• Journal of Microbiology and Biotechnology
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• 제9권4호
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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.

• 대한안전경영과학회지
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• 제15권1호
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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.

• 항공우주기술
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• 제12권1호
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• pp.46-53
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• 2013

일반적으로 전자파 환경시험은 외부 전자기 환경의 영향을 배제하기 위하여 전자파 차폐룸에서 시험을 수행하지만, 시험체의 크기가 너무 크거나, 배기가스를 방출하는 등의 제약이 있을 경우 전자파 차폐룸에서 시험이 어려울 수 있으며, 야외 시험장을 이용할 수 밖에 없다. 야외 시험장은 측정 결과에 영향을 미칠 수 있는 전파 반사체, 전파 잡음 등이 시험장 내에 존재하지 않는 것이 이상적이지만 IT, 무선 통신 산업이 발달됨에 따라 기존의 야외 시험장은 수많은 생활전자파노이즈에 오염되어 있는 실정이다. 고흥 항공센터의 경우 도심과 떨어져 있고, 주변이 농경지로 둘러싸여 있어 전자파환경이 청정할 것으로 예상되며, 따라서 대형시험체의 전계강도를 측정할 수 있는 야외 시험장으로 활용이 가능할 수 있다. 이를 확인하기 위해 고흥 항공센터의 전자파환경을 측정하였으며, 30 MHz 이상의 주파수대역에서는 라디오, TV, 핸드폰 등 소스가 분명한 주파수를 제외하고는 대체적으로 깨끗한 결과를 보였으며 야외 시험장으로 좋은 역할을 할 수 있음을 확인하였다.

• 한국물환경학회지
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• 제28권6호
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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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• 제9권3_4호
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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.

• 한국항공우주학회지
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• 제47권5호
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• pp.344-357
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• 2019

운용상 고장은 제조 시 아무런 문제가 나타나지 않더라도 발생할 수 있으며, 설계 절차에서 고려하지 못했던 환경적 스트레스가 원인일 수 있다. 따라서 환경시험은 이러한 고장의 원인을 판단하기 위해 필수적으로 수행되어야 한다. 또한 환경시험은 군수품이 운용 시 환경적 스트레스로부터 충분한 저항력을 가지고 있는지 판단하는데 사용된다. 본 연구에서는 MIL-STD-810G Change 1기반의 환경시험법과 시험수준을 대한민국에서 운용될 전투기 개발에 맞게 테일러링하여 적용한다. 전투기의 각기 다른 파트는 각각 다른 환경에 노출될 수 있으므로 노출되는 환경이 다른 구성품, 또는 LRUs (Line Replaceable Units) 별로 환경시험을 진행해야 한다. 본 연구에서는 비슷한 환경에 노출되는 LRU 수준에서 시험법 적용여부 및 시험수준의 테일러링 기법을 도출하였으며, 자연, 유도 환경을 나누어 기술하였다. 대한민국에서 운용하는 전투기를 가정하였으므로 한반도의 환경에 맞는 시험법과 시험 수준에 대한 테일러링이 필수적이다. 한 시험법 내에 있는 여러 가지 절차와 시험 수준에 대한 테일러링에 대한 추가적인 연구가 필요하다. 또한 여러 가지의 시험법을 수행할 때 시험순서가 결과에 영향을 미칠 수 있어 환경시험 설계에 있어 필수적인 요소가 되므로 시험순서 결정에 대한 연구도 필요하다.

• 전자공학회논문지CI
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• 제43권4호
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• pp.39-49
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• 2006

본 논문에서는 차세대 입출력 인터페이스인, PCI 익스프레스 컨트롤러의 기능 검증을 위해 효율적인 검증 환경을 제안하였다. 검증 환경은 벡터 생성 부분, 테스트 벤치, 그리고 두개의 메모리로 구성된다. 이러한 효율적인 검증 환경을 제대로 동작시키기 위한 명령어 세트를 정의하였다. 이 명령어는 어셈블리 구조를 가지며, PCI 익스프레스의 모든 프로토콜을 지원하며, 설계된 PCI 익스프레스 컨트롤러를 검증하기 위한 모든 시나리오를 제공하도록 정의되었다. 또한 본 논문에서는 랜덤 벡터 생성 부분, 시뮬레이션 부분, 그리고 비교 엔진으로 구성된 랜덤 검증 환경을 제안하였다. 본 랜덤 테스트 검증 환경에서 수행된 결과는 일반적인 기본 동작 검증과 설계 기반 검증에서 찾지 못한 특수 경우의 에러도 발견 할 수 있다.

• 한국국방경영분석학회지
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• 제30권2호
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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.

• 인간식물환경학회지
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• 제22권6호
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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.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권5호
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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.