• Geophysics and Geophysical Exploration
• /
• v.11 no.2
• /
• pp.137-147
• /
• 2008

Fault rupture directivity of the Odaesan earthquake, which was inferred to be the main cause of the high PGAvalue (> 0.1 g) unusually observed at the near-source region, was analyzed by using the data from the nearby (R < 100 km) dense seismic stations. The Boatwright's method (2007) was adopted for this purpose in which the azimuth and takeoff angle of the unilateral rupture directivity function could be estimated based on the relative peak ground-motions of seismic stations resulting from the nature of the rupture directivity. In this study, the approximate values of the relative peak ground-motions was derived from the difference between the log residuals of the point-source spectral model (Boore, 2003) for the main and secondary events based on the Random Vibration Theory. In this derivation, the spectral difference for a frequency range between the source corner frequencies of main and secondary events was considered to reflect only the effect of the fault directivity. The inversion result of the model parameters for the fault directivity function showed that the fault-plane of NWW-SEE direction dipping steeply to the North with high rupture velocity near upward in SE direction is responsible for the observed high level of ground-motion at the near-source region.

• Journal of Biosystems Engineering
• /
• v.24 no.2
• /
• pp.115-122
• /
• 1999

Because of their small mass, volume, solid state construction and long life, light-emitting diodes(LEDs) hold promises as a lighting source for intensive plant production system. Spectral characteristics and light intensity of LEDs were tested to investigate their feasibility as artificial lighting sources for growth and morphogenesis control in transplant production system. Blue, green, and red LEDs had a peak-emission wavelength at 442nm, 522nm, and 673nm, respectively. Their half width defined as the difference between upper and lower wavelength in the intensity equivalent to 50% of the maximum intensity showed 26nm, 41nm, and 74nm, respectively. Photosynthetic photon flux(PPE) at the distance of 9cm under the LEDs array was measured as $235{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ for red, $109{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ for green, and $75{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ for blue LEDs. At the same distance, green LEDs had the illuminance of 13,0001x, nine to ten times higher than those of red and blue LEDs. Red, green, and blue LEDs at a distance of 9cm had the irradiance of $46W{\cdot}m^{-2},\;19W{\cdot}m^{-2},\;8W{\cdot}m^{-2}$, respectively. Light intensity of blue, green, and red LEDs increased linearly in proportion to the magnitude of the current applied to the operating circuit. Thus the light intensity of LEDs was controlled by the applied current in operating circuit.

• Korean Journal of Medicinal Crop Science
• /
• v.14 no.2
• /
• pp.113-116
• /
• 2006

This study was carried out to investigate spectral irradiance characteristics of blue, yellow, and blue-black colored polyethylene (PE) shading net and the effect on growth characteristics and yield in ginseng seedling. The spectral irradiance $({\mu}mol/m^2/s/nm)$ showed the peak at 498 nm in both of blue and blue-black PE shading net, and 606 nm under yellow PE one. The intensity of blue light in blue shading was more strong than that of blue-black shading, control. Blue shading was increased by 17% and 23% in accumulated quantum for daytime, $0.5^{\circ}C and $0.2^{\circ}C$ in maximum temperature on June 2 than that of yellow and blue-black shading, respectively, but heat injury ratio of the former was lower than that of the latter. Chlorophyll content and stem length in blue shading were decreased more significantly than those of yellow and blue-black shading. The specific leaf weight was higher under blue and yellow shading than that of blue-black shading. Ginseng seedling harvested in blue shading was increased by $13{\sim}17%$ in the number of root, and $17{\sim}20%$ in root weight per $m^ 2 compared to yellow and blue-black shading owing to the increase of survived plant, and the decrease of specific leaf weight, heat injury ratio, and stem length.

• Applied Biological Chemistry
• /
• v.25 no.4
• /
• pp.224-231
• /
• 1982

${\alpha}-Tocopherol$ was found to be a fluorescent probe in determination of the phasetransition temperature of liposome. Since this was a discovery of a new aspect of ${\alpha}-tocopherol$ as an important biochemical molecule, its molecular spectroscopic characterization was carried out in order to obtain some informations on its spectral and, structural properties in various media, anticipating that the compound may entertain a wide applications in biochemical systems as a spectroscopic probe. Two species of α${\alpha}-tocopherol$, monomer and dimer, were found to exist in organic media, especially in solvents of nonhydrogen bonding ability. Monomer with maximum UV-absorption around $(291{\sim}294nm)$ is highly fluorescent, while dimer which is formed by intermolecular hydrogen bonds and absorbes with spectral peak at 298nm is nonfluorescent. ${\alpha}-tocopherol$ incorporated to liposome exhibits emission property quite different from that in various organic media showing broad and red-shifted fluorescence excitation and emission spectra. This spectral abnormality is to be interpreted to arise from chromanolate-type ion, H-dissociated ${\alpha}-tocopherol$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.8
• /
• pp.770-775
• /
• 2008

Autonomic nervous system of the anesthetized patients can be influenced by the many kinds of stimulations such as intubation, surgical incision and so on. The changes of the heart rates and blood pressures are surrogates of responses of the autonomic system to the external stimulations. Recently, the power spectral analysis of the heart rate variability (HRV) made it easy to know the fractions and changes of sympathetic and parasympathetic autonomic systems. In this study, the changes of pulse transit time, one of the response of vessels to stimulations, was investigated in relation to the HRV. Ten patients were examined and average age is 22.5 $\pm$ 11.04, average weight is 63 $\pm$ 14.4 kg. The patients were anesthetized only by sevoflurane inhalation. Pulse transit time is determined by calculating the difference of the time between the R peak of ECG and the characteristic point of the plethysmography. Power spectral density (PSD) of the HRV was achieved in the frequency of 0.04-0.15 (LF) and 0.15-0.4 (HF). Compared to preanesthetic period the values of LF and LF/HF ratio of HRV were decreased (p<0.05). HF and PTT was increased in anesthetic state with sevoflurane. Otherwise, after intubation, the HF was decreased and LF, LF/HF ratio and PTT were increased. PSD of the HRV is well-known for the index of the autonomic nervous activity. Not only HRV but PTT analysis also is a useful index reflecting the autonomic responses to various stimulations. And this analysis is useful in bed side monitoring because the calculating method is simple and it takes shorter processing time compared to the HRV analysis.

• Proceedings of the Korean Society for Cognitive Science Conference
• /
• 2010.05a
• /
• pp.37-41
• /
• 2010

The previous investigations of electroencephalogram (EEG) activity in the memory retrieval tasks demonstrated that event-related potentials (ERP) during recollection showed different durations and the peak levels from those without recollection. However, it has been unknown that recollection in memory retrieval also modulates high-frequency brain rhythms as well as establishes large-scale synchronization across different cortical areas. In this study, we examined the spectral components of the EEG signals, especially the gamma bands (20-80Hz), measured during the memory retrieval tasks. Specifically, we focused on two major spectral components: first, we evaluated the temporal patterns of the power spectral density before and after the onset of the memory retrieval task; second, we estimated phase synchrony between all possible pairs of EEG channels to evaluate large-scale synchronization. Fourteen healthy subjects performed the memory retrieval task in the virtual reality environment where they selected whether or not t he present item was seen in the previous training period. When the subjects viewed the unseen items, the middle gamma power (40-60Hz) appeared to increase 200-500ms after stimulus onset while the low gamma power (20Hz) was suppressed all the way through the post-stimulus period 150ms after onset. The degree of phase synchronization in this low gamma level, however, increased when the subjects fetched the item from memory. This suggests that phase synchrony analysis might reveal different aspects of the memory retrieval process than the gamma power, providing additional information to the inference on the brain dynamics during memory retrieval.

• Korean Journal of Materials Research
• /
• v.11 no.4
• /
• pp.247-250
• /
• 2001

We have fabricated and evaluated a new Si pin photodiode for red light detection with the web patterned $p^{+}$ -shallow diffused region in the light absorbing area. From the measurements of electro-optical characteristics under the bias of -5V, the junction capacitance of 4pF and the dark current of 235pA were obtained. When the 1.6㎼ optical power with peak wavelength of 670nm was incident on the device, the optical signal current of 0.48$\mu\textrm{A}$ and the responsivity of 0.30A/W were obtained. The fabricated device showed the improved sensitivity compared to the conventional circular type device and the maximum spectral response in a spectrum of 670~700nm. The web-patterned Si photodiode can be expected to have the good discrimination characteristics between digital signals in the application of red light optics.

• Geomechanics and Engineering
• /
• v.20 no.2
• /
• pp.131-146
• /
• 2020

Evaluation of earthquake impacts in settlements with a high risk of earthquake occurrence is important for the determination of site-specific dynamic soil parameters and earthquake-resistant structural planning. In this study, dynamic soil properties of Karliova (Bingol) city center, located near to the intersection point of the North Anatolian Fault Zone and the East Anatolian Fault Zone and therefore having a high earthquake risk, were investigated by one-dimensional equivalent linear site response analysis. From ground response analyses, peak ground acceleration, predominant site period, 0.2-sec and 1-sec spectral accelerations and soil amplification maps of the study area were obtained for both near-field and far-field earthquake effects. The average acceleration spectrum obtained from analysis, for a near-field earthquake scenario, was found to exceed the design spectra of the Turkish Earthquake Code and Eurocode 8. Yet, the average acceleration spectrum was found to remain below the respective design spectra of the two codes for the far-field earthquake scenario. According to both near- and far-field earthquake scenarios in the study area, the low-rise buildings with low modal vibration durations are expected to be exposed to high spectral acceleration values and high-rise buildings with high modal vibration durations will be exposed to lower spectral accelerations. While high amplification ratios are observed in the north of the study area for the near-distance earthquake scenario, high amplification ratios are observed in the south of the study area for the long-distance earthquake scenario.

• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.1
• /
• pp.88.2-88.2
• /
• 2011

The far-ultraviolet (FUV) continuum and spectral images of C IV and H2 emission lines for the region of Orion-Eridanus Superbubble (OES) are hereby presented and compared with the maps obtained in other wavelengths. While the region shows complex structures, consisting of hot gases and cold dust, a close examination reveals that the FUV emission in this region can be understood reasonably as the result of their interactions. We confirm the origin of most diffuse FUV continuum to be starlight scattered by dust, but we also find that the ionized gas also contributes 50-70% of the total FUV intensity in the regions of H_alpha arcs. We note the bright diffuse FUV continuum in the eastern part of the northern dust-rich region, and attribute it to the bright early-type stars more abundant in this region than in the west as the amount of dust itself does not seem to be much different across 'arc A' that separates the two regions. In addition, two P Cygni-type stars are identified in this eastern region and their peculiar spectral profiles around the C IV emission line are anifested in the scattered diffuse spectrum. Besides this, the C IV emission is generally enhanced at the boundaries of the hot X-ray cavities where thin dust regions are located, confirming the thermal interface nature of the origin of this cooling emission line. The morphology of the H2 emission shows a general correlation with dust extinction features but its intensity peaks are rather located in thin dust areas, off the peak dust regions. Furthermore, H2 emission is seen to be weak in the arc A region though the arc passes through the center of the dust-rich area. Hence, the H2 emission and dust features, together with those of X-ray and ion lines emissions, show stratified structure of arc A quite well, again confirming its thermal interface nature.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.11 no.1
• /
• pp.20-33
• /
• 1999

The evolution of deep-sea waves is driven by energy input from wind, nonlinear energy transfer between wave components, and dissipation through whitecaps. A comparative study was implemented by the use of two wave models in which only the computation methods of nonlinear wave-wave interactions are different from each other. It was reaffirmed that the nonlinear interaction plays a central role in such phenomena that occurred during the spectral growth of wind-seas as down-shift of the spectral peak frequency, overshoot, undershoot, and formation of self-similar spectrum. Specifically, the directional distribution at high frequencies develops into bimodal form, which is attributed to the nonlinear interactions. As saturation stage is reached, spectral density at high frequencies becomes proportional to negative 4 power to the frequency. Perturbations introduced into the spectrum quickly vanished through the actions of the self-similar mechanism. Thus, the nonlinear transfer has important contribution to the stability of numerical ocean wave models.