전류 센싱 피드백 시스템을 이용한 고안정성 산화물 TFT 쉬프트 레지스터의 설계 및 제작

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2017. 2. 정덕균.Integration of shift registers on the glass panel allows the display to be thinner, lighter, and cheaper to produce, thanks to the reduction of the number of ICs for scanning horizontal lines. Circuits of the shift register employing n-type thin film transistors (TFTs), such as hydrogenated amorphous silicon (a-Si:H) and oxide TFTs, have been reported. Recently, oxide TFTs attract much attention due to their high mobility (5~10 cm2/V∙s) compared with that of a-Si:H TFT (0.8cm2/V∙s). However, oxide TFTs often suffer from severe degradation of the threshold voltage (VTH) against the temperature and electrical stress. In this paper, in order to compensate the instability of oxide TFTs in the shift register, an oxide TFT with double gates, which can control VTH by varying the top gate bias (VTG) is adopted. The top gate of the double-gate TFT can be fabricated in the same process for the pixel IZO (Indium Zinc Oxide) so that an additional process only for the top gate is not required. Adequate VTG is provided timely, adaptively to the gate of the oxide TFTs to stabilize the threshold voltage. The fabrication result shows that the proposed shift register using VTG set at an adapted value become stable at 100℃ whereas the conventional one is mal-functioning. The optimum VTG varies from product to product and changes continuously over the lifetime of the display. Therefore, the feedback driving system suitable for the proposed shift register is required to search the optimum VTG. The system has two main functionsthe first is to sense the current of shift register and the second is the searching algorithm for finding the optimum VTG. When the transistors are degraded by an external stress, the current of the whole shift registers is changed. The information about the VTH degradation in the shift register can be gathered via current sensing circuit. The sensed current is integrated to generate the output and is forwarded to an ADC. The binary-converted current of shift register is processed by the proposed algorithm in the digital domain for obtaining an optimum VTG and then the result is converted back to analog to generate VTG. The IC implementing such functions is fabricated in a 0.18 μm BCDMOS process. When the shift register current is measured on the conventional system with increasing temperature up to 80℃, it is increased to more than 10 times than that at the room temperature. However, the proposed feedback system keeps a highly stable (<13%) current level of shift register up to 80℃ with an optimized VTG.Abstracts i Table of Contents iii List of Tables v List of Figures vi Chapter 1 Introduction 1 1.1 Background 2 1.2 Outline 7 Chapter 2 Review of oxide-based TFT device and N-type TFT circuit design 8 2.1 Overview 9 2.1.1 Characteristics of Oxide TFT 9 2.2 Oxide-based TFT 14 2.2.1 Electrical characteristics of oxide-based TFT 14 2.2.2 Stability of oxide-based TFT 18 2.3 NMOS driving circuit 24 2.3.1 Bootstrapping driving circuit 24 2.3.2 Shift register with n-type TFT 28 Chapter 3 Proposed Oxide TFT Shift Register 37 3.1 Overview 38 3.2 Characteristic of Double Gate TFT 39 3.3 Design of New shift register 46 3.3.1 Simulation Result of Conventional shift register 46 3.3.2 New shift register using Double Gate TFT 51 3.3.3 Simulation Modeling of Double Gate TFT 58 3.3.4 Simulation and Experimental Result 61 Chapter 4 Real Time Current-Sensing Feedback Compensation System 71 4.1 Overview 72 4.2 System Architecture 74 4.3 Circuit Design 77 4.3.1 Current Sensing Block 77 4.3.2 ADC/DAC Block 85 4.4 Optimum Point Searching Algorithm 100 4.5 System Verification 106 Chapter 5 Summary 116 Appendix A SPICE models 118 Bibliography 120Docto

(The) influence of children's dentofacial deformity appearence on the youth's ego identity

상담교육/석사[한글] 연구의 목적은 아동기의 이상구강형태(덧니, 부정치열, 상악전돌증, 하악전돌증, 교합장애, 안면비대칭, 악골기형, 순열 및 구개열)가 심미적으로 보기좋지 않을 뿐더러 악골이나 악관절의 발육을 저하시켜서 음식물 저작이나 말할 때 장애가 되기도 하고, 잇몸질환을 유발하며, 구강기능의 저하를 가져오는것 등으로,청년기 정서발달의 직간접적인 상관관계 원인제공 여부를 구명하여 아동기 조기구강관리의 효율성을 높히는 구강보건 자료로 쓰여지도록 하기 위함이었다. 즉, 아동기 조기 구강관리로 이상구강형태를 예방하여 청소년기 자아정체감 발달이 원만하게 잘 이루어지도록 도움들을 고려하여 포괄적인 설명을 제공하고자 하였다. 연구대상은 18세이상 24세미만의 청년들로써 정상구강형태 집단과 이상구강형태 집단 각각 250명씩 임의 표집하여 설문조사된 전체 500명의 수집된 자료를 검토한 후, 최종적으로 459명의 응답결과가 분석되었다. 연구도구로는 자아정체감을 측정하기 위해 타당도가 높은 Dignan의 'Ego Identity Scale'을 기초로 서봉연이 번안 제작한 자아정체감 척도를 사용하였다. 그리고 수집된 자료의 분석은 t-test와 일원분산분석으로 처리하고 Scheffe 검정을 실시하였다. 연구결과 청년기의 자아정체감 수준은 정상구강형태 집단에서 이상구강형태 집단보다 더 높았고, 긍정적으로 나타났다. 그리고 청년기의 자아정체감 수준은 이상구강형태에 따라, 이상형태가 심한 집단이 덜 심한 집단보다 자아정체감 수준이 낮았고 부정적으로 차이가 났다. 또한 정상구강형태 집단과 이상구강형태 집단과의 자아정체감 하위척도별 모두 정상구강형태 집단이 더 높게 나타났다. 즉, 이는 정상구강형태 집단에 비하여 이상구강형태 집단의 자아정체감은 부정적인 결과이며, 그리고 구강의 이상형태가 심할 수록 청소년기 성격형성의 주요특징인 자아정체감 형성 수준에 있어 영향을 많이 주며, 긍정적으로 수립하지 못하고 부정적이라는 점을 의미한다. 그러므로 이상구강형태가 심한 경우 그들의 치료에 대한 기대와 실망에 대하여 구체적인 감지를 하는데 자아정체감수준이 고려되어야 함이 필요하다는 것을 의미하는 것이다. [영문] The purpose of the study was to investigate the influence of children's dentofacial deformity appearance on the ego identity of youths. Children's dentofacial deformities(crowding, malocclusion, maxillary prognathism, reversed occlusion, occlusion disorders, facial hemiatrophy, jaw bones deformities, cleft lip, cleft palate, etc,.) have an influence not only from the aesthetical point of view but also on dysfunction of both jawbones and tempore-mandibular joinst, food mastication and articulation disorders, periodontal diseases, and loss of oral function. The correlation of these influences were investigated so that the data can be used for the purpose of promoting early child dental care. Subjects included in this study were 459 youths ranging in age from 18-24,including males and females. 500 questionaires were given out, and 459 answers were received and analyzed. Half of the questionaires had been given to a normal dentofacial youth group and the other half to an abnormal group. The measurement tool which was used in this study consisted of a 64 item self-report inventory which is called "Dignan's Ego Identity Scale" which was translated and adapted by Suh, Bong Yun and has a very high validity. In order to analyze the questionaire T-test, One way ANOVA and Scheffe test were used. The results of the study can be summarized as follows : The normal youth group showed a higher ego identity level than the dentofacial deformity youth group under the measurement of ego identity test. In order words, the severe dentofacial deformity youth group showed the lowest ego-identity scores while the lesser dentofacial deformity group showed lower ego-identity scores and both dentofacial deformity youth groups correlated negatively with the level of identity. The above mentioned hypothesis was partially supported at the .05 level of significance. The conclusions were drawn from the supporting evidence of the above illustrated insults. This study can be considered as one of the fundamental resources to investigate the relationship between the level of ego identity and dentofacial deformities in youth. At the same time, many kinds of testing measures have to be developed for further study.prohibitio