• Land and Housing Review
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• v.7 no.4
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• pp.261-269
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• 2016

Pipe-roof method is one of the mostly used method to prevent the ground subsidence during the tunnel construction. As pipe-roof method has made technical advancement and performance improvement, it suggested to utilize pipe-roof to a permanent support system rather than a temporal pre-reinforcing method. Therefore, in this study, pipe-roof method is numerically simulated using finite element method to evaluate effects of pipe-roof on behavior of ground and structure. Analyses are performed considering two major conditions that are with and without the application of pipe-roof and the shape of tunnel cross section. The results are presented with respect to variation of settlement and vertical stress distribution. Based on this results, it is found that ground settlement above the shallow tunnel can be considerably reduced by application of pipe-roof system. Also, the shape of tunnel cross section can influence on the mechanical behavior of ground and structure.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.377-387
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• 2016

In recent, in case that the underpass is constructed by trenchless method, its stability increases by reinforcing steel pipe with re-bar and mortar after propulsion into the ground to form pipe-roof. Therefore, it can be predicted that the integrated pipe-roof decreases the stress acting on the underpass by sharing load. In this study, to analyze the effect of integrated pipe-roof and behavior of stress around underpass, experimental tests for the rectangular and arch cross section of the underpass are performed using soil chamber. As a result, stress and strain acting on the underpass decrease due to sharing load by integrated pipe-roof. This phenomenon is more pronounced by increasing the stiffness of pipe-roof. Furthermore it can be expected that cross-section of underpass can be economically designed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.5
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• pp.455-468
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• 2013

In recent, various types of steel pipe-roof methods, which is reinforced by mortar after propulsion of steel pipe into the ground, have been used for the construction of trenchless underpass. Integrated steel pipe-roof has flexural stiffness and can resist against overburden load and reduce the stress acting on the concrete underpass structures. Due to arching effect, vertical and horizontal stress distribution around the steel pipe-roof is changing. In this study, therefore, the characteristic of stress distribution around the underpass induced by the construction of integrated steel pipe-roof is investigated by using numerical method. To examine the soil-structure interaction, interface element is introduced. Results show that vertical stress acting on the concrete structure placing inside the steel pipe-roof is significantly reduced due to arching effect and flexural stiffness of integrated steel pipe-roof. Design load can be reduced and effective design of underpass will be available if the earth pressure reduction due to arching effect is considered in the design stage.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.30.2-30.2
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• 2005

• The Transactions of the Korea Information Processing Society
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• v.5 no.5
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• pp.1172-1184
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• 1998

ILP(Instruction Level Parallelism) processors use code reordering algorithms to expose parallelism in a given sequential program. When applied to a loop, this algorithm produces a software-pipelined loop. In a software-pipelined loop, each iteration contains a sequence of parallel instructions that are composed of data-independent instructions collected across from several iterations. For vector loops, however the software pipelining technique can not expose the maximum parallelism because it schedules the program based only on data-dependencies. This paper proposes to schedule differently for vector loops. We develop an algorithm to detect vector loops at object code level and suggest a new vector scheduling algorithm for them. Our vector scheduling improves the performance because it can schedule not only based on data-dependencies but on loop structure or iteration conditions at the object code level. We compare the resulting schedules with those by software-pipelining techniques in the aspect of performance.

• Geotechnical Engineering
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• v.34 no.1
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• pp.57-71
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• 2018

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1585-1592
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• 2008

산업사회의 발전에 따라 사회 기반시설분야도 복잡다양해지고 특히 도시기능이 활발해지면서 지금의 도심지에는 지하철, 상수도, 하수도, 전력구, 통신구, 지하보차도, 지하상가, 지하주차장 등 여러 가지 용도의 지하공간이 요구되고 있으며, 이러한 지하 구조물을 축조하는데 있어 도로상에 차량 증가로 인한 교통 혼잡이나, 지하매설물의 장애로 인하여 기존의 개착식 공법으로 시행하지 못하고 지하터널공사로 시행하는 경우가 빈번하다. 기존 국내 외 터널공법 관련문헌과 현재 사용되는 터널공법의 실제 시공에 관한 정보를 수집하여 장 단점, 시공시 주의사항, 적용조건등의 조사내용을 바탕으로 RPS 공법을 고안하였다. 소규모 지하구조물을 구축하기 위한 RPS 공법은 출발갱내에서 상부에 파이프 루프를 시공한 후 광폭 유압 패널이 장착된 철제 선도관을 추진시켜 선도관을 원압잭에 의하여 압입한 후 P.C. 콘크리트 구조물을 거치하고 원압으로 압입 추진토록 하였다. 또한, 대규모 지하구조물 축조시에는 구조물 예정상단부에 지반조건에 따라 파이프 루프공법 또는 소구경 Semi-Shield 공법을 이용하여 루프를 시공함으로써 상부의 침하를 방지하고, 측벽은 광폭유압 패널을 이용하여 여굴의 최소화 및 곡선부 시공을 용이하게 하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.5
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• pp.513-522
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• 2015

This study is to confirm the effect of pre-installed pipe-roof by measuring earth pressure acting on the underpass. In recently developed trenchless methods pre-inserted steel pipes before ground excavation to form pipe-roof are connected each other with re-bars and filled with mortar. In this study, focusing on the Upgraded Pipe Roof Structure method (UPRS) and Front-Jacking, earth pressure around pipe-roof is measured after insertion of steel pipe to ensure the effect of earth pressure reduction. In case of the UPRS earth pressure is considerably reduced because of the reinforced effect of pipe-roof. In case of the Front-Jacking in which the whole underpass structure is pushed into the ground, earth pressure is not reduced as expected, because the pre-installed pipes are not needed to be reinforced.

• Journal of the Korean Geosynthetics Society
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• v.12 no.4
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• pp.143-147
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• 2013

Geothermal energy is easy to take advantage of renewable energy stored in the earth and the heat exchanger can be collected through a heat exchange piping system. In this study, have been developed a heat exchange pipe loop system which it could be installed in tunnel segmental linings to collect geothermal energy around the tunnel. The heat exchange pipe loop system incorporated in the tunnel segments circulate fluid to transport with heat from the surrounding ground and the heat can be used for heating and cooling of nearby structures or districts. The segmental lining incorporating heat exchange pipe loop system are called as ELS (Energy Lining Segment). There are a number of examples incorporating a heat exchange pipe loop system in a tunnel lining in Europe. In this study, a field case using Energy Lining Segment in Germany and applications in urban area are thoroughly examined. In addition, a CFD (Computational Fluid Dynamics) analysis was carried out to investigate heat flow in Energy Lining Segment.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.6
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• pp.717-726
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• 2002

In this study, we analyze hardware implementation schemes of the ARS(Advanced Encryption Standard-128) algorithm that has recently been selected as the standard cypher algorithm by NIST(National Institute of Standards and Technology) . The implementation schemes include the basic architecture, loop unrolling, inner-round pipelining, outer-round pipelining and resource sharing of the S-box. We used MaxPlus2 9.64 for VHDL design and simulations and FLEX10KE-family FPGAs produced by Altera Corp. for implementations. According to the results, the four-stage inner-round pipelining scheme shows the best performance vs. cost ratio, whereas the loop unrolling scheme shows the worst.