http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/110 2026-05-17T17:01:26Z 2026-05-17T17:01:26Z Dang, Thi Thanh Thuy et al. http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/12173 2011-06-08T14:42:27Z 2009-01-01T00:00:00Z

Research, design and fabrication of a high-power combiner using Wilkinson bridge of L-band Dang, Thi Thanh Thuy; et al. In this paper, we are dealing with a L-band power combiner method using the Wilkinson bridge. This is a modern power combination technique in the microwave technology. The design and simulink of the basic power moduls and Wilkinson bridge were performed using the ADS soflware. We have researched, designed and fabricated the power combination from the basic 200W moduls. The experimental results showed that power combination method using the Wilkinson bridge may be applicable in the L-band transmission.

2009-01-01T00:00:00Z Nguyen, Van Hung Bui, Van Loat http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/12166 2011-06-08T14:39:16Z 2009-01-01T00:00:00Z

Intercomparison on internal dose assessment for $^{131}I$ Nguyen, Van Hung; Bui, Van Loat The paper resented the results of assessing internal dose for 131I by the direct method for Vietnamese objects that was issued in the Intercomparison Program of IAEA. The results on experimental measurements, calculating intake (I) of 131I to thyroid by the specilizing system for measuring thyroid activity, and committed effective dose E(50) using the specializing code of LUDEP 2.0 were shown that the results carrying out at the Nuclear Research Institute (I = 1.48.105 Bq, E (50) = 2.32 mSv) were good and were in accordance with the those of the authors in other laboratories in the world.

2009-01-01T00:00:00Z Dang, Khanh Hoi http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/12154 2011-06-08T14:33:59Z 2009-01-01T00:00:00Z

On the set of periods for periodic solusions of some linear differential equations on the multidimensional sphere $S^n$ Dang, Khanh Hoi The problem about periodic solutions for the family of linear differential equation $$ L u\equiv \left(\frac{\partial}{i\partial t} - a\Delta \right)u(x,t)=\nu G(u-f)$$ is considered on the multidimensional sphere $x \in S^n$ under the periodicity condition $u|_{t=0}=u|_{t=b}$ and $\int_{S^n}u(x,t)dx=0.$ Here $a$ is given real, $\nu$ is a fixed complex number, $ G u(x,t) $ is a linear integral operator, and $\Delta$ is the Laplace operator on $S^n.$ It is shown that the set of parameters $(\nu, b)$ for which the above problem admits a unique solution is a measurable set of full measure in ${\Bbb C}\times {\Bbb R}^+.$

2009-01-01T00:00:00Z Dinh, Van Dung http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/12144 2011-06-08T14:29:31Z 2009-01-01T00:00:00Z

Research on optimal silicon etching condition in TMAH solution and application for MEMS structure fabrication Dinh, Van Dung The research of optimal condition for etching silicon in TMAH solution with controlled etch rate and low surface roughness is the purpose of this study. The investigation on the influence of temperature, agitation, size of etch-window, etch time on etch rate and the surface roughness were carried out. With the TMAH concentration of 20% in weight, the optimal etching conditions were as follows: temperature of about 80 – 90 oC, agitation of 150 - 200 rpm. The etch rate is controlled in range of 0.49 – 0.72 $\mu$m/min. The etched surface roughness was lower than 70 nm. Development of TMAH application, a useful procedure for fabricating MEMS structures (piezoresistive accelerometer) was suggested.

2009-01-01T00:00:00Z