• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.553-564
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• 2022

Concrete is a representative composite material that shows excellent performance in the construction field. However, it is a brittle and nonhomogeneous material and exhibits weak behavior against bending and tensile forces. To compensate for such weakens, fiber reinforcement has been utilized, and steel fiber has been recognized as one of the best material for such purpose. However, steel fiber can seriously affect the durability of concrete exposed to the marine environment due to the corrosion caused by chlorine ions. This study intended to evaluate the mechanical performance of steel fiber reinforce concrete during and after repeated wet/dry cycles in salt solution. According to the experimental results, there was no reduction in the relative dynamic modulus of concrete during the repeated wet/dry cycles in salt solution for 37 weeks. Flexural strength was not decreased after completion of repeated wet/dry cycles in salt solution. There was no sign of corrosion in steel fibers after visual observation of fractured surface. However, the flexural toughness was decreased, and this is because about half of the concrete specimen showed failure before reaching the maximum displacement of 3 mm. Although repeated wet/dry cycles in salt solution did not cause cracks in concrete through corrosion of steel fibers, specific attention is required because it can reduce flexural toughness of steel fiber reinforced concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.2
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• pp.188-195
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• 2024

Recently, the use of recycled aggregates from construction waste has been introduced as a solution for environmental problems and aggregate shortage. In spite of the various methods to promote recycling of recycled aggregate, the use of recycled aggregate as the structural aggregate has been limited because the quality of recycled aggregate(especially recycled fine aggregate) has been considered lower than that of natural aggregate. In this work, recycled fine aggregate was immersed for an hour in acrylic resin solutions of various concentrations to improve its quality, the appropriate immersion concentration was selected by measuring the absorption capacity and skeletal density of the recycled fine aggregate, and mortar specimens were prepared to evaluate the mechanical performance in order to propose a applicable treatment process to promote the use of recycled fine aggregate. According to the experimental results, as the acrylic resin concentration increased, the absorption capacity and skeletal density of the recycled fine aggregate decreased. The absorption capacity was lowest at acrylic resin concentrations around 6 to 8 %. However, among mortar specimens made of recycled fine aggregate immersed in acrylic resin solution, the compressive strength was the highest at 4 % acrylic resin concentration, suggesting that the use of higher concentration acrylic resin solution can actually lower the compressive strength of mortar.

• Explosives and Blasting
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• v.29 no.2
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• pp.59-66
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• 2011

A variety of risks caused by natural, technological and biological hazards threaten a business continuity of an organization. Business continuity is very important issue for all organizations and its proper management may control success and failure of an organization. Business continuity plan (BCP) may be defined as a management process which provides a business continuity. BCP includes risk management, operational continuity plan, response/ recovery, exercise/study and crisis communication, etc. Risk management is a systematic method to identify, analyze, evaluate and treat emergency risks and risk assessment is composed of identifying, analyzing and evaluating emergency risks. Risk assesment is the first step for making BCP. In this study, risk assessment has been conducted for sewer laying project. Through assessing risks, 18 risks that may threaten the construction operation are identified and it is founded to be that high levels of risks which require treatment are 'collapse of excavation surface', 'breakage of ground infra-facilities', 'noise & dust dispersion' and 'rise of material costs'.

• Journal of the Korean Geotechnical Society
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• v.31 no.1
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• pp.53-64
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• 2015

This study presents the experimental results of pervious blocks subjected to a series of unique inflow conditions in urban area. The measured properties include the strength, permeability, drainage capacity and runoff, and evaporation for blocks made of two different size of aggregates. Results revealed that the strength satisfies the Korean Standard regardless of aggregate size whereas the immediate runoff occurred for the block with small size aggregate. On the other hand, the block with large aggregates allowed the drainage upon the initial inflow condition, which became hampered to induce the runoff by subsequent inflow. It was attributed to the fact that the capillary water often served as the hydraulic barrier in partially saturated condition. The salient observation indicated that the runoff highly depended on the evaporation and pre-wetting condition as well as the porosity and pore connectivity. The bilinear evaporate rate that makes the degree of saturation vary also had great influence on deterining the time-dependent runoff.

• Journal of Society of Preventive Korean Medicine
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• v.11 no.2
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• pp.101-112
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• 2007

Oriental public health programs have been introduced for the purpose of providing comprehensive oriental health care services to community people including vulnerable classes, increasing the accessibility of oriental medicine and the public benefit, and further more elevating the health promotion and the quality of life of community people. Promoting these programs since 2002 in earnest, it is evaluated that it has made a lot of performances. In the other side, it showed many problems and policy issues also. This study is accomplished to analyze the problems made since the system was introduced and until now, 2007, and with this analysis, to examine policy issues and the reasonable recommendations for its development Major problems are as follows. First, fundamental notions and identity of oriental public health programs are not positioned accurately. Second, the infra-structure construction for effective propulsion of business is insufficient. Third, it is short of the capacity for program implementation of oriental public health doctors, related manpower, and health centers. Fourth, oriental health promotion programs that can fulfill the various health needs of community people are deficient. Fifth, active aid of the government and the oriental medical world as well as legal and systematical support for oriental public health programs is insufficient. As a result, to solve the problems and induce the successful settlement of the program, the policy recommendations such as (i) the fundamental notions of the program and establishment of approach strategies, (ii) reinforcement of the foundation of the program implementation, (iii) capacity enhancement of the manpower of the program implementation, and (iv) effective building of supportive system of the program are presented.

• Journal of Korea Game Society
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• v.4 no.4
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• pp.3-9
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• 2004

Expansion of internet and construction of high speed network which require multimedia services like MMORPG are exceeding the infra-structure. In this work, CBT is analyzed by focusing on the multicast routing protoco and the algorithm which is transformable to Anycast scheme from CBT scheme is suggested to adapt game traffic. Anycast routing scheme is suitable to distribute high density traffic. Simulation model was set per a number of group and group member, which enabled to reflect real environments. Performance evaluation of routing based on the characteristics of end-to-end delay of CBT and Anycast was mainly focused, The result showed that Anycast method was improved up 8.7%, 25.5%, 34.0%, 38.6% and 51.8%, 56.6% comparing with PIM-DM and CBT routing when packet site was 128, 512 and 1K byte respectively. From the simulation, CBT/Anycast routing scheme can be presented as a flexible and solid solution for the MMORPG traffic to improve the delay characteristics of game packets.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.1
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• pp.32-40
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• 2005

Recent earthquakes over magnitude 5 in the eastern coast of Korea have aroused interests in the earthquake analyses and seismic design of breakwater structures. Most of earthquake analysis methods such as equivalent static analysis, response spectrum analysis, nonlinear analysis, and capacity analysis methods are deterministic and have been used for seismic design and performance evaluation of breakwater structures. However, deterministic methods are difficult to reflect one of the most important characteristics of earthquakes, i.e. the uncertainty of earthquakes. This paper presents results of probabilistic seismic risk assessment(PSRA) of an actual caisson type breakwater structure considering uncertainties of earthquake occurrences and soil properties. First the seismic vulnerability of a structure and the seismic hazard of the site are evaluated using earthquake sets and seismic hazard map, and then seismic risk of the structure is assessed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.6
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• pp.547-557
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• 2013

The mode II fracture toughness and strength due to shear stress are important parameters in the stability of caprock and injection zone with application to geological sequestration of carbon dioxide. In this research, a short beam compression test has been used to determine the shear strength and the mode II fracture toughness for Coconino sandstone. The average value of the shear strength and mode II fracture toughness are estimated to be 23.53 MPa and 1.58 MPa${\surd}$m respectively. The stress intensity factor is suggested by finite element analysis using the displacement extrapolation method. The effect of biaxial stress and water saturation on the fracture toughness has also been investigated. The fracture toughness increases with confining stresses, but decreases by 11.4% in fully saturated condition.

• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.4
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• pp.203-208
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• 2007

Ministry of Information and Communication is pushing for IT 839 strategy that has main points : 8 major service which can develop IT industry of Korea on the whole, 3 major infra, and 9 major new growth power. Of these, RFID/USN utilizing service is expected to exert a great influence the whole industry from field that is closely related with our life to national defense, supply, construction, transportation, physical distribution, manufacture, circulation, and service. In domestic case, departure of RFID/USN field is a little bit later than advanced nation's, and a technique difference between domestic field and that of advanced nation is about 2 years. In this situation, in order to develop middleware of various field gearing RFID Tag efficiently, we have to study about user interface and data analysis technique that is used in middleware commonly. This paper searches about WPF that appears in user interface field with up-to-date technique, and embodies 3 dimension visualization information system with WPF.

• Spatial Information Research
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• v.17 no.1
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• pp.103-115
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• 2009

Recently, the seabed facility is gradually being increased based on the development of harbor and the coastal area. However, the comparison between the survey data with the chart still shows the significant differences leading to various disasters over sea accident. Therefore, in this study, the investigation on the seabed facility were performed in 5 areas through an accuracy analysis using an up-to-date surveying equipment(MBES, SSS and SBP). Based on the study more systematic management on the seabed facility, more accurate method on the surveying, and some considerations on the related policies are suggested. Through the study, we obtained more accurate measurement on depth and seabed piping forms in Jakdo and Pyong-tack, on sunken ship in a Mok-po, on seabed crater in Je-ju. In addition, it was possible to present the method for the construction of information infra and a connection with the seabed facility. The criteria on the equipment's specification, surveying method and procedures are set by the experiments and the investigation and surveying accuracy on the seabed facilities are also suggested.