• Title/Summary/Keyword: Spectral studies

Search Result 691, Processing Time 0.028 seconds

Extended Slip-Weakening Model and Inference of Rupture Velocity (Slip-Weakening 모델의 확장과 단층 파열속도의 추정)

  • Choi, Hang;Yoon, Byung-Ick
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.24 no.5
    • /
    • pp.219-232
    • /
    • 2020
  • The slip-weakening model developed by Ohnaka and Yamashita is extended over the breakdown zone by equating the scaling relationships for the breakdown zone and the whole rupture area. For the extension, the study uses the relationship between rupture velocity and radiation efficiency, which was derived in the theory of linear elastic fracture mechanics, and the definition of fmax given in the specific barrier model proposed by Papageorgiou and Aki. The results clearly show that the extended scaling relationship is governed by the ratio of rupture velocity to S wave velocity, and the velocity ratio can be determined by the ratio of characteristic frequencies of a Fourier amplitude spectrum, which are corner frequency, fc, and source-controlled cut-off frequency, fmax, or vice versa. The derived relationship is tested by using the characteristic frequencies extracted from previous studies of more than 130 shallow crustal events (focal depth less than 25 km, MW 3.0~7.5) that occurred in Japan. Under the assumption of a dynamic similarity, the rupture velocity estimated from fmax/fc and the modified integral timescale give quite similar scale-dependence of the rupture area to that given by Kanamori and Anderson. Also, the results for large earthquakes show good agreement to the values from a kinematic inversion in previous studies. The test results also indicate the unavailability of the spectral self-similarity proposed by Aki because of the scale-dependent rupture velocity and the rupture velocity-dependent fmax/fc; however, the results do support the local similarity asserted by Ohnaka. It is also remarkable that the relationship between the rupture velocity and fmax/fc is quite similar to Kolmogorov's hypothesis on a similarity in the theory of isotropic turbulence.

PROPERTIES OF THE SCUBA-2 850㎛ SOURCES IN THE XMM-LSS FIELD

  • Seo, Hyunjong;Jeong, Woong-Seob;Kim, Seong Jin;Pyo, Jeonghyun;Kim, Min Gyu;Ko, Jongwan;Kim, Minjin;Kim, Sam
    • Journal of The Korean Astronomical Society
    • /
    • v.50 no.1
    • /
    • pp.7-20
    • /
    • 2017
  • We carry out the study of $850{\mu}m$ sources in a part of the XMM-LSS field. The $850{\mu}m$ imaging data were obtained by the SCUBA-2 on the James Clerk Maxwell Telescope (JCMT) for three days in July 2015 with an integration time of 6.1 hours, covering a circular area with a radius of 15'. We choose the central area up to a radius of 9'.15 for the study, where the noise distribution is relatively uniform. The root mean square (rms) noise at the center is 2.7 mJy. We identify 17 sources with S/N > 3.5. Differential number count is estimated in flux range between 3.5 and 9.0 mJy after applying various corrections derived by imaging simulations, which is consistent with previous studies. For detailed study on the individual sources, we select three sources with more reliable measurements (S/N > 4.5), and construct their spectral energy distributions (SEDs) from optical to far-infrared band. Redshift distribution of the sources ranges from 0.36 to 3.28, and their physical parameters are extracted using MAGPHYS model, which yield infrared luminosity $L_{IR}=10^{11.3}-10^{13.4}L_{\odot}$, star formation rate $SFR=10^{1.3}-10^{3.2}M_{\odot}yr^{-1}$ and dust temperature $T_D=30-53K$. We investigate the correlation between $L_{IR}$ and $T_D$, which appears to be consistent with previous studies.

Classification Strategies for High Resolution Images of Korean Forests: A Case Study of Namhansansung Provincial Park, Korea

  • Park, Chong-Hwa;Choi, Sang-Il
    • Proceedings of the KSRS Conference
    • /
    • 2002.10a
    • /
    • pp.708-708
    • /
    • 2002
  • Recent developments in sensor technologies have provided remotely sensed data with very high spatial resolution. In order to fully utilize the potential of high resolution images, new image classification strategies are necessary. Unfortunately, the high resolution images increase the spectral within-field variability, and the classification accuracy of traditional methods based on pixel-based classification algorithms such as Maximum-Likelihood method may be decreased (Schiewe 2001). Recent development in Object Oriented Classification based on image segmentation algorithms can be used for the classification of forest patches on rugged terrain of Korea. The objectives of this paper are as follows. First, to compare the pros and cons of image classification methods based on pixel-based and object oriented classification algorithm for the forest patch classification. Landsat ETM+ data and IKONOS data will be used for the classification. Second, to investigate ways to increase classification accuracy of forest patches. Supplemental data such as DTM and Forest Type Map of 1:25,000 scale are used for topographic correction and image segmentation. Third, to propose the best classification strategy for forest patch classification in terms of accuracy and data requirement. The research site for this paper is Namhansansung Provincial Park located at the eastern suburb of Seoul Metropolitan City for its diverse forest patch types and data availability. Both Landsat ETM+ and IKONOS data are used for the classification. Preliminary results can be summarized as follows. First, topographic correction of reflectance is essential for the classification of forest patches on rugged terrain. Second, object oriented classification of IKONOS data enables higher classification accuracy compared to Landsat ETM+ and pixel-based classification. Third, multi-stage segmentation is very useful to investigate landscape ecological aspect of forest communities of Korea.

  • PDF

An Analysis on the Effects of Inter-Device Interference in the ORC-OQ2PSK Based Wireless Personal Area Networks (ORC-OQ2PSK 변조 기반의 근거리 무선통신 시스템에서 기기 간 상호 간섭의 영향 분석)

  • Jeon, Sang Yeop;Kim, Myoung Jin
    • Journal of the Institute of Electronics and Information Engineers
    • /
    • v.53 no.3
    • /
    • pp.3-10
    • /
    • 2016
  • To establish a network environment where multiple wireless personal area networks(WPAN) are simultaneously operating in the same area, we need to consider the effects of inter-device interference. The extent of interference effect from neighboring frequency channel interferer may be different depending on the modulation types that are used for constructing the wireless network. If a modulation scheme with high spectral side lobes is used, the spatial separation between devices plays a major role in determining the amount of interference from neighboring frequency channel interferer. In this paper, we investigate the effect of inter-device interference in the overlapped raised cosine offset quadrature-quadrature phase shift keying (ORC-$OQ^2PSK$) modulation based WPAN. By comparing the results with those of GFSK modulation based WPAN, we verify the feasibility of ORC-$OQ^2PSK$ based WPAN.

Responding to the Spectral Voice of the Outcast: Reading of William Wordsworth's "The Thorn"

  • Kang, Heewon
    • Cross-Cultural Studies
    • /
    • v.36
    • /
    • pp.37-59
    • /
    • 2014
  • William Wordsworth's "The Thorn" revolves around the following questions: Who is Martha? Why does she go to the mountain top and repeat her doleful cry? To these questions, it gives us two different kinds of answers; one derives from the villagers, and the other from the narrator. This essay attempts to examine how the answers exemplify two different critical approaches to the problem of community, using Jacques Lacan's account of sexual difference in his seminar on Encore as a guiding thread of analysis. The important thing to retain here is that sexual difference in Lacan's seminar on Encore does not so much indicate biological determinations as two distinct forms of relating to the other which are intimately bound up with the question of how a community is constructed and maintained. The first form, called "masculine," suggests that it is a radical exception to a community that makes possible the community as a field of totality or sameness; the second form, called "feminine," shows that each of the subjects cannot be regarded as a member of a closed community which is guaranteed by the exceptionality, but as an exception that is radically singular. This in turn leads us to consider the possibility that the masculine form has to do with the villagers' effort to distinguish themselves from Martha and the feminine form with the way in which the narrator confronts and represents her. In the course of his formulation of sexuation graph, Lacan stresses that the masculine side must be supplemented by the feminine side, which allows us to elaborate on why, concerning Martha, the narrator does not just keep the completely different position from the villagers'. This is to say that the villagers' representation of Martha as an exception to the community should be supplemented by the narrator's attempt to tell Martha's story as the villagers do and at the same time to capture something of her enigmatic unrepresentability. Bearing in mind Charles Shepherdson's elaboration of traumatic memory, this essay also tries to clarify how the narrator preserves and even transmits something of Martha's truth that is embodied in her uncontrollable and unassimilable cry.

Derivation of response spectrum compatible non-stationary stochastic processes relying on Monte Carlo-based peak factor estimation

  • Giaralis, Agathoklis;Spanos, Pol D.
    • Earthquakes and Structures
    • /
    • v.3 no.3_4
    • /
    • pp.581-609
    • /
    • 2012
  • In this paper a novel non-iterative approach is proposed to address the problem of deriving non-stationary stochastic processes which are compatible in the mean sense with a given (target) response (uniform hazard) spectrum (UHS) as commonly desired in the aseismic structural design regulated by contemporary codes of practice. This is accomplished by solving a standard over-determined minimization problem in conjunction with appropriate median peak factors. These factors are determined by a plethora of reported new Monte Carlo studies which on their own possess considerable stochastic dynamics merit. In the proposed approach, generation and treatment of samples of the processes individually on a deterministic basis is not required as is the case with the various approaches found in the literature addressing the herein considered task. The applicability and usefulness of the approach is demonstrated by furnishing extensive numerical data associated with the elastic design UHS of the current European (EC8) and the Chinese (GB 50011) aseismic code provisions. Purposely, simple and thus attractive from a practical viewpoint, uniformly modulated processes assuming either the Kanai-Tajimi (K-T) or the Clough-Penzien (C-P) spectral form are employed. The Monte Carlo studies yield damping and duration dependent median peak factor spectra, given in a polynomial form, associated with the first passage problem for UHS compatible K-T and C-P uniformly modulated stochastic processes. Hopefully, the herein derived stochastic processes and median peak factor spectra can be used to facilitate the aseismic design of structures regulated by contemporary code provisions in a Monte Carlo simulation-based or stochastic dynamics-based context of analysis.

Analysis of suppressed thermal conductivity using multiple nanoparticle layers (다중층 나노구조체를 통한 열차단 특성 제어)

  • Tae Ho Noh;Ee Le Shim
    • Journal of Surface Science and Engineering
    • /
    • v.56 no.4
    • /
    • pp.233-242
    • /
    • 2023
  • In recent years, energy-management studies in buildings have proven useful for energy savings. Typically, during heating and cooling, the energy from a given building is lost through its windows. Generally, to block the entry of ultraviolet (UV) and infrared (IR) rays, thin films of deposited metals or metal oxides are used, and the blocking of UV and IR rays by these thin films depends on the materials deposited on them. Therefore, by controlling the thicknesses and densities of the thin films, improving the transmittance of visible light and the blocking of heat rays such as UV and IR may be possible. Such improvements can be realized not only by changing the two-dimensional thin films but also by altering the zero-dimensional (0-D) nanostructures deposited on the films. In this study, 0-D nanoparticles were synthesized using a sol -gel procedure. The synthesized nanoparticles were deposited as deep coatings on polymer and glass substrates. Through spectral analysis in the UV-visible (vis) region, thin-film layers of deposited zinc oxide nanoparticles blocked >95 % of UV rays. For high transmittance in the visible-light region and low transmittance in the IR and UV regions, hybrid multiple layers of silica nanoparticles, zinc oxide particles, and fluorine-doped tin oxide nanoparticles were formed on glass and polymer substrates. Spectrophotometry in the UV-vis-near-IR regions revealed that the substrates prevented heat loss well. The glass and polymer substrates achieved transmittance values of 80 % in the visible-light region, 50 % to 60 % in the IR region, and 90 % in the UV region.

An Evaluation of Size-Resolved Cloud Microphysics Scheme Numerics for Use with Radar Observations. Part II: Condensation and Evaporation

  • Hyunho Lee;Ann M. Fridlind;Andrew S. Ackerman
    • Korean Journal of the Atmospheric Sciences
    • /
    • v.78 no.5
    • /
    • pp.1629-1645
    • /
    • 2021
  • Accurate numerical modeling of clouds and precipitation is essential for weather forecasting and climate change research. While size-resolved (bin) cloud microphysics models predict particle size distributions without imposing shapes, results are subject to artificial size distribution broadening owing to numerical diffusion associated with various processes. Whereas Part I of this study addressed collision-coalescence, here we investigate numerical diffusion that occurs in solving condensation and evaporation. In a parcel model framework, all of the numerical schemes examined converge to one solution of condensation and evaporation as the mass grid is refined, and the advection-based schemes are recommended over the reassigning schemes. Including Eulerian vertical advection in a column limits the convergence to some extent, but that limitation occurs at a sufficiently fine mass grid, and the number of iterations in solving vertical advection should be minimized to reduce numerical diffusion. Insubstantial numerical diffusion in solving condensation can be amplified if collision-coalescence is also active, which in turn can be substantially diminished if turbulence effects on collision are incorporated. Large-eddy simulations of a drizzling stratocumulus field reveal that changes in moments of Doppler spectra obtained using different mass grids are consistent with those obtained from the simplified framework, and that spectral moments obtained using a mass grid designed to effectively reduce numerical diffusion are generally closer to observations. Notable differences between the simulations and observations still exist, and our results suggest a need to consider whether factors other than numerical diffusion in the fundamental process schemes employed can cause such differences.

Drone-based Vegetation Index Analysis Considering Vegetation Vitality (식생 활력도를 고려한 드론 기반의 식생지수 분석)

  • CHO, Sang-Ho;LEE, Geun-Sang;HWANG, Jee-Wook
    • Journal of the Korean Association of Geographic Information Studies
    • /
    • v.23 no.2
    • /
    • pp.21-35
    • /
    • 2020
  • Vegetation information is a very important factor used in various fields such as urban planning, landscaping, water resources, and the environment. Vegetation varies according to canopy density or chlorophyll content, but vegetation vitality is not considered when classifying vegetation areas in previous studies. In this study, in order to satisfy various applied studies, a study was conducted to set a threshold value of vegetation index considering vegetation vitality. First, an eBee fixed-wing drone was equipped with a multi-spectral camera to construct optical and near-infrared orthomosaic images. Then, GIS calculation was performed for each orthomosaic image to calculate the NDVI, GNDVI, SAVI, and MSAVI vegetation index. In addition, the vegetation position of the target site was investigated through VRS survey, and the accuracy of each vegetation index was evaluated using vegetation vitality. As a result, the scenario in which the vegetation vitality point was selected as the vegetation area was higher in the classification accuracy of the vegetation index than the scenario in which the vegetation vitality point was slightly insufficient. In addition, the Kappa coefficient for each vegetation index calculated by overlapping with each site survey point was used to select the best threshold value of vegetation index for classifying vegetation by scenario. Therefore, the evaluation of vegetation index accuracy considering the vegetation vitality suggested in this study is expected to provide useful information for decision-making support in various business fields such as city planning in the future.

Mineralogical Studies on Sulfide Ore Species of the Tong Myeong Tungsten Deposits (동명중석광산산(東明重石鑛山産) 유화광물(硫化鑛物)의 광물학적(鑛物學的) 연구(硏究))

  • Lee, Pyeong-Koo;So, Chil-Sup;Kim, Se-Hyun;Yun, Seong-Taek;Kim, Moon-Young
    • Economic and Environmental Geology
    • /
    • v.19 no.spc
    • /
    • pp.207-226
    • /
    • 1986
  • The skarn type tungsten deposits in Jechon area are developed in the contact aureole of Jurassic granodiorite and lower Paleozoic limestone beds. The Tong Myeong mine contains scheelitebearing skarns found at and near the contacts between crystalline limestone and hornfels. Although the skarns are heterogeneous, there are clear patterns in the preferred associations and nonassociations of minerals on all scales. The skarn show a zonal arrangement from limestone to hydrothermal vein as follow: wollastonite skarn, clinopyroxene skarn, clinopyroxene-garnet skarn, garnet skarn, and vesuvianite skarn. Scheelite, abundant in all skarn units except wollastonite skarn and also in quartz veins near orebodies, is everywhere strongly correlated with pyrrhotite. It is implied that it was a stable phase throughout the evolution of the zoned skarns, at least in pyrrhotite.forming environments. Deposition of scheelite was probably widely caused by increasing $a_{Ca^{2+}}$ in the fluid, resulting from associated and interrelated reactions: $FeCl_2\;aq+H_2S\;aq{\rightarrow}FeS+2H^{+}+2Cl^-$; and $CaCO_3+2H^+{\rightarrow}Ca^{+2}+H_2CO_3$. The spectral reflection powers of nine sulfide species were studied, for three mineralization stage. The shapes and characteristics of the spectral reflectivity profiles are significant in their control of other optical properties. The characteristics of the Vickers microhardness and the optical symmetry for the minerals studied are discussed. Broad radicle groupings of the sulfides can be made with regard to the reflectivity-microhardness values.

  • PDF