• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.173-174
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• 2023

In this study, unit-water content was measured using a frequency domain reflecometry(FDR) sensor that complements the problems of the existing unit-water content measurement method to evaluate the unit-water content affecting the workability, durability, and quality of high strength concrete. The experiment used the unit-water content of high strength concrete as a variable, and the accuracy and probability distribution of the unit-water content measured through deep learning were analyzed for the output value output through the FDR sensor. In the case of the unit-water content predicted by deep learning analysis, a high accuracy and high distribution of more than 93% were found within the error range of ± 10 kg/m³. In the future, research is needed to secure high reliability by utilizing data obtained through experiments with various variables.

• 한국환경복원기술학회지
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• 제9권1호
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• pp.72-88
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• 2006

The optimal environmental ranges of the establishment phase for the distribution of Zizania latifolia and Typha angustifolia was determined to develop a set of basic data and criteria of planting substrate for the restoration, conservation and management of wetlands. The study was carried at 17 wetlands in the Kyunggi-do and Gyeongsangnam-do region where inland wetlands place intensively in June, 2005. Total 127 quadrats were sets in growing areas of Zizania latifolia and Typha angustifolia. $NO_3-N$, K, Ca, Mg and Na in the water variables and soil texture, LOI (loss on ignition), soil pH and soil conductivity in the soil variables were analyzed. The optimal range of water depth for the distribution of Zizania latifolia was -5~39cm, $NO_3-N$ content of water was <0.01~0.19ppm, K content of water was 0.1~5.9ppm, Ca content of water 0.5~44.9ppm, Mg content of water was 1.2~11.9ppm, Na content of water 3.4~29.9ppm, water conductivity was 48~450${\mu}S$/cm, respectively. The optimal range of LOI for the distribution of Zizania latifolia was 1.7~11.9%, soil conductivity was 25.5~149.9${\mu}S$/cm, respectively. The optimal range of water depth for the distribution of Typha angustifolia was -20~24cm, $NO_3-N$ content of water was <0.01~0.19ppm, K content of water was 0.2~2.9ppm, Ca content of water 0.6~19.9ppm, Mg content of water was 0.2~5.9ppm, Na content of water 3.5~19.9ppm, water conductivity was 96~450${\mu}S$/cm, respectively. The optimal range of LOI for the distribution of Typha angustifolia was 2.4~15.9%, soil conductivity was 17.6~149.9${\mu}S$/cm, respectively. The optimal soil texture were loam, silt loam and sandy loam in both species. The lower water depth (-20~40cm) is appropriate to increase biodiversity in both species dominated community and it is better to maintain water depth of 40~100cm for water purification. Both species appear frequently in the soil with high silt content.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.341-346
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• 2002

This study is intended to check the possibility to estimate water content by heat-drying method with variation of W/C and slump. According to the results, in case of electric range method, when water content is less than 165kg/m$^3$ in mixture, it is estimated more and in more than 165kg/m$^3$, it is estimated less. It shows that water content in gas burner method is estimated less by about 2kg/m$^3$. Also, estimated water content shows difference by less than 12kg/m$^3$ in electric range method and by less than 12kg/m$^3$ in gas burner method. Therefore, it is thinked that if tested without error from preparing a sample to calculating amount of water, water content will be estimated exactly in the construction field.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.367-370
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• 2005

In this study, air meter method and capacitance measurement method to apply economically at quality control of ready-mixed concrete among various unit water content measurement technique was selected. Then, it was evaluated estimating performance of unit water content according to the change of water-binder ratio and unit water content. Also, it was examined influence about error occurrence of unit water content by change of properties of used materials. Finally, based on this study, it was proposed fundamental data to utilize measurement technique of unit water content to quality control. of ready-mixed concrete in construction field.

• 한국건축시공학회지
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• 제4권4호
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• pp.95-101
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• 2004

The purpose of this paper is to compare free-chloride content with water-soluble chloride in blast furnace cement(BSC) paste. The content of free-chloride in cement paste measured by pore solution analysis and water-soluble chloride measured by ASTM. The result of this study are as follows: 1. The concentration of chloride ion in pore solution of BSC-solidified matrix is almost as low as 43-71% compared to that of OPC-solidified matrix containing the same chloride content in cement paste. 2. The binding capacity of specimens, OPC Pl-P5, are 93.5-77%, but the binding capacity of specimens, BSC Pl-P5 are 97.1-86.1%, which is to be as high as 2-9.1% compared to OPC containing the same chloride content. 3. In terms of water-soluble chloride content in BSC paste are 15-31.7 percent of chloride addition but free-chloride content in pore solution are 2.9-13.9 percent of chloride addition. The free-chloride content in pore solution is 19.3-43.8 percent lower for the water-soluble chloride content in cement paste.

• 한국환경복원기술학회지
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• 제7권6호
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• pp.39-48
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• 2004

The purpose of this paper was to confirm the application of the equation of the soil-water characteristic curve on an unsaturated soil. To this ends, a series of suction test was conducted on the selected 4 kinds of soil which is located in Korea, using the modified pressure extractor apparatus. And it was carried out to analyze the experimental parameters which can describe the soil-water characteristics, were determined by using the data obtained from the experiment. From the results, it was found that the matric suction was varied according to the grain size distribution, amount of fine grain particle and void ratio. Also it was found that the residual volumetric water content was decreased with the void ratio, but the index related air entry value, the soil parameter related water content and the parameter with residual water content were increased with the void ratio. And the application of equation of the soil-water characteristic curve was confirmed for the various conditions and the various state by the comparison between the volumetric water content measured by the experiment and the predicted values.

• 한국안광학회지
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• 제13권4호
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• pp.59-63
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• 2008

목적: 본 연구의 목적은 수분제거 방법과 건조 방법에 따른 함수율 측정에 관하여 알아보고자 하였다. 방법: 다양한 함수율을 갖는(47%~58%) 72개의 하이드로젤 콘택트렌즈를 대상으로 중량측정법으로 함수율을 측정하였다. 실험실 온도는 $25^{\circ}C$, 습도는 21%로 유지하였다. 두 방법 모두 저온처리 후 실온에서 30분 건조하여 무게를 측정하는 방식으로 측정하였다. 결과: Dry blotting 방법은 함수율이 47.43${\pm}$8.48%로 측정되었으며, Wet blotting 방법은 48.15 ${\pm}$8.36%로 측정되었다. 또한 Wet blotting 방법으로 측정한 함수율이 약 0.7% 정도 높게 측정되었다. 건조 방법에 따른 함수율에서 vacuum oven을 사용하여 건조한 함수율이 47.89${\pm}$8.06%, microwave oven을 사용하여 건조하여 측정한 함수율이 49.56${\pm}$7.06%로 나타났으며, microwave oven을 사용하여 측정한 함수율이 약 1.67% 높은 함수율을 나타내었으나 통계적으로 유의한 차이를 나타내지는 않았다(p>0.05). 결론: 렌즈의 함수된 무게를 측정하기 위한 Dry blotting 방법과 Wet blotting 방법 중 Wet blotting에 의한 방법이 무게가 높게 측정되었으며, 함수율 역시 더 높게 측정되었다. 또한 건조된 무게를 측정하기 위해 렌즈를 건조시키는 방법에 있어 vacuum oven을 사용한 건조보다 microwave oven로 건조하여서 측정한 함수율이 더 높은 값을 나타내었으나 microwave oven을 사용할 경우 더 정확한 측정을 위해 그 microwave의 조사 강도나 시료의 위치에 있어 더욱 세심한 주의가 필요하다.

• Geomechanics and Engineering
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• 제17권3호
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• pp.271-278
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• 2019

In recent years, the crack accidents of earth and rockfill dams occur frequently. It is urgent to study the tensile strength and tensile failure mechanism of the gravelly soil in the core for the anti-crack design of the actual high earth core rockfill dam. Based on the self-developed uniaxial tensile test device, a series of uniaxial tensile test was carried out on gravelly soil with different gravel content. The compaction test shows a good linear relationship between the optimum water content and gravel content, and the relation curve of optimum water content versus maximum dry density can be fitting by two times polynomial. For the gravelly soil under its optimum water content and maximum dry density, as the gravel content increased from 0% to 50%, the tensile strength of specimens decreased from 122.6 kPa to 49.8 kPa linearly. The peak tensile strain and ultimate tensile strain all decrease with the increase of the gravel content. From the analysis of fracture energy, it is proved that the tensile capacity of gravelly soil decreases slightly with the increasing gravel content. In the case that the sample under the maximum dry density and the water content higher than the optimum water content, the comprehensive tensile capacity of the sample is the strongest. The relevant test results can provide support for the anti-crack design of the high earth core rockfill dam.

• 한국농공학회논문집
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• 제58권3호
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• pp.47-56
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• 2016

Superabsorbent Polymers (SAPs) are hydrophilic synthetic polymers which could absorb water by hundreds of their own weight. They are used for multiple purpose including hygienic goods, soil conditioners, and hospital supplies. It is necessary to investigate the standard of their use including the amendment rate for soil application in agricultural fields. It is also important to understand their effects on the soil water content and engineering characteristics. The objective of this study is to find the water absorbing capacity and reusability of SAPs, and the characteristics of water release and effect of them on soil water content and engineering characteristics. In the result, SAPs per unit weight (1 g) used for this research could absorb about 200 g of water in max. The water absorbing capacity decreased after SAPs were used repeatedly. Released water of SAPs could provide the soils with about 9 % of the soil water content. Soil water content increased with decreasing distance from the SAPs. The distance of release was spreaded out with increasing water absorbed of SAPs. Finally, when a drainage and the capacity of soil water content were considered, it is recommended to amend the SAPs with soil by less than 0.25 %.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 연약지반처리위원회 학술세미나
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• pp.84-95
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• 1999

Laboratory experiments were performed to evaluate the strength characteristics of solidified sandy soils by portland cement with mixing conditions. Factors considered in the experiments were the fine content(<#200, %), cement content(%) and water-cement ratio and unconfined compressive strength tests were performed on samples at 7 and 28 cured day. Results of tests showed that for a low cement content(7%∼10%) the fine content was very important while for a high cement content the water-cement ratio was very important. For 7%∼10% cement content, the optimum fine content which gained maximum strength was about 30%. But for 13% cement content, low fine content and water-cement ratio were more useful than others. In the multi regression analysis, significant equation was gained.