• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.1
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• pp.38-49
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• 1988

This paper presented as follows results of laboratory model tests with various shaped footings on soil bed reinforced with the strips on the base of behaviour of soil structure according to the loads and triaxial test results reinforced with geotextiles. Their parameters studied were the effects on the bearing capacity of a footing of the first layer of reinforcement, horizontal and vertical spacing of layers, number of layers, tensile strength of reinforcement and iclination load to the vertical 1.Depending on the strip arrangement, ultimate bearing capacity values could be more improved than urreinforced soil and the failure of soil was that the soil structure was transfered from the macrospace to microspase and its arrangement, from edge to edge to face to face. 2.The reinforcement was produced the reinforcing effects due to controlling the value of factor of one and permeable reinforcement was never a barrier of drainage condition. 3.Strength ratio was decreased as a linear shape according to increment of saturation degree of soil used even though at the lower strength ratio, the value of M-factor was rot influenced on the strength ratio but impermeable reinforcement decreased the strength of bearing capacity. 4.Ultimate bearing capacity under the plane-strain condition was appeared a little larger than triaxial or the other theoretical formulars and the circular footing more effective. 5.The maximum reinforcing effects were obtained at U I B=o.5, B / B=3 and N=3, when over that limit only acting as a anchor, and same strength of fabric appeared larger reinforcing effects compared to the thinner one. 6.As the LDR increased, more and more BCR occurred and there was appeared a block action below Z / B=O.5, but over the value, decrement of BCR was shown linear relation, and no effects above one. 7.The coefficient of the inclination was shown of minimum at the three layers of fabrics, but the value of H / B related to the ultimate load was decreased as increment of inclination degree, even though over the value of 4.5 there wasn't expected to the reinforcing effects As a consequence of the effects on load inclination, the degree of inclination of 15 per cent was decreased the bearing capacity of 70 per cent but irnproved the effects of 45 per cent through the insertion of geotextile.

• The Journal of Engineering Geology
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• v.18 no.3
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• pp.245-255
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• 2008

The variation of the electrical property of embankment material was analyzed from laboratory experiments and the result of field survey, in order to enhance the interpretation of electrical resistivity survey frequently used for safety assessment of embankment. At first, the kaolinite, showing similar physical property with core material of embankment, was used to examine the variation of the resistivity value according to degree of consolidation. The test showed that a drop of shear strength induces increase of resistivity value regardless of degree of water content. This result means that porous zones of weak core material in embankment may be appeared as highly resistive part in the electrical resistivity survey. This observation implies that it may fail to detect weak core material by electrical method, if we only try to and zones showing low resistivity value. And, we performed Standard Penetration Test (SPT) to analyze the correlation between electrical property and ground stiffness. Finally, a mechanism to describe the variation of electrical resistivity due to grouting effect was proposed and real field data were analyzed.

• Journal of Conservation Science
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• v.32 no.4
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• pp.561-570
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• 2016

This research was a technical case study for the authentic restoration of the seven-storied Simgoksa stone pagoda after disassembly and reconstruction using three-dimensional image analysis. During disassembly and reconstruction, the pagoda's properties were analyzed in terms of the overall modification and displacement of the pagoda. Distortion was minimized by ensuring structural stability during the reconstruction process. Also, the original site of the pagoda was examined in order to utilize it fully during rebuilding. Before reconstruction of the pagoda, moss and lichen on the stone surfaces were removed by scientific surface cleaning. The foundation of the pagoda was reinforced with rammed earth than was similar to the original foundation using a mixture of soil and quicklime. The results are expected to provide valuable data for the reconstruction of other stone pagodas.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.6
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• pp.118-124
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• 2009

In order to know the range of install possibles of the horizontal stay without general stay, strength characteristic tests were performed for the Vertical and 80[$^{\circ}$] inclined concrete poles. From the results of one cycle strength tests, the safety factors were 2.8, 2.5 and 2.1 for the poles of general load, heavy load and high strength load, respectively. However, the crack was occurred when the bending bounds of upper part of pole was above 2[$^{\circ}$], and working load was similar to the rated load of pole at this time. Therefore, it could be concluded that the reinforcement by the installation of the stay and the support was necessary certainly, if the bending bounds of pole, which was installed on a solid foundation, are above 2[$^{\circ}$].

• Tunnel and Underground Space
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• v.8 no.4
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• pp.321-331
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• 1998

A reliable analysis of tunnelling is needed to accomplish technically sound design and safe and economical construction. For the reliable analysis, a series of procedures of construction which include excavation and support stages must be considered. In this study, rock-support response behavior is studied and simulated in 2-D and 3-D finite element methods. Through the analysis of rock-support response behavior, the effects of the properties of shotcrete on the load distribution ratio can be quantified. The load distribution ratios for different rock types, different unsupported spans and various lateral earth pressure coefficients can be determined from the results of the 3-D finite element analysis. This load distribution ratios can be applied to a practical tunnel design through understanding of the trend of those various factors affecting the rock-support interaction.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.242-242
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• 2017

산업혁명 이후 인간사회의 산업화 및 도시화의 가속으로 지구온난화는 기후변화를 야기해 왔으며, 이로 인한 각종 부정적인 영향과 심각성은 날로 커져가고 있는 현실이다. IPCC(Intergoverment Panel on Climate Change)는 기후변화의 주범인 온실가스를 감축할 지라도 기후의 탄성 때문에 앞으로 수세기 이상 계속 진행될 것으로 전망하였으며, 기후변화 영향의 근원적 방지는 불가능하기 때문에 결국 수자원 관리 측면에서도 기후변화에 적응하기 위한 각종 적응전략 개발의 필요성을 강조하였다(IPCC, 2007). 최근 제방의 안정성에 대한 문제로 기후변화에 따른 홍수위 또는 담수 등의 조건으로 제외지의 고수위를 유지하게 되어 제체 내 침투가 일어날 수 있고, 수위급강하로 제방사면의 활동등이 일어날 수도 있으며 기초지반의 지지력이 부족하여 침하가 과다하게 발생하므로 제방의 소요높이를 유지할 수 없게 되어 월류로 인한 피해가 발생할 수 있다. 본 연구는 제방의 간극수압자료와 2차원 지하수침투 모형인 SEEP/W를 이용하여 안양천과 오산천의 침투거동을 분석하여 침투안정성을 평가하고자 하였다. 또한, 4대강 살리기 마스터 플랜(국토해양부, 2009)에 수록된 제방보강의 방법 중 누수에 대하여 제방고, 제방폭 및 제내지반고의 변화를 통한 지하수 침투거동을 모의, 분석하여 침투안정성을 평가하였다. 또한 기후변화에 따른 도시하천의 수문특성 변화분석 결과를 바탕으로 향후 발생할 수 있는 극치 수문사상의 값을 반영한 설계기준 강화 수방시설 계획 등의 연구에 활용하며, 여러 가지 수문학적 불확실성에 의하여 가변 가능한 도시하천 유역의 취약성 평가 및 위험도 분석을 통한 기후변화 대응과 수공구조물 설계 및 수방전략 수립에 활용하고자 한다.

• Journal of the Korean Geophysical Society
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• v.4 no.1
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• pp.11-20
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• 2001

Seismic refraction and electrical resistivity surveys were conducted in Bangeosan Maaebul site located in Haman, Kyungnam, in order to present geophysical safety analysis method for masonry cultural properties. Seismic refraction exploration revealed that the ground was composed of three layers in term of seismic wave velocity; the upper, medium, and lower layers. The low velocity ranging from 308 to 366 m/sec in upper layer suggests weathered soil, the intermediate velocity from 1906 to 2090 m/sec in the medium layer indicates weathered rocks, and the high velocity from 5061 to 5650 m/sec in the lower layer implies extremely hard rocks. Our seismic result suggests that the upper and medium layer around the Maaebul should be reinforced to support the construct. The result of electric resistivity survey shows that there exists a low resistivity zone, ranging from 131 to 226 Ohm-m, at the right side of the Maaebul with the direction of NE-NNE. This area is the weakness zone as it plays role of the underground water passage in rainy season.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.620-634
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• 2018

The NTR(New Tubular Roof) method was used to secure the stability of the tunnel and minimize the subsidence of the road. The tunnel was constructed at about 7.5 meters deep below the highway. with a width of about 21 meters. Following the NTR method, 13 steel pipes with a diameter of 2.3 meters were digged and pushed in longitudinally along the tunnel profile and cut out sides of pipes to connect to adjacent pipes, then filled the inside of pipes and the connected space between pipes with concrete to complete the lining of the tunnel to be excavated. As the steel pipes were digged in sequentially, the area of relaxation was connected to each other and behaves like a gradually widening tunnel. When the steel pipes were digged in to the widest points of the tunnel, the settlement rate of the road surface was increasing to the maximum as 2.2 mm and the total settlement until the lining construction was approximately 7.7 mm. After that, by excavating a tunnel inside the pre-installed lining, an additional settlement of about 4.3 mm was occurred, resulting in the total settlement of about 11.8 mm after completing of tunnel construction.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.386-394
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• 2022

In this study, the mechanical properties and frost resistance of concrete with steel and nylon fibers were experimentally investigated. Both of OPC concrete with 100 % ordinary portland cement and SGC concrete replaced with 50 % GGBFS were manufactured to evaluate effects of fibers to the performance of concrete. Compressive and split tensile strength, ultrasonic pulse velocity and surface electric resistivity measurements of concrete were carried out at a predetermined interval. In addition, the freezing & thawing resistance of concrete in accordance with ASTM C666 standard was also examined. As a result, it is seemed that the effect of fibers was remarkable to improve the mechanical properties and frost resistance of concrete, especially for the concrete incorporating steel fiber.

• Journal of the Korean Geotechnical Society
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• v.28 no.5
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• pp.13-25
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• 2012

Ground anchor method is one of the most popular reinforcing technology for slope in Korea. For the health monitoring of slope which is reinforced by permanent anchor for a long period, monitoring of the tension force of ground anchor is very important. However, since electromechanical sensors such as strain gauge and V/W type load cell are also subject to long-term risk as well as suffering from noise during long distance transmission and immunity to electromagnetic interference (EMI), optical FBG sensors embedded tendon was developed to measure strain of 7-wire strand by embedding FBG sensor into the center king cable of 7-wire strand. This FBG sensors embedded tendon has been successfully applied to measuring the short-term anchor force. But to adopt this tendon to long-term monitoring, temperature compensation of the FBG sensors embedded tendon should be done. In this paper, we described how to compensate the effect in compliance with the change of underground temperature during long-term tension force monitoring of ground anchors by using optical fiber sensors (FBG: Fiber Bragg Grating). The model test was carried out to determine the temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon. The determined temperature sensitivity coefficient ${\beta}^{\prime}=2.0{\times}10^{-5}/^{\circ}C$ was verified by comparing the ground temperatures predicted from the proposed sensor using ${\beta}^{\prime}$ with ground temperatures measured from ground thermometer. Finally, temperature compensations were carried out based on ${\beta}^{\prime}$ value and ground temperature measurement from KMA for the tension force monitoring results of tension type and compression type anchors, which had been installed more than 1 year before at the test site. Temperature compensated tension forces are compared with those measured from conventional load cell during the same measuring time. Test results show that determined temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon is valid and proposed temperature compensation method is also appropriate from the fact that the temperature compensated tension forces are not dependent on the change of ground temperature and are consistent with the tension forces measured from the conventional load cell.