• Korean Journal of Construction Engineering and Management
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• v.16 no.5
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• pp.54-64
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• 2015

The modular construction has several advantages such as high quality of product, safe work condition and short construction duration. The manufacturing planning of modular construction should consider time frame of manufacturing, transport and erection process with limited resources (e.g., modular units, transporter and workers). The manufacturing planning of multi modular construction project manages the modular construction's characteristics and diversity of projects, as a type of modular unit, modular unit quantities, and date for delivery. However, current modular manufacturing planning techniques are weak in dealing with resource interactions and each project requirement in multi modular construction project environments. Inefficient allocation of resources during multi modular construction project may cause delays and cost overruns to construction operation. In this circumstance, this research suggest a manufacturing planning model for schedule optimization of multi project of modular construction, using genetic algorithm as one of the powerful method for schedule optimization with multiple constrained resources. Comparing to the result of the existed schedule of case study, setting optimized scheduling for multi project decrease the total factory producing schedule. By using proposed optimization tool, efficient allocation of resource and saving project time is expected.

• Korean Journal of Construction Engineering and Management
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• v.16 no.4
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• pp.139-145
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• 2015

Modular construction is combined with manufacturing production process and conventional construction industry technique. Considering characteristic of modular construction production process, manufacturing facilities require indirect costs for utilities, equipment, and overall maintenance, which can affect modular units pricing. However, current modular construction cost classification is inadvertent to reflect the manufacturing overhead costs, because it is generally added as a percentage to sum of labor, material and equipment as it called in single cost pool used. This process is easy to estimate the total construction cost at the project starting points, but it brings on misunderstanding of project profit estimations by "cross subsidization phenomenon". To prevent this situation, in this research aims to provide modular construction overhead cost handling process at the detailed indirect cost calculation for manufacturing stage using Activity-Based Costing as one of the powerful method for overhead costs estimation and allocation. Using this research results, modular construction cost estimators have more detailed cost information of modular units and prevent to misallocate indirect costs. Also, it can be utilized to aid the understanding of the company's profit structure.

• Korean Journal of Construction Engineering and Management
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• v.13 no.6
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• pp.133-142
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• 2012

With the recent changes in building environments such as low-carbon green growth, there have been increasing demands for the new building system that is eco-friendly and can maximize efficiency such as the unit modular system. For the unit modular system, more than 80% of the whole process is carried out in the factory while in the field, mostly unit module assembling and finish work are done. Thus, the quality at the pre-construction stage when design and manufacturing are done determines the quality of the building as a whole. In the country, the unit modular method was first applied in 2003 to school buildings and has gradually expanded afterwards, but due to the lack of examples and related information as well as the small scale of modular manufacturers, its characteristics have not been sufficiently reflected in design, manufacturing and field constructions. This study, as an attempt to improve the design quality of unit modular buildings, points to the problem in manufacturing and field construction, compares and analyzes its causes, and suggests major points to be considered in the early stage of designing the unit modular buildings.

• Korean Journal of Construction Engineering and Management
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• v.12 no.6
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• pp.14-21
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• 2011

A unit modular system is a construction method which installs on site by manufacturing 50%~90% of the whole process in the factory. This method can minimize the process in the site and maximize the operation, which will reduce the duration and improve the overall quality. The recent paradigm of construction is to be sustainable building. Modular system can be regarded as a sustainable building construction method because it can reduce the amount of construction waste by recycling partial or whole part of overdue building be torn down. A unit modular system is the answer to cope with the increasing market of small size housings. A unit modular system is the most appropriate option at this point. This research proposes the standard operation and construction process of modular system, which enable to optimal system. A case study of reconstructing small-size housing was introduced to support this proposal. Finished unit modular is the reasonable way. However, 80% of complication rate of the modular is the most rational when a defect occurrence during delivery is considered.

• Journal of the Korea Institute of Building Construction
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• v.18 no.3
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• pp.277-283
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• 2018

This study is conducted to improve the manufacturing process of the modular construction method, which is a pre-fabricated construction method recognized for its advantage on the shortening of construction time. This study first identified the factors that result in shortening of pre-fabrication processes in the current module-processing factory. In addition, those identified factors were further considered for installing the M.E.P. system that is being outsourced on the main module in the production line. A manufacturing process of the construction modules, which considers installation of a M.E.P. system most suitable for shortening the time on the outsourcing of modular construction, is introduced throughout the research. Furthermore, this study suggests the factors in need of improvement during design phase of modular construction and improvement measures to consider the quality of unit modules by focusing on the module parts that are most exposed to defects.

• Korean Journal of Construction Engineering and Management
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• v.13 no.5
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• pp.103-112
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• 2012

Republic of Korea is recently becoming an advanced country with increasing standard of living. This is causing a lack of employment in the construction industry because of high labor costs and it is resulting rapid increase in foreign labors. Modular Method of Construction can be defined as 50%~90% of the entire process is completed in factory, and transferred to construction field to install. The main purpose of this process is to minimize the entire process that possibly can be done at construction field in order to maximize the quality. The current local usage of Modular Method of Construction started at Shin Ki Elementary School during 2003 and it is widely used for military facilities. It should be used more because it has strengths of spending short time period to complete and low production costs. It can make a change if Modular Method of Construction is applied. Toyota is currently producing vehicle with conveyor system and if Modular Method of Construction is applied, then it is possible to reduce the waste of labor, and automatic production time. Expansion of the modular Market can be expected by applying this method because it will improve producing costs, high quality, and enforced process. This research tried to solve the problem of factory's manufacturing production by applying local Modular Method of Construction to provide suggestions and analyze the profitability with applied conveyor system. It is depending on produced model, but this research's model will take 20 months including assessment of payback period.

• Korean Journal of Construction Engineering and Management
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• v.20 no.3
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• pp.12-21
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• 2019

Specification is an important document for securing safe construction and improving quality as well as the contract document. Currently, the specifications used in modular buildings in Korea are only the construction specification, and most of the contents are used by borrowing the standard specifications of the building, so the contents of the modular buildings can not be reflected and it is contents are similar to the guideline book. The current status of domestic specification for modular buildings is affecting the quality of modular buildings. Therefore, we analyze activity through monitoring the modular process of modular buildings and analyze systematically relationship by applying IDEF modeling with analyzed activity. As result this paper proposes a structure of special specification specialized in modular building through generalization. The major classifications were divided into three stages : factory construction, transportation, and on-site installation. The specification structure was divided into 32 types of construction items from the floor slab assembly of the factory production to the joint finish of the on site installation in accordance with the opinion of experts.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.6
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• pp.139-146
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• 2019

The modular building system is a type of prefabricated construction method, and is an industrialized building system that transports, assembles, and completes a three-dimensional module manufactured in a factory to the site. The economics of a modular building system where 50 to 80% of the entire process takes place in a modular factory is dominated by productivity of the factory manufacturing process. Since the building of the module is finished by the combination of unit parts produced by each material, it is necessary to manage the process in each module unit. However, currently marketed process control programs do not reflect the features of these modular methods. In this paper, we introduce Modular Factory Design software(MFD 2019) that can make modular unit production plan which reflects production base(modular factory) and production target(application and number of modular units). In order to verify software compatibility and reliability, two production plans with different production methods were formulated and simulated.

• Korean Journal of Construction Engineering and Management
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• v.17 no.4
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• pp.49-56
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• 2016

Recent research has been ongoing for modular buildings in the country and interest increases. However, the activation of modular building projects is obstructed in the construction industry. There are many reasons to identity for this obstruction but one issue should be focussed. Modular buildings require to change the existing construction production system to a new construction production system, which is factory production - transportation - erection. However, the existing project delivery system in the public sector could not be adapted for this new construction production system due to the obligation of multi prime contract use, such as electrical, communication, fire fighting contracts by Law. Therefore, modular buildings in the existing project delivery system are separately contracted by multi prime contracts and modular units composed of the buildings are contracted by an architectural prime contractor as a commodity. As results, construction costs are increased, potential quality problems are raised and the existing project delivery system is finally an obstacle not to maximize benefits of the modular buildings. In this paper, we propose a new project delivery system for the modular buildings to adapt then ew construction production system.

• Korean Journal of Construction Engineering and Management
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• v.15 no.5
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• pp.138-146
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• 2014

Modular construction is one of the arising issues in the Korean construction industry due to shorter construction period and higher productivity on site. It is also expected that modular construction market would expand rapidly because of increasing demand of small houses by nuclear families and eco-friendly construction. However modular construction cases have been limited in Korea because of little demand in the market and the construction prices are even higher that the regular reinforced concrete methods. Even worse, because there is no standard bill of services exists in the industry, it may lead to the risk of construction expenses. So, the purpose of this study is focused on the development of bill of services which reflects characteristics and process of modular construction. In order to do this, the concepts and process of modular construction, WBS and CBS are analyzed. Analyses of the case studies and experts interview were executed so that proper principles for organizing bill of service of modular construction is established. Finally according to the 3 steps of modular construction, factory manufacturing, on-site modular construction and on-site general construction, the standard bill of services were suggested with the related coding system.