내러티브 탐구를 통한 교수 경험에 대한 성찰

염지숙,Mitton-Kukner,Jennifer,Yi Li 한국교원교육학회 2007 한국교원교육연구 Vol.24 No.2

본 연구의 목적은 각기 다른 세 가지 문화적 상황에서 가르쳤던 연구자들의 교수경험을 성찰함으로써, 그 경험이 새롭고 낯선 교수 상황에서 가르치고 있거나, 가르치게 될 교사와 교사교육자들에게 의미하는 바를 탐구하는 것이다. 이를 위해 우리는 먼저 낯선 상황에서 가르치며 혼란스럽고 불확실했던 우리의 교수경험에 대한 이야기를 공유하였다. 그리고 나서 그러한 혼란스러움과 불확실함에서 벗어나기 위해 우리가 교사로서 또는 교사교육자로서 추구했던 교수실천에 대한 이야기를 공유하였다. 교수 경험의 공유와 성찰적 대화를 통한 본 연구에서, 가르치며 배우는 일은 우리의 경험, 즉 우리의 교수를 향상시키는 것과 관련된 사고, 느낌, 행위가 포함된 경험을 통해 서서히 나타난다(Dewey, 1988)는 사실을 알게 되었다. 또한 본 연구를 통하여, 새로운 상황에서 가르치고 배우는 일과 우리의 경험에서 희망을 찾는 일은 성찰적으로 일어난다(Nunn, 2005)는 사실과 내러티브적으로 구현된 지식은 저절로 주어지는 것이 아니라 맥락 내에서의 경험과 그 경험에 대한 성찰을 통해 얻어질 수 있다(Huber, Steeves, Clandinin, & Huber, 2005)는 사실을 확인할 수 있었다.

Corrosion Resistance of Stainless Steels in Chloride Containing Supercritical Water Oxidation System

Kim, Young Sik,Mitton, D . Bryce,Latanision, Ronald M . 한국화학공학회 2000 Korean Journal of Chemical Engineering Vol.17 No.1

As the science and process applications of supercritical water (SCW) and supercritical water oxidation (SCWO) become more thoroughly understood, it is logical to envision the use of the SCWO process by diverse industries and public wastewater and sludge generators. This technology can be adapted to accomplish either pre or end-of-pipe wastewater treatment. There is a need to destroy both military and civilian hazardous waste, and urgency, mandated by public concern over traditional waste handling methodologies, to identify safe and efficient alternative technologies. By capitalizing on the properties of water above its critical point, 374℃ and 22.4 MPa for pure water, this technology provides rapid and complete oxidation with high destruction efficiencies at typical operating temperatures. Nevertheless, corrosion of the materials of fabrication is a serious concern. While iron-based alloys and nickel-based alloys are generally considered important for service applications, results from laboratory and pilot-scale SCWO systems presently in operation indicate that they will not withstand some aggressive feeds. Significant weight loss and localized effects, including stress corrosion cracking (SCC) and dealloying, are seen in chlorinated environments. This work assesses the corrosion characteristics of iron-based stainless steels exposed to high supercritical temperatures in a chlorinated military waste containing salts.

Achieving Load Awareness in Position-based Wireless Ad Hoc Routing

Xu Li,Nathalie Mitton,Amiya Nayak,Ivan Stojmenovic 한국정보기술융합학회 2012 JoC Vol.3 No.3

Influence of Chromizing Treatment on the Corrosion Behavior of AISI 316 Stainless Steel in Supercritical Water Oxidation

Kim, H.S.,Yoon, J.H.,Han, J.H.,Mitton B.D.,Latanision R.M.,Kim, Y.S. 대한금속재료학회 2004 METALS AND MATERIALS International Vol.10 No.1

SCWO, sometimes referred to as hydrothermal waste processing, uses the solvating traits of water in its supercritical condition to effectively destroy liquid organic wastes. One major problem in the supercritical water oxidation process is corrosion, because all metallic tubes in the process are exposed to high temperature and high pressure as well as severe corrosive species such as Cl^(-), F, S^(2-), and O^(2-). The presence of Cl^(-) when the pH of a solution is very low and the solution has excess oxygen causes active corrosion and metal loss by metal-chloride andor oxychloride formation. This study performed a chromizing treatment on 316 stainless steel and immersion tests in supercritical water. Weight change of chromized steels and untreated steels was measured, and the chemical state and composition of oxide films on 316 stainless steel were inves- tigated. On the basis of SCWO tests using distilled water, the oxide layer was found to be very thin and homogeneous and weight gain was observed regardless of testing temperature, while the chromizing treatment slightly reduced weight gain. In the case of SCWO tests using salt water, weight loss was observed regardless of testing temperature and its corrosion mode was pitting by chloride ion, while chromizing treatment greatly decreased the corrosion rate.

Corrosion Behavior of 316L Stainless Steel in Supercritical Water Environment

Yoon, Jae Hong,Son, K.S.,Kim, H.S.,Mitton, B.,Latanision, R.M.,Yoo, Y.R.,Kim, Young Sik Trans Tech Publications, Ltd. 2005 Materials science forum Vol.475 No.-

<P>There is a need to destroy both military and civilian hazardous waste and urgency, mandated by public concern over traditional waste handling methodologies, to safe and efficient alternative technologies. One very effective process for the destruction of such waste is supercritical water oxidation (SCWO). Nevertheless, corrosion of the materials of fabrication is a serious concern. This work intends to obtain the fundamental data for developing the corrosion resistant steel for the construction of SCWO system. The effects of various factors on the corrosion resistance of flat, welded, and U-bend 316L stainless steels in Trimsol solution were studied. Corroded product on surface was composed of multi-layer with oxides and salts, and dealloying was observed. Major corrosion phenomena of 316L stainless steel under SCWO condition were intergranular corrosion, pitting corrosion, SCC, and erosion corrosion. This work focused on the elucidation of corrosion mechanism of 316L stainless steel in SCWO environment.</P>

Biomechanical evaluation of a bioactive artificial anterior cruciate ligament

Guerard, Sandra,Manassero, Mathieu,Viateau, Veronique,Migonney, Veronique,Skalli, Wafa,Mitton, David Techno-Press 2014 Advances in biomechanics & applications Vol.1 No.4

This study aimed to assess the biomechanical performance of a new generation of artificial ligament, which can be considered "bioactive" and "biointegrated," implanted in sheep. Thirty sheep were implanted: 15 sheep received the artificial ligament grafted with a bioactive polymer (grafted) and 15 received the artificial ligament without a bioactive polymer (non-grafted). The animals were sacrificed 3 or 12 months after implantation. The knee kinematics, namely flexion-extension, anterior drawer, and varus-valgus tests, were evaluated using a fully characterized custom-made device. Afterward, the specimens were tested under uniaxial tension until failure. The flexion-extension showed significant differences between (grafted or non-grafted) artificial and native ligaments 3 months after implantation. This difference became non-significant 12 months postoperatively. The anterior tibial drawer was significantly increased 3 months after implantation and remained significantly different only for non-grafted ligament 12 months after implantation. Twelve months after implantation, the differences between grafted and non-grafted ligament biomechanical properties were significant in terms of stiffness. In terms of load to failure, grafted ligaments seem to have had slightly better performance than non-grafted ligaments 12 months postoperatively. Overall these results suggest that grafted artificial ligaments have slightly better biomechanical characteristics than non-grafted artificial ligaments 12 months after implantation in sheep.

Corrosion Behavior of 316L Stainless Steel in Supercritical Water

Yoon, SJ.H.,Kim, H.S.,Kim, Y.S.,Mitton, B.,Latanision, R.M. 국립7개대학공동논문집간행위원회 2003 공업기술연구 Vol.3 No.-

We were investigated intending to obtain the fundamental data for developing the corrosion resistant steel for the construction of SCWO (supercritical water oxidation) system. In order to match these objects, the effects of various factors on the corrosion resistance of flat specimen, welded specimen and U-bend specimen of 316L stainless steel in trimsol solution A trimsol solution of cutting oil produces a lot of Cl elements during the decomposition under supercritical condition. By the result, the corroded product of surface was composed of the composite and multi-layers that oxides or salts is mixed, and dealloying phenomena was observed in the nearest surface of 316L alloy. Main corrosion mechanism under SCWO condition is the intergranular corrosion and pitting corrosion and erosion. Initial corrosion of welded specimen that has the dendrite structure is generally progressed through the crevice of dendrite. Especially, in microstructure of the outer surface part in the U-bend specimen that maximum tensile stress is applied, some cracks with the intergranular and the intragranular corrosion with SCC were observed in the deep inside from the surface of the specimen. On the other hand, in inner side that compression stress is applied, the intergranular corrosion was only observed. The expected factors, dominating corrosion resistance of 316L alloy in supercritical water oxidation environments, are the amount of alloying elements and grain size and hardness that means resistance against erosion.

Aluminizing and Boroaluminizing Treatments of Mar-M247 and Their Effect on Hot Corrosion Resistance in Na₂SO₄-NaCl Molten Salt

Cho, J.H.,Kim, T.W.,Son, K.S.,Yoon, J.H.,Kim, H.S.,Leisk, G.G.,Mitton, D.B.,Latanision, R.M. 대한금속재료학회 2003 METALS AND MATERIALS International Vol.9 No.3

The effect of surface modifications of Mar-M247 superalloy on hot corrosion resistance was examined in Na₂SO₄-NaCl molten salt. The Mar-M247 was aluminized and boroaluminized by pack cementation in Ar and underwent a cyclic hot corrosion test in Na₂SO₄-NaCl molten salt. The XRD results showed that a Ni2Al3 phase was formed between the aluminized layer and the substrate when the surface modification temperature was below 1273 K. However, a NiAl phase formed when the temperature was above 1273 K. The intensity of the XRD peak in the NiAl phase increased after post heat treatment. Hot corrosion resistance increased for the specimens containing NiAl rather than Ni₂Al₃ phase. The ductile NiAl phase suppressed the potential for crack initiation during thermal cycling. Post heat treatment increased the corrosion resistance of the aluminized layer for Mar-M247, which underwent surface modification at 1273 K and above. In the boroaluminized Mar-M247 specimens, corrosion resistance decreased as a result of the blocking of outward diffusion of Cr by boron and decreased cohesion between the oxide scale and the aluminized layer during thermal cycling.