• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1874-1881
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• 2010

A recursive linear stochastic error compensation algorithm is newly proposed for target localization in sensor network which provides range difference of arrival(RDOA) measurements. Target localization with RDOA is a well-known nonlinear estimation problem. Since it can not solve with a closed-form solution, the numerical methods sensitive to initial guess are often used before. As an alternative solution, a pseudo-linear estimation scheme has been used but the auto-correlation of measurement noise still causes unacceptable estimation errors under low SNR conditions. To overcome these problems, a stochastic error compensation method is applied for the target localization problem under the assumption that a priori stochastic information of RDOA measurement noise is available. Apart from the existing methods, the proposed linear target localization scheme can recursively compute the target position estimate which converges to true position in probability. In addition, it is remarked that the suggested algorithm has a structural reconciliation with the existing one such as linear correction least squares(LCLS) estimator. Through the computer simulations, it is demonstrated that the proposed method shows better performance than the LCLS method and guarantees fast and reliable convergence characteristic compared to the nonlinear method.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.5
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• pp.717-727
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• 2004

In this study, we simulate the aerodynamic sounds generated by a two-dimensional circular cylinder in a uniform flow are simulated by applying the finite difference lattice Boltzmann method (FDLBM). The third-order-accurate up-wind scheme (UTOPIA) is used for the spatial derivatives. and the second-order-accurate Runge-Kutta scheme is applied for the time marching. The results show that we successively capture very small acoustic pressure fluctuations with the same frequency of the Karman vortex street compared with the Pressure fluctuation around a circular cylinder The propagation velocity of the acoustic waves shows that the points of peak pressure are biased upstream due to the Doppler effect in the uniform flow For the downstream. on the other hand. it quickly Propagates. It is also apparent that the amplitude of sound Pressure is Proportional to $r^{-1/2}$, r being the distance from the center of the circular cylinder. To investigate the effect of the lattice dependence furthermore a 2D computation of the tone noise radiated by a NACA0012 with a blunt trailing edge at high incidence and low Reynolds number is also investigated.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.3 s.18
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• pp.73-82
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• 2005

The scheme for the conveyance increasement of urban river is presented in this study. For the use of the lower part of the road paralleled to urban river as a conveyance, the 2-dimensional flood flow between main channel and added conveyance section is analyzed by mathematical model SMS(2-D simulation model). The result of the HEC-RAS(1-D simulation model) is used to calibrate the parameters of SMS. New scheme is applied to the Cheonggeyecheon Restoration Project. The capacity of flood flow between main channel and added conveyance is simulated for 50, 80, 200 year frequency flood and suitable size of pathway is proposed.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.4
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• pp.295-304
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• 2014

Communication infrastructure supports wide variety of mobile services such as photo and file sharing, location tracking, social network services and instant messaging. However, instances like power-loss and natural disasters disrupt these communication infrastructures unable to render support to these mobile services. Delay-tolerant networks (DTNs) offer a solution to these problems at hand. By utilizing mobility and opportunistic contacts among mobile devices, a plausible communication network can be establish and enable support to mobile applications. This paper presents an energy-efficient, reliable message delivery routing scheme with message prioritization rules for DTN. It uses the context information of nodes (mobile devices) such as the contact history (location and time of contact), speed/velocity, moving direction to determine the best forwarders among nodes in the network. The remaining energy of the nodes is also used to determine the message types a node can deliver successfully. The simulation results show that proposed approach outperforms Epidemic and Prophet routing schemes in terms of delivery ratio, overhead ratio, delivered messages per types and remaining energy.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.4
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• pp.53-58
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• 2012

The roadside unit (RSU) collects vehicle information from vehicles in the intelligent transportation system (ITS). The vehicle density on the road within the communication range of a RSU is a time varying parameter. The higher the vehicle density, the more vehicle information can be collected. Therefore, the probability of packet collision will be raised. In this paper, an adaptive transmission scheme is proposed to improve the probability of packet reception rate by changing the data rate and transmission period according to the vehicle density. The performance of IEEE 802.11p MAC protocol that is a standard for vehicular communications is evaulated in terms of the vehicle density with the ns-2,33 simulator.

• Nuclear Engineering and Technology
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• v.34 no.3
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• pp.218-231
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• 2002

Using a three-dimensional numerical code, B3R developed for nuclide transport of an arbitrary length of decay chain in the buffer between the canister and adjacent rock in a high- level radioactive waste repository by adopting a finite difference method utilizing the control- volume scheme, some illustrative calculations have been done. A linear sorption isotherm, nuclide transport due to diffusion in the buffer and the rock matrix, and advection and dispersion along thin rigid parallel fractures existing in a saturated porous rock matrix as well as diffusion through the fracture wall into the matrix is assumed. In such kind of repository, buffer and rock matrix are known to be important physico-chemical harriers in nuclide retardation. To show effects of buffer and rock matrix on nuclide transport in HLW repository and also to demonstrate usefulness of B3R, several cases of breakthrough curves as well as three- dimensional plots of concentration isopleths associated with these two barriers are introduced for a typical case of decay chain of $^{234}$ Ulongrightarrow$^{230}$ Thlongrightarrow$^{226}$ Ra, which is the most important chain as far as the human environment is concerned.

• Journal of Information Technology Services
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• v.5 no.3
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• pp.121-135
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• 2006

With the growth and maturation of IT industry, the necessity of audit about development, maintenance and management of high-quality information system is gradually increasing. In addition, the necessity of inner auditing system, which could totally verify and evaluate the effectiveness of project according to the characteristics of organization conducting information-oriented business, also being proposed. Government offices including Korea Institute of Science and Technology(KISTI) collectively controlling nationwide science-technology related information have no guiding principle or organization within themselves even though performing information-oriented businesses are becoming more bigger and complicated. In this paper, we propose scheme for devising framework, which can audit construction and operation of knowledge information, check list and guideline. In addition, we present concrete ways for adapting these schemes to institutes which manage science-technology knowledge information. Audit framework consists of points of time in audit, audit domain and audit criterion. Points of time in audit are defined as three phases as followings: pre-audit, in-progress audit and post-audit. Audit domain includes 16 detail audit domains and especially we set 11 check items and 40 detail investigation items for database implementation business. We expect that management level of science-technology implementation business of organizations using this research result will increase and they could offer high-quality information service.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.1
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• pp.74-82
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• 2019

The revolution of industry 4.0 is enabling us to build an intelligent connection society called smart cities. The use of renewable energy in particular solar energy is extremely important for modern society due to the growing power demand in smart cities, but its difficult to monitor and manage in each buildings since need to be deploy low energy sensors and information need to be transfer via wireless sensor network (WSN). The Internet of Things (IoT) / low-power wide-area (LPWA) is an emerging WSN technology, to collect and monitor data about environmental and physical electrical / electronics devices conditions in real time. However, providing power to IoT sensor end devices and other public electrical loads such as street lights, etc is an important challenging role because the sensor are usually battery powered and have a limited life time. In this paper, we proposes an efficient solar energy-based power management scheme for smart city based on IoT technology using LoRa wide-area network (LoRaWAN). This approach facilitates to maintain and prevent errors of solar panel based energy systems. The proposed solution maximizing output the power generated from solar panels system to distribute the power to the load and the grid. In this paper, we proved the efficiency of the proposed system with Simulink based system modeling and real-time emulation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.5
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• pp.42-53
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• 2000

Efficient implementation of pre-filtering has been an important issue in video sequence coding, because it can remove camera noise and improve coding efficiency dramatically This paper introduces a novel pre-filtering scheme that is performed inside a video encoder The proposed pre-filtering is based on the approximated generalized Wiener filtering and two-dimensional discrete cosine transform (DCT) factorization. and is achieved by scaling the DCT coefficients of original image blocks for intra block coding and those of motion-compensated error blocks for inter block coding, respectively Even though the pre-filtering operation is embedded in a video encoder, its additional computational complexity is marginal compared to the encoding process, and the overall architecture of the conventional video encoder is maintained In spite of its simplicity, the proposed pre-filtering scheme provides good filtering and coding performance for noisy video sequences.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.2
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• pp.16-30
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• 1990

The microwave imaging technique which is mostly analyzed in the spectral domain has been exploited the image reconstruction of object using the 2-dimensional inverse Fourier transform so far. In this paper, a new method of microwave imaging corresponding to a coherent tomographic scheme in the space domain is presented for the conducting objects. Also, it is shown that image reconstruction for lines targets and conducting circular cylinder is per-formed by computer simulation using the filtered-backprojection which is the reconstruction algorithm widely used in X-ray CT. The proposed method analyzed in the space domain can reconstruct the image without any problems such as interpolation and image artifact which results from the reconstruction in the spectral domain for the symmetric conducting objects located in the origin. The image reconstructed by the filtered-backprojection in the space domain has given the superior quality compared with that produced by 2-dimensional IFFT using the interpolation scheme in the spectral domain. Finally, the image of line targets using the moment-method in the space domain which does not require the wide-band signal as the spectral domain has shown a possibility of super-resolution in the microwave imaging.