• Wind and Structures
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• v.28 no.5
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• pp.271-284
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• 2019

This paper describes the application of a novel virtual prototyping methodology to wind turbine blade design. Numeric modelling data and experimental data about turbine blade geometry and structural/dynamical behaviour are combined to obtain an affordable digital twin model useful in reducing the undesirable uncertainties during the entire turbine lifecycle. Moreover, this model can be used to track and predict blade structural changes, due for example to structural damage, and to assess its remaining life. A new interactive and recursive process is proposed. It includes CAD geometry generation and finite element analyses, combined with experimental data gathered from the structural testing of a new generation wind turbine blade. The goal of the research is to show how the unique features of a complex wind turbine blade are considered in the virtual model updating process, fully exploiting the computational capabilities available to the designer in modern engineering. A composite Sandia National Laboratories Blade System Design Study (BSDS) turbine blade is used to exemplify the proposed process. Static, modal and fatigue experimental testing are conducted at Clarkson University Blade Test Facility. A digital model was created and updated to conform to all the information available from experimental testing. When an updated virtual digital model is available the performance of the blade during operation can be assessed with higher confidence.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.8
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• pp.1-9
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• 1992

Radio data system is a next-generation broadcasting system of digital information communication which multiplexes the digital data into the FM stereo signal in VHF/FM band and provides important and convenient service features. And radio data are composed of groups which are divided into 4 blocks with information word and check word. In this paper, radio data receiver is developed which recovers and process radio data to provide services. Then we confirm that 7dB SNR is required to be 10S0-5TBER of demodulation. Deconding process of shortened-cyclic-decoder has been simulated by computer. Also, the time-compression (by 16 times) method has been adopted for the RDS features post-processing. Via the error probability calculation, simulation and experimentation, the developed receiver system is proved to satisfy the system specification of EBU and implemented by general logic gates and analog circuits.

• Journal of KIISE:Databases
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• v.29 no.4
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• pp.285-296
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• 2002

When a client requests a set of data items at once, it is crucial to reduce the total time elapsed till the client receives all data items requested. This paper describes a data broadcasting technique that reduces access time for multiple data accesses from clients. The impact of the relative position of each data item in a broadcast schedule is dependent on the degree of data replication between data requests from clients. The relative broadcast frequencies for data items are affected by the degree of access skewness from clients. This paper proposes a technique for generation of a hierarchical data broadcast schedule, which can support multiple data accesses effectively by considering the data sharing among client requests and data access skewness together. Simulation results show that the proposed technique consistently performs better than the previous research results in various environments.

• The KIPS Transactions:PartC
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• v.10C no.6
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• pp.717-726
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• 2003

In this paper, we analyze the associated rule based deductive algorithm which creates the rules automatically for intrusion detection from the vast packet data. Based on the result, we also suggest the deductive algorithm which creates the rules of intrusion pattern fast in order to apply the intrusion detection systems. The deductive algorithm proposed is designed suitable to the concept of clustering which classifies and deletes the large data. This algorithm has direct relation with the method of pattern generation and analyzing module of the intrusion detection system. This can also extend the appication range and increase the detection speed of exiting intrusion detection system as the rule database is constructed for the pattern management of the intrusion detection system. The proposed pattern generation technique of the deductive algorithm is used to the algorithm is used to the algorithm which can be changed by the supporting rate of the data created from the intrusion detection system. Fanally, we analyze the possibility of the speed improvement of the rule generation with the algorithm simulation.

• Journal of the Korea Society for Simulation
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• v.30 no.2
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• pp.1-9
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• 2021

Many factors such as wind direction, wind strength, temperature, and obstacles affect a munition's trajectory. Since these factors eventually determines the probability of hit and the hitting point of a target, these factors should be considered to obtain reliable weapon effectiveness data. In this study, we propose the extension of the MSDL(Military Scenario Definition Language) to reflect these factors to improve the reliability of weapon effectiveness data. Based on the existing MSDL, which has been used to set the initial condition of a military simulation scenarios, the newly identified subelements are added in ScenarioID, Environment, Organizations, and Installations as a scenario schema. Also, DamageAssessment and DesignOfExperiments element are added to make weapon effectiveness data easily. The extended MSDL enables to automatically generate the simulation scenarios that reflect various factors which affect the probability of hit or kill. This extended MSDL is applied to an integrated simulation software of weapon systems, named AddSIM version 4.0 for generation of weapon effectiveness data.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1594-1600
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• 2011

Recently developed FDS5 CFD code has employed a near-wall flow treatment method which is Werner-Wengle wall law provided by NIST(National Institute of Standards and Technology). In this study, the wall law has been verified against DNS(Direct Numerical Simulation) data in the parallel plate. The $y^+$ was kept above 11 to fulfill the near-wall flow requirement in the grid generation. The total grid was $32{\times}32{\times}32$. The boundary condition for inlet and outlet was periodic condition and for both side, symmetric condition was used. The fully developed turbulent flow was generated and Re = 10,700. The simulated results were compared with DNS data. RANS results were also used for verification.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.131-136
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• 2006

Commercial uses of GPS have been growing rapidly with applications for aircraft, ship, and land vehicle navigation as well as for surveying and time keeping. The next generation GPS and Japanese QZS (Quasi Zenith Satellite) will provide three different civil signals. Galileo will also provide several types of civil signals. The availability of the third civil frequency has obvious advantages to instantaneous carrier phase accuracy and ambiguity resolution for centimeter level measurements. This paper discusses the effects of additional new civil signals for the high accuracy positioning in urban areas based on simulation using practical raw data. As for constellation, only GPS and GPS+QZS are considered. For positioning, a short distance baseline is assumed in order to disregard atmosphere effects. In this simulation, mask angle and signal conditions were fixed and ambiguity success rates were compared between different triple frequency combination scenarios. The coefficient of reflection was set randomly from 0.05 to 0.5 and the multipath delay was also set randomly from 5-100 m. Visible satellites and signal strength were determined by raw data collected in Tokyo by car. These simulation results have confirmed that the availability of high accuracy positioning will increase in all scenarios if we use GPS+QZS with triple frequencies.

• Wind and Structures
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• v.13 no.1
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• pp.57-82
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• 2010

The 486m-long roof of Shenzhen Citizens Centre is one of the world's longest spatial lattice roof structures. A comprehensive numerical study of wind effects on the long-span structure is presented in this paper. The discretizing and synthesizing of random flow generation technique (DSRFG) recently proposed by two of the authors (Huang and Li 2008) was adopted to produce a spatially correlated turbulent inflow field for the simulation study. The distributions and characteristics of wind loads on the roof were numerically evaluated by Computational Fluid Dynamics (CFD) methods, in which Large Eddy Simulation (LES) and Reynolds Averaged Navier-Stokes Equations (RANS) Model were employed. The main objective of this study is to explore a useful approach for estimations of wind effects on complex curved roof by CFD techniques. In parallel with the numerical investigation, simultaneous pressure measurements on the entire roof were made in a boundary layer wind tunnel to determine mean, fluctuating and peak pressure coefficient distributions, and spectra, spatial correlation coefficients and probability characteristics of pressure fluctuations. Numerical results were then compared with these experimentally determined data for validating the numerical methods. The comparative study demonstrated that the LES integrated with the DSRFG technique could provide satisfactory prediction of wind effects on the long-span roof with complex shape, especially on separation zones along leading eaves where the worst negative wind-induced pressures commonly occur. The recommended LES and inflow turbulence generation technique as well as associated numerical treatments are useful for structural engineers to assess wind effects on a long-span roof at its design stage.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.5
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• pp.23-32
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• 2015

The advanced receiver which can manage inter-cell interference is required to cope with the explosively increasing mobile data traffic. 3rd Generation Partnership Project (3GPP) has discussed network assisted interference cancellation and suppression (NAICS) to improve signal-to-noise-plus-interference ratio (SINR) and receiver performance by suppression or cancellation of interference signal from inter-cells. In this paper, we propose the novel hybrid receiver Full Suppression Cancellation (FSC) to reduce the interference from neighbor cell in backhaul system. The proposed receiver can suppress and cancel the interference by combining Interference Rejection Combining (IRC) with Successive Interference Cancellation (SIC). We perform the system level simulation based on 20MHz bandwidth of 3GPP LTE-Advanced system. Simulation results show that the proposed receiver can improve error rate and throughput of conventional system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.1
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• pp.81-89
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• 2005

In this paper, we have described the implementation of a practical simulation tool to design and analyze communication networks. Especially, this study is focused on the implementation and application methods of a simulator supporting VoIP The key characteristics of this particular system are its easy and intuitive usage, the real behaviors implementation of equipment and protocols, the actual generation and transmission of traffic for simulation, supporting of VoIP and so forth. Our system is distinguished from the existing tools which define only the nature of voice traffic, process those packets in the same way as general data, and analyze only the quality of packet transmission such as delay. Our tool presented in this paper generates and processes packets in different way according to the types of traffic distinguishing call signal from voice information traffic. Also, we equipped this system with the various devices such as VoIP gateway and gatekeeper, which enabled this system to analyze the performance of devices and the quality of voice traffic transmission between PSTN and Internet. By presenting the implementation methods and application of this system, we managed to propose the utilization scheme of a simulation tool.