• 건축역사연구
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• 제21권4호
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• pp.71-79
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• 2012

The purpose of this research is to analyse the changes of ground level of Sungnyemun, the South Gate of Seoul City, and the principles of arch scale through the investigation based on the old records in Joseon dynasty. The result of this research is as follows: 1) The ground level of Sungnyemun, refers the level of foundation stone which was confirmed as original which is verified through the excavation conducted in 2005, maintained 1m's elevated level in 15~16 century and its elevated date presumed in King Sejong's reign(1418~1450). 2) The ground level of Sungnyemun is closely related with the royal funeral ceremony. 3) The width and height scale of Sungnyemun arch is about the ratio of 1 to 1. 4) During the Joseeon dynasty, Sungnyemun was referred as standard of other city wall gate. And it has similar architectural characteristics with Heunginjimun (or East Gate) of Seoul and Hwaseong Janganmun.

• 터널과지하공간
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• 제4권2호
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• pp.170-185
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• 1994

Surface subsidence is one of the problems caused by mined out caverns. Depending on the geologic conditions and mining methods, subsidence can occur in various forms. This report describes the ground stability assessment for the mining induced subsidence area where unfilled caverns still exist abandoned. Geologic features which could affect the stability of the ground were investigated and all the possible geophysical methods were employed to obtain data that could explain the state of the ground in question. Basic rock tests were conducted from the drill cores and rock mass classification was performed by core logging and borehole camera investigation. Numerical analyses were carried out to predict the ground stability using data obtained by various investigations. The result could have been more reliable if in-situ stress were measure and reflected in the numerical analysis.

• Geomechanics and Engineering
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• 제37권5호
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• pp.467-474
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• 2024

Monitoring and managing the condition of underground utilities is crucial for ground stability. This study aims to determine whether images obtained using ground penetrating radar (GPR) accurately reflect the characteristics of buried pipelines through image analysis. The investigation focuses on pipelines made from different materials, namely concrete and steel, with concrete pipes tested under various diameters to assess detectability under differing conditions. A total of 400 images are acquired at locations with pipelines, and for comparison, an additional 100 data points are collected from areas without pipelines. The study employs GPR at frequencies of 200 MHz and 600 MHz, and image analysis is performed using machine learning-based convolutional neural network (CNN) techniques. The analysis results demonstrate high classification reliability based on the training data, especially in distinguishing between pipes of the same material but of different diameters. The findings suggest that the integration of GPR and CNN algorithms can offer satisfactory performance in exploring the ground's interior characteristics.

• 대한원격탐사학회지
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• 제39권5_2호
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• pp.849-858
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• 2023

지진, 산사태와 같은 재난사고현장에서 조사업무는 시설물 붕괴 등 2차 재난 피해가 발생할 수 있어 많은 위험이 따른다. 이처럼 조사자가 직접 접근하기 힘든 재난현장에서 라이다(light detection and ranging, LiDAR)가 탑재된 드론 측량시스템을 통해 고정밀의 3차원 재난정보를 안전하게 취득할 수 있는 방법을 강구할 수 있다. 이에 본 연구에서는 2023년 4월 성남시 분당구의 정자교 붕괴사고 현장을 대상으로 드론 LiDAR의 재난 현장에서의 활용 가능성을 확인하였다. 이를 위해 사고 교량에 대한 고밀도 포인트 클라우드를 수집하고, 사고 교량을 3차원 지형정보로 복원하여 10점의 지상기준점 측량 성과와 비교하였다. 그 결과, 수평방향으로의 root mean square error (RMSE)는 0.032 m, 수직방향으로 0.055 m로 확인되었다. 또한, 지상 LiDAR를 통해 같은 대상지를 측량하여 생성한 포인트 클라우드와 비교한 결과, 수직방향으로 약 0.08 m가량의 오차가 발생하였지만 전체적인 형상은 큰 차이가 없을 뿐만 아니라 전체적인 데이터 취득과 자료 처리 시간 측면에서 드론 LiDAR가 지상 LiDAR보다 효율적임을 확인할 수 있었다. 따라서 많은 위험이 따르는 재난현장에서 드론 LiDAR의 활용을 통해 안전하고 신속한 현장 조사가 가능할 것으로 판단된다.

• 한국안전학회지
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• 제23권6호
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• pp.131-137
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• 2008

SCP(Sand Compaction Pile) method that forms a composite ground by driving compacted sand piles into the soft ground. This method is one of the soil improvement techniques for reinforcing and strengthening soft ground deposits. This thesis describes the investigation on the behavior of soft ground reinforced with SCP by low improvement ratio. Direct shear test and consolidation test carried out to verified behavior of composite ground reinforced with SCP. Test results were discussed with reference to the amount of consolidation settlement, variation of shear resistance with area replacement ratio and effect of the stress concentration. And, laboratory model loading test carried out to verified the effect of the location and failure mode of reinforced embankment. Residual shear strength varies with the area replacement and constrict load in the low replacement ratio. Calculated stress concentration ratio overestimate than proposed valve by experimental, theoretical and analytical method. As regards the location, improving right below of the top of the slope was more effective than below of the toe of the slope. This thesis carried out to obtain fundamental information of behavior of the composit ground. Hereafter, centrifuge test that reproduce stress state of the in-situ must be necessary through the further study about pile penetration, reinforce position and construct time.

• Geomechanics and Engineering
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• 제32권2호
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• pp.179-191
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• 2023

To study the influences of tunneling on the earth pressure and ground settlement when the tunnel passes through the adjacent underground retaining structure, 30 two-dimensional model tests were carried out taking into account the ratios of tunnel excavation depth (H) to lateral width (w), excavation width (B), and excavation distance using a custom-made test device and an analogical soil. Tunnel crossing adjacent existing retaining structure (TCE) and tunnel crossing adjacent newly-built retaining structure (TCN) were simulated and the earth pressure variations and ground settlement distribution during excavation were analyzed. For TCE condition, the earth pressure increments, maximum ground settlement and the curvature of the ground settlement curve are negatively related to H/B, but positively related to H/s and H/w. For TCN condition, most trends are consistent with TCE except that the earth pressure increments and the curvature of ground settlement curve are negatively related to H/w. The maximum ground settlement is larger than that observed in tunnel crossing the existing underground structure. This study provides an assessment basis for the design and construction under confined space conditions.

• 농업과학연구
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• 제50권3호
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• pp.507-512
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• 2023

The traditional oviposition ground for indoor breeding of Luciola lateralis is moss. This study was conducted to find the most suitable alternative oviposition ground that can maintain or increase the oviposition rate of L. lateralis while addressing the problems of larva collection time and larva loss that occur when moss is used. As alternative candidate oviposition ground comprising six colors of non-woven fabric and felt were used to measure the fecundity variation rate of L. lateralis with respect to the color and material of the oviposition ground. In addition, measure the fecundity variation rate of L. lateralis in moss, a traditional oviposition ground, was also measured and investigated for comparison. The investigation showed that the average number of eggs in the non-woven fabric group was higher than that in the felt group. The yellow non-woven fabric had an average number of eggs that was more than 100 times higher than of moss used as a traditional oviposition ground. In the space where the six color non-woven fabric were together, L. lateralis concentrated its oviposition on yellow. These results showed that yellow non-woven fabric can be sufficiently used for efficient indoor mass breeding of L. lateralis while addressing problems caused by moss, a traditional oviposition ground.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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• pp.440-445
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• 2007

This paper deals with assessment of risk component for electrical safety and investigation on the spot of computer room in elementary middle high school. The investigation was carried out side by side for floor, outlet, panel board, earth leakage circuit breaker at computer room In order to assess electrical safety at computer room, grounding simulator and power quality monitor have been used. Potential rise has been measured and analyzed for ground rod and grounding grid by using the simulator. Phase and neutral-line current have been monitored in real time. As a consequence, it is desirable for us to install conductive tile at floor of computer room Grounding grid had better than ground rod for electrical safety. Neutral-line current was produced by unbalanced phase current.

• Geomechanics and Engineering
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• 제15권3호
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• pp.911-917
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• 2018

This paper concerns a numerical investigation on the effect of construction sequence on three-arch (3-Arch) tunnel behavior. A three-arch tunnel section adopted in a railway tunnel construction site was considered in this study. A calibrated 3D finite element model was used to conduct a parametric study on a variety of construction scenarios. The results of analyses were examined in terms of tunnel and ground surface settlements, shotcrete lining stresses, loads and stresses developed in center column in relation to the tunnel construction sequence. In particular, the effect of the side tunnel construction sequence on the structural performance of the center structure was fully examined. The results indicated that the load, thus stress, in the center structure can be smaller when excavating two side tunnels from opposite direction than excavating in the same direction. Also revealed was that no face lagging distance between the two side tunnels impose less ground load to the center structure. Fundamental governing mechanism of three-arch tunnel behavior is also discussed based on the results.

• 지질공학
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• 제8권1호
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• pp.25-34
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• 1998

흙은 실제 비균질,비등방성이기 때문에 정확한 지반 특성을 파악하기는 쉽지 않다. 또한, 지반조사는 시간적, 경제적 측면에서 비효율적인 경우가 많다. 따라서, 본 연구는 지반조사의 효율적인 방법을 제시하기 위해 콘 관입치와 탄성속도에 대한 연약지반의 특성 파악에 적합한 장비로서 본 연구에서는 휴대용 원추형 콘관입시험기를 사용하였다. 휴대용 원추형 콘관입시험기는 조작이 편리하고 신속하게 지반상태를 파악할 수 있는 장점이 있다. 또한, 탄성탐사는 물리 탐사방법중 개략적 지반상태의 추정에 가장 많이 이용되는 방법으로 연약지반에 대한 이용이 계속 증가하고 있다. 콘저항치는 심도별 지층구성에 따라 일정한 군을 형성하였고 탄성파속도 또한 지층경계에 따라 일치하는 경향이 나타났다. 따라서, 타성파 속도와 콘관입저항치는 상당한 연관성을 가지고 있으며 이는 지반조사의 효율성을 증대 시킬 수 있을 것이다.