Browsing by Author "TUNG, CH"

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Al2O3 films formed by anodic oxidation of Al-1wt.%Si-0.5wt%Cu films
(1994)
CHIU, S
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CHANG, PH
;
TUNG, CH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
AL2O3 FILMS FORMED BY ANODIC-OXIDATION OF AL-1 WEIGHT PERCENT SI-0.5 WEIGHT PERCENT CU FILMS
(1995-02-01)
CHIU, RL
;
CHANG, PH
;
TUNG, CH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The structure of the barrier-type anodic oxide formed on preannealed Al-1 weight percent (w/o) Si-0.5 w/o Cu thin film in a tartaric acid electrolyte was investigated. The oxide film is basically an amorphous layer with a thin dispersed gamma'-Al2O3 crystalline layer interposed in the center. Pores are observed to be associated with the gamma'-Al2O3 layer. Silicon nodules and Al2Cu particles originally present in the Al-1 w/o Si-0.5 w/o Cu film behave differently during anodization. Silicon nodules are oxidized to various degree during anodizing. The silica formed in the Si nodules is amorphous and somewhat porous possibly due to oxygen evolution associated with the Si anodization. A dark rim was found to surround each nodule in the anodic oxide film. This rim is shown to be thicker amorphous Al2O3 material, and its origin is attributed to the faster oxidation rate in the vicinity of Si nodules. Al2Cu precipitates are oxidized to form Al2O3 at about the same rate as the surrounding Al matrix. Copper is rejected by Al2O3 and accumulates at the Al2O3/Al interface.
INCREASING CHARACTER-RECOGNITION ACCURACY BY DETECTION AND CORRECTION OF ERRONEOUSLY IDENTIFIED CHARACTERS
(1994-09-01)
TUNG, CH
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LEE, HJ
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資訊工程學系
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Department of Computer Science
This paper presents a general approach to increasing character recognition accuracy by detection and correction of erroneously identified characters. A high-accuracy two-stage recognition system for recognizing handwritten Chinese text with 5401 categories is demonstrated. In the first stage of the system, two matching modules are applied to recognize an input character simultaneously. The first matching module uses a direction feature and the second uses a generalized feature. A character is rejected at the first stage when the matching results of the two modules are not the same. Because our first stage recognizes most of the input characters correctly and outputs a small number of candidates for each rejected character, a bigram Markov language model in the second stage can choose a candidate with high recognition rate for each rejected character according to contextual information. Experiments are performed on sentences consisting of characters extracted from the CCL/HCCR1 handwritten Chinese character database. In the first stage, the rejection rate for the input characters is 13% and the recognition rate for the accepted characters is 95.9%. In the second stage, the recognition rate for the characters rejected by the first stage is 91.2%. Thus, the overall recognition rate for the input handwritten text is 95.9% x 0.87 + 91.2% x 0.13 (= 95.2%)
MULTISTAGE PRE-CANDIDATE SELECTION IN HANDWRITTEN CHINESE CHARACTER-RECOGNITION SYSTEMS
(1994-08-01)
TUNG, CH
;
LEE, HJ
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TSAI, JY
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資訊工程學系
;
Department of Computer Science
This paper presents a model for reducing the processing time needed for recognition of handwritten Chinese characters via multi-stage pre-candidate selection. The features used in pre-candidate selection are ordered according to the reduction rates evaluated from a set of training characters. A multi-stage pre-candidate selection module is activated for each input character. In each stage, we use a single feature computed from the input character to eliminate impossible categories of characters. When the number of stages increases, the pre-candidate selection time will increase, while the candidate selection time will decrease. The total execution time will decrease when the increase in pre-candidate selection time is less than the decrease in candidate selection time. The total execution time can be predicted from the set of training characters. The number of stages of the pre-candidate selection module is selected to be that which results in the minimum total execution time. Experiments are performed on the CCL/HCCR1 database with 5401 categories of handwritten Chinese characters. The experimental results show that the proposed model can reduce the total execution time significantly without decreasing the precision of the candidate selection module.
PERFORMANCE ANALYSIS OF AN OCR SYSTEM VIA AN ARTIFICIAL HANDWRITTEN CHINESE CHARACTER GENERATOR
(1994-02-01)
TUNG, CH
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CHEN, YJ
;
LEE, HJ
;
資訊工程學系
;
Department of Computer Science
A handwritten Chinese character generator that generates handwritten Chinese characters with different variations is proposed and used to evaluate the performance of an OCR system. The character generator first generates radicals of a character stroke by stroke and then combines the generated radicals to form a line-vector character. Next, the line-vector character is thickened to obtain a character image. Characters generated by this method will have great variance in shape but will still satisfy the structural constraints. The generated characters are then used to perform two types of evaluations. First, the stability of stroke extractors in terms of stroke number is evaluated. Two stroke extractors, one based on thinning and the other on vectorization, are analyzed. The vectorization-based stroke extractor we propose operates directly on the run length codes of line segments. From experimental results, we find that the thinning-based method is more time-consuming but more stable than the vectorization-based method. Second, the peak performance of a matching module is evaluated and the recognition error caused by stroke extractors is identified.
THE EFFECT OF ANODIZING TEMPERATURE ON ANODIC OXIDE FORMED ON PURE AL THIN-FILMS
(1995-05-01)
CHIU, RL
;
CHANG, PH
;
TUNG, CH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The structure and properties of anodic Al2O3 films formed at different anodizing temperatures from thin Al films deposited by magnetron sputtering on oxidized Si wafers have been studied by transmission electron microscopy, secondary ion mass spectrometry, and electrical measurements. The anodic oxide films formed at 8 degrees C and 25 degrees C are amorphous with excellent dielectic properties, leakage current lower than 500 nA at 7.5 MV cm(-1) and no breakdown up to 7.5 MV cm(-1). Partially crystalline gamma'-Al2O3 is grown at the upper half of the 58 degrees C oxide film. This film exhibits much inferior dielectric properties than the lower temperature films. Carbon is incorporated into the top portion of the oxide films from the electrolyte during anodizing and it has little effect on the crystalline oxide formation. Oxygen penetrates into the underlying Al layer during anodizing. The penetration increases with increasing anodizing temperature.