Browsing by Author "Chang, JW"

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A synthetic approach to the secoswartzianins.
(1998-04-02)
Ho, TL
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Chang, JW
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應用化學系
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Department of Applied Chemistry
Nanometer-scale conversion of Si3N4 to SiOx
(2000-01-17)
Chien, FSS
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Chang, JW
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Lin, SW
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Chou, YC
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Chen, TT
It has been found that atomic force microscope (AFM) induced local oxidation is an effective way for converting thin (< 5 nm) Si3N4 films to SiOx. The threshold voltage for the 4.2 nm film is as low as 5 V and the initial growth rate is on the order of 10(3) nm/s at 10 V. Micro-Auger analysis of the selectively oxidized region revealed the formation of SiOx. Due to the large chemical selectivity in various etchants and great thermal oxidation rate difference between Si3N4, SiO2, and Si, AFM patterning of Si3N4 films can be a promising method for fabricating nanoscale structures. (C) 2000 American Institute of Physics. [S0003-6951(00)03003-5].
Site characterization of a dynamically compacted silty fine sand
(1998)
Huang, AB
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Chang, JW
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Chen, DDS
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Yeh, CC
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土木工程學系
A reclaimed land of approximately 2400 hectares is under construction as part of an industrial development at Mail Liao Township, on the West Coast of Taiwan. Silty fine sand dredged offshore was placed hydraulically to reach a final grade of 3 m above sea level. The foundation soil consists of similar material that extends to several hundred meters below sea level. The new sand fill and the underlying foundation soil was dynamically compacted to increase the sand density within top 10 m. Earlier attempts to estimate pile shaft frictions using CPT data according to existing methods were 30 to 70% below those measured in pile load tests at Mai Liao. A new method to predict the shaft friction that considers the characteristics of the silty fine sand at Mai Liao and the effects of dynamic compaction is proposed. The new method was developed based on a series of laboratory experiments that include CPT chamber calibration tests. According to comparisons with four pile load tests, the new method provides a reasonable and slightly conservative prediction for the shaft friction of driven PC piles. The average error was - 12%.
The behavior of a compressible silty fine sand
(1999-02-01)
Huang, AB
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Hsu, HH
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Chang, JW
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土木工程學系
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Department of Civil Engineering
Publications associated with sands are often limited to clean (i.e., little fines content), uniform, uncemented silica or quartz sand. On the other hand, the importance of mineral content, particle shapes, as well as gradation to the behavior of sand has long been recognized. Although systematic studies of sands ether than clean quartz sand have been limited, there is increasing attention being paid to sands with an appreciable fines content. Because of a major construction project, extensive field and laboratory experiments were performed on a silty fine sand from Mai-Liao, which is located on the central west coast of Taiwan. Results show that Mai-Liao Sand (MLS), a silty sand, can be significantly more compressible than clean quartz sand under static load. The particles of MLS have moderate strength, and significant crushing can be induced by triaxial shearing. As a result, MLS has low dilatancy and a relatively small range of peak friction angles. Cone penetration tests in MLS were conducted in a calibration chamber. Analyses of the data indicate that interpreting cone tip resistance in MLS using methods developed based on clean quartz sand without considering the differences of compressibility can be unrealistic. This paper documents results of the experimental studies on MLS.