• Korean Journal of Construction Engineering and Management
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• v.18 no.2
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• pp.71-80
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• 2017

In recent years, the reduction of international award and project loss by Korean contractors have become a big issue not only in industry but also in academic fields. However, many researches have not focused on small and medium subcontractors but on the large contractors, even though the number of international project by small and medium companies is more than by large companies. Therefore, this study focuses on analyzing the predicted risk before bid and the actual risk after award in international subcontracting projects. In addition, it provides the difference between project performances according to the contract types and the project profitability. This study is expected to give more informed risk knowledge to small and medium subcontractors, which enables them to pay attention to managing risk for better project performances.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4950-4959
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• 2015

The importance of public infrastructures' protection against crash or blast loads has been emerging issue as structures are becoming bigger and population densities in downtown cities are growing up. However, there exists no sufficient study which considers the developments of protective building materials, that are essential for protective design and construction. To assess the protection performance and the applicability as protective materials of high performance fiber reinforced cementitious composites(HPFRCC), this study performed the impact tests with 40 mm gas-gun propelled projectile crash machine. From this study, it has observed that both high compressive strength of cement matrix and fiber reinforcement are beneficial for the improvement of impact resistance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1413-1420
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• 2015

On the design phase of small size bridge, owing to the lack of related guidelines or standards to determine a superstructure type of bridge, many designers tend to select the type depending on expert's experience and knowledge. Moreover, recently, as types of bridge superstructure become diverse and more conditions need to be considered in the project, the decision makes process become complex. This research covered the selection of a superstructure type of a middle or small size bridge with span length of about 50m, which frequently built for national roadway, selecting type of bridge superstructure more systematic way rather than the existing ways to compare construction methods or to depend on expert's experiences. This study proposes to build a bridge superstructure type selection model using one of the techniques of artificial intelligence techniques SVM by applicability of the model examined through the verification of the actual case.

• Magazine of the Korea Concrete Institute
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• v.7 no.6
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• pp.176-185
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• 1995

The heat generation of hydration of cement causes the internal temperature rise and volum& change at early age, particularly in massive concrete structures. As the results of the temperature rise and external restraint conditions, the thermal stress may induce cracks in concrete. Therefore, various techniques of the thermal stress control of the mass concrete have been wid'dy used. One of them is pipecooling which reduces the temperature of concrete with flowing water. The objective of this paper' is to develop a finite element program which is capable of simulating the temperature history considering pipe-cooling effect. The numerical results in this study are in good agreement with experimental data measured in the footing(l1 x22m). Therefore, this study may provide available method to predict the hydration temperature of concrete with pip:-cooling.

• Journal of the Korean GEO-environmental Society
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• v.1 no.1
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• pp.87-96
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• 2000

Generally, OPC(ordinary portland cement) is used for grouting in Korea, and bentonite has usually been added to prevent the deposition of cement particles. The dispersion of CB(cement bentonite) grout is influenced by variable factors i.e. water to cement ratio, particle size of cement, kind of bentonite, adding volume, method of adding, viscosity of CB grout materials and curdling time. Among variable factors, the viscosity of CB grout materials is influenced by the dispersion, and dispersion is improved as the speed of grout mixer increase. In this paper, the specification of construction was derived by estimating physical characteristics of CB grout materials and confirming the sate of dispersion. The results show that the engineering characteristics of CB grout materials vary with the water to cement ratio and the mixing speed.

• Journal of the Korean GEO-environmental Society
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• v.8 no.6
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• pp.13-19
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• 2007

This study examines a cause for damage of synthetic resins straight pipe occurred after pipe construction of underground electric power duct pipelines of ${\bigcirc}$ section work, ${\bigcirc}$ line, ${\bigcirc}{\bigcirc}$ city railroad. For this, we analyzed a parameter used for plan and structural analysis through a literature review. And the site condition was analyzed in detail, and test construction of the pipe line that simulated the site pipe line and test on compaction by watering were performed. In addition, an examination on subsurface settlement influence of foundation ground through a structural safety and a numerical analysis of power transmission pipe line was performed. As a result of the performance, relative density gained by compaction by watering was more than average and relative degree of compaction according to technical specification standard showed the result of about 90% in the case of good compaction by watering.

• Journal of the Korean Geosynthetics Society
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• v.17 no.1
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• pp.33-43
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• 2018

Two-row Overlap Pile wall is a novel retaining wall system with high flexural rigidity and waterproofing for deep excavation support currently being developed in Korea. The Two-row Overlap Pile wall is constructed by making an overlap between consecutive four-axis (or two-axis) auger piles which themselves are overlapped and arranged in zigzag manner. In this study, the flexural rigidity of the Two-row Overlap Pile wall, including the effect of cross-sectional shape, was examined using both theoretical and numerical approaches. The results of investigation suggested that the Two-row Overlap Pile wall formed with two-row piles exhibit greatly higher flexural rigidity than conventional one-row pile walls such as Cast in place pile (CIP) and Secant pile wall (SPW), whereas the effect of overlap length between piles on the flexural rigidity is relatively minimal.

• Korean Journal of Construction Engineering and Management
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• v.5 no.6 s.22
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• pp.146-153
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• 2004

The purposes of this study are to survey unfair aspects of specific provisions in the construction contract, and to suggest counterplans and institutional reformations. The research method of this study includes judicial precedent analysis and a questionnaire survey, The results of this study are as follows: 1) the main problems of unfair specific provisions are payment condition, shifting of the responsibility and adjustment in the contract sum. 2) counterplans ate suggested according to the construction phase : bid, construction and completion phase. 3) institutional reformations include firming up regulations, supervision, invigoration of claim, development of variation guideline, and so on.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.321-325
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• 2008

3D and BIM technology are presumed to be used more and more in the construction industry. The scope of this paper arose from a general wondering of how the constructor in general can benefit from the use of 3D models. Presented herewith is the first application of BIM in Korea to a actual bridge construction site located in Cheongpoong in Chooncheongbook-Do. This paper tries to integrate design, cost and schedule under location-based conditions with industry-specific solution for 3D modeling. 292 activities constitute the cable-stayed bridge of 442m long with a main span of 327m long. Integration of 3D model, cost and schedule is shown by comparing the measurements of works at a specific time by use of 2 different construction sequencing scenarios and cost breakdown structures.

• Explosives and Blasting
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• v.22 no.1
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• pp.57-65
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• 2004

Explosive blasting in tunnel excavation produces ground vibration and air blast as its side effects, which may cause complaints from nearby residents. This study was intended to investigate the propagation characteristics of ground vibration induced by tunnel blasting and to evaluate its effects on the residential structures near the site. We have conducted field measurements for 6 blasts and acquired vibration data from 70 measuring points, some of which on positioned inside the tunnel for comparative reason. Various documentation was reviewed to determine an allowable level of peak particle velocity for the residential structures in the area and the allowable limit was set to 0.5 cm/sec. Propagation equations for peak particle velocities were derived from regression analyses using the data acquired at both the surface and the underground tunnel. Finally we proposed appropriate predictive equations for the two areas and a safe blasting criterion.