• Economic and Environmental Geology
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• v.32 no.2
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• pp.203-208
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• 1999

The main objective of this study is to suggest a new assessment method of the influence of weathering due to salt crystallization on the engineering property of rock. For this purpose, various sources of salt and salt crystallization were investigated, and artificially accelerated weathering tests were carried out. In natural envionment, weathering rate is very slow and weathering process involves complex mechanisms. Therefore artificial weathering test is essential for systematic analysis. Arificial weathering test is defined as test which controls weathering rate and agents by controlling arificial environmental condition. In this study, salt crystallization test was selected among various artificial weathering test methods, for its important role in weathering. Change of various stone properties were detexted. The change of physical properties by salt crystallization were observed as follows : 72% in Brazilian tensile strength and 72% in Slake durability. These results explain the importance of salt crystallization in the mechanical behaviour and properties of stone.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.38-44
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• 2010

Shaking table tests were performed to reproduce the dynamic behavior of estuary barrage and its subbase soil which can be potentially damaged during earthquake loading. For understanding the vibration effect to the ground during earthquake, the model was formulated with 1/300 scale of prototype estuary barrage and subbase soil. Scott and Iai(1989) proposed the law of the similarity for similar experimental conditions. The laboratory model shaking table test was conducted under the vibration condition of simulated earthquake of 0.154g. The horizontal displacement on the structure was measured during the shaking table test. The pore water pressure was also monitored for the underground layers of soil. The field horizontal displacement and the pore water pressure can be predicted by using the results of the laboratory shaking table test.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1109-1114
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• 2008

To investigate the effect of sample size on coefficient of consolidation of non-homogeneous soil, the result of a large size consolidation test using a huge undisturbed sample with $1200mm(D){\times}2000mm(H)$ in dimension is compared with that of oedometer test using undisturbed small sample. In addition, test results are compared with those of same test using remold sample. Experimental results show that, due to the lump of sand/silt was mixed in sample, the coefficient of consolidation of undisturbed samples have a difference for each tests. Whereas, the difference of coefficient of consolidation between remolded large and small samples is not found. Because sample size affects the test results, sample must be carefully selected for non-homogeneous soil.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.163-166
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• 2003

This paper presents the results of a series of performance tests for the Stilting cryocooler. Infrared sensor systems incorporating cryocoolers are required to be qualified to the appropriate environmental specification. Linear drive Stilting cryocooler have matured to the stage of undergoing formal qualification test program The thermal environmental test of the Stilting cryocooler is presented in this paper. We performed that low and high temperature keeping test from －4$0^{\circ}C$ to ＋6$0^{\circ}C$ and operating test at high and low temperature cyclic range with acceptance tests performed at scheduled intervals. Cooling capacity was determined as a function of cooler components temperatures at the compressor, hot end and cold tip. Tests performed on this cooler have been successful with a measured cooling performance of more than 0.8W＠80K for 23$^{\circ}C$ ambient temperature with 40 $W_{ac}$ input power.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.7
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• pp.1155-1161
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• 2017

This study examines environmental performance of the arcing measurement module according to international standards. The module assesses the collected current performance using a computer system. The module is required to assess environmental impact resulting from electromagnetic waves, shock and temperature change during train operation. The test includes testing EMI/EMC, vibration, shock and temperature cycling for interface between trains and the arcing measurement module. The module test items were determined in compliance with the standards suggested by the International Electrotechnical Commission (IEC) and Europaische Norm (EN). This study describes the method of test, test equipment operation and how to choose relevant performance standards. The analysis and test results of environmental performance for the module based on computer system are described in this study.

• International Journal of Quality Innovation
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• v.7 no.1
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• pp.177-194
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• 2006

This research investigates the status of environmental design implementation in Taiwan's industries (Certified by ISO 14001) by employing questionnaire survey. The correlation between the degree of environmental design implementation in Taiwan's industries and the relevant entrepreneurial characteristics are examined. Twenty-six environmental design principles in four phases: design, manufacturing, sales and transportation, and disposal are used to define and assess the current status of environmental design. The data analysis methods applied to this research includes descriptive statistics, T-test, Chi-square test, and single-factor analysis of variance (ANOVA). It is evident that 21 out of the 26 environmental design principles are frequently and consistently employed by the manufacturers in Taiwan. The results indicate that environmental design implementation is becoming mature in Taiwan's industries.

• Journal of Korea Water Resources Association
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• v.46 no.3
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• pp.219-227
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• 2013

Time series data including change, jump, trend and periodicity generally have nonstationarity. Especially, various methods have been proposed to identify the trend about hydrological time series data. However, among various methods, evaluation about capability of each trend test has not been done a lot. Even for the same data, each method may show the different result. In this study, the simulation was performed for identification about the changes in trend analysis according to the statistical characteristics and the capability in the trend analysis. For this purpose, power test for the trend analysis is conducted using Men-Kendall test, Hotelling-Pabst test, t test and Sen test according to the slope, sample size, standard deviation and significance level. As a result, t test has higher statistical power than the others, while Mann-Kendall, Hotelling-Pabst, and Sen tests were similar results.

• Environmental Analysis Health and Toxicology
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• v.25 no.2
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• pp.153-159
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• 2010

Perfluorooctane sulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA) are the principal chemicals known as perfluoroalkyl acids (PFAs). Despite the widespread use of these compounds, relatively little is known about their fate and effects. The purpose of this study was to determine the toxic effects of PFOS and PFOA on Daphnia magna. In the acute toxicity test, D. magna were exposed for 48 hours at concentrations of 0, 30, 45, 67.5, 101.25 and 151.88 mg/L PFOS, and 0, 100, 160, 225, 337.5 and 506.25 mg/L PFOA, respectively. In the case of chronic toxicity test, D. magna were exposed through water for 21 days at concentrations of 0, 0.375, 0.75, 1.5, 3 and 6 mg/L PFOS, and 0, 1.25, 2.5, 5, 10 and 20 mg/L PFOA, respectively. Acute toxicity was assessed on the basis of immobility, while chronic toxicity was assessed on the basis of fecundity. The acute toxicity test on PFOS and PFOA showed that the values of $EC_{50}$ were 50.90 mg/L and 253.47 mg/L, respectively. In the chronic test, fecundity was reduced significantly at 1.5 mg/L of PFOS and 10 mg/L of PFOA, respectively. These results indicated that PFOS is more toxic to zooplankton than PFOA, and both chemicals have some hazard demonstrates risk for acute or chronic toxicity to freshwater organism.

• Korean Journal of Environmental Biology
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• v.30 no.4
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• pp.314-318
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• 2012

The aims of the present study were to estimate the possibility for toxicity test and compare acute toxicity of potassium dichromate in the larva stage of Neocaridina denticulata, Daphnia magna and the juvenile stage of Oryzias latipes. N. denticulate, a freshwater shrimp lives in Korea, is an indigenous species and considered to be useful for toxicity test. D. magna and O. latipes were recommended as a test species for the OECD test guideline. The 96 h-$LC_{50}$ potassium dichromate value was 0.62 mg $L^{-1}$ for the larva stage of N. denticulata and 168.44 mg $L^{-1}$ for the juvenile stage of O. latipes. The 48 h-$EC_{50}$ value was 1.27 mg $L^{-1}$ for the D. magna. The study was confirmed higher sensitivity of the larva stage of N. denticulata to potassium dichromate compared to the D. magna and the juvenile stage of O. latipes.

• Journal of Environmental Impact Assessment
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• v.4 no.2
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• pp.93-103
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• 1995

This study was carried out to suggest the best statistical test to analyze the trend in monthly water quality data. Traditional parametric tests such as t-test and regression analysis are based on the assumption that the underlying population has a normal distribution and regression analysis additionally assumes that residual errors are independent. Analyzing 9-years monthly COD data collected at Paldang in Han River, the underlying population was found to be neither normal nor independent. Therefore parametric tests are invalid for trend detection. Four Kinds of nonparametric statistical tests, such as Run Test, Daniel test, Mann-Kendall test, and Time Series Residual Analysis were applied to analyze the trend in the COD data, Daniel test and Mann-Kendall test indicated upward trend in COD data. The best nonparametric test was suggested to be Daniel test, which is simple in computation and easy to understand the intuitive meaning.