• Journal of Korean Institute of Industrial Engineers
• /
• v.21 no.4
• /
• pp.593-608
• /
• 1995

In this study two issues are considered, one is to develop a pneumatic servomechanism using a direct-connected circuit between inlet and outlet, the other is to design two kinds of advanced controllers such as fuzzy and PID controllers for a fingering system. Besides, the application of the advanced controllers to the newly proposed servomechanism is presented. The procedure of this study is composed of following 6 steps : [Step 1] Structuring of a control system; [Step 2] Development of a pneumatic circuit for the servomechanism ; [Step 3] Characteristic analysis of the valve and cylinder systems ; [Step 4] Determination of optimal parameters of the PID controller ; [Step 5] Design of a fuzzy controller and parameter tuning; and, [Step 6] Experimental analysis of fuzzy and PID controllers. Experimental results show that the newly proposed pneumatic servomechanism has good performance and, not only the performance of the fuzzy controller is better than that of the PID controller but also the fuzzy controller fits well to the control of the pneumatic servomechanism.

• Nuclear Engineering and Technology
• /
• v.55 no.9
• /
• pp.3301-3312
• /
• 2023

This study incorporates a high-fidelity transient analysis solver based on multigroup CMFD in the MOC code STREAM. Transport modeling with heterogeneous geometries of the reactor core increases computational cost in terms of memory and time, whereas the multigroup CMFD reduces the computational cost. The reactor condition does not change at every time step, which is a vital point for the utilization of CMFD. CMFD correction factors are updated from the transport solution whenever the reactor core condition changes, and the simulation continues until the end. The transport solution is adjusted once CMFD achieves the solution. The flux-weighted method is used for rod decusping to update the partially inserted control rod cell material, which maintains the solution's stability. A smaller time-step size is needed to obtain an accurate solution, which increases the computational cost. The adaptive step-size control algorithm is robust for controlling the time step size. This algorithm is based on local errors and has the potential capability to accept or reject the solution. Several numerical problems are selected to analyze the performance and numerical accuracy of parallel computing, rod decusping, and adaptive time step control. Lastly, a typical pressurized LWR was chosen to study the rod-ejection accident.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.722-729
• /
• 2007

The methodology for maintenance system development should overall be considered with all of task characteristic, schedule, and the technical condition of investment sources. This research applies Waterfall model to methodology for the development and construction of maintenance system through customizing the CD (Custom Development) procedure of "HSDM (Hyundai System Development Methodology)" based on information engineering. The waterfall model called as classic life cycle paradigm is defined for the sequent development procedure, which make progress a next step after that a previous step is admitted with thorough review. This model which is popular and the oldest paradigm is used for system development by four steps; demands analysis, design, construction, and maintenance. This methodology advances higher abstract step from higher lower step using top-down approach from concept definition to construction, which notices the end of a step whenever a step is over. Therefore, each step is exactly divided, and consequently the output is clearly yielded.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.45 no.4
• /
• pp.568-573
• /
• 1996

The amorphous silicon films deposited by low pressure chemical vapor deposition are crystallized by the various annealing techniques including low-temperature furnace annealing and two-step annealing. Two-step annealing is the combination of furnace annealing at 600 [.deg. C] for 24 h and the sequential furnace annealing at 950 [.deg. C] 1h or the excimer laser annealing. It s found that two-step annealings reduce the in-grain defects significantly without changing the grain boundary structure. The performance of the poly-Si thin film transistors (TFTs) produced by employing the tow-step annealing has been improved significantly compared with those of one-step annealing. (author). 13 refs., 6 figs., 1 tab.

• Journal of Information Management
• /
• v.28 no.1
• /
• pp.34-61
• /
• 1997

This study suggests that the model of electronic document delivery service be carried out by academic libraries step by step, based on the analysis of the domestic and foreign status. The model consists of the user's request step, electronic document building step, electronic document transferring step. Academic libraries should perform the electronic document delivery service step by step that satisfies user's information need.

• Bulletin of the Korean Chemical Society
• /
• v.21 no.4
• /
• pp.419-424
• /
• 2000

In this study we have investigated the determination of proper time step in molecular dynamics simulation.Since the molecular dynamics is mathematically related to nonlinear dynamics, the analysis of eigenvalues isused to explain the relationship between the time step and dynamics. The tracings of H2 and CO2 molecular dynamics simulation agrees very well with the analytical solutions. For H2, the time step less than 1.823 fs pro-vides stable dynamics. ForCO2, 3.808 fs might be the maximum time step for proper molecular dynamics. Al-though this results were derived for most simple cases of hydrogen and carbon dioxide, we could quantitatively explain why improperly large time step destroyed the molecular dynamics. From this study we could set the guide line of the proper time step for stable dynamics simulation in molecular modeling software.

• Journal of KIISE:Software and Applications
• /
• v.31 no.11
• /
• pp.1455-1473
• /
• 2004

This paper suggests a technique, TELOR(Technique of Object Extraction Based on Legacy System Interface for Improvement of Object Reusability) for reuse and reengineering by analyzing the Legacy System interface to distill the meaningful information from them and disassemble them into object units which are to be integrated into the next generation systems. The TELOR method consists of a 4 steps procedure: 1) the interface use case analysis step, 2) the interface object dividing step, 3) the object structure modeling step, and 4) the object model integration step. In step 1, the interface structure and information about the interaction between the user and the Legacy System are obtained. In step 2, the interface information is divided into semantic fields. In step 3, studies and models the structural and collaborative relationship among interface objects. Finally, in step 4, object model integration step, integrates the models and improves the integrated model at a higher level. The objects integration model created through TELOR provides a more efficient understanding of the Legacy System and how to apply it to next generation systems.

• Journal of Engineering Education Research
• /
• v.9 no.3
• /
• pp.22-36
• /
• 2006

This paper is aimed to design for qualification structure and criteria for preparation of qualification test of computer operation engineer. In this study, a DACUM(Development A curriculum) method job analysis to extract contents such as task range, grades or ranks, eligibility, examination standards, selection criteria of examination questions, examination methods, etc was done by an job analysis committee composed of 7 specialists in the industry and academia. In the first place, this report presents job analysis models by procedures for developing selection criteria of examination questions of computer operation engineer. The first step is preparation for job analysis(data research, interviews and selection of experts), the second step the establishment of job models(first expert council and site study), the third step the drawn-out of knowledge, skills, and tools(the second expert council and site study), the fourth step the selection of courses and subjects(the third expert council), the fifth step the establishment of guidelines for making questions(the third site study).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.16 no.5
• /
• pp.14-21
• /
• 2002

This paper did the study target for modeling, characteristics analysis and harmonic reduce with the detent torque of a 4 phase and 5 phase hybrid type step motor. For this, it was attempted to derive the mathematical modeling and used the permeance method for flux field analysis. Through this analysis result, this paper acquired the detent torque of this model. To compare the characteristics analysis of phase difference with two motors structure it have obtained to derive the operating detent torque with this model. Here, 5 phase motor has known the harmonic reduce of detail torque compare with 4 phase motor. Also, that has showed to improved the step response. The analysis result has represent the effect that a fundamental component of the permeance distribution produces the average torque and that harmonic components produce the ripple torque.

• Journal of the Korean Applied Science and Technology
• /
• v.28 no.1
• /
• pp.6-9
• /
• 2011

Step feed process was analyzed stoichiometrically for the optimal operation conditions in this study. In case of optimal operation conditions, minimum R (sludge recycling) value, r (internal recycling ratio) value, and n (influent allocation ratio) value for the step feed process to acquire the maximum TN removal efficiency were identified by theoretical analysis. Maximum TN removal efficiency, based on stoichiometric reaction, can be obtained by controlling n value for the step feed process.