• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.3
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• pp.90-96
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• 2007

Modern waste management units, so-called "landfills" protect human health and environment from hazardous leachate and gas. Accordingly, it must be constructed with a bottom liner system that includes a gas collection layer. Leachate is the contaminated liquid that drains from the waste material pollutes ground water. For this reason. bottom liner system must have durability and low hydraulic conductivity (in case of compacted clay liner, no more than $1{\times}10^{-7}cm/sec$ ). P county in Kangwon province constructed a solid waste landfill with bottom liner system. In this study. it is mainly introduced that the test results on construction and quality control of bottom liner system by "Multiple composite liner construction technology", which is selected for bottom liner system in P solid waste landfill.

• Explosives and Blasting
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• v.30 no.1
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• pp.37-51
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• 2012

In this case of "Seongnam~Yeoju double-lanes railroad construction", there were safety facilities which were concerned about damages from vibration and noise. In the project design stage, the rock-splitter method was designed to prevent them. The electronic blasting was considered to improve construction speed and economic value as an alternative tunnelling method, complying with the site's vibration criteria(cowhouse : 0.09cm/sec, residence : 0.2cm/sec). In the environment evaluation report of the eDev, tunnel electronic blasting systems, the blasting pollutions can be managed by the electronic blasting method. The results were successfully conducted with high speed construction without any damages to adjacent facilities.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.4
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• pp.397-419
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• 2012

The pressurizing support tunneling method has been developed that overcomes shortcomings of conventional trenchless methods and applied to the field. The main concept of the new method is the pressurization system which, by means of pressurization bag between outer flange of steel ribs and excavated perimeter, applies higher pressure than the pressure relaxed by excavation to the ground to prevent ground displacement. The stability of the support members and effect of displacement control of the new method were verified through 3D numerical analyses. The new method was applied to the construction of a 10.7 m wide, 7.9 m high and 85 m long ramp tunnel that passes under ${\bigcirc}{\bigcirc}$ Expressway. By applying the new method, the tunnel construction was successfully completed in 13.5 months which decreases construction time to 35% compared to conventional methods, and ground displacement was almost negligible.

• The Journal of the Korea Contents Association
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• v.9 no.8
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• pp.49-56
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• 2009

In this paper, we propose a method of energy level, node degree and selection information based CDS(Connected Dominating Set) construction algorithm for more efficient routing in ad-hoc wireless networks. Constructing CDS in ad-hoc wireless network, it is necessary to make more efficient algorithm that is faster, more simple and has low power consumption. A CDS must be minimized because nodes in the CDS consume more energy in order to handle various bypass traffics than nodes outside the set. It is better not to reconstruct CDS after constructing the most efficient CDS. To overcome this problem, we proposed the CDS construction algorithms based on EL+ND+Sel method. We compared and estimated the performance in each situation of EL + ND and EL + ND + Sel.

• Journal of Wetlands Research
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• v.19 no.4
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• pp.542-550
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• 2017

The estimations of flow characteristics and river-bed erosion or sedimentation are very important for hydraulic structure design, floodplain management, and especially, river management. The objective of the study is therefore to estimate the change of flow characteristics and river-bed change due to a hydraulic structure construction. With 11.65 km study area of the Geum River which are located in downstream of Daecheong Dam, flow characteristics and river-bed change were estimated based on the RMA2 and SED2D model. As the result of the study, the increase of river-bed sedimentation in upstream and river-bed erosion in downstream were occurred by the construction of hydraulic structure.

• Korean journal of communication and information
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• v.50
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• pp.73-93
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• 2010

This study examines the characteristics of Korean journalism ethics as job ideology by analyzing the specific conditions revealed in the historical process of the construction of Korean journalism ethics, focusing on the change of social relationships which intervene in the construction of journalism ethics. By this interpretation, this study proposes the desirable directions in journalism ethics discussion and practice strategies in the journalism field. Therefore this study analyzed the historical process and the development phase of discourse in journalism ethics in which the job position of Korean journalists have changed. In result, this study found that the discourse of Korean was used for the instrumental and rhetorical means to cope with the outside pressure in the lack of occupational self-control which becomes the premise of ethics. Because of this, the Korean journalism ethics characterize the rhetorical feature of ethical code, the structured separation of practice from cognition, the conceptual confusion of responsibility from ethics.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.37-41
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• 2008

According to the recent rapidly increasing that construction works are gradually Manhattanized mainly the grand scaled residential buildings, the foundation of the building that is related to safety is increasing for building as a grand scaled mat concrete. Because mat concrete can not be simultaneously placing of concrete in a great quantity due to the circumstance at the field, the inequal deformation of the tensile stress that according to the time lag of hydration heat between the upper layer and the lower layer is affecting as a cause that is the possibility of crack occurrence by increasing. Accordingly, this research checked the efficiency of super retard concrete in applying real structures, and we implemented the preparatory experiment to settle up the inequal deformation of the tensile stress substantially that is according to the time lag of placement between the upper layer and the lower layer by controlling the setting time using the super retarding agent. As the result of test, the more target of delay time lengthened, the more fluidity increased and air content indicated a little differences. There was from 2 to 10 hours between the standard curing and the outside curing at the setting time and in case of calculating the rate of mixing at real structure is required that mix promotion, increasing the amount of mixing, by setting up the curing temperature. The super retard concrete showed the result that in compressive strength, early-age strength was smaller than normal concrete whereas it was same or more figures from at the aging 28days because of the super retarding agent.

• Journal of the Korea Institute of Building Construction
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• v.16 no.6
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• pp.513-518
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• 2016

This study evaluates the fire resistance performance for 60MPa high strength concrete reinforced by recycling polyethylene-terephthalate(PET) fiber(fiber content : 0.05 vol.%). Because there is no fire resistance test results for circular concrete column, a fire resistance test was carried out for circular concrete column specimens. As a result, it was confirmed that PET fiber was effective against the spalling control of high strength concrete. However, the specimen with cover thickness 30mm did not satisfy the temperature standard of main reinforcement, and the specimen with cover thickness 40mm satisfied the temperature standard of main reinforcement. Therefore, more than 40mm cover thickness was demanded for stable fire resistance performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12B
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• pp.728-734
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• 2007

In this paper, we propose a GOSST(Grade Of Services Steiner minimum Tree) heuristic mechanism for the design of a physical multiple security grade network with minimum construction cost. On the network, each node can communicate with other nodes by its desiring security grade. Added to the existing network security methods, the preventing method from illegal physical access is necessary for more safe communication. To construct such network with minimum cost, the GOSST problem is applied. As the GOSST problem is a NP-Hard problem, a heuristic with reasonable complexity is necessary for a practical solution. In this research, to design the physical multiple security grade network with the minimum construction cost, the reformed our previous Distance Direct GOSST heuristic mechanism is proposed. The mechanism brings average 29.5% reduction in network construction cost in comparison with the experimental control G-MST.

• Journal of the Korea Concrete Institute
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• v.27 no.1
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• pp.55-63
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• 2015

Prefabrication technologies are making bridge construction safer and less disruptive to the environment and traveling public, making bridge designs more constructible and, improving the quality and durability by shifting site work to a more controllable environment. Modular bridge substructures with concrete-filled steel tube (CFT) piers and composite pier caps were suggested to realize accelerated bridge construction. The precast segmental pier cap consists of a composite pier table and precast prestressed segments on the table. The pier table has embedded steel section to mitigate stress concentration at the connection by small tubes. Each bridge pier has four or six CFT columns which connect to the pier cap. Shear strength of the pier cap was obtained by extending vertical reinforcing bars from the table to the precast segment. Transverse prestressing was introduced to control tensile stresses by service loadings. Structural performance of the proposed modular system was evaluated by static tests. Design requirements of the composite pier cap were satisfied by continuous reinforcing bars and prestressing tendons. Standardized modular substructures can be effectively utilized for the fast replacement or construction of bridges.