• Fire Science and Engineering
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• v.29 no.2
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• pp.25-32
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• 2015

The improved thermal stability and anti-oxidation properties of lyocell fiber were studied based on flame retardant treatment by using $Na_3PO_4$ solution. The optimized conditions of flame retardant treatment were studied on various concentrations of $Na_3PO_4$ and the mechanism was proposed through experimental results of thermal stability and anti-oxidation. The integral procedural decomposition temperature (IPDT), limiting oxygen index (LOI) and activation energy ($E_a$) increased 30, 160% respectively via flame retardant treatment. It is noted that thermal stability and anti-oxidation improved based on char and carbon layer formation by dehydrogenation and dissociation of C-C bond resulting the hindrance of oxygen and heat energy into polymer resin. The optimized conditions for efficient flame retardant property of lyocell fiber were provided using $Na_3PO_4$ solution and the mechanism was also studied based on experimental results such as initial decomposition temperature (IDT), IPDT, LOI and $E_a$.

• Tuberculosis and Respiratory Diseases
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• v.44 no.5
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• pp.1019-1029
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• 1997

Background : Elevation of resting energy expenditure(REE) in patients with lung cancer has been described in earlier studies and may contribute to cancer cachexia, but limited information is available regarding the prevalence and determinants of the increased REE. The aim of this study was to assess the prevalence and contributing factors of a hypermetabolic state in newly detected patients with lung cancer and to assess the energy balance in order to improve our knowledge about weight loss in patients with lung cancer. Method : Thirty one consecutive, newly detected patients with lung cancer and 20 control patients with benign lung diseases were included in this study. Resting energy expenditure(REE) was measured by indirect calorimetry using ventilated hood system and predicted REE was calculated by the Harris-Benedict formular. Results : The energy balance in newly detected lung cancer patients was disturbed in a high proportion of patients, and hypermetabolic state occurred in 61% of the patients. Tumor volume, cancer type, location, stage, the presence of atelectasis or infiltration, pulmonary function, or smoking behavior were not associated with increase in REE. But patients with distant metastasis had significantly higher REE comparing with patients without metastasis. Thirty nine percents of the patients with lung cancer had substantial loss of more than 10% of their pre-illness weight. Weight losing patients with lung cancer were not accompanied by an increase in REE. Conclusion : We concluded that the REE was elevated in a higher proportion of patients with lung cancer and distant metastasis was found to be contributing factor to the elevated REE.

• Journal of Bio-Environment Control
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• v.29 no.2
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• pp.161-170
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• 2020

There is systematic spatial variations in environmental properties due to sensitive reaction to external conditions at plastic greenhouse occupied 99.2% of domestic agricultural facilities. In order to construct 3 dimensional distribution of temperature, relative humidity, CO₂ and illuminance, measurement matrix as 3 by 3 by 5 in direction of width, height and length, respectively, dividing indoor space of greenhouse was designed and tested at experimental site. Linear regression analysis was conducted to evaluate optimal estimation method in terms with horizontal and vertical variations. Even though sole measurement point for temperature and relative humidity could be feasible to assess indoor condition, multiple measurement matrix is inevitably required to improve spatial precision at certain time domain such as period of sunrise and sunset. In case with CO₂, multiple measurement matrix could not successfully improve the spatial predictability during a whole experimental period. In case with illuminance, prediction performance was getting smaller after a time period of sunrise due to systematic interference such as indoor structure. Thus, multiple sensing methodology was proposed in direction of length at higher height than growing bed, which could compensate estimation error in spatial domain. Appropriate measurement matrix could be constructed considering the transition of stability in indoor environmental properties due to external variations. As a result, optimal measurement matrix should be carefully designed considering flexibility of construction relevant with the type of property, indoor structure, the purpose of crop and the period of growth. For an instance, partial cooling and heating system to save a consumption of energy supplement could be successfully accomplished by the deployment of multiple measurement matrix.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.479-486
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• 2009

In natural environments, manganese (Mn) exists in the valence of +2, +3, and +4 and plays a pivotal role as a strong oxidant or reductant in the geochemical cycles of elements. Especially, Mn forms varying (oxyhydr)oxides. The oxidation state of structural Mn is characteristic to each oxide and is one of the most important factors controlling its geochemical behaviors such as solubility, sorption capacity, and redox potential. Therefore, it is important to elucidate processes governing Mn oxidation state in predicting the fate and transport of many redox sensitive elements in the environment. X-ray photoelectron spectroscopy (XPS) is a very useful method to determine the oxidation state of various elements in solid phases. In this study, the oxidation states of structural Mn in MnO, $Mn_2O_3$, $MnO_2$ were assessed based on the binding energy spectra of $Mn2p_{3/2}$ and Mn3s using XPS and were compared with those reported elsewhere. $Mn2p_{3/2}$ binding energies were determined as 640.9, 641.5, 641.8 eV for MnO, $Mn_2O_3$, $MnO_2$, respectively, which indicates that the binding energy increased with increasing Mn oxidation state. It was also noted that Ar etching may cause changes in electronic structure configuration on surface of the original sample.

• Journal of the Korean Chemical Society
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• v.56 no.6
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• pp.692-699
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• 2012

The aim of the present study is to explore the possibility of utilizing loess and fly ash as well as activated carbon for the adsorptive removal of PCBs in transformer oil. Here, we investigated the effect of various factors such as temperature (5, 25, 55), contact time (30 min-3 day) and adsorbent does (1, 2.5, 5, 10 g) in detail. It was found that PCBs adsorption rate from transformer oil by activated carbon is more favored than loess at the equilibrium time of 60 minutes. The equilibrium data for both activated carbon and loess is fitted well to the Freundlich isotherm model. The rate constant and activation energy of PCBs adsorption in transformer oil on each adsorbent was analyzed by fitting a kinetic model at 5, 25 and $55^{\circ}C$. From the thermodynamic parameters, the PCBs adsorption process for transformer oil/activated carbon and loess system is spontaneous and endothermic in nature.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.8
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• pp.597-604
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• 2013

A coupled thermomechanical analysis of composite structures in pyrolysis and ablation environments is performed. The pyrolysis and ablation models include the effects of mass loss, pore gas diffusion, endothermic reaction energy, surface recession, etc. The thermal and structural analysis interface is based upon a staggered coupling algorithm by using a commercial finite element code. The characteristics of the proposed method are investigated through numerical experiments with carbon/phenolic composites. The numerical studies are carried out to examine the surface recession rate by chemical and mechanical ablation. In addition, the effects of shrinkage or intumescence during the pyrolysis process are shown.

• Journal of Ginseng Research
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• v.33 no.1
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• pp.1-7
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• 2009

Clinical and animal studies have shown that free radical overload is an important cause for a variety of diseases. Although ginseng has been recognized as antioxidant, how it modulates anti-oxidative process at the molecular level remains unknown. Free radical production is induced by tumor necrosis factor-$\alpha$ (TNF-$\alpha$) under the stress condition, and (TNF-$\alpha$) release is activated by TNF-$\alpha$-converting enzyme (TACE). Since TACE inhibitor is also well known for anti-inflammatory agent, ginseng seems to show anti-oxidative activity by repressing TACE pathway. Further studies on signal transduction would be warranted to elucidate molecular action mechanisms of ginseng on anti-oxidation and anti-inflammation.

• Polymer(Korea)
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• v.25 no.6
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• pp.866-875
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• 2001

In this work, thermal decomposition mechanism based on kinetic parameters and thermal stability of carbon fiber-reinforced carbon matrix composites (C/C composites), have been studied under high temperature oxidative conditions with addition of tetra-ethylorthosilicate (TEOS) as an oxidation inhibitor. Thermogravimetric analysis (TGA) was executed to evaluate the thermal decomposition mechanism and thermal stability of C/C composites in the temperature range of 30 ～ $850^{\circ}C$. As a result, the kinetic parameters of the composites impregnated with TEOS, i.e., activation energy for thermal decomposition ($E_d$), order of reaction (n) , and pre-exponential factor (A) were evaluated as 136 kJ/mol, 0, and 2.3$\times$$10^9s^{-1}$, respectively. Especially, the IPDT and $E_d$ of C/C composites impregnated with TEOS were improved largely compared with the composites impregnated without TEOS, due to the formation of $SiO_2$ on composite surfaces, resulting in interrupting the oxygen attack to carbon active site in the composites.

• Journal of Korea Water Resources Association
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• v.51 no.8
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• pp.665-676
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• 2018

Interrill erosion on a hillslope results from the combined action of the detachment of soil particles by raindrop impact and the sediment transport of surface runoff. This study newly defined the rainfall power which detaches soil particles and the sheet-flow power contributed to sediment transport in terms of energy expenditure rate of soil erosion and presented the effective power equation for interrill erosion by rainfall-induced sheet flow. The rainfall and sheet-flow power was evaluated by factors related with rainfall, slope, and runoff and coefficients of the power equation were analyzed based on references. Futhermore it was confirmed that the relative scales between the rainfall power and the sheet-flow power according to rainfall intensity reflect on the hydrological response and physical process of interrill erosion. From application of the field data for surface runoff and soil erosion it was verified that the rainfall and sheet-flow power is an appropriate equation to estimate a interrill erosion.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.35-43
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• 1999

We propose and analyze novel optical thyristor which can be used in free-space optical interconnection(FSOI). Novel optical thyristors are fully depleted optical thyristors(DOTs) using bottom mirror and/or multiple quantum wells (MQW), thereby its switching characteristics can be improved significantly. We obtain switching characteristics using coupled junction model associated with current oriented method. Emission characteristics of the DOT are obtained using thin film characteristic matrix and van Roosbroeck-Shockley relation. Compared to the performance using conventional DOT, the optical switching energy is decreased by a factor of 0.43 and the bit-rate is increased by a factor of 1.61 when the DOT with MQW and bottom mirror is employed for FSOI.