• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.17-20
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• 2001

This paper studies the channel estimation schemes of Time Division Duplex (TDD) Code Division Multiple Access (CDMA) system with a parallel interference cancellation (PIC) scheme in the multi-Path fading channel. Also, the effective interpolation scheme which maintains the merits of WCDMA TDD mode is proposed. By Monte Carlo simulations, it is shown that the proposed interpolation method can be used in order to obtain the proper performance of a multi-stage PIC and in order to reduce the required Eb/No in the second stage at a BER= 10$^{-2}$

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.678-683
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• 2008

Moment-based reliability analysis is the method to calculate reliability using Pearson System with first-four raw moments obtained from simulation model. But it is too expensive to calculate first four moments from complicate simulation model. To overcome this drawback the MD(multiplicative decomposition) method which approximates simulation model to kriging metamodel and calculates first four raw moments explicitly with multiplicative decomposition techniques. In general, kriging metamodel is an interpolation model that is decomposed of global model and local model. The global model, in general, can be used as the constant global model, the 1st order global model, or the 2nd order global model. In this paper, the influences of global models on the accuracy and robustness of raw moments are examined and compared. Finally, we suggest the best global model which can provide exact and robust raw moments using MD method.

• Journal of Information Technology Services
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• v.3 no.2
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• pp.105-118
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• 2004

Since Component-Based Development, or CBD, struck Korea SI industry a heavy blow several years ago, many major SI companies in Korea have implemented the CBD practices in real world, leveraging supports from the government and academic world. The result, however, falls short of their expectations. The major reason is that they have mainly focused on CBD processes and technical issues around it, although it is necessary as well to deal with other non-technical issues in order to make business values from CBD. This paper begins with reminding us what CBD tries to achieve indeed in terms of software development processes, then recognizes what we have achieved so far introducing a recent CBD project case, BOK-WIRE system. Thereafter, it reveals the chances that SI companies must take in order to make their CBD efforts succeed, pointing out what are the roadblocks really.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.2
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• pp.189-194
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• 2005

The food wastes recycling system should be constructed before 2005 in the city area. In order to manufacture the good compost, salt remaining rate should be minimized. We studied the effective method of minimizing salt ratio by diluting with low water ratio. We got the salt remaining ratio less than 0.3% by effective fragmentation method, and we applied the IR heating in order to make good compost.

• Electrical & Electronic Materials
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• v.7 no.1
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• pp.42-48
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• 1994

The preventive diagnosis technique for power system is being highlighted as a research area for deterioration of insulation in machinery because of high-voltage power system. We make efforts to develop not only diagnosis of aging state but also detection of defects in the initial stage from preventive diagnosis technique. Especially, partial discharge is actively studied as a non-destructive diagnosis technique and very useful because partial discharge measurement reduces damage than conventional diagnosis technique. The loaded stress during this test is smaller than that of other diagnosis techniques. But the continuous research for various complicated analysis method is required because partial discharge has very small signals and its signals have complex forms. In this paper, the measurement of partial discharge was investigated and studied on many specimens with void. We made samples having artificial voids and measured partial discharge. In order to use as a practical diagnosis technique, we studied ways of measurement, measured illustrations and types of partial discharge which could be used in order to diagnose defects of power machinery.

• Journal of Welding and Joining
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• v.19 no.2
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• pp.200-207
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• 2001

Three-diemnsional bead profile was measured using the biprism stereo vision sensor in GMAW, which consists of an optical filter, biprism and CCD camera. Since single CCD camera is used, this system has various advantages over the conventional stereo vision system using two cameras such as finding the corresponding points along the horizontal scanline. In this wort, the biprism stereo vision sensor was designed for the GMAW, and the linear calibration method was proposed to determine the prism and camera parameters. Image processing techniques were employed to find the corresponding point along the pool boundary. The ism-intensity contour corresponding to the pool boundary was found in the pixel order and the filter-based matching algorithm was used to refine the corresponding points in the subpixel order. Predicted bead dimensions were in broad agreements with the measured results under the conditions of spray mode and humping bead.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.2
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• pp.104-111
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• 2003

Micro force measurement is required more frequently for a precision manufacturing and investment in fields of precision industries such as semiconductor, chemistry and biology, and so forth. Null balance method has been introduced as an alternative of a loadcell. Loadcells have advantages in aspects of low cost and easy manufacturing, but have also the limitation in resolution and sensitivity to environment variations. In this paper, null balance method is explained and the dominant parameters related to system performances are mentioned. Null position sensor, electromagnetic system and controller are investigated. Also, the characteristic experiment is carried out in order to estimate the resolution and the measurement range. In order to overcome the limitation by the drift of position sensor and the performance of controller, double electromagnetic force compensation method is proposed and experimented. After controlling and filtering, the resolution under $\pm$ 1mg and measurement range over 300g could be obtained.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4A
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• pp.345-355
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• 2011

This paper introduces the coded cooperation protocol in wireless relay network. We propose a two relay based coded cooperation protocol with RCPC codes for wireless networks. The proposed two-relay based system can achieve a diversity of order 4 under slow fading environment. Under fast fading, the diversity order is 2 times of the free distance of the convolutional code. We develop upper bounds on BER and FER for the system under both slow and fast fading with Rayleigh distribution. The effect of various channel conditions on the cooperation is also examined in this work.

• Computational Structural Engineering
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• v.7 no.2
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• pp.131-138
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• 1994

Derivatives of eigenvalues and eigenvectors for statistical properties is presented. Dynamic response of random system including uncertainties for the design variable is calculated with the first order perturbation method to original governing equation. In optimal design methods, there is fundamental requirement for design gradients. A method for calculating the sensitivity coefficients is developed using the governing equation and first order perturbed equation.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.12
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• pp.20-26
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• 1994

Lossless system has been employed to design the perfect reconstruction filter banks and has particularly a close relation with the desing of orthogonal wavelet filter (OWF). With such a relation, we generalize 2-band OWF to the M-band OWF which has an improved performances. The improvement is achieved using the two techniques. One is that the wavelet low pass filter has (N-1)th order regularity with extra zeros while the existing filter has N-th order regularity. The other is that unitary matrix is designed by adding the zeros to the proper positions. As a result, M-band OWF designed by propose method has better performance than M-band OWF designed by exsiting method.