• Journal of The Korean Society of Grassland and Forage Science
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• v.4 no.2
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• pp.108-114
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• 1983

This study was conducted to investigate the effects of existing vegetation on seedling establishment and herbage production of oversown grasses in the Pinus rigida forest. The dominant existing vegetations were Miscanthus sinensis, Festuca ovina, and Lycopodium serratum. In establishment year, seedling stands and herbage production were not affected in Miscanthus sinensis and Festuca ovina, while in Lycopodium serratum it was affected relatively seriously. The pattern of sown species response to the existing vegetations was trend to toward simplified two or three species as Dactylis glomerata, Lolium perenne, and Trifolium repens to advancing the time. Among sown species, Dactylis glomerata was a major dominant species in all existing vegetation area. The content of sown pasture grasses in the sward increased markedly, while the existing vegetations before seeding seriously decreased to advancing the cutting time. The above results shown that the improvement of forest pasture with a surface seeding was better in Miscanthus sinensis and Festuca ovina, but in Lycopodium serratum was found very difficult to improvement of pasture without surface treatment, also establishment method must favor the low herbage production potential.

• Journal of the Korean Geosynthetics Society
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• v.18 no.3
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• pp.1-9
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• 2019

In this study, the effect of ground improvement was to be verified by granular compaction pile from the ground reclaimed with Fly Ash landfill site. The depth and strength parameters of the Fly ash layer was determined using the ground investigation and cone penetration test. And the STONE C program was used to predict the strength parameter, bearing capacity and settlement of the improved ground. As a result of the plate bearing test, the bearing capacity of improvement ground was higher than the design load and the settlement was smaller than the reference value. After the construction, the improvement effect by the cone penetration test was confirmed. The cone penetration resistance value($q_c$) increased by 250% to 500% and the effect was excellent.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.621-626
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• 2005

A major part of permanent way maintenance effort is justified by inadequacies in the track substructure and in particular in drainage conditions, which need to be put right across the entire network. In most cases nowadays, improvements of the substructure can be carried out on rail to a high standard of quality. However, this entails substantial movements of material for the removal of spoil and provision of new material. In the future, recycling of old material on site, and use of geosynthetics, will be necessary to help considerably reduce this volume.

• Journal of the Korean Geotechnical Society
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• v.33 no.5
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• pp.5-13
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• 2017

The sand layer deposited in clay is called a sand seam, which is formed by inflow of sands due to river flooding or slope failure in the middle of sinking and sediment of clay. When the sand seam exists in clay layer, the drainage direction changes from one way to both ways, and the time of consolidation may be reduced. However, it is not clearly proved due to lack of studies of sand seam and currently is not reflected in the design of soft soil improvement. As a fundamental study about sand seam, the oedometer tests and constant rate of strain tests with Rowe cell were conducted on clay specimens with sand seam. For tests, a frozen method was specially designed for making the sand seam. It was concluded that the test results showed the sand seam affects the coefficient of consolidation of clay. If the thickness of sand seam exceeds 0.05 times of specimen height, the sand seam works as drainage layer of pore water horizontally as well as vertically, and consequently the consolidation is accelerated.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.3-8
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• 2002

본 연구는 트랙터 부착형 자동 토양경도 측정 시스템의 개발에 관한 연구로서, 우리나라 토양조건이나 작업형태에 맞는 에너지 절감형 트랙터 로타리날을 개발하기 위한 전단계 연구로서, 기존에 개발된 로타리날과 개량, 보완되어 개발될 로타리날의 성능을 비교 분석하기 위하여 수동 토양경도 측정기의 부정확성을 개량하여 측정의 정확성을 통한 동일 실험조건에서의 실험을 실시하고자 자동으로 작동되며 토양경도측정을 할 수 있는 트랙터 부착형 자동 토양경도 측정 시스템을 개발하는데 목적이 있으며, 그 구체적인 연구 결과는 다음과 같다. (1) 시스템은 토양경도 측정부, 측정장치 구동부, 그리고 트랙터와의 연결부로 구성되었다. (2) 시스템 작동에 필요한 전원공급을 트랙터 배터리에서 공급하였다. (3) 토양경도 측정시 토양속에 돌이나 이물질 층이 형성되어 있는 경우에 콘 페니트로메타가 관입하다가 큰 관입저항 때문에 관입저항 한계설정치까지 가기전 더이상 관입을 못하는 경우가 발생하였다. (5) 성능실험시 관입심이 깊을수록 시험포장 전체에서 대체적으로 토양경도가 높은 것으로 나타났으며, 토양속의 돌이나 이물질 등에의해 경도가 급격히 증가하는 부분이 있는 것으로 사료된다. 이상의 결과에서 살펴보면 본 시스템은 토양경도 측정에 적절하다고 사료된다.

• Journal of IKEEE
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• v.26 no.4
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• pp.560-567
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• 2022

This paper proposed an application of agile management method to resolve the electrical system issues identified during the mass production phase of aged aircraft performance improvement. The proposed method was applied from issue analysis to on-site verification and testing stage, before the formal configuration control process. At this time, the project was carried out by setting a sprint period to complete the verification according to requirements through daily scrum and sprint review. As a result, It was verified that the wiring installation of the aircraft, which was the output of the sprint, met requirements within the defined sprint period.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.53-67
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• 2001

In this study the pilot test of CGS as injection method by low slump mortar was performed and the results were analyzed in order to find out the application of this method and effect of settlement restraint. The site far pilot test is adjacent to apartments supported by pile foundations. Sand drain method was performed previously as countermeasures against settlement, but settlement occur continuously because this ground is very soft. Site investigations such as SPT, DCPT and vane shear test were performed to determine the characteristics of ground improvement. Field measurements and FDM analysis were performed on purpose to find out the displacement of ground during injection works. From the results of this study, CGS method can be optimized by the control of diagram, space, depth, injection material, and injection pressure. CGS improved soft ground compositely by the bearing effect of CGS columns and reinforcement of adjacent ground. Considering that increase of N value is about 2.1, CGS can be considered as an effective method to increase the bearing capacity as well as to stop the settlement of soft ground. It is also expected to be economic and effective in improvement of ground when it is used in applicable sites.

• Journal of the Korean Geotechnical Society
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• v.15 no.3
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• pp.3-16
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• 1999

A series of model tests was conducted to investigate the one-dimensional consolidation behavior of an improved ground where sand compaction piles(SCP) were either fully or partly installed in the model clay ground. In order to check the one-dimensional consolidation settlement and stress concentration ratios, earth pressure, pore pressure transducers and dial gauges were installed in the model clay ground. The test results revealed that the consolidation settlement of the partly penetrated SCP ground was larger than that of the fully penetrated SCP ground, and the stress concentration ratios (m) of the fully penetrated SCP ground were higher than these of the partly penetrated SCP ground. The stress concentration ratio was decreasing with the increase in the penetration depth of SCP.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.605-610
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• 2011

Soft ground improvement is essential to enhance strength of ground for construction in reclaimed land or shore. There are many method of soft ground improvement, and vertical drain method was widely used in many countries including korea. As vertical drain method is to plant many Prefabricated Vertical Drains in soft ground, it promotes consolidation and enhances strength. The PBD(Plastci Board Drain) that is excellent economy and workability was widely used in many countries as Prefabricated Vertical Drains. Construction quality of PBD is affected installation depth, pressure, perpendicularity. This paper describes the system developed that can automatically measure installation depth, pressure and perpendicularity for PBD. This system can reduce fraction defective of construction by auto faulty alarm and keeps the safety of operator by auto control system.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.119-131
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• 2014

For quick and accurate ground investigation in wide construction site being not easy to access, advanced dynamic cone penetration test equipment was developed based on widely used equipment abroad. Advantages of existing equipment of portability and simple testing method were reflected in the new developed equipment. Meanwhile, by extending connection of lower rod, penetration depth is raised to 6m from 1 m of the existing equipment. Moreover, by assembly of hammer (2+3+3kg) and cone (3 types) etc., it is possible to perform test under the same conditions with those by German and Japan dynamic cone penetration test equipment (Tsukuba, PWRI and SH types). Auxiliary equipment was applied to make sure of perpendicularity as penetration depth increases. Applicability of the new developed equipment was evaluated through tests on various fields and its reliability was verified.