• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.6
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• pp.78-87
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• 1994

In this paper, a binary phase extraction joiont transform correlator (BPEJTC)system is proposed as a new phase-type optical correlator in which the correlation errors and DC component are dramtically reduced and optical efficiency and correlation performance are also improved by reconstructing the joint transform power spectrum (JTPS) of the conventional joint transform correlator (JTC)system form which the autocorrelation and crosscorrelation siganls generated in each self-plane are removed, and the binary phase function is extracted from the phase value of the reconstructed JTPS. Through some computer simulation and optical experimental results, the possibility of the implementation of the real-time multi-target tracking and recognition system is also suggested.

• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.2
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• pp.70-78
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• 2004

An experimental study on the pressure drop during flow boiling for pure refrigerants Rl34a and R123, and their mixture was carried out in a uniformly heated horizontal tube. Tests were run at a pressure of 0.6㎫ and in the ranges of heat flux 5-50㎾/$m^2$, vapor quality 0-100 percent and mass velocity of 150-600 kg/$m^2$s. Generally, the two-phase frictional multiplier is used to predict the frictional pressure drop during the two-phase flow boiling. The obtained results have been compared to the existing various correlations for the two-phase multiplier. Also, the frictional pressure drop was compared to a few available correlations; The Lockhart-Martinelli correlation considerally overpredicted the frictional pressure drop data for mixture as well as pure components in the entire mass velocity ranges employed in the present study, while the Chisholm correlation underpredicted the present data. The Friedel correlation was found to satisfactorily correlate the frictional pressure drop data except for a low quality region.

• Journal of Environmental Health Sciences
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• v.29 no.4
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• pp.10-16
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• 2003

Atmospheric samples were conducted from September 2001 to July 2002 with GPS-l PUF sampler in rural site to concentration distributions of gas/particle PCBs and to calculate dry deposition flux of PCBs. $\Sigma$PCBs concentrations of gas/particle PCBs were 59.29$\pm$48.83, 6.56$\pm$6.59 pg/㎥, respectively. Gas contribution (%) of total PCBs (gas + particle) was 90% which existed gas phase in the atmosphere. The particle contribution (%) of PCB congeners increased relatively more of the less volatile congeners with the highest chlorine number. The correlation coefficients (r) between total PCBs and temperature ($^{\circ}C$) showed negative correlation in - 0.62 (p<0.0l) for particle phase, positive correlation in 0.63 (p<0.01) for gas phase. In other word, particle phase PCBs is enriched in colder weather which could be due to greater in corporation of condensed gas phase at low temperature. The calculated dry deposition of total PCBs (gas + particle) was 0.008, 0.008 $\mu\textrm{g}$ $m^{-2}$ da $y^{-l}$ which showed maximum dry deposition flux in December, minimum data in July Bs in the atmosphere. The calculated dry deposition fluxes of total PCBs were influenced by particle phase PCBs even though PCBs in the atmosphere were present primarily in the gas phase.e.

• Journal of the Optical Society of Korea
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• v.5 no.3
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• pp.99-109
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• 2001

This paper presents a phase-only modulation scheme for a three-dimensional (3-D) image matching system to improve optical efficiency of the system. The 3-D image matching system is based on the two mask heterodyne scanning. A hologram of the 3-D reference object is first created and then the phase of the hologram is extracted. The phase of the hologram is represented as one mask with the other mask being a plane wave. The superposition of each beam modulated by the two masks generated a scanning beam pattern. This beam pattern scans the 3-D target object to be recognized. The output of the scanning system gives out the correlation of the phase-only hologram of the reference object and the complex hologram of the target object. Since a hologram contains 3-D information of an object as a form of fringe pattern, the correlation of holograms matches whole 3-D aspect of the objects. Computer simulations are performed with additive gaussian noise and without noise for the complex hologram modulation scheme and the phase-only hologram modulation scheme. The computer simulation results show that the phase-only hologram modulation scheme improves the optical efficiency. Thus the system with the phase-only hologram modulation scheme is more robust than the system with the complex hologram modulation scheme.

• Journal of Oral Medicine and Pain
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• v.26 no.1
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• pp.17-25
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• 2001

The purpose of this study is to evaluate the relationship of menstrual cycle and halitosis by measuring the concentrations of Voltile Sulfur Compounds, secretion rate of unstimulated saliva, secretion rate of stimulated saliva and viscosity of saliva during the menstrual cycle. The subjects were 19 female dental students of Yonsei University who had relatively good alignment of the teeth. They hadn't taken antibiotics or oral contraceptive pills during the few months prior to the experiment, and they didn't have any dental caries involving the pulp or periodontal disease. Lady-$Q^{(R)}$(Alpain Korea, Korea), which confirms the ovulation using saliva, was used to find out the menstrual cycle of subjects. Their history was taken and their basal body temperature was measured. On the basis of these data, the amount of Volatile Sulfur Compounds, secretion rate of unstimulated saliva, secretion rate of stimulated saliva, viscosity of saliva were measured during 1 day of the proliferative phase, 3 days of ovulatory phase and 1 day of the luteal phase within the menstrual cycle. The results were as follows : 1. The amount of Volatile Sulfur Compounds, secretion rate of unstimulated saliva, secretion rate of stimulated saliva, and viscosity of saliva showed no statistically significant cyclic change during proliferative phase, ovulatory phase, and luteal phase(p<0.05). 2. Between the secretion rate of unstimulated saliva and secretion rate of stimulated saliva, there was significant correlation during proliferative phase and luteal phase(p<0.05) and there was no significant correlation during ovulatory phase but relatively close result was seen. 3. The amount of Volatile Sulfur Compounds during proliferative phase and luteal phase had statistically significant correlation(p<0.05). 4. Secretion rate of stimulated saliva during proliferative phase and ovulatory phase, proliferative phase and luteal phase, ovulatory phase and luteal phase had significant correlations (p<0.01).

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.10
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• pp.1-6
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• 1997

This paper presents the theoretical derivaion relating and image correlationcoeffcient capable of assessing image quality, with phase-error variance in antenna aperture domain. We show that when the phase-error variance of a range bin selected as an adaptive beamformer is known, the quality of the reconstructed image is predictable and moreover, the resultant correlation coeffcient is obviously greater than the derive dlower boudn. To support the derivation, real data are used for image formation where the dominant scatterer algorithm (DSA) is applied for phase compensations.

• Journal of the Korean Electrochemical Society
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• v.15 no.1
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• pp.54-66
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• 2012

The phase-shift method and correlation constants, which are unique electrochemical impedance spectroscopy techniques for studying the linear relationship between the phase shift ($90^{\circ}{\geq}-{\varphi}{\geq}0^{\circ}$) vs. potential (E) behavior for the optimum intermediate frequency ($f_o$) and the fractional surface coverage ($0{\leq}{\theta}{\leq}1$) vs. E behavior, are proposed and verified to determine the Frumkin, Langmuir, and Temkin adsorption isotherms and the related electrode kinetic and thermodynamic parameters. At Ni/0.5 M $H_2SO_4$ and 0.1M LiOH aqueous solution interfaces, the Frumkin and Temkin adsorption isotherms (${\theta}$ vs. E) of H for the cathodic hydrogen ($H_2$) evolution, interaction parameters (g), equilibrium constants (K), standard Gibbs energies (${\Delta}G^0_{\theta}$) of H adsorption, and rates of change (r) of ${\Delta}G^0_{\theta}$ with ${\theta}$ have been determined using the phase-shift method and correlation constants. A lateral repulsive interaction (g>0) between the adsorbed H species appears. The value of K in the alkaline aqueous solution is much greater than that in the acidic aqueous solution.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.4
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• pp.220-232
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• 2012

In this paper, we investigate the correlation result due to the problems of delay tracking and fringe rotation module in the VCS(VLBI Correlation Subsystem). The VCS, FX-type correlator, adopts the delay tracking and fringe rotation module in order to compensate the delay change and fringe phase of wave signal from the radio source by Doppler's effect. The phase of observed data is also compensated by means of delay tracking and fringe rotation in the correlator, but we confirmed that the phase is unstable by applying long integration period of AIPS(Astronomical Image Processing System) rather than correlator. And the delay value of observed data has the errors of several tens nanoseconds than normal case at the analysis of correlation result. In addition, we found that the phase of correlation results is not connected as the unit of FFT-segment because the initial fringe phase at the fringe rotation module is not correctly determined. In this paper, in order to solve these problems, the original direction of 90 degree phase jump is reversely modified when the bit-shift occurred at the delay tracking. And the initial fringe phase at the fringe rotation module is correctly modified by using the initial phase of observed data. In addition, the parameter calculation module was abnormally operated as designed in the fringe rotation. So, the logical program by the VCS is modified so as to calculate the parameters correctly. Through the experiments of correlation processing over the above problems, the modified proposal algorithm is adequately corrected to the data analysis results, so that the experimental results make it clear for us to operate the developed VCS hardware correlator normally.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.661-666
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• 2000

Near-wake flow field of a circular cylinder is studied by means of a cinematic PIV system with high sampling rate and large internal memory block. Experiments are conducted in a closed-cycle water tunnel system and a cross-correlation algorithm in conjunction with FFT (Fast Fourier Transform) analysis and an offset correlation technique is used for vector processing. With the help of very high sampling frequency compared to the shedding frequency, it is possible to obtain phase-averaged information of the three-dimensional wake, even though the shedding is not forced but natural. Phase-locked vortical structures observed simultaneously from the spanwise and cross-stream planes are displayed in the wake-transition regime where fine-scale secondary vortices have a spanwise wavelength or around one diameter. Spatial relations and temporal evolutions of the primary Karman vortex and the secondary vortex are also discussed schematically.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.10
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• pp.51-63
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• 1995

In this paper, a new real-time optical image switching system based on the phase-typed BPEJTC is suggested. The phase filter mask which has the arbitrary position mapping function between input and output planes is constructed by using the modified JTPS of the BPEJTC. Then, the input image is convolved with this phase filter mask in the spatial frequency domain and through further Fourier transform the input image is switched to the new positions in the output correlation plane where the correlation peaks are occurred. And, based on the computer simulation results, the practical optical switched to the new positions in the output correlation plane where the correlation peaks are occurred. And, based on the computer simulation results, the practical optical switching system is opto-digitally constructed and through some experiments on image switching the possiblity of real-time implementation of the multiple optical image switching system by using the BPEJTC is suggeste.