• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.492-497
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• 2016

The intermediate product resulting from the radical degradation experiment of PCE and the atomic charge gained through Gaussian03W were compared against each other. The result was that the ratio of PCE radical degradation was almost 98% or higher after the 9 hr point in reaction time. The reaction speed constant was $0.16hr^{-1}$ and it followed the first reaction. We could see that at each location of the PCE molecule, dechlorination happened at a point where the negative atomic charge was the greatest. Moreover, the intermediate product of PCE radical degradation that was confirmed in the experiment and literature coincided exactly with the intermediate product in the atomic charge calculation. Therefore, when the atomic charge is calculated, the radical degradation pathway of the organic chlorine compound could be forecast.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.439-444
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• 2005

Shotcrete lining is likely to be deteriorated due to the ground water which the lining is exposed to. Some tunnel collapses seemed to be affected by shotcrete degradation were reported. But there isn't any assessment method of shotcret long-term degradation. So, Experimental technology for shotcrete long-term degradation modeling was developed in this study. The shotcrete long-term degradation modeling, developed in other study in Korea Institute of Construction Technology, require the time-history of volume change. Digital strain observation system was used to acquire the time-history of volume change. To verify the Strain Observation Digital System, the measurement using the system was compared to the one using a micrometer. Through this process, The experiment for shotcrete long-term degradation modeling was set up.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.757-766
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• 2016

MTBE and other gasoline additives contained in gasoline are known to be a refractory substance resistant to biodegradation. As a method of removing these substances, a research of method using native microbes of polluted soil was progressed and among these, bio-degradation possibility under aerobic condition was evaluated. All of the experiments were progressed based on batch experiment of lab scale and analyzed by GC-FID using HS-SPME technique. The result of bio-degradation experiment based on MTBE and other additives(ETBE, TAME) was observed below 1 mg/L, which initial concentration were 100 mg/L for each method. And through production of by-product and CO2, partial mineralization was confirmed. Degradation velocity of each additive was promptly represented in the order of TBA>ETBE>MTBE>TAME. Through this study, bio-degradation possibility of native microbes of oil polluted soil, MTBE and other gasoline additives was confirmed and it was considered that the result could be used for basic experiment data in removing oil pollutants of soil.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.2
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• pp.214-219
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• 2001

In this paper, the nonlinear behavior of ultrasonic wave in partially degraded material is considered. For this aim, FDM(finite difference method) model for the nonlinear wave equation was developed with the restriction to the 1-D longitudinal wave motion and how the partial degradation in material contributes to the detected nonlinear parameter was analyzed quantitatively. In order to verify the rightness of this simulation method, the relation between the detected nonlinear parameter and the continuous distribution of degradation obtained from simulation was compared with experiment results and the simulation and experiment results showed similar tendency. It can be known from simulation result that the degree of degradation, the range of degradation and the continuous distribution of degradation have strong correlation with the detected nonlinear parameter. As it was possible in these simulations that only special part is assumed as degraded one, the quantitative evaluation of partially degraded material may be obtained by using this method.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.109-112
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• 2003

In this paper, we investigated the phosphor degradation characteristics on the ultra violet ray (UV) irradiation as well as ion bombardment. We propose a novel experiment method which is related with phosphor degradation causes. The phosphor deterioration experiments were made on the UV irradiation as well as ion bombardment. To carry out the experiment and compare the results, we made up the specific experimental setup. The results show that the deterioration by ion damage is more rigorous than that by vacuum ultra violet (VUV) on the phosphor efficiency.

• KSBB Journal
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• v.14 no.3
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• pp.315-321
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• 1999

The relationships between the explosive 2,4,6-trinitrotoluene (TNT) degradation by Stenotrophomonas maltophilia and several relevant physicochemical environmental parameters were examined. At neutral pH of the cultures, the degradation of TNT proceeded to completion, whereas only about 50% of TNT was utilized when the cultures were adjusted to acidic pH. The effect of various co-substrates (e.g., glucose, fructose, acetate, citrate, succinate) on the degradation of TNT by the test culture of S. maltophilia was evaluated. The results indicated that, among the various co-substrates studies, the test culture that received 2 mM fructose degraded 100 mg/L of TNT completely within 20 days of incubation at ambient temperature, whereas partial degradation of TNT was observed in the test culture with acetate, citrate, or succinate as a co-substrate, respectively. In fact, fructose was the best co-substrate for TNT degradation in this experiment. The effect of supplemented nitrogens [e.g., (NH$_4$)$_2$,SO$_4$, NH$_4$Cl. urea] on the TNT degradation was monitored. All supplemented nitrogens in this study were inhibitory to TNT degradation. Addition of 1% Tween80 accelerated TNT degradation, and showed complete degradation of TNT within 8 days of incubation. Addition of yeast extract resulted higher growth yields, based on turbidity measurement, but it inhibited TNT degradation.

• Journal of Welding and Joining
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• v.16 no.6
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• pp.86-96
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• 1998

This study proposes the analysis method of time series ultrasonic signal using the chaotic feature extraction for degradation extent evaluation. Features extracted from time series data using the chaotic time series signal analyze quantitatively degradation extent. For this purpose, analysis objective in this study is fractal dimension, lyapunov exponent, strange attractor on hyperspace. The lyapunov exponent is a measure of the rate at which nearby trajectories in phase space diverge. Chaotic trajectories have at least one positive lyapunov exponent. The fractal dimension appears as a metric space such as the phase space trajectory of a dynamical system. In experiment, fractal correlation) dimensions, lyapunov exponents, energy variation showed values of 2.217∼2.411, 0.097∼ 0.146, 1.601∼1.476 voltage according to degardation extent. The proposed chaotic feature extraction in this study can enhances precision ate of degradation extent evaluation from degradation extent results of the degraded materials (SA508 CL.3)

• Macromolecular Research
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• v.12 no.5
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• pp.466-473
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• 2004

We have used FT-IR spectra to explain the effects of hydrogen bonding between chitosan and polycaprolactam (PA6). A dynamic mechanical analysis study suggested that the optimum chitosan and PA6 miscibility under the conditions of this experiment were obtained at a blending ratio of 40:60. We studied the thermal degradation of chitosan blended with PA6 (chitosan/PA6) by thermogravimetric analysis and kinetic analysis (by the Ozawa method). Dry chitosan and PA6 exhibited a single stage of thermal degradation and chitosan/PA6 blends having> 20 wt% PA6 exhibited at least two stages of degradation. In chitosan/PA6 blends, chitosan underwent the first stage of thermal degradation; the second stage proceeded at a temperature lower than that of PA6, because the decomposition product of chitosan accelerated the degradation of PA6. The activation energies of the blends were between 130 and 165 kJ/mol, which are also lower than that of PA6.

• Electrical & Electronic Materials
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• v.8 no.3
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• pp.357-361
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• 1995

An experiment on characteristics of nMOSFET's in the long stress condition with the maximum of the substrate current has been carried out in order to study on the degradation due to the hot-carrier effect. Based on the measured result of the threshold voltage, the damage is mostly due to the hole injection into the oxide. After long stress, it was shown that the drain current increased at low gate voltages and hence decreased at high gate voltages.

• Journal of the Korean Magnetic Resonance Society
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• v.26 no.4
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• pp.66-70
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• 2022

Protein structure determination using NMR spectroscopy requires a suite of heteronuclear 3-D NMR experiments that can take a couple of weeks for completion. During the experiments, protein samples may suffer from slow degradation due to co-purifying proteases, which complicates and slows down the assignment procedure. Here we describe a practical protocol to avoid unwanted proteolysis during the experiment.