• Geomechanics and Engineering
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• v.30 no.2
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• pp.201-210
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• 2022

This paper presents a study regarding the influence of various water levels on the characteristics of subgrade mud pumping through a self-developed test instrument. The characteristics of mud pumping are primarily reflected by axial strain, excess pore water pressure, and fine particle migration. The results show that the axial strain increases nonlinearly with an increase in cycles number; however, the increasing rate gradually decreases, thus, an empirical model for calculating the axial strain of the samples is presented. The excess pore water pressure increases rapidly first and then decreases slowly with an increase in cycles number. Furthermore, the dynamic stress within the soil first rapidly decreases and then eventually slows. The results indicate that the axial strain, excess pore water pressure, and the height and weight of the migrated fine particles decrease significantly with a low water level. In this study, when the water level is 50 mm lower than the subgrade soil surface, the issue of subgrade mud pumping no longer exist.

• Geomechanics and Engineering
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• v.20 no.3
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• pp.267-273
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• 2020

Solutions of the water pressure and groundwater inflow distribution along the tunnel perimeter in a half-infinite aquifer were investigated considering the conditions of the constant head and constant water pressure. It is assumed that the circular tunnel is buried in a fully saturated, homogeneous, isotropic and half-infinite space. Coordinate transformation technique was adopted, the problem of solving the control equations of water pressure in the Cartesian coordinate was transformed to that in the bipolar coordinate system, which can significantly simplify the derivation procedure of the water pressure and inflow distribution. The validation results show the accuracy and advantage of the proposed approach.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.370-378
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• 2003

Continuous seismic refraction, reflection and echo-sounder surveys conducted at Koyna Project site provided geotechnical information which helped in choosing the alignment for Head race tunnel and in designing and choosing the site for Lake Tap. Seismic refraction survey both on land and in shallow water determined depths to bedrock and helped in inferring the bedrock quality. Seismic reflection survey mapped the subsurface stratigraphy with high resolution. Reservoir-bed and bedrock contours drawn from the results of the survey helped in choosing the tunnel alignment and the lake tap position cost effectively. It was inferred from the results of the survey that the geology and the quality of rock do not change unexpectedly around the site for extension of Head race tunnel and the lake tapping. The bedrock levels evaluated by seismic survey agreed remarkably well with those inferred in boreholes having Rock Quality Designation 90 percent or more.

• Geomechanics and Engineering
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• v.16 no.1
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• pp.85-95
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• 2018

Water affects the mechanical properties of coal and stress wave propagation. To comprehensively investigate the effect of water content on the properties of coal, laboratory tests including X-Ray Diffraction (XRD) analysis, P-wave test, S-wave test, static and dynamic compression test with different water contents were conducted. The compressive strength, elastic modulus and failure strain and their mechanism of coal specimen under coupled static-dynamic load with the increased water content were observed. Meanwhile, energy transmission and dissipation characteristics of a stress wave in coal specimens with different water contents under dynamic load and its relation with the failure features, such as fragmentation and fractal dimension, of coal was analyzed. Furthermore, the dynamic interpretation of water infusion to prevent coal burst based on water infusion model of coal seam roadway was provided.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.600-601
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• 2005

• Journal of the Korean Society of Tobacco Science
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• v.29 no.2
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• pp.59-65
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• 2007

The study was carried out to investigate water activity, physicochemical properties and color degree of burley tobacco stored in shelf with different moisture content for 56 days. The study was consist of two experimental designs, that is, moisture content in burley tobacco was kept to 13 to 15 %, 17 to 19 %, and 21 to 23 % under ambient temperature of $20^{\circ}C$ with relative humidity of 24 %, and another group of in burley tobacco was only kept in ambient temperature of $3^{\circ}C$ with relative humidity of 50 % for 56 days with same water content of former treatment. Normal leaves were kept for 56 days under 21 to 23% of moisture content with increased water activity and TSNA(tobacco-specific nitrosamine content. It was considered that favorable leaves conditions are due to favorable microbial growth resulting in increased TSNA content. The total nitrogen content has not changed in two experimental groups for 56 days, otherwise the nitrate form nitrogen and total alkaloid contents were only increased by 21 to 23 % of water content. Degree of pH change was slightly decreased in both storage and water treatment. It was more decreased in 21 to 23% of moisture content than that of other moisture content. In stored leaf tobacco, higher moisture content caused lower brightness, yellow degree, and carbonization quotient.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.13 no.4
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• pp.8-13
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• 2017

The effects of operational conditions of cooling water system on energy consumption for central cooling system are researched by using TRNSYS program. Cooling tower water pump flow rate, cooling tower fan flow rate, and condenser water temperature with various dry-bulb and wet-bulb temperatures are varied and their effects on total and component power consumption are studied. If the fan maximum flow rates of cooling tower is decreased, cooling tower fan and total power consumptions are increased. If the cooling tower water pump maximum flow rates is decreased, chiller and total power consumptions are increased. If condenser water set-point temperature is increased, chiller power consumption is increased and cooling tower fan power consumption is decreased, respectively.

• The Journal of the Korea Contents Association
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• v.17 no.10
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• pp.538-547
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• 2017

Korea's water management system is typically a multi-ministerial system, so its efficiency is declining. In order to propose current state and improvement plan of the water management in Korea, this study discussed the improvement of central and local water management. The water management problems are lack of water policy coordination system, conflicts between ministries due to function of water quantity, water quality and agricultural water, redundant investment and inefficiency, insufficient recognition of water autonomy, concentrated central management and deepening regional disparities, lack of financial resources, etc. Hence, improvement to solve the problem includes strengthening the coordination of water management functions between ministries, transferring water management functions of central ministries and strengthening local capacity, and desirable role allocation of central and local governments. In addition, improvement at the local include efforts to change awareness of the water detailed and get water autonomy, integrate management of the watershed, strengthen the local community, secure financial resources, etc.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.200-200
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• 2016

Climate changes have impacted to many sectors including water resources in Vietnam. Vietnam is agricultural development country having a lot of reservoirs. These reservoirs play a very important role in flow regulation for water supply to economic sectors. In the context of undesirable impacts of climate change such as increasing temparature, evaporation, changing rainfall and rainfall pattern, water demands and inflow to reservoirs also are being influenced. This leads to changes of resevoir exploitation effects that needs to be assessed for adaptation solutions. This arcticle summaries the development of a tool for quick assessement of climate change impacts on exploitation effect of reservoir in central provinces of Vietnam.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.314-314
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• 2022

In the production of rice flour, wet milling is a method of milling rice after soaking it in water, and it takes a lot of time and cost from milling to drying. To overcome this problem, the floury type rice was developed for dry milling and it is known to have round starch granules, low content of damaged starch after milling, and a starch structure similar to wheat. Because of its unique properties different from normal rice, it is necessary to research on processing and characteristics of floury-type rice to expand its utility in the food industry. Therefore, this study aimed to prepare the pregelatinized floury type rice (Baromi2) by autoclave and investigate their physicochemical properties. As the heat treatment time increased, the brightness decreased from 83.8 to 76.8, however, both redness and yellowness increased from 0.57 to 4.5 and from 14.58 to 21.13, respectively. Despite of same treatment time, soaking in water (10 min) before autoclaving increased the solubility and swelling power of Baromi2 over 2 times. The peak viscosity of native Baromi2 was over 2000 RVU, on the other hand, there was a significantly decrease to less than 1000 RVU of pregelatinized Baromi2. Heat treatment without immersion caused partial gelatinization of starch, resulting that some starch granules maintaining their integrity. Whereas there were no starch granules in heat treatment with soaking in water due to complete gelatinization. This study would be helpful to the suggestion of using heat-treated floury-type rice as an intermediate material in the food industry in the future.