• Tunnel and Underground Space
• /
• v.28 no.5
• /
• pp.476-492
• /
• 2018

In this study, various laboratory experiments were conducted on tuff, basalt and diorite specimens, which were obtained in the southern part of Korean Peninsula. Experiments were performed under dry and water saturated conditions. Results showed that strength degradation and change of deformation characteristics were remarkable although the specimens had small porosity. Based on the results, regression models that are capable of predicting important mechanical rock properties, such as uniaxial compressive strength, Young's modulus, Brazilian tensile strength were proposed. P-wave velocity and Shore hardness were selected as independent variables and the results showed satisfactory prediction performance for the experimental data collected in this study.

• The Journal of Engineering Geology
• /
• v.4 no.3
• /
• pp.333-341
• /
• 1994

The low velocity body was detected during the invesfigation of the crustal structune and upper mantle in the Korean Peninsula using ray method and observational seismic data. We observed the arrival time delays of P and S waves that pass through the Bugok hot spring area and the chugaryong rift zone in the Korean Peninsula. The present geothermal exploration accounts for the high heat flow in these regions, suggesting that the area are the 'delay shadows' produced by a deep, low velocity body(Resenberg et aL, 1980). We tried to verify the hypothesis that the low-velocity body is caused by the partial melting in the lower crust can be explained by the lateral variation(inhomogeneous model) of the lower crust velocity using Ray Method(Cerveny and Psencik, 1983).

• Journal of Korea Multimedia Society
• /
• v.19 no.6
• /
• pp.1034-1042
• /
• 2016

The detection of P-waves and T-wave in the electrocardiogram signal analysis is an important issue. But the accuracy of the boundary detection algorithm is an insufficient level in the change of slow transition in the signal compared to the QRS complex. This study proposes an algorithm to detect P-wave and T-wave sequentially after determining local baseline using QRS complex. First, we detected the peak points based on local baseline and determined the onset and offset through the calculation of the area of the section. After modifying the baseline using detected waveform, we detected the other waveform in the same way and separated the P-wave and the T-wave based on the location. We used the PhysioNet QT database to evaluate the performances of the algorithm, and calculate the mean and the standard deviations. The experiment results show that standard deviations are under the tolerances accepted by expert physicians, and outperform the results obtained by the other algorithms.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.8
• /
• pp.39-46
• /
• 1998

One of the main techniques for diagnosing heart disease is by examining the electrocardiogram(ECG). Many studies on detecting the QRS complex, P, and T waves have been performed because meaningful information is contained in these parameters. However, the earlier detection techniques can not effectively extract those parameters from the ECG that is severely contaminated by noise source. In this paper, we performed the extracting parameters from and recovering the ECG signal using wavelets transform that has recently been applying to various fields.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2006.06a
• /
• pp.89-94
• /
• 2006

In order to increase the signal-to-noise ratio in multi-component seismic data, we developed new polarization filters based on the method of multicomponent complex trace analysis. Unlike the previous polarization filters, the present filters separately compute linear and elliptic components at each time sample using amplitude ratio of horizontal and vertical components of body waves and ellipticity of Rayleigh waves. The polarization filters work ideally even with low S/N data. Application of the filters to both synthetic and real seismic data shows that Rayleigh waves of elliptic motions are effectively eliminated and both P and S waves of linear motions are well separated each other.

• Journal of Biomedical Engineering Research
• /
• v.17 no.2
• /
• pp.235-240
• /
• 1996

The automated ECG diagnostic systems that are odd in hospitals have low performance of P-wave detection when faced with some diseases such as conduction block. So, the purpose of this study was the improvement of detection performance in conduction block which is low in P-wave detection. The first procedure was removal of baseline drift by subtracting the median filtered signal of 0.4 second length from the original signal. Then the algorithm detected R peak and T end point and cancelled the QRS-T complex to get'p prototypes'. Next step was magnification of P prototypes with dispersion and detection of'p candidates'in the magnified signal, and then extraction of contextual information concerned with P-waves. For the last procedure, the CIR was applied to P candidates to confirm P-waves. The rule base consisted of three rules that discriminate and confirm P-waves. This algorithm was evaluated using 500 patient's raw data P-wave detection perFormance was in- creased 6.8% compared with the QRS-T complex cancellation method without application of the rule base.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.125.2-125.2
• /
• 2011

청정 에너지원으로 높은 잠재력을 가지고 있는 가스하이드레이트는 상업적 기술개발이 미확보된 상태이다. 현재 전 세계적으로 가스하이드레이트 개발 및 생산에 관한 연구가 활발히 진행되고 있으며 이에 대한 기초자료로서 가스하이드레이트가 함유된 퇴적층의 물성자료가 필요하다. 특히, 현장 시료에 대한 물성 측정은 향후 가스하이드레이트 개발 및 생산 계획을 수립하는데 있어서 매우 중요하다. 탄성파 측정 결과는 다른 물성 들에 비하여 하이드레이트 함유 시료의 성형과정에 큰 영향을 받는다. 또한 그 외의 실험 경계조건과 취득 자료의 처리 과정에도 매우 민감하게 반응한다. 따라서 측정을 하는 과정은 물론 측정 후 자료의 활용 과정에서 다양히 고려해야 할 점들이 있다. 본 연구에서는 인공 모래를 이용하여 다양한 조건에서 탄성파 속도를 측정한 후 그 결과를 토대로 하여 기존의 연구 결과와 비교하여 음파 측정연구 시 고려해야 할 기술적 사항 들을 정리해 보았다. 실험에 사용된 장비는 고압의 퇴적층을 모사할 수 있는 압력셀과 메탄과 염수 주입에 사용되는 유체 주입장비, 하이드레이트 형성을 위한 온도조절장비, 자료 획득 장비로 구성되어 있다. p파 속도는 음파 송수신장비를 사용하였다.

• The Journal of Engineering Geology
• /
• v.17 no.3
• /
• pp.329-337
• /
• 2007

For seven NX sized borehole models constructed from physical property data for representative geology in Korea, dispersion curves were derived and compared between models having different physical parameters. By comparing and analyzing the dispersion curves obtained from different sources (monopole and dipole) and different borehole sizes (76 mm and 150 mm), dispersion characteristics in sonic log could be understood better, particularly in the case of slim hole sonic log.

• Geophysics and Geophysical Exploration
• /
• v.2 no.4
• /
• pp.209-214
• /
• 1999

A field experiment generating shear waves by trench method was conducted at two places in Taejun area. We were able to separate the P- and S-waves by summing and subtracting the vertical and horizontal component of the data recorded at a three component downhole geophone in the borehole. The analysis of the records revealed that the shear waves were polarized to NS and EW directions. The faster shear waves were polarized to NS direction. The NS direction generally agrees with the dominant joints direction observed from the cores collected from the borehole.

• Journal of the Korean earth science society
• /
• v.27 no.3
• /
• pp.341-347
• /
• 2006

Focal mechanisms were analyzed for the seven earthquakes which occurred in the southwestern part of the Korea Peninsula from 2001 to 2005. Grid searches are performed to fit distributions of P-wave first-motion polarities and SH/P amplitude ratios for each event. The focal mechanism solutions imply that most of the events have strike-slip sense including partially thrust component. The compressional axes of the solutions are predominantly ENE-WSW or NE-SW indirections. This result is similar to the directions of the principal compressional axes for major earthquakes occurred around the Korea Peninsula.