• Journal of Soil and Groundwater Environment
• /
• v.10 no.3
• /
• pp.38-45
• /
• 2005

The feasibility of stimulating in situ aerobic cometabolic activity of indigenous microorganisms was investigated in a trichloroethylene (TCE)-contaminated aquifer. A series of single-well natural drift tests (SWNDTs) was conducted by injecting site groundwater amended with a bromide tracer and combinations of toluene, oxygen, nitrate, ethylene and TCE into an existing monitoring well and by sampling the same well over time. Three field tests, Push-pull Transport Test, Drift Biostimulation Test, and Drift Surrogate Activity Test, were performed in sequence. Initial rate of toluene degradation was much faster than the rate of bromide dilution resulting from natural groundwater drift, indicating stimulation of indigenous toluene-oxidizing microorganisms. Transformation of ethylene, a surrogate probing overall activity of TCE transformation, was also observed, and its transformation results in the production of ethylene oxide, suggesting that some tolueneoxidizing microorganisms stimulated may express a orthomonooxygenase enzyme. Also in situ transformation of TCE was confirmed by greater retardation of TCE than bromide after the stimulation of toluene-oxidizing microorganisms. These results indicate that, in this environment, toluene and oxygen additions stimulated the growth and aerobic cometabolic activity of indigenous microorganisms expressing orthomonooxygenase enzymes. The simple, low-cost field test method presented in this study provides an effective method for conducting rapid field assessments and pilot testing of aerobic cometabolism, which has previously hindered application of this technology to groundwater remediation.

• Journal of The Korean Association For Science Education
• /
• v.19 no.1
• /
• pp.107-116
• /
• 1999

The effects of clarified mapping strategy and placement of analog on middle school students' conceptual understanding were investigated. According to the usage of clarified mapping strategy and the sequence in presenting analogy, four types of learning materials were developed and pilot tested. Prior to the treatment, the field dependence-independence test was administered and a previous achievement test scores were obtained. The scores were used as blocking variables. The learning materials were read by randomly assigned middle school students (N=111), and the conceptions test was administered immediately and four weeks later. In the recall problems of immediate and retention test, there were no significant differences. In the application problems of immediate and retention test, however, the students learned with clarified mapping strategy scored significantly higher than those with analog-only. Field-independent students learned with clarified mapping strategy scored significantly higher in the immediate application than those with analog-only, and higher-level students learned with clarified mapping strategy scored significantly higher in the retention application than those with analog-only. In the immediate application, higher-level students learned analog first with clarified mapping strategy scored significantly higher in the immediate application than those learned target concept first with clarified mapping strategy. However, lower-level students learned target concept first with clarified mapping strategy scored significantly higher than those learned analog first with clarified mapping strategy.

• Journal of Korean Institute of Industrial Engineers
• /
• v.29 no.2
• /
• pp.179-189
• /
• 2003

Gate poly-silicon critical dimension is a prime characteristic of a metal-oxide-semiconductor field effect transistor. It is important to achieve the uniformity of gate poly-silicon critical dimension in order that a semiconductor device has acceptable electrical test characteristics as well as a semiconductor wafer fabrication process has a competitive net-die-per-wafer yield. However, on gate poly-silicon critical dimension, the complexity associated with a semiconductor wafer fabrication process entails hierarchical variance components according to run-to-run, wafer-to-wafer and even die-to-die production unit changes. Specifically, estimates of the hierarchical variance components are required not only for disclosing dominant sources of the variation but also for testing the wafer-level uniformity. In this paper, two experimental designs, a two-stage nested design and a randomized complete block design are considered in order to estimate the hierarchical variance components. Since gate poly-silicon critical dimensions are collected from fixed die positions within wafers, a factor representing die positions can be regarded as fixed in linear statistical models for the designs. In this context, the two-stage nested design also checks the wafer-level uniformity taking all sampled runs into account. In more detail, using variance estimates derived from randomized complete block designs, Duncan's multiple range test examines the wafer-level uniformity for each run. Consequently, a framework presented in this study could provide guidelines to practitioners on estimating the hierarchical variance components and testing the wafer-level uniformity in parallel for any characteristics concerned in semiconductor wafer fabrication processes. Statistical analysis is illustrated for an experimental dataset from a real pilot semiconductor wafer fabrication process.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.4
• /
• pp.51-59
• /
• 2010

This article is a case study for the example of the foundation design, in the project area of the silty sand layer that is spread shallowly with loose status, to make the site for a structure and build it up. The site is located on the dredged and reclaimed land in Gun-San and In-Cheon that is formed the silty sand layer with loose status range around 10 meters underground level, the solid ground for the lower pile is shown around 20 meters underground level. Therefore, this area has to be done by ground improvement when applying for the shallow method of foundation. Dynamic compaction method considering the conditions of the design loads in each zone has to be decided through comparative review on the method of foundations and pilot field test was conducted, and drilling investigation and plate bearing test were achieved as well. The analysis results of the tests prove that stability against bearing capacity was acquired by ground improvement effect.

• Journal of Soil and Groundwater Environment
• /
• v.20 no.6
• /
• pp.103-110
• /
• 2015

Nitro-aromatic Compounds (NACs) of explosives are structurally non-degradable materials that have an adverse effect to humans and ecosystems in case of emissions in natural due to the strong toxicity. In this study, batch test in the laboratory-scale has been conducted to find some process parameters of alkaline hydrolysis by considering the characteristics of NACs which are unstable in a base status and field application evaluation have been performed on the batch test results. Based on the experimental results of both laboratory and pilot-scale test, the optimum conditions of parameters for the alkaline hydrolysis of soils contaminated with explosives were pH 12.5, above the solid-liquid ratio 1 : 3, above the room temperature and 30 minute reaction time. In these four process parameters, the most important influencing factor was pH, and the condition of above pH 12.0 was necessary for high contaminated soils (more than 60 mg/kg). In the case of above pH 12.5, the efficiency of alkaline hydrolysis was very high regardless of the concentrations of contaminated soils. At pH 11.5, the removal efficiency of TNT was increased from 76.5% to 97.5% when the temperature in reactor was elevated from room temperature to 80℃. This result shows that it is possible to operate the alkaline hydrolysis at even pH 11.5 due to increased reaction rate depending on temperature adjustment. The results found in above experiments will be able to be used in alkaline hydrolysis for process improvement considering the economy.

• Journal of The Korean Association For Science Education
• /
• v.18 no.4
• /
• pp.545-555
• /
• 1998

The improvement of process skills has been one of the most important goals in secondary science education. To achieve this goal, it is essential to develop an instrument for evaluating inquiry skills in addition to improving science curricula, inquiry teaching methods, and other educational environment. There are a lot of instruments in testing science process skills in Korea as well as America and Europe. However, it has been difficult to find the instruments that have a characteristic in content and form. The purpose of this study is to develop a valid and reliable instrument for evaluating science process skills using line graph. This study examined the whole body of scientific process and identified 6 component skills. Three or four items for each component process skills were developed and revised by pilot test and field test. The instrument is considered valid and reliable, for the content validity is 78% and the reliability(KR-20) is 0.82. The discrimination index is 0.57 and difficulty index is 0.47, which also suffice the criteria of good test.

• Journal of Ocean Engineering and Technology
• /
• v.30 no.6
• /
• pp.526-534
• /
• 2016

This study had the goal of designing onboard structures for a pre-pilot mining test (PPMT), which is required for the commercialization of the deep-sea mining industry. This PPMT is planned to validate the performance of a hydraulic lifting system and verify the concept of operating through a moon-pool in the east sea, Korea. All of the onboard equipment and facility were designed by KRISO. Because the test was performed at the first development, it is difficult to determine what risk will occur in the facility. Therefore, risk-based design is required in the facility for the PPMT, which includes the facility layout, failure mode and effect analysis (FMEA), and risk reduction plan. All of the expected performances of the lifting system itself and the onboard facilities were qualitatively validated using the risk-based design.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.64 no.2
• /
• pp.27-35
• /
• 2022

Based on the current status of groundwater usage in the dry season through field surveys, this study tried to suggest countermeasures to reduce groundwater usage and to improve the water quality of baseflow from agricultural fields. For this purposes, basins with water curtain cultivation preceded were targeted where decreases of groundwater due to continuous use of groundwater in spring and winter annually observed. From monitoring groudwater usage of the study watershed, 130,058, 130,105 m³/day of water was pumped in during the water curtain cultivation period (October-February) in the Shindun, Seokwon watershed respectively. And the pilot application of the smart automated sensor-based water curtain cultivation system (smart WC system) developed in this study to reduce groundwater consumption has been conducted. As a result, the efficiency of the smart WC system when threshold temperature is set as 6.3 ℃ was 21.1% compared to conventional cultivation and efficiency increased as threshold temperature gets lower. Lastly, in this study, culvert drainage and Bio-filters were installed and rainfall monitoring was performed 15 times in order to analyze the baseflow securement and pollutant loads behavior. As a result, the test-bed with culvert drainage and Bio-filter installed together generated 61.4% more baseflow (4.974 m³) than the test-bed with only culvert drainage was installed (3.056 m³). However, the total pollutant load of all water quality contents (BOD, COD, T-N, TOC) except for the SS and T-P was found to be greater in the culvert drain and Bio-filter installed than in the culvert drain test-bed.

• The Journal of Information Systems
• /
• v.24 no.2
• /
• pp.117-138
• /
• 2015

Purpose The number of Tablet PC users has recently increased in steep, which started to offer media companies more opportunities to enter into a new business field. Based on Information System Success model, this study finds that tablet magazine's quality factors influence perceived usefulness, user satisfaction and intention of continuous use. Design/methodology/approach We conducted a survey for 20-40's Tablet PC users. After pilot study, we analyzed the main survey data by using SPSS 18.0 and AMOS 18.0, and employed structural equation modeling to test the hypotheses. Findings Our research results are summarized as follows : First, information quality has a positive impact on user satisfaction, but not on perceived usefulness. Second, service quality has a positive impact on perceived usefulness, but not on user satisfaction. Third, perceived usefulness positively influences user satisfaction. Fourth, user satisfaction positively influences the intention of continuous use. In particular we found that Tablet PC usage experience had a moderating effect on the relationship between perceived usefulness and user satisfaction.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.12
• /
• pp.2199-2210
• /
• 2017

Soil burial is the most widely used disposal method for infected pig carcasses, but composting has gained attention as an alternative disposal method because pig carcasses can be decomposed rapidly and safely by composting. To understand the pig carcass decomposition process in soil burial and by composting, pilot-scale test systems that simulated soil burial and composting were designed and constructed in the field. The envelope material samples were collected using special sampling devices without disturbance, and bacterial community dynamics were analyzed by high-throughput pyrosequencing for 340 days. Based on the odor gas intensity profiles, it was estimated that the active and advanced decay stages were reached earlier by composting than by soil burial. The dominant bacterial communities in the soil were aerobic and/or facultatively anaerobic gram-negative bacteria such as Pseudomonas, Gelidibacter, Mucilaginibacter, and Brevundimonas. However, the dominant bacteria in the composting system were anaerobic, thermophilic, endospore-forming, and/or halophilic gram-positive bacteria such as Pelotomaculum, Lentibacillus, Clostridium, and Caldicoprobacter. Different dominant bacteria played important roles in the decomposition of pig carcasses in the soil and compost. This study provides useful comparative date for the degradation of pig carcasses in the soil burial and composting systems.