• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.508-513
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• 2011

Hemp is known as one of the most productive and useful plants, which grows quickly in a moderate climate with only moderate water and fertilizer. Traditionally in Korea, hemp bast is used to natural fibres, and remaining such as stem and root is treated as waste. Those of hemp by-products can be transformed to bio fuel such as bio-oil and activated carbon. To understand pyrolysis characteristics, thermogravimetric analysis were carried out in TGA, in which hemp by-products were mostly decomposed at the temperature range of $270{\sim}370^{\circ}C$. The corresponding kinetic parameters including activation energy and pre-exponential factor were determined by differential method over the degree of conversions. The values of activation energies for pyrolysis were increased as the conversion increased from 10 to 90%.

• Composites Research
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• v.34 no.4
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• pp.249-256
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• 2021

In this paper, the densification of a carbon/carbon composite during a chemical vapor infiltration (CVI) process is studied using a chemo-mechanical model. The multi-physics numerical model, developed in the previous research, couples computational fluid dynamics and major chemical reactions in the reactor. The model is especially utilized to study the effect of flow behavior around the preform on the densification. Four different types of "flow-guide" structures are placed to alter the gas flow around the preform. It is shown that the flow pattern and speed around the preform can be controlled by the guide structures. The process simulations demonstrate that the average density and/or density distribution of the preform can be improved by controlling the gas flow around the perform. In this study, a full industrial-scale reactor and process parameter were used.

• Journal of Adhesion and Interface
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• v.11 no.1
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• pp.15-25
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• 2010

In the present study, isothermal stabilization processes for rayon fabrics were performed at two relatively low temperatures $180^{\circ}C$ and $200^{\circ}C$ for a long period of time. The results of weight loss, dimensional shrinkage, X-ray diffraction and scanning electron microscopic observations studied with the rayon fabrics before and after the isothermal stabilization indicated that the chemical and physical changes of rayon precursor fibers proceeded continuously and slowly at the stabilization temperature below $200^{\circ}C$. And the pre-treatment with four different chemical compounds done prior to stabilization process influenced differently the characteristics of rayon fabrics. As a result, it was noticed that under the given stabilization conditions, $H_3PO_4$ and $Na_3PO_4$ played a role in catalyzing the stabilization reaction of rayon fabric whereas $NH_4Cl$ and $ZnCl_2$ played a role in delaying or retarding the reaction. $H_3PO_4$ showed the lowest percent weight loss of the fabric in the second stabilization conducted at $350^{\circ}C$. It was considered that phosphoric acid, which has a function of flame retardant, contributed to retarding somewhat the subsequent reaction even in the second stabilization step.

• Journal of the Korean Electrochemical Society
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• v.15 no.2
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• pp.95-100
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• 2012

$LiFePO_4$ is an attractive cathode material due to its low cost, good cyclability and safety. But it has low ionic conductivity and working voltage impose a limitation on its application for commercial products. In order to solve these problems, the iron($Fe^{2+}$)site in $LiFePO_4$ can be substituted with other transition metal ions such as $Mn^{2+}$ in pursuance of increase the working voltage. Also, reducing the size of electrode materials to nanometer scale can improve the power density because of a larger electrode-electrolyte contact area and shorter diffusion lengths for Li ions in crystals. Therefore, we chose electrospinning as a general method to prepare $Li[Fe_{0.9}Mn_{0.1}]PO_4$ to increase the surface area. Also, there have been very a few reports on the synthesis of cathode materials by electrospinning method for Lithium ion batteries. The morphology and nanostructure of the obtained $Li[Fe_{0.9}Mn_{0.1}]PO_4$ nanofibers were characterized using scanning electron microscopy(SEM). X-ray diffraction(XRD) measurements were also carried out in order to determine the structure of $Li[Fe_{0.9}Mn_{0.1}]PO_4$ nanofibers. Electrochemical properties of $Li[Fe_{0.9}Mn_{0.1}]PO_4$ were investigated with charge/discharge measurements, electrochemical impedance spectroscopy measurements(EIS).

• The Korean Journal of Food And Nutrition
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• v.23 no.4
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• pp.516-525
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• 2010

Flaxseed has recently gained attention as a functional food. In this paper, physicochemical analyses of flaxseed and its oil were performed. Crude fat content ranged from 37~43%, moisture 0.2~6.8%, carbohydrate 30~35%, crude protein 18~23%, and crude ash 3~4%. Flaxseed is also an important source of dietary fiber. The TDF(total dietary fiber) contents of the flaxseed samples were 28~31%, and the SDF(souble dietary fiber) content of roasted flaxseeds was higher than that of raw flaxseeds. The major minerals found in flaxseed were calcium, potassium, magnesium, and phosphate. The flaxseeds were rich in ${\gamma}$-tocopherol with 234.3 mg/kg in raw brown flaxseed and 134.1 mg/kg in raw gold flaxseed, respectively. Roasted flaxseeds showed slightly lower vitamin and amino acid contents than those of the raw samples. The iodine, saponification, and acid values of brown flaxseed oil were 204.1 g/100 g, 193.6 mg/g, and 1.59 mg/g, and for gold flaxseed oil were 203.0 g/100 g, 189.9 mg/g, and 2.35 mg/g, respectively. ${\alpha}$-Linolenic acid(ALA, C18:3n-3) was highly concentrated in the flaxseed oil, which constituted about 55.5~56.1% of total fatty acids. Thus, flaxseed oil is a good source of omega-3 fatty acids and beneficial for the heart. Flaxseed contains high levels of dietary fiber including lignans, as well as minerals and vitamins, which may have antioxidant actions and help protect against certain cancers.

• Advances in pediatric surgery
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• v.1 no.1
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• pp.1-7
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• 1995

The acetylcholinesterase(ACHE) activity in 37 biopsies from the patients with Hirschsprung's disease was analyzed for histochemical patterns according to age, and its evolutional behavior was also assessed. The histochemical criterion used for the diagnosis of Hirschsprung's disease was that of Chow, i.e., "the presence of many coarse discrete cholinergic fibers in the muscularis mucosae and in the immediately subjacent submucosa regard less of an infiltration of cholinergic fibers in the lamina propria." The acetylcholinesterase activity in Hirschsprung's disease was further classified into 3 patterns, advocated by de Brito and Maksoud : Pattern I-many thick fibers exclusively in the muscularis mucosae and submucosa(newborn pattern). Pattern II-many thin fibers in the muscularis mucosae and submucosa with a clear infiltration of cholinergic fibers in the lamina propria(classical pattern). Pattern III-an intermediate pattern showing morphological characteristics of the two patterns with predominance of one or the other. Of 37 biopsies, Pattern 1 was seen exclusively in 16 biopsies taken from the neonates. Pattern III was 11 of 37 biopsies and it was mainly seen in children between 2 to 12 months of age. Pattern II was seen in all 3 biopsies of older than 1 year of age and in 6 ones of 3 to 12 months of age. In summary, this study reinforces the impression that there is an evolutional character of the distribution and morphology of the cholinergic ACHE positive fiber with age. In other words, ACHE activity in Hirschsprung's disease appears to evolve with age from the newborn pattern to the intermediate pattern finally to the classical pattern.

• Journal of the Korean Electrochemical Society
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• v.4 no.1
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• pp.6-9
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• 2001

[ $SiO_2$ ] effect on the electrochemical properties of polymeric gel electrolytes(PGEs) reinforced with glass fiber cloth(GFC) was investigated . PGEs were composed of polyacrylronitrile(PAN), poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)), $LiClO_4$ and three kind of plasticizer(ethylene carbonate, dietyl carbonate, propylene carbonate). $SiO_2$ was added to PGEs in the weight fraction of 10, 20, $30\%$ respectively. PGEs containing $SiO_2$ showed conductivity of over $10^{-3}S/cm\;at\;23^{\circ}C$ and electrochemical stability window to 4.8V. In the impedance spectra of the cells, which were constructed by lithium metals as electrodes, interfacial resistance increased due to growth of passivation layer during storage time and remarkable difference was not observed with content of $SiO_2$. In the impedance spectra of the lithium ion polymer batteries consisted of $LiClO_2$ and mesophase pitch-based carbon fiber(MCF), ohmic cell resistance of $SiO_2-free$ PGE was changed continuously with number of cycle, but those of $SiO_2-dispersed$ PGEs were not. Discharge capacity of the PGE containing $20wt\%\;SiO_2$ showed 132 mAh/g at 0.2C rate and $85\%$ of discharge capacity was retained at 2C rate.

• Journal of Life Science
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• v.23 no.12
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• pp.1541-1552
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• 2013

The purpose of this study was to investigate the structure and secretory function of the von Ebner's gland in parasympathetic or sympathetic nerve innervation. Sprague Dawley rats were sacrificed 3, 7, 10, 14, and 21 days after bilateral glossopharyngeal or hypoglossal nerve axotomy, respectively. The circumvallate papilla portion of the tongue was dissected and we observed morphological changes in the von Ebner's gland. The properties of glycoconjugate in the von Ebner's gland were investigated using nine biotinylated lectins (PSA, UEA I, GSL I $B_4$, ECL, DBA, SBA, HPA, SJA, or sWGA). Compared with the control group, cytoplasmic vacuoles appeared in the serous acini of the von Ebner's gland in the 3-day group, and the serous acini were significantly vacuolized and degenerated in the 10-day group after glossopharyngeal nerve axotomy. However, the structure of the von Ebner's gland did not change after hypoglossal nerve axotomy. In the control group, the von Ebner's glands secreted glycoconjugates containing ${\alpha}$-D-galactose, N-acetyl-D-galactosamine, and N-acetyl-D-glucosamine oligomer, and the amount of the secretion decreased significantly in the 10-day group after glossopharyngeal nerve axotomy. However, the amount of the glycoconjugate secretion did not change after hypoglossal nerve axotomy. Therefore, the results of this study suggest that the glossopharyngeal nerve containing parasympathetic nerve fibers is important for maintaining the structure of and secretory function in the von Ebner's gland in rats.

• Tuberculosis and Respiratory Diseases
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• v.61 no.5
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• pp.447-455
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• 2006

Background: MMPs and TIMPs are important factors for abnormal remodeling the pulmonary parenchyme in idiopathic interstitial pneumonia(IIP) This study evaluated the expression of MMPs and TIMPs in the tissue of IPF, NSIP and normal control subjects. Method: The MMP-2 and -9 activity in the lung tissue was studied by gelatin zymography, and the expression of MMP-1, -2, -9, TIMP-1 and -2 in the lung tissue was measured by immunohistochemistry. Thirty five patients, who were diagnosed with IIP (UIP ; 22, NSIP ; 13), were enrolled in the immunohistochemical study. Thirteen patients with IIP (UIP ; 9, NSIP ; 4) and five patients with lung cancer were enrolled in the zymographic assay. Results: (1) The immunohistochemistry for MMP-1,-2,-9, TIMP-1 and-2 ; MMP-1,-9 and TIMP-2 were stained stronger in the UIP subjects than NSIP and the normal control. TIMP-2 was strongly stained in the UIP tissue. particularly the fibroblasts in the fibroblastic foci. (2) Zymography for MMP-2 and MMP-9 revealed MMP-2 to have prominent expression in the UIP tissue than in the NSIP tissue. Conclusions: These results suggest that the overexpression of the TIMPs and gelatinases in UIP might be important factors in the irreversible fibrosis of the lung parenchyme.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.115-119
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• 2010

Neutral red5 (BR 5) adsorption from aqueous solution was investigated. New solid adsorbent was prepared from paper sludge incinerated at $250^{\circ}C$ during 2 hours. Experiments were carried out, in batch system, to remove RB5 dye from the synthetic waste water. Maximum adsorption of 374.98 mg/g at pH 5, at room temperature and contact time of 80 min was obtained. The Langmuir and Freundlich adsorption models were applied to interpret the equilibrium isotherm. The Freundlich isotherm fits quite well with the experimental data (with highly regression coefficient $R^2$). The incinerated sludge solid samples untreated and treated with BR5 dye were characterized by FT-IR spectrophotometer.