• Proceedings of the KSR Conference
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• 2011.10a
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• pp.239-244
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• 2011

Technical advancement in the field of world-class railway has brought the development of passenger safety, efficient operation and fast passenger service. The study of the railway speed-up has been progressed for a long time. As for the speed-up of trunkline railways, its design work has already promoted in some railway tacks and some track sections has already been under construction. In such a perspective we should review if the domestic signaling system is the optimal system and figure out the trend of signaling system for the speed-up that is recently applied over the world. In this way learning about justification and futurition, we should secure the national competitiveness in the long term and review the system available to international exports. Further, it is important to apply the result to the research project currently being pursued. In addition, predicting the recent international trends, we should show the direction of the future-oriented and economic signaling system.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.381-386
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• 2006

The advantages of precast production are fast construction, reduction of labor and insurance of good quality. In recently, the application of the precast production is increased in the earth retaining wall field. This paper presents the results of the numerical modelling that was carried out to evaluate the stability of precast and prestressed earth retaining wall under dynamic train loading. The two-dimensional explicit dynamic finite element method (ABAQUS) was used to carry out the numerical analyses. The train loading to act track is calculated by using the real measured phase angle data. Mainly, the displacement and acceleration of wall structure in time domain analyzed to evaluate the stability under the dynamic train load.

• Korean Journal of Construction Engineering and Management
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• v.14 no.1
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• pp.3-11
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• 2013

As construction projects became larger and longer, the need for the construction technologies and innovative construction processes has been continuously increased in construction field. In response to this trend, construction industries tried to adopt the concurrent engineering which had been normally applied for manufacturing industries to develop the products with improved quality in a reduced time. However, the application of the concurrent engineering to construction field was limited due to the lack of advanced management system and incomplete theoretical backgrounds. In this regard, this study attempted to develop a checklist for the successful application of concurrent engineering to bridge projects. To this end, this study presents the checklist for the application of concurrent engineering to construction projects. Further, the checklist was modified and updated to reflect the specific feature of the bridge construction using expert interviews. With the help of additional 188 experts, a questionnaire-based survey was also conducted to validate the checklist. In addition, using importance-performance analysis(IPA), the study identified the factors needed for intensive improvement. Consequently, the proposed checklist is expected to be useful, because it improves the applicability of the concurrent engineering in that it enables managers to monitor construction progress and further to protect the project from potential risks.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5D
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• pp.695-703
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• 2008

China water market has huge potential for increased use of BOT mode and one of the most attractive markets of doing business. However, the current China water BOT market shows that many foreign companies are retreating from the market while Chinese water companies fast growing. From the view no domestic companies have track records in China BOT water market, the research identified twenty market access barriers in terms of construction laws, regulations, BOT-related policy and the recent market situation. These are evaluated based on interview results with 10 professionals direct or indirect having a China water BOT experience. All the factors are found to be highly influential to foreign company's decision on the market participation. Among those, no fixed return policy and low water price, difficulty in water price adjustment and approval, and no government guarantees, all directly related to the project viability and under the control of government, were the most critical factors, implying government's role is the key in increasing the market competition by attracting more foreign participation on the market. In addition, new construction law regulating foreign EPC contractor's construction work, namely Decree 113, and requirement of applying competitive bidding in selecting EPC contractor in a BOT project are also considered signigicant barriers on foreign participation, which contradicts international norm and therefore necessitates an adjustment on current decision process in domestic companies.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.3-23
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• 1997

The growth in fast-track construction and repair has prompted major efforts to develop high-early-strength concrete mix compositions. Such mixtures rely on the use of relatively high cement contents and accelerator dosages to increase the rate of strength development. The measures, however, seem to compromise the long-term performance of concrete in applications such as full-depth patches as evidenced by occasional premature deterioration of such patches. The hypothesis successfully validated in this research was that traditional methods of increasing the early-age strength of concrete, involving the use of high cement and accelerator contents, increase the moisture and thermal movements of concrete. Restraint of such movements in actual field conditions, by external or internal restraining factors, generates tensile stresses which introduced microcracks and thus increase the permeability of concrete. This increase in permeability accelerates various processes of concrete deterioration, including freeze-thaw attack. Fiver reinforcement of concrete is an effective approach to the control of microcrack and crack development under tensile stresses. Fibers, however, have not been known of accelerating the process of strength gain in concrete. The recently developed specialty cellulose fibers, however, were found in this research to be highly effective in increasing the early-age strength of concrete. This provides a unique opportunity to increase the rate of strength gain in concrete without increasing moisture an thermal movements, which actually controlling the processes of microcracking and racking in concrete. Laboratory test results confirmed the desirable resistance of specialty cellulose fiber reinforced High-early-strength concrete to restrained shrinkage microcracking an cracking, and to different processes of deterioration under weathering effects.

• Steel and Composite Structures
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• v.30 no.4
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• pp.393-403
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• 2019

Cold-formed steel (CFS) has a great potential to meet the global challenge of fast-track and durable construction. CFS members undergo large buckling instabilities due to their small wall thickness. CFS beams with corrugated webs have shown great resistance towards web buckling under flexure, when compared to the conventional I-sections. However, the magnitude of global imperfections significantly affects the performance of CFS members. This paper presents the first attempt made to experimentally study the effect of global imperfections on the structural efficiency of various strengthening schemes implemented in CFS beams with corrugated webs. Different strengthening schemes were adopted for two types of beams, one with large global imperfections and the other with small imperfections. Strength and stiffness characteristics of the beams were used to evaluate the structural efficiency of the various strengthening schemes adopted. Six tests were performed with simply supported end conditions, under four-point loading conditions. The load vs. mid-span displacement response, failure loads and modes of failure of the test specimens were investigated. The test results would compensate the lack of experimental data in this area of research and would help in developing numerical models for extensive studies for the development of necessary guidelines on the same. Strengthening schemes assisted in enhancing the member performance significantly, both in terms of strength and stiffness. Hence, providing an economic and time saving solution to such practical structural engineering problems.

• Journal of the Korea Institute of Construction Safety
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• v.2 no.1
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• pp.36-44
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• 2019

$21^{st}$ century is digitally civilized era. Technologies such as AI, Iot, Big Data, Mobile and etc makes this era digitally advanced. These advancement of the technology greatly impacted detection range of the radar. Human's eye sight can see about 20Km and hear 20 ~ 20000 Hz. These limitations can be overcome using radar. This radar technology is used in military, aircraft, ship, vehicle and etc. to replace human eye. However, radar technology is capable of making False Alarm Rate. This document will propose the fix of these problems. Radar's distortion includes beam refraction, diffraction and reflection. These inaccurate data result in deterioration of human judgements and my cause various casualties and damages. Radar goes through annual testing to test how many false alarm is being produced. Normal radar usually makes 10 to 20 False alarms. In emergency situation, if operator were to follow this false alarm, this might result in following false object or take 12 more seconds to follow the right object. This problem can be overcome by using different radar data from different places and angles. This helps reduces False Alarm rate and track the object twice as fast.

• Resources Recycling
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• v.21 no.1
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• pp.30-40
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• 2012

Electric arc furnace slag is made in ironworks during steel refining, it is been increasing chemical and physical resistibility using ageing method of unstable state of melting steel slag for using concrete's fine aggregates. Which is been changing stable molecular structure of aggregates, it restrains moving of ion and molecule. In Korea, KS F 4571 has been prepared for using the electric arc furnace oxidizing slag to concrete aggregates(EFS). In this study, Electric arc furnace oxidizing slag is used in the PRCC(Polymer Rapid setting Cement Concrete) which is applied a bridge pavement of rehabilitation, largely. The results showed that the increment of compressive strength development by 10- 20%. The flexural strength of EFS-Con increased greatly as the electric arc furnace oxidizing slag changed. The compressive strength and flexural strength developed enough for opening the overlayed EFS-Con to the traffic after 4 hours of EFS-Con placement. The permeability of EFS-Con was evaluated as negligible due to its very low charge passed. Thus, EFS-Con could be used at repairing or overlaying the concrete at fast-track job sites.