• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.5
• /
• pp.874-882
• /
• 2001

The static and fatigue tests have been carried out to verify the validity of a generalized residual strength degradation model. And a new method of parameter determination in the model is verified experimentally to account for the effect of tension-compression fatigue loading of spheroidal graphite cast iron. It is shown that the correlation between the experimental results and the theoretical prediction on the statistical distribution of fatigue life by using the proposed method is very reasonable. Furthermore, it is found that the correlation between the theoretical prediction and the experimental results of fatigue life in case of tension-tension fatigue data in composite material appears to be reasonable. Therefore, the proposed method is more adjustable in the determination of the parameter than maximum likelihood method and minimization technique.

• Journal of Environmental Science International
• /
• v.30 no.5
• /
• pp.399-406
• /
• 2021

The dissolution of ionized gas in dielectric barrier plasma, similar to the principle of ozone generation, is a major performance-affecting factor. In this study, the plasma gas dissolving performance of a gas mixing-circulation plasma process was evaluated using an experimental design methodology. The plasma reaction is a function of four parameters [electric current (X₁), gas flow rate (X₂), liquid flow rate (X₃) and reaction time (X₄)] modeled by the Box-Behnken design. RNO (N, N-Dimethyl-4-nitrosoaniline), an indictor of OH radical formation, was evaluated using a quadratic response surface model. The model prediction equation derived for RNO degradation was shown as a second-order polynomial. By pooling the terms with poor explanatory power as error terms and performing ANOVA, results showed high significance, with an adjusted R² value of 0.9386; this indicate that the model adequately satisfies the polynomial fit. For the RNO degradation, the measured value and the predicted values by the model equation agreed relatively well. The optimum current, gas flow rate, liquid flow rate and reaction time were obtained for the highest desirability for RNO degradation at 0.21 A, 2.65 L/min, 0.75 L/min and 6.5 min, respectively.

• Journal of Applied Reliability
• /
• v.7 no.4
• /
• pp.149-162
• /
• 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.

• Journal of Korean Society for Atmospheric Environment
• /
• v.24 no.E2
• /
• pp.83-91
• /
• 2008

This work investigated the methodology to simultaneously optimize the ozone and relative humidity composition for the $NO_x$ degradation using soil biofilter. Experiments were made as a function of inlet ozone concentration ($0{\sim}1,770\;ppb$) and relative humidity ($38{\sim}81%$). Factorial design ($2^2+3$) and response surface methodology by central composite designs were used to examine the role of two factors and optimal response condition on $NO_x$ degradation. It was found that a second-order response surface model can properly interpret the experimental data with an $R^2$-value of 0.9730 and F-value of 71.83, based on which the maximum $NO_x$ degradation was predicted up to 92.8% within our experimental conditions.

• IE interfaces
• /
• v.12 no.3
• /
• pp.448-457
• /
• 1999

Accelerated degradation is concerned with models and data analyses for degradation of product performance over time at overstress and design conditions. Although there have been numerous studies with accelerated degradation theory in reliability, very few actually apply to parametric statistical analyses. This paper shows how to analyze degradation data, provides tests for how well the assumptions hold. Reel sensors, a sort of photointerrupters in home VCR, hive been tested, and least-square analyses are used to illustrate our approach. Tests for linearity of the performance-time relationship, dependence of the lognormal distribution, and the standard deviation on time are performed. The mean life of tested sensors is assessed at about 414,000 hours, and the Arrhenius activation energy of this reaction is concluded to be 0.39 eV as results.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.1
• /
• pp.77-83
• /
• 1994

Characteristics of hot-electron-induced degradation by AC, DC was investigated for p-MOSFET's(W/L=25/l$\mu$m) with sub-10nm RTP-CVD gate oxides. It was confirmed that the surface channel p-MOSFET of a thinner gate oxide shows less degradation. Mechanisms for this effect were analyzed using a simple MOS Device degradation model. It was found that the number of generated electron traps(fixed charge) is determined by the amount of peak gate current, dependent of the gate oxide thickness, and the major cause of the smaller degradation in the thinner gate oxide devices is the lower hot electron trapping carriers.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.3
• /
• pp.403-407
• /
• 2007

The anodic degradation of benzoquinone(BQ), a model compound for wastewater treatment was carried out using a home-made flow-through electrochemical cell with carbon fibers. To optimize the controlled current electrolysis condition of an aqueous BQ solution, the experimental variables affecting the degradation of BQ, such as the applying current, pH, reaction time, and flow rate of the BQ solution were examined. The degradation products of the oxidation reaction were identified by High Performance Liquid Chromatography and Inductively Coupled Plasma Atomic Emission Spectrometer. Low molecular weight aliphatic acids, and CO2 were the major products in this experiment. The removal efficiency of BQ from the solution increased with the applying current and time. 99.23% of 1.0 × 10-2 M BQ was degraded to aliphatic acids and CO2 when the applying current is 175 mA in a 12 hr electrolysis.

• Journal of Applied Reliability
• /
• v.17 no.1
• /
• pp.22-27
• /
• 2017

Purpose: The purpose of this study is to estimate the life time of OLED TV panel through electric current ADT(Accelerated Degradation Test). Methods: We performed accelerated degradation test for OLED TV Panel at the room temperature to avoid high temperature impact on the luminance. Results: we got more accurately the life time of the OLED TV when we applied ADT without temperature factor than including both current and temperature. Conclusion: Until now, the ADT of the OLED TV has been conducted with temperature and current at the same time for reducing test time and costs. We estimate incorrect life time when the temperature is adopted as an accelerated factor. Due to the high temperature impact on the luminance of the OLED TV panel. So as to solve this problem, we discard temperature and use electric current only.

• Elastomers and Composites
• /
• v.52 no.2
• /
• pp.131-135
• /
• 2017

Zinc nitrate hexahydrate [$Zn(NO_3){\cdot}6H_2O$] and sodium hydroxide [NaOH] were used as source reagents in the preparation of ZnO nanoparticles in an aqueous solution containing deionized water and ethanol in a ratio of 2:5 (v/v). ZnO nanoparticles were heated in an electric furnace at $700^{\circ}C$ for 2 h under an atmosphere of inert argon gas. The morphological and structural properties of the nanoparticles were characterized by scanning electron microscopy (SEM) and powder X-ray diffractometry (XRD). UV-vis spectrophotometry was used to analyze the photocatalytic degradation of 3-nitrophenol with ZnO nanoparticles as photocatalyst under ultraviolet irradiation at 254 nm. Evaluation of the kinetic of the photo-catalytic degradation of 3-nitrophenol indicated that the degradation of 3-nitrophenol with ZnO nanoparticles obeyed the pseudo-first order reaction rate model.

• Journal of Korean Society for Atmospheric Environment
• /
• v.17 no.E3
• /
• pp.117-124
• /
• 2001

The present paper examined the kinetics of photocatalytic degradation of volatile organic compounds (VOCs) including gaseous trichloroethylene (TCE) and acetone. In this study, we examined the effects of the initial concentration of VOCs and the light intensity of ultra-violet (UV). A batch photo-reactor was specifically designed for this work. The photocatalytic degradation rate increased with the initial concentration of VOCs but remained almost constant beyond a certain concentration. It matched well with the Langmuir-Hinshelwood (L-H) kinetic model. When the effect of light intensity was concerned, it was found that photocatalytic degradation occurs in two regimes with respect to light intensity.