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  • Thesis

  • Authors: Le, Anh Tuan.;  Advisor: Know Hyug-moon (2008)

  • In the world, every building product from natural resources is a healthy indoor environment and a low environmental impact. Using natural building materials in construction can be incorporated with another structure. Moreover, using of earth products is safe, cost effective, energy efficient because the products will return to Mother Earth after using, causing almost free-spending energy to solve the problem of recycling wastes. In Korea, loess, which is named Hwangto, is known as an orange soil. It is one of the representative healthy and eco-friendly materials with the properties of high absorbency, self-purification, and radiation of infrared rays. Therefore, loess has good effectiveness for healing skin troubles such as atopic skin, pimple and eczema. The purposes to develop loe...

  • Thesis

  • Authors: Nguyễn, Vĩnh Hảo.;  Advisor: Lee, Hong-Hee; Suh, Young Soo (2008)

  • The thesis is concerned with the state estimation and control problem over the network in which an event-based sampling scheme at sensor nodes is proposed. If the network speed is high and the traffic is sparse, the traditional periodic sampling approach has many merits. But when the network bandwidth is limited due to executing tasks of several nodes, time delay becomes large and randomly varying. Therefore, to avoid these problems the sensor data transmission rate should be reduced. In the event-driven sampling scheme, sensor data are transmitted to the estimator node only if the difference between the current sensor value and the last transmitted one is greater than a given threshold. The research has shown that the event-based sampling scheme is more efficient than the periodic ...

  • Thesis

  • Authors: Lê, Văn Thăng.;  Advisor: Baptist, Robert. (2008)

  • This thesis is focussed on the chemical vapour deposition method to produce single wall carbon nanotubes.The purposes of this research are to understand exactly the role of the various chemical components presented in catalyst for the producing of SWNTs, to control process conditions, to develop synthesis techniques for SWNTs on patterned catalyst that allow the integration for electronic devices and to transfer process to industrial CVD instrument. Experimental investigations are resented which allow getting a comprehensive picture of the powder catalyst growth of carbon nanotubes film. The role of each element in catalyst and the optimal amount of them are illustrated. Based on the electron microscopy, Raman spectroscopy, X-Ray diffraction, X-Ray photoelectron spectroscopy and mic...

  • Thesis

  • Authors: Đoàn, Thế Thảo. (2008)

  • Generally, GMA (Gas Metal Arc) welding process is currently one of the most popular welding methods. To improve the welded quality and reliability as well as to increase productivity, the selection of the optimal process parameters for the robotic GMA welding process has been required as setting welding condition to archive the desired bead geometry. For this reason, it is need to know the interrelationship between the process parameters and bead geometry as welding quality. On the other hand, the welding deformations in all stages of a welding process for achieving the required precision of welded structure must be taken into account and as a result, it is required to predict the welding distortions at the early stages of welded structure design by using a simulation. Therefore,...

  • Thesis

  • Authors: Huỳnh, Kỳ Phương Hạ. (2008)

  • The Supercritical Fluid Extraction (SCFE) process is a powerful technique to develop for separating products with high added value. In this study, Supercritical fluid Carbon Dioxide (SC CO2) was used in the extraction of essential oil from two different parts of the lemongrass plant, the leaves and the stems. The batch extraction process was carried out in a stand alone compact unit of SCFE system. The lemongrass was loaded into the 500m1 extractor with an up flow rate of 0.5 m3 per hour of CO2. The extraction temperature was varied from 35°C to 50°C while the extraction pressure applied was from 90 to 110 atmospheres and the length of material was varied from 4 mm to 8 mm. The extraction time was set at 3.0 hours. This study intends to compare the composition of essential oil extra...

  • Thesis

  • Authors: Nguyen, Ngoc Tu. (2008)

  • Fault detection and diagnosis in rotating machines have been used widely in commercial systems over the past few decades. Numerous works on machine conditions have been implemented with the aid of the MCSA (Motor Current Signature Analysis) method, the vibration-based methods, etc. The purpose of these methods is to detect and diagnose faults in an early stage and therefore allow contingency plans to be put into place before the problems worsen. The dynamic and vibratory behaviours of the machine, such as vibration, sound, and temperature… are affected if the running condition is changed. The behaviours can be useful indicators to detect problems within the machine as they vary abnormally from a standard when a fault occurs. Of the many signals which can be measured, the vibration s...

  • Thesis

  • Authors: Hà, Hoàng Kha. (2008)

  • Digital filter banks have found in a wide variety of applications in data compression, digital communications, and adaptive signal processing. The common objectives of the filter bank design consist of frequency selectivity of the individual filters and perfect reconstruction of the filter banks. The design problems of filter banks are intrinsically challenging because their natural formulations are nonconvex constrained optimization problems. Therefore, there is a strong motivation to cast the design problems into convex optimization problems whose globally optimal solutions can be efficiently obtained. The main contributions of this dissertation are to exploit the convex optimization algorithms to design several classes of the filter banks. First, the two-channel orthogonal sym...