• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.569-579
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• 2000

An improved multi-level (IML) optimization algorithm using automatic differentiation (AD) of framed structures is proposed in this paper. For the efficiency of the proposed algorithm, multi-level optimization techniques using a decomposition method that separates both system-level and element-level optimizations, that utilizes and an artificial constraint deletion technique, are incorporated in the algorithm. And also to save the numerical efforts, an efficient reanalysis technique through approximated structural responses such as moments and frequencies with respect to intermediate variables is proposed in the paper. Sensitivity analysis of dynamic structural response is executed by AD that is a powerful technique for computing complex or implicit derivatives accurately and efficiently with minimal human effort. The efficiency and robustness of the IML algorithm, compared with a plain multi-level (PML) algorithm, is successfully demonstrated in the numerical examples.

• Journal of Navigation and Port Research
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• v.29 no.4
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• pp.327-333
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• 2005

Sea level (MSL, MHWL, or MLWL) change has been main concern to scientists and engineers and it can be primarily due to both change of climate and vertical movement of land. This paper reports the intensive analysis of the sea level changes and broad discussion of the future at the southwestern coast of Korean peninsula. Regression analysis was conducted to investigate general tendency and periodicity of the sea levels at the six different study sites such as Gunsan-I(inner port), Gunsan-O(outer port), Mokpo, Yeosu, Heuksan and Jeju and the results were compared with global values. Besides the changes of sea levels due to global warming, the influence of the man-made structure such as seadike and seawall was attempted to quantify using the minimization of the Root Mean Square(RMS) error. The results show that it is a general tendency that the values of mean sea level rise at the southwestern coast of Korean Peninsula, especially at Gunsan-I and Jeju, are somewhat larger compared to global average values. There is also some evidence that tidal amplifications are found just after construction of man-made structure at Gunsan-I and Mokpo. However, both sites show different mechanism in relation to tidal choking, tidal flat and river discharge. The impact due to construction of man-made structure is considerably larger at Mokpo site, while the impacts due to man-made structure and the effect of sea level rise are relatively identical at Gunsan-I site. This study is expected to provide some intuition to future design.

• International Journal of Highway Engineering
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• v.10 no.3
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• pp.109-118
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• 2008

This study analyzes the change of stability of embankment due to the construction of embankment combined used road with two different construction phases. The stabilities have been checked both in the phase of earth banking for a road construction and in the phase of the application of the traffic roads(DB-24). In both cases the factor of safety has been found higher than 1.3 which is the general criterion of the safety of an embankment. The results indicate that the safety of an embankment due to the construction of embankment combined use road is assured, and thus, it is thought that the construction of embankment combined use road can be considered for cutting down on expenses of construction sites for a road construction. However, the pre-examination of stability due to the construction should be carried out because it decreases the factor of safety of an embankment. From this study, it has been found that the factor of safety was dropped most when the water level rose in the transient flow. The result indicates that the stability analysis of a river embankment where the water level changes frequently should be carried out in the condition of transient flow. It is recommended that the inner side of an embankment should have a slope of 1:2 which is identical with the slope of the existing embankment. In addition, the factor of safety also can be decreased due to the traffic loads, and therefore, the effect should also be considered after the construction of embankment combined used road limiting the traffic loads.

• Korean Journal of Construction Engineering and Management
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• v.19 no.3
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• pp.52-60
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• 2018

Korea's public construction projects are under construction through bidding, however, due to the nature of the bidding, collusion between participants can occur. The collusion of bids accordingly damages the client. So, it is necessary to calculate the appropriate fictitious competition price to compensate for this. In this regard, econometrics methods are generally used, but there are limitations and issues arising from the nature of construction, especially design-build bid. Therefore, this study proposes a method to estimate reasonable competitive bid-price in design-build bid. It derives the lowest bid-price from the design submitted by the proponent and estimates the competitive bid-price by examining the factors according to the penetration rate according to the technical level of the tester, the skill level of the competitor, and the type of tester. Based on the method proposed in this study, a reasonable price can be derived that reflects the characteristics of the design and construction bidding bidder selection method and also it can be used as a reference material in the actual bidding process as well as calculating the damage due to the answer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1118-1125
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• 2014

The past IMF foreign exchange crisis and subprime financial crisis had a big influence on variability of macroeconomics, even if the origin of its occurrence might be different. This not only had a significant infrequence on the overall industries, but also produced many insolvent companies by being closely linked with a management environment of an individual construction company leading the construction industry. The purpose of this research is to investigate characteristics of management condition of construction company according to the size of construction company using KMV model developed on the basis of the Black & Scholes option pricing theory. This research has set 28 construction companies listed to KOSPI/KOSDAQ for applying the KMV model and measuring the level of the default risk of construction companies. The data was retrieved from TS2000 established by Korea Listed Companies Association (KLCA), Statistics Korea. The analysis period is between first quarter of 2004 and fourth quarter of 2010. This research examine characteristics of the level and fluctuation process of the management condition of construction company according to the size of construction company.

• Journal of Construction Engineering and Project Management
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• v.8 no.4
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• pp.1-24
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• 2018

In the last decade, the use of Building Information Modeling (BIM) as a new technology has been applied with traditional Computer-aided design implementations in an increasing number of architecture, engineering, and construction projects and applications. Its employment alongside construction management, can be a valuable tool in helping move these activities and projects forward in a more efficient and time-effective manner. The traditional stakeholders, i.e., Owner, A/E and the Contractor are involved in this BIM system that is used in almost every activity of construction projects, such as design, cost estimate and scheduling. This article extracts major features of the application of BIM from perspective of participating BIM components, along with the different phrases, and applies to them a logistic analysis using a fuzzy performance tree, quantifying these phrases to judge the effectiveness of the BIM techniques employed. That is to say, these fuzzy performance trees with fuzzy logic concepts can properly translate the linguistic rating into numeric expressions, and are thus employed in evaluating the influence of BIM applications as a mathematical process. The rotational fuzzy models are used to represent the membership functions of the performance values and their corresponding weights. Illustrations of the use of this fuzzy BIM performance tree are presented in the study for the uninitiated users. The results of these processes are an evaluation of BIM project performance as highly positive. The quantification of the performance ratings for the individual factors is a significant contributor to this assessment, capable of parsing vernacular language into numerical data for a more accurate and precise use in performance analysis. It is hoped that fuzzy performance trees and fuzzy set analysis can be used as a tool for the quality and risk analysis for other construction techniques in the future. Baldwin's rotational models are used to represent the membership functions of the fuzzy sets. Three scenarios are presented using fuzzy MEAN, AND and OR gates from the lowest to intermediate levels of the tree, and fuzzy SUM gate to relate the intermediate level to the top component of the tree, i.e., BIM application final performance. The use of fuzzy MEAN for lower levels and fuzzy SUM gates to reach the top level suggests the most realistic and accurate results. The methodology (fuzzy performance tree) described in this paper is appropriate to implement in today's construction industry when limited objective data is presented and it is heavily relied on experts' subjective judgment.

• Journal of the Society of Disaster Information
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• v.18 no.4
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• pp.817-827
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• 2022

The real-name safety management system is to indicate "safety" after inspection by construction personnel before workers use it for the purpose of preventing safety accidents caused by unsafe conditions in temporary facilities and temporary constructions installed at construction sites. Purpose: By implementing the real-name system for safety management at construction sites, the objective is to respond to the "Severe Accident Punishment Act" and to improve the level of safety management at the same time. Method: In this study, a hierarchical analysis model was produced through previous studies of actual conditions such as types of safety incidents and causality at construction sites. The AHP model was used to calculate integrated weights and rankings with a pairwise comparison questionnaire for experts. Conclusion: As a result of the analysis of the upper classes, construction machinery was evaluated the highest, and real-name management system was evaluated the lowest. As a result of the lower-level analysis, it was considered that opening doors for safety facility management, tower cranes for construction equipment, management under the "Occupational Safety and Health Act" under the real-name management system, and CEO duties for safety management organizations were the most important.

• Journal of Korean Society of Steel Construction
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• v.22 no.1
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• pp.55-65
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• 2010

To effectively secure and execute the national budget, it is very important to estimate the reasonable construction cost of each process in the construction of public facilities and works. The construction cost is generally estimated at the time when the design of the targeted structures has been completed. Without detailed sectional drawings and with only simple information on bridge structures in the planning stage or in the early design stage. it would be very difficult to predict the approximate construction cost. In this study, a more efficient and appropriate approximate construction cost estimation model in the planning stage and in the early design stage is presented and verified as reliable by analyzing the construction cost data of 61 existing steel box girder bridges from previous studies. The results of this study show that when the construction cost that was predicted using the construction cost estimation model in the design stage was compared with the cost from the conventional standards, the suggested model in this study produced results with a very high confidence level.

• Korean Journal of Construction Engineering and Management
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• v.15 no.6
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• pp.3-15
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• 2014

Ever expanding overseas construction is one of the most important issues for Korean construction companies. Among these issues, strategies for overseas plant construction have widely been discussed, because the plant construction has features of low competitiveness and high ripple effects when compared with other construction sectors. In this sense, the purpose of this research is to evaluate the CM capability of Korean construction industry for overseas plant construction. Fourteen construction business functions and four techniques were defined first. Based on these functions and techniques, CM capability was quantified for As-Is (2013), To-Be (2018) and Gap analyses. Findings of this research reveal that 1) capability for construction is quite competent, 2) capabilities for planning, design management, contracting, and risk management are found to be relatively low, where higher value can be added. In addition, it is found that R&D needs to be extended to develop systemized management techniques. It is also required to secure specialists and original technologies at national industrial level.

• Korean Journal of Construction Engineering and Management
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• v.8 no.6
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• pp.188-196
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• 2007

Because the construction is becoming bigger and the construction environment is rapidly changing, IT/IS(Information Technology and Information System) of the construction is recently suggested with the alternative proposal. So not only is a study progressed in the area of the BIM(Buidilng Information Modeling), VC(Virtual Construction) and CIC (Computer-Integrated Construction) but also of the information database of the construction for building the information infrastructure of the construction in the domestic construction. Because object-oriented 3D CAD improves the efficiency of a design work and includes the object information which can use with the base of the information database of the construction, it has the high value not only in the design level but also in the construction life cycle. But compared with the effect, the use of 3D CAD is sluggish in the construction. In this study, after surveying about lowly using 3D CAD on the point of AEC (Architect-Engineer-Contract), the result is analyzed with AHP(Analytic Hierarchy Process). So the aim of this study is to offer the base to find the solution of the Affecting factors about lowly using 3D CAD.