• Korean Membrane Journal
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• v.5 no.1
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• pp.61-67
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• 2003

Various characteristics of ion transport properties of a charged mosaic membrane with a parallel array of positive and negative functional charges were investigated, From the analysis of the volume flux, it was found that the salt flux based on nonequilibrium thermodynamics, preferential salt transport across the charged mosaic membrane. Transport properties of the magnesium sulfate(MgSO$_4$) and sucrose across the charged mosaic membrane were estimated. As a result, metal salts transport depended largely on the charged states and molecular weight otherwise nonelectrolyte solution was rejected under all experimental conditions. On the other hand, the reflection coefficient s indicated the negative value that suggested preferential material transport and was independent of charged mosaic thickness.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1435-1438
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• 1994

The effects of Ge composition variation in $a-Si_{1-x}Ge_x:H$ alloy p-i-n solar cells on the physical properties and current density-voltage characteristics are analyzed by a new simulation modelling based on the update published experimental datas. The simulation modelling includes newly formulated density of gap density spectrum corresponding to Ge composition variation and utilizes the newly derived generation rate formulars which include the reflection coefficients and can apply to multijunction structures as well as single junction structure. The effects in $a-Si_{1-x}Ge_x:H$ single junction are analyzed through the efficiency, fill factor, open circuit voltage, short circuit current density, free carriers, trap carriers, electric field, generation rate and recombination rate. Based on the results analyzed in single junction structure, the applications to multiple junction structures are discussed and the optimal conditions reaching to a high performance are investigated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2A
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• pp.198-203
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• 2008

In this paper, we consider the diffuse type of indoor wireless optical communication (WOC) system. To find the channel characteristics of indoor wireless infrared communication system, we investigate the simulation process to get the impulse response of diffuse type and analyze the scenario of the indoor structure which we have built. The simulation results of the impulse response include power ratio and time delay due to bounce times. We get and discuss the receiving power distribution according to six configurations which have different transmitter and receiver positions and reflection coefficients of the indoor structure assumed. The results of this paper are useful to design the indoor wireless optical communication systems.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.6
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• pp.76-82
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• 1985

The convergence properties of Burg algorithm, which is commonly used to calculate the reflection coefficients in the adaptive lattice filters, are studied in this paper. Applying the $\mu$ algorithm to Burg algorithm, a new adaptive lattice $\mu$ algorithm is derived and it shows that the convergence speed of this algorithm is higher than that of Burg algorithm. As a result of theoretical analysis and computer simulation, it is proved that the con-vergence speed of the proposed algorithm is remarkably higher than that of Burg algorithm when the convergence speed of Burg alsorithm is low.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.11
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• pp.20-24
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• 1990

A fast convergent solution to the scattering problem of a transverse electric (TE) plan wave by a periodic strip grating with a dielectric slab is considered. The present method follows from an expansion of the equivalent surface magnetic current placed over the shorted slot according to the equivalence principle in a series of Chebyshev polynomials satisfying the appropriate edge condition. To examine the accuracy and convergence of the present method, the numerical results are calculated for the reflection and transmission coefficients and compared with other results available in the literature.

• Journal of Industrial Technology
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• v.30 no.A
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• pp.69-73
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• 2010

In this paper, we designed the RF-DC converter used in wireless power transmission system and studied how to design the RF-DC converter of high conversion efficiency. The RF-DC converter operate at 2.45GHz and the diode is connected with series. The RF-DC converter uses shorted stub for DC loop and matching. We can divide the RF-DC converter circuit into four blocks. The reflection coefficients between the blocks were optimized for the maximum conversion efficiency at 0 dBm input power and $1300{\Omega}$ load impedance. The final design of the RF-DC converter has a 52 percent conversion efficiency.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.6
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• pp.553-563
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• 2008

If an arbitrary topography is approximated to a number of vertical steps, both variational approximation and eigenfunction expansion method can be used to compute linear wave transformation over the bottom. In this study a scatterer method associated with variational approximation is proposed to calculate reflection and transmission coefficients. Present method may be shown to be more simple and direct than the successive-application-matrix method by O'Hare and Davies. And Several numerical examples are given which are in good agreement with existing results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.2
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• pp.145-149
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• 2006

UHF band omnidirectional antennas for RFID tag were designed. Crossed loaded dipole and bended dipole were applied to be designed for both miniaturization and omnidirectional radiation pattern. By suppling 90 degrees phase difference between crossed dipoles, omnidirectional E-plane patterns can be obtained. -10 dB reflection coefficients of 3 types dipole antenna which have designed under conjugate matched with input impedance of chip were shown as 670-1,050 MHz, 700-1,250 MHz and 600-1,020 MHz, respectively, and also shown that all antenna have omnidirectional radiation pattern both E and H plane.

• Proceedings of the KSPS conference
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• 2005.11a
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• pp.51-54
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• 2005

This paper analyzes the vocal tract area estimation algorithm used as a part of a speech analysis program to help deaf children correct their pronunciations by comparing their vocal tract shape with normal children's. Assuming that a vocal tract is a concatenation of cylinder tubes with a different cross section, we compute the relative vocal tract area of each tube using the reflection coefficients obtained from linear predictive coding. Then, obtain the absolute vocal tract area by computing the height of lip opening with a formula modified for children's speech. Using the speech data for five Korean vowels (/a/, /e/, /i/, /o/, and /u/), we investigate the effects of the sampling frequency, frame size, and model order. We compare vocal tract shapes obtained from deaf and normal children's speech.

• Journal of Mechanical Science and Technology
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• v.20 no.2
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• pp.185-190
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• 2006

An ultrasonic self-calibrating technique for the characterization of a ceramic which was fabricated by change pressing time during the HIP process has been applied by using the ratio of the reflection and transmission coefficients of normal incidence longitudinal waves. The ratio is self-compensated, in that it is independent of the characteristics for transmission and reception of ultrasound by the transducer and the condition of the couplant. The insensitive direction in parameter space is defined as the direction in which the variation of the ratio to changes of two parameters vanishes. For inverse problem the distribution of minima in an error surface is investigated.