• 한국신뢰성학회지:신뢰성응용연구
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• 제17권2호
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• pp.103-111
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• 2017

Purpose: Accelerated degradation tests can speed time to market and reduce the test time and costs associated with long term reliability tests to verify the required service life of a product or material. This paper proposes a service life prediction method for components or materials using an accelerated degradation tests based on the relationships between temperature and the rate of failure-causing chemical reaction. Methods: The relationship between performance degradation and the rate of a failure-causing chemical reaction is assumed and least square estimation is used to estimate model parameters from the degradation model. Results: Methods of obtaining acceleration factors and predicting service life using the degradation model are presented and a numerical example is provided. Conclusion: Service life prediction of a component or material is possible at an early stage of the degradation test by using the proposed method.

• 대한기계학회논문집
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• 제17권9호
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• pp.2271-2279
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• 1993

In the case of life prediction on the structures and machines after long service, it is natural to consider a degradation problems. Most of degradation data form practical structures are isolated data obtained at the time of periodical inspection or repair. From such data, it may be difficult to obtain the degradation curve available and necessary for life prediction. In this paper, for the purpose of obtaining a degradation curves, developed the simulate degradation method and fatigue test and Charpy impact test were conducted on the degraded, simulate degraded and recovered materials. Fatigue life prediction were conducted by using the relationship between fracture transition temperature (DBTT : vTrs) obtained from the Charpy impact test through the degradation process and fatigue crack growth constants of m and C obtained from the fatigue test.

• 한국신뢰성학회지:신뢰성응용연구
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• 제9권2호
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• pp.71-80
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• 2009

This paper discusses the service life prediction methods for CFRP bar for concrete reinforcement using accelerated degradation tests. The relationship between performance degradation and the rate of a failure-causing chemical reaction is assumed for the temperature accelerated degradation tests. Methods of obtaining acceleration factors and predicting service life of the CFRP bar using the degradation model are presented.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 제2회 학술대회 논문집 일렉트렛트 및 응용기술전문연구회
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• pp.25-28
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• 2000

In this paper, the technology for accelerating degradation & life estimation on the traction motor was introduced with the stator form-winding sample coils of the 200 Class insulation system The accelerative degradation was performed in 10 cycles, which were composed of thermal stress, fast rising surge voltage, vibration, water immersion and overvoltage applying. After aging of 10 cycles, condition diagnosis test such as insulation resistance & polarization index, capacitance & dielectric loss and partial discharge properties were investigated in the temperature range of $20{\sim}160^{\circ}C$. Relationship between degradation conditions and diagnosis results were analyzed to find an dominative degradation factor at the end-life point

• 품질경영학회지
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• 제43권3호
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• pp.409-420
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• 2015

Purpose: This study is to estimate the life of elevator wire rope by using the accelerated degradation test with two accelerating variables of applied load and corrosion. Methods: Linear regression method is used to find the pseudo life of elevator wire rope at each combination of accelerating variables and the median life of elevator wire rope at use condition is estimated under the assumption that the life of elevator wire rope follows lognormal distribution. Results: The particular case study demonstrated that the results of the elevator wire life estimation by using the proposed method can provide the better solutions than existing methods. Conclusion: It can be economical to use accelerated degradation model for estimating the life of elevator wire rope.

• 한국신뢰성학회지:신뢰성응용연구
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• 제7권4호
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• pp.149-162
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• 2007

Field and accelerated tests are performed to assess the service life of construction sealants. Mathematical degradation models for tensile strength and elongation, that are the two major performance characteristics of sealants, are derived from the test results. Accelerated degradation test methods for assessing service life of construction sealants are developed based on the degrading performance and a numerical example is provided.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.115-118
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• 2000

In case of developing new motor, many examinations was tested to decide a motor efficiency and reliability. To give reliability judgment, traction motor winding insulation was tested by electrical method after appling electrical, heat, mechanical, environmental stress. In this study, stator form-wound winding of traction motor in urban transit E.M.U was tested by accelerative thermal degradation test. Stator form-wound winding was tested on the accelerative degradation composed of heat, vibration, moisture, overvoltage and researched insulation resistance, dielectric loss, partial discharge for insulation degradation properties, evaluated withstand voltage. Degradation temperature was $230[^\circ{C}]$, $250[^\circ{C}]$, $270[^\circ{C}]$, for stator form-wound winding respectively. On the test results of accelerative thermal degradation, insulation properties were relied all temperature until 10 times and expected life was evaluated by the rule of reducing $10[^\circ{C}]$ life into halves. Expected life was 31.8 years. It is guaranteed insulation reliability because of exceeding 25 years life times as considering.

• 한국신뢰성학회지:신뢰성응용연구
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• 제6권4호
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• pp.275-284
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• 2006

A test method for assessing service life of building materials and components based on performance degradation data is developed. The performance of a building material degrades as time goes by and the failure of the material is often defined as the point at which the performance of the material reaches a pre-specified degraded level. A performance-based test method is developed and a numerical example is provided to illustrate the use of the developed test method.

• Asian-Australasian Journal of Animal Sciences
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• 제24권2호
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• pp.198-205
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• 2011

This study was conducted to investigate the effect of feed types on Ochratoxin A (OTA) degradation by Korean native goats. Rumen fluid from canulated goats fed whole roughage or 50% roughage served as a source of micro-organisms. Experiments were undertaken i) to investigate OTA degradation ability in a $2{\times}4$ factorial arrangement with different feed types (100% roughage vs. 50% roughage) and rumen fluid fractions (whole rumen fluid, cells, autoclaved rumen fluid and supernatant) supplemented with OTA ii) to evaluate OTA degradation by the rumen fluid of goats fed two different diets at different time points (0, 3, 6, 9 and 12 h) of feeding iii) to isolate potential rumen microorganisms and iv) to identify elements responsible for OTA degradation. Rumen fluid from goats fed 100% roughage had higher (p<0.05) OTA degradability than 50% roughage diets. OTA degradation based on rumen fluid collection times showed that rumen fluid at 0 h showed significantly higher (p<0.05) degradability. Carboxypeptidase A (CPA) enzyme has been reported to be responsible for OTA degradation. Thus, using real time PCR, primers designed to target the CPA gene from Bacillus licheniformis could be amplified using genomic DNA from rumen fluid of goats and sequenced, thus enabling evaluation of the Bacillus population under different feeding condition and times. Our findings showed that the Bacillus population was significantly higher (p<0.05) before feeding (0 h) in animals which were fed a whole roughage diet, giving indirect evidence of OTA degradation being influenced by Bacillus sps. Thus, it can be concluded that OTA degradability is influenced by feed, feeding time and Bacillus licheniformis population.

• 한국환경농학회지
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• 제39권1호
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• pp.58-64
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• 2020

BACKGROUND: Most of the researches on the dye removal using ozonation have been focused on the removal efficiency. However, the research on their removal characteristics and mechanism according to the reaction time has been still insufficient. METHODS AND RESULTS: In this study, the effects of initial pH and dye concentration with reaction time on the degradation characteristics of methyl orange (MO) and methylene blue (MB) by ozonation were evaluated. The degradation efficiency of MB by ozonation increased with increasing pH. On the other hand, the degradation efficiency of MO by ozonation did not show a significant difference with varing pH. The both MO and MB by ozonation were decomposed within 30 min irrespective of the dye concentration, but the decomposition rates of dyes were faster at lower initial dye concentration. The decomposition efficiency of total organic carbon (TOC) in each dye solution by ozonation was low, which was found to be effective for partial decomposition such as decolorization rather than complete degradation of the dye. CONCLUSION: Overall, ozonation was an effective method for removing nondegradable dyes. However, it is necessary to study the optimization of dye degradation under various environmental conditions for ozonation.