• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2002년도 가을 학술발표회 논문집
• /
• pp.147-179
• /
• 2002

The important role of observational method in geotechnical engineering are emphasized together with the direction of future development, concerning successful application of the technique on the site investigation, design and feed back at various construction stages. Case histories on the application of feed back are introduced in order to achieve the most economical and reliable construction for tunnel, rock slope and deep excavations through feed back system at design and construction stages. Also the limitations and advantages of the observational method and the role of feed back system are discussed for construction of tunnel, rock slope and deep excavation in hard ground such as layered ground conditions including weathered, soft and hard rocks.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.135-136
• /
• 2006

In this paper, isolation strategies for improving broadband circuit performance and preventing noise arising from circuit component coupling are presented. Equivalent circuit parameters, including parasitic elements, are determined for capacitor and inductor structures. The effects of the relative position of the components with regard to a ground plane are considered in the equivalent circuits. Novel meshed ground structures are investigated to determine a configuration that improves the overall circuit performance.

• Structural Engineering and Mechanics
• /
• 제23권2호
• /
• pp.177-193
• /
• 2006

Determining the hysteretic energy demand and dissipation capacity and level of damage of the structure to a predefined earthquake ground motion is a highly non-linear problem and is one of the questions involved in predicting the structure's response for low-performance levels (life safe, near collapse, collapse) in performance-based earthquake resistant design. Neural Network (NN) analysis offers an alternative approach for investigation of non-linear relationships in engineering problems. The results of NN yield a more realistic and accurate prediction. A NN model can help the engineer to predict the seismic performance of the structure and to design the structural elements, even when there is not adequate information at the early stages of the design process. The principal aim of this study is to develop and test multi-layered feedforward NNs trained with the back-propagation algorithm to model the non-linear relationship between the structural and ground motion parameters and the hysteretic energy demand in steel moment resisting frames. The approach adapted in this study was shown to be capable of providing accurate estimates of hysteretic energy demand by using the six design parameters.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
• /
• pp.83-90
• /
• 1999

This paper presents a method of seismic analysis for a cylindrical liquid storage structure on horizontally layered half-space considering the effects of the interior fluid and exterior soil medium in the frequency domain. the horizontal and rocking motions of the structures are included in this study. The fluid motion is expressed in terms of analytical velocity potential function which can be obtained by solving the boundary value problem including the sloshing behavior of the fluid as well as deformed configuration of the structure. The effect of the fluid is included in the equation of motion as the impulsive added mass and a frequency-dependent convective added mass along the nodes on the wetted boundary with structure. The soil medium is presented using the 3-D axisymmetric finite elements and dynamic infinite elements. The present method can be applied to the structures embedded in ground as well as on ground since it models the soil medium directly as well as the structure. For the purpose of vertification dynamci characteristics of a tank on homogeneous half-space is analyzed. Comparison of the present results with those by others shows good agreement.

• Structural Engineering and Mechanics
• /
• 제76권2호
• /
• pp.223-237
• /
• 2020

Transmission towers have come to represent one of the most important infrastructures in today's society, which may suffer severe earthquakes during their service lives. However, in the conventional seismic analyses of transmission towers, the towers are normally assumed to be fixed on the ground without considering the effect of soil-structure interaction (SSI) on the pile-supported transmission tower. This assumption may lead to inaccurate seismic performance estimations of transmission towers. In the present study, the seismic response and failure analyses of pile-supported transmission towers considering SSI are comprehensively performed based on the finite element method. Specifically, two detailed finite element (FE) models of the employed pile-supported transmission tower with and without consideration of SSI effects are established in ABAQUS analysis platform, in which SSI is simulated by the classical p-y approach. A simulation method is developed to stochastically synthesize the earthquake ground motions at different soil depths (i.e. depth-varying ground motions, DVGMs). The impacts of SSI on the dynamic characteristic, seismic response and failure modes are investigated and discussed by using the generated FE models and ground motions. Numerical results show that the vibration mode shapes of the pile-supported transmission towers with and without SSI are basically same; however, SSI can significantly affect the dynamic characteristic by altering the vibration frequencies of different modes. Neglecting the SSI and the variability of earthquake motions at different depths may cause an underestimate and overestimate on the seismic responses, respectively. Moreover, the seismic failure mode of pile-supported transmission towers is also significantly impacted by the SSI and DVGMs.

• 복식
• /
• 제59권6호
• /
• pp.29-40
• /
• 2009

On April 28th of 2006, a set of Buddha's reliquary was excavated from the pagoda in n Nacsan Temple. According to the record, the relics were put in the pagoda in the 18th year of King SookJong in the Chosun Dynasty (1692). The present paper examines ten pieces of wrapping clothes covering reliquary found in the pagoda. They are especially precious data in the history of textiles because they were blocked off from outside and was preserved in good condition with vivid colors still remaining after more than 300 years. Of the ten pieces of wrapping cloth, five were double-layered and the other five were single-layered. They include 15 pieces of silk fabric but, excluding repeated use of the same silk fabric, the total of 11 pieces of silk fabric were examined. All 11 kinds of silk fabric were patterned, 9 of which were Satin and the other 2 were Twill. Of the 9 Satin pieces, 8 pieces were 5-end satin which had the ground of 5-end warp satin with the figure of 5-end weft satin. The remaining 1 Satin piece were more splendid with prominent figures by using warp and weft of different colors. The 2 Twill pieces used twill weave-the ground was 3-end warp twill and the figures were 5-end weft twill. Both of the Twill pieces were weaved with character patterns, partly using wrapped gold thread as supplementary weft. The patterns of 11 pieces of silk fabric include flower, dragon/phoenix, cloud, and geometric patterns. Five were flower patterns, three were dragon/phoenix patterns, two were geometric pattern, and one was cloud pattern. In addition, various treasure patterns, character patterns were utilized as supplementary patterns. The flower and phoenix patterns reflect characteristics of the textiles of the 17th century whereas check pattern and cloud pattern were very unique.

• 한국지반공학회논문집
• /
• 제19권3호
• /
• pp.5-13
• /
• 2003

쏘일네일링 공법은 작업공간의 확보가 용이하고 네일길이가 어스앵커보다 비교적 짧아 도심지 지하굴착에 매우 이로운 장점이 있다. 이 공법이 도입된 이후 쏘일네일링 벽체의 거동에 관한 연구는 토조에 의한 모형실험과 이론적 연구가 진행되고 있지만 지반조건이 다층토로 구성된 현장에 대한 연구는 미흡한 실정이다. 본 연구는 국내 다층토 지반에 시공된 쏘일네일링 현장에서 시공중 측정된 수평변위를 토대로 한 역해석적 방법에 의해 배면지반의 이완영역거리와 이완영역계수를 고찰하였다. 연구결과에 의하면 쏘일네일링 벽체 배면지반의 이완 영역거리는 최종굴착깊이의 증가에 따라 증가함을 보였으며, 그 비율은 최종굴착깊이의 94% 정도로 나타났다. 토사층과 암층이 혼합되어 있는 다층토 지반에서 토사층의 비율이 클수록 이완영역계수도 증가하였으나, 약 1.05값에서 수렴하는 경향을 나타냈다. 벽체 최대수평변위에 대한 지표면 최대수직변위와의 관계는 역해석결과에서 지표면 최대수직변위가 최대수평변위의 80%이하로 나타났으며, Caspe방법에 의한 지표면 최대수직변위는 최대수평변위의 150~280%의 범위로 나타나 역해석결과보다는 매우 큰 값을 나타내 Caspe방법이 매우 보수적임을 확인하였다.

• Geomechanics and Engineering
• /
• 제36권2호
• /
• pp.167-181
• /
• 2024

The soil-structure relative stiffness is a key factor affecting the seismic response of underground structures. It is of great significance to study the soil-structure relative stiffness for the soil-structure interaction and the seismic disaster reduction of subway stations. In this paper, the dynamic shear modulus ratio and damping ratio of an inhomogeneous soft soil site under different buried depths which were obtained by a one-dimensional equivalent linearization site response analysis were used as the input parameters in a 2D finite element model. A visco-elasto-plastic constitutive model based on the Mohr-Coulomb shear failure criterion combined with stiffness degradation was used to describe the plastic behavior of soil. The damage plasticity model was used to simulate the plastic behavior of concrete. The horizontal and vertical relative stiffness ratios of soil and structure were defined to study the influence of relative stiffness on the seismic response of subway stations in inhomogeneous soft soil. It is found that the compression damage to the middle columns of a subway station with a higher relative stiffness ratio is more serious while the tensile damage is slighter under the same earthquake motion. The relative stiffness has a significant influence on ground surface deformation, ground acceleration, and station structure deformation. However, the effect of the relative stiffness on the deformation of the bottom slab of the subway station is small. The research results can provide a reference for seismic fortification of subway stations in the soft soil area.

• ETRI Journal
• /
• 제40권4호
• /
• pp.546-553
• /
• 2018

Since the Gyeongju earthquakes in 2016, there have been increased research interests in the areas of seismic design, building collapse, and rescue radar applications in Korea. Ground penetrating radar (GPR) is a nondestructive electromagnetic method that is used for underground surveys. To properly design ground penetrating radar that detects buried victims precisely, it is important to study electromagnetic wave propagation channel characteristics in advance. This work presents an electromagnetic propagation environment analysis of a trapped victim for GPR applications. In this study, we develop a realistic collapse model composed of layered reinforced concrete and a victim positioned horizontally. In addition, the effects of rebars and the distance between the radar antenna and target are investigated. The numerical analysis presents the electromagnetic wave propagation characteristics, including amplitude loss and phase difference, in the 450-MHz and 1,500-MHz frequency band, and it shows the electric field distribution in the environment.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2007년 가을학술발표회
• /
• pp.78-89
• /
• 2007

Two design examples of deep foundations for high-rise buildings on soft ground are introduced in this paper. The first one is a 54-story building in Ho-Chi-Minh city, Vietnam, which was designed to be founded on $2.8m{\times}1.0m$ barrette foundations with approximately 60m to 75m depth. Based on a number of design guides and existing load test data from the construction sites in Ho-Chi-Minh city, the capacity of a barrette foundation in sand or clay layered ground was calculated to be 17.2MN to 27.8MN depending on the installing depth. The second one is a 40-story building in Baku city, Azerbaijan, which was designed to be supported by 2.0m diameter bored pile foundations with approximately 23m depth. As analytical or empirical guides for the local ground conditions were very limited, the design procedure from the SNiP Code, one of Russian specifications, was adopted and used to calculate the pile capacity. The capacity of bored pile foundation in highly weathered soil was expected to be 14.8MN to 15.5MN depending on the boring depth.