• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.150-151
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• 2014

A mold of free-form concrete segment can be used only one time. Thus, the construction duration and cost are increased. The materials of the mold such as wood and metal have limitations due to the implementation and reuse. The review of the material of the mold for free-form concrete segment is needed to reduce duration and production cost. Phase change material can be used both to implement free-shape by heating and to produce mold after cooling. After using Phase change material can be re-used to mold by heating. The scope of this study is many kind of phase change materials for molding. The aim of this study is to analyze the phase change materials for production of changable mold for free-form concrete segment. In this study, the paraffin wax that is melted at 64℃ was selected by considering both the energy efficiency and the weather of Korea.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1424-1430
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• 2007

Corrugated structural plate is ductile structural member which has high sectional properties compared with same thickness of plate. Corrugated plate resists the external forces by the combined action of retained soils and structures. Since it is easy to transport and assemblage of in-situ, the duration and cost of construction can be reduced. Corrugated plate structures, therefore, are widely used in culverts, hydro passages and simple bridges. RC culvert with supported by unstable soil layersin railway construction project of pohang${\sim}$samchuk has been replaced by corrugated plate culvert due to the reduction of construction duration and cost, especially the performance of behavior of settlement of ground. The structural analysis, design processes, and the economic advantages of the corrugated plate culvert are studied in this paper.

• Korean Journal of Construction Engineering and Management
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• v.6 no.1 s.23
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• pp.73-79
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• 2005

This paper, introduces a Stochastic Project Scheduling Simulation system (SPSS III) developed by the author to predict a project completion probability in a certain time. The system integrates deterministic CPM, probabilistic PERT, and stochastic Discrete Event Simulation (DES) scheduling methods into one system. It implements automated statistical analysis methods for computing the minimum number of simulation runs, the significance of the difference between independent simulations, and the confidence interval for the mean project duration as well as sensitivity analysis method in What-if analyzer component. The SPSS 111 gives the several benefits to researchers in that it (1) complements PERT and Monte Carlo simulation by using stochastic activity durations via a web based JAVA simulation over the Internet, (2) provides a way to model a project network having different probability distribution functions, (3) implements statistical analyses method which enable to produce a reliable prediction of the probability of completing a project in a specified time, and (4) allows researchers to compare the outcome of CPM, PERT and DES under different variability or skewness in the activity duration data.

• Journal of Korean Association for Spatial Structures
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• v.13 no.2
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• pp.57-66
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• 2013

There are a number of construction methods to build spatial structures such as erection method, Element method, Block method, Sliding method, Lift-up method and Push-up method. These methods are uneconomical and low accuracy, and require long construction duration because of a need of a scaffold or a tower crane to build spatial roof frame. In this study, the construction method to erect a truss structure was proposed as an economical and easy installation method. The proposed method has end hinges of keel truss and winches with horizontal cable. This method makes safe and accurate production and reduces construction duration because trusses are built on the floor or supporter. The goal of this study is to verify the validity of construction method by building scale model using the proposed method.

• Korean Journal of Construction Engineering and Management
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• v.8 no.1 s.35
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• pp.87-95
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• 2007

If construction process operate composing work team by judgment manager's experience, possibility that progress of construction process becomes as inefficient is much. But, If produce optimal proposal of resources allocation, construction cost and duration through simulation at work plan step, work schedule because do quantification efficient operate do on. When plan construction process in this research, resources allocation by change of work team operation change, resources cost loss, total cost, optimal proposal of construction duration tentative plan of numerical formula model that can do simulation propose. Apply and revealed to apartment house framework which horizontal work area of process and vertical work area are composed as is each different construction process to verify proposed numerical formula model. Achieved efficiency than work team's operation results which apply numerical formula model that is presented in this research and enforce simulation is applied in actuality example construction.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2004.11a
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• pp.210-215
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• 2004

In can occur to many problems on progressing step without close scope definition, interrelation definition between activities, resource plan, and schedule plan on planning step. But it have not closely defined performance system on planning step because of many constraints of domestic construction industry. Therefore this paper intends to discuss a method of calculating optimal cost and duration using Linear Programming that solves maximing or minimizing problems among decision making methodology and Monte Carlo Simulation that decreases to probability errors. With outcoms applying Linear programming and Monte Carlo Simulation for calculating optimal cost and duration, follow as : With outcomes applying Monte Carlo Simulation, it could calculate reliable estimator about project duration through removing various constraints. With outcomes applying Linear programming, it could calculate optimal value about project cost through defining various variables and constraints on many activities.

• Journal of the Korean Society of Safety
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• v.17 no.3
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• pp.96-101
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• 2002

The object of risk assesment is to prevent the accident from arising. The main reason for risk assesment of construction work is to determine priority order of improvement plan about risky work. Formwork is a complicated process that determines the total duration of apartment construction, and occupies 10∼15% of total construction expense, and 17% of serious accidents occur during formwork. So, formwork occupies very importment roles in work sites, economical efficiency and safety. We need to identify the work type with a high risk of accidents, and to establish suitable safety counterplan and implement intensive safety management.

• The Journal of Engineering Geology
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• v.24 no.1
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• pp.91-98
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• 2014

This paper aims to calculate the increase in groundwater quantity following groundwater dam construction, and to assess its impact on surface water. In the study area of Osib-cheon, Yeongdeok, we estimated groundwater quantity, groundwater level, and effective porosity, and examined surface water fluctuations with respect to the increased groundwater quantity based on the flow duration. The results reveal that the increased groundwater quantity was at most $91,746m^3$ in the total drainage basin of the groundwater dam, and the reduced groundwater quantity was at most $11,259m^3$ in the lower zone of the groundwater dam. Therefore, the total groundwater resources secured was $80,487m^3$ and the decrease in groundwater quantity was just 12.27% of the amount of increase. There were changes in discharge rate by up to $3.00{\times}10^{-2}m^3/s$, as deduced from an analysis offlow duration as a result of groundwater dam construction. The overall difference between before and after construction of the dam was almost insignificant compared with the previous dam. The present results indicate that dammed groundwater can serve as an alternative water resource with sufficient quantity.

• Journal of Korean Society on Water Environment
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• v.25 no.4
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• pp.573-579
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• 2009

The performance of Rainfall-Runoff Forecasting System (RRFS), the watershed management model for the Geum river basin, is evaluated based on the agreement between the simulated and observed hydrographs and the behavioral characteristics of the flow-duration curves. As a result, the simulated hydrographs are well agreed with the observed ones except high flow discharges. It is inferred that most of the errors in the simulated hydrographs are due to the misestimation of agricultural water use in $2^{nd}$ quarter and the discrepancy of the peak discharges in $3^{rd}$ quarter. It is however judged that RRFS would give the reliable runoff hydrographs from the point of view of continuous model application. And simulated flow-duration curves and flow-duration coefficients are also similar to the observed ones except flood flow region. From the above result it is confirmed that the construction of Yongdam dam improves the state of flow-duration curve at the Gongjoo station.

• Speech Sciences
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• v.10 no.4
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• pp.7-21
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• 2003

Sums-of-Products models were built for segment duration prediction of spoken Korean. An experiment for the modelling was carried out to apply the results to Korean text-to-speech synthesis systems. 670 read sentences were analyzed. trained and tested for the construction of the duration models. Traditional sequential rule systems were extended to simple additive, multiplicative and additive-multiplicative models based on Sums-of-Products modelling. The parameters used in the modelling include the properties of the target segment and its neighbors and the target segment's position in the prosodic structure. Two optimisation strategies were used: the downhill simplex method and the simulated annealing method. The performance of the models was measured by the correlation coefficient and the root mean squared prediction error (RMSE) between actual and predicted duration in the test data. The best performance was obtained when the data was trained and tested by ' additive-multiplicative models. ' The correlation for the vowel duration prediction was 0.69 and the RMSE. 31.80 ms. while the correlation for the consonant duration prediction was 0.54 and the RMSE. 29.02 ms. The results were not good enough to be applied to the real-time text-to-speech systems. Further investigation of feature interactions is required for the better performance of the Sums-of-Products models.