• Journal of the Korea Institute of Building Construction
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• v.11 no.1
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• pp.9-17
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• 2011

Project delay is one of the most crucial impact factors in the construction process from a schedule and cost management perspective. This study focused on analyzing the causes of concrete frame work delay in the apartment construction project. According to the analysis of project cost composition, the direct cost of concrete works was highest in most samples. Actual delays of concrete works were analyzed for the six different construction components. Causes of delay were grouped into two categories; preconstruction and construction phases and these two groups were further divided into sub-groups. Analysis results revealed that the most significant delay was occurred in the 1st. floor concrete skeleton work. For each delay factor, implications of delay as well as suggestion(s) for reducing the possibility of schedule delay are provided.

• Journal of the Korea Institute of Building Construction
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• v.14 no.4
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• pp.322-328
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• 2014

In this study, revelation performance of concrete at early age according to types of cement, water reducing ratio of high performance superplasticizer and mixing of accelerator for early hydration was examined aiming for reduction of construction period of framework through securing strength at early age of concrete. It was observed that strength at early age, 5MPa in 12hours, 14MPa in 18hours, is secured by early strength improvement type cement and using promotion admixture for early hydration which are Sodium persulfate, Potassium hydroxide. Therefore cost reduction is expected to be possible in construction site by reducing construction period of frame work.

• Land and Housing Review
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• v.3 no.4
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• pp.415-421
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• 2012

In case of Korean housing complex, there became more mixed arrangement of buildings with different number of layers for a variety of urban skyline, recently. For example, around 33% of the construction sites of 'A' public corporation have gaps of more than 4 layers between high-rise buildings and low-rise ones in the same site, according to the survey. Generally, construction duration of the housing complex is estimated based on the layers of the highest building. Due to this baseline, whole construction duration could be extended so that the project cost could be increased. Therefore, framework duration of higher-rise buildings should be reduced to secure the feasibility of the project. On the other hands, these shortenings could adversely harm the feasibility in some cases because there are a wide range of combinations of the buildings with different number of layers in designing housing complex. Therefore, this study shows the results of analysis on effects of framework time shortening on the cost in housing complex project. Moreover, this could set the baseline of checking possibilities in condensing the construction duration of projects with buildings of different layers by supplying comprehensive database.

• Land and Housing Review
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• v.4 no.2
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• pp.193-200
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• 2013

Construction duration in construction project is an important factor which affects project cost. Advanced countries have reduced project cost by time shortening. Even though domestic construction companies have tried to time shortening, they yet failed to find systematic method for time shortening. Typically, duration of structural framework is affected by stripping time of form. Therefore, it need to shorten the stripping time of form for time shortening of structural framework. In this study, specimens of high-early-strength concrete were manufactured with variety conditions and compressive strength was tested. This study proposed stripping time of side and slab forms using test results. The stripping time of form was shortened when using high-early-strength concrete in structural framework by the test results. The result of this study will be useful for time shortening of structural framework.

• Construction Engineering and Management
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• v.8 no.3
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• pp.3-5
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• 2007

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.368-372
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• 2007

Recently, construction companies prefer to use large scale system forms to prepare for lacking of skilled workers, aging and the chances of application of pre-build&post-sale policy. In result of the effort and interest, the duration for framework of domestic high rise buildings has been accomplished to 3-4days per floor but for the apartment housing which form over 90% of the domestic construction industry, and especially the middle story RC apartments which is the main part, the duration for framework is only about 6-8days per level. This is only about 50% of the duration per level of RC residential buildings in North America. In previous researches elementary technology, which has potential of duration reduction, was proposed and this research suggest the applicability in construction sites and ways to improve it using elementary technology applied Mock-up Test. Furthermore, we analyze the productivity and T/C usage rate of the 6day-Cycle and suggest an improved model.

• Korean Journal of Construction Engineering and Management
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• v.5 no.4 s.20
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• pp.87-96
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• 2004

The construction duration in apartment construction is an important factor which affects project cost. Henceforth, the time shortening is essential to retrench project cost and project risk when there adopt Five-Day Workweek and introduce apartment sales after completion of construction. Therefore, the purpose of this study is to examine closely the affecting factors on the duration of framework which forms about $40\sim50\$ percent of total time in apartment construction by analyzing the schedule mechanism of typical floor and to show the reasonable time shortening methods by case study. The shown schedule mechanism and basic schedule table can utilize as a guideline in case of scheduling of framework in the existing construction method. Also, the shown time shortening methods by three case studies will guide the direction and process of time shortening while there need time shortening in many-sided projects.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.6
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• pp.101-109
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• 2019

The purpose of this study is to improve a general Top-Down construction process for superstructure construction period reduction. In a general Top-Down construction sequence, the ground floor slab is set up first. Subsequently, 1st basement level construction including core walls is constructed. Initiation of the ground level superstructure gets waited until then. In this study, removable deck plate installation on the bottom of the core walls of ground level is preceding the concrete casting, therefore, ground level superstructure construction is able to get started earlier. Up to first typical floor concrete casting, total of seventy-two working(calendar) days will be resulted in a reduction from the total construction periods.

• Magazine of the Korea Concrete Institute
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• v.12 no.6
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• pp.109-116
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• 2000

• Korean Journal of Construction Engineering and Management
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• v.5 no.6 s.22
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• pp.170-178
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• 2004

Public construction companies have strictly followed a rule that they should not work in the wet area such as structural frame for a certain period during the winter season. It is usually known that the non-working period during the winter causes increase of the project duration, and the project cost escalation. Also, it makes negative effects on national economy because it reduces workers income. Therefore, the site work for the structural frame should be performed even during the whiter season. But the site work for the structural frame during that period cannot proceeds in the same way as during other periods, and requires a different method for estimating project duration. Through an analysis of time scheduling mechanism, actual working days are obtained for 1 cycle of typical floors in the structural frame during these periods, and non-working days of 5 years average are calculated based on calendar day using data of 5 years weather forecasts for that season. This study proposes an optimized way of estimating project duration for 1 cycle of typical floors in the structural frame during these periods. This estimating method uses the combined actual working days and non-working days of 5 years' average, and the estimated results are confirmed by being compared with field data. This study is expected to be used in estimating the construction duration of the structural frame during the winter season.