• Nuclear Engineering and Technology
• /
• v.55 no.2
• /
• pp.460-474
• /
• 2023

A simple but accurate mathematical model is crucial for dynamic simulations and controller design of helical coil once-through steam generator (OTSG). This paper presents a three-region movable boundary dynamic model of the helical coil OTSG. Based on the secondary side fluid conditions, the OTSG is divided into subcooled region (two control volumes), two-phase region (two control volumes) and superheated region (three control volumes) with movable boiling boundaries between each region. The nonlinear dynamic model is derived based on mass, energy and momentum conservation equations. And the linear model is obtained by using the transfer function and state space transformation, which is a 37-order model of five input and three output. Validations are made under full-power steady-state condition and four transient conditions. Results show good agreements among the nonlinear model, linear model and the RELAP5 model, with acceptable errors. This model can be applied to dynamic simulations and controller design of helical coil OTSG with constant primary-side flow rate.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1995.11a
• /
• pp.75-81
• /
• 1995

DYLAM and its related applications are reviewed in detail and found to have many favourable characteristics. Concerning human factor analysis, the study demonstrates that DYLAM methodology represents an appropriate tool to study man-machine behaviour provided that DYLAM is used to model machine behaviour and an appropriate operator interface human factor model is included. A hybrid model which is a synthesis of the DYLAM model, a system thermodynamic simulation model and a neural network predicative model, is implemented and used to analyse dynamically the CANDU pressurizer system.

• Nuclear Engineering and Technology
• /
• v.21 no.4
• /
• pp.267-276
• /
• 1989

A numerical model for nuclide migration through fractured rock media has been developed. Nuclide transport with groundwater in rock fissures and the diffusion of nuclides into rock matrix are considered one-dimensionally . In the safety assessment of the repository for radioactive waste, this one-dimensional model by the finite-difference scheme, which enables us not only to use more realistic boundary conditions but also to model the nonhomogeneous rock medium as the multilayered media, can be used effectively with the analytical mode. The solution by the numerical model will be verified analytically, and then extended to the double-layered rock medium transport model.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2003.09a
• /
• pp.443-446
• /
• 2003

Conventional disturbance rejection methods have to derive the inverse model of a system. However, the inverse model of n nonholonomic system is not unique, because an inverse it changes depending on initial conditions and desired values. A kind of internal model control (IMC) using feedback error learning is discussed for the motion control of nonholonomic mobile robots in this paper, The present method is different from a conventional IMC whose control system consists of an inverse model, a direct model and a filter. The present disturbance rejection method need not use a direct model, where the remaining two elements are composed of the same inverse model based on neural networks.

• Nuclear Engineering and Technology
• /
• v.52 no.4
• /
• pp.708-720
• /
• 2020

Core-wide temperature distribution in sodium-cooled fast reactor plays a key role in its decay heat removal process, however the prediction for temperature distribution is quite complex due to the conjugate heat transfer between the assembly flow and the inter-wrapper flow. Hybrid medium model has been proposed for conjugate heat transfer modeling in the core. The core is modeled with a Realistic modeled inter-wrapper flow and hybrid medium modeled assembly flow. To validate present model, simulations for a three-assembly model were performed with Realistic modeling, traditional porous medium model and hybrid medium model, respectively. The influences of Uniform/Non-Uniform power distribution among assemblies and the Peclet number within the assembly flow have been considered. Compared to traditional porous medium model, present model shows a better agreement with in Realistic modeling prediction of the temperature distribution and the radial heat transfer between the inter-wrapper flow and the assembly flow.

• The Journal of the Korea Contents Association
• /
• v.5 no.4
• /
• pp.254-264
• /
• 2005

In this paper, an advanced E-Model was proposed in order to overcome disadvantages of conventional method. A new model makes the accurate VoIP call quality assessment possible by applying the burst packet loss and recency effect. In order to assess the performance of this advanced E-Model, we gained the estimated MOS value from NR(Network R) value and UR(User R) value resulted from the burst packet loss values by Gilbert Model. Through simulations and comparisons with conventional models such as MOS, PESQ, and I-Model, we reach a conclusion that advanced E-Model is more accurate and reliable method than conventional models.

• 한국IT서비스학회:학술대회논문집
• /
• 2006.11a
• /
• pp.593-599
• /
• 2006

Including technical device and general information system, the information-technical(IT) system is defined as the technical system for acquiring, processing, storing and transferring information to a person. This paper presents Knowledge-based Heuristic Evolution Model for creating the advanced information-technical system. This Evolution Model is derived from the historical review on definition of evolution, the research on the architecture of the general IT system, history of IT system, technology innovation theory and multi-case study research. The evolution model is applicable to the conceptual creation of the advanced product in R&D organization requiring development methodologies like rapid-prototyping to develop next generation product. For the detailed theoretical construction and practical application of Evolution Model, the case study research based on action research is performed. the object of the case study is mobile device, especially mobile hand-held phone. Thus, we obtain the Evolution Model for creating the advanced information-technical system.

• Journal of the Korean Society of Systems Engineering
• /
• v.14 no.2
• /
• pp.8-15
• /
• 2018

In traditional Document Based Configuration Management(DBCM) environment, changes in a system's configurations are hard to be reflected to existing engineering documents. This nature of DBCM triggers unconformities of system configurations which could become great risks. Model-based Configuration Management(MBCM) has been introduced to solve the problem of DBCM by managing system's configurations through an unified model. Therefore, it is important to model engineering documents in a general modeling language, down to low-level information items to develop traceability and flexibility of a system's engineering information. So, in the research, to explore the possibility of Model-based Approach(MBA) in the field of configuration management, a development of a systems requirement document model using SysML based Views & Viewpoints concept has been studied.

• Journal of the Society of Naval Architects of Korea
• /
• v.52 no.3
• /
• pp.180-186
• /
• 2015

This study proposed a new method of preparing granular ethylene glycol/aliphatic detergent (EG/AD) model ice that has both strength and uniform thickness. Various sheets of granular model ice prepared in ice tanks are surveyed and their preparation procedures are analyzed. We not only made a new granular model ice using the EG/AD solution but also measured its thickness, strength, and density. In addition, we found that the strength of the model ice could be controlled by varying the time and air temperature in the consolidation phase. Based on the results of this study, we verified that granular EG/AD model ice can be prepared more uniformly and effectively than columnar EG/AD model ice. This study is intended to contribute to reducing the time required for the ice model test and the operation of the ice model basin.

• Proceedings of the KIEE Conference
• /
• 1990.11a
• /
• pp.88-92
• /
• 1990

An accurate analytical threshold model is presented for fully depleted SOI which has a Metal-Insulator-Semiconductor-Insulator-Metal structure. The threshold voltage is defined as the gate voltage at which the second derivative of the inversion charge with respect to the gate voltage is maximum. Therefore the model is self-consistent with the measurement scheme. Numerical simulations show good agreement with the model with less than 3% error.