역시간 구조 보정을 이용한 지질구조 해석

고진석,서동우 조선대학교 에너지.자원신기술연구소 2000 에너지·자원신기술연구소 논문지 Vol.22 No.1

Conventional wave equation migrations correct the reflector shape using extrapolation and imaging with initial boundary condition on the surface. The wave equation migration using paraxial approximation can not migrate multiples, S wave, and common shot gather data. One way to complete this defect is to use a full waveform inversion technique which needs much computing time in calculating the wave fields and partial derivative seismograms for each model guessed iteratively. In this thesis two new methods are studied which image the subsurface by the partial derivatives, with respect to layer parameters, of the cross-correlation of observed and model data. The one method is to image the subsurface by inner product, cross-correlation, of the observed data and partial derivative seismograms which are calculated from the virtual sources determined from synthetic seismogram for a guessed model and partial derivatives of the guessed model with respect to velocity. The other method is to image the subsurface by crossprrelation of the virtual sources and the back propagated wave fields calculated from the observed data. The cross-correlation in each of the two method has large values at layer interfaces even if the initially guessed model is quite different from true model. Therefore, no iterative modification of the guessed model is necessary by this methods. This fact gains an advantage over the migration using iterative ful! waveform inversion.

전기비저항 탐사를 이용한 수리시설물의 안정성 연구

고진석,모상칠 조선대학교 에너지.자원신기술연구소 2004 에너지·자원신기술연구소 논문지 Vol.26 No.2

The resistivity of clay section subsisting in a dam has changed because of water content or degree of compaction as it goes so far as to transform and be carried away for processing the deterioration with time-passing. This study contemplates the structural information related to the transformation of subsurface and grasp the inhomogeneity in the dam operating a resistivity survey regarding whether the stability of clay in a dam is kernel of a stability of a whole dam and seepage. As a result, a report is confirmed a horizontal alternation about a resistivity, the rapid dispersion on electromagnetic wave and aspects of attenuation at clay section near depth 3~6m, which shows there exists a horizontal anomaly from a central deep on upstream slope to a line of saturation on downstream slope and also it shows the clay section on downstream is remarkably inhomogeneous according as this study finds a diffusion of a low resistivity within the preschbed depth.

수직 밀도 구배를 가진 지질 구조에서의 중력 자료 역산과 목적함수 특성

고진석,서동우,강추원 조선대학교 동력자원연구소 1995 動力資源硏究所誌 Vol.17 No.2

This thesis presents some results numerical experiments on the 2-D inversion of gravity data obtained in the structure models. The structure models are represented by their cross-sections of N-sided polygons with density contrasts which are varying with depths. Gravity data for the structure models are calculated by theoretical formulas and are regarded as the true observed gravity data. The inversion of the true data each model is performed by the damped least squares inversion method. Results of this study show that the subsurface interface and the surface density contrast of each model are accurately determined when the vertical density gradient is known. In cast where the density gradient is unknown, the inversion gives incorrect results. But the shape and the density gradient of the model are determined correctly when the surface density contrast is known as is the usual case. Correct inversion can be generally guaranteed by the following conditions; The initial assumption of unknown parameters such as the number of a polygon's vertices should be made reasonably. A way to estimate a reasonable initial model is to compare the objective function values obtained from various unknown parameters and to select the parameters corresponding to the minimum value.

제주도 광령리 지역의 지하 이상(異常)물체의 GPR탐사 연구

고진석,모상칠 조선대학교 에너지.자원신기술연구소 2003 에너지·자원신기술연구소 논문지 Vol.25 No.2

Ground-penetrating radar(GPR) has proved to be an excellent technique for shallow exploration of surface body. In the Jeju island, however, successful application of GPR has been limited owing to the underground anomaly body. There are settings within this region where GPR offers the possibility of rapid, cost-effective subsurface exploration. This paper describes reconnaissance exploration at several locations on the Kwangrung province. The typical profile has appearance and is composed of numerous reflectors with hyperbolas produced by anomaly body. Continuous reflectors that may indicate contacts between buried anomaly body or cavity. Besides demonstrating the feasibility of GPR in this province, we also attempt to show how complex structure affect GPR results.

지하매설물 탐지를 위한 GPR탐사 자료처리 연구

고진석,모상칠 조선대학교 생산기술연구소 2003 生産技術硏究 Vol.25 No.2

GPR exploration is widely used for the application to various fields. Thus, the factors which control the characteristics of GPR response to different subsurface conditions must be understood. A controlled test site was constructed to study the factors. Artificial barriers were buried containing irregular-sized pipes. We treated the data in several ways to find out a better method for processing the data from the site. In this study, We showed that proper frequency selection and data processing were necessary for successful analyses.

심부 지층 모형의 중력 자료 역산

고진석,서동우 조선대학교 동력자원연구소 1994 動力資源硏究所誌 Vol.16 No.2

Gravity inversion is an iterative least-squares technique to obtain parameters of anomalous mass from gravity measurements. In this paper, the iterative least-squares inversion method is used to determine shapes and density contrasts of 2-D structures from the gravity data. The 2-D structures are represented by their cross-sections of N-sided polygons with density contrasts which are constant. Gravity data are calculated by theoretical formulas for the above structure models. The data are considered as observed ones and used for inversions. The inversions are performed by the following processes : 1) polygon's vertices and density contrast are initially assumed, 2) gravity are calculated for the assumed model and error between the true (observed) and calculated gravity are determined, 3) new vertices and density contrast are determined from the error by using the damped least-squares inversion method, and 4) final model is determined when the error is very small. Results of this study show that the shape and density contrast of each model are accurately determined when the density contrast is constant. Inversion of this study can be employed to improve the reliability and effectiveness of gravity interpretation and the following techniques are applied to make improvements on the stability of the inversion process : 1) alternative choice of the number of vertices. 2) carefully selecting an initial model.

비전기식뇌관의 트렁크라인 시차가 발파진동에 미치는 영향

강추원,고진석,김재웅 朝鮮大學校 建設技術硏究所 2000 建設技術硏究 Vol.20 No.1

In this study, blasting condition uniformed, and vibration value changed by the trunk line and measuring distance was measured. Four patterns of delay time of surface detonator and trunk line which are used at open fit blasting UB-25 and surface detonator of UB-17, trunk line UB-17 and surface detonator of UB-42, and trunk line of UB-25 and surface detonator of UB-42 are used in pattern 1, 2, 3, and 4 respectively, In result, the overlap time in pattern 1, 3 are 10 times respectively. Because of that reason, the value of vibration velocity in pattern 3 is smaller than in pattern 1. As the time difference of Trunk line, a method of decreasing the surface vibration is to design the number of overlap minimized a t interval time.

광양 광화대지역에 분포하는 음용지하수에 대한 지구화학적 연구

박천영,고진석,정연중,김성구 조선대학교 에너지.자원신기술연구소 2000 에너지·자원신기술연구소 논문지 Vol.22 No.2

The objective of this study is to investigate the geochemical characteristics of groundwater at Kwangyang area. Twenty two groundwater samples were collected and analyzed in vicinity of gold deposits area. The pH, Eh, EC, TDS and DO contents were measured in the field and, cation elements such as K, Na, Mg, Si, Ca, Fe, Al, Cr, Mn, Cu, Zn, As, Cd, Se. Hg, Ge and Pb were analyzed by GFAAS, AAS. ICP-MS. Anions, Cl, NO₂, NO₃and SO₄ were analyzed by IC and the HCO₃ contents were determined by titration with Phenolphthalein and. Methyl red-brom cresol green TDS vs TDI, Ca, K, Na, Mg, Zn and As contents were clearly related each other. Most groundwater showed a calcium-sulfate dominating water quality type in the Piper s diagram. On stability diagrams, the groundwaters were included in the kaolinite stable area. The increase in the Na contents correlates positively with the Cl content in the groundwater. The contents of NO₃is particularly enriched in groundwater that suggest the impact of domestic waste water results in an increase of Cl contents in the shallow groundwater.

水平層과 傾斜層 掘折媒質에서 Blind Zone 問題에 관한 硏究

金得琪,高進碩 朝鮮大學校 動力資源硏究所 1981 動力資源硏究所誌 Vol.3 No.1

The blind zone problem in three-layered sections in which the velocities of the individual layers increase with depth of their layers are solved based on the time-term equations. Blind zones are spaces which exist at every recorded refractor. In the blind zones, the traval times cannot be recorded as first arrivals. Therefore, if a blind zone is not taken into consideration, large errors in calculated refraction depths may occur. The results of the blind zone solution are as follows : 1. A blind zone may be evaluated by defining an intercept time for a blind zone velocity. 2. Blind zone depth may be evaluated by using standard time-term equations for layer thickness and depths.

광주 풍암 매립장에서의 전기탐사

이준선,서동우,고진석 조선대학교 에너지.자원신기술연구소 2000 에너지·자원신기술연구소 논문지 Vol.22 No.1

Schlumberger soundings and dipole-dipole electrical surveys were carried out in and around the Pungam landfill in June and November, 1999. To elucidate the annual variation of resistivity structure in and around the landfill, 12 electrical soundings and 6 lines of dipole-dipole surveys were conducted. Interpretations of these data show that mean resistivity values become lower and thickness of contaminated layers by leachate thicker than those of the around the landfill. Especially, mean thicknesses of saturated layers with leachate increased by about 13.6m~46.2m and resistivities of bedrock decreased. From these results, resistivity variations in the landfill indicates contamination of layers is in progress. And it appears that contamination of weathered zone is in progress mainly inside and in the front area of the landfill.