• Title/Summary/Keyword: Electronic state

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Dependence of Ferroelectric Film Formation Method on Electrical Characteristics in Solution-processed Ferroelectric Field Effect Transistor (강유전체 박막 형성방법에 따른 용액 공정 기반 강유전체 전계효과 트랜지스터의 전기적 특성 의존성)

  • Kim, Woo Young;Bae, Jin-Hyuk
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.7
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    • pp.102-108
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    • 2013
  • In manufacturing of solution-processed organic electronic devices, a spin coating method is frequently used, but which has a big problem. Solvent in a solution has a decisive effect such as physical and chemical damage for successive solution-based film deposition. Such a severe damage by solvent restricts for fabricating building blocks of multi-layered films from solutions. In this work, it will be shown that a proper combination of well-known solvents gives a chance to fabricate multi-layered film, also this new method was applied to make organic field effect transistor. Two types of bottom gate, bottom contact transistors were fabricated, one of which is fabricated by conventional single spin coating method, the other fabricated by double spin coating method. Compared with the electrical characteristics in a single spin coated transistor, the leakage current between source and gate electrode was decreased, ON state current was increased, and the extracted saturation mobility was multiplied more than 2.7 time for double spin coated transistors. It is suggested that the multiple coated gate dielectric structure is more desirable for high performance organic ferroelectric field effect transistors.

Laser crystallization in active-matrix display backplane manufacturing

  • Turk, Brandon A.;Herbst, Ludolf;Simon, Frank;Fechner, Burkhard;Paetzel, Rainer
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.1261-1262
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    • 2008
  • Laser-based crystallization techniques are ideally-suited for forming high-quality crystalline Si films on active-matrix display backplanes, because the highly-localized energy deposition allows for transformation of the as-deposited a-Si without damaging high-temperature-intolerant glass and plastic substrates. However, certain significant and non-trivial attributes must be satisfied for a particular method and implementation to be considered manufacturing-worthy. The crystallization process step must yield a Si microstructure that permits fabrication of thin-film transistors with sufficient uniformity and performance for the intended application and, the realization and implementation of the method must meet specific requirements of viability, robustness and economy in order to be accepted in mass production environments. In recent years, Low Temperature Polycrystalline Silicon (LTPS) has demonstrated its advantages through successful implementation in the application spaces that include highly-integrated active-matrix liquid-crystal displays (AMLCDs), cost competitive AMLCDs, and most recently, active-matrix organic light-emitting diode displays (AMOLEDs). In the mobile display market segment, LTPS continues to gain market share, as consumers demand mobile devices with higher display performance, longer battery life and reduced form factor. LTPS-based mobile displays have clearly demonstrated significant advantages in this regard. While the benefits of LTPS for mobile phones are well recognized, other mobile electronic applications such as portable multimedia players, tablet computers, ultra-mobile personal computers and notebook computers also stand to benefit from the performance and potential cost advantages offered by LTPS. Recently, significant efforts have been made to enable robust and cost-effective LTPS backplane manufacturing for AMOLED displays. The majority of the technical focus has been placed on ensuring the formation of extremely uniform poly-Si films. Although current commercially available AMOLED displays are aimed primarily at mobile applications, it is expected that continued development of the technology will soon lead to larger display sizes. Since LTPS backplanes are essentially required for AMOLED displays, LTPS manufacturing technology must be ready to scale the high degree of uniformity beyond the small and medium displays sizes. It is imperative for the manufacturers of LTPS crystallization equipment to ensure that the widespread adoption of the technology is not hindered by limitations of performance, uniformity or display size. In our presentation, we plan to present the state of the art in light sources and beam delivery systems used in high-volume manufacturing laser crystallization equipment. We will show that excimer-laser-based crystallization technologies are currently meeting the stringent requirements of AMOLED display fabrication, and are well positioned to meet the future demands for manufacturing these displays as well.

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Design of User Clustering and Robust Beam in 5G MIMO-NOMA System Multicell (5G MIMO-NOMA 시스템 멀티 셀에서의 사용자 클러스터링 및 강력한 빔 설계)

  • Kim, Jeong-Su;Lee, Moon-Ho
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.18 no.1
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    • pp.59-69
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    • 2018
  • In this paper, we present a robust beamforming design to tackle the weighted sum-rate maximization (WSRM) problem in a multicell multiple-input multiple-output (MIMO) - non-orthogonal multipleaccess (NOMA) downlink system for 5G wireless communications. This work consider the imperfectchannel state information (CSI) at the base station (BS) by adding uncertainties to channel estimation matrices as the worst-case model i.e., singular value uncertainty model (SVUM). With this observation, the WSRM problem is formulated subject to the transmit power constraints at the BS. The objective problem is known as on-deterministic polynomial (NP) problem which is difficult to solve. We propose an robust beam forming design which establishes on majorization minimization (MM) technique to find the optimal transmit beam forming matrix, as well as efficiently solve the objective problem. In addition, we also propose a joint user clustering and power allocation (JUCPA) algorithm in which the best user pair is selected as a cluster to attain a higher sum-rate. Extensive numerical results are provided to show that the proposed robust beamforming design together with the proposed JUCPA algorithm significantly increases the performance in term of sum-rate as compared with the existing NOMA schemes and the conventional orthogonal multiple access (OMA) scheme.

Fabric Mapping and Placement of Field Programmable Stateful Logic Array (Field Programmable Stateful Logic Array 패브릭 매핑 및 배치)

  • Kim, Kyosun
    • Journal of the Institute of Electronics and Information Engineers
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    • v.49 no.12
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    • pp.209-218
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    • 2012
  • Recently, the Field Programmable Stateful Logic Array (FPSLA) was proposed as one of the most promising system integration technologies which will extend the life of the Moore's law. This work is the first proposal of the FPSLA design automation flow, and the approaches to logic synthesis, synchronization, physical mapping, and automatic placement of the FPSLA designs. The synchronization at each gate for pipelining determines the x-coordinates of cells, and reduces the placement to 1-dimensional problems. The objective function and its gradients for the non-linear optimization of the net length and placement density have been remodeled for the reduced global placement problem. Also, a recursive algorithm has been proposed to legalize the placement by relaxing the density overflow of bipartite bin groups in a top-down hierarchical fashion. The proposed model and algorithm are implemented, and validated by applying them to the ACM/SIGDA benchmark designs. The output state of a gate in an FPSLA needs to be duplicated so that each fanout gate can be connected to a dedicated copy. This property has been taken into account by merging the duplicated nets into a hyperedge, and then, splitting the hyperedge into edges as the optimization progresses. This yields additional 18.4% of the cell count reduction in the most dense logic stage. The practicality of the FPSLA can be further enhanced primarily by incorporating into the logic synthesis the constraint to avoid the concentrated fains of gates on some logic stages. In addition, an efficient algorithm needs to be devised for the routing problem which is based on a complicated graph. The graph models the nanowire crossbar which is trimmed to be embedded into the FPSLA fabric, and therefore, asymmetric. These CAD tools can be used to evaluate the fabric efficiency during the architecture enhancement as well as automate the design.

Pre-Packing, Early Fixation, and Multi-Layer Density Analysis in Analytic Placement for FPGAs (FPGA를 위한 분석적 배치에서 사전 패킹, 조기 배치 고정 및 밀도 분석 다층화)

  • Kim, Kyosun
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.10
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    • pp.96-106
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    • 2014
  • Previous academic research on FPGA tools has relied on simple imaginary models for the targeting architecture. As the first step to overcome such restriction, the issues on analytic placement and legalization which are applied to commercial FPGAs have been brought up, and several techniques to remedy them are presented, and evaluated. First of all, the center of gravity of the placed cells may be far displaced from the center of the chip during analytic placement. A function is proposed to be added to the objective function for minimizing this displacement. And then, the density map is expanded into multiple layers to accurately calculate the density distribution for each of the cell types. Early fixation is also proposed for the memory blocks which can be placed at limited sites in small numbers. Since two flip-flops share control pins in a slice, a compatibility constraint is introduced during legalization. Pre-packing compatible flip-flops is proposed as a proactive step. The proposed techniques are implemented on the K-FPGA fabric evaluation framework in which commercial architectures can be precisely modeled, and modified for enhancement, and validated on twelve industrial strength examples. The placement results show that the proposed techniques have reduced the wire length by 22%, and the slice usage by 5% on average. This research is expected to be a development basis of the optimization CAD tools for new as well as the state-of-the-art FPGA architectures.

Dose-Dependent Associations between Wine Drinking and Breast Cancer Risk - Meta-Analysis Findings

  • Chen, Jia-Yan;Zhu, Hong-Cheng;Guo, Qing;Shu, Zheng;Bao, Xu-Hui;Sun, Feng;Qin, Qin;Yang, Xi;Zhang, Chi;Cheng, Hong-Yan;Sun, Xin-Chen
    • Asian Pacific Journal of Cancer Prevention
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    • v.17 no.3
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    • pp.1221-1233
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    • 2016
  • Purpose: To investigate any potential association between wine and breast cancer risk. Materials and Methods: We quantitatively assessed associations by conducting a meta-analysis based on evidence from observational studies. In May 2014, we performed electronic searches in PubMed, EmBase and the Cochrane Library to identify studies examining the effect of wine drinking on breast cancer incidence. The relative risk (RR) or odds ratio (OR) were used to measure any such association. Results: The analysis was further stratified by confounding factors that could influence the results. A total of twenty-six studies (eight case-control and eighteen cohort studies) involving 21,149 cases were included in our meta-analysis. Our study demonstrated that wine drinking was associated with breast cancer risk. A 36% increase in breast cancer risk was observed across overall studies based on the highest versus lowest model, with a combined RR of 1.0059 (95%CI 0.97-1.05) in dose-response analysis. However, 5 g/d ethanol from wine seemed to have protective value from our non-linear model. Conclusions: Our findings indicate that wine drinking is associated with breast cancer risk in a dose-dependent manner. High consumption of wine contributes to breast cancer risk with protection exerted by low doses. Further investigations are needed for clarification.

Predicting tobacco risk factors by using social big data (소셜 빅데이터를 활용한 담배 위험 예측)

  • Song, Tae Min;Song, Juyoung;Cheon, Mi Kyung
    • Journal of the Korean Data and Information Science Society
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    • v.26 no.5
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    • pp.1047-1059
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    • 2015
  • This study will predict risk factors associated with cigarettes in Korea by analyzing the social big data collected from the internet such as blogs, cafes, and SNSes in Korea, using data mining techniques. The key analysis results are as follows. First, when "raising cigarette price"is mentioned online, the negative group (i.e., the proportion of people holding negative views about smoking) increased from 58.6% to 74.8%, and when "lung cancer" is mentioned, it increased to 73.1%. Second, with regard to cigarettes in general, the positive group (i.e., the proportion of people holding positive views about smoking) decreased by 5.6% after the raising of cigarette prices, while the negative group increased by 6.1%. Third, when policies related to "FCTC, raising cigarette price, non-smoking laws, smoking regulations, non-smoking ads, and nonsmoking business" are more frequently mentioned online, the positive group tended to decrease. Finally, when "non-smoking drugs, non-smoking patches, and non-smoking gums" are more frequently mentioned online, the positive group tended to decrease. However, when "electronic cigarettes and supplements" are more frequently mentioned online, the positive group increased.

Development of a self-leveling system for the bucket of an agricultural front-end loader using an electro hydraulic proportional valve and a tilt sensor (전자유압 비례밸브와 경사센서를 이용한 농용 프론트 로더 버켓 능동수평유지 시스템 개발)

  • Lee, Chang Joo;Ha, Jong Woo;Choi, Deok Su;Kim, Hak Jin
    • Journal of Drive and Control
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    • v.12 no.4
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    • pp.60-70
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    • 2015
  • A front-end loader (FEL) mounted on an agricultural tractor is one of the most commonly used implements for farm work. However, when the tractor carries material using the bucket attached to the FEL on a sloping ground, the materials can spill or roll back over the operator due to the tilted body, thereby requiring the bucket surface to remain level at a constant value regardless of varying slopes. In this study, an active system for controlling the angle of the FEL bucket on a tractor based on the real-time measurement of ground slopes was developed to enable the bucket to constantly remain level. A FEL simulator operated based on an electro hydraulic proportional valve (EHPV) was constructed in the laboratory to develop a proportional-integral-derivative (PID) controller forming a virtual electronic control unit (ECU) on the computer, which could automatically adjust the bucket angles depending on varying input angles while sending SAE-J1939 associated messages via CAN BUS to the EHPV. The different parameter values for the PID controller due to the gravity effect of the bucket were determined using a manual PID tuning method while assuming that the tractor travels on either an ascending slope or a descending slope. The developed PID control-based self-leveling system showed a mean of steady-state errors of within $1^{\circ}$ and a mean of delayed times of ~ 0.8s when the step input of $+20^{\circ}$ was given, implying that the developed system and control algorithm would be effective in maintaining the bucket angle at a certain value. Future studies include the improvement of the control algorithm to reduce such a time delay as well as the application of the developed algorithm to the FEL mounted on a tractor tested at a testing ground.

The Question of 'State and Art' with regard to Soviet Socialist Realism (소련 사회주의 리얼리즘에 관하여: '국민과 예술'의 문제)

  • Alexander, Morozov
    • The Journal of Art Theory & Practice
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    • no.7
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    • pp.125-163
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    • 2009
  • The artworks of Socialist Realism of the former Soviet Union, with the beginning of the 21st century, are gaining a new attention from art collectors. One reason for this might consist in the fact that relevant art pieces exemplify the ways in which they visualize ideas on the basis of their high-profile art tradition and also in which they integrate their utopian ideals with mysticism. These aspects of the Soviet art goes far beyond the wide-spread assumption that their art, as a means of propaganda, principally represents a political allegiance to the system. With Stalin coming into power in the 1930s, the artistic trend of Socialist Realism obtained a nationwide sympathy and support from people, giving birth to a new art which essentially corresponded to the demands of the political power. An official art current of the USSR over the period from the 1930s to 1950s, Socialist Realism was in tandem with the Communist commitment to the party and popularity, symbolizing a loyalty to the cause. It was thus characterized by plainness and lucidity so that ordinary people could gain easy access to art. Its salient feature, over an entire range of art, was an optimistic pursuit of a utopian dream. Therefore, it tallied with the popular sentiment for a Communist paradise, giving form to their beliefs in human agency working at the materialist world and also to such abstract concepts as force, fitness, and beauty by adding even mythical ideals. Its main subject matter includes harvest feasts of collective farms, imaginary socialist cities, grand marches of heroic laborers and in this way it served as a propaganda for a sacred utopia of socialist totalitarianism. On the other end of the spectrum, however, rose the second camp of art, which put an emphasis on bona-fide artistic activities of plastic art and on an artist's personal expression and freedom, as opposed to the surface optimism of Socialist Realism. Central to the Russian Avant Garde art, which prized the above-mentioned values, were Malevich's Geometric Abstraction and A. Rodchenko's Constructivism. Furthermore, in the transitional era of the late 20th century and the 21st century it was recognized that film art or electronic media art, rather than traditional genre of paintings, would function as a more efficient way of propaganda. These new genres were made possible by ridiculing the stereotypes of the Russian lifestyle and also by ignoring ethical or professional dimensions of artworks. That is, they reinvented themselves into a sort of field art, seemingly degrading the quality of artworks and transforming them into artifacts or simulacres in the very sense of post-modernism. The advent of the new era brought about the formation and occupation of pop culture of the younger generations, calling into question the idea of art as the class-determined. It also increased the attention to field art, which extensively found way to modern art centers, galleries, and exhibition projects. It can be stated that this was a natural outcome of human nature.

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ZnTe 완충층 두께에 따른 CdTe/ZnTe 양자점의 운반자 동역학

  • Kim, Su-Hwan;Lee, Ju-Hyeong;Choe, Jin-Cheol;Lee, Hong-Seok
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.305-305
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    • 2014
  • 양자점(Quantum dots)은 3차원적 운반자 구속과 낮은 전류와 높은 온도에서 작동하는 나노 크기의 전기적, 광학적 소자로 응용이 적합하기 때문에 그 특성을 이용한 단전자 트랜지스터, 적외선 검출기, 레이저, LED, 태양전지 등 반도체 소자로의 응용연구가 활발히 진행되고 있다. 특히 양자점의 낮은 임계전류밀도와 높은 차동 이득(differential gain), 그리고 고온에서 작동이 용이하여 양자점 레이저로 활용되고 있다. 이러한 분야에 양자점을 응용하기 위해서는 양자점의 운반자 동역학을 이해하고 양자점의 모양, 크기, 크기 분포와 같은 특성 조절이 필요하다. 또한 기존의 연구들은 III-V족 화합물 반도체 양자점에 대한 연구가 대부분이며, II-VI족으로 구성된 연구가 미흡한 상황이기 때문에 II-VI족 화합물 반도체 양자점에 대한 많은 연구가 필요한 상황이다. II-VI 족 화합물 반도체 양자점은 기존의 III-V 족 양자점보다 더 큰 엑시톤 결합에너지(exciton binding energy)를 가지고 있으며, 이러한 특성을 가지는 II-VI 족 화합물 반도체 양자점 중에서도 CdTe 양자점은 높은 엑시톤 결합에너지와 녹색 스펙트럼 영역을 필요로 하는 광학적 장치들에 응용 가능성이 높기 때문에 더욱 주목받고 있다. 본 연구에서는 분자 선속 에피 성장법(Molecular Beam Epitaxy; MBE)과 원자 층 교대 성장법(Atomic Layer Epitaxy; ALE)으로 CdTe/ZnTe 나노구조에서 ZnTe 완충층의 두께에 따른 운반자 동역학 및 광학적 특성을 연구 하였다. 저온 광루미네센스 측정(Photoluminescence; PL) 을 통하여 ZnTe 완충층 두께가 증가할수록 양자점의 광루미네센스 피크가 낮은 에너지로 이동함을 알 수 있었는데, 이는 ZnTe 완충층의 두께가 증가할수록 ZnTe 완충층과 CdTe 양자점의 격자 불일치(lattice mismatch)로 인한 구조 변형력이 감소하고 이에 따라 CdTe 양자점으로 가해지는 변형(Strain)이 감소하여 CdTe 양자점의 크기가 증가했기 때문이다. 그리고 ZnTe 완충층의 두께가 증가할수록 PL 세기가 증가함을 알 수 있었는데, 이는 ZnTe 완충층의 두께가 증가할수록 양자 구속 효과로부터 electronic state와 conduction band edge 사이의 에너지 차이의 증가 때문이다. 또한 시분해 광루미네센스 측정 결과 ZnTe의 두께가 증가할수록 양자점의 소멸 시간이 더 길게 측정되었는데, 이는 더 큰 양자점 일수록 엑시톤 오실레이터 강도가 감소하기 때문에 더 긴 소멸 시간을 나타내는 것을 확인할 수 있었다. 결과적으로 본 연구는 ZnTe 두께 변화를 통해 양자점의 에너지 밴드를 제어할 수 있으며, 양자점의 효율 향상을 할 수 있는 좋은 방법임을 제시하고 있다.

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