• Journal of Korean Institute of Industrial Engineers
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• v.40 no.1
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• pp.135-139
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• 2014

In a connection-oriented packet switching network, the data communication starts after a virtual circuit is established between source and destination. The virtual circuit establishment time includes the queue waiting times in the direction from source to destination and the other way around. We use this two-way queueing delay to evaluate scheduling policies of a packet switching processor through simulation studies. In this letter, we also suggest user testing functions for the packet switching processor to manage virtual circuits. By detecting error causes, the user testing helps the packet switching processor provide reliable connection-oriented services.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.4
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• pp.566-574
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• 2013

In this paper, direct power control system for three-phase PFC AC/DC converter without the source voltage sensors is proposed. The sinusoidal input current and unity effective power factor are realised based on the estimated flux in the observer. Both active and reactive power calculated using estimated flux. The estimation of flux is performed based on the reduced-order virtual flux observer using the actual currents and the command control voltage. Moreover, source voltage sensors are replaced by a estimated flux. DC output voltage has been compensated by DC output ripple voltage estimation algorithm. The active and reactive powers estimation are performed based on the estimated flux and Phase angle. The proposed algorithm is verified through simulation and experiment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.76-80
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• 2000

This paper describes a coordinate measuring technique based on optical triangulation using the two images. To overcome the defect of structured light system which measures coordinate point by point, light source is replaced by CCD camera. Pixels in CCD camera were considered as virtual light source. The overall geometry including two camera images is modeled. Using this geometry, the formula for calculating 3D coordinate of specified point is derived. In a word, the ray from a virtual light source was reflected on measuring point and the corresponding image point was made on the other image. Through the simulation result, validation of formula is verified. This method enables to acquire multiple points detection by photographing.

• Journal of Environmental Impact Assessment
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• v.14 no.5
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• pp.291-303
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• 2005

Impact pathway analysis(IPA) is a bottom-up approach to estimates health and environmental risks from emissions of classical pollutants (eg. $PM_{10}$, $SO_2$, $NO_x$ and CO). The model starts from the emission rates of facility, calculates the yearly mean concentrations of pollutants at the ground level using atmospheric dispersion models. After this, proper epidemiological exposure-response functions are applied to determine the impact on the receptors. Finally the methodology can monetise the calculated physical impact on the basis of selected economic evaluation. The aim of this study is to evaluate an external cost of virtual point source in Suwon area using IPA. The results shows minor modification of local input data can make it possible to apply the model to Suwon area.

• Journal of Korean Society on Water Environment
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• v.27 no.1
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• pp.30-35
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• 2011

2D pollutant transport model was applied to the simulation of contaminant transport in the channel. At first, two kinds of virtual channels having different slopes were designed. The distribution of contaminant, which flows from one of the three drainages to the main channel, was simulated by each 2D model. Concentrations of 745 nodes were converted to input data of neural network model (Multi-perceptron) for training and verification using matrix. The first three cases (Case A-1, A-2, A-3) were used for training Multi-perceptron, the other three cases (Case B-1, B-2, B-3) were used for verification. As a result, Multi-perceptron reasonably divided the cases into the three characteristics which have different contaminant distributions due to the different input point of water pollution source. It can be a useful methodology for the water quality monitoring and backtracking.

• Smart Media Journal
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• v.3 no.4
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• pp.9-15
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• 2014

A virtual platform models a processor core and the peripheral devices constituting the SoC in software. Major companies utilize a variety of platforms for product development with optimal SW+SoC integrated system architecture design and IP reuse based Top-Down design flow using a virtual platform. In this paper, we propose a virtual platform based on OpenRISC, an open source RISC based core. The proposed virtual platform supports high speed emulation of approximately 20 MIPS using DBT (Dynamic Binary Translation).

• Journal of the Korea Society of Computer and Information
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• v.22 no.7
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• pp.83-91
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• 2017

In this paper, we propose a thorough solution for adjusting virtual sound field with different kinds of devices and software in preliminary procedure and late stage of music processing. The basic process of music production includes composing, arranging and recording at pre-production stage as well as sound mixing and mastering at post-production stage. At the initial stage of music creation, it should be checked whether the design of virtual sound field, the choice of the tone and the instrument used in the arrangement match the virtual sound field required for the final work. In later recording, mixing and mastering, elaborate adjustments should be done to the virtual sound field. This study also analyzed how to apply the parameter of the effectors to the design and adjustment of the virtual sound field, making it the source of our creation.

• Journal of the Korea Society of Computer and Information
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• v.22 no.1
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• pp.77-87
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• 2017

In this paper, we propose an analysis of the sound source of virtual orchestral music in detail by using the production technology of sampling and playback, and technical experiments and verification for the most advanced Hollywood Library series of timbre and the timbre production and control technology of Vienna instrument Pro and other softwares, to find their solutions and come up with the best timbre production method for orchestral music from the perspective of the specific design ideas of the productions of virtual orchestral instruments. The so-called virtual orchestral instruments are non-real orchestral instruments, which are based on the imitation of timbre of real orchestral instruments, processed and synthesized through the scientific and technological means, and produced by the use of electronic equipments or computers. The study of virtual timbre production technology is very important, and it is like the study of composers' creative techniques. Not only scientific and advanced timbre production methods can be obtained from the study, but also new ways of future timbre production are expected to be explored.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.203-207
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• 2008

Prestack depth migration is used to image for complex geological structure such as faults, folds, and subsalt. In this case, it is widely used the surface reflection data as a input data. However, the surface reflection data have intrinsic problems to image the subsalt and the salt flank due to the complex wavefields and multiples which come from overburden. For overcoming the structural defect of the surface reflection data in the imaging, I used the virtual sources in terms of seismic interferometry to image the subsurface and suppress the multiples using the velocity model of the lower part of the virtual sources. The results of the prestack depth migration using virtual source gathers and velocity model below receivers are similar geological interfaces to the results from shot gathers of the conventional ocean bottom seismic survey. And especially artificial interfaces by multiples were suppressed without applying any other data processing to eliminate multiples. This study results by numerical modeling can make a valuable imaging tool when it is applied to satisfied field data for specific condition.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.6
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• pp.564-573
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• 2012

The objective of this study is to determine the effect for the sound quality according to the noise source and to build the sound quality index of the laundry noise. In order to compare laundry noise among the influence of noise sources, we made virtual laundry noises by synthesizing an actual laundry noise and each noise source such as a dropping noise, water noise, motor noise and circulation pump noise. We conducted a listening test by customers using virtual laundry noises. As a result of listening test, we found that the dropping noise has a decisive effect on the sound quality of the laundry noise. We conducted the multi regression analysis of sound quality for the laundry noise using the statistical data processing. It is verified to the reliability of the multi regression index by comparison with listening results and index results of other actual laundry noises. This study is expected to provide a guide line for improvement of the laundry noise.