• International Journal of Air-Conditioning and Refrigeration
• /
• v.15 no.4
• /
• pp.147-155
• /
• 2007

Mobile air conditioning systems work under widely changing operating conditions. To understand the system behavior under such dynamic conditions, a test facility that can impose transient loads as well as conducting dynamic measurements is needed. To test mobile air conditioning systems including their dynamic performance under various drive cycle patterns without using full scale vehicles in a wind tunnel, a new test facility, called "dynamic simulator," is described. It can replicate real vehicle operating conditions by interacting with the system being tested based on the measured system performance and subsequently adjusting the air properties returning to the test system based on the results of a numerical cabin model. A new dynamic simulator has been designed, constructed, and verified for performing dynamic tests. It was successful in controlling the temperature and relative humidity of the air returning to the test unit within ${\pm}0.7^{\circ}C$ and ${\pm}4%$ of their respective intended values. The verification test under the New European Driving Cycle demonstrated that detailed transient behavior of the mobile air conditioning system could be measured by using this dynamic simulator.

• Journal of the Korean GEO-environmental Society
• /
• v.23 no.9
• /
• pp.17-23
• /
• 2022

Using cement as a road subbase is economical, easily modified and supplemented and has excellent road pavement quality control. In addition, cement adheres well to sandy soils without adhesion, and it plays a role of permanently preserving adhesion in viscous soils with adhesion, so it can be widely applied as stable treatment with the advantages of increased strength, reduced compressibility. and improved durability. However, while cement is excellent in terms of strength for a road subbase, the material properties mean that it is difficult to maintain and reinforce when cracks or fractures occur due to dry shrinkage, and the pH increases in the ground due to hexavalent chromium eluting from cement. which can cause environmental problems such as groundwater contamination. Therefore, this study evaluates the usability of alternatives in the road base layer such as environmentally cementitious stabilizer and on-site soil generated from the site. We intend to reduce the environmental damage and evaluate the durability. To evaluate the applicability of the site, Environmental stability test and freeze-thaw test and wetting-drying test was conducted to evaluate the strength characteristics of alternative materials on the road through the limited performance evaluation of environmentally cementitious stabilizer. The test ranges were set at mixing ratios of 10%, 20%, and 30% and ages of three days, and 28 days old to evaluate the early strength and reference strength according to the mixing ratio of the environmentally cementitious stabilizer.

• Hwankyungkyoyuk
• /
• v.13 no.1
• /
• pp.133-141
• /
• 2000

This study was designed for middle school students in Su-Won City to find out their level of hope in environmental education and who had not been introduced to environmental skills and knowledge as a separate subject in their school curriculum. Additionally, the result of the study was expected to provide basic environmental education material to teachers who are on the front line in our environmental education efforts. The mother used to be very influential on her children's thinking and behavior to a large degree. Acknowledging these facts, students and their mothers were chosen for this study The questionnaire from each of the two groups were compared and studied. The questionnaire, comprised of 23 questions, was completed during the period of time from March 6 through March 11, 2000. The schools that participated in the study were 5 junior high schools in Su-Won City and the participants were students and their mothers. The questionnaires were given to 450 students and their mothers to be completed and returned. A total of 379 student questionnaires and 323 mother questionnaires were received for examination. The results of questionnaire were analyzed by using SPSS/PC 8.0 software program with Frequencies Analysis, Mean Analysis, Reliability Analysis, Correlation Analysis, Paired Samples T-test, and $\chi$$^2$-test. The questionnaires generated the following results. The reliability coefficient was 0.847 from the students and 0.895 from the mothers. The level of interest in an environmental education curriculum was 24.3% from students and 86.0% from mothers. Interestingly, the gender difference of level of interest in an environmental education curriculum was 25.7% from male and 23.1% from female. The difference in the environmental function levels between female and male students was statistically significant(t=-4.109, p<0.001). For mathematical skills in environmental functions, the students and mothers thought trash, air pollution, and lack of forest were problems however they showed inactive support and unreasonable attitudes toward the problems that they themselves pointed to for solving the problems. Under the environmental problems solving issue, the significance between two groups was 0.014(P<0.001) and the result dictates there was no correlation. The t-test showed no difference in environmental knowledge level between student genders. The knowledge level between students and mothers was related each other. The Paired Sample t-test between students versus mothers on environmental skills and knowledge was 0.000*(*P<0.001) and it showed there was correlation between the two groups. With this study, educating mothers should be noticed as a great priority in environmental education that will lead to a more positive environmental outlook from our students.

• Journal of The Korean Association For Science Education
• /
• v.28 no.5
• /
• pp.453-463
• /
• 2008

This study investigated the students' perceptions of environmental scientists and their work and the factors influencing the students' images of them by using the Draw-An-Environmental-Scientist-Test (DAEST). The DAEST was administered to 413 students in 10th and 11th grades selected from three high schools in Seoul. The results revealed that the students' images of environmental scientists were different from the stereotypical images of scientists. In the students' drawings, it was difficult to distinguish the gender and age of environmental scientists. Most students also perceived environmental scientists collecting data on environmental pollution by using experimental equipments and a laptop computer in the field. The students answered that the factors affecting their images of environmental scientists were mass media, school education, internet, and so on. According to the students' grade and gender, there were differences in the perceptions of environmental scientists and their work, and there were factors that influenced their images. Educational implications of these findings are discussed.

• The Korean Journal of Pesticide Science
• /
• v.18 no.1
• /
• pp.8-13
• /
• 2014

This study evaluated in vitro cytotoxicity of 5 pesticides, including 2 herbicides, 2 germicides, and an insecticide, as an alternative to the fish acute toxicity test. The in vitro cytotoxicity was tested using a neutral red uptake (NRU) assay with epithelioma papulosum cyprini (EPC) cells that originated from the epidermal tissue of Cyprinus carpio (common carp). An in vivo fish acute toxicity test was conducted according to OECD Test Guideline No. 203 using Aphyocypris chinensis (Chinese bleak), Oryzias latipes (Japanese medaka), and C. carpio. The results showed that the sensitivity of the cell viability assay for the pesticides was similar to the fish acute test in ranking order despite having approximately 10 times less absolute sensitivity. The $r^2$ correlation values were calculated as 0.38 (p = 0.26), 0.76 (p = 0.05) and 0.90 (p = 0.01) for A. chinensis, O. latipes, and C. carpio, respectively. These results suggested that the potential of EPC cell viability assay as an alternative to the fish acute toxicity test due to their good correlation and NRU assay is expected to serve as a useful tool for predicting acute fish lethality for pesticides if further studies with a large set of pesticides are conducted.

• Journal of the Korean GEO-environmental Society
• /
• v.6 no.1
• /
• pp.15-21
• /
• 2005

In this study, the utilization of coal-ash and phosphogypsum was considered as the evapotranspiration final landfill cover(ET cover) material. Cover material considered was the mixture of the weathered granite soil, coal-ash and phosphogypsum and so we sequentially performed the leaching test, column test and field model test to investigate the environmental effects of mixtures of coal-ash and phosphogypsum. In the leaching test, all materials had lower heavy metal concentration than the regulated threshold values. The column test and the review of related regulations were carried out to determine the optimum mixing ratio(OMR) and OMR was soil(4):coal-ash(1): phosphogypsum(1) on the volume base, which was applied to field model test. Field model tests were continued from February to June, 2004 in the soil box that was constructed with cement block. It was verified that coal-ash and phospogypsum mixed with soil was safe environmentally and the mixture of both wastes could improve the water retention capacity of cover materials.

• Geomechanics and Engineering
• /
• v.35 no.1
• /
• pp.67-80
• /
• 2023

Due to the nature of the conjunctive Cone Penetration Test(CPT), which does not verify the actual sample directly, geotechnical engineers commonly classify the underground geomaterials using CPT results with the classification diagrams proposed by various researchers. However, such classification diagrams may fail to reflect local geotechnical characteristics, potentially resulting in misclassification that does not align with the actual stratification in regions with strong local features. To address this, this paper presents an objective method for more accurate local CPT soil classification criteria, which utilizes C4.5 decision tree models trained with the CPT results from the clay-dominant southern coast of Korea and the sand-dominant region in South Carolina, USA. The results and analyses demonstrate that the C4.5 algorithm, in conjunction with oversampling, outlier removal, and pruning methods, can enhance and optimize the decision tree-based CPT soil classification model.

• Korean Journal of Occupational Health Nursing
• /
• v.28 no.4
• /
• pp.285-292
• /
• 2019

Purpose: This study aimed to examine the factors associated with behavior that reduces exposure to environmental hormones among nursing students. Methods: Data were collected from 160 nursing students in D and B cities, using self-report questionnaires. Data were analyzed using SPSS 22.0, and the analyses included descriptive statistics, t-test, ANOVA, Pearson's correlation coefficient test, and stepwise multiple regression. Results: Behavior that reduces exposure to environmental hormones differed significantly in terms of the participants' knowledge about environmental hormones. Behavior that reduces exposure to environmental hormones was negatively correlated with knowledge of environmental hormones, attitude towards pro-environmental behavior, and environmental self-efficacy; these factors were significant predictors of behavior that reduces exposure to environmental hormones, and accounted for 27.0% of the variance. Conclusion: Environmental self-efficacy was identified as the most significant factor affecting behavior that reduces exposure to environmental hormones in nursing students. Therefore, it is necessary to develop programs to improve pro-environmental behavior and environmental self-efficacy in nursing students.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.19 no.4
• /
• pp.536-544
• /
• 2016

The study on the precipitation particle distribution models in Korea for the environmental test and evaluation (T&E) from huge amount of measuring and reanalysis data is presented. Instead of related specifications of MIL-HDBK-310, with these models it can be possible to realize more realistic and efficient design and environmental T&E for the military and civil products especially for the atmospheric flying vehicles using in Korea.

• Journal of Korean Society of Environmental Engineers
• /
• v.36 no.5
• /
• pp.359-366
• /
• 2014

For an efficient and reasonable management scheme for protecting the soil environment, a soil ecological risk assessment (ERA) method should be developed prior to utilization, based on the contemporary uses and situations of each country. The Korean environmental policy focusing on soil protection is currently accelerating the development of the soil ecological risk assessment method. The soil ERA requires toxicological data on various trophic levels in the soil environment, and ultimately uses PNEC (Predicted No Effect Concentration), which is derived from collected toxicological data. Therefore, test species that are used to generate toxicity data are essential for conducting reliable ERA. This study aimed to select domestic test species for potential use in a reliable Korean ERA. Copper (Cu) and Nickel (Ni) were identified as target substances, with toxicity data (Cu, Ni) and standard test methods being collected to determine candidate species. The candidate species were first classified by soil trophic level, and then sorted into final domestic species. Forty out of 166 domestic species were determined as potential standard test species, whereas 17 out of 120 species were determined as potential Cu and Ni test species. Finally, this study presented potential soil test species based on the characteristics of the domestic soil environment, and established a preliminary step toward developing a reliable Korean soil ERA method.