• Korean Journal of Construction Engineering and Management
• /
• v.10 no.2
• /
• pp.26-33
• /
• 2009

The required level of detail in scheduling depends on the stages in the construction life-cycle. The objective of this study is to provide a Standardized Schedule Model (SSM) with an aim to facilitate the estimating of construction duration in the planning stage. The SSM modularizes work items; establishes relations between preceding and succeeding activities; and calculates approximate construction duration. The estimated duration of the SSM was compared with the detailed duration from the commercial scheduling tool using actual work activities. The difference showed to be ranged between -3.1% and +15%, which demonstrates that the SSM can be feasibly applied to the approximate estimation of construction duration.

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

• Structural Engineering and Mechanics
• /
• v.54 no.5
• /
• pp.937-953
• /
• 2015

This paper investigates the load model for single footfall trace of human walking. A large amount of single person walking load tests were conducted using the three-dimensional gait analysis system. Based on the experimental data, Fourier series functions were adopted to model single footfall trace in three directions, i.e. along walking direction, direction perpendicular to the walking path and vertical direction. Function parameters such as trace duration time, number of Fourier series orders, dynamic load factors (DLFs) and phase angles were determined from the experimental records. Stochastic models were then suggested by treating walking rates, duration time and DLFs as independent random variables, whose probability density functions were obtained from experimental data. Simulation procedures using the stochastic models are presented with examples. The simulated single footfall traces are similar to the experimental records.

• Proceedings of the Korean Society for Quality Management Conference
• /
• 2006.04a
• /
• pp.14-19
• /
• 2006

This study examined the effect of waiting in a service queue on the evaluation of service quality focused on its overall process, mediators and moderators The conceptual model of this paper integrates key variables derived from previous studies of consumer waiting behavior. Data obtained from actual customers in service queue at a hospital was used to test the theoretical framework. First, results from the path analysis confirm that negative affect and acceptability of the wait function as mediators in the process that the perceived duration of the wait affects customer's evaluation of overall service quality. Second, the analysis of the data, with the use of moderate regression shows that disconfirmation of wait time expectations, transaction importance, stability of wait time and wait environment work as moderate variables for the relationship between perceived duration of wait and negative affect. For the relationship between perceived wait time and acceptability of the wait, on the other hand, only transaction import ante shows a significant effect as a moderator.

• Journal of the Korea Institute of Building Construction
• /
• v.18 no.6
• /
• pp.595-602
• /
• 2018

Network-based scheduling methods can be classified into CPM method and PERT method. In the network scheduling chart, critical path can be estimated by performing the forward calculation and the backward calculation though the paths in the network chart. In PERT method, however, it is unreasonable to simply estimate the critical path by adding the sum of the activity durations in a specific path, since it does not incorporate probabilistic concept of PERT. The critical path of a PERT network can change according to the target period and deviation, and in some cases, the expected time of the critical path may not be the path with longest expected time. Based on this concept, this study proposes a technique to derive the most-likely critical path by comparing the sum of estimated time with the target time. It also proposes a method of systematically deriving all alternate paths for a network of repetitive activities. Case studies demonstrated that the most-likely critical path is not a fixed path and may vary according to the target period and standard deviation. It is expected that the proposed method of project duration forecasting will be useful in construction environment with varying target date situations.

• Journal of Information Technology Services
• /
• v.19 no.2
• /
• pp.37-47
• /
• 2020

A significant proportion of information subjects experience information security breaches, and the number of reports and counseling cases of personal information infringements is increasing. Increased awareness of the importance of information security has raised interest in the personnel in charge of such tasks. However, hiring excellent new workers and preventing turnovers in information security remain unresolved. In this paper, by modeling the job career path of information security workforce as a Markov chain, we analyze the workforce turnover process and long-term turnover trends by information security jobs, and further analyze the number and duration of turnovers required to engage in specific jobs. The results of this study are expected to be a reference to balancing the supply and demand of information security workers for the government and to ensuring efficient management of the workforce for businesses.

• Smart Media Journal
• /
• v.11 no.5
• /
• pp.82-90
• /
• 2022

Along with the growing popularity of 5G technology, providing flexible and personalized network services suitable for requirements of customers has also become a lucrative venture and business key for network service providers. Therefore, dynamic network provisioning is needed to help network service providers. Moreover, increasing user demand for network services meets specific requirements of users, including location, usage duration, and QoS. In this paper, a routing algorithm, which makes routing decisions using Reinforcement Learning (RL) based on the information about link stability, is proposed and called Link Stability aware Reinforcement Learning (LSRL) routing. To evaluate this algorithm, several mininet-based experiments with various network settings were conducted. As a result, it was observed that the proposed method accepts more requests through the evaluation than the past link annotated shorted path algorithm and it was demonstrated that the proposed approach is an appealing solution for dynamic network provisioning routing.

• Journal of Mechanical Science and Technology
• /
• v.17 no.10
• /
• pp.1475-1484
• /
• 2003

The EDM processing characteristics of one of the nickel-based heat resistant alloys, Hastelloy- X, were investigated under the various EDM conditions and analyzed in terms of surface integrity. This alloy is commonly used as a material for the hot gas path component of gas turbines and it is difficult to machine by conventional machining methods. The primary EDM parameter which was varied in this study were the pulse-on time. Since the pulse-on time is one of the main factors that determines the intensity of the electrical discharge energy, it was expected that the machining ratio and the surface integrity of the specimens would be proportionally dependent on the pulse-on duration. However, experimental results showed that MRR (material removal rate) and EWR (electrode wear rate) behaved nonlinearly with respect to the pulse duration, whereas the morphological and metallurgical features showed rather a constant trend of change by the pulse duration. In addition the heat treating process affected the recast layer and HAZ to be recrystallized but softening occurred in recast layer only. A metallurgical evaluation of the microstructure for the altered material zone was also conducted.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.12 no.4
• /
• pp.163-169
• /
• 2016

This study is to analyze factors affecting a growth of online community with perspectives of social network. Particularly this study tries to explore structural phenomenon built by interactions between users in a certain of free board belonging to the online community, in which focuses on one's writing a comments responding on those of others. With using SNA(Social Network Analysis), the social network data calculated from users' interaction shown as their comments were collected to draw out each individual's centrality value representing the structure of the online community and also we estimated duration time and the number of each comments as a proxy variable representing growth of the online community. And then cause-and-effect relationship between individual's centrality value and the duration time and the number of each comment were analyzed. As a result of the analysis, Core-Periphery, Centralization and Reciprocity have significant effects on the duration time and the number of each comment, therefore those significant values representing online structure will give an implication to manage, to promote the online community, to forecast its evolution path and to build critical policies.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2000.10a
• /
• pp.91-97
• /
• 2000

Once a response spectrum is estimated for the site, if there is a need of generating realistic earthquakes time histories considering seismic sources and path effects, one alternative is to use statistical phase characteristics based on real earthquake records other than assuming arbitrary duration and envelope curves. In this study, statistics of group delay times derived from Japanese strong earthquake data were used for phase generation to fully capture the stochastic property of earthquakes. The result shows that simulated earthquake time histories can be generated according to earthquake magnitude and distances with target response spectrum.