• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.4
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• pp.11-17
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• 2010

본 논문의 주된 목적은 농업용 이동로 또는 농업용수의 공급을 위하여 사용되는 파형 강판 파이프아치 암거가 고속도로 및 지방국도를 통과할 때 설계 및 시공 시 요구되는 최소 토피 두께를 제안하는데 있다. 1998년 이후 농업용 목적으로 사용되는 파형 강판 암거는 서해안 고속도로의 건설과 더불어 그 수요량이 증가하였으며, 이에 따른 설계 및 시공의 빈도수 또한 지속적으로 증가하고 있는 추세이다. 그러나 이를 뒷받침 할 수 있는 국내 규정은 아직 미약한 실정이다. 따라서 본 연구에서는 파형 강판 암거의 설계 및 시공 시 고려해야 할 가장 중요한 인자 중 하나인 최소 토피에 대한 연구를 수행하고 그 두께를 제안하였다. 현재 국내 및 미국에서 사용되고 있는 최소 토피 두께는 암거의 스판 길이 또는 스판 길이와 암거의 높이 비율의 관계로부터 정해지는 것으로 구조적인 특성치를 포함하고 있지 않다. 제안된 최소 토피 두께는 암거의 형상적 특성, 설계 하중, 강판의 구조적특성과 손상 등을 반영하여 파형 강판 암거의 안전성을 극대화 하였다. 제안된 토피 두께는 미국과 국내 도로공사에서 규정하고 있는 토피 두께와 비교 분석하였으며, 그 결과 국내 규정이 더욱 안전성을 고려하고 있음을 알 수 있었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.620-628
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• 2016

The homotopy algorithm provides a robust method for determining optimal control, in some cases the global minimum solution, as a continuation parameter is varied gradually to regulate the contributions of the nonlinear terms. In this paper, the Successive Backward Sweep (SBS) method, which is insensitive to initial guess, augmented with a homotopy algorithm is suggested. This approach is effective for highly nonlinear problems such as low-thrust trajectory optimization. Often, these highly nonlinear problems have multiple local minima. In this case, the SBS-homotopy method enables one to steadily seek a global minimum.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.230-233
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• 2004

현재 KT의 관로포설 공법은 관 상부 토피 1m를 확보한 상태에서 차량하중이 작용한다는 가정하에서 제정된 것이며, 토피 1m를 확보하지 못하는 구간에는 별도의 보강공법을 적용하고 있다. 그러나 현재 관로공사의 대부분을 차지하는 도로유관공사는 도로 조성이 종료되는 시점에는 토피 1m를 확보하지만, 도로조성 공사기간 중에는 별도의 보강공사 없이 토피 60cm 내외에서 공사 차량의 하중이 관로에 그대로 전달되고 있어 관로의 찌그러짐 현상이 발생하고 있다. 본 논문은 이와 같은 조건에서도 고품질의 관로를 확보하기 위하여 현행 FC관로 뿐만 아니라 지하매설관으로 사용되는 각종 재질의 관에 대한 특성을 검토하였으며 매설관 변형실험을 통하여 도로유관공사에 적합한 관로재질을 제시하였다.

• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.67-78
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• 2004

Soil-steel bridges are made of flexible corrugated steel plates buried in the well-compacted granular soil. One kind of possible collapses of these structures could be initiated by shear or tension failure in the soil cover subjected to vehicle loads. Current design codes provide the requirements for the minimum depth of the soil cover to avoid problems associated with soil cover failures. However, these requirements were developed for short span (less than 7.7 m) structures which are made of unstiffened plates of standard corrugation (150$\times$50 m). Numerical analyses were carried out to investigate the behavior of long span soil steel bridges according to thickness of the soil cover. The span of structures were up to 20 m and deep corrugated plates (381$\times$140 m) were used. The analysis showed that the minimum cover depth of 1.5 m could be sufficient to prevent the soil cover failure in the structures with a span exceeding 10 m. Additional analyses were performed to verify the reinforcement effect of the concrete relieving slab which can be a special feature to reduce the live-load effects. Analyses revealed that the bending moment of the conduit wall with a relieving slab was less than 20% of that without a relieving slab in a case of shallow soil cover conditions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.9
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• pp.879-888
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• 2012

This study aims to apply multistage homotopy perturbation method(MHPM) to space truss composed of discrete members to obtain a semi-analytical solution. For the purpose of this research, a nonlinear governing equation of the structures is formulated in consideration of geometrical nonlinearity, and homotopy equation is derived. The result of carrying out dynamic analysis on a simple model is compared to a numerical method of 4th order Runge-Kutta method(RK4), and the dynamic response by MHPM concurs with the numerical result. Besides, the displacement response and attractor in the phase space is able to delineate dynamic snapping properties under step excitations and the responses of damped system are reflected well the reduction effect of the displacement.

• Magazine of korean Tunnelling and Underground Space Association
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• v.17 no.3
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• pp.47-55
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• 2015

• Magazine of korean Tunnelling and Underground Space Association
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• v.25 no.3
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• pp.17-27
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• 2023

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.243-250
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• 2000

The mechanical behavior of the underground box culvert constructed by the open cut method depends mainly on the earth pressure acting on it. In this study, the earth pressure on the underground box culverts constructed by the open cut method during and after the construction sequence was numerically analysed by using FLAC. The results are compared with those of the Marston-Spangler's theory, silo theory, and the model tests. The results showed that the vertical earth pressure on the upper slab of the box structure was not uniform. It was as large as the overburden in the middle part of the slab but was smaller or larger than that at its end part depending on the slope of the excavation, the depth of the cover, and the width of the side refill. The horizontal earth pressure on the side wail was much smaller than the earth pressure at rest and grew nonlinearly with the depth.

• Tunnel and Underground Space
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• v.15 no.5 s.58
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• pp.359-368
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• 2005

In case the overburden of a tunnel is too low to adopt NATM, cut and cover method generally can be chosen as alternative. However, in tunneling some area with very low or no overburden between two mountains, the cut and cover method requires additional construction of a couple of tunnel portals and the maintenance of portal slopes until backfilling is completed. As a solution for this problem, increasing the tunnel overburden by raising the ground level can be effective. This paper presents the case study for tunneling at C240 site in Taiwan High Speed Railway(THSR) in which soil-cement filling method was used for pre-banking before tunnel excavation. Cement content of filling material was $2\~4\%$ and thickness of filling a round was $130\~250\;mm$. The stability evaluation for the soil-cement slope and concrete lining of low cover tunnel was conducted by numerical analysis.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.5
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• pp.761-778
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• 2017

The need of the underground space for the infrastructures in urban area is increasing, and especially the demand for shallow tunnels increased drastically. It is very important that the shallow tunnel in the urban area should fulfill not only its own safety conditions but also the safety condition for the adjacent structures and the surrounding sub-structure. Most of the studies on the behavior of shallow tunnels concentrated only on their behaviors due to the local deformation of the tunnel, such as tunnel crown or tunnel sidewall. However, few studies have been performed for the behavior of the shallow tunnel due to the deformation of the entire tunnel. Therefore, in this study the behavior of the surrounding ground and the stability caused by deformation of the whole tunnel were studied. For that purpose, model tests were performed for the various ground surface slopes and the cover depth of the tunnel. The model tunnel (width 300 mm, height 200 mm) could be simulationally deformed in the vertical and horizontal direction. The model ground was built by using carbon rods of three types (4 mm, 6 mm, 8 mm), in various surface slopes and cover depth of the tunnel. The subsidence of ground surface, the load on the tunnel crown and the sidewall, and the transferred load near tunnel were measured. As results, the ground surface subsided above the tunnel, and its amount decreased as the distance from the tunnel increased. The influence of a tunnel ceased in a certain distance from the tunnel. At the inclined ground surface, the wider subsidence has been occurred. The loads on the crown and the sidewall were clearly visible, but there was no effect of the surface slope at a certain depth. The load transfer on the adjacent ground was larger when the cover depth (on the horizontal surface) was lager. The higher the level (on the inclined surface), the wider and smaller it appeared. On the shallow tunnel under inclined surface, the transfer of the ambient load on the tunnel sidewall (low side) was clearly visible.