• Journal of the Korean GEO-environmental Society
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• v.11 no.11
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• pp.47-54
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• 2010

Nowadays, geosynthetics for reinforcement and protection are widely applied to the waste landfill site. Current research indicates the potential for progressive failure in geosynthetic-soil system depends on the interface shear strength governed by several intrinsic factors such as moisture, normal stress, chemical, etc. In particular, the effect of the acidity and basicity from the leachate is intensively reviewed to assess the chemical reaction mechanism of interface shear strength under the cyclic loading condition. New multi-purpose interface apparatus(M-PIA) has been manufactured and the cyclic direct shear tests using submerged geosynthetics and soils under the different chemical conditions have been performed, consequently, the thickness of interface and shear stress degradation are verified. The basic schematic of the Disturbed State Concept(DSC) is employed to estimate the shear stress degradation in the interface, then, normalized disturbed function is obtained and analyzed to describe the shear stress degradation of geosynthetic-soil interface with chemical influence factors under dynamic condition.

• Toxicological Research
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• v.8 no.1
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• pp.29-40
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• 1992

The recombinant glycoprotein, LBD-005 (Lucky R & D Center, Biotechnology)stimulates the growth of stem cells and activates the development of the hematopoietic cell in a similar manner to the naturally occurring GM-CSF. This test was conducted to investigate if LBD-005 had any effect on fertility in male and female rats. Sprague-Dawley rats(88 of each sex) bred at KRICT, were dosed subcutaneously, at a volume of 2ml/kg body weight with LBD-005 at 0, 250, 500 or 1, 000mg/kg body weight. The male rats were dosed, from 6 weeks of asge, for 60 days prior to mating.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.5
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• pp.509-514
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• 2003

We performed the experiment to determine the effective factors, such as the initial concentration of protein, pore size of air distributor, SAV (superficial air velocity), pH, salts and temperature related to foaming characteristics. The foam height in a foam generator was increased with the increase of the initial protein concentration and the decrease of pore size. As SAV was increased, the foam height was increased, and the optimum SAV was 0.84 cm/sec. The foam height was highest in the acid region and it was increased with the increase of salt concentration of NaCl and $NaHCO_3.$ The removal efficiencies of TSS (total suspended solid) and turbidity decreased with the increase of the initial protein concentration in the batch foam separator.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.79-89
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• 1998

In determining optimal cutting condition for face milling operation, tool wear is an important factor. For the purpose of establishing the relationship between various machining factors and tool wear, cutting tests have been performed. As a result, hardness and chemical composition of workpiece material, chemical composition and grain size of cutting tool and cutting speed have been selected as machining factors. In addition, relationship between feed rate and workpiece hardness has been observed. Prior to utilizing cutting conditions recommended by ‘Machining Data Handbook(MDH)’ as a knowledge base, an analysis for the validity of the MDH has been provided. Based on this analysis, tool life criteria applied by MDH has been modified. Finally, using MDH recommended data for neural network trainning, the results from the trained neural network for optimal cutting condition for some given workpiece and cutting tool can be used as reference cutting conditions.

• Journal of the Korean Chemical Society
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• v.67 no.1
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• pp.28-32
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• 2023

The reaction conditions optimization, including the temperature of the reaction, amount of catalyst required, and reaction time for the linoleic acids (LAs) and conjugated linoleic acids (CLAs) production by catalytic dehydration of castor oil via saponification was investigated by response surface methodology (RSM). It was confirmed that all three parameters (temperature, time, and amount of catalyst) were influential factors in isolating LAs and CLAs. When the temperature was increased, the iodine value increased, and the reaction time and catalyst amount increased. The optimal reaction conditions were: 240 ℃, 2.2 h reaction time, and 7 wt% catalyst amount. The maximum iodine value reached 156.25 with 91.69% conversion to the essential fatty acids.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.492-498
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• 2015

The long-term changes in the soil properties are closely related to the policy direction and the national program for the soil management. In this study, chemical properties of paddy soils in Jeonnam province were investigated at four-year interval since 1999 and the factors affecting change of chemical properties were analyzed in relation to the soil management policies. Chemical fertilizers supplied to Jeonnam province reduced by 57% in 2013 as compared with 1999, and the ratio of Jeonnam province to the national fertilizer supply gradually decreased to 14.1% in 2013 from 17.6% in 1999 due to national policies to reduce use of chemical fertilizers in the 2000s. In the chemical analysis of paddy soils in Jeonnam province, pH value tended to increase gradually within the optimal range. Available phosphate and exchangeable potassium content were always higher than the optimal range and showed no significant difference since 1999. Organic matter, exchangeable calcium and available silicate content were found to be lower than average content in the whole country as well optimal range for rice cultivation in 1999, but were higher than average content in the whole country and optimal range in 2011 because of faster rate of increase in Jeonnam province than the other region since the mid-2000s. The cause of increase in organic matter, exchangeable calcium and available silicate contents is considered to be the increased use of green manure crops and by-products fertilizer as an alternatives for conventional application of chemical fertilizers and soil amendment such as silicate fertilizer for agronomic control of the disease and insect pest in rice cultivation of environmentally-friendly agriculture.

• Geomechanics and Engineering
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• v.17 no.5
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• pp.465-473
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• 2019

Biocementation due to the microbially induced calcium carbonate precipitation (MICP) process is a potential technique that can be used for soil improvement. However, the effect of biocementation may be affected by many factors, including nutrient concentration, bacterial strains, injection strategy, temperature, pH, and soil type. This study investigates mainly the effect of chemical concentration on the formation of calcium carbonate (e.g., quantity, size, and crystalline structure) and unconfined compressive strength (UCS) using different treatment time and chemical concentration in the biotreatment. Two chemical concentrations (0.5 and 1.0 M) and three different treatment times (2, 4, and 8 cycles) were studied. The effect of chemical concentrations on the treatment was also examined by making the total amount of chemicals injected to be the same, but using different times of treatment and chemical concentrations (8 cycles for 0.50 M and 4 cycles for 1.00 M). The UCS and CCC were measured and scanning electron microscopy (SEM) analysis was carried out. The SEM images revealed that the sizes of calcium carbonate crystals increased with an increase in chemical concentrations. The UCS values resulting from the treatments using low concentration were slightly greater than those from the treatments using high concentration, given the CCC to be more or less the same. This trend can be attributed to the size of the precipitated crystals, in which the cementation efficiency increases as the crystal size decreases, for a given CCC. Furthermore, in the high concentration treatment, two mineral types of calcium carbonate were precipitated, namely, calcite and amorphous calcium carbonate (ACC). As the crystal shape and morphology of ACC differ from those of calcite, the bonding provided by ACC can be weaker than that provided by calcite. As a result, the conditions of calcium carbonate were affected by test key factors and eventually, contributed to the UCS values.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.3
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• pp.79-86
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• 2021

Purpose : This study was conducted to provide fundamental data to prepare for countermeasure to protect health of workers in the dental clinics from hazardous chemical substance, and to assess effecting factors on management of Material Safety Date Sheet(MSDS) and handling of hazardous chemical substance among workers in dental clinics. Methods : This study was carried out a survey with structured self-administered questionnaire which was consisted of 7 questions about the management of MSDS, 9 questions about recognition and practice of hazardous chemical substances in dental clinics, and 7 questions about general characteristics. Total subjects of this study were 204 adult who workers in dental clinics located in Busan and Gyeng-nam province area. The collected data were analysed using the SPSS statistical package program (ver. 23.0). Results : The factor that positively affected factor on recognition and practice of hazardous chemical substances in dental clinics has experience that has been institutional health-care accreditation. The factor that positively affected the management of MSDS has experience that has been institutional health-care accreditation. Conclusion : It is necessary to prepare countermeasures such as campaign and education on cognition of general chemical substances, and also the author concern that it should be perform the education on handling of hazardous chemical substances in dental clinics for more effecting management of MSDS. In order to improve the management of MSDS and improve the awareness and safety of chemicals, it is necessary to encourage the implementation of the institutional health-care accreditation system or prepare guidelines for the management of MSDS.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.35-43
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• 2024

With continuous advancements in industry, science, and technology, there is a steady increase in the number and utilization of new chemicals. The growing societal emphasis on chemical safety management is paralleled by an increasing public demand for robust safety measures. While various ministries at the government level oversee the safety management of chemical substances, the occurrence of accidents related to chemical substances remains frequent each year due to problems such as aging facilities and careless handling. Upon analyzing domestic chemical accident cases, incidents occurred predominantly in the sequence of leakage, explosion, fire, and others. The main causes of these accidents were examined, revealing facility defects and non-compliance with safety management as the primary contributing factors. In this study, Hazard and Operability Analysis (HAZOP) was employed to identify hazardous risk factors associated with the handling of hydrofluoric acid in workplaces, and a risk assessment was performed using Bow-Tie method. Based on the results of this study, it is expected to enhance safety management plans aimed at preventing chemical accidents in workplaces dealing with similar facilities. Ultimately, these insights contribute to the development of an advanced chemical safety management system, capable of proactively preventing potential chemical accidents.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.10
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• pp.812-816
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• 2000

It is very important to understand the correlation of between inter dielectric(ILD) CMP process and various facility factors supplied to equipment to equipment system. In this paper, the correlation between the various facility factors supplied to CMP equipment system and ILD-CMP process was studied. To prevent the partial over-polishing(edge hot-spot) generated in the wafer edge area during polishing, we analyze various facilities supplied at supply system. With facility shortage of D.I water(DIW) pressure, we introduced an adding purified $N_2$(P$N_2$)gas in polishing head cleaning station for increasing a cleaning effect. DIW pressure and P$N_2$gas factors were not related with removal rate, but edge hot-spot of patterned wafer had a serious relation. We estimated two factors (DIW pressure and P$N_2$gas) for the improvement of CMP process. Especially, we obtained a uniform planarity in patterned wafer and prohibited more than 90% wafer edge over-polishing. In this study, we acknowledged that facility factors supplied to equipment system played an important role in ILD-CMP process.