• Journal of the Society of Naval Architects of Korea
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• v.53 no.1
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• pp.18-28
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• 2016

In shipbuilding, the scheduling system is susceptible to sudden changes and thus it turns to be difficult to predict the differences between schedule and production records in advance. A computer-based simulation is commonly utilized to overcome the discrepancies occurred in estimating workloads and resulting processing times. The main drawback of this simulation-based solution is its limited applicability because, in most cases, each shipyard requires specific and customized simulation environment. By standardizing the planning data of the midterm scheduling system, as proposed in this paper, the efficiency of the current simulation model can be enhanced. To present an alternative approach, this paper begins with the analysis of the complex planning data structure of several shipyards and then proceeds to construct a standard data structure based on the neutral format. An interface application is developed for the data transaction and simulation in on-line environment. As a result, a simulation-based production management of shipyards can be achieved by the efficient prediction of planning and scheduling.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1072-1079
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• 2014

This paper introduces a coordinated droop control for the stand-alone DC micro-grid, which is composed of photo-voltaic generator, wind power generator, engine generator, and battery storage with SOC (state of charge) management system. The operation of stand-alone DC micro-grid with the coordinated droop control was analyzed with computer simulation. Based on simulation results, a hardware simulator was built and tested to analyze the performance of proposed system. The developed simulation model and hardware simulator can be utilized to design the actual stand-alone DC micro-grid and to analyze its performance. The coordinated droop control can improve the reliability and efficiency of the stand-alone DC micro-grid.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.614-618
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• 2012

Smart grid is widely considered to be a next generation power grid, which will be integrated with information feedback communications.However, smart grid communication technologies are subject to inefficient spectrum allocation problems. Cognitive radio networks can solve the problemof spectrumscarcity by opening the under-utilized licensed bands to secondary users. In this paper, adaptive cognitive radio spectrum sensing and sharing algorithms are developed for smart grid environments. Simulation results are presented to demonstrate the effectiveness of the proposed scheme in comparison with other existing schemes.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.425-432
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• 1996

Integrated performance test of Chemical and Volume Control System (CVCS) was successfully performed in 1994. However, an extensive effort to correct hardware and software problems in the letdown line was required mainly due to the lack of adequate simulation code to predict the test accurately. Although the LTC computer code was used during the YGN 3'||'&'||'4 NSSS design process, the code can not satisfactorily predict the test due to its insufficient letdown line modeling. This study developed a numerical model to simulate the letdown test by modifying the current LTC code, and then verified the model by comparing with the test data. The comparison shows that the modified LTC computer code can predict the transient behavior of letdown system tests very well. Especially, the model was verified to be able to predict the "Stiction" phenomena which caused instantaneous fluctuations in the letdown backpressure and flowrate. Therefore, it is concluded that the modified LTC computer code with the ability of calculating the "Stiction" phenomena wi11 be very useful for future plant desist and test predictions.predictions.

• Proceedings of the Korean System Dynamics Society
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• 2006.04a
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• pp.101-122
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• 2006

A series of system dynamics model was developed for forecasting demand and supply of human resource in the electricity industry. To forecast demand of human resource in the electric power industry, BLS (Bureau of Labor Statistics) methodology was used. To forecast supply of human resource in the electric power industry, forecasting on the population of our country and the number of students in the department of electrical engineering were performed. After performing computer simulation with developed system dynamics model, it is discovered that the shortage of human resource in the electric power industry will be 3,000 persons per year from 2006 to 2015, and more than a double of current budget is required to overcome this shortage of human resource.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.4
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• pp.541-547
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• 2022

Realistic education using virtual reality compared to traditional learning can enhance students' understanding of knowledge through immersion and interaction. In previous studies, VR education is mainly focused on experiences, and it is difficult to find its applications for environmental education. Environmental issues are a global problem, and environmental education is essential for the future. In this research, we developed an immersive virtual reality-based environmental education simulation designed to help students recognize the importance of environmental education and participate in environmental-friendly actions. This simulation is based on the virtual ecosystem model, which maintains a casual relationship among environmental factors, spatio-temporal connection, and persistent state. Users intuitively recognize environmental problems and is motivated to solve the problem while experiencing the results of interaction related to environmental factors in virtual environment.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.36-44
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• 2000

In his study the simulation was carried out by simplifing and modeling dividing into fuel injectioin pump high pressure pipe and fuel injection valve in the fuel injection system of a low speed marine diesel engine. A computer simulation model was developed using the method of characteristics to analyze the unsteady flow in the fuel injection system considering cavitation and variation of fuel density and bulk modulus. Comparison was commenced between the calculated data and experimental data of pressure and injection quantity at the high pressure distributor in fuel injection system for the training ship "M/V hanara" the effects of the high pressure pipe length diameter plunger diameter nozzle openning pressure were also investigated by simulating results.g results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.10
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• pp.2605-2619
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• 1996

In this paper, we evaluated performance of mobile exchange control part. Queueing network model is used for modeling of mobile exchange control part. We developed a call control processing and location registration scenartio which has a message exchange function between processors in mobile exchange control part. A network symbol are used the simulation models that are composed of the initialization module, message generation module, message routing module, message processing module, message generation module, HIPC network processing module, output analysis module. as a result of computer simulation, we obtain the processor utilization, the mean queue length, the mean waiting time of control part based on call processing and location registration capacity. The call processing and location registration capacity is referred by thenumber of call attempts in the mobile exchange and must be satisfied with the quality of service(delay time).

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.1
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• pp.71-80
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• 2004

A new SSN(Simultaneous Switching Noise) model is presented, which can afford to investigate SSN due to integrated circuit package. It is shown that previous SSN models are not accurate enough to be practical since they do not take decoupling capacitor into account. In this paper, a new SSN model including the decoupling capacitor is developed. It is verified that the model has excellent agreement(within $5\%$ error) with HSPICE simulation which employs TSMC 0.18um CMOS process technology.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.205-215
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• 1996

In this paper, the performance analysis of the vehicle with the Ravigneaux type automatic transmission has been carried out using information of engine and drivetrain. It is necessary to understand the overall system including engine, torque converter, clutch, planetary gears, and road load. The equations of motion are derived from dynamic model. The GUI computer simulation program has been developed to analyze the powertrain performance of the vehicle with the Ravigneaux type automatic transmission.