• Progress in Superconductivity
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• v.9 no.1
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• pp.29-34
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• 2007

The baseline selection is the first and important step to analyze magnetocardiography (MCG) parameters. There are no difficulties to select the baseline between P- and Q-wave peak (P-Q interval) of MCG wave recorded from healthy subjects because the P-Q intervals of the healthy subjects do not much vary. However, patients with ischemic heart disease often show an unstable P-Q interval which does not seem to be appropriate for the baseline. In this case, T-P interval is alternatively recommended for the baseline. However, there has been no study on the difference made by the baseline selection. In this study, we studied the effect of the different baseline selection. MCG data were analyzed from twenty healthy subjects and twenty one patients whose baselines were alternatively selected in the T-P interval for their inappropriate P-Q interval. Paired T-test was used to compare two set of data. Fifteen parameters derived from the R-wave peak, the T-wave peak, and the period, $T_{max/3}{\sim}T_{max}$ were compared for the different baseline selection. As a result, most parameters did not show significant differences (p>0.05) except few parameters. Therefore, there will be no significant differences if anyone of two intervals were selected for the MCG baseline. However, for the consistent analysis, P-Q interval is strongly recommended for the baseline correction.

• Journal of Sensor Science and Technology
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• v.22 no.5
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• pp.338-345
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• 2013

Premature ventricular contractions are the most common of all arrhythmias and may cause more serious situation like ventricular fibrillation and ventricular tachycardia in some patients. Therefore, the detection of this arrhythmia becomes crucial in the early diagnosis and the prevention of possible life threatening cardiac diseases. Most methods for detecting arrhythmia require pp interval, or the diversity of P wave morphology, but they are difficult to detect the p wave signal because of various noise types. Thus, it is necessary to use noise-free R wave. So, the new approach for the detection of PVC is presented based on the rhythm analysis and the beat matching in this paper. For this purpose, we removed baseline wandering of low frequency band and made summed signals that are composed of two high frequency bands including the frequency component of QRS complex using the wavelet filter. And then we designed R wave detection algorithm using the adaptive threshold and window through RR interval. Also, we developed algorithm to classify PVC using RR interval. The performance of R wave and PVC detection is evaluated by using MIT-BIH arrhythmia database. The achieved scores indicate average detection rate of 99.76%, sensitivity of 99.30% and specificity of 98.66%; accuracy respectively for R wave and PVC detection.

• Fashion & Textile Research Journal
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• v.24 no.6
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• pp.775-781
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• 2022

As part of research to develop a permanent wave-reducing agent for hair, in the current study, 0.1%-1.0% of Polyquaternium-10 was added to a permanent reagent containing Nicotinoyl Dipeptide-23 to prepare the agent, which was tested on damaged hair. The pH change was relatively stable even after a date, but due to the hair's natural composition, 0.1%-0.6% of the Polyquaternium-10 concentration according to pH was suitable. The temperature safety experiment demonstrated it to be stable at a high temperature and at room temperature, but when a Polyquaternium-10 concentration of 0.9% or higher was added at 0℃, coagulation occurred. In terms of the force efficiency of permanent wave formation, wave efficiency lowered as the concentration increased: the longer the wave lasts, the lower the Polyquaternium-10 concentration. The permanent moisture content was found to be higher as the concentration of Polyquaternium-10 increased. Therefore, when Polyquaternium-10 is applied to the permanent wave-reducing agent, considering stability, permanent formation, durability, and moisture rate, the most suitable concentration was found to be that of Polyquaternium-10 in the cysteine-reducing agent. A novel finding from this study is that as the concentration of Polyquaternium-10 increases, the consistency of the permanent wave-reducing agent changes, shifting from a liquid to a viscous liquid formulation.

• Korean Journal of Acupuncture
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• v.26 no.2
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• pp.15-25
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• 2009

Objective: This paper aimed to understand influences on EEG conducting acupuncture stimulation, by comparing the changes in the acupoints on the body before and after normal people are treated with acupuncture at PC9 and TE3, which are referred to as Wood points(木穴), and PC5 and TE1, which are referred to as the Metal points(金穴) among the five shu points of Yin pericardium Meridian and Yang Triple Energizer Meridian. Methods: The study was performed on 30 healthy female volunteers in their 20's. EEG was measured for 5 minutes before acupuncture stimulation was conducted on PC9, TE3, PC5 and TE1. During 20 minutes of acupuncture treatment, the same items were continuously measured to find out whether there were any changes in them, and they were measured for 5 minutes after removing the acupuncture needles in order to implement a comparative analysis. Results: Comparision of EEG data before and after the treatment at PC9 shows no significant differences in all wave. Compared with the pre-acupuncture period at TE3, $\delta-\theta$ wave decreased significantly (P<0.05) during the acupuncture stimulation periods. Compared with the pre-acupuncture period at PC5, $\delta-\theta$ wave and high $\alpha$ wave increased significantly (P<0.05) during the acupuncture stimulation periods. And Mid $\beta$ wave and high $\beta$ wave decreased significantly (P<0.05) during the acupuncture periods and the post acupuncture periods. Compared with the Pre-acupuncture period at TE1, $\delta-\theta$ wave, $\theta$ wave and high $\alpha$ wave increased significantly (P<0.05) during the acupuncture stimulation periods. And Low $\beta$ wave decreased significantly (P<0.05) during the acupuncture periods. Conclusion: When acupuncture stimulation was performed on PC9 and TE3, referred to as the "Wood points", brain waves were stabled, while when acupuncture was performed on PC5 and TE1, called the "Metal points", a brain was waked. From the findings of this study, we hypothesize that the wood properties, from which growing starts in all things, are related with fast waves of EEG, and the metal properties, which stabilize and converge in all things, are related with slow waves of EEG.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.461-464
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• 2009

The characteristics of slow wave structure employed for backward wave oscillators expected to be a high power microwave source are studied analyytically. The slow wave structure is a sinusoidally corrugated wall waveguide. The waveguide is designed and fabricated by cast aluminun. The dispersion relation and transmitted characteristics for microwaves are measured in the air. There exist literatures on high efficiency of enhanced radiation from backward wave oscillators involving plasma studied experimentally.

• International Journal of Reliability and Applications
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• v.5 no.1
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• pp.1-13
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• 2004

It is recently well recognized that the technique for the one-sided stress wave velocity measurement in structural materials provides measurement in structural materials provides valuable information on the state of the material such as quality, uniformity, location of cracked or damaged area. This technique is especially effective to measure velocities of longitudinal and Rayleigh waves when access to only one surface of structure is possible. However, one of problems for one-sided stress wave velocity measurement is to get consistent and reliable source for the generation of elastic wave. In this study, the laser based surface elastic wave was used to provide consistent and reliable source for the generation of elastic wave into the materials. The velocities of creeping wave and Rayleigh wave in materials were measured by the one-sided technique using laser based surface elastic wave. These wave velocities were compared with bulk wave velocities such as longitudinal wave and shear wave velocities to certify accuracy of measurement. In addition, the mechanical properties such as poisson's ratio and specific modulus(E/p) were calculated with the velocities of surface elastic waves.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.5
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• pp.733-738
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• 2013

Orthogonal Frequency Division Multiplexing (OFDM) based IEEE 802.11 a/g systems which are widely used in wireless LAN carry out channel estimation in one time per packet since the systems use only preamble. Whereas, midamble based channel estimation supports continuous channel estimation by tracking the channel state information periodically. Using IEEE 802.11p Wireless Access in Vehicular Environments (WAVE) system, we analyze the performance of the proposed system via practical measurements. Based on these results, practical issues on midamble based channel estimation are investigated.

• Geophysics and Geophysical Exploration
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• v.9 no.1
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• pp.10-18
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• 2006

We measured the changes in P-wave velocity that occur when injecting $CO_2$ in gaseous, liquid, and supercritical phases into water-saturated anisotropic sandstones. P-wave velocities were measured in two cylindrical samples of Tako Sandstone, drilled along directions normal and parallel to the bedding plane, using a piezo-electric transducer array system. The velocity changes caused by $CO_2$ injection are typically -6% on average, with maximum values about -16% for the case of supercritical $CO_2$ injection. P-wave velocity tomograms obtained by the differential arrival-time method clearly show that $CO_2$ migration behaviour is more complex when $CO_2$ flows normal to the bedding plane than when it flows parallel to bedding. We also found that the differences in P-wave velocity images were associated both with the $CO_2$ phases and with heterogeneity of pore distribution in the rocks. Seismic images showed that the highest velocity reduction occurred for supercritical $CO_2$ injection, compared with gaseous or liquid $CO_$ injection. This result may justify the use of the seismic method for $CO_2$ monitoring in geological sequestration.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.705-712
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• 2001

It is of great importance to represent the directional ocean waves in a laboratory basin for hydraulic model tests. The directional ocean waves can be expressed as a linear superposition of a large number of component waves with different frequencies and propagating directions. The aim of the study is to check the wave generating characteristics by serpent-type wave generating system in PKNU (Pukyong National University) which is composed of 10 piston-type wave generators. In the experiment, spatial variation of irregular wave heights and propagating angles are measured in the multi-directional wave maker basin. Target wave directional spectrum is reproduced in the area of multi-directional wave maker basin. The directional spreading of the generated waves varied spacially in the basin. They differed from target spectrum as the measurement point becomes far from the center line normal to the generator face, The effective generation area where that target can be reproduced is limited to the triangular area attached the generator face. According to the results, it is emphasized that the effective experiment area in the basin considered wave generator characteristics should be determined in consideration of experimental conditions including structural shapes, water depth, wave directionality etc.

• Geophysics and Geophysical Exploration
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• v.10 no.1
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• pp.1-18
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• 2007

Non-linear elastic wavefield inversion is a powerful method for estimating elastic parameters for physical constraints that determine subsurface rock and properties. Here, I introduce six elastic-wave velocity models by reconstructing elastic-wave velocity variations from real data and a 2D elastic-wave velocity model. Reflection seismic data information is often decoupled into short and long wavelength components. The local search method has difficulty in estimating the longer wavelength velocity if the starting model is far from the true model, and source frequencies are then changed from lower to higher bands (as in the 'frequency-cascade scheme') to estimate model elastic parameters. Elastic parameters are inverted at each inversion step ('simultaneous mode') with a starting model of linear P- and S-wave velocity trends with depth. Elastic parameters are also derived by inversion in three other modes - using a P- and S-wave velocity basis $('V_P\;V_S\;mode')$; P-impedance and Poisson's ratio basis $('I_P\;Poisson\;mode')$; and P- and S-impedance $('I_P\;I_S\;mode')$. Density values are updated at each elastic inversion step under three assumptions in each mode. By evaluating the accuracy of the inversion for each parameter set for elastic models, it can be concluded that there is no specific difference between the inversion results for the $V_P\;V_S$ mode and the $I_P$ Poisson mode. The same conclusion is expected for the $I_P\;I_S$ mode, too. This gives us a sound basis for full wavelength elastic wavefield inversion.