• Journal of Energy Engineering
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• v.11 no.3
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• pp.194-202
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• 2002

In this paper, we simulate the power system transient stability of Kwang Yang steel works using object-oriented programming (OOP). OOP is a more flexible method than procedural programming. There are several advantages in dynamic system simulation using OOP, The maintenance and repair of program are easy because it is sufficient to modify necessary parts which correspond to the change of system without overall change of program. We have implemented a graphical man-machine interface (MMI) that can be used draw one-line system diagram and analyze power flow and dynamic stability. The implemented MMI also provide a graphical viewer that display dynamic stability analysis results by mouse event handling. The proposed method have been applied to Kwang Yang steel works network for on-line dynamic stability analysis. The dynamic behaviour of 17 synchronous generators and 25 synchronous motors has been studied in the Kwang Yang network.

• Journal of the Korean Institute of Gas
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• v.11 no.1 s.34
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• pp.18-22
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• 2007

The fault current through the earth originated from a power line ground fault might cause arcing through the soil to an adjacent pipeline, which might bring about not only a catastrophic accident such as gas explosion and oil leakage but also a hazard to the safety of workers responsible for the maintenance and repair of the pipeline. In this paper we investigated the arcing phenomena through soil between a power line tower and a pipeline and outlined the standards for the separation distance of a buried pipeline adjacent to the power line tower.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.8 s.227
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• pp.1221-1228
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• 2004

The vertical roller mill is the important machine grinding and mixing various crude materials in the manufacturing process of portland cement. Table liner is one of grinding elements of vertical roller mill and is subjected to the cyclic bending stress by rollers load and the centrifugal force by rotation of table. It demands $4{\times}10^7$ cycle but has $4{\times}10^6{\sim}8{\times}10^6$ cycle. It fractures at the edge of grinding path of outside roller. The repair expense for it amounts to $30\%$ of total maintenance of vertical roller mill. Therefore, this study shows the fracture mechanism of table liner for vertical roller mill using HDM and fatigue analysis and makes the estimation for safety of vertical roller mill.

• Journal of the Korea Society of Computer and Information
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• v.19 no.5
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• pp.53-60
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• 2014

With the rapid development of IT technology, recently, the development of IT convergence technology related to the facility diagnosis is prevalent, and the study for the efficient integrated management scheme is required to handle all relevant information, from the design to the maintenance, including the stage of repair. In this paper, an efficient scheme to process the complex data for the facility and its diagnosis is proposed based on IT convergence technique and the real-time complex data management is designed. In order to evaluate the performance of the proposed system, the real-time management system is designed for a particular facility, and the comparative results show the good performance of the proposed system.

• Journal of Broadcast Engineering
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• v.27 no.2
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• pp.240-243
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• 2022

Tracking the location of program defects is an essential task for software maintenance and repair. When a bug report is submitted, bug localization is a costly task because of the developer's manual effort. Many researchers have tried to automate the task, but according to the reported results, the performance is still insufficient in practice. Therefore, in this study, we analyzed a large amount of bug report data and the latest research and found that the existing studies used only one preprocessing without considering the characteristics of the bug report. In this paper, to solve the problems mentioned earlier, we propose a pre/post-processing operator selection approach for bug localization.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.40-45
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• 2017

Chemical accidents generated during maintenance, repair, and normal operation, such as dispersion, fire, and explosions, can cause massive losses like a 2012 hydro fluorine leak in Gumi, South Korea. Since this accident, many researches have studied physical mitigation systems. However, due to many difficulties including potential costs and lack time, it is really hard for many companies to install mitigation systems without prior knowledge. Thus, the efficacy of mitigation system should be evaluated. This study assesses a dike design considering the fluid velocity at an open hole when a leakage accident occurs. It is assumed that leakage materials follow a free fall motion. Throughout case studies, a current KOSHA guide for a dike design was evaluated and new guidelines handling various conditions were proposed.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.2
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• pp.203-217
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• 2009

The researches on the development of composite material propeller with outstanding damping effects have been actively attempted for the reduction of radiation noise of underwater vehicle propeller. Composite material suitable for the flexible propeller has the following advantages, such as high specific strength and specific stiffness, low thermal expansion coefficient, high resistance against environmental deterioration, low possibility of corrosion due to cavitation, nonoccurrence of rapid fracture due to fatigue, easy molding of complicated shape, easy repair maintenance and low production costs, etc. For the confirmation of optimal fiber array structures of composite material for the production of the flexible propeller blades, in this study, mechanical characteristics of its specimens according to materials were obtained and structural characteristics of propeller blade were also examined according to materials and stacking fiber arrays.

• Journal of Electrical Engineering and Technology
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• v.7 no.5
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• pp.772-777
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• 2012

Accidents caused by water absorption in water-cooled generator stator windings often occur all over the world. The absorption into the insulator of the coolant, which is used to cool down the heat generated by stator windings during operation, leads to the deterioration of dielectric strength, and insulation breakdown. An insulation breakdown may cause not only an enormous economic loss but also a very serious grid accident that would compromise stable supply of electric power. More than 50 % of domestic generators have been in operation for more than 15 years, and water absorption tests performed on 50 water-cooled generator stator windings during a five-year planned preventive maintenance period beginning in 2006 identified water absorption problems in 10 of them, all of which required repair. Because the existing water absorption test detects this problem by utilizing stochastic methods after measuring the capacitances at the final positions of insulation breakdown, its accuracy is limited. This study demonstrates that water absorption can be more accurately diagnosed by utilizing method along with a more precise one.

• Journal of the Korea Society of Computer and Information
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• v.21 no.10
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• pp.115-123
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• 2016

In this paper, we propose a Model Driven Development using UML(Unified Modeling Language) in an efficient Combat System Software development methods. UML is managed by the OMG (Object Management Group) as a Unified Modeling Language. Recently, In developing the software for the system, development time is contrary to a short, while it must meet a number of requirements of our customers. If you develop a non-efficient software early, the structure of the software become more complex in proportion to the number of requirements. As a result, a serious problem in the system, such as an increase in defective products due to the lowering of the reliability and communication problems between the developer has occurred. To overcome those problems, the aim of this paper is to develop a reusable high efficient Combat System Software by applying Model-Centric Development (Not Code-Centric Development). If Combat System Software development method using the UML proposed in this paper is used, easy communication among developers can help reduce the serious errors in systems. Also, it has the advantage that the future needs of software maintenance/repair become easy by using high readability object Model.

• Journal of Korean Society of Rural Planning
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• v.22 no.2
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• pp.19-29
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• 2016

Disasters that occur most frequently in rural areas are drought, flood, damages from wind and cold weather. Among these, damages from storm and flood and drought are the main disasters and recently, these are occurring on a large scale due to unusual weather conditions. Under such circumstances, projects and researches on disasters in rural areas are under way but they are mostly targeting one area or making approaches focusing on repair facilities, maintenance project of facilities in small streams, and disaster management, so there have not been enough studies on the current status of overall damaged facilities in the rural areas. Against this backdrop, through the analysis of the current status of damaged facilities due to storm and flood in rural areas, this study aims to provide base data for policies needed for disaster recovery planning and maintenance work of rural areas. For the analysis of damaged facilities due to storm and flood in rural areas, using the annual report on disasters issued by Ministry of Public Safety and Security and based on the occurrence rate of estimated damage in each city and district for the past 10 years(2004~2013), 8 areas with the highest number of occurrence and cost of damage were found from each province and target areas were selected. Then, regarding the selected target areas, the General Plan for Reducing Damages from Storm and Flood, which is the report on top-level plan for preventing disasters, was secured and the current status of damaged facilities were analyzed. After organizing the analysis of current status, the tendency of damaged facilities due to storm and flood in rural areas, the items of damaged facilities depending on the types of storm and flood damages, and risk factors were suggested. Based on this result, in order to generalize the results of follow-up researches, it is thought that disaster recovery planning and establishing the system of remodeling items necessary for maintenance work would be possible by analyzing damage investigation items recorded in additional researches on rural areas, researches on natural disasters, and recovery plan instructions and by conducting on-site investigation on the damaged villages from storm and flood in rural areas.