Effect of Pyrophyllite on the Mullite Generation in Ternary Porcelain System

Pee, J.H.,Kwak, A.N.,Kim, Jong Young,Kim, Yoo Jin,Kim, Kyung Ja Trans Tech Publications, Ltd. 2012 Key Engineering Materials Vol.512 No.-

<P>Promoting of mullite generation has been studied by replacing kaolinite with pyrophyllite because of mullite has excellent strength and thermal shock resistance. Effects of promoting of mullite generation and vitrification by replacing kaolinite with pyrophyllite on the mechanical and thermal properties were investigated. Addition of 45-55% pyrophyllite as a replacement of kaolinite (pyrophyllite (45-55%)-feldspar (30%)-clay (20%)) could vitrify samples (water absorption: 0.05%, bulk density: 2.66g/cm3) and improve the strength (122MPa) of samples fired at 1280°C. In ternary porcelain system, pyrophyllite-feldspar-clay, mullite generation of samples with 50% pyrophyllite reaches about 78.7% and thermal expansion coefficient is 5.4×10-6/K. Beyond 50% pyrophyllite addition, quartz and cristobalite phases increased. And thermal expansion coefficient of samples decreased with increasing of mullite amount.</P>

Low-Temperature Synthesis of Cordierite Using Magnesite

Pee, Jae Hwan,Kim, Geun Hee,Lee, Na Ri,Kim, Hyung Tea,Punsukumtana, Lada Trans Tech Publications, Ltd. 2014 Key Engineering Materials Vol.608 No.-

<P>Cordierite (2MgO·2Al2O3·5SiO2) has a low density of 2.2 g/cm<SUP>3</SUP> due to its high magnesium content. Because of its low thermal expansion coefficient of 1~2 x10<SUP>-6 </SUP>/<SUP>°</SUP>C, many studies are being conducted on the synthesis of cordierite with the expensive petalite as a replacement for lithium alumina silicate-based heat-resistant materials. The cordierite can be synthesized over a wide range: SiO2 at 50~70%, Al2O3 at 20~40%, and MgO at 10~30%. In this study, the range of chemical composition and temperature of cordierite synthesis is thoroughly investigated. In particular, we use natural materials (magnesite, kaolin and clay) to examine how thermal properties are affected by changes in crystal phase arising from the varying composition of MgO, SiO2 and Al2O3. We focused on factors leading to an increase in the rate of cordierite synthesis at temperatures below 1280 <SUP>°</SUP>C. From observing the synthetic rate over 1250~1280 <SUP>°</SUP>C, the sintered body at 1280 <SUP>°</SUP>C had a high synthetic rate greater than 80%. Magnesite was ball milled at constant intervals, and mean particle size was controlled to improve the synthetic rate of cordierite. As a result, the cordierite synthetic rate increased by more than 15% with decreasing the mean particle size of magnesite.</P>

Effect of Flux Materials on the Melting Characteristics of Ash Glaze

Pee, Jae Hwan,Kim, Geun Hee,Choi, You Dam,Jung, Doo Sub,Kang, Gyung In Trans Tech Publications, Ltd. 2014 Key Engineering Materials Vol.608 No.-

<P>Our objective was to make transparent glaze using oak ash which has a high content of CaO and contains P2O5. However, the melting point of oak ash is above 1340<SUP>°</SUP>C, making it difficult to make transparent glaze using only oak ash. In order to lower the melting point of oak ash, flux materials were mixed to oak ash and melting characterization was carried out. Feldspar, which is largely composed of Na2O and K2O andlimestone largely composed of CaO were used as the flux materials. The materials were added 10, 20 and 30wt%, respectively, in order to produce the glaze. Depending on the type and amount of flux materials added, the samples were fired at temperatures between 1280~1320<SUP>°</SUP>C in the reducing atmosphere. As the amount of feldspar added was increased, the melting point decreased substantially. Samples with limestone added did not melt completely even at temperatures 1300<SUP>°</SUP>C and wollastonite phase was observed in the glaze layer.</P>

Decomposition Mechanism and Decomposition Promoting Factors of Waste Hard Metal for Zinc Decomposition Process (ZDP)

Pee, J H,Kim, Y J,Kim, J Y,Seong, N E,Cho, W S,Kim, K J IOP Publishing 2011 IOP conference series. Materials science and engin Vol.18 No.20

Hydrothermal Synthesis of Rod-like Copper Oxide Crystals

Pee Jae-Hwan,Lee Dong-Wook,Kim Ung-Soo,Choi Eui-Seok 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

A hyrdrothermal synthesis has been developd to prepare rod-like crystals of copper oxide using copper nitrate trihydrate as a function of synthesis temperature, stirring speed and solution pH value. The properties of the fabricated crystals were studied using scanning electron microscopy, X-ray diffraction and particle size analysis. The morphology of the synthesized CuO was dependent on both the pH value of the solution and the morphology of the seed materials. Synthesized particles have regular morphologies and a uniform size distribution.

Direct Synthesis of Large Scale A1N Sheet

Pee, J H,Kim, Y J,Kim, C Y,Cho, W S,Kim, H T IOP Publishing 2013 IOP conference series. Materials science and engin Vol.47 No.-

Kinetics of Athermal Martensitic Transformation in Yttria Doped Zirconia

Pee, Jae-Hwan,Choi, Eui-Seok,Hayakawa, Motozo The Korean Ceramic Society 2005 한국세라믹학회지 Vol.42 No.11

The high temperature tetragonal phase of zirconia containing $1.40{\~}1.60\;mol\%$ of yttria can be fully retained at room temperature by rapid cooling. The metastable tetragonal phase transforms into the monoclinic phase athermally upon subzero cooling. The transformation exhibited an athermal burst transformation. The effects of yttria content and grain size on the athermal martensitic transformation were studied in detail. The burst temperature linearly decreased with increasing yttria content or decreasing grain size. To consider the distribution of martensite nuclei, the Weibull modulus of the athermal martensitic transformation was evaluated from the distribution of the burst transformation temperature. From the Weibull analysis, the distribution of embryos appears to be more homogeneous than that of the defects responsible for the fracture of similar material.

Preparation of lightweight porcelains using various types of pore-forming additives and their mechanical properties

PEE, Jae-Hwan,KOBAYASHI, Yuichi,KATAYAMA, Masaki,KIM, Geun-Hee,KIM, YooJin CERAMIC SOC OF JAPAN 2014 JOURNAL- CERAMIC SOCIETY JAPAN Vol.122 No.1423

Trust in User-Generated Information on Social Media during Crises: An Elaboration Likelihood Perspective

Pee, L.G.,Lee, Jung The Korea Society of Management Information System 2016 Asia Pacific Journal of Information Systems Vol.26 No.1

Social media is increasingly being used as a source of information during crises, such as natural disasters and civil unrests. However, the quality and truthfulness of user-generated information on social media have been a cause of concern. Many users find distinguishing between true and false information on social media difficult. Basing on the elaboration likelihood model and the motivation, opportunity, and ability framework, this study proposes and empirically tests a model that identifies the information processing routes through which users develop trust, as well as the factors that influence the use of these routes. The findings from a survey of Twitter users seeking information about the Fukushima Daiichi nuclear crisis indicate that individuals evaluate information quality more when the crisis information has strong personal relevance or when individuals have low anxiety about the crisis. By contrast, they rely on majority influence more when the crisis information has less personal relevance or when these individuals have high anxiety about the crisis. Prior knowledge does not have significant moderating effects on the use of information quality and majority influence in forming trust. This study extends the theorization of trust in user-generated information by focusing on the process through which users form trust. The findings also highlight the need to alleviate anxiety and manage non-victims in controlling the spread of false information on social media during crises.

A Pragmatic Concept of Good

Pee,Sei-Jin 建國大學校 人文科學硏究所 1977 인문과학논총 Vol.10 No.-

일반적으로 "좋음"은 좋음 그 자체와 "좋은 것"들로 대별된다. 그러나 "좋음"은 "좋은 것" 들을 통해서만이 그 의미가 가능하다. 마치 "노란색"은 노란 오렌지를 통해서만이 그 빛깔이 가능하듯이 "좋음"은 "좋은 것"들과의 관계를 떠나서는 정의될 수 없다. 어떤 철학자들은 인간에게 영원히 변치 않고 절대적인 "좋음"이 있다고 주장한다. 그 대표적인 것 중에 하나가 쾌락설과 자기실현설이다. 쾌락설은 쾌락만이 인간에게 진정한 "좋음"이라는 주장이다. 그러나 쾌락설은 ① 쾌락설은 객관적으로 증명될 수 있느냐 하는 문제와 ② 각 개인의 쾌락의 느낌이 다른데 누구의 쾌락이 최고의 "좋음"이냐 하는 문제와, ③ 오늘의 쾌락이 내일에도 계속 쾌락일 수 있겠는가 하는 문제를 안고 있다. 또한 자기실현설은 사람은 각기 타고난 재능으로 마땅히 추구해야 할 자기가 있으며 이 자기를 최고로 실현시키는 것이 "좋음"이라는 주장이다. 그러나 자기 실현설에서 ① 마땅히 추구해야 할 자기가 무엇인지 이를 어떻게 알수 있느냐 하는 문제와, ② 자기를 실현하는 데에는 그가 속해 있는 시대와 장소와 환경에 따라 실현될 자기가 달라질 수밖에 없는데 절대적으로 실현될 자기를 어떻게 결정하느냐 하는 문제를 안고 있다. 그러나 실용주의적 관점에서 보면 이러한 생각들은 다윈 이전의 유물이다. 이 세계에는 절대적으로 결정적인 완전한 기준은 아무 것도 없다. "좋음"이란 사람이 생각해 낸 하나의 관념일 뿐이다. 이 세상에 사람이 없다면 "좋음"과 "나쁨"의 기준이 어디에 있겠는가. 그러므로 사람과의 관계를 떠나서는 아무런 "좋음"도 어떠한 기준도 존재할 수 없다. 그런데 이 세계에는 많은 사람들이 살고 있고 그들의 인격·직업·취향·문화적 배경 등이 모두 다른데 누구의 것이 "좋음"의 기준이 되는가. 이 문제에 대해서 제임스는 그 기준을 인간생활의 실제적 결과, 즉 유용성에 둔다. 인간의 생존, 사회의 존속에 유익하고 만족을 주는 것이 진정한 "좋음"이다. 따라서 유익하지 못하고 만족을 주지 못하는 것은 "나쁨"이다.