• 한국지반공학회논문집
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• 제20권3호
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• pp.107-117
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• 2004

본 연구에서는 폐타이어를 활용하여 새롭게 고안한 타이어셀 매트의 모래지반 보강효과를 알아보기 위하여 다양한 조건의 평판재하시험을 수행하였다. 계하시험조건은 셀 간의 연결을 위한 볼트 수, 상대밀도, 복토두께, 보강층수, 타이어셀 매트 폭을 변수로 보강효과를 조사하였다. 재하시험 결과 연결용 볼트의 수는 지지력에 큰 영향을 미치지 않는 것으로 나타났으며 1개의 볼트로 주어진 하중을 충분히 견딜 수 있었다. 보강토의 극한지지력과 무보강토의 극한지지력의 비로 정의되는 지지력비(BCR)는 낮은 밀도에서 최대값을 나타내었다. 또한 극한상태에서의 침하감소효과도 낮은 밀도에서 큰 것으로 나타났다. 복토에 따른 보강효과는 복토두께가 1.0B이내에서 보강효과를 얻을 수 있었으나 그 이상에서는 보강효과가 나타나지 않았다. 보강층의 간격이 재하판폭의 0.4내지 0.5배일 경우 보강효과는 보강층이 2층일 때까지는 보강효과가 있으나 3층 이상에서는 효과가 없는 것으로 나타났다. 특히 보강층이 1개층일 때 지지력 증가 효과가 크며 2개층으로 증가함에 따라 증가율은 저하되는 것으로 나타났다. 타이어셀 매트폭이 2.0B에서 최대지지력을 보였으나 매트폭의 영향은 타이어셀의 강성이 크기 때문에 미소하였다. 타이어셀 매트의 지반보강효과는 문헌상의 상업용 지오웹과 비교하여 뛰어난 것으로 나타났다.

• 한국농공학회논문집
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• 제53권4호
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• pp.29-37
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• 2011

Effect of rice straw mat and wood shaves on the reduction of runoff and nonpoint source (NPS) pollution loads from field plots were experimentally studied. Three runoff plots of $5{\times}22$ m in size and 3 % in slope were prepared on a loamy sand field. Each plot was equipped with a flume to measure runoff and collect water samples. Experimental treatments of surface cover were bare, wood shaves (1,000 kg/ha) and rice straw mat cover (3,000 kg/ha). Under radish was cultivation. During the growing season of the radish, three rainfall-runoff events were monitored. Effect of wood shaves and straw mat cover on runoff reduction was 4~30 % and 33~75 % respectively compared to control. The effect on NPS pollution reduction was 36.8 and 64.3 % in BOD, 41.1 and 80.8 % in SS, 34.0 and 56.1 % in TP and 28.0 and 56.6 % in TN respectively. It was analyzed that the reduction of runoff and NPS pollution were mainly contributed by the decrease of rainfall energy impact and flow velocity and the increase of infiltration due to the surface cover materials. Rice straw mat showed very stable soil cover while large portion of wood shaves were lost during heavy storm events. It was concluded that straw mat was an efficient cover material to reduce NPS pollution from upland fields.

• 한국재료학회지
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• 제31권2호
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• pp.75-83
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• 2021

To cope with automobile exhaust gas regulations, ISG (Idling Stop & Go) and charging control systems are applied to HEVs (Hybrid Electric Vehicle) for the purpose of improving fuel economy. These systems require quick charge/discharge performance at high current. To satisfy this characteristic, improvement of the positive electrode plate is studied to improve the charge/discharge process and performance of AGM(Absorbent Glass Mat) lead-acid batteries applied to ISG automotive systems. The bonding between grid and A.M (Active Material) can be improved by applying the Sand-Blasting method to provide roughness to the surface of the positive grid. When the Sand-Blasting method is applied with conditions of ball speed 1,000 rpm and conveyor speed 5 M/min, ideal bonding is achieved between grid and A.M. The positive plate of each condition is applied to the AGM LAB (Absorbent Glass Mat Lead Acid Battery); then, the performance and ISG life characteristics are tested by the vehicle battery test method. In CCA, which evaluates the starting performance at -18 ℃ and 30 ℃ with high current, the advanced AGM LAB improves about 25 %. At 0 ℃ CA (Charge Acceptance), the initial charging current of the advanced AGM LAB increases about 25 %. Improving the bonding between the grid and A.M. by roughening the grid surface improves the flow of current and lowers the resistance, which is considered to have a significant effect on the high current charging/discharging area. In a Standard of Battery Association of Japan (SBA) S0101 test, after 300 A discharge, the voltage of the advanced AGM LAB with the Sand-Blasting method grid was 0.059 V higher than that of untreated grid. As the cycle progresses, the gap widens to 0.13 V at the point of 10,800 cycles. As the bonding between grid and A.M. increases through the Sand Blasting method, the slope of the discharge voltage declines gradually as the cycle progresses, showing excellent battery life characteristics. It is believed that system will exhibit excellent characteristics in the vehicle environment of the ISG system, in which charge/discharge occurs over a short time.

• 한국지반환경공학회 논문집
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• 제13권6호
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• pp.83-90
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• 2012

일반적으로 심층혼합공법에 의한 점토지반의 개량효과는 물리적 개량효과에 비해서 훨씬 크며 조기에 큰 개량 강도를 얻을 수 있으나, 국내 시공실적이 부족하고 시멘트-점토의 혼합방법에 따른 품질관리에 문제점이 있는 것으로 알려져 있다. 본 연구에서는 시멘트, 모래, 점토의 배합비에 따른 강도특성과 연직MAT의 형태에 따른 연약지반의 개량특성을 파악하기 위해 해성점토를 이용하여 일축압축 강도시험과 모형토조시험을 수행하였다. 일축압축강도 시험을 위한 공시체는 시멘트와 물의 중량비를 기준으로하여 모래를 일정 비율로 혼합하였고, 시멘트는 점토중량대비 각각 10%, 20%, 30%, 40%를 혼합하였고 대상지반토의 함수비는 40%, 60%, 80%로 조정하여 제작하였다. 공시체는 습윤방법을 이용하여 7일, 14일, 28일간 양생하여 양생기간에 따른 일축압축강도시험을 수행하였다. 지지력시험은 모형토조를 제작하고 Mat식으로 개량한 지반을 형성한 다음 개량률에 따른 지지력을 비교하고 연직MAT 장벽 상호간의 간섭효과를 분석하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.203-210
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• 2004

Consolidation properties were analysed by means of depositional environments. Depositional environments including geochemical properties, porewater chemistry, sediment structures, particle size distributions and carbon age dating were analysed using undisturbed samples retrieved successively from a boring hole in the study area. Laboratory oedometer tests and anisotropic consolidated triaxial tests(CKoUC) were performed to examine the overconsolidation phenomenons. Based on the carbon age dating results and profiles of geochemical properties, porewater chemistry, salinity and pH, it was founded that the upper silt/clay complex layer was deposited under marine condition while sand and clay layers were deposited under fluvial condition. Planar laminated structures of silts and clays were dominant in marine deposits. Although there was no clear evidences that geological erosion had been occurred in marine deposits, overconsolidation ratio obtained from oedometer tests were greater than unity. Stress paths of samples behaved similar to those of normally consolidated clays. Data plotted in stress state charts proposed by Burland(1990) and Chandler(2000) showed that the marine deposits were geologically normally consolidated. These apparent overconsolidations can be explained by the fabric and chemical bonding due to the difference of the rate of deposition.

• 한국지반신소재학회논문집
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• 제16권1호
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• pp.53-61
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• 2017

바다 자원의 조성을 위해 시설되는 인공어초는 해저 연약지반에 설치될 경우 침하 및 세굴에 의한 기능 상실이 발생할 수 있다. 따라서 본 연구에서는 해저 연약지반의 보강에 따른 인공어초의 침하 거동을 알아보기 위해 모래, 실트 및 점토 지반을 각각 조성하여 관입실험, 침하실험 등과 같은 다양한 실내실험을 수행하였다. 무보강(unreinforced), 지오그리드(geogrid) 보강 및 하이브리드 대나무매트(hybrid bamboo mat, HBM) 보강과 같은 3종류의 보강과 보강재의 면적에 따른 특성을 살펴보았다. 실험 결과 보강재의 면적이 증가할수록 보강 효과가 증가하는 경향을 보였으며, HBM이 지오그리드 단일 보강에 비해 더 뛰어난 보강 효과를 보였다.

• ALGAE
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• 제21권2호
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• pp.235-243
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• 2006

Benthic sediment samples ranging from poorly aggregated sand to complex, stratified mats were collected from six hypersaline ponds from March and July 1995 in the British Virgin Islands. Assemblages were analyzed with respect to species composition and abundance within visibly distinct layers in each mat sample. In individual ponds there was no apparent association between changing depth and the development of the benthic mats. Some species were present in all samples (e.g. Oscillatoria sp.) while others were restricted to single sites (e.g. Johannesbaptistia pellucida). Primary species included Microcoleus chthonoplastes, Phormidium spp., Coccochloris stagnina, and purple sulfur bacteria. Quantitative analysis of community structure included cluster and principal component analysis. Samples from individual ponds were often clustered; however, this was subject to seasonal variation. Mats collected in March were generally thicker and contained more layers than those in July. Variation among sites was not explained by the measured variation in environmental factors such as average pond salinity, depth, and oxygen concentration (mg/L). This study provides a detailed analysis of mat communities in hypersaline ponds and compares them with similar mat communities from other areas.

• 한국농공학회논문집
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• 제54권1호
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• pp.39-45
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• 2012

In this study, field test on utilization of recycled aggregates and crushed stone as horizontal drains to use an alternative material of sand in soft ground is practiced. The settlement with time showed similarly ranged from 28.4-30.3 cm in the all horizontal materials. The excess pore water pressure of the recycled aggregates and crushed stone showed smaller than sand. The small the excess pore water pressure becomes faster the consolidation period and it can reduces the amount of residual settlement. Therefore, it was verified as having enough to an alternative materials that the field applicability is excellent. The distribution of earth pressure with time showed similarly in the all horizontal materials. The recycled aggregates and crushed stone was very applicable to practice because there is no mat resistance in the horizontal drains layer. The penetration rate in the SCP and PVD improvement sections did not show large differences as the grain size and the horizontal drainage height increases.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.569-576
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• 2002

Recently, the hydraulic fill method is commonly used in many reclamation projects due to lack of fill materials. The method of hydraulic fill in reclamation is executed by transporting the mixture of water-soil particles into a reclaimed land through dredging pipes, then the dredged soil particles settle down in the water or flow over an out flow weir with the water. In the present study, to compare the soil and sand-mat mixed method with sand-air jet method for shallow improvement of hydraulic fills at southern seashore, the model tests were performed. Through the model test results, the behavior of surface as disturbance of desiccation crust is analyzed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.672-679
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• 2008

During recent years, the large soft ground improvements very rapidly increase with industrial development and it is the types and scales of structure that is enlarged by degree. Then, we must enter construct equipment to improve soft ground and we fulfilled works by carrying out soft clay soil to gain trafficability for them. For improving the soft ground, we lay geotextile on soft clay ground and fill the filter sand that can drain the pore water. Then, we landfill cover soil for come by trafficability of construction tools. Ater that we penetrate vertical drain for dehydration through soft ground. there are very complicated works. For these reason we suggest the methods of soft ground improvement constructions.