• International conference on construction engineering and project management
• /
• 2009.05a
• /
• pp.1068-1074
• /
• 2009

The progress is widely used as a critical index for successful construction project management. In spite of the importance of progress measurement, the excessive management effort to collect and maintain detailed data has been highlighted as a major barrier to measurement of highly accurate progress. In order to reduce the required workload and to enhance accuracy, several researches have been conducted. These researches can be categorized into two groups. First group focuses on automated data collection utilizing advanced technologies only for limited construction tasks. The second group is a research area where the standard progress measurement methodologies encompassing entire construction tasks are investigated. Topics include the adjusting the level of details, standardizing work processes, and applying flexible WBS. However, the techniques for automated data collection are not fully investigated yet in the second group. Combining these two research areas can provide a solution for more effective progress management in terms of enhancing accuracy and optimizing workload. However, there has been no comprehensive research addressing these two research groups in an integrated manner. In this context, the purpose of this paper is to propose a methodology that identifies the most suitable measurement method and data acquisition technology (e.g., GPS, RFID, etc.) for entire construction tasks of a project. The proposed methodology in this paper will be able to facilitate the selection process of data acquisition technologies for entire construction tasks of a project and to support the overall enhancement of automated progress management.

• Journal of the Korean Society of Combustion
• /
• v.13 no.1
• /
• pp.17-22
• /
• 2008

A partly implicit/quasi-explicit method is introduced for the solution of detailed chemical kinetics with stiff source terms based on the standard fourth-order Runge-Kutta scheme. Present method solves implicitly only the stiff reaction rate equations, whereas the others explicitly. The stiff equations are selected based on the survey of the chemical Jaconian matrix and its Eigenvalues. As an application of the present method constant pressure combustion was analyzed by a detailed mechanism of hydrogen-air combustion with NOx chemistry. The sensitivity analysis reveals that only the 4 species in NOx chemistry has strong stiffness and should be solved implicitly among the 13 species. The implicit solution of the 4 species successfully predicts the entire process with same accuracy and efficiency at half the price.

• Corrosion Science and Technology
• /
• v.2 no.1
• /
• pp.41-46
• /
• 2003

Flow-Accelerated Corrosion behavior concerning both activation and mass transfer process of SA106 Gr.C steel was studied using rotating cylinder electrode in room temperature alkaline solution by DC and AC electrochemical techniques. Passive film was tanned from pH 9.8 by step oxidation of ferrous product into hydroxyl compound. Corrosion potential shifted slightly upward with rotating velocity through the diffusion of cathodic species. Corrosion current density increased with rotating velocity in pH 6.98, while it soon saturated from 1000 rpm at above pH 9.8. On the other hand the limiting current increased with rotating speed regardless of pH values. It seems that activation process, which represents formation of passive film on the bare metal surface, controls the entire corrosion kinetics

• The Journal of the Korea Contents Association
• /
• v.15 no.6
• /
• pp.539-546
• /
• 2015

In this study, we develop numerical model using the elliptic mild-slope equation for waves propagating around axis-symmetric topographies where the water depth varies arbitrarily having zero at the coastline. The entire region is divided into three regions. In the both of inner and outer regions, an existing analytical solutions are used. In the middle region, the finite element technique is applied to the governing equation. To get the solution, the methods of separation of variables, Frobenius series are used. Developed solution is validated by comparing with previously developed analytical solution. We also investigate various cases with different bottom topographies.

• Structural Engineering and Mechanics
• /
• v.15 no.1
• /
• pp.71-81
• /
• 2003

The governing differential equation for buckling of a one-step bar with the effect of shear deformation is established and its exact solution is obtained. Then, the exact solution is used to derive the eigenvalue equation of a multi-step bar. The new exact approach combining the transfer matrix method and the closed form solution of one step bar is presented. The proposed methods is convenient for solving the entire and partial buckling of one-step and multi-step bars with various end conditions, with or without shear deformation effect, subjected to concentrated axial loads. A numerical example is given explaining the proposed procedure and investigating the effect of shear deformation on the critical buckling force of a multi-step bar.

• Nuclear Engineering and Technology
• /
• v.32 no.6
• /
• pp.595-604
• /
• 2000

Flow-Accelerated Corrosion Behavior of SA106 Gr.C steel in room temperature alkaline solution simulating the CANDU primary water condition was studied using Rotating Cylinder Electrode. Systems of RCE were set up and electrochemical parameters were applied at various rotating speeds. Corrosion current density decreased up to pH 10.4 then it increased rapidly at higher pH. This is due to the increasing tendency of cathodic and anodic exchange half-cell current. Corrosion potential shifted slightly upward with rotating velocity. Passive film was formed from pH 9.8 by the mechanism of step oxidation and the subsequent precipitation of ferrous species into hydroxyl compound. Above pH 10.4, the film formation process was active and the film became stable. Corrosion current density showed increment in pH 6.98 with the rotating velocity, while it soon saturated from 1000 rpm above pH 9.8. This seems that activation process which represents formation of passive film on the bare metal surface controls the entire corrosion process

• Journal of Computing Science and Engineering
• /
• v.2 no.3
• /
• pp.249-273
• /
• 2008

Epidemic protocols have two fundamental assumptions. One is the availability of a mechanism that provides each node with a set of log(N) (fanout) nodes to gossip with at each cycle. The other is that the network size N is known to all member nodes. While it may be trivial to support these assumptions in small systems, it is a challenge to realize them in large open dynamic systems, such as peer-to-peer (P2P) systems. Technically, since the most fundamental parameter of epidemic protocols is log(N), without knowing the system size, the protocols will be limited. Further, since the network churn, frequently observed in P2P systems, causes rapid membership changes, providing a different set of log(N) at each cycle is a difficult problem. In order to support the assumptions, the fanout nodes should be selected randomly and uniformly from the entire membership. This paper investigates one possible solution which addresses both problems; providing at each cycle a different set of log(N) nodes selected randomly and uniformly from the entire network under churn, and estimating the dynamic network size in the number of nodes. This solution improves the previously developed distributed algorithm called Shuffle to deal with churn, and utilizes the Shuffle infrastructure to estimate the dynamic network size. The effectiveness of the proposed solution is evaluated by simulation. According to the simulation results, the proposed algorithms successfully handle network churn in providing random log(N0 fanout nodes, and practically and accurately estimate the network size. Overall, this work provides insights in designing epidemic protocols for large scale open dynamic systems, where the protocols behave autonomically.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2306-2309
• /
• 2011

With the opening of 1st phase and 2nd phase in Gyeongbu High Speed Line, KTX(The Korea Train Express) and Sancheon(2nd generation of High Speed Train) are operating commercially on entire line. Gyeongbu High Speed Line can be separated as several sections. In this entire line, a few types of train has operating by it's own pattern. However, commercial speed of the line compared with the maximum speed of Train is rather slow. Through this study, I found the reason of the slow speed on the Catenary system and suggested a solution.

• Journal of Korean Society for Atmospheric Environment
• /
• v.15 no.E
• /
• pp.65-71
• /
• 1999

The log-normal size distribution theories developed recently for aerosol coagulation are reviewed. The analytical solutiosn to Brownian coagulation developed recently for various particle size regimes are reviewed. In order to describe the evolution of the size distribution of a coagulating aerosol over the entire size range, the analytical solutions developed individually for the free-molecule regime, the transition regime, the nearcontinuum regime, and the continuum regime have been combined. The work described here represents the first analytical solution to the aerosol coagulation problem covering the entire particle size range.

• Korean Journal of Materials Research
• /
• v.15 no.1
• /
• pp.47-53
• /
• 2005

The E.M.F. of the galvanic cell with fused salt was measured to determine the activities of zinc at 720-860 K over the entire composition range of liquid Zn-In and Zn-Sn alloys. The cell used was as follows: $$(-)W{\mid}Zn(pure){\mid}Zn^{2+}(KCl-LiCl){\mid}Zn(in\;Zn-In\;or\;Zn-Sn\;alloy){\mid}W(+)$$ The activities of zinc in the alloys showed positive deviation from Raoult's law over the entire composition range. The activity of cadmium and some thermodynamic functions such as Gibbs free energy, enthalpy and entropy were derived from the results by the thermodynamic relationship. The comparison of the results and the literature data was made. The liquid Zn-In and Zn-Sn alloys are found to be close tn the regular solution. The concentration fluctuations in long wavelength limit, $S_{cc}(o)$, in the liquid alloy were calculated from the experimental results.