• Proceedings of the KSEEG Conference
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• 2003.04a
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• pp.139-142
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• 2003

지구물리학적 연구에서 있어서 가장 중요한 목적 중의 하나는 지각과 상부 맨틀의 상세한 구조를 규명하는 것이다. 3성분의 지진기록을 이용하여 관측소 하부의 지각구조를 연구하는 몇 가지 방법들이 개발되었으며, 수신함수분석(receiver function analysis)이 가장 널리 사용되고 있다 (Phinney, 1964: Burdick and Langston, 1977: Owens and Crosson, 1988). 수신함수는 원거리 지진의 P파와 관측소 하부의 Moho면에서 전환된 Ps 전환파를 이용하여 관측소 하부의 지각구조를 계산하는 것이다. (중략)

• Economic and Environmental Geology
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• v.31 no.1
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• pp.21-29
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• 1998

Broadband receiver functions are developed from teleseismic P waveforms recorded at Wonju (KSRS), Inchon (IRIS), and Pohang (PHN), and are analyzed to examine the crustal structure beneath the three stations. The teleseismic receiver functions are inverted in the time domain to the vertical P wave velocity structure beneath the stations. Clear P-to-S converted phases from the Moho interface are observed in teleseismic seismograms recorded at the three stations. We estimated the crustal velocity structures beneath the stations using the receiver function inversion. The general features of inversion results are as follows: (1) For Pohang station, there is a high velocity gradient at a 4~5 km deep for SE and NW back azimuth and a low velocity zone at around 10 km deep. The Moho depth is 28 km for NW direction. (2) The shallow crustal structure beneath Wonju station is somewhat complex and there is a high-velocity zone ($V_p{\simeq}6.8km/sec$) at 3 to 4 km deep. The average crustal thickness is 33 km, and a transition zone exists at a 30~33 km deep of lower crust, of which velocity is abruptly changed 6.4 to 7.9 km/sec. (3) For Inchon station, the crustal velocity gradient monotonously increases up to the Moho discontinuity and the velocity is abruptly changed from 6.2 km/sec to 7.9 km/sec at 29 km deep.

• Geophysics and Geophysical Exploration
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• v.17 no.2
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• pp.66-73
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• 2014

To estimate the shear-velocity ($v_s$) structure beneath the WIZ station on White Island in New Zealand, we applied receiver function (RF) inversion and H-${\kappa}$ stacking methods to 362 teleseismic events (Mw > 5.5) recorded during April 20, 2007 to September 6, 2013. Using 71 RFs with errors less than 20% after 200 iterative computations, we determined that the depth to Moho of $v_s$ = 4.35 km/s is $24{\pm}1km$ within a 15 km radius of the station. In an 1-d $v_s$ model derived by RF inversions, a 4-km thick low-velocity layer (LVL) at depths of 18 ~ 22 km was identified in the lower crust. This LVL, which is 0.15 km/s slower than the rocks above and below it, may indicate the presence of a deep magma reservoir. The H-${\kappa}$ stacking method yielded an estimate of the depth to the Moho of 24.5 km, which agrees well with the depth determined by RF inversions. The low $v_p/v_s$ ratio of 1.64 may be due to the presence of gas-filled rock or hot crystallizing magma.

• Review of KIISC
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• v.32 no.1
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• pp.31-38
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• 2022

함수암호(functional encryption)는 프라이버시를 보호하면서 암호화된 데이터에 대한 연산을 수행할 수 있는 진화된 형태의 암호 기술이다. 비밀키를 가진 수신자에게 평문을 전부 제공하는 기존의 암호와 달리, 함수암호는 특정 연산에 대응하는 비밀키를 가진 수신자에게 평문에 대한 연산 결과만을 제공하기 때문에 데이터에 대한 유연한(fine-grained) 접근 제어가 가능하다. 인공지능과 같은 4차 산업혁명 시대의 대표 기술들은 데이터의 활용을 기반으로 하지만 이 과정에서 데이터 노출로 인한 사용자 프라이버시 침해 문제가 발생할 수 있다. 함수암호는 이러한 문제를 해결할 수 있는 기술로써, 프라이버시 보호와 데이터 경제 활성화를 위한 기반 기술로 활용될 수 있다. 본 논문에서는 함수암호 기술에 대한 개념을 설명하고 관련 연구 동향을 소개한다.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.61-70
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• 2006

3-D S-wave velocity model in the southern Korean Peninsula is investigated by using the joint inversion of receiver functions and surface-wave dispersion. A peninsula average Rayleigh-wave phase velocity in the 10-150 seconds range and tomographic estimates of the Rayleigh and Love wave group velocities in the 0.5-20 seconds period range determined using a $12.5{\times}12.5\;km$ grid for the southern part of the peninsula are used for the inversion. Receiver functions were determined from broadband (STS-2), short-period (SS-1) and acceleration (Episensor) channels of 95 stations. The dense distribution of the stations in the Peninsula permits us to examine the 3-D crustal structure in detail. The inversion result shows the variation and characteristics of S-wave velocity in the crust and upper mantle of the southern Korean Peninsula very well.

• Geophysics and Geophysical Exploration
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• v.18 no.1
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• pp.1-8
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• 2015

To estimate the shear-wave velocity (${\nu}_s$ beneath the OTVZ seismic station on Ngauruhoe volcano in New Zealand, we calculated receiver functions (RFs) using 127 teleseismic data ($Mw{\geq}5.5$) with high signal-to-noise ratios recorded during November 11, 2011 to September 11, 2013. The genetic inversion algorithms was applied to 21 RFs calculated by the iterative time-domain deconvolution method. In the 1-D ${\nu}_s$ model derived by the inversion, the Moho is observed at a 14 km depth, marked by a ${\nu}_s$ transition from 3.7 km/s to 4.7 km/s. The average ${\nu}_s$ of the overlying crust is 3.4 km/s, and the average ${\nu}_s$ of a greater than 9-km thick low-velocity layer (LVL) in the lower crust is 3.1 km/s. The LVL becomes thinner with increasing distance from the station. Another LVL thicker than 10 km with ${\nu}_s$ less than 4.3 km/s is found in the upper mantle. Those LVLs in the lower crust and the upper mantle and the relatively thin crust might be related to the magma activity caused by the subducting Pacific plate.

• Geophysics and Geophysical Exploration
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• v.15 no.1
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• pp.8-15
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• 2012

To estimate the S-wave velocity structure beneath the KS31 broad-band station in Wonju, Korea, we used $H-{\kappa}$ stacking and joint inversion of receiver functions and surface-wave dispersion curves derived from 297 teleseismic events (Mw > 5.5) recorded during the period between 2002 and 2009. We thereby determined that the average depth to a nearly flat Moho is $32.4{\pm}0.5\;km$ within tens of kilometer radius of the seismic station. For the crust at this location, we estimate an average shear-wave velocity of 3.69 km/s and a ratio of P- to S-wave velocities, $V_p/V_s$, of $1.72{\pm}0.04$, as is typical for continental crust. A negative phase in the receiver functions at 1 s indicates the presence of a shearwave low velocity layer in a depth interval of 10 to 18 km in the upper crust beneath the KS31 station.

• 한국지구물리탐사학회:학술대회논문집
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• 2004.06a
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• pp.238-246
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• 2004

• 한국지구물리탐사학회:학술대회논문집
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• 2011.10a
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• pp.131-132
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• 2011

• Geophysics and Geophysical Exploration
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• v.10 no.1
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• pp.19-28
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• 2007

In this study, we propose a joint inversion method, using genetic algorithms, to estimate an S-wave velocity structure for deep sedimentary layers from receiver functions and surface-wave phase velocity observed at several sites. The method takes layer continuity over a target area into consideration by assuming that each layer has uniform physical properties, especially an S-wave velocity, at all the sites in a target area in order to invert datasets acquired at different sites simultaneously. Numerical experiments with synthetic data indicate that the proposed method is effective in reducing uncertainty in deep structure parameters when modelling only surface-wave dispersion data over a limited period range. We then apply the method to receiver functions derived from earthquake records at one site and two datasets of Rayleigh-wave phase velocity obtained from microtremor array surveys performed in central Tokyo, Japan. The estimated subsurface structure is in good agreement with the results of previous seismic refraction surveys and deep borehole data. We also conclude that the proposed method can provide a more accurate and reliable model than individual inversions of either receiver function data only or surface-wave dispersion data only.