• Journal of Microbiology and Biotechnology
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• v.9 no.4
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• pp.464-468
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• 1999

The effectiveness of current biodegradation test methods for degradable polymers under controlled composting conditions was studied in regards to the test temperature and compost condition. When biodegradability tests for the natural (starch, cellulose, PHB/HV) and synthetic (PCL, SG, PLA) polymers were conducted at temperature levels of 35 and $55^{\circ}C$ with compost cured at ambient temperature, the degradations of cellulose and starch were higher at $35^{\circ}C$ because of the priming effect. On the other hand, degradations of other polymers were higher at $55^{\circ}C$. In the biodegradation test at $55^{\circ}C$, compost harvested right after the thermophilic degradation stage showed higher biodegradation activities than the cured compost for both the synthetic aliphatic polyester (SG) and a natural polymer, cellulose. These results suggest that the biodegradation test conducted at $55^{\circ}C$ with the compost, harvested right after the thermophilic degradation stage during composting, showed the highest biodegradation activity under controlled composting conditions.

• Journal of the Korea Safety Management & Science
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• v.15 no.1
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• pp.109-120
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• 2013

As information-oriented industry has been developed and electronic devices has come to be smaller, lighter, multifunctional, and high speed, the components used to the devices need to be much high density and should have find pattern due to high integration. Also, diverse reliability problems happen as user environment is getting harsher. For this reasons, establishing and securing products and components reliability comes to key factor in company's competitiveness. It makes accelerated test important to check product reliability in fast way. Out of fine pattern failure modes, failure of Electrochemical Migration(ECM) is kind of degradation of insulation resistance by electro-chemical reaction, which it comes to be accelerated by biased voltage in high temperature and high humidity environment. In this thesis, the accelerated life test for failure caused by ECM on fine pattern substrate, $20/20{\mu}m$ pattern width/space applied by Semi Additive Process, was performed, and through this test, the investigation of failure mechanism and the life-time prediction evaluation under actual user environment was implemented. The result of accelerated test has been compared and estimated with life distribution and life stress relatively by using Minitab software and its acceleration rate was also tested. Through estimated weibull distribution, B10 life has been estimated under 95% confidence level of failure data happened in each test conditions. And the life in actual usage environment has been predicted by using generalized Eyring model considering temperature and humidity by developing Arrhenius reaction rate theory, and acceleration factors by test conditions have been calculated.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.46-53
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• 2013

In this study, the analysis of electromagnetic environment of goheung aviation center was performed. If the test object has restrictions to be tested in indoor test facility, open area test site can be used to perform EMC test. Open area test site shall have no obstacles that can generate or reflect the electric field so as to prevent the measurement result from being influenced by unnecessary field. Goheung aviation center is surrounded by fields, and has no buildings that can reflect electric field, so the center can be a good candidate for open area test site. Ambient noise at Goheung aviation center was measured, and the result show that the center has good electromagnetic environment to perform EMC test for large volume object.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.943-953
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• 2012

Because of their unique properties, nano-sized metallic nanomaterials (NMs) have been used in extensive applications of biomedicine, electronics, optics, engineering, and personal care products. Accordingly, with the increasing release of NMs into the environment, numerous studies of nanoecotoxicity have been conducted. Fish embryo toxicity test (FET) has many benefits in evaluating toxicity of NMs as an alternative to a whole-body test in fish. In this study, we collected and analyzed the toxicity studies of metallic NMs on freshwater fish embryos. Most studies have demonstrated that metallic NMs are highly toxic during the early development of fish embryos. However, it should be noted that the results for the same NMs on the same test species show variation due to differences in the size or surface properties of the test NMs and exposure conditions. For the safe use of metallic NMs, we need to analyze their effects based on their properties, test species, environmental media, and diverse conditions.

• Environmental Analysis Health and Toxicology
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• v.9 no.3_4
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• pp.91-101
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• 1994

In order to evaluate the ecotoxicological harzardousness of synthetic surfactants on Han river, Jung-ryang and Jin-Wi stream, we used the Ecotoxicological Risk Quotient (ERQ). The chemical harzardousness is evaluated by the balance of the toxicity and concentration in the environment.. Then, ERQ is defined as follows; ERQ = - log ( Concentration in the environment / Effective concentration in the test ) ERQ of chemical is a logtrighmic value of ratio of a chemical concentration and the toxicity in the laboratory. In case of small ERQ, tie chemical harzardousness is high. If ERQ equals O, the same biological effect as in the laboratory test will be observed in the enviromment by the chemicals. ERQ values of the chemicals were calculated using the maximum concentration in water environment which were cited from the annual report by our ministry of environment, and EC$_{50}$ of Daphnia magna (water flea; acute immobilization test) LC$_{50}$ of Oryzias latipes (fish; acue toxicity test) and EC$_{50}$ of chlorella vulgaris (alga; growth inhibition test), which were taken from the annual report of "Chemical in environment" by Japan EA. Liner alkylbenzene sulfonate (determined to MBAS) showed the high average values with more than 2.0 to three species in Han river and Jin-wi stream, and these results mean to be favorable to environmental safety. The areas of Jung-ryang stream were polluted, as the average values of ERQ were less than 2.0 with equal to three species, and attention should be paid. Therefore, they must be inspected again because their concentration in the environment may have changed during that period. The chemical harzardousness can be numerated with ERQ, and it can be a help to find the chemicals that should be kept under observation and to see whether the chemical pollution is improved or worsened. The determination of the chemical concentration in the environment and toxicity are essential for the effective use of ERQ.se of ERQ.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.5
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• pp.344-357
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• 2019

Operational failures may occur even though there had been no signs of defect during the manufacturing process, which may be caused due to exposure to environmental stress which had not been addressed properly during the design process. It is thus necessary to perform environmental testing to determine the cause of the failures. Environmental testing is also used to determine whether a materiel has enough tolerance to the environmental stress during its operation. In this study, the method and level for each environmental testing are properly tailored and applied to a fight aircraft intended to operate in ROK (Republic of Korea), based on the MIL-STD-810G Change 1. Since each part of a fighter aircraft may be exposed to each different environment, LRUs (Line Replaceable Units) exposed to similar environment should be tested similarly. In addition, the decision whether to apply specific test and the tailoring technique in test level were derived for natural and induced environments, respectively. As a fight aircraft is assumed to operate in ROK, the tailoring of test methods and test level to fit to the environment in Korean peninsula is necessary. Further research is needed in determining a specific procedure and a specific level in a test method, and also in determining the test sequence, when conducting more than one is needed, because it can alter test results and it hence becomes an essential element in test design.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.4 s.310
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• pp.39-49
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• 2006

This paper proposes an efficient verification environment of PCI Express controller that is the future I/O interface. This verification environment consists of a test vector generator, a test bench, and two abstract memories. We also define the assembler set to generate the verification scenarios. In this paper, we propose the random test environment which consists of a random vector generator, a .simulator part, and a compare engine. This verification methodology is useful to find the special errors which are not detected by the basic-behavioral test and hardware-design test.

• Journal of the military operations research society of Korea
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• v.30 no.2
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• pp.108-121
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• 2004

This paper deals with a procedure of changing the current inspection & replacement periods for ROKAF aircraft parts. ROKAF is mostly operating aircraft of foreign makes, and takes maintenance actions according to Technical Orders(TO.) published by foreign aircraft manufacturers. Therefore ROKAF inspects and replaces specific parts at the time noticed from T.O.. These inspection and replacement periods are determined by manufacturers according to the standard operating environment and parts' durability. But the standard operating environment Is different from operator's environment. Because of this difference, the inspection and replacement periods have to be changed according to operators' operation environment. It is resonable that the manufacturer, having design materials and life test data of parts, changes those periods together with materials of operators' operation environment. But we have many difficulties in obtaining the design materials and life test data. Then this paper proposes a procedure of changing the periods of aircraft's parts with life data obtained during operating aircraft. For the reliability analysis, a software of RELEST (Reliability Estimation Version 1.0) is used.

• Journal of People, Plants, and Environment
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• v.22 no.6
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• pp.691-698
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• 2019

This study is to examine the effect of improving the forest therapy program for adolescents using forest healing resources (focused on improving index of greenness for adolescents). The participants were 30 students from in the control group that participated in the 2018 program, and 51 students in experimental group that participated in the improved program in 2019. The questionnaire, developed by Korea Forest Welfare Institute, was comprised of items on general matters, index of greenness, restorative environment, positive emotion, negative emotion, facial expression and psychological assessment. The control group had 30 and the experimental group had 49 valid copies of the questionnaires. As a result of the paired sample t-test for each group, the control group showed a significant increase in all categories except restorative environment. In the experimental group, all categories significantly improved to a higher level (p <.01). An independent sample t-test (one-tailed test) was performed to test the effect of the forest therapy program with improved index of greenness. As a result, the index of greenness increased by 0.73 points(t=2.555, p <.01) and restorative environment by 1.01 points (t=2.567, p <.01), showing statistical significance. Negative emotion increased by 0.04 points (t=0.183, p >.05), which was not significant. On the other hand, positive emotion decreased by 0.42 points (t=-1.918, p <.05), facial expression by 0.57 points (t=-1.775, p <.05), and psychological assessment by 0.29 points (t=-0.981, p >.05), showing significance in positive emotion and facial expression. However, all the decreased items showed significant improvements between the pretest and posttest scores of the experimental group.

• Journal of Soil and Groundwater Environment
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• v.15 no.5
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• pp.8-15
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• 2010

The purpose of this research is to check the validation of an auto-analysis method combined with aqua regia digestion apparatus for improvement of water distillation method used as a fluorine test of soil. Fluorine contents of CaO used in the pretreatment course of water distillation method were 120 mg/kg ~ 5,064 mg/kg at the blank test, which was exceeded up to maximum 12.5 times of the soil standard, so it was estimated due to a effect of fluorine existing as impurities of CaO. The recovery test of the same samples indicated that water distillation method and auto-analysis method were 134.5mg/kg and 161.7mg/kg respectively, the recovery ratio of the latter was 16.8% higher than the formal. The validation test of two methods satisfied the standard, but auto analysis method was excellent more than distillation method. Also, auto analysis method could save a analysis time up to maximum 4.7 times by comparison with water distillation method.