• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.6
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• pp.1053-1061
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• 2017

The study is concerned with providing the improvement method on making a reasonable and scientific decision on the damages accrued from the bid rigging in the construction work. According to the review on the precedent studies and decision cases on the damages caused by bid rigging, the representative problems include the insufficiency of the classification system on the damage calculation method and the omission of the necessary stage in the damage determination process. First, the improved classification system on calculating the damages caused by bid rigging is presented with the application to the bid rigging in the construction work by adding the ratio factor in addition to the damage calculation parameters such as price and cost. Second, the standard procedures organized with six stages is presented as the process required for determining the damages if the indemnification for bid rigging is claimed. The study becomes the foundation for resolving the problem with the undue burden on a party and for preventing the opportunity loss by resolving a dispute early through the improvement classification system and standard procedures presented in the study.

• Korean Journal of Construction Engineering and Management
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• v.4 no.4 s.16
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• pp.173-181
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• 2003

During the last few years, the use of Pre-tensioned spun high strength concrete piles(PHC pile) has been gradually increased in many construction sites. Cutting work of the concrete pile is an important task to crush a part of pile head which is compressed with more than 800$\cal{kg}f/cm^2$. It is usually performed by a crusher and three to four skilled workers. Recent analysis results of the pile cutting work reveal that it frequently makes a lot of cracks which significantly reduce the strength of the pile and is labor-intensive work. The primary objective of this study is to propose conceptual designs for developing an automated pile cutting machine. It is anticipated that the development of the automated pile cutting machine would be able to bring improvements in safety, productivity, quality as well as cost saving.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.633-642
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• 2007

Although the Load and Resistance Factor Design (LRFD) method is an advanced design approach, it does not accurately capture the interaction between individual members and structural system. A nonlinear inelastic analysis for the entire structure is required to solve this problem. According to many design codes of advanced countries, a nonlinear inelastic analysis can be applied to predict the structural behavior and strength reasonably. In this study, an LRFD design method using practical nonlinear inelastic analysis was proposed. Design examples using the proposed method waspresented, and the economical efficiency and adequacy of the proposed method was investigated by comparing the design results with that of the AISC-LRFD. It has been consequently demonstrated that the proposed method can reduce the construction cost through savings in steel.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.743-750
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• 2005

High performance concrete containing silica fume for use in bridge deck overlay emerged as a viable type of bridge deck overlay that economic advantage in construction. They have gained acceptance in Europe, America and Canada in a relatively short time due to their low cost. In this study, high-performance concretes containing silica fume were tested and evaluated in the laboratory to assess their applicability for use in bridge deck overlay. It was conducted with experiments of mechanical and durability characteristics in compressive strength, flexural strength, chloride permeability, abrasion resistance, repeated freezing and thawing cycles and deicing salt scaling resistance. Laboratory test result describe that high-performance concrete containing silica fume for bridge deck overlay application shows most outstanding capacity.

• Journal of Korean Society of Steel Construction
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• v.18 no.3
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• pp.395-403
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• 2006

Recently constructed bridges often have long spans and simple structure details considering not only the function but other important factors such as aesthetics, maintenance, construction duration and life cycle cost. Therefore, bridges require high-performance steels like extra-thick plate steels and thermo-mechanical control process (TMCP) steels. TMCP stels are now gaining wide attention due to their weldability improved strength and toughness. Recently, SM570-TMC steel, which is a high-strength TMCP steel with a tensile strength of 600 MPa, has been developed and applied to steel structures. However, using this steel in building steel structures requires the elucidation of not only material characteristics but also the mechanical characteristic of welded joints. In this study, high-temperature tensile properties of SM570-TMC steel were investigated through the elevated temperature welded joints of SM570-TMC steel were studied through the three-dimensional thermal elasticplastic analyses on the basis of mechanical properties at high temperatures obtained from the experiment.

• The Transactions of the Korea Information Processing Society
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• v.5 no.1
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• pp.40-48
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• 1998

Linear size expanders have been studied in many fields for the practical use, which make it possible to connect large numbers of device chips in both parallel communication systems and parallel computers. One major limitation on the efficiency of parallel computer designs has been the highly cost of parallel communication between processors and memories. Linear order concentrators can be used to construct theoretically optimal interconnection network schemes. Existing explicitly defined constructions are based on expanders, which have large constant factors, thereby rendering them impractical for reasonable sized networks. For these objectives, we use the more detailed matching points in permutation functions, to find out the bigger expansion constant from an equation, $\mid\Gamma_x\mid\geq[1+d(1-\midX\mid/n)]\midX\mid$. This paper presents an improvement of expansion constant on constructing concentrators using expanders, which realizes the reduction of the size in a superconcentrator by a constant factor. As a result, this paper shows an explicit construction of (n, 5, $1-\sqrt{3/2}$) expander. Thus, superconcentrators with 209n edges can be obtained by applying to the expanders of Gabber and Galil's construction.

• Corrosion Science and Technology
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• v.14 no.4
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• pp.177-183
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• 2015

Prestressed Concrete steel Cylinder Pipe (PCCP) is extensively used as seawater pipes for cooling in nuclear power plants. The internal surface of PCCP is exposed to seawater, while the external surface is in direct contact with underground soil. Therefore, materials and strategies that would reduce the corrosion of its cylindrical steel body and external steel wiring need to be employed. To prevent against the failure of PCCP, operators provided a cathodic protection to the pre-stressing wires. The efficiency of cathodic protection is governed by the anodic performance of the system. A mixed metal oxide (MMO) electrode was developed to meet criteria of low over potential and high corrosion resistance. Increasing coating cycles improved the performance of the anode, but cycling should be minimized due to high materials cost. In this work, the effects of $RuCl_3$ concentration on the electrochemical properties and lifespan of MMO anode were evaluated. With increasing concentration of $RuCl_3$, the oxygen evolution potential lowered and polarization resistance were also reduced but demonstrated an increase in passive current density and oxygen evolution current density. To improve the electrochemical properties of the MMO anode, $RuCl_3$ concentration was increased. As a result, the number of required coating cycles were reduced substantially and the MMO anode achieved an excellent lifespan of over 80 years. Thus, we concluded that the relationship between $RuCl_3$ concentration and coating cycles can be summarized as follows: No. of coating cycle = 0.48*[$RuCl_3$ concentration, $M]^{-0.97}$.

• Korean Journal of Construction Engineering and Management
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• v.7 no.2 s.30
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• pp.118-126
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• 2006

There is a greater importance for underground work designed and built in the urban areas when it comes to considering the cost-effectiveness and the period of construction commensurate with an increasing trend of skyscrapers. At this stage of underground work, it's extremely necessary to choose a proper earth retaining method. Therefore, the study has suggested the rational retaining wall method by developing the support vector machine(SVM) model as a tool to choose a proper retaining wall method applied at the stage of selecting the earth retaining method. In order to develop the SVM model, the binary SVM classifier is expanded into a multi-class classifier. and to present the feasibility of our SVM model, we considered 129 projects. Applying the 'SVM Model' developed in the study to the designing and developing stages of the earth retaining work will contribute to the successful outcomes by decreasing any changes of design from implementing the earth retaining.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2004.11a
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• pp.462-467
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• 2004

Design-build, which is defined as single source responsibility for design and construction, has been widely used in large public works since governmental formulation of measure for encouraging use of design-build in 1996. However, civic groups and small and medium sized enterprises are highlighting over-competition and unbalanced market shares of conglomerate in domestic design-bid market and insisting on decrease in the use of design-build and absorption into the lowest-price bidding. This study collected information about cost, schedule, quality, new technology adoption from 51 civil design-build projects and measured their performance.

• Journal of Korean Society of Forest Science
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• v.101 no.4
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• pp.558-566
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• 2012

This study was conducted to offer preliminary data for a natural restoration by the actual condition survey of quarries after extracting rock materials. The mountain restoration area according to a farming and fishing village organize project was restored by green landscape after quarry. However, planting tree species were died due to poor maintenance and administration after restoration works and surface soil loss and erosion occurred during a summer rainfall season because of poor slope greening. It will be needed to review restoration constructions to establish a natural friendly and flawless construction through the selection of optimum restoration works and the examination of soil and geological characteristics. In addition, it is necessary to apply cost-reducing program of restoration constructions. Quarry areas could be restored by the selection of simple and optimum construction works because the most areas were dominant in earth-sand rocks, soft-rocks, and weather-rocks. In addition, the restoration construction project should be examined thoroughly by restoration specialists during green restoration planning and review processes.