Browsing by Author "Lin, TL"

Now showing 1 - 5 of 5

An effective approach for test-sheet composition with large-scale item banks
(2006-02-01)
Hwang, GJ
;
Lin, BMT
;
Lin, TL
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
A well-constructed test sheet not only helps the instructor evaluate the learning status of the students, but also facilitates the diagnosis of the problems embedded in the students' learning process. This paper addresses the problem of selecting proper test items to compose a test sheet that conforms to such assessment requirements as average difficulty degree, average discrimination degree, length of test time, number of test items, and specified distribution of concept weights. A mixed integer programming model is proposed to formulate the problem of selecting a set of test items that best fit the multiple assessment requirements. As the problem is a generalization of the knapsack problem, which is known to be Xg-hard in the literature, computational challenge hinders the development of efficient solution methods. Seeking approximate solutions in an acceptable time is a viable alternative. In this paper, we propose two heuristic algorithms, based upon iterative adjustment, for finding quality approximate solutions. Extensive experiments are also conducted to assess the performances of different solution methods. Statistics from a series of computational experiments indicate that our proposed algorithms can produce near-optimum combinations of the test items subject to the specified requirements in a reasonable time. (c) 2004 Elsevier Ltd. All rights reserved.
Calibrations of phase modulation amplitude of photoelastic modulator
(2004-02-01)
Wang, MW
;
Chao, YF
;
Leou, KC
;
Tsai, FH
;
Lin, TL
A multiple harmonic intensity ratio technique is proposed for calibrating the modulation amplitude (Delta(0)) of a photoelastic modulator (PEM). A data acquisition system is utilized to investigate the frequency response of this technique. Delta(0) determined by this technique is independent of frequency, which is proved using the reflection and transmission setups. In addition to confirm our calibration using the digitized oscilloscope waveform, we also obtain a set of ellipsometric parameters under various values of Delta(0) before and after calibration. We also introduce a correction factor to correct the effect caused by the shift of the modulation amplitude in the process of etching. An optical thick film is used to calibrate Delta(0) using PEM ellipsometry, and its refractive index and extinction coefficient are also obtained in etching. Finally, we suggest the use of the traces of the ellipsometric parameters under various thicknesses for monitoring instead of calculating the thickness in real time.
On the development of a computer-assisted testing system with genetic test sheet-generating approach
(2005-11-01)
Hwang, GJ
;
Lin, BMT
;
Tseng, HH
;
Lin, TL
;
資訊管理與財務金融系註：原資管所+財金所
Since the last decade, computer-assisted testing has proven to be an efficient and effective way to evaluating students' learning status such that proper tutoring strategies can be adopted to improve-their learning performance. A good test will not only help the instructor evaluate the learning status of the students, but also facilitate the diagnosis of the problems embedded in the students' learning process. One of the most important and challenging issues in conducting a good test is the construction of test sheets that can meet various assessment requirements. A previous study has indicated that selecting test items to best fit multiple assessment requirements can be formulated as a mixed integer programming model. The problem is known to be NP-hard in the literature and, hence, computational challenges hinder the development of efficient solution methods. As a sequel, we instead seek quality approximate solutions in a reasonable time. Two approximation methods based upon a genetic approach are developed. Statistics from a series of computational experiments indicate that our approach is able to efficiently generate near-optimal combinations of test items that satisfy the specified requirements or constraints.
Simulation study of carbon nanotube field emission display with under-gate and planar-gate structures
(2004-05-01)
Lan, YC
;
Lee, CT
;
Hu, Y
;
Chen, SH
;
Lee, CC
Recently, two new CNTs-based triode structures, i.e., under-gate and planar-gate structures, for field emission display were proposed and exhibited good characteristics. In this paper, we will investigate how the current density distributed on anode plate and how the display's resolution affected by the bias conditions of the emitter and the gate electrode via computer simulation. Our simulation results exhibit that the gate voltage has a strong effect on display's resolution. For the planar triode structure, the good resolution is achieved when the gate voltage is adjusted to converge the electron beams on an anode plate. For the under-gate structure, the display has a good resolution provided that the gate voltage is not too large to pull the electrons striking on other pixels. In general, the under-gate structure has a wider gate-biased operating condition, but the planar triode structure has a higher light efficiency under the same resolution. Due to the lack of field effect in the y-direction, the spot size of the current density on anode plate looks like strips instead of points. And the resolution of the display will be affected by this factor. (C) 2004 American Vacuum Society.
Synthesis of conjugated polymers by vapor deposition polymerization
(1998)
Hsu, CS
;
Lin, TL
;
應用化學系
;
Department of Applied Chemistry
The synthesis of poly(2,5-thienylene vinylene) and poly(4,7-thianaphthene) by vapor deposition polymerization is presented. 2,5-Di(bromomethyl)thiophene was subjected to vapor phase pyrolysis at 550 degrees C to form a reactive intermediate. Upon condensation, the reactive intermediate polymerized spontaneously at a temperature higher than -25 degrees C to produce poly(2,5-thienylene vinylene). The obtained poly(2,5-thienylene vinylene)s were fractionated into THF soluble and insoluble fractions. The number average molecular weights of the THF soluble fractions range from 1500 to 4000 as determined by GPC measurements. The obtained polymer shows no glass transition and melting point on the DSC scans. Doping of a poly(2,5-thienylene vinylene) film with I-2 vapor led to a conductivity of 1 x 10(-4) S cm(-1). In the second part of this study, 2,3-diethynylthiophene was subjected to vapor phase pyrolysis at 300 degrees C to yield a reactive intermediate, 4,7-dehydrothianaphthene. Upon condensation, the obtained 4,7-dehydrothianaphthenene was polymerized spontaneously at a temperature higher than -25 degrees C to produce poly(4,7-thianaphthene). The obtained poly(4,7-thianaphthene) was insoluble in common laboratory solvents and shows also no melting point and glass transition on the DSC scans.