• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.3C
• /
• pp.93-102
• /
• 2011

Most experimental studies on soil liquefaction are related to clean sands. However, soils in the field or reclaimed grounds commonly contain some amounts of silt and clay rather than clean sand only. Many researchers investigated the effect of fine contents on liquefaction resistance and mainly used non-plastic fines such as silts. In this study, 10% of plastic fines with various plasticity index (PI) such as 8, 18, 50, and 377 were mixed with wet Nakdong River sand and then loose, medium, and dense specimens were prepared by undercompaction method. A series of undrained cyclic triaxial tests were carried out by applying three different cyclic stress ratios. As a result, the liquefaction resistance tended to decrease as a PI of fines in the specimens with equal fine content increased. On the other hand, the difference between loose specimens with low and high plasticity fines was not clearly observed in terms of liquefaction resistance. However, in the case of dense specimens, liquefaction resistance decreased up to 40% as a plasticity of fines increased.

• Journal of Conservation Science
• /
• v.34 no.2
• /
• pp.107-118
• /
• 2018

This report does studied for making the method of conserving bracket murals in Daeungjeon of Jikjisa Temple, through the scientific way. Results of evaluated the conservation status at the braket mural paintings, most serious damage is structural damage like cracks, breakage, and delamination. After optical investigation, a characteristic point wasn't found such as underdrawing or traces of a coat of paint. The ultrasonic examination speed by each wall painting was measured from about 195.8 m/s to 392.7 m/s, according to the location of the surface, and it was able to compare the surface properties according to the location. In Infrared-thermal image measurement shows that wall layer separation and paint layer delamination are closely detected, therefore it was able to judge of damage on the objective way. Material analysis revealed that the walls were made by sand and weathering soil. The wall layer combined sand with less than fine sand size by nearly 5:5, and the finishing layer was found to have mixed medium sand and fine sand at approximately 6:4 rates. However, In case of finishing layer, mixing ratios of sizes less than very fine sand were found to be significantly lower than wall. Therefore, it is estimated that the plysical damage such as the separation between the layers of the walls created in the braket mural paintings, is continuously caused by changes in the internal stresses and volume ratio caused by the density differences between the wall and the finishing layers.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.15 no.1
• /
• pp.64-75
• /
• 2012

To predict the future distribution of forest vegetation, the present forest stand distributions of South Korea were represented by multinomial logit model with the following environmental variables: summer average precipitation, the coldest month average temperature, elevation, degree of base saturation, and soil organic matter. The future forest community was predicted by applying the MIROC3.2 hires A1B scenario. The future climate data were downscaled by statistically method. The coldest month average temperature increased $4.4^{\circ}C$, $6.0^{\circ}C$, and $9.4^{\circ}C$, and 3 months average precipitation changed -1.2%, 5.7%, and 5.3% for 2020s, 2050s, and 2080s respectively. For the projected summer precipitation and the coldest temperature, the future deciduous and mixed forests in the study area increased 56.9% and 8.3% and the coniferous forest decreased 11.2% in 2080s based on present.

• Journal of the Korea Concrete Institute
• /
• v.14 no.3
• /
• pp.420-429
• /
• 2002

The amount of $CO_2$-silicate bonded waste foundry sand(WFS) occurred in Korea is over 800,000 ton per year. WFS, as a by-product, is generated through manufacturing process of foundry may affect our environmental contamination, The reason is that WFS has been buried itself not less than 90％ out of total WFS. So, it can give damage on the ground of contamination in soil and underwater. Therefore, it is necessary to establish the method recycling WFS because of being intensified waste management law. In this study, we performed the research with respect to harmful component analysis, the qualities of WFS mortar and concrete mixed with WFS. As the results the specific gravity of WFS is the same as that of natural aggregate while unit weight and percentage of solids of WFS are smaller than those of it. But it is found that WFS can be used by substituting WFS for natural aggregate after control of poor grade of WFS. The flowability of mortar and concrete with WFS is inferior to those of natural aggregate, and the setting time of concrete with WFS is faster than that with only natural aggregate, On the contrary, the bleeding of concrete with WFS is shown good result, and compressive and tensile strength of concrete substituted WFS for 30％ are higher than those with only natural aggregate regardless of elapsed time.

• Journal of Plant Biotechnology
• /
• v.46 no.2
• /
• pp.119-126
• /
• 2019

This study was conducted to investigate the optimal culture method for gametophyte and sporophyte propagation in Coniogramme japonica (Thunb.) Diels, which can be used in various fields. The propagation of prothallus were cultured in 1/4 - 1 Murashige and Skoog medium and Knop medium for 10 weeks. The results indicated that the fresh weight of prothallus was the highest (14.5 g) in 1MS medium. Subsequently, various concentrations of sucrose, activated charcoal and nitrogen source were also added to 1MS medium and cultured for 8 weeks. The results provided that the sucrose concentration was 3% and the fresh weight of prothallus was the highest 10.8 g. According to the concentration in the range of 8.8 ~ 10.8 g, in the case of activated charcoal, the four treatments showed no significant difference. The nitrogen source was added at a concentration of 30, 60 and 120 mM with the ratio of ${NH_4}^+:{NO_3}^-$ being 1 : 2. As a result, the fresh weight of all treatments increased to similar level but there was no significant difference. We investigated sporophyte formation according to soil type and the highest number of sporophytes at 228.0 was formed in soils mixed with horticultural substrate and decomposed granite at 2 : 1 (v : v). On the other hand, sporophyte was not formed in soils containing peatmoss except for the one with peatmoss and decomposed granite at 2 : 1 (v : v).

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.27 no.1
• /
• pp.78-83
• /
• 1982

Seedling blight of sesame (Sesamum indicum L.) is one of the most serious diseases in Korea. This study was performed to control seedling blight in the field where sesame has been cultured for 4 years of Industrial Crop Division at the Crop Experiment Station. The pathogenic fungi of seedling blight which is known Fusarium oxysporum f. vasinfectium and Rhizoctonia solani was inoculated to the wheat media and it was spreaded on the experimental field in the concentration of 109 of wheat media mixed with 10g of fine soil. Seed sterilization was the most effective method for seedling blight control for two year experiment. Seed sterilant Benlate-T was highly effective for con trolling seedling blight with infection rate of 4% and yield of 40.7kg per 10a comparing to the control with infection rate of 96% and grain yield of 6.4kg per l0a, the other chemicals, Busan 30, Vitathiram, Captan showed good effect to control seedling blight, but less effect to the Benlate-T. The spraying treatments on leaf surface 25 days after sowing were not effective to seedling blight.

• Analytical Science and Technology
• /
• v.22 no.1
• /
• pp.51-56
• /
• 2009

The samples from coastal sand dune stratum in Chollipo were dated by Optically Stimulated Luminescence (OSL) with modified Single Aliquots Regeneration (SAR) method. It is possible to choose the OSL signals by thermal treatments such as preheat and cut-heat in SAR procedure. Preheat and cut-heat of $260^{\circ}C$ for 10 sec $-220^{\circ}C$ for 0 sec, and $270^{\circ}C$ for 10 sec $-270^{\circ}C$ for 10 sec were applied for estimation of equivalent dose of the samples. The OSL signals from different thermal treatment were used for OSL dating. Equivalent dose were estimated with 4 fractionated grain distributions with $75{\mu}m$, $150{\mu}m$ and $200{\mu}m$ sieves with above heating treatments. Consequently, the estimated dose were differently valued in sample sizes and applied heating treatments, different stratum ages were calculated. The ages from radiocarbon dating were compared with the OSL ages. The ages varying with grain sizes produce that the site sampled were formed with mixed soil sources.

• Journal of the Korean Applied Science and Technology
• /
• v.39 no.2
• /
• pp.368-376
• /
• 2022

Spontaneous ignition occurs in industrial sites or anywhere in our lives, and is a phenomenon in which a substance ignites itself without an ignition source in the atmosphere. As the rate of chemical reaction increases, the heat generated increases, and the risk of spontaneous ignition increases. In this study, safe raw materials used for food and cosmetics were mixed to prepare coal spontaneous ignition prevention agents specifically among various spontaneous ignition phenomena. The effect of suppressing spontaneous combustion of coal was confirmed through lab and field tests with low-calorie, low-grade coal from Indonesia. As a result of the outdoor field test, the ignition prevention agent manufactured in this study compared with the control group(Fire after 90 days) showed excellent ignition inhibitors for more than 120 days. In addition, CO concentration control was confirmed by comparing the concentration of carbon monoxide for 50 days at the indoor coal yard. It was confirmed that the results were better than the comparative group coal and the existing anti-firing method. In addition, the possibility of coal fire prevention agents for indoor coal farms will be applied from 2024 was confirmed by studying the environment and safety of workers' working environments through official test such as soil and water quality test, MSDS of coal fire prevention agents in consideration of working workers, water quality, and eye irritation tests.

• Journal of the Korean Society of Groundwater Environment
• /
• v.7 no.1
• /
• pp.32-46
• /
• 2000

Hydrogeochemical and isotope ($\delta$$^{18}$ O, $\delta$D, $^3$H, $\delta$$^{13}$ C, $\delta$$^{34}$ S, $^{87}$ Sr/$^{86}$ Sr) studies of various kinds of waters (thermal groundwater, deep groundwater, shallow groundwater, and surface water) from the Yusung area were carried out in order to elucidate their geochemical characteristics such as distribution and behaviour of major/minor elements, geochemical evolution, reservoir temperature, and water-rock interaction of the thermal groundwater. Thermal groundwater of the Yusung area is formed by heating at depth during deep circlulation of groundwater and is evolved into Na-HCO$_3$type water by hydrolysis of silicate minerals with calcite precipitation and mixing of shallow groundwater. High NO$_3$contents of many thermal and deep groundwater samples indicate that the thermal or deep groundwaters were mixed with contaminated shallow groundwater and/or surface water. $\delta$$^{18}$ O and $\delta$D are plotted around the global meteoric water line and there are no differences between the various types of water. Tritium contents of shallow groundwater, deep groundwater and thermal groundwater are quite different, but show that the thermal groundwater was mixed with surface water and/or shallow groundwater during uprising to surface after being heated at depths. $\delta$$^{13}$ C values of all water samples are very low (average -16.3$\textperthousand$%o). Such low $\delta$$^{13}$ C values indicate that the source of carbon is organic material and all waters from the Yusung area were affected by $CO_2$ gas originated from near surface environment. $\delta$$^{34}$ S values show mixing properties of thermal groundwater and shallow groundwater. Based on $^{87}$ Sr/$^{86}$ Sr values, Ca is thought to be originated from the dissolution of plagioclase. Reservoir temperature at depth is estimated to be 100~1$25^{\circ}C$ by calculation of equilibrium method of multiphase system. Therefore, the thermal groundwaters from the Yusung area were formed by heating at depths and evolved by water-rock interaction and mixing with shallow groundwater.

• Journal of Soil and Groundwater Environment
• /
• v.12 no.4
• /
• pp.1-7
• /
• 2007

Slug/bail tests were conducted in sand layer (sbt-1 well), silty sand layer (sbt-2 well), and mixed sand and silty sand layer (sbt-3 well). Hydraulic conductivity and specific storage coefficient were estimated through slug/bail tests. Pore volumes of groundwater level drawdown zone for bail test were estimated by using hydraulic conductivity and specific storage coefficient. KGS model was most suitable interpretation method of slug/bail tests. Average hydraulic conductivity for slug/bail tests were estimated to be $6.65{\times}10^{-5}$ m/sec in sbt-1 well, $6.33{\times}10^{-6}$ m/sec in sbt-2 well, and $3.72{\times}10^{-5}$ m/sec in sbt-3 well. Average specific storage coefficient for slug/bail tests were estimated to be 0.0225 in sbt-1 well, 0.0177 in sbt-2 well, and 0.0259 in sbt-3 well. Dimensionless time and dimensionless wellbore storage were estimated by use of transmissivity, storativity, test time, and specification of test wells. And, dimensionless drawdown were selected by parameter ${\alpha}\;and\;{\beta}$ parameter from Cooper et al. (1967). Radius of influence were estimated by estimated dimensionless time, dimensionless wellbore storage, and dimensionless drawdown. The average radius of influnce for slug/bail tests were estimated to be 1.377 m in sbt-1 well, 1.253 m in sbt-2 well, and 1.558 m in sbt-3 well. Pore volume at groundwater level drawdown zone by dummy withdrawal for bail tests were estimated to be $145,636cm^3$ in sbt-1 well, $71,561cm^3$ in sbt-2 well, and $100,418cm^3$ in sbt-3 well. Pore volume excepted well volume at groundwater level drawdown zone by dummy withdrawal for bail tests were estimated to be $145,410cm^3$ in sbt-1 well, $71,353cm^3$ in sbt-2 well, and $100,192cm^3$ in sbt-3 well.