• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2183-2185
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• 2011

전기 철도시스템에는 많느 궤환 전류가 흐르고 이로 인하여 제어시스템의 오동작과 인명 손상의 위험이 따른다. 본 연구에서는 대용량의 노이즈 및 서지 전류로부터 인명과 설비를 보호를 위한 대책으로 역사간의 접지 매설 지선을 할용하여 안전성을 개선하기 위한 방안을 연구하였다. 본 논문에서는 역사내 전체의 통합접지를 구성하여 등 전위를 확보하고, 역사간 매설지선과 일정 간격 접지봉으로 시공함으로서 전기철도 선로에서 지락사고 및 낙뢰등에 대한 위험전압을 감소시킬 수 있는 방안을 시뮬레이션하여 확인하였다.

• Journal of Korean Society of Forest Science
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• v.101 no.2
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• pp.251-258
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• 2012

This study was conducted to analyze field inspection results of erosion control facilities within national forests and to suggest maintenance and management plan of erosion control facilities. The objects amounted to a total of 1,628 locations, comprising 308 erosion control dams and 1,320 erosion control areas (1,269.05 ha). The field inspections were conducted during March-June each year. The erosion control dams inspected were constructed during 1991-2005, with 96.4% of them, or 297 dams, constructed in or after 2000. The erosion control areas were constructed during 1986-2005, with 68.6% of them, or 903 areas, constructed in or after 2000. As for erosion control dams, there were 205 concrete erosion control dams and 68 concrete with boulder pitching erosion control dams, respectively, with 296 out of a total of 308 erosion control dams in a good condition. As for erosion control areas, there were many erosion control structures using stone masonry works and gabions, with 1,245 out of a total of 1,320 (94.3%) erosion control areas in a good condition. Overall, erosion control facilities within national forests were in a good condition, amply fulfilling their functions. As for erosion control facilities in a bad condition, they must be made to accomplish the goals of erosion control works through supplementation and repairs without fail. In addition, for the systematic maintenance and management of existing erosion control facilities and erosion control facilities constructed in the future as part of erosion control works, the construction of an erosion control facility management system is urgently needed.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.528-546
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• 2018

Cases of TBM tunnelling have been consistently increasing worldwide. In many recent subsea and urban tunnelling projects, TBM excavation has been preferably considered due to its advantages over drill and blast tunnelling. Difficult ground conditions are highly probable to appear in subsea and urban tunnels because of the shallow working depth and alluvial characteristics. Under the difficult ground conditions, ground reinforcement measures should be considered including grouting, while it is of great importance to select the optimal grout material and injection method to cope with the ground condition. The benefits from TBM excavation, such as fast excavation, increased safety, and reduced environmental impact, can be achieved by applying appropriate ground reinforcement with the minimum overrun of cost and time. In this report, various grouting methods were reviewed so that they can be applied in difficult ground conditions. In addition, domestic and international cases of successful ground reinforcement for difficult grounds were introduced for future reference.

• Korean Journal of Construction Engineering and Management
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• v.16 no.4
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• pp.30-40
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• 2015

Two-dimensional drawings are widely used as a communication tool in the construction industry, but they are still hard to be understood by engineers with less experience. A four dimensional CAD drawing is presented based on marker-based augmented reality, for visual assistance, detailed information, and prevention of misunderstanding among users. The developed drawing enables the users to easily understand its contents through the functions augmenting components, providing detailed construction information, and simulating construction process, using the marker in a 2D drawing. A questionnaire-based survey validates the capability of the developed drawing that it improves inexperienced engineers' understanding of the drawings.

• Journal of the Korea Concrete Institute
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• v.22 no.2
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• pp.247-254
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• 2010

The purpose of study is to investigate the load resistance mechanism of MRS continuous joint designed with different details. Six full-scale specimens, which could simulate the negative moment region of the 8 m long MRS system, were prepared to evaluate the structural performance of the continuous joint. According to the experimental results, all specimens which include the specimen with dapped ends designed by loads at the construction stage were failed in a flexural manner and showed the load carrying capacity over the nominal flexural strength. Therefore it is recommended that the dapped ends for MRS continuous joints be designed for the loads of the construction stage. And the shear key, which was installed on the top of rib for MRS slab, helps the enhancement of strength and especially deformation capacity.

• Journal of the Korean Geotechnical Society
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• v.29 no.11
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• pp.107-118
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• 2013

Geosynthetic reinforced soil (GRS) walls have been increasingly applied recently due to its numerous geotechnical engineering applications. However failure occurs in some cases of constructed GRS walls. These GRS wall failures are mostly due to the unpredictable characteristics of intensive rainfall. Hence, the need for new and innovative ideas for rehabilitation methods has been getting attention. This paper introduces a case study for the design and restoration method of collapsed GRS wall using Limit equilibrium and Numerical Analyses. Restoration method includes: (1) soil nailing without backfill excavation and (2) reconstruction with GRS wall after collapsed backfill excavation. Analyses results show minimal horizontal displacements and shear strain on the reinforced concrete facing for the restoration case with soil nailing. On the other hand, horizontal displacements are developed in the middle of the mortar block facing and shear strains are developed at the bottom facing with spiral curves for the reconstructed GRS wall after collapsed backfill excavation. Therefore, the collapsed GRS wall was restored with the soil nailing without backfill excavation and its construction procedures are discussed in this paper.

• 월간 기계설비
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• s.297
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• pp.94-103
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• 2015

삶의 터전이 부족한 자연환경을 극복하기 위해 인간은 쓸모없는 땅을 개척하고, 다리를 놓고, 둑을 막는 등 끊임없이 노력함으로써 좀더 풍요로운 삶으로 발전시켜왔다. 그 중 호수나 바닷가에 제방을 쌓고 육지를 만드는 간척은 좁은 땅덩어리를 넓힘으로써 삶의 터전을 좀더 확대시킬 수 있다. 우리나라는 삼면이 바다로 둘러싸여 있고 특히 서해안과 남해안은 리아스식 해안에 갯벌이 발달하여 간척에 유리하다. 간척은 삼국시대부터 그 흔적을 찾을 수 있고 조선시대까지는 작은 갯고랑이나 해변을 막는 정도였으나 일제 강점기 때 주로 군량미 조달 등을 목적으로 본격적인 간척이 이루어졌다. 해방 후에도 간척은 계속되었고 1980년대 이후 중장비가 등장하면서 수천 미터의 제방 길이와 거대한 물목을 틀어막는 대규모 공사로 발전하였다. 근대의 간척사업이 군량미 확보와 미곡 증산 중심이었다면 최근의 간척사업은 생태환경 복원, 관광 등 다목적 용도로 쓰임새가 변화하는 추세이다. 서해안에서는 지금 국토를 넓히는 역사적인 사업이자 최대 규모의 국책사업인 간척사업이 한창 진행 중이다. 중국 동해안을 중심으로 한국과 일본 큐슈를 잇는 환황해권이 세계 최대 경제로 떠오를 것으로 예상됨에 따라 정부가 환황해권의 주도권을 잡기 위해 새만금개발사업을 적극 추진하고 있다. 세계 최장 33km의 방조제와 $401km^2$의 땅을 매립하여 농업 산업단지, 복합도시, 21세기 동북아 관광레저의 허브 등 다용도로 활용하기 위함이다. 본지는 바닷내음 물씬 풍기는 광활한 새만금 벌판에서 새만금집단에너지시설 건설공사를 시공 중인 (주)정호이앤씨(대표 최호선) 양석동 현장소장과 원도급 업체인 두산중공업 용환윤 소장을 만났다.

• Journal of the Korean Geotechnical Society
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• v.38 no.7
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• pp.25-37
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• 2022

In this paper, a small-scale model testing system was developed using a series of small-scale model tests to analyze the mechanism of compaction pile formation and evaluate the quality of controlled grading aggregates proposed as an alternative material to the sand compaction pile (SCP) method and granular compaction pile (GCP). These are the most typical ground improvement methods in field practice, particularly for soft grounds. However, the SCP has faced difficulties due to the supply shortage of natural sand and the corresponding price surge of sand. The GCP is limited in marine soft grounds because of the failure occurring at the pile tip caused by excessive expansion of the deeper bulbs, leading to uneven bulb formation. The uniformity of compacted pile bulbs is critical to ensuring the bearing capacity and quality of the compaction pile. This study aims to evaluate the performance of the new material and controlled grading aggregates using small-scale model tests simulating field compaction process to investigate its potential application in comparison with SCP. The compaction piles are examined in four cases according to different materials used for compaction pile and clay strength. The compaction pile materials, which are made of sand and controlled grading aggregates, used in this study were compared to reveal the mechanism of the bulb creation. The experimental data confirm that the bulb formation quality of the traditional sand and the new material, controlled grading aggregates are comparable. The compaction pile made of controlled grading aggregates presents higher bearing capacity than that of marine sand.

• Tunnel and Underground Space
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• v.29 no.6
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• pp.394-406
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• 2019

Difficult ground conditions (e.g., fault zone and mixed grounds) are highly probable to appear in subsea and urban tunnels because of the shallow working depth and alluvial characteristics. TBM usually experienced decrease of penetration rate and increase of downtime when it meets these difficult ground conditions. The problems are usually caused by the adverse geological conditions, and it is preferable to determine the optimal operational parameters of TBM based on the previous operational data obtained while excavating a preceding tunnel. This study carried out for efficient TBM excavation in fault zone and mixed grounds. TBM excavation data from the tunnel site in Singapore and the characteristics of the TBM excavation data was analyzed. The key operational parameters (i.e., thrust, torque, and RPM), penetration rate, and downtime were highly influenced by the presence of fault zones and mixed grounds, and the features was discussed. It is expected that the results and main discussions will be useful information for future tunneling projects in similar geological conditions.

• Journal of the Korean Society of Hazard Mitigation
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• v.2 no.4 s.7
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• pp.131-141
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• 2002

Precast concrete (PC) panels are often used as retaining walls to support soil pressure. In such a case, the panels should be connected at the location where PC panels meet with a buttress. However, it is not easy to provide enough development length for the reinforcing steels due to the limited width of the buttress. If it happens, the width of buttress should be increased as large enough although it is not desirable. The critical section required for providing the development length is always located where the flexural moment is maximum. Thus it is the place the buttress width ends. Also it is the place that the reinforcing steels stressed to maximum. However, it is possible to make differentiate between the maximum moment location and the most stressed location of reinforcing steels. It means that the most stressed location of reinforcing steels, the critical section, can be moved to the other place where the moment is not maximum. New critical location will have less moment than that of buttress width ends. In consequence, the development length would be longer than that of the typical way of construction. Debonding or cutting technique make it possible to reduce the moment strength of a section. Therefore reinforcing steels are debonded or cut to have a desired flexural strength at a desired place. In this study, five test specimens in full scale were erected to examine the effects of critical section movement in PC panel joints. Test parameters were the length variations of debonded and cut reinforcing steels. The test results showed that the debonding or cutting technique could be used to lengthen the development length in the joint of PC panels.