• 한국농공학회지
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• 제17권3호
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• pp.3848-3859
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• 1975

The author attempted to find most suitable formulas for probable rainfall intensities with analysis and consideration for characteristics of rainfall intensities according to the short and long period return periods at Cheong-Joo district. Above mentioned formulas induced by this study can be contributed to the credibility of runoff estimation for urban sewerage system, drainage works in small catchment area and embankment works in the rivers. The results of this study are summarized as follows: 1 Calculation values by Gumbel-Chow method were selected as a mean values for the calculation of probable rainfall intensities according to return periods in the short period. 2. Calculations for probable rainfall intensities for long period are based upon to the result by Iwai's method. Talbot type, {{{{I= {a} over {t+b} }}}} is confirmed as a most suitable formula for probable rainfall intensities among calculation methods in the short periods at Cheong-Joo district. 4. Specific coefficient method, I24=RN24${\beta}$N was selected as a means of calculation for suitable formulas of probable rainfall intensities according to return periods in case of long period. 5. Runoff estimation with high credibility by rational formula can be anticipated by establishment for the most suitable probable rainfall intensities at Cheong-Joo district.

• 한국환경복원기술학회지
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• 제17권6호
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• pp.39-50
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• 2014

This study was conducted to establish inventory and propose conservation strategy of 'village wetlands' in Cheonan. As results, the village wetlands are defined as such places as palustrine wetland, village embankment, agricultural reservoir or small reservoirs located in or near the village and related to everyday life or farming. Firstly 791 provisional village wetlands were identified in Cheonan by using Arc-GIS 10.1, then 104 wetlands were defined as village wetlands and listed the inventory of Cheonan Village Wetlands after being validated through their area (greater than $1,000m^2$), satellite images, Korea Land Information System, land use map, land coverage map and field survey. Finally the 49 wetlands were selected for detailed surveying, and function assessment. As the result of the wetland function assessments, 11 wetlands were found to have 'high' wetland function (conservation) 30 wetlands were 'average' (enhancement) and 8 wetlands were 'low' (restoration or enhancement). Enhancing biodiversity and ecosystem services through ecological management of wetlands in Cheonan and connecting with an ecological network were proposed.

• 한국지반신소재학회논문집
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• 제15권4호
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• pp.1-8
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• 2016

이 연구의 목적은 소다회 생산과정에서 발생한 매립지의 압밀특성을 연구하는데 있다. 소다회를 생산하는 과정에서 발생하는 부산물의 주요성분은 대부분 석회석이다. 이 연구는 우선 폐석회의 압밀특성을 파악하기 위해 시추조사를 통한 불교란 시료를 채취하여 실내실험을 실시하였다. 실험결과 폐석회는 소성이 큰 유기질토로 분류되었으며, 유기물 함유량 시험결과 폐석회에 함유된 유기물 함량은 일반 점토에 비하여 높게 나타났다. 또한, 이론적인 방법과 압밀해석 프로그램에 의하여 폐석회의 압밀침하량과 이차침하량을 산정하였다.

• 한국농공학회지
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• 제34권1호
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• pp.87-99
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• 1992

A mathematical model, UNSATR which predicts the seepage flow through the body of dike especially under the tidal fluctuation has been developed. This model has been revised from UNSAT2 model which was developed on the basis of the saturated-unsaturated theory by Neuman. UNSATR has been verified and applied to the hydraulic model in order to estimated the seepage quantity, the formation of free water surface etc. The results lead to the following conclusions : 1. Seepage rates between the mathematical model and hydraulic model experiment are very similar to each other both in constant and transient water level conditions. 2. The lapsed time to be steady state of the free water surface becomes late as the tidal levels are relatively low mainly due to the seepage flow from the unsaturated zone of the body of dike. 3. Under the transient state of water levels, owing to the flow from the unsaturated domain, streamlines crossing to the free water surface are found and time lag during a falling tide may allow the free water surface inside the body of dike to stand at a high level than the outside water level. 4. The utility and validity of UNSATR model are convinced when the analyses on seepage problems through the porous embankment of the soil structures on the conditions of the steady and unsteady states are carried out.

• 한국농공학회지
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• 제25권4호
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• pp.69-79
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• 1983

The objective of this study is to analyze the present situation of compaction equipment used in the earth fill dam construction, and the compaction effects of varions types of equipment on core and pervious zones of the fill dam. The results obtained are summarized as follows; 1. Banking materials mostly used for the core zone were soils classified as CL, SC and ML, while those classified as SM, ML and SC were predominant for the pervious zone. 2. Equipments used practically in the real fields were considerably different from those specified in the designs. 3. It was found that the relationship between optimum water content and maximum dry density for both core and pervious materials showed to be linear, ranging from 10% to 25% water content. That is, ${\gamma}$dmax (core) = 2.2555-0.0284 Wopt ${\gamma}$dmax(pervious) =2.239-0.028 Wopt 4. The generalized compaction guides for all kinds of equipment and soil types consi- dered in this study may be recommended as N=8-10 T=2Ocm, N=10-12 T=3Ocm for core zone(98%) and N=6-8 T=2Ocm, N=8-10 T=3Ocm for pervious zone (95%). 5. The coefficient of permeability in the field tests showed abont 10 times as high as the laboratory test value. This large deviation, however, was due to the horizontal permeation and considered not to be significant in the light of the satisfactory compaction ratio in the field compac- tion.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.477-483
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• 2000

Fly ash is the unburned residue resulting from the combustion of coal in utility and industrial boilers such as thermal power plants. Annually about 5 million tons of fly ash is being produced in korea. Less than 25 percent of total volume of fly ash is currently being used effectively for some ways. In the future, the volume of fly ash discharge from thermal power stations will be increasing more and more, and the development of the utilization of high volume fly ash is required. Fly ash has a lower compacted density and specific gravity than coarse grained natural aggregates but equivalent strength properties indicating that the fly ash could be used as a structural fill materials. So, clay-fly ash mixtures can be used as a fill material in the construction of embankments. Laboratory tests have been carried out to determine the physical, chemical, and geotechnical characteristics of the clay and fly ash. The fly ash is mixed with the clay in different proportions and the geotechnical characteristics of the mixtures have been studied also. In this study describes the results of the experimental study. The implications of the use of clay and clay-fly ash mixtures on the stability of embankments are discussed.

• Geomechanics and Engineering
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• 제10권5호
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• pp.689-707
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• 2016

Soil stabilization is one of the useful method of ground improvement for soil with low bearing capacity and high settlement and unrequired swelling potential. Generally, the stabilization is carried out by adding some solid materials. The main objective of this research was to investigate the feasibility of stabilization of organic soils and sewage sludge to obtain low cost alternative embankment material by the addition of two different slags. Slags were used as a replacement for weak soil at ratios of 0%, 25%, 50%, 75% and 100%, where sewage sludge and organic soil were blended with slags separately. The maximum dry unit weights and the optimum water contents for all soil mixtures were determined. In order to investigate the influence of the slags on the strength of sewage sludge and organic soil, and to obtain the optimal mix design; compaction tests, the California bearing ratio (CBR) test, unconfined compressive strength (UCS) test, hydraulic conductivity test (HCT) and pH tests were carried out on slag-soil specimens. Unconfined compressive tests were performed on non-cured samples and those cured at 7 days. The test results obtained from untreated specimens were compared to tests results obtained from soil samples treated with slag. Laboratory tests results indicated that blending slags with organic soil or sewage sludge improved the engineering properties of organic or sewage sludge. Therefore, it is concluded that slag can be potentially used as a stabilizer to improve the properties of organic soils and sewage sludge.

• Geomechanics and Engineering
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• 제18권5호
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• pp.493-502
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• 2019

Internal stability is an important safety issue for levees, embankments, and other earthen structures. Since a large part of the world's population lives near oceans, lakes and rivers, floods resulting from breaching of dams can lead to devastating disasters with tremendous loss of life and property, especially in densely populated areas. There are some main factors that affect the internal stability of dams, levees and other earthen structures, such as the erodibility of the soil, the water velocity inside the soil mass and the geometry of the earthen structure, etc. Thus, the mechanism of internal erosion and stability of soils is very complicated and it is vital to investigate the assessment methods of internal stability of soils in embankment dams and their foundations. This paper presents an improved support vector machine (SVM) model to predict the internal stability of soils. The grid search algorithm (GSA) is employed to find the optimal parameters of SVM firstly, and then the cross - validation (CV) method is employed to estimate the classification accuracy of the GSA-SVM model. Two examples of internal stability of soils are presented to validate the predictive capability of the proposed GSA-SVM model. In addition to verify the effectiveness of the proposed GSA-SVM model, the predictions from the proposed GSA-SVM model were compared with those from the traditional back propagation neural network (BPNN) model. The results showed that the proposed GSA-SVM model is a feasible and efficient tool for assessing the internal stability of soils with high accuracy.

• 한국건설순환자원학회논문집
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• 제4권1호
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• pp.76-81
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• 2016

순환골재는 천연골재가 부족한 국내에서 매우 유용한 골재자원이며, 정부에서도 이러한 중요성을 인식하고 순환골재의 고부가가치 활용을 위한 다양한 정책을 제안하고 있다. 그러나 현재 국내에서 생산되는 순환골재는 대부분 성토, 매립 등 저부가가치의 용도로 활용되고 있으며 구조용 부재와 같은 고부가가치 활용은 아직 이루어지지 않고 있다. 국내 순환골재 생산기술은 세계적인 수준임에도 불구하고 순환골재콘크리트의 구조용 부재적용은 아직 이루어지지 않고 있으며 이는 순환골재의 표면에 부착된 부착모르타르와 순환골재의 생산과정에서 발생되는 균열로 인해 순환골재콘크리트의 품질을 예측하고 조절하기 어렵기 때문인 것으로 판단된다. 본 연구에서는 순환골재콘크리트의 현장적용성 증진을 위한 일환으로 순환골재, 조강시멘트, 증기양생 최고온도 및 최고온도 지속시간이 순환골재콘크리트에 미치는 영향을 분석하고자 하였다.

• 한국지반공학회논문집
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• 제36권3호
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• pp.5-14
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• 2020

콘크리트궤도는 고속, 고밀도의 운행선로에서도 차량의 주행안정성이 높고, 이용승객에게 좋은 승차감을 제공할 수 있으며, 궤도 보수 비용을 대폭 절감시킬 수 있는 장점을 가지고 있어 고속선을 중심으로 점차 적용 구간이 늘어나고 있다. 하지만, ◯◯고속철도 토공 구간의 노반 침하로 기인된 콘크리트궤도의 2차적 침하가 발생하는 사례가 빈번히 발생하고 있어, 이로 인한 철도 운행의 안정성 문제가 대두되고 있다. 허용 잔류침하량을 초과하는 콘크리트궤도에 대한 효율적인 유지보수 방안 수립을 위해서는 공용 기간 중 발생하는 콘크리트궤도의 장기 침하 거동을 합리적으로 예측하는 것이 필수적이다. 따라서, 본 연구에서는 다양한 인공지능 기술 중 순환신경망을 활용하여 콘크리트궤도의 장기 침하 거동을 예측하는 모델을 개발하였다. 또한 기존 모델의 침하 예측 결과와 비교를 통해 개발된 모델의 적용 가능성을 모색하였다.