• Geophysics and Geophysical Exploration
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• v.25 no.1
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• pp.44-49
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• 2022

Closed-form expressions of vector gravity and gravity gradient tensor based on a line segment are derived. If a cylindrical object with axial symmetry is observed from a distance, it is possible to approximate it as a line segment; therefore, it is necessary to compute the gravity and the gravity gradient tensor due to a line source by using closed-form expressions. The gravitational potential for a line segment is defined as a one-dimensional integral, and this integral is differentiated with respect to the Cartesian coordinate system to derive the vector gravity. The expressions of the gravity gradient tensor are derived by differentiating the vector gravity once more in the same coordinate system.

• Geophysics and Geophysical Exploration
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• v.9 no.2
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• pp.171-175
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• 2006

Gravity reduction and Bouguer anomaly are frequently misunderstood by many geoscientists as follows; the observed gravity is reduced to a common datum plane, so that gravity effects by all materials above the datum is removed, therefore, Bouguer anomaly is located on the datum plane. In reality, Bouguer anomaly does not lie on a common datum plane, but is difference between observed gravity and reference gravity at the actual point of measurement. Commonly used gravity reduction formulas are approximate formulas. Here, we introduce complete formulas, and suggest to use them for more accurate results. We also suggest to use not the geoid but the reference ellipsoid as the vertical datum.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1991.07a
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• pp.98-98
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• 1991

항만 및 연안역 이용이 다변화되고 방파제를 설치할 지점의 수심이 깊어짐에 따라 기존의 착저 중력식 방파제는 한계점을 노출하고 있으며, 각 이용목적에 보다 부합되는 형태의 신소파제 개발이 요구되고 있다. 기존의 착저 중력식 방파제는 외해로부터의 파랑을 차단하는 데에는 탁월한 성능을 가지나 항내의 해수순환을 차단하여 수질악화 등의 환경문제를 유발시키는 문제점이 있으며, 대수심에 설치해야 할 경우에는 공사비가 많이 들며 시공이 어려워진다.(중략)

• Geophysics and Geophysical Exploration
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• v.23 no.1
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• pp.55-60
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• 2020

The closed-form expressions of gravity, magnetic, gravity gradient tensor, and magnetic gradient tensor due to a rectangular prism are derived. The vertical gravity is derived via triple integration of a rectangular prism in Cartesian coordinates, and the two horizontal components of vector gravity are then derived via cycle permutation of the axis variables of vertical gravity through the axial symmetry of the rectangular prism. The gravity gradient tensor is obtained by differentiating the vector gravity with respect to each coordinate. Using Poisson's relation, a vector magnetic field with constant magnetic direction can be obtained from the gravity gradient tensor. Finally, the magnetic gradient tensor is derived by differentiating the vector magnetic with respect to appropriate coordinates.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.307-311
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• 2006

일반적으로 도달시간은 지표면 유출의 흐름상태에 의존하며, 대개 중력흐름으로 가정하여 도달시간을 산정하고 있다. 본 연구에서는 흐름상태를 중력흐름과 표면장력흐름으로 구분하고 각 흐름을 판단할 수 있는 임계치를 추정하였다. 도달시간 산정을 위해 유역경사와 지표면조고의 영향을 고려할 수 있는 무차원수를 도입하였으며, 이 임계치의 범위에 따라 중력흐름과 표면장력흐름을 구분하고 두 조건의 흐름상태에 따른 도달시간 산정식을 각각 개발하였다. 중력흐름에 의한 도달시간 산정식과 표면장력흐름에 의한 도달시간 산정식을 개발하고 검증하기 위하여 기존 외국에서 실험한 자료를 비교 분석하였다. 분석결과를 통하여 이러한 흐름특성을 고려한 도달시간 산정식을 모형에 적용할 경우 유출모형을 통한 유출량산정의 정확도 향상에 기여할 것으로 판단된다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.4-6
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• 2022

중력식 등표는 내·외적으로 충분한 구조적 안정성을 갖도록 설계되고 있으나, 시공 시 해상공사 특성 상 불가피하게 발생하는 재료 유실은 상당한 구조적 안정성 저해 요소로 작용할 수 있다. 이에 따라, 시공 시 재료 유실을 최소화 할 수 있도록 토목섬유를 활용하는 방안을 제시하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.74-85
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• 2022

The purpose of this paper is to review the applicability of the current standards for the evaluation method of input variables and performance level in seismic performance evaluation by dynamic plastic analysis of the concrete gravity-type dam to which MCE is applied, and to suggest improvements. To this end, a domestic concrete gravity-type dam was selected as a target facility, dynamic plasticity analysis was performed under various conditions, and applicability to input variables such as concrete tensile strength and breaking energy, was reviewed. By analyzing the effect of cracks at the bottom of the gravity dam on the stability of the activity, an improvement plan for the performance level evaluation method required to secure the water storage function was derived. If the proposed improvement plan is applied, it will have the effect of deriving more reasonable evaluation results than the current seismic performance evaluation method to which MCE is applied.

• Journal of the Korean GEO-environmental Society
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• v.23 no.11
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• pp.13-18
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• 2022

In this study, the suitability of the grouting method will be evaluated by analyzing seismic reinforcement methods for the stability of gravity structure in Port. The evaluation categories are liquefaction, sliding, toppling and circular failure. To compare the appropriateness of the seismic reinforcement method, the low mobility mortar injection, one of the grouting method and the SPC file and GRB method, which are pile wall type reinforcement methods, were evaluated and compared respectively. The object of the evaluation is the gravitational structure of Po-Hang old port. As a result of the evaluation, both the grouting method and the pile wall type reinforcement method are considered to have sufficient stability. Therefore, in the case of the gravity structure, the grouting method is more efficient than the seismic reinforcement method considering construction efficiency, economic efficiency, maintenance and similar construction cases.

• Journal of Ocean Engineering and Technology
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• v.1 no.2
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• pp.52-59
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• 1987

극 지역용 중력식 해양구조물의 설계시 고려되어야 할 문제중의 하나가 구조물의 유빙(ice)과 충돌시 야기되는 foundation붕괴 현상인데, 본 논문에서는 정적 해석을 위해 sliding 및 bearing failure 현상에 대하여만 연구하였고, 또한 동적 해석을 위하여 soil과ice의 특성으로부터 structure-ice-soil의 상호 작용 운동 방정식을 설정하여 구조물과 ice의변위, 속도, 가속도와 ice force와 soil force의 history를 시간영역 해법으로 풀었다. 한 예제로 Beaufort Sea의 37 feet수심과 granular soil 상태에서 구조물의 최대변위는 0.4 feet이고 가속도는 약 0.3kg이며 이때 구조물이 sliding에 대하여 안전하다는 것이 입증되었다.

• Journal of the Korean Geotechnical Society
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• v.16 no.4
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• pp.129-139
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• 2000

The liquefaction of reclaimed land generally caused the harbor facilities to hazards. In Korea, the major harbor quay walls are gravity type and the gravity quay wall is not a good earthquake resistant structure. Recently, various earthquake resistant quay walls have been suggested, but the study on the efficiency of reinforced quay wall was not much performed. In this study, numerical analysis is carried out for performance evaluation of easily adoptable earthquake resistant quay walls. The results of numerical analysis are compared with shaking table test that is performed at the same cross-section.