concrete in field, interest in material properties of early-age concrete is rising. Setting time with hydration process of cement is one of significant indicator to evaluate the early-age material properties of concrete, various nondestructive methods including penetration resistance measurement have been proposed to estimate setting time. This study performed an experimental approach to evaluate setting time delay in mortar adding superplasticizer using electrical resistivity measurement. For this purpose, total nine types of mortar samples were prepared, and its electrical resistivity was monitoring during 24h after mixing. From the experimental result, rising time of electrical resistivity was used to evaluate setting delay of mortar, and penetration resistance was also measured for comparison. In addition, dynamic elastic modulus and compressive strength of 1day mortar were measured to investigate a possibility the use of electrical resistivity measurement for evaluation of early-age material properties.

• Korean Journal of Construction Engineering and Management
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• v.9 no.5
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• pp.104-115
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• 2008

Currently, reconstruction and remodeling are conducted to improve the performance of aged housing. Recently reconstruction has caused many problems such as wastes generation, wasting resources and real estate speculation, remodeling is drawing attention. Accordingly, remodeling business for aged housings gradually increasing, but the use of scheduling method not considering characteristics of remodeling deters construction in some construction types. Especially, in case of dismantling construction, the dismantling is delayed since the scheduling method not considering characteristics of remodeling is used. In case of remodeling, dismantling construction is ahead of other processes, if the dismantling construction is delayed, whole construction will be delayed and if speedy construction is conducted, the costs for remodeling will increase. Furthermore, existing remodeling for aged housing has been for rahmen(crossbeam and pillar) structure apartments, but since most apartments to be remodeled are wall-slab structure where dismantling takes a lot of weight, it is highly possible the dismantling construction is delayed. Thus, this paper is to establish scheduling method for the dismantling construction reflecting characteristic of remodeling to prevent delay of dismantling construction for remodeling of aged housing with wall-slab structure.

• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.791-800
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• 2009

Multicasting is fundamental to many ad hoc network applications requiring collaboration of multiple nodes in a group. A general approach is to construct an overlay tree and to deliver a multicast packet to multiple receivers over the tree. This paper proposes adaptive overlay trees (AOTs) on wireless ad hoc networks of static nodes for delay- and energy-efficient multicast. A tradeoff function is derived, and an algorithm for AOT construction is developed. Note here that the requirements of delay and energy consumption may vary with different classes of applications. By adjusting parameters in the tradeoff function, different AOTs can be adaptively chosen for different classes of applications. An AOT is constructed in O(ke) time where e is the number of wireless links in a network and k is the number of member nodes in a multicast group. The simulation study shows that AOT adaptively provides tradeoffs between the fastest multicast (which is the choice if delay is the most important factor) and the most energy efficient multicast (which is used when energy consumption is the primary concern). In other words, one of AOTs can be appropriately chosen in accordance with the operation requirement.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.442-445
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• 2003

The purpose of this study is to present an improved lift-up & procurement work flow for effectiveness of resources increase in building construction. The current lift-up & procurement work flow has some waste factors; complicated information system, connection lack with process and decision-making delay. Therefore the study applied the value stream mapping methodology for improvement of current lift-up & procurement work flow. The main contents of the study are as follows; 1) A problem of current work flow were analyzed through current state mapping(CSM). 2) An improved work flow was suggested through future state mapping(FSM). 3) An improvement effect analysis of information system and lift-up planning The study recommends that continuous improvement of lift-up & procurement work flow and efficient management of information in building construction.

• Korean Journal of Construction Engineering and Management
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• v.5 no.1 s.17
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• pp.133-139
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• 2004

The purpose of this study is to present an improved lift-up &procurement work flow for effective resource utilization in building construction. The current lift-up &procurement work flow has some waste factors; complicated information system, connection lack with process and decision-making delay. Therefore the study applied the value stream mapping methodology for improvement of current lift-up &procurement work flow. The main contents of the study are as follows; 1) Problems of current work flow were analyzed through current state mapping(CSM). 2) An improved work flow was suggested through future state mapping(FSM). 3) An improvement effect analysis of information system and lift-up planning was investigated. The study recommends continuous improvement of lift-up &procurement work flow and efficient management of information in building construction as a future research.

• Korean Journal of Construction Engineering and Management
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• v.11 no.5
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• pp.3-14
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• 2010

This study investigated and analyzed feasibility analysis case studies, carried out by contractor of EPC LSTK projects in the planning stage to suggest the strategies to solve problems for project improvement. For this, five feasibility analysis case studies of gulf cooperation council (GCC) countries were reviewed and investigated. The results can be summarized as follows: 1) Those factors needed to be analyzed, including cost increase, project delay, quality decrease were insufficiently considered when assessing feasibility. 2) And improvement strategies for three problems mentioned above were suggested based on findings in feasibility analysis. 3) Lastly the process of the project feasibility analysis that can be applied to overseas plant construction project was suggested step by step.

• Korean Journal of Construction Engineering and Management
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• v.2 no.3 s.7
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• pp.101-109
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• 2001

Application of system form is very effective to continuous horizontal or vertical walls of the apartment housing. Though the system forms that are used in the construction field have the advantage of concrete quality improvement and increasing number of usages, there are some problems in reaching early planning scheduling goal due to schedule delay and low productivity. This study is initiated to solve the problem and suggest some improvements searching for reasons that diminish the productivity. A case study was done in apartment construction field where system form was used and the productivity is analyzed by work sampling. Finally, productivity improvements for assembly of the form, internal form and external form are suggested, respectively.

• Korean Journal of Construction Engineering and Management
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• v.6 no.6 s.28
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• pp.90-97
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• 2005

Poor usage of work-continuity for planning and management is one of the leading causes of decreased productivity in high-rise and complexity construction projects. For efficient finish work, tact scheduling method needs to be implemented according to tact time. But there are the studies about zoning of work area, daily construction information and tact planning and management, there are not the studies about tact time yet. The purpose of this study is to help implementation of tact scheduling by tact time and adjusted work-plan. The main contents of this study are as follow; (1)Tact time has been calculated as coordination of work-plan between a general contractor and specialties. (2)Project-plan can be without delay by tact time calculation method.