• Fire Science and Engineering
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• v.26 no.6
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• pp.99-108
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• 2012

These days, spontaneous ignition phenomena by oxidizing heat frequently occur in the circumstances of processing and storing waste tires. Therefore, to examine the phenomena, in this work, this researcher conducted the tests of fires of fragmented waste tires (shredded tire), closely investigated components of the fire residual materials collected in the processing and storing place, and analyzed the temperature of the starting of the ignition, weight loss, and heat of reaction. For the study, this researcher conducted fire tests with fragmented waste tires in the range of 2.5 mm to 15 mm, whose heat could be easily accumulated, and performed heat analysis through DSC and TGA, DTA, DTG, and GC/MS to give scientific probability to the possibility of spontaneous ignition. According to the tests, at the 48-hour storage, rapid increase in temperature ($178^{\circ}C$), Graphite phenomenon, smoking were observed. And the result from the DTA and DTG analysis showed that at $166.15^{\circ}C$, the minimum weight loss occurred. And, the result from the test on the waste tire analysis material 1 (Unburnt) through DSC and TGA analysis revealed that at $180^{\circ}C$ or so, thermal decomposition started. As a result, the starting temperature of ignition was considered to be $160^{\circ}C$ to $180^{\circ}C$. And, at $305^{\circ}C$, 10 % of the initial weight of the material reduced, and at $416.12^{\circ}C$, 50 % of the intial weight of the material decreased. The result from the test on oxidation and self-reaction through GC/MS and DSC analysis presented that oxidized components like 1,3 cyclopentnadiene were detected a lot. But according to the result from the heat analysis test on standard materials and fragmented waste tires, their heat value was lower than the basis value so that self-reaction was not found. Therefore, to prevent spontaneous ignition by oxidizing heat of waste tires, it is necessary to convert the conventional process into Cryogenic Process that has no or few heat accumulation at the time of fragmentation. And the current storing method in which broken and fragmented materials are stored into large burlap bags (500 kg) should be changed to the method in which they are stored into small burlap bags in order to prevent heat accumulation.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.904-909
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• 2012

Acid sulfate soil (ASS) and potential acid sulfate soil (PASS) are distribution in worldwide and originate from sedimentary process, volcanic activity, or metamorphism and are problematic in agriculture and environmental due to their present and potential acidity developed by the oxidation. The PASS was defined as soil materials that had sulfidic layer more than 20 cm thick within 4 m of the soil profile and contained more than 0.15% of total-sulfur (T-S). A tentative interpretative soil classification system was proposed weak potential acid sulfate (T-S, 0.15-0.5%), moderate potential acid sulfate (T-S, 0.5-0.75%) and strong potential acid sulfate (T-S, more than 0.75%). PASS due to excess of pyrite over soil neutralizing capacity are formed. It provides no information on the kinetic rates of acid generation or neutralization; therefore, the test procedures used in acid base account (ABA) are referred to as static procedures. The net acid generation (NAG) test is a direct method to measure the ability of the sample to produce acid through sulfide oxidation and also provides and indication. The NAG test can evaluated easily whether the soils is PASS. The samples are mixed sandy loam and the PAS from the hydrothermal altered andesite (1:3, 1:8, 1:16, 1:20, 1:40, 1:80 and 1:200 ratios) in this study. We could find out that the NAG pH of the soil containing 0.75% of T-S was 2.5, and that of the soil has 0.15% of T-S was 3.8. NAG pH test can be proposed as soil classification criteria for the potential acid sulfate soils. The strong type has NAG pH of 2.5, the moderate one has NAG pH of 3.0, and the weak one has NAG pH of 3.5.

• The Korean Journal of Food And Nutrition
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• v.26 no.1
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• pp.15-21
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• 2013

This study investigated the oxidative stability of oils when dough was fried under a lower pressure than the ambient atmosphere. The pressure during the frying process was controlled at measures of 760, 560, 360 or 160 mmHg. The oil containing the dough was heated at $180^{\circ}C$ for 48 hours. Rancidity values, including acid value, peroxide value, fatty acid analysis, color changes, and browning of oil samples, were measured every 8 hours. As the frying process continued at all 4 pressure levels, the acid values (AV) increased. However, compared to the other pressure levels, the increase in AV was the least at 160 mmHg. In addition, the peroxide value at 160 mmHg was only 0.81 meq/kg compared to 1.52 meq/kg at 760 mmHg. For all pressure levels, stearic acid, oleic acid, ${\omega}$-6 linolenic acid were increased, while linoleic acid and ${\omega}$-3 linolenic acid were decreased. In terms of color, a-values representing redness were decreased, whereas b-values were increased as the frying proceeded. These results revealed that the oxidation of frying oil was decreased under reduced pressure condition. Thus, the usage of frying oil may be extended, owing to less oxidative concerns. This leads to a lower cost to the manufacturer, and furthermore, helps the environment by reducing industrial wastes.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.33-40
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• 2008

Normally, cedar heartwood has a red color. However, it frequently changes black color (blackening phenomenon). It is reported that blackening phenomenon of cedar has been caused by oxidation of phenolics and norlignan extractives under weak alkaline conditions. In this study, heat treatment and UV irradiation were carried out to reduce the difference of color value between blackened wood and bright sap wood. Effects of temperature, moisture content, treatment time and light on decrease of color difference between blackened heartwood and sapwood were evaluated in each treatment. A decrement of different color value between blackened heartwood and bright sapwood by hot-water treatment was bigger than others. An effect of the vacuum drying was similar to that of the kiln drying. UV irradiation decreases the color difference between dried blackened heartwood and bright sapwood. It is suggested that UV irradiation could be used as final treatment to reduce the color difference on wood during drying process. Determination of optimum conditions and development of hybrid process for control of discoloration will be needed in a further study.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.8
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• pp.695-700
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• 2014

In the present study, the melting temperature depression of Sn nanoparticles manufactured using the modified evaporation method was investigated. For this purpose, a modified evaporation method with mass productivity was developed. Using the manufacturing process, Sn nanoparticles of 10 nm size was manufactured in benzyl alcohol solution to prevent oxidation. To examine the morphology and size distribution of the nanonoparticles, a transmission electron microscope was used. The melting temperature of the Sn nanoparticles was measured using a Differential scanning calorimetry (DSC) which can calculate the endothermic energy during the phase changing process and an X-ray photoelectron spectroscopy (XPS) used for observing the manufactured Sn nanoparticle compound. The melting temperature of the Sn nanoparticles was observed to be $129^{\circ}C$, which is $44^{\circ}C$ lower than that of the bulk material. Finally, the melting temperature was compared with the Gibbs Thomson and Lai's equations, which can predict the melting temperature according to the particle size. Based on the experimental results, the melting temperature of the Sn nanoparticles was found to match well with those recommended by the Lai's equation.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.379-382
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• 1997

The effects of different concentrations of ${\alpha}-tocopherol,\;{\delta}-tocopherol$, BHA, BHT and TBHQ on the oxidative stability of perilla oils undergoing autoxidation during storage at $50^{\circ}C$ were studied. ${\alpha}-\;and,\;{\delta}-tocopherols$ were added as concentrations of 100, 200, 300 and 400 ppm to the perilla oils from the unroasted seeds or the roasted seeds at $190^{\circ}C$ for 20 min. BHA, BHT and TBHQ were also added to the perilla oils described above as concentrations of 50, 100, 150 and 200 ppm, respectively. The oxidative stability of perilla oils was estimated by the antioxidative index (AI: the induction periods of oils with antioxidants/the induction periods of oils without antioxidants) on the basis of the peroxide values. The roasted perilla seed oil was more stable than the unroasted seed oil in autoxidation. The addition of ${\alpha}-\;and,\;{\delta}-tocopherols$ accelerated the autoxidation of perilla oils. BHA did not show antioxidant effects, but BHT showed very weak antioxidant effects. The autoxidation of perilla oils, however, was effectively prevented by the addition of TBHQ. TBHQ showed activity in preventing 5 times on the autoxidation of perilla oils. Therefore, the oxidation stability of perilla oils seemed to be depend both on the roasting process and the kind of antioxidants.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.199-199
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• 2016

Commercially pure titanium (cp-Ti) and Ti alloys (typically Ti-6Al-4V) display excellent corrosion resistance and biocompatibility. Although the chemical composition and topography are considered important, the mechanical properties of the material and the loading conditions in the host have, conventionally. Ti and its alloys are not bioactive. Therefore, they do not chemically bond to the bone, whereas they physically bond with bone tissue. The electrochemical deposition process provides an effective surface for biocompatibility because large surface area can be served to cell proliferation. Electrochemical deposition method is an attractive technique for the deposition of hydroxyapatite (HAp). However, the adhesions of these coatings to the Ti surface needs to be improved for clinical used. Plasma electrolyte oxidation (PEO) enables control in the chemical com position, porous structure, and thickness of the $TiO_2$ layer on Ti surface. In addition, previous studies h ave concluded that the presence of $Ca^{+2}$ and ${PO_4}^{3-}$ ion coating on porous $TiO_2$ surface induced adhesion strength between HAp and Ti surface during electrochemical deposition. Silicon (Si) in particular has been found to be essential for normal bone and cartilage growth and development. Zinc (Zn) plays very important roles in bone formation and immune system regulation, and is also the most abundant trace element in bone. The objective of this work was to study electrochemical characteristcs of Zn and Si coating on Ti-6Al-4V by PEO treatment. The coating process involves two steps: 1) formation of porous $TiO_2$ on Ti-6Al-4V at high potential. A pulsed DC power supply was employed. 2) Electrochemical tests were carried out using potentiodynamic and AC impedance methoeds. The morphology, the chemical composition, and the micro-structure an alysis of the sample were examined using FE-SEM, EDS, and XRD. The enhancements of the HAp forming ability arise from $Si/Zn-TiO_2$ surface, which has formed the reduction of the Si/Zn ions. The promising results successfully demonstrate the immense potential of $Si/Zn-TiO_2$ coatings in dental and biomaterials applications.

• Membrane Journal
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• v.24 no.2
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• pp.123-135
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• 2014

The effects of pH, saturated oxygen, and back-flushing media were investigated in hybrid process of tubular ceramic microfiltration and $TiO_2$ photocatalyst-loaded PES (polyethersulfone) beads for advanced drinking water treatment, and compared results of water, nitrogen, or oxygen back-flushing in the viewpoints of membrane fouling resistance ($R_f$), permeate flux (J) and total treated water ($V_T$). $R_f$ decreased, and J and $V_T$ increased as decreasing pH. Turbidity treatment efficiencies were similar at water or nitrogen back-flushing independent of pH, but DOM (dissolved organic matter) treatment efficiency did not have a trend at water back-flushing. $R_f$ at NBF (no back-flushing) with SO (saturated oxygen) was the lower than that at NBF without SO. Also, the DOM treatment efficiency at NBF with SO was the lower than that at NBF without SO. It happened because OH radicals produced by reaction of SO and photocatalyst could dilute with water inside the module. The DOM treatment efficiency of gas back-flushing showed the larger than that of water back-flushing at back-flushig period 10 min. It proved that the adsorption or photo-oxidation of PES beads could be activated by the more effective bead-cleaning of gas back-flushing than water back-flushing.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.7
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• pp.846-851
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• 2007

This study was performed to compare and to examine the degradation efficiencies and degradation mechanism of pentachlorophenol(PCP) by UV, $UV/H_2O_2$, $Fe^{2+}$, $Fe^{2+}/H_2O_2$, and $UV/Fe^{2+}/H_2O_2$ processes. The pseudo-first order rate constant was compared in each process. The addition of $H_2O_2$ increased the rate constant by 13 times compared to the reaction with UV alone. The reaction rate in $Fe^{2+}$ reaction with PCP increased 4 times and 7.25 times by adding 180 mM $H_2O_2$ and 16 mM $H_2O_2$, respectively. Compared to that with $Fe^{2+}/H_2O_2$, the rate constant of the reaction with UV alone reaction increased 3.1 times. These results indicates the enhancement of reaction rate is closely related to the generation of OH radical. The degree of the iron sludge production observed in $Fe^{2+}/H_2O_2$ reaction was significantly reduced by irradiating UV in this process.

• The Journal of the Korea Contents Association
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• v.14 no.2
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• pp.181-191
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• 2014

In the past, making IR photography needed somewhat complicated process, so its application fields were limited. However, it has become easy to make IR photography with advanced digital technology, so it is expected that the fields of IR photography and existing limit due to difficult making process will be expanded. Therefore, in this study, it is decided that the need of IR standard chart which allows us to manage exposure and tone of IR photography for scientific purpose will increase. Two methods were used to make IR standard chart. First method is to use aluminum. When aluminum has oxide coating through anodic oxidation, it has high durability, corrosion resistance and heat resistance. Also, IR reflectance of aluminum can be controlled in some degree depending on the thickness of oxide coating. Second method is to use pigments. Yellow 10P150 pigment is used for the brightest patch. This pigment is appropriate in this study due to high heat resistance and IR reflectance. Carbon black is used for the darkest patch. Carbon black absorbs much IR, and its color is not faded by any source of light. IR reflectance is adjusted elaborately by mixing two pigments. Finally, 6 patches are selected with consideration for actual IR reflectance of patches. As a result, IR reflectance of random subjects can be known approximately and IR photographs can have appropriate contrast with the IR standard chart.