• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.346-351
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• 2005

The outlet feeder pipe thinning in a PHWR (Pressurized Heavy Water Reactor) is caused by high pressure steam flow inside the pipe, which is a well known degradation mechanism called FAC (Flow Assisted Corrosion). In order to monitor the degradation, the thickness of the outlet bends closed to the exit of the pressure tube should be measured and analyzed at every official overhaul. This paper develops a mobile feeder pipe inspection robot that can minimize the irradiation dose of human workers by automating the measurement process. The robot can move by itself on the feeder pipe by using an inch worm mechanism, which is constructed by two gripper bodies that can fix the robot body on the pipe, one extendable and contractable actuator, and a rotation actuator connected the two gripper bodies to move forward and backward, and to rotate in the circumferential direction

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.2
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• pp.227-231
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• 2010

The TFRC is a congestion control mechanism which supports the requirements of video streaming applications and controls its sending rate by using the information such as loss event rate and RTT (round-trip time). However, TFRC has a performance degradation in wireless networks because it performs congestion control by judging all the losses occurred in wireless network as a congestion signal. In this paper, we propose new loss discrimination mechanism which is using ECN in order to solve the performance degradation of TFRC. Through the results of simulation, we proved that the proposed mechanism can improve the performance of TFRC.

• Bulletin of the Korean Chemical Society
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• v.11 no.2
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• pp.105-108
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• 1990

A spectroelectrochemical study on the redox chemistry of polyaniline (PANI) was carried out by using indium-tin oxide (ITO) transparent electrode in aqueous acidic solutions. Three different PANI-derived species were observed depending on the potential. The most highly oxidized species having alternating benzenoid-quinoid structures degraded through hydrolysis reaction. The degradation products were confirmed to be p-benzoquinone (BQ) and p-diaminobenzene (PDAB) by spectrophotometry anld potentiostatic experiments. Finally, a degradation mechanism is deduced from the observed behaviour.

• Journal of Microbiology and Biotechnology
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• v.28 no.2
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• pp.314-322
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• 2018

Bacillus subtilis 8 is highly efficient at degrading feather keratin. We observed integrated feather degradation over the course of 48 h in basic culture medium while studying the entire process with scanning electron microscopy. Large amounts of ammonia, sulfite, and $\text\tiny{L}$-cysteic acid were detected in the fermented liquid. In addition, four enzymes (gamma-glutamyltranspeptidase, peptidase T, serine protease, and cystathionine gamma-synthase) were identified that play an important role in this degradation pathway, all of which were verified with molecular cloning and prokaryotic expression. To the best of our knowledge, this report is the first to demonstrate that cystathionine gamma-synthase secreted by B. subtilis 8 is involved in the decomposition of feather keratin. This study provides new data characterizing the molecular mechanism of feather degradation by bacteria, as well as potential guidance for future industrial utilization of waste keratin.

• Journal of Hydrogen and New Energy
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• v.20 no.4
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• pp.317-322
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• 2009

To investigate degradation mechanism of PEMFC operated with repetitive startup/shutdown cycling, i-V characteristics, impedance, cyclic voltamograms were measured. OCV decreased from 0.967 to 0.951 V while the cell voltage at 800mA/$cm^2$ from 0.657 to 0.563V, implying that the electrodes rather than membrane electrolyte was damaged during the cycling operation. Electrochemical analyses supported that the performance degradation could be mainly attributed to degradation of the electrodes such as a decrease in electrochemical active surface area rather than degradation of membrane.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.117-120
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• 1999

The relationship between the DC degradation characteristics of the ZnO varistor and the ambient sintering-process is investigated in this study. ZnO varistors made of Matsuoka's composition were fabricated by standard ceramic techniques. The ambient sintering-process is performed at the extraordinary electrical-furnace which is equipped with the vacuum system. The Gas of sintering process was oxygen, nitrogen, argon, air respectively. The microstructure of ZnO varistors be made use of SEM equipment. The condition of DC degradation tests were conducted at $115\pm2^{\circ}C$ for periods up to 13 h. Current-voltage analysis is used to determine nonlinear coefficients($\alpha$). Resistance-frequency and capacitance-frequency analysis are accomplished to the understanding of electrical properties as DC degradation test. From above analysis, it is found that the ZnO varistor sintered in oxygen atmosphere showed superior properties at the DC degradation test.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.268-273
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• 2001

Fossil power plants operated in high temperature condition are composed of components such as turbine, boiler, and piping system. Among these components, turbine blades made with 12%Cr steel operate at a temperature above $500^{\circ}C$. Due to the long term service, turbine blades experience material degradation manifested by change in mechanical and microstructural properties. The need to make life assessment and to evaluate material degradation of turbine blade is strongly required but in reality, there is a lack of knowledge in defining failure mechanism and fundamental data for this component. Therefore, in making life assessment of turbine blade, evaluation of material degradation must be a priority. For this purpose, evaluation of toughness degradation is very important. The major cause of toughness degradation in 12Cr turbine blade is reported to be critical corrosion pitting induced by segregation of impurity elements(P etc.), coarsening of carbide, and corrosion, but the of materials for in-service application. In this study, the purpose of research is focused on evaluating toughness degradation with respect to operation time for 12%Cr steel turbine blade under high temperature steam environment and quantitatively detecting the degradation properties which is the cause of toughness degradation by means of non-destructive method, electrochemical polarization.

• Advances in environmental research
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• v.2 no.4
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• pp.261-277
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• 2013

The degradation of alachlor has been investigated using sonolysis (US), photocatalysis (UV) and sonophotocatalysis (US/UV) using three photocatalyst viz. $TiO_2$ (mixture of anatase and rutile), $TiO_2$ (anatase) and ZnO. The effect of photocatalyst loading on the extent of degradation of alachlor has been investigated by varying $TiO_2$ (both types) loading over the range of 0.01 g/L to 0.1 g/L and ZnO loading over the range of 0.05 g/L to 0.3 g/L. The optimum loading of the catalyst was found to be dependent on the type of operation i.e., photocatalysis alone or the combined operation of sonolysis and photocatalysis. All the combined processes gave complete degradation of alachlor with maximum rate of degradation being obtained in the case of sonophotocatalytic process also showing synergistic effect at optimized loading of photocatalyst. About 50% to 60% reduction in TOC has been obtained using the combined process of sonophotocatalysis depending on the operating conditions. The alachlor degradation fitted first order kinetics for all the processes under investigation. It has been observed that the $TiO_2$ (mixtrure of anatase and rutile) is the most active photocatalyst among the three photocatalysts studied in the current work. The effect of addition of radical enhancers and scavengers on sonophotocatalytic degradation of alachlor has been investigated in order to decipher the controlling mechanism. The alachlor degradation products have been identified using LC-MS method.

• The Korean Journal of Pain
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• v.36 no.1
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• pp.72-83
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• 2023

Background: Globally, spinal cord injury (SCI) results in a big burden, including 90% suffering permanent disability, and 60%-69% experiencing neuropathic pain. The main causes are oxidative stress, inflammation, and degeneration. The efficacy of the stem cell secretome is promising, but the role of human neural stem cell (HNSC)-secretome in neuropathic pain is unclear. This study evaluated how the mechanism of HNSC-secretome improves neuropathic pain and locomotor function in SCI rat models through antioxidant, anti-inflammatory, anti-matrix degradation, and neurotrophic activities. Methods: A proper experimental study investigated 15 Rattus norvegicus divided into normal, control, and treatment groups (30 µL HNSC-secretome, intrathecal in the level of T10, three days post-traumatic SCI). Twenty-eight days post-injury, specimens were collected, and matrix metalloproteinase (MMP)-9, F2-Isoprostanes, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β, and brain derived neurotrophic factor (BDNF) were analyzed. Locomotor recovery was evaluated via Basso, Beattie, and Bresnahan scores. Neuropathic pain was evaluated using the Rat Grimace Scale. Results: The HNSC-secretome could improve locomotor recovery and neuropathic pain, decrease F2-Isoprostane (antioxidant), decrease MMP-9 and TNF-α (anti-inflammatory), as well as modulate TGF-β and BDNF (neurotrophic factor). Moreover, HNSC-secretomes maintain the extracellular matrix of SCI by reducing the matrix degradation effect of MMP-9 and increasing the collagen formation effect of TGF-β as a resistor of glial scar formation. Conclusions: The present study demonstrated the mechanism of HNSC-secretome in improving neuropathic pain and locomotor function in SCI through antioxidant, anti-inflammatory, anti-matrix degradation, and neurotrophic activities.

• Journal of the Korean Professional Engineers Association
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• v.31 no.3
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• pp.17-22
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• 1998