• Structural Engineering and Mechanics
• /
• v.91 no.5
• /
• pp.469-486
• /
• 2024

Electric transformers are major components of electrical systems, and damage to them caused by earthquakes can result in significant financial loss. The current study modeled a three-dimensional (3D) isolated electrical transformer under horizontal and vertical records from different earthquakes. Instead of using fixed coefficients, an improved wavelet method has been used to create the greatest compatibility between the response spectra and the target spectrum. This method has primarily been used for dynamic analysis of isolated structures with spring-damper devices because it has shown greater accuracy in predicting the response of such structures. The effect of the nonlinear soil-structure interaction on the probability of transformer failure also has been investigated. Soil and structure interaction modeling was carried out using a beam on a nonlinear Winkler foundation. The effect of the nonlinear soil-structure interaction during dynamic analysis of transformers revealed that the greatest increase in the probability of transformer failure was in the fixed-base condition when the structure was located on soft soil. This intensified the response of the structure and increased the probability of transformer failure by up to 27% for far-field and up to 95% for near-field ground motions. A comparison of the results indicates that the use of 3D isolation systems in transformers in areas with soft clay that are subject to near-field ground motions can strongly reduce the probability of failure and improve the seismic performance of the transformer.

• Agricultural and Biosystems Engineering
• /
• v.4 no.2
• /
• pp.45-49
• /
• 2003

Achievements in the real-time soil spectro-photometer are: an improved soil penetrator to ensure a uniform soil surface under high speed conditions, real-time collecting of underground soil reflectance, getting underground soil color images, use of a RTK-GPS, and all units are arranged for compactness. With the soil spectrophotometer, field experiments were conducted in a 0.5 ha paddy field. With the original reflectance, averaging and multiple scatter correction, Kubelka-Munk (KM) transformation as soil absorption, its 1st and 2nd derivatives were calculated. When the spectra was highly correlated with the soil parameters, stepwise regression analysis was conducted. Results include the best prediction models for moisture, soil organic matter (SOM), nitrate nitrogen ($NO_3-N$), pH and electric conductivity (EC), and soil maps obtained by block kriging analysis.

• Journal of Industrial Technology
• /
• v.25 no.A
• /
• pp.67-73
• /
• 2005

In this research, centrifuge model experiments and numerical approach of finite element method to analyze experimental results were performed to investigate the behavior of improved ground with sand compaction piles. One of typical clay minerals, kaolinite powder, were prepared for soft ground in model tests. Jumunjin standard sand was used to sand compaction pile installed in the soft soil. In order to investigate the characteristics of mechanical behavior of sand compaction piles with low replacement ratios, centrifuge model experiments with the replacement ratio of 40%, changing the width of improved area with respect to testing results the width of surcharge loads, were carried out to obtain of bearing capacity, characteristics of load-settlement, vertical stresses acting on the sand pile and the soft soil failure mechanism in improved ground.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.2 no.2
• /
• pp.158-165
• /
• 2014

The enormous quantity of 'Bayer-Process by-products' (BP by-products) discharged by industries producing alumina from bauxite represents an environmental and economical problem. As it is mainly composed of $Fe_2O_3$, $Al_2O_3$, $SiO_2$, CaO and $Na_2O$, it is thought that using BP by-products as a construction material is an effective way to consume such a large quantity of alkaline waste. In this study, This study evaluates the effect of alkali-activated binder based on recycling BP by-products on soil improvement through the evaluation of slope stability and seepage flow numerical analysis. The results of analysis of ground slope safety at dry season and wet season meet standard (Ministry of Land, Infrastructure and Transport, 2006) Especially, when wet season, the ground used soil improving material meet standard, while the ground used soil-nailing method doesn't. Also, permeability coefficient of improved soil is smaller than that of natural soil and saturation depth of reinforced ground surface with improve soil is lower than that of natural soil.

• Journal of Soil and Groundwater Environment
• /
• v.22 no.6
• /
• pp.22-28
• /
• 2017

The accuracy of analytical results in response to the use of different additives ($NH_4Cl$, KCl, $LaCl_3$) and oxidant gases was evaluated and compared by using Atomic Absorption Spectrometry (AAS). Identification of spectroscopic interferences and possible improvements in Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) analysis were also discussed. The average accuracies of total chromium using Certified Reference Materials (CRMs) were found to be 72.1~94.2% in air/acetylene flame condition by AAS, and they were improved to 100.5~110.5% when the oxidants was changed to nitrous oxide rather than adding the additives. The field samples showed similar trends to CRMs, but chromium concentrations were highly variable depending on analytical conditions. The average accuracies using CRMs were estimated to be 89.3~166.1% by ICP-AES, and improved to below 121.7% after eliminating iron interference. Field samples with low chromium and high iron concentration were measured to be > 30% lower in total chromium concentrations by ICP-AES than AAS in nitrous oxide/acetylene flame. Total chromium concentrations in soil could be analyzed with better accuracy under nitrous oxide/acetylene flame by AAS because it was more effective to increase the temperature of the flame than to eliminate the chemical interference for maximizing atomization of chromium. When using ICP-AES, interference substances, total chromium levels, and analytical conditions should be also considered.

• Structural Monitoring and Maintenance
• /
• v.11 no.3
• /
• pp.187-202
• /
• 2024

For the problems of high compressibility and low strength of peat soil formed by lake-phase deposition in Dianchi Lake, microbial-induced calcium carbonate deposition (MICP), phyto-urease-induced calcium carbonate deposition (EICP) and phyto-urease-induced calcium carbonate deposition combined with lignin (EICP combined with lignin) were used to reinforce the peat soil, the changes in mechanical properties of the soil before and after the reinforcement of the peat soil were experimentally investigated, and the effect and mechanism of peat soil reinforcing by the three reinforcing techniques were tested and analyzed using X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that: compared to the unreinforced remolded peat soil specimens, the unconfined compressive strength (UCS), cohesion and internal friction angle of the specimens reinforced by MICP, EICP and EICP combined with lignin techniques have been greatly improved, and the permeability resistance has been improved by two, two and three orders of magnitude, respectively; the different methods of reinforcing generate different calcium carbonate crystalline phases, with the EICP combined with lignin technique generating the most stable calcite, and the MICP and EICP techniques generating a mixed phase of calcite and spherulitic chalcocite. Analyses showed that for peat soil reinforcement, the acidic environment of peat soil inhibited the growth and reproduction of bacteria, EICP technology was superior to MICP technology, and the addition of lignin solved the defect of the EICP technology that did not have a "nucleation site", so EICP combined with lignin reinforcement was preferred for the improvement of peat soil.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.09a
• /
• pp.302-305
• /
• 2003

The electrokinetic remediation tests for natural soil contaminated by lead are performed on unsaturated conditions, in which the degree of saturation is controlled through the changes in water content and the constant unit weight. At the degree of saturation of 70% the small acid range and electrical potential is developed. The changes in the water content are little above the saturation of 90%. But it is increased by 1.7 times at the degree of saturation of 70%. Finally, the efficiency of extraction is improved at 70% than 100%.

• Textile Coloration and Finishing
• /
• v.26 no.3
• /
• pp.209-217
• /
• 2014

Detergency and soil redeposition of wool fabric in drycleaning solvents, i.e. petroleum solvent, perchloroethylene (PCE), decamethylcyclopentasiloxane($D_5$), with commercial detergents were studied. The detergency of wool soiled cloth in drycleaning solvents without detergents were the order of PCE > petroleum solvent > $D_5$. When commercial detergents were added to the system, the detergency were greatly improved. When 1.0% water was added to solvents/commercial detergents system, the detergency of petroleum solvent and PCE improved whereas that of $D_5$ decreased. The soil redeposition prevention effects of solvents were the same order of detergency, i.e. PCE > petroleum solvent > $D_5$. When commercial detergents were added to the system, the soil redeposition changed depending on solvents and detergents. The soil redeposition in $D_5$ became higher with a commercial detergent, therefore it is important to develop appropriate detergents for $D_5$. Three silicone surfactants were tested for detergency and soil redeposition in $D_5$ to find candidate surfactants for drycleaning detergent formulations. Silicone surfactant PEG/PPG-19/19 Dimethicone was found to be the best surfactant for $D_5$ drycleaning detergents.

• Textile Coloration and Finishing
• /
• v.24 no.2
• /
• pp.138-144
• /
• 2012

Detergency and soil redeposition of wool fabric in 8 nonionic surfactants (Span 20, 40, 60, 80/Tween 20, 40, 60, 80) and 4 solvents (water, petroleum, perchloroethylene(PCE), decamethylcyclopentasiloxane($D_5$)) were studied. Detergency of wool fabric in water was very low with and without surfactants due to the low wetting and difficulty in penetration of water into the fabric. Lipophilic surfactants improved the detergency of wool fabric in petroleum solvent and PCE. The detergency of wool fabric in $D_5$ was similar to that in petroleum solvent without surfactants. When water was solubilized, Span 20 addition to petroleum solvent and PCE increased the detergency of wool fabric. The detergency for $D_5$ was improved with solubilized water, however, it was lowered when the surfactants were added to the system. Therefore, it is important to formulate appropriate detergents which have good solubility and affinity to silicone for $D_5$ charge system. Hydrophilic surfactants were effective for water and lipophilic surfactants were effective for petroleum solvent and PCE in soil redeposition prevention of wool fabric. The soil redeposition prevention effects are not found in $D_5$ with both Span 20 and Tween 20. The same tendency of results in soil redeposition of wool fabric is observed when water is solubilized.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.10 no.2
• /
• pp.34-43
• /
• 2007

To investigate the restoration procedure on soil physical properties and vegetation at the surface of strip road affected by timber harvesting operation. This study was carried out at strip roads constructed between 1989 and 1994 in Mt. Baekun, Kwangyang, Chollanam-Do. Soil hardness of the surface layer was improved with change of time after strip road construction, but that of 7.6~15 cm depth from the surface was not improved. According to linear regression analysis, it was estimated 16.6 years in 0~7.5 cm and 16.9 years in 7.6~15 cm soil depth to be restored to natural forest lands. The amount of surface soil erosion was 0.045$m^3$/km/yr on strip roads constructed in 1989 and 1990, and road constructed in 1994 showed the highest value (4.5$m^3$/km/yr). Vegetation coverage rates of road surface were 96.7% in strip roads constructed in 1990. Those of cutslope and fillslope were highest in roads constructed in 1990. The results indicated that strip roads were restored with change of time after road construction.