• Journal of the Korean Society of Systems Engineering
• /
• v.16 no.2
• /
• pp.38-46
• /
• 2020

The accurate measurement of critical heat flux (CHF) in flow boiling is important for the safety requirement of the nuclear power plant to prevent sharp degradation of the convective heat transfer between the surface of the fuel rod cladding and the reactor coolant. In this paper, a System Engineering approach is used to develop a model that predicts the CHF using machine learning. The model is built using artificial neural network (ANN). The model is then trained, tested and validated using pre-existing database for different flow conditions. The Talos library is used to tune the model by optimizing the hyper parameters and selecting the best network architecture. Once developed, the ANN model can predict the CHF based solely on a set of input parameters (pressure, mass flux, quality and hydraulic diameter) without resorting to any physics-based model. It is intended to use the developed model to predict the DNBR under a large break loss of coolant accident (LBLOCA) in APR1400. The System Engineering approach proved very helpful in facilitating the planning and management of the current work both efficiently and effectively.

• Earthquakes and Structures
• /
• v.11 no.2
• /
• pp.315-326
• /
• 2016

This paper presents the results of cyclic loading tests on concrete beams reinforced with various reinforcement, including ordinary steel bars, CFRP bars and CFRP prestressed concrete prisms(PCP). The main variable in the test program was the level of prestress and the cross section of PCP. The seismic performance indexes including hysteretic loops, skeleton curve, ductility, energy dissipation capacity and stiffness degradation were analyzed. The results show that the CFRP prestressed concrete prisms as flexural reinforcement of concrete beams has good seismic performance. And the ductility and the energy dissipation capacity were good, the hysteresis loops were full and had large area.

• Computers and Concrete
• /
• v.18 no.3
• /
• pp.355-366
• /
• 2016

This paper reports the testing of concrete slabs reinforced with CFRP prestressed concrete prisms(PCP) on the flexural behavior. Four concrete slabs were tested, a reference slab reinforced with steel bars, and three slabs reinforced with CFRP prestressed concrete prisms (PCP). All slabs were made with dimensions of 600mm in width, 2200mm in length and 150 in depth. All concrete slabs reinforced with CFRP prestressed concrete prisms(PCP) exhibited CFRP bar rupture failure mode. It was shown that the application of the CFRP prestressed prisms can limit service load deflections and crack width, the increased level of prestress in the CFRP prestressed prism positively affected the maximum crack width. The deflection of concrete slabs reinforced with CFRP prestressed prisms decreased as prestress in the CFRP prestressed prism increased.

• Structural Engineering and Mechanics
• /
• v.65 no.3
• /
• pp.343-348
• /
• 2018

This paper reports mechanical behavior of recycled fine aggregate concretes after high temperatures. It is found that compressive strength of recycled fine aggregate concretes decline significantly as the temperature rises. The elastic modulus of recycled fine aggregate concretes decreases with the increase in temperature, and the decrease is much quicker than the decrease in compressive strength. The split tensile strength of recycled fine aggregate concrete decrease as the temperature rises. Through the regression analysis, the relationship of the mechanical behavior with temperature are proposed, including the compressive behavior, elastic modulus and split tensile strength, which are fitting the test data.

• Proceedings of the Korean Reliability Society Conference
• /
• 2000.04a
• /
• pp.231-238
• /
• 2000

The distributed digital control system has many shared common components, and a single fault in the system may have effects on not a single function. Not as in an analog system, the faults in a digital system usually make discrete and abrupt changes in its output, which are hard to be expected. To cope with these situations, the fault-tolerance is an inevitable property of a distributed control system. A distributed digital control system consists of many equipments, and each equipment can be implemented by many different technologies. The fault-tolerance has to be implemented depend-ing on the overall architecture and how each equipment is implemented. The paper analyzes and compares the strategies and tactics to add the fault-tolerances in a distributed digital control system, and studies how they can be combined appropriately.

• Steel and Composite Structures
• /
• v.31 no.2
• /
• pp.125-131
• /
• 2019

This paper presents the results of an experimental study to investigate the mechanical behavior of partially encased composite columns confined by CFRP under axial compression. The results show that the failure of the partially encased composite columns confined by CFRP occurred due to rupture of the CFRP followed by local buckling of the steel flanges. External wrapping of CFRP effectively delayed the local buckling of the steel flanges. The load carrying capacity of the column increased with the application of CFRP sheet. And the enhancement effect of the column was increased with the number of CFRP layer.

• Nuclear Engineering and Technology
• /
• v.28 no.4
• /
• pp.359-365
• /
• 1996

Upgrade of nuclear power plant I&C systems by using digital technology has been implemented to overcome the obsolescence of existing equipment and improve plant availability in many advanced countries. For upgrade of the Plant Protection System(PPS) based on conventional analog technology in the UCN 3&4 and YGN 5&6, French modernized Digital Integrated Protection System(DIPS) with proven technology is reviewed and evaluated for the adaptability into PPS. This paper contains the results of feasibility study for the design of digital PPS using French DIPS technology. Based on the results of evaluations, the system architecture of digital PPS is designed and described.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.05a
• /
• pp.291-296
• /
• 1998

The DAta management and Communication NETworks (DACONET), Which it is designed as a subsystem for Man-Machine Interface System of Korea Advanced LIquid MEtal Reactor(KALIMER MMIS) and advanced design concept is approached, is described. The DACONET has its roles of providing the real-time data transmission and communication paths between MMIS systems, providing the quality data for protection, monitoring and control of KALIMER and logging the static and dynamic behavioral data during KALIMER operation. The DACONET is characterised as the distributed real-time system architecture with high performance, Future direction, in which advanced technology is being continually applied to Man-Machine interface System Development of Nuclear Power Plants, will be considered for designing data management and communication networks of KALIMER MMIS

• Journal of Power Electronics
• /
• v.12 no.5
• /
• pp.731-738
• /
• 2012

A new fluorescent dummy load to replace one of the fluorescent lamps in a dual lamp type rapid-start ballast for halving the lamp power is proposed. Using a circuit composed of a fundamental compensation circuit and a harmonic filter circuit, a new fluorescent dummy load having superior characteristics than a conventional dummy load is developed. The design principle and architecture of the proposed fluorescent dummy load is explained and verified by experiments.

• Proceedings of the Korea Society for Simulation Conference
• /
• 2003.11a
• /
• pp.133-138
• /
• 2003

The latest version of the HLA(High Level Architecture) standard developed by the US Department of Defense was established as an open and internal IEEE 1516 HLA standard in 2000. Commercial applications based on the IEEE 1516 have already developed in the non-defense industry. We participated in several development projects for NTS (Nuclear Training Simulator). Extensive modifications are necessary to make a new and/or upgraded NTS because the previously developed simulation softwares have not two desirable property: reusability and interoperability. We reviewed the IEEE 1516 specifications to develop NTS having the capability of reusability and interoperability. Our review activities were forced on application development process, supporting tools, and software structure of NTS. The primary goal of this review is to identify what are constraints or problems to be resolved when we apply IEEE 1516 to NTS development. In this paper we suggest several recommendations for NTS developers.