• 한국물환경학회지
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• 제22권1호
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• pp.97-103
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• 2006

Excess sludge treatment and disposal currently represent a rising challenge for domestic or wastewater treatment plants due to economic, environmental and regulation factors. Conventional gravity sedimentation process has been widely used in sludge thickening. The operation method of the process is very simple, but the process requires long detention time for sludge thickening, uses polymers, and shows low sludge thickening efficiency. To solve the problems, we studied on DAF (Dissolved Air Flotation) system. We use bulking sludge of a paper manufacturing plant. The effects of parameters such as SVI (Sludge Volume Index), storage time, initial concentration and wet density of excess sludge were examined. The results showed that the more SVI was low, the more sludge was thickened. As storage time goes by, SVI was increased and thickening performance was deteriorated. In order to improve flotation performance at high concentration, high recycling ratio and pressure did not increase the concentration due to thickening limitation. The addition of 0.8 g/L of loess was increased flotation efficiency of 1.41 times.

• 상하수도학회지
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• 제8권2호
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• pp.25-34
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• 1994

In this research, investigations were made on the effect of type and load of organic substrate on phosphorus release. Reactors of three different sizes were operated, being fed on five kinds of organic substrates. The quantitative analyses were made on phosphorus release and substrate utilization under anaerobic condition. The molar ratios of the uptaken organic substrate to the released phosphorus were 0.5 with acetate, 0.6 with glucose, 0.8 with glucose/acetate, and 1.2 with glucose/acids, respectively. The phosphorus release was inhibited at the higher organic load than the normal at stead state. Both acetate and acids/glucose enhanced phosphorus release- as well as uptake-rate, however, the complete phosphorus removal was achieved after the microbial adaptation to the new environment. In case with acetate, operation was hampered by the poor sludge settleability and phosphorus uptake was not enough although the phosphorus release was active. But with milk/starch, the phosphorus release and uptake was well developed even though phosphorus release was not comparatively high. From this study, it was concluded that organic substrates, such as glucose seemed to be converted fatty acids after fast bio-sorption, followed by concurrent uptake of these acids by excess phosphorus removing bacteria.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.412-415
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• 2017

본 연구에서는 금속을 담지한 alumina bead 촉매를 이용하여 ammonium dinitramide (ADN)기반 단일액상추진제 분해 성능 분석을 수행하였다. Alumina bead를 $1200^{\circ}C$에서 소성한 후, 회전 증발기를 이용하여 과량 용액 함침법 (Excess water impregnation)으로 alumina bead에 Pt 및 Cu 를 담지하였다. 자체 제작한 batch 반응기에서 ADN기반 단일액상추진제 분해 온도($T_{dec}$)를 측정하였다. Cu/$Al_2O_3$ 촉매가 Pt/$Al_2O_3$ 촉매에 비해 분해 온도가 더 낮게 나타났으며, $T_{dec}$ 는 약 $130^{\circ}C$이었다.

• 한국약용작물학회지
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• 제19권4호
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• pp.246-250
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• 2011

This study was carried out to investigate the characteristics of Rhizome rot incidence of Platycodon grandiflorus by cultivation period and ridge width and furrow depth. The three types of ridge width 0.8, 1.0, and 1.2 m and several levels of furrow depth and 6 levels cultivation period. This experiment was done in farmer's farm and the treatments were also classified in the same spot. In this investigation, ridge width, soil water content, soil hardness, and cultivation period were positively related with Rhizome rot incidence, however, furrow depth was negatively related with that. So this experiment could draw a conclusion : excess water damage and soil hardness could directly or indirectly effect on the Rhizome rot incidence, so cultivation method should be developed such as making underground ditch or cultivation in well draining soil for escaping excess waster damage.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 1997년도 학술발표회 논문집
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• pp.192-198
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• 1997

포화도의 공간적 변화인 지형지수를 계산하기 위한 다중흐름 알고리듬이 지형정보시스템인 GRASS와 연계되어 개발되었다. 본 연구는 소규모 농경지 배수구역에 대하여 적용하였다. 지하수위에 대한 타일 시스템의 영향이 DEM모형과 Laplace식에 의해서 효과적으로 고려될 수 있었다. 본 연구결과, 타일시스템을 고려한 유역은 타일시스템을 고려하지 않는 경우와 비교하여 높은 포화도를 가지고 있는 것으로 나타났으며, 예측된 riparian 유역은 실제의 유역조건과 잘 일치되고 있다. 본 연구에서는 지형지수를 산정함에 있어 타일 시스템의 효과를 고려해야 함을 제안하였다.

• Geomechanics and Engineering
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• 제29권5호
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• pp.497-508
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• 2022

Tailings fluidization (i.e., tailings behave as being fluidized) under cyclic loading is one concern during the construction of tailings dams, especially in the shallow tailings layers. The primary goal of this study is to evaluate the responses of tailings under cyclic loadings and the tailings potential for fluidization. A series of cyclic triaxial undrained and drained tests were performed on medium and dense tailings samples under various cyclic stress ratios (CSR). The results indicated that axial strain and excess pore water pressure accumulated over time due to cyclic loading. However, the accumulations were dependent on CSR values, densities, and drainage conditions. The fluidization potential analysis in this study was then evaluated based on the obtained cyclic axial strain and excess pore water pressure. As a result, tailings samples were stable (unfluidized) under small CSR values, and the critical CSR values, where the tailings fluidized, varied depending on the density of tailings samples. Tailings fluidization is triggered as cyclic stress ratios reach critical values. In this study, the critical CSR values were found to be 0.15 and 0.40 for medium and dense samples, respectively.

• Geomechanics and Engineering
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• 제37권4호
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• pp.359-370
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• 2024

The primary goal of this study is to evaluate the migration of fine granular materials into overlying layers under cyclic loading using a modified large-scale triaxial system as a physical model test. Samples prepared for the modified large-scale triaxial system comprised a 60 mm thick gravel layer overlying a 120 mm thick subgrade layer, which could be either tailings or railway sand. A quantitative analysis of the migration of fine granular materials was based on the mass percentage and grain size of migrated materials collected in the gravel. In addition, the cyclic characteristics, i.e., accumulated axial strain and excess pore water pressure, were evaluated. As a result, the total migration rate of the railway sand sample was found to be small. However, the total migration rate of the sample containing tailings in the subgrade layer was much higher than that of the railway sand sample. In addition, the migration analysis revealed that finer tailings particles tended to be migrated into the upper gravel layer easier than coarser tailings particles under cyclic loading. This could be involved in significant increases in excess pore water pressure at the last cycles of the physical model test.

• 대한한의학원전학회지
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• 제20권3호
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• pp.49-56
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• 2007

The "Somun Jogyongron(素問 調經論)" describes excess and deficiency syndromes. The study suggests that excess syndrome(實證) is caused by vigorous pathogenic fire(火邪)(the spirit(神)), pathogenic dryness(燥邪)(Gi(氣)), pathogenic wind(風邪)(blood(血)), pathogenic dampness(濕邪)(physique(形)) or pathogenic coldness(寒邪)(will(志)). When pathogenic fire is dominant within the body, Gi and blood becomes excessive and come out of the body, but the body cannot take them back, leading to the symptom in which the patient cannot stop laughing. When pathogenic dryness prevails, the lung(肺) cannot function properly. This means that the convergence(收斂) function of the clearing the lung and descending Gi(肅降) is deteriorated, and the patient shows symptoms of dyspnea and cough. Strong pathogenic wind increases the ascencling Gi in the liver(肝氣) and fuel angry emotion when the patient becomes upset. When pathogenic dampness is dominant, spleen(脾) function drops due to lumping effects, and the patient will experience abdominal distention(腹脹), which will disturb urination and defecation. When pathogenic coldness prevails, abdominal distention occurs due to condensating effects, and Yang Gj(陽氣) in the kidney(腎) is disturbed, leading to digestion disorders and eventually water-grain dysentery. Deficiency syndrome is caused by the lack of essential Gi(精氣) in the five viscera(五藏). Deficiency of sprit means the lack of Gi in the heart(心氣), so the patient becomes vulnerable to sadness. Deficiency of Gi means the lack of Gi in the lung(肺氣), so the patient may have breathing disorders. Deficiency of blood means the lack of Gi in the Liver(肝氣), so the patient can be easily scared. Deficiency of physique means the lack of Gi in the spleen(脾氣), making it difficult to use arms and legs. Deficiency of will means the lack of Gi in the kidney(腎氣), so Gowl syndrome(厥證) can ensue.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.365-372
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• 1999

The plane deformation and spatial seepage(PDSS) analysis was developed to consider 3D flow of excess pore water as well as plane deformation of ground. Here is newly developed an equivalent model for PDSS analysis, which was the purpose to reduce number of finite elements and to take the effects of smear and well resistance into consideration. As the result of PDSS analysis with applying the new model, it is showed that the settlement-tin e relationship by PDSS agrees well with those of Plane strain(PS) and axisymmetric analyses, irrespective of existence of untreated layer. And the excess pore pressure distribution by PDSS is relatively agreed with that of axisymmetric analysis, not with that of PS.

• 아시안잔디학회지
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• 제8권1호
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• pp.29-36
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• 1994

We studied on the mineral nutrients and productivity of grasslands in Kimhwa. The vascular flora of grasslands in Sakok-ri, Wasoo-ri, and Yukdan-ri located at Kimhwa were composed of 39, 28, and 32 species respectively. The most important species were Arundinella hirta and Miscanthus sinensis These two species contributed greatly to the standing crops of live material which was in excess of $146.47g/m^2$ throughout the growing season. The daily production throughout the growing season was in excess of $1.04 g/m^2$. Factors which affected the daily productivity of grasslands in Kimhwa were phosphours and water content.