• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.111-119
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• 2016

Rebound hammer test, SonReb method and concrete core test are most useful testing methods for estimate the concrete compressive strength of deteriorated concrete structures. But the accuracy of the NDE results on the existing structures could be reduced by the effects of the uncertainty of nondestructive test methods, material effects by aging and carbonation, and mechanical damage by drilling of core. In this study, empirical procedure for verifying the in-situ compressive strength of concrete is suggested through the probabilistic analysis on the 268 data of rebound and ultra-pulse velocity and core strengths obtained from 106 bridges. To enhance the accuracy of predicted concrete strength, the coefficients of core strength, and surface hardness caused by ageing or carbonation was adopted. From the results, the proposed equation by KISTEC and the estimation procedures proposed by authors is reliable than previously suggested equation and correction coefficient.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.135-140
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• 2005

In case of rock bolt useable by tunnel reinforcement methods at field is applied problem of typical rock bolt pull test diagram method propositional in documents and is not thesis of clearness analysis basis about result of rock bolt pull test. So this paper suggested in consideration of foreign basis and field condition that the first, "suggestion of apposite diagram method at tight ground and difference application of rock bolt pull test method at loose and tight ground" and the second, "thesis of estimation basis non-thesis of design and specification, test etc".

• Journal of the Korean Geotechnical Society
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• v.26 no.1
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• pp.55-62
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• 2010

Dynamic soil resistances were simulated by modified Ramberg-Osgood model in order to predict penetration rate of sheet pile installed by vibratory pile driver. Various factors which characterize modified Ramberg-Osgood model were determined considering the shapes of dynamic soil resistance curves obtained from field test and standard penetration value (N value) was used as parameter that relates field test results to the suggested model. Penetration rates calculated by analytical model were smaller than those of field test and penetration times were vice versa. Therefore, predicted penetration rate and penetration time by analytical model are more conservative than those of filed test.

• Journal of the Korean Geosynthetics Society
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• v.21 no.4
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• pp.1-12
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• 2022

Generally, the plate load test and the field density test are conducted for compaction quality control in earthwork, and then additional analysis. Recently developed that the DCPT (Dynamic Cone Penetration Test) equipment for smart compaction quality control its the system are able to get location and real-time information about worker history management. The IoT-based the DCPT system improved the time-cost in the field compared traditional test, and the functions recording and storage of the DPI (Dynamic Cone Penetration Index) were automated. This paper describes using these DCPT equipment on in-situ and compared to the standards of the DCPT, and the compaction trend had be confirmed with DPI as the field test data. As a result, the DPI of the final compaction decreased by 1.4 times compared to the initial compaction, confirming the increase in the compaction strength of the subgrade compaction layer 10 to 14 cm deep from the surface. A trend of increasing compaction strength was observed. This showed a tendency to increase the compaction strength of the target DPI proposed by MnDOT and the results of the existing plate load test, but there was a difference in the increase rate. Therefore, additional studies are needed on domestic compaction materials and laboratory conditions for target DPI and correlation studies with the plate load tests. If this is reflected, it is suggested that DCPT will be widely used as smart construction equipment in earthworks.

• Journal of the Korean Geosynthetics Society
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• v.20 no.1
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• pp.35-44
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• 2021

This research studies the stabilization method for improved soil sloped through the on-site application of Paper Flyash ground stabilizers. The target strength required for improved soil is 500 kPa, and the compressive strength for the slope surface needs to be less than 1,000 kPa after the improvement in order to plant vegetation. To meet this condition, we mixed soil from the site and the ground stabilization material, which is the main material for surface improvement material, performed mixing design and conducted various tests including strength test, permeability test and plantation test. After analyzing the results of the compression test on improved soil slope, we proposed soil constants for the improved soil. In order to evaluate the applicability of the improved soil on the slope, the site construction was carried out on the collapsed slope and the reinforcement evaluation of the surface of the improvement soil was conducted. The stability was not secured before the reinforcement, but the test shows after the reinforcement with improved soil, the safety rate is secured up to 48 hours during the raining period. In addition, the compressive strength of the improved soil at the site was secured at more than 200 kPa adhesion as planned, and the soil hardness test result was also found to be within the specified value of 18-23 mm, which increased the resistance to rainfall and ability to grow plant on the surface for improved soil.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.10a
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• pp.236-241
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• 1999

산업이 발전해 가며 공장 자동화를 하는 회사는 나날이 늘어가고 있으며 현재 산업 전반에 걸쳐 자동화 시스템을 채택하지 않는 곳을 찾아보기 어렵고 이 시스템의 시험 및 운영자 교육용으로 시뮬레이터에 대한 관심은 높아 가고 있는 실정이다. 여기에서는 한국전력에서 사용하고 있는 터빈 제어 삼중화 시스템이 어떠한 보팅 기법들을 적용하여 설계되었으며 그 기능이 어떻게 구현되었는지를 실제 제품의 사례분석을 통해 검토해 보고자 한다. 검토 대상은 삼중화 제어기에 대해서만 시행할 예정이다. 이는 실제 현장이 경제성을 수반한 제어기의 신뢰, 이용, 안정, 수행, 지속, 시험, 확실성 등을 원하고 있으며 또한 시뮬레이터를 설계하는 사람들에게 삼중화 주제어기에 대한 비교(MARK-V, Triconex-TMR, GE-Fanuc, Woodward-Micronet) 소개함으로서 더욱더 현장과 가까운 시뮬레이터를 설계할 수 있도록 하기 위함이다.

• Journal of the Korean Geotechnical Society
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• v.26 no.11
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• pp.111-123
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• 2010

The steel pipe of steel-concrete composite drilled shafts increases the pile strength and induces the ductile failure by constraining the deformation of the inner concrete. In this research, pile loading tests were performed to analyze the field applicability of a steel-concrete composite drilled shafts. The test ground consisted of 5~7 m thick soil underlying rock mass. The test piles consisted of two steel-concrete composite drilled shafts, which were the concrete filled steel pipe piles with the diameter of 0.508 m, and a concrete pile with the same diameter. The test results showed that the boundary between the upper steel composite section and the lower concrete section was structurally weak and needs to be reinforced by using a inner steel cage. If the boundary is located in deep depth, which is not influenced by lateral load, the allowable strength of the lower concrete section increases, so an economical design can be performed by increasing the design load of steel-concrete composite drilled shafts.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.5
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• pp.526-531
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• 2003

Condition assessment of concrete structures is essential since their performance affects public safety. Impact resonance testing has been widely used for the nondestructive testing of the concrete structures. In this article, the background, basic principles of the impact resonance testing were described. Not only laboratory studies but also the field applications such as basement concrete of large structure and large slurry wall are described.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.649-653
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• 2012

제방붕괴에 따른 피해발생을 억제하기 위해서는 제방거동 특성을 사전에 충분한 정보를 통하여 파악할 필요가 있으며, 이를 위해 광섬유를 이용한 제방누수감지 센서를 개발하였다. 광섬유는 내구성 및 유지관리가 우수하고 장기간 사용에도 장점을 가지고 있다. 개발된 센서들은 현장에 적용하기 전에 충분한 실험을 통해 성능과 기능에 대한 검토가 필요하다. 본 연구에서는 개발된 광섬유 센서를 대상으로 제방누수감지 목적으로 설치할 경우 센서의 이행도를 시험하였다. 시험방법은 토조를 설치하여 제체에 작용하는 간극수압, 온도 및 변위 등을 대상으로 하였다. 이를 위해 폭 5m, 길이 7m 및 높이 2m의 토조를 설치하여 가제방의 주요 부위에 기존 계측기기와 광섬유 센서를 같이 매설하고 수위와 시간변화에 따른 주요 특성치에 대하여 실험하였다. 실험결과 광섬유 센서가 연구목적에 부합하는 계측치를 보여주어 제방누수감지 센서로 활용 가능함을 확인하였다. 아울러 광섬유 센서의 기능에 대한 전반적인 실험을 통하여 현장적용에 대한 사용성을 입증하였다.

• Journal of the Korean Geotechnical Society
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• v.25 no.4
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• pp.55-68
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• 2009

A new borehole roughness and verticality measurement system (BKS-LRPS) for rock socketed drilled shafts were developed and verified its field application. The stability of BKS-LRPS was verified for several field conditions, which included the effect of measuring unit shaking, the application of water/air calibration factors, and the resistance of high water pressure inside piles. Also, effective measurement distances for various conditions of turbidity were defined in the field by measuring borehole roughness and vertical alignment for 6 drilled shafts. Vertical alignments for all drilled shafts could be measured by BKS-LRPS. However, borehole roughness was not able to be measured due to high turbidity caused by RCD drilling processing. Based on the BKS-LRPS field verification, BKS-LRPS is the first borehole roughness and verticality measurement system applying both in the water and air.