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My Master of Fine Art research explores the fracturing and fermentation that occurs when two cultural identities first collide, then begin to merge, one traditionally steeped in collective thinking and community – Korea, and the other with a focus on the individual and autonomy – Canada. I was trained as an artist in South Korea and learned from masters who had decades of experience in the field of traditional ceramics. Until I moved to Canada, my work focused on Korean traditional ceramics and its history. However, my desire to be recognized as an individual artist instead of another anonymous traditional ceramic artist has grown tremendously since I restarted my journey as a ceramic artist here in Canada. After practicing in the ceramics field in North America for two years, I am starting to understand what the differences are between Korea, where I received my initial education, and Canada, my adopted culture. The struggles I have experienced as an artist from outside of this new culture made me think about myself as an individual. I am now starting to discover my own unique voice in my work with clay. / October 2016

The thermoelectric properties of lanthanum-doped strontium titanate (LSTO) were investigated for high temperature applications. Ceramics with the formulation La(2x/3)Sr(1-x)TiO(3-delta) (x = 0.1, 0.3, 0.5, 0.7, 0.9) were produced using the conventional mixed oxide route. After 18 hours of milling the powders were calcined at 1373 K for 4 hours and sintered at 1733 K (± 180 K/hour) for 4 hours in air. SEM, XRD, and TEM techniques were employed to characterise the microstructure of the ceramics as well as density measurements. Subsequently the electrical conductivity, Seebeck coefficient, and thermal conductivity in order to determine the thermoelectric figure of merit of the ceramics. Key thermal conductivity results were further investigated using a computational approach. This production method resulted in high quality, high density (> 97 %) ceramics that were mostly single phase determined by XRD with a Pm3m space group, with the exception of the x = 0.9 ceramic that had a Cmmm space group. SEM imaging confirmed this finding and revealed a core-shell structure in x = 0.1 and x = 0.3 ceramics whereby the core was La-rich/Sr-deficient. Thermal conductivity of the ceramics decreased with increasing La content. This was investigated further computationally employing the Green-Kubo method. It was established that the decrease in thermal conductivity was due to phonon-scattering from A-site vacancies, and not from the stabilisation of oxygen vacancies as suggested elsewhere. The electrical properties were dramatically improved through sintering the LSTO ceramics in a 5 % H2 95 % Ar atmosphere. This led to a reduction of Ti4+ to Ti3+. The maximum electrical conductivity increased to 789 S.cm-1 resulting in a power factor of 0.0013 W.m-1 K-2 at 477 K for x = 0.3. A zT of 0.27 at 870 K for x = 0.5 was obtained due to a lower thermal conductivity. The ceramic LSTO x50H was subsequently doped with excess lanthanum; A maximum of 3 % excess was able to be fully incorporated into the lattice. This resulted in a further increase of the electrical conductivity to 875 S.cm-1 at 377 K. A decrease in the lattice thermal conductivity of ∼ 1 W.m-1 K-1 was also achieved due to the oxygen vacancies that were introduced as a result of the reducing sintering conditions. Overall a zT 0.27 at 1016 K was obtained for 3 % excess lanthanum. The ceramic LSTO x50H was also doped with niobium and vanadium. Reduction in the lattice parameter from the La substitution inhibited the niobium from fullyincorporating into the matrix. This was not the case for vanadium that resulted in an electrical conductivity of 144 S.cm-1 , Seebeck coefficient of -106 µV.K-1 , and thermal conductivity of 2.08 W.m-1 K-1 at 308 K, resulting in an overall maximum zT of 0.08 at 1070 K.

Photocatalytic membranes have been designed using two types of fine-scale alumina fibres, namely Nano Alumina Fibre (NAF) from Metallurg Engineering, Estonia and commercially available Saffil® Alumina Fibre (SAF) produced by Saffil Limited, UK. NAF fibres have an average diameter of about 15 nm and SAF about 4 μm. Membranes were produced in various ways. The fibre network architecture within the membranes, along with their porosity, specific surface area and mechanical properties, have been examined. These NAF-SAF membranes were impregnated with titania-based sol-gel coatings, to produce photocatalytic membranes. Their mechanical properties, specific surface area and flow properties were assessed and photocatalytic potential was measured by studying rates of degradation of aqueous dye solution. Membranes with photo-active top layers were designed by sedimentation of a fibrous layer of NAF-SAF, containing titania nanoparticles on a pre-sedimented support layer. Two types of photocatalyst were used, one a commercially available anatase nanopowder and the other silver-coated anatase. The latter was produced via modification of the first. Optimisation of the nanoparticle loadings was performed via assessing their photocatalytic efficiency. Specific permeability values were obtained experimentally and by prediction from the pore architecture. A novel form of photo-active membrane was designed by direct casting of milled SAF and titania-based sol-gel into circular moulds. Effects of fibre milling time and fibre to sol-gel ratio on their performance were studied, besides mechanical properties, porosity and specific surface area. Their flow properties and photocatalytic efficiency were also examined. Due to the availability of these fibres, especially the high production rates (kg/h range) and low cost of NAF, these membranes offer potential for large scale application.

Graduation date: 1997

Piezoelectric actuators have been developed in various forms ranging from discrete layered composites to functionally graded composites. These composite actuators are usually made up of differentially poled piezoelectric ceramics. This study presents analyses of thermo-electro-mechanical response of piezoelectric actuators having combinations of metal and ceramic constituents with through thickness gradual variations of the metal and ceramic compositions. This is done in order to achieve better performance. The piezoelectric ceramic constituent allows for electro-mechanical coupling response and higher resistance to elevated temperatures while the metal constituent provides more ductile composites. The gradual variation in the ceramic and metal composition helps to avoid high stress concentrations at the layer interfaces in composites. A functionally graded composite is analyzed with discrete layers of piezoelectric ceramic/metal composite. Each layer in the functionally graded composite has a fixed ceramic/metal composition. The governing equation for such a piezoelectric functionally composite beam is presented based on a multi-layer Euler-Bernoulli beam model and the overall displacement response of the beam under thermal, mechanical and electrical stimuli is predicted. The variation of this response is studied with respect to functional grading parameter, number of layers, thermal and electrical and mechanical stimuli applied. It is found that the displacement due to thermal and mechanical effects can be mitigated to some extent by the application of an electric field. It is also observed that layers of varying thickness may be assumed to model the functional grading more accurately i.e. use thinner layers where the grading changes rapidly and thicker layers where the grading changes gradually. In addition to the above parametric studies, the change in the material properties with temperature is also studied. It is found that the temperature-dependent material parameters are important when the actuators are subjected to elevated temperatures.

My ceramic sculptures are abstracted portraits of friends and family. They reveal no clues about the age, the gender, or the physical identity of the subjects. Instead, they are abstracted character traits rendered in clay with a biomorphic sensibility. I translate a particular personality trait of a friend or family member into a tangible object and arrange those pieces referencing botanical forms. I tend to choose the negative traits that cause friction in our relationship. My work is a way of acknowledging and dealing with the struggle these traits have caused. I structure my pieces as a floral arrangement to transfer an otherwise unfavorable experience into a positive one.

Antennas are designed to radiate or receive electromagnetic waves in the part of transmitting or receiving system. They are transducers which transform electric energy into waves so as to radiate radio waves, that¡¦s the primary purpose of antennae. Utilizing the characteristics of helical antennae operating in the axial mode including high directivity, broad bandwidth and circular polarization in satellite communication (ex. GPS) is detailed described in this thesis. The microwave dielectric ceramic material becomes very popular in satellite and wireless communication in recent years because of its high-K, high-Q,and stable-temperature-coefficient characteristics.Our study also utilizes its feature of high dielectric coefficient to shrink the size of the antenna significantly. In this study, we fabricate and analyze the antenna combining the advantages of the helical antenna and the microwave dielectric ceramic material.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references. Also available in electronic version. Access restricted to campus users.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: process based cost model; cost model; fuel cell; PBCM; multi-layer ceramics; sofc; solid oxide fuel cell. Includes bibliographical references.