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Characters of Perturbation in Earth's Spin Rotation
나성호,곽영희,Na, Sung-Ho,Kwak, Younghee 한국천문학회 2012 天文學會報 Vol.37 No.2
From the most recent dataset of the earth's spin rotation, we separate different frequency components of its perturbation and analyze their characteristics. Both changes of the earth's spin and pole position are considered.
단보 : “지구 대기가 지구 기준계에 미치는 영향: 기존 모델 분석”에 대한 증보
나성호 ( Sung Ho Na ),조정호 ( Jungho Cho ) 한국지구물리·물리탐사학회 2016 지구물리와 물리탐사 Vol.19 No.1
The Earth’s atmosphere exerts loading pressure to induce small crustal displacement and also leads small perturbation in the Earth’s pole position and the spinning rate. Formerly we reported a summary of related models and showed one example for a hypothetical typhoon passing Korean peninsula. In estimation of the atmospheric loading effect of typhoon, the Korea-Japan Sea can be treated as an ‘isolated lake’ rather than an open ocean. This alternative case is considered here as supplement. Typhoons usually migrate considerable distance, and one more calculation about the corresponding perturbation on the Earth’s rotation is added here. Finally we hereby correct minor errors in the horizontal displacement arrow illustrations and a blunder in the text - one wrong index among its equations.
삼각망에서 변형률산출의 신뢰도와 적용례; GPS로 관측된 2011 토호쿠지진에 의한 한반도 변형
나성호 ( Sung Ho Na ),정태웅 ( Tae Woong Chung ),최병규 ( Byung Kyu Choi ),유성문 ( Sung Moon Yoo ) 한국지구물리·물리탐사학회 2013 지구물리와 물리탐사 Vol.16 No.4
A stable procedure is presented to attain most probable and unbiased estimate of principal strain, rotation, and dilatation for 2-dimensional geodetic data on triangular network. The proper network size should be chosen carefully, because the errors of these estimates of strain tensor and other associated observables grow inversely proportional to the area of station triangle. As a case study, the deformation observables for the GPS-monitored co-seismic displacement in Korea due to the 2011 Tohoku-Oki earthquake were attained accordingly.
나성호 ( Sung Ho Na ),신영홍 ( Young Hong Shin ),백정호 ( Jeong Ho Baek ) 한국지구물리·물리탐사학회 2011 지구물리와 물리탐사 Vol.14 No.2
The largest terms in the solid Earth body tide calculation are second degree spherical harmonic components due to the moon or the sun, and they compose about 98 percent of total contribution. Each degree harmonics of the tidal perturbation should be evaluated through multiplication with distinct Love numbers or their combinations. Correct evaluation of these terms in gravity tide is considered with re-calculated Love numbers. Frequency dependence of Love numbers for spherical harmonic tide upon the order number is discussed. Tidal displacement and tidally induced deviation of the vertical are also evaluated. Essential concepts underlying the body tide calculation are briefly summarized.
지구 대기가 지구 기준계에 미치는 영향: 기존 모델 분석
나성호 ( Sung-ho Na ),조정호 ( Jungho Cho ) 한국지구물리·물리탐사학회 2015 지구물리와 물리탐사 Vol.18 No.3
Displacement of the Earth’s surface due to atmospheric loading has been recognized since a century years ago, and its accurate estimation is required in present day geodesy and surveying, particularly in space geodesy. Atmospheric load deformation in continental region can readily be calculated with the given atmospheric pressure field and the load Green’s function, and, in near coastal area, approximate model is used for the calculation. The changes in the Earth’s atmospheric circulation and the seasonal variation of atmospheric pressure on two hemispheres of the Earth are the each main causes of variation of the Earth’s spin angular velocity and polar motion respectively. Wind and atmospheric pressure do the major role in other periodic and non-periodic perturbations of the positions in the Earth’s reference frame and variations in the Earth’s spin rotational state. In this reviewing study, the developments of related theories and models are summarized along with brief description of phenomena, and the geodetic perturbing effects of a hypothetical typhoon passing Korea are shown as an example. Finally related existing problems and further necessary studies are discussed in general.
단보 : “구면부분지역에서 퍼텐셜마당의 상향연속”의 하향연속 확장적용
나성호 ( Sung Ho Na ),정태웅 ( Tae Woong Chung ),신영홍 ( Young Hong Shin ) 한국지구물리·물리탐사학회 2013 지구물리와 물리탐사 Vol.16 No.1
We formerly reported a new method for the upward continuation of potential field on spherical patch area including Earth`s curvature, which has been neglected in most studies on rectangular area with flat Earth assumption. This new method is applicable to downward continuation as well by only assigning corresponding value for the ratio of two radii; r2/r1, i.e., target radius r2 versus datum radius r1. In addition, the inherent problem of this method due to spherical surface geometry is described, and its one possible remedy is given.
이방성 층상구조에 대한 전위와 전기장 및 전기비저항탐사 계산 연구
나성호 ( Sung-ho Na ),김형수 ( Hyoung-soo Kim ) 한국지구물리·물리탐사학회 2021 지구물리와 물리탐사 Vol.24 No.3
We followed and extended the algorithm originally made by Das (1995) to calculate the electric potential and field induced by electric current in arbitrary anisotropic layered structure. We confirmed all the theoretical contents and coded the corresponding program to acquire the electric potential and field. Further we extended to forward estimation of apparent resistivity to be attained by electrical resistivity survey on anisotropic layered structure with differing the electrode spacing and azimuth of anisotropy. The effects of anisotropy were reviewed by considering some examples.
나성호 ( Sung Ho Na ),정태웅 ( Tae Woong Chung ),신영홍 ( Young Hong Shin ) 한국지구물리·물리탐사학회 2012 지구물리와 물리탐사 Vol.15 No.4
Two dimensional Fourier transform can be used for the upward continuation of gravity or magnetic field data acquired at given altitude over a rectangular area. Earth`s curvature is often neglected in most potential field continuations, however, it should be considered over several hundred kilometer field area. In this study, we developed a new method retaining terms of Earth`s curvature to better perform the continuation of potential field on spherical patch area.