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61.
Effect of Sintering Temperature on Thermoelectric Properties of p‐Bi2Te3 Alloys Produced by Gas Atomization 下载免费PDF全文
Babu Madavali Hyo‐Seob Kim Min‐Gyu Choi Gi‐Chan Park Jar‐Myung Koo Hyeon‐Taek Son Soon‐Jik Hong 《International Journal of Applied Ceramic Technology》2016,13(2):245-251
In this research, p‐type Bi2Te3–75% Sb2Te3 thermoelectric alloy powders were produced by gas atomization and subsequently sintered by hot pressing at different temperatures. The grain growth of the hot‐pressed samples was observed with increasing sintering temperature from 380°C to 460°C. The compressive strength increased with increasing hot‐pressing temperature due to the high relative density of bulk samples obtained at high temperatures. The effect of sintering temperature on thermoelectric (TE) properties was studied. The maximum power factor 3.48 mW/mK2 was obtained for the sample hot pressed at 420°C due to the resulting high electrical conductivity and enhanced Seebeck coefficient values. 相似文献
62.
Jung Hyun KimHye Young Koo You Na KoDae Soo Jung Yun Chan Kang Jong-Heun Lee 《Ceramics International》2011,37(2):687-690
Bi-based glass powders with particle size of 34 nm were prepared by high-temperature flame spray pyrolysis. The glass transition temperature (Tg) of the powders was 442 °C. Dielectric layers fired at temperatures of 480 and 500 °C contained voids, while those fired at temperatures above 540 °C had clean surfaces and no voids. The dielectric layers sintered at temperatures of 560 and 580 °C had transmittances of 70% in the visible range. Further, it was observed that the dielectric layers formed from the nanosized glass powders obtained from spray solutions containing excess boron had higher transmittances (80% in the visible range at a sintering temperature of 580 °C) than the layers formed from spray solutions containing stoichiometric amounts of boron. 相似文献
63.
Kyungtae Park Jamin Koo Dongil Shin Chang Jun Lee En Sup Yoon 《Korean Journal of Chemical Engineering》2011,28(4):1009-1018
A general mathematical programming formulation which also considers safety factors is presented for solving the multi-floor
plant layout problem. In the presence of a risk of physical explosion, the safety distance must be considered to generate
more reasonable and safe layouts. The proposed method determines detailed multi-floor process plant layouts using mixed integer
linear programming (MILP). To consider the safety distance, a consequence analysis is adopted for calculating an equipment
physical explosion probit. As the TNT equivalency method is used, more realistic estimations of equipment damage are possible,
generating safer plant layouts. The objective function minimizes the layout cost (total plant area, floor construction costs
and connection costs) and explosion damage costs for the multi-floor problem. Two illustrative examples are presented to demonstrate
the applicability of the proposed method. 相似文献
64.
Hong Gi Jin Sang Hoon Han Young Moo Lee Yeong Koo Yeo 《Korean Journal of Chemical Engineering》2011,28(1):41-48
A multi-stage model is developed for CO2 separation by hollow-fiber membrane. The model permits rapid solution of the governing differential mass and pressure distribution in hollow-fiber gas separation modules using a computational scheme that does not rely on commercial software and conventional numerical methods such as shooting techniques. For 1-stage, 2-stage and 3-stage configurations the changes of required separation areas according to stage cuts are computed. A simple model predictive control technique is employed to provide optimal operation conditions based on the proposed model. Values of stage cuts can easily be identified for various desired mole fractions and recovery rates. From the results of numerical simulations, we can see that the proposed model can be effectively used in the control of gas separation process by hollow-fiber membrane modules. 相似文献
65.
Kyung-Hoon Bang Gui-Yung Chung Hyung-Hoi Koo 《Korean Journal of Chemical Engineering》2011,28(1):272-278
The preparation of C/C composites by the chemical vapor infiltration (CVI) of the pyrolysis carbon from propane was studied. Pyrolysis carbon was deposited at 30 torr and at temperatures between 1,173 and 1,233 K. The rate of carbon deposition increased slightly with time. The main gas products in the exit gas were methane, ethylene, and acetylene. The fraction of ethylene decreased and that of acetylene increased with the reaction temperature and the propane concentration. The produced propyl radicals reacted further at a high temperature and at a high propane concentration. These trends were similar to those of the reported data. Changes of the shapes of deposited carbon in the pores of preform were confirmed with SEM photos. The mathematical modeling of the system with the deposition rate constant from the reference estimated experimental data well. 相似文献
66.
67.
In this study, nano-scale honeycomb-shaped structures with anti-reflection properties were successfully formed on SiC. The
surface of 4H-SiC wafer after a conventional photolithography process was etched by inductively coupled plasma. We demonstrate
that the reflection characteristic of the fabricated photodiodes has significantly reduced by 55% compared with the reference
devices. As a result, the optical response I
illumination/I
dark of the 4H-SiC photodiodes were enhanced up to 178%, which can be ascribed primarily to the improved light trapping in the
proposed nano-scale texturing. 相似文献
68.
A water‐developable negative photoresist based on the photocrosslinking of N‐phenylamide groups was prepared by the copolymerization of 4‐styrenesulfonic acid sodium salts (SSS) with N‐phenylmethacrylamide (copolymer A) or p‐hydroxy‐N‐phenylmethacrylamide (copolymer B), and its properties such as solubility changes, photochemical reaction, and photoresist characteristics were studied. The copolymer containing a relatively higher amount of SSS units was soluble in water. Solubility changes of the copolymers in the various buffer solutions of pH 4 ~ 11 and in water upon irradiation were observed by the measurement of insoluble fraction. The copolymers were soluble in water before irradiation, whereas they became insoluble upon irradiation with the UV light of 254 nm. The photochemical reaction of the copolymer studied by the UV and IR absorption spectroscopies indicated that a photo‐Fries rearrangement was favored for copolymer A, whereas a photocrosslinking reaction was predominate for copolymer B. Resist properties of the copolymers were studied by measurement of the normalized thickness and by development of the micropattern. Negative tone images with a resolution of 1 μm were obtained with these materials that have a sensitivity (D) of ~ 1100 mJ/cm2 with an aqueous developing process.© 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1172–1180, 2002 相似文献
69.
Neung‐Ju Lee Ja‐Chul Koo Sung‐Suk Ju Seong‐Bae Moon Won‐Jei Cho In‐Cheol Jeong Song‐Jae Lee Moo‐Youn Cho Emmanuel A Theodorakis 《Polymer International》2002,51(7):569-576
The attachment of anticancer agents to polymers is a promising approach towards reducing the toxic side‐effects and retaining the potent antitumour activity of these agents. A new tetrahydrophthalimido monomer containing 5‐fluorouracil (ETPFU) and its homopolymer and copolymers with acrylic acid (AA) and with vinyl acetate (VAc) have been synthesized and spectroscopically characterized. The ETPFU contents in poly(ETPFU‐co‐AA) and poly(ETPFU‐co‐VAc) obtained by elemental analysis were 21 mol% and 20 mol%, respectively. The average molecular weights of the polymers determined by gel permeation chromatography were as follows: Mn = 8900 g mol?1, Mw = 13 300 g mol?1, Mw/Mn = 1.5 for poly(ETPFU); Mn = 13 500 g mol?1, Mw = 16 600 g mol?1, Mw/Mn = 1.2 for poly(ETPFU‐co‐AA); Mn = 8300 g mol?1, Mw = 11 600 g mol?1, Mw/Mn = 1.4 poly(ETPFU‐co‐VAc). The in vitro cytotoxicity of the compounds against FM3A and U937 cancer cell lines increased in the following order: ETPFU > 5‐FU > poly(ETPFU) > poly(ETPFU‐co‐AA) > poly(ETPFU‐co‐VAc). The in vivo antitumour activities of all the polymers in Balb/C mice bearing the sarcoma 180 tumour cell line were greater than those of 5‐FU and monomer at the highest dose (800 mg kg?1). © 2002 Society of Chemical Industry 相似文献
70.
Mi Soon Yeo Duk Hui Kang Se Kyung Kim Hyun Shik Yun Yoon Mo Koo Youn-Woo Lee Kyung Ho Row 《Korean Journal of Chemical Engineering》2002,19(5):815-817
Ceramide was prepared by the cultivation ofSaccharomyces cerevisiae from cell extracts by solvent exfraction and analyzed by NP-HPLC using a UV detector. The mobile phase was composed of hexane,
methanol, and IPA. From the experimental conditions, the composition of mobile phase was 72/5/23 (hexane/IPA/methanol, vol%).
Quantitative analysis of ceramide was performed. Based on the analytical conditions, the effect of cultivation temperature
for the production of ceramide was investigated and the optimum cultivation temperature was found to be 35°C.
This paper is dedicated to Dr. Youn Yong Lee on the occasion of his retirement from Korea Institute of Science and Technology. 相似文献