• Korean Journal of Construction Engineering and Management
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• v.19 no.4
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• pp.61-69
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• 2018

Research on additional indirect cost due to construction period extension in general contracts has continuously been active whereas the same for the subcontract operations has not been. In this research, we review previous research on evaluation methods for additional indirect costs which are widely being used on construction sites as well as previously proposed methods altogether, applying them to analyze model-cases for comparison. We acknowledge that this pattern for construction cost fluctuation over the construction period demonstrates an S-curve. This S-curve shaped indirect cost occurrence is then used to generate model-cases that are used throughout the research which models we applied previous evaluation methods on. Finally in pursuit of finding out some problems of evaluation methods, we came to derive a conclusion that the "Average Actual Cost Evaluation Method on Extended Duration," which, in turn, were proved to be valid for application on general contracts, was also valid for general application on subcontractor operations.

• Tunnel and Underground Space
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• v.15 no.3 s.56
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• pp.177-184
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• 2005

The Sapaesan tunnel, the longest twin tube tunnel (4km) in Korea with 4 lanes each, is under construction with two years of delayed schedule because of the strong opposition from environmental bodies. Therefore, maximizing the construction efficiency was needed in tunnel project to compensate for time delay. This study includes improvements in the construction of the Sapaesan tunnel such as increasing excavation length and changing excavation sequence. In this paper the system for predicting tunnel face ahead is also introduced. Bulk-Emulsion explosive and Cylinder-Cut method were adopted in tunnel blasting to increase the excavation length. Optimum tunnel excavation step was designed to make up delayed time. Tunnel foe mapping, TSP survey and geological prediction system using computerized jumbo-drill were performed fnr safe construction of long and large twin tube tunnel.

• Explosives and Blasting
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• v.39 no.3
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• pp.24-34
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• 2021

Electronic detonators are widely used in various construction sites due to accurate delay time. Including the cases with exceeded noise and vibration from site using electric/non-electric detonator, electronic detonators are used to improve blast fragmentation or to reduce the cost of secondary partial blasting. Furthermore, the number of cases using electronic detonators are increased for reduction of the cost and construction period by maximizing operations efficiency. This case study is about applying electronic detonators on large section station, tunnel construction site which is the part of urban area GTX A project. Although it was initially planned to utilize non-electric detonators, damage was inflicted on safety-thing. We have considered blasting method using electronic detonators as solution of this problem. By applying electronic detonators, we not only satisfied environmental regulations but also prevented nearby safety-thing from getting damaged. In addition, we were able to shorten the construction period than the initial plan by conducting single simultaneous blasting on large section station, in order to ensure safe and efficient construction.

• Journal of Climate Change Research
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• v.7 no.3
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• pp.237-247
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• 2016

Global warming caused by greenhouse gases is one of the foremost challenges in the international community. As an alternative to solve this problem, the importance of CCS (Carbon Capture and Storage) technology is increasing. However, due to the delay of European financial crisis recovery, some large-scale CCS projects were postponed. In turn, large-scale CCS projects in South Korea have not been launched as originally planned. Given these situations, it is important to review the latest R&D activities related to CCS in South Korea, and then adjust relevant national policy accordingly. The purpose of this study is to identify policy issues for the effective promotion of CCS technology in South Korea. Following the analysis of recent global trend on CCS policy, we evaluated the results and achievements from national CCS projects, which had been listed under the "Korean National CCS Master Action Plan (2010)". Especially, we tried to review the attainability for the original goal of each project. Through the present study, we identified the current status of CCS technology in South Korea and suggested efficient ways to be taken in order to increase efficiency in implementing national CCS policy in the future.

• Journal of KIBIM
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• v.10 no.4
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• pp.22-31
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• 2020

Shop drawing tasks conducted after finishing coordinated or engineering design have great influences on the quality and cost of a project. However, despite the development of commercial BIM applications, shop drawings have mainly produced manually in certain engineering fields. Incorrect shop drawings with human errors have occurred various problems such as cost overrun, time delay and reworks. An automated shop drawing publishing from BIM is expected to resolve these problems. Despite attempts for automate shop drawing production, the field of mechanical, electrical and plumbing (MEP) is yet regarded challenging due to complexity of components and connection. In this research, we develop a process for automated producing 3D MEP shop drawings in BIM environment as following steps: to analyze conventional MEP shop drawing process, to identify detailed process that can be automated, to classify existing MEP objects and assign codes usable in BIM, and to develop an application. The validation of automated process is conducted against 10 clean room projects in which MEP is more complex and its cost is higher than other projects in terms of productivity and workers' satisfaction. Results show that the number of manpower for shop drawing is reduced by 30%, and the working time is shortened by 31%. Personal opinions of involved practitioners is interpreted as positive as the average rate of agrement on practicability, easy-to-use and necessary retouch tasks is around 66%.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.472-478
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• 2009

The scopes of the supply chain management in construction projects has expanded from the field management focusing on field storage, transportation, and lifting to the whole supply chain from the materials to field. The expansion of the supply chain management can raise the possibilities of leaner production, which enables shortened lead time of the difficult-to-operate materials, and prevents the work interference or delay. However, the expanded management range requires more information and management than an existing management style currently used for factory production of iron frame, curtain wall, PC, etc. In addition, there are limitations that expand the existing management style into the new supply chain management in construction projects and therefore it is required to automate the existing management style in order to extend the management range. The objective of this study is to propose the process and equipment that can manage the supply chain of the materials which range from the factory production to the field storage based on RFID/USN techniques, introducing small-sized transportation equipment(intelligent pallet), the vehicle tool kit(intelligent trailer), and in-and-out management equipment(Gate Sensor) as a prototype to effectively develop the appliances for operating the proposed process, and present the application possibility of the appliances. The full paper will present then the test results that the proposed appliances for the supply chain management automatically transmit and receive the generated information between the appliances or the appliance and sever under various wireless network circumstances such as zigbee, wibro, Wi-Fi, and CDMA.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.171-186
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• 2010

It is generally known that the mechanism of behavior in the flexible earth retaining system is relatively more complicated than in the rigid earth retaining system. Moreover in the case of long span strut supporting system the analysis of strut axial force change becomes more difficult when the differences of ground condition and excavation work progress on both sides of excavation section are added. When deeper excavation than the specification or installation delay of supporting system or change of ground condition happen during construction process, lots of axial force can be induced in some struts, which threaten the safety of construction. This paper introduces two examples of long span deep excavation where struts and rock bolts were used as a supporting system with flexible wall structure. The characteristics of ground deformation and strut axial force change, which were measured in the sections of two examples that are 50 meters apart in one construction site and have almost similar design and construction conditions were analysed, the similarity and difference between measurement results of two examples were compared and investigated. This article aims to improve and develop the technique of design and construction in future projects having similar ground condition and supporting method.

• International conference on construction engineering and project management
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• 2017.10a
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• pp.146-152
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• 2017

Recently, countries in the South-east Asia are making efforts to enhance the construction industry system and introduce the construction management system. However, it is challenging to apply construction management in site due to lack of technology and professionals for CM. This can result in frequent safety accidents, cost overrun, schedule delay, etc. Therefore, it is necessary to carry out a clear evaluation of the overall situation regarding the level of technology and required competency. The objective of this research is to investigate on which management skills and items for CM are required to improve the construction management skills in South-east Asian construction industry. As a result of the questionnaire, most of the officials selected that the design phase and the construction phase are important works, and the engineers evaluated activities during the bidding phase, the design phase and the construction phase as important works for construction management. However, in most of the results, it was observed that the current competency of Vietnam construction is insufficient compared to the evaluated importance of the skills. This can be explained by the fact that they are not capable of managing construction projects effectively as compared to the importance. The results can help to realize the inadequate aspects of local construction industry, which will be the basis of improvements. Also, it is expected to be supportive to improve construction management in the countries and also provide indicators related to work stage or technology that should be acknowledged when establishing the advancing strategy for Southeast Asian countries in the future.

• International conference on construction engineering and project management
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• 2017.10a
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• pp.8-13
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• 2017

Nuclear power plant (NPP) constructions are large scale projects that are executed for several years, and schedule control utilizing various schedules is a critically important factor. Recently Korea independently developed the Advanced Power Reactor (APR) 1400 and is building nuclear facilities applying this new reactor type. The construction of Shin-Kori NPP (SKN) Unit 3, which adopted the APR1400, was completed and commercial operation has begun, while, SKN 4, Shin-Hanul NPP (SHN) Units 1&2, and SKN 5&6 are currently under construction. Prior to the development of the APR1400, Korea built 24 reactors and accumulated the schedule data of various reactor types which provided the foundation for schedule reduction to be possible. However, as there is no schedule development and review system established based on the standard schedule data (standard activities, durations, etc.) by reactor type, the process for developing the schedule for new builds is low in efficiency consuming much time and manpower. Also all construction data has been accumulated based on schedule activities. But because the connectivity of activities between projects is low, it is difficult to utilize such accumulated data (causes for schedule delay, causes for design changes, etc.) in new build projects. Due to such reasons, issues continue to arise in the process of developing standard schedule activities and a standard schedule for nuclear power plant construction. In order to develop a standard schedule for NPP construction, i) the development of an NPP standard schedule activity list, ii) development of the connection logic of NPP standard schedule activities, iii) development of NPP standard schedule activity resources and duration, and iv) integration of schedule data need to be performed. In this paper, an analysis was made on the coherence of schedule activity descriptions of existing NPPs by applying the probabilistic methodology on activities with low connectivity due to the utilization of the numbering system of four APR1400 reactors (SHN 1&2 and SKN 3&4).This study also describes the method for developing a standard schedule activity list and connectivity measures by extracting same and/or similar schedule activities.

• Korean Journal of Construction Engineering and Management
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• v.13 no.4
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• pp.48-59
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• 2012

Gangform, compared to the traditional forms, is a systemized form which can reduce construction duration and cost by the advantage of using it repeatedly. However, transportation and climbing process of the Gangform is highly dependant on the performance of tower crane. Gangform climbing process takes one day out of six to seven days of a structural work cycle. Tower cranes can not be used in other lifting works when they lift the Gangform during the structural work cycle, causing the delay in the construction project. Numerous efforts and researches have been done in domestic and international industry to solve such limitations of Gangform climbing process. Especially, "A Study on the Development of Automatic Gangform Climbing System for Apartment Housing Construction"has suggested a conceptual model which can climb the Gangform system without a tower crane. In this paper, the technical and economical feasibilities of previously proposed Automatic Gangform climbing system are examined by evaluating its structural stability and lifting load reduction effect.