• Journal of the Korean Geotechnical Society
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• v.25 no.9
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• pp.45-55
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• 2009

The quality of railroad trackbed fills has been controlled by field measurements of density and bearing resistance of plate-load tests. The control measures are compatible with the design procedures whose design parameter is $k_{30}$ for both ordinary-speed railways and high-speed railways. However, one of fatal flaws of the design procedures is that there are no simple laboratory measurement procedures for the design parameters ($k_{30}$ or, $E_{v2}$ and $E_{v2}/E_{v1}$) in design stage. To overcome the defect, the compressional wave velocity was adopted as a control measure, in parallel with the advent of the new design procedure, and its measurement technique was proposed in the preliminary investigation. The key concept of the quality control procedure is that the target value for field compaction control is the compressional wave velocity determined at optimum moisture content using modified compaction test, and direct-arrival method is used for the field measurements during construction, which is simple and reliable enough for practice engineers to access. This direct-arrival method is well-suited for such a shallow and homogeneous fill lift in terms of applicability and cost effectiveness. The sensitivity of direct-arrival test results according to the compaction quality was demonstrated at a test site, and it was concluded that compressional wave velocity can be effectively used as quality control measure. The experimental background far the companion study (Park et al., 2009) was established through field and laboratory measurements of the compressional wave velocity.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.1
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• pp.203-216
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• 1994

The laboratory methods for compaction of soil (KSF 2312) and for moisture of soil (KSF 2306) in combination with the soil density in place by the sand-cone method (KSF 2311) are generally used for compaction control of soils. However, these methods have limitations in number of test and in accuracy. ]n addition, they are time-consuming. Therefore, they are not adequate for speedy control of embankment compaction in a project with huge amount of earthwork. The RI (Radioisotope) gauges for measurement of soil density and/or of soil moisture are widely used for the compaction control of soils in many countries. But in Korea, they have had a limited usage and available informations for uses of RI gauges are insufficient. Therefore, this study promotes efficient and safe use of RI gauges in geotechnical engineering. In this paper, fundamental aspects such as the priciples of RI gauges, gauge inspection techniques and the applicability and limitations of RI gauges for field usage were reviewed. And a new calibration curves suitable for the Korean soils were suggested.

• Korean Journal of Construction Engineering and Management
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• v.21 no.1
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• pp.61-69
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• 2020

As the amount of information generated in the construction project increases exponentially, design and construction review have a serious impact on the success of the site. For this reason, academic and business circles have been expanding the use of BIM at the whole life, and BIM is now accepted as one of the standards used in the construction industry. However, the BIM-based design for the temporary work is used as an aid to the 2D design because there is no specialized software and there is absolutely lack of a professional engineer. The objective of this research is to develop BIM-based temporary work support system. This system minimizes human errors in BIM-based design, quantity takeoff and inspection and shortens working hours.

• Journal of the Korean Institute of Intelligent Systems
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• v.7 no.2
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• pp.70-78
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• 1997

Proportional-integral-derivative(P1D) controllers have been still widely used in industrial processes due to their simplicity, effectiveness, robustness for a wide range of operating conditions, and the familiarity of control engineers. And a number of recent papers in fuzzy systems are showing that fuzzy systems are universal approximators. That is, fuzzy controllers are capable of approximating any real continuous function on a compact set of arbitrary accuracy. In this paper, we derive the linear PID control law from the fuzzy control algorithm where all fuzzy sets for representing plant state variables and a control variable use common triangular types. We first lead a linear PD control law from a fuzzy logic control with only two fuzzy sets for error and change-of-error. And then we derive the linear PID control law from a fuzzy controller. We here assumed that the intervals of error, change-of-error, and integral error could be partitioned into arbitrary numbers, respectively. As a result, a linear PID controller is only a sort of various fuzzy logic controls.

• Korean Journal of Construction Engineering and Management
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• v.12 no.6
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• pp.120-129
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• 2011

An installation of the construction lift has a few limitations by many constrains and these have influences on labor productivity, that can be changed by vertical-transportation management. In the super-tall building construction, a management of construction lift operation is one of the most important factor, but existing methodologies depend on skilled practitioners' experiences. And it is true that the expertise resulted by the experiences does not transfer to the next generation. This study is a part of lifting-management simulation development which aims at the optimal construction lift management. A proposed algorithm is focus on lifting time calculation considering an acceleration capability. This research evaluates the result accuracy using comparative analysis on simulation result and field measuring time.

• Journal of the Korean Geophysical Society
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• v.5 no.3
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• pp.175-198
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• 2002

The techniques using geophysical methods were adopted to obtain quantitative criteria for assessment of grouting effectiveness. Various surface and borehole geophysical surveys including seismic, GPR(ground penetrating radar), resistivity and electromagnetic methods were conducted in fractured rock pilot site before and after grouting execution. However, it is not enough that geophysical data provide criteria for field engineers to confirm the grouting effectiveness in that site even though there is somewhat difference before and after grouting. This study will be continued for the detailed criteria and assessment of grouting effectiveness in other sites.

• Korean Journal of Construction Engineering and Management
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• v.13 no.1
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• pp.129-139
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• 2012

It is one of the most important decision making problems to select the adequate foundation practice for the downtown construction project. However the foundation practice has not been selected systematically yet by considering various construction field conditions in many projects. The foundation practice is often informally selected on the basis of only past experiences and skilled engineer's opinion. For making the selection process systematically, in this study, we propose a decision support system (DSS) for selecting foundation practices based on the Analytic Hierarchy Process (AHP) and the Preference Function (PF). In the proposed DSS, the AHP is used for making the selection process more reasonable and the PF is used for considering the decision maker's preference. To validate the proposed DSS, we apply the proposed DSS to the pre-performed construction projects. The application results show that the proposed DSS gives the same foundation practices with the implemented foundation practices that the skilled foundation engineers select after carefully analyzing construction field conditions. The proposed DSS can be used as a useful tool for making decisions to select the foundation practice in the construction fields.

• Magazine of the Korea Concrete Institute
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• v.9 no.2
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• pp.145-151
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• 1997

In concrete mix design we need the informations of the codes, the specifications, and the experiences of experts. However we can't consider all factors regarding concrete mix design. The final acceptance depends on concrete quality control test results. In this process we meet the uncertainties of materials. temperature, site environmental situations, personal skillfulness. and errors in calculations and testing process. Then the mix design adjustments must be made. Concrete mix design and adjustments arc somewhat complicated, time-consuming. and uncertain tasks. In this paper, as a tool to minimize the uncertainties and errors the neural network is applied to the concrete mix design. Input data to train and test the neural network are obtained numerically from the results of design following the concrete standard specifications of Korea. The 28-days compressive strengths which are variate according to the uncertainties and errors are considered. The results show that neural networks have a strong potential as a tool for concrete mix design.

• Journal of Korean Society for Quality Management
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• v.13 no.2
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• pp.2-7
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• 1985

This paper introduces two approaches of the cost-oriented QC and the process-oriented QC, and compares them on several aspects. The cost-oriented QC tries to assure the specified quality level by sampling inspection within minimum quality cost, while the process-oriented QC aims at realization of target value of quality specification through process adjustment when a product deviates from the target. But the final purpose of both approaches is on quality assurance for markets and consumers. After all, desirability is a question of quality cost. This paper suggests two of cost functions for decision making criterion.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.244-247
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• 2002

The pile foundations have been chosen more frequently as the comprehensive development of the country progressed, especially where the ground conditions are not suitable for the construction and the dimension and the length of the piles utilized becomes larger and longer. The purpose of this study suggests the improvement method of construction management for PHC pile in an apartment house. To do This, We analyzed about current process and provided improved Process with IDEF method. And, The objectives of this research is to propose the means to solve the current problems and management factors from the results of the investigation.