• 산업기술연구
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• 제27권B호
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• pp.115-119
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• 2007

Currently, geophysical method is applied for understanding the subsurface geologic structure economically and systematically, but there exists some limitations on recognizing complex subsurface structures precisely by a single geophysical method. In order to understand the complex subsurface structures, we applied various geophysical methods including seismic refraction survey, two-dimensional resistivity survey, seismic tomography survey, suspension-ps log, and understood distribution of low velocity, low resistivity range of resistivity survey and correlation of an intersecting point, velocity distribution of seismic tomography survey.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.245-248
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• 2001

During the core drilling for the design of a railway bridge crossing over the inferred fault system along the river, fracture zone, extends vertically more than the bottom of borehole, filled with fault gouge was found. The safety of bridge could be threatened by the excessive subsidence or the reduced bearing capacity of bedrock, if a fault would be developed under or around the pier foundation. Thus, a close examination of the fault was required to rearrange pier locations away from the fault or to select a reinforcement method if necessary. Geophysical methods, seismic reflection method and electrical resistivity survey over the water covered area, were applied to delineate the weak zone associated with the fault system. The results of geophysical survey clearly showed a number of faults extending vertically more than 50m. Reinforcement was not desirable because of the high cost and the water contamination, etc. The pier locations were thus rearranged based on the results of geophysical surveys to avoid the undesirable situations, and additional core drillings on the rearranged pier locations were carried out. The bedrock conditions at the additional drilling sites turned out to be acceptable for the construction of piers.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.376-383
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• 2005

In this study, we conducted geophysical investigations for the organization of integrated geophysical methods to detect underground cavities of ground subsidence area at the field test site, located at Yongweol-ri, Muan-gun. We examined the applicability of geophysical methods such as electrical resistivity, electromagnetic, and microgravity to cavity detection with the aid of borehole survey results. Underground cavities are widely present within the limestone bedrock overlain by the alluvial deposits in the area of the test site where the ground subsidences have occurred in the past. The limestone cavities are mostly filled with groundwater and clays in the test site. Thus, cavities have low electrical resistivity and density compared to the surrounding host bedrock. The results of the study have shown that the zones of low resistivity and density correspond to the zones of the cavities identified in the boreholes at the site, and that the geophysical methods used are very effective to detect underground cavities. Furthermore, we could map the distribution of cavities more precisely with the test results incorporated from the various geophysical methods. It is also important to notice that the microgravity method is a very promising tool since it has rarely used for the cavity detection in korea. Beyond the investigation of underground cavities, the geophysical methods are required to provide useful information for the reinforcement design for the ground subsidence areas. It is, therefore, necessary to develop integrated geophysical technique incorporating different geophysical methods to precisely map underground cavities and image the subsurface of the ground subsidence areas.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.493-498
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• 2003

In case of slope failure by planted protection is constructed on the slope according to of the choice trend of a recently environmental-friendly countermeasure, there has a limitation about diagnosis and preparation of measure. Also, collapse of tunnel pithead department slope has maximum in construction and countermeasure method of construction choice unlike cut-slope. In this study, analyzed inside circumstance of slope using geophysical exploration for stability analysis and countermeasure inside presentation of tunnel pithead department slope which collapse happens. geophysical exploration used dipole(Dipole-Dipole) method that is based to distribution principle does specific resistance, goes side by side with on-the-spot observation and draws base strength parameter and executed stability analysis, and presented stabilization countermeasure inside of collapse slope on this. I wish to conduce in development and research for use technical development of geophysical exploration technique hereafter by executing geophysical exploration in road collapse spot applying through this study.

• 지질공학
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• 제27권3호
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• pp.305-312
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• 2017

The most effective way to distinguish subsurface interfaces that produce various geophysical responses is through the integration of multiple geophysical methods, with each method detecting both a complementary and unique set of distinct physical properties relating to the subsurface. In this study, shallow seismic reflection (SSR) and ground penetrating radar (GPR) surveys were conducted at the Cheongju-Gadeok site of the Korea National Groundwater Monitoring Network to map the water table, which was measured at 12 m depth during the geophysical surveys. The water table proved to be a good target reflector in both datasets, as the abrupt transition from the overlying unsaturated weathered rock to the underlying saturated weathered rock yielded large acoustic impedance and dielectric constant contrasts. The two datasets were depth converted and integrated into a single section, with the SSR and GPR surveys conducted to ensure subsurface imaging at approximately the same wavelength. The GPR data provided detailed information on the upper ~15 m of the section, whereas the SSR data imaged structures at depths of 10-45 m. The integrated section thus captured the full depth coverage of the sandy clay, water table, weathered rock, soft rock, and hard rock structures, which correlated well with local drillcore and water table observations. Incorporation of these two geophysical datasets yielded a synthetic section that resembled a simplified aquifer model, with the best-fitting seismic velocity, dielectric constant, and porosity of the saturated weathered layer being $v_{seismic}=1000m/s$, ${\varepsilon}_r=16$, and ${\phi}=0.32$, respectively.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.54-57
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• 2007

Recently, multidimensional joint inversion of geophysical data based on fundamentally different physical properties has been actively studied. Joint inversion can provide a way to much more accurately image the subsurface structure. Through the joint inversion, furthermore, it is possible to directly estimate non-geophysical material properties from geophysical measurements. In this study, I derive the objective functions and normal equations of three different joint inversion approaches: one approach based on the structural similarity using cross-gradient, and the other two using the a priori information on the model parameters and the correlation between material properties. Since all the equations derived in this study are based on the same inversion method (smoothness constrained least-squares), it is possible to mix the joint inversion methods so as to produce a new joint inversion algorithm.

• 지구물리와물리탐사
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• 제27권1호
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• pp.69-83
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• 2024

사용후핵연료 심층처분 부지조사는 그 중요성과 특수성을 고려할 때, 터널, 교량 등과 같은 일반적인 지반조사와는 달리 높은 수준의 품질관리가 요구된다. 본 논문에서는 단계별 부지조사에 적용할 물리탐사 기법을 선정하고, 탐사방법별 물리탐사 수행지침서를 작성한 사례를 소개하고자 한다. 물리탐사 수행지침서는 탐사계획, 자료획득, 자료처리 및 해석의 수행 절차와 고려사항 및 품질관리에 대한 내용이 포함되어 있으며, 이 중 항공전자탐사와 탄성파 반사법탐사 내용을 간략히 정리하였다.

• 지구물리와물리탐사
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• 제11권3호
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• pp.221-229
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• 2008

최근 자원개발 분야에서는 다양한 자료를 3차원 공간 데이터베이스로 구성하여 매장량, 품위 분포 등 경제성 평가에서부터 광산설계, 채굴계획 수립 및 가행단계의 공정관리 등 광산개발의 전주기에 대한 3차원 모델링 기법에 널리 활용하고 있다. 자원개발 분야와 토목분야에서 물리탐사는 현지 여건, 기술적, 경제적 제한 때문에 대부분 2차원 단면에 대한 탐사를 주로 하고 있다. 현장에서 획득된 탐사 자료는 2차원 가정을 전제로 한 2차원 역산을 통해 지하 매질의 물성 분포를 계산하는데 이용된다. 그러나 실제로 획득된 자료는 3차원 공간에서의 지하 매질의 반응이므로, 2차원 역산의 결과는 3차원 지형 정보와 지질구조, 시추조사 결과 등과 같은 부가적인 정보를 고려하여 종합적으로 해석함으로써 2차원 가정에 의한 오류를 최소화하고 실제 지하 매질의 특성을 파악할 수 있다. 이 연구에서는 토목 및 자원개발 분야에서 수행된 물리탐사 자료에 대하여 3차원 지반 모델링 기법을 적용한 사례 연구를 통해 3차원 지반 모델링 기법의 활용성과 다양한 적용 가능성을 검토하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.237-240
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• 2004

In this study, the digital image processing with image enhancement based on homomorphic filtering was performed using geophysical imaging data such as gravity, magnetic data and sub-scenes of satellite images such as LANDSAT, IKONOS, and KOMPSAT. Windows application program for executing homomorphic filtering was designed and newly implemented. In general, homomorphic filtering is technique that is based on Fourier transform, which enhances the contrast of image by removing the low frequencies and amplifying the high frequencies in frequency domain. We can enhance the image selectively using homomorphic filtering as compared with the existing method, which enhance the image totally. Through several experiment using remotely sensed imagery and geophysical image with this program, it is concluded that homomorphic filtering is more effective to reveal distinct characteristics for some complicated and multi-associated features on image data.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2001년도 정기총회 및 제3회 특별지포지움
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• pp.90-93
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• 2001

다양한 토양 오염 복원 기술이 개발되었고 여러 가지 제한 요인을 제거하는데 주력 해왔다. 결정 요인 중 하나인 지구물리학적 특성 중 투수계수, 전기전도도, 열전도도를 이용한 복원 공법에 대해 재고해 보았다. 복원 대상이 되는 토양내 여러 가지 특성을 이해하고 그의 분포에 대한 정확한 정보를 가지고 있을 때, 가장 효율적인 공법의 선택이 가능하다.