1,474 research outputs found
Predictive Current Control of Distribution Static Condenser (D-STATCON) for Reactive Power Compensation in Flexible AC Transmission System (FACTS)
No full textThis paper describes the modeling and current control techniques of a distribution static condenser (D-STATCON). The current control is based on the predictive and the space vector PWM scheme. The predictive current controlled PWM D-STATCON can maintain its performance with reactive power compensation and fixed switching frequency. By using the space vector control, low ripple and offset in the current and the voltage as well as fast dynamic responses are achieved with a small DC link capacitance employed
Start up Inrush Current Elimination Technique for New Zero Current Switching Series Resonant Rectifier with Low Harmonic Distortion
No full textAtomically Thin Synapse Networks on Van Der Waals Photo-Memtransistors
No full textA new type of atomically thin synaptic network on van der Waals (vdW) heterostructures is reported, where each ultrasmall cell (approximate to 2 nm thick) built with trilayer WS2 semiconductor acts as a gate-tunable photoactive synapse, i.e., a photo-memtransistor. A train of UV pulses onto the WS2 memristor generates dopants in atomic-level precision by direct light-lattice interactions, which, along with the gate tunability, leads to the accurate modulation of the channel conductance for potentiation and depression of the synaptic cells. Such synaptic dynamics can be explained by a parallel atomistic resistor network model. In addition, it is shown that such a device scheme can generally be realized in other 2D vdW semiconductors, such as MoS2, MoSe2, MoTe2, and WSe2. Demonstration of these atomically thin photo-memtransistor arrays, where the synaptic weights can be tuned for the atomistic defect density, provides implications for a new type of artificial neural networks for parallel matrix computations with an ultrahigh integration density.11Nsciescopu
Identification of Point Defects in Atomically Thin Transition-Metal Dichalcogenide Semiconductors as Active Dopants
No full textSelective doping in semiconductors is essential not only for monolithic integrated circuity fabrications but also for tailoring their properties including electronic, optical, and catalytic activities. Such active dopants are essentially point defects in the host lattice. In atomically thin two-dimensional (2D) transition-metal dichalcogenides (TMDCs), the roles of such point defects are particularly critical in addition to their large surface-to-volume ratio, because their bond dissociation energy is relatively weaker, compared to elemental semiconductors. In this Mini Review, we review recent advances in the identifications of diverse point defects in 2D TMDC semiconductors, as active dopants, toward the tunable doping processes, along with the doping methods and mechanisms in literature. In particular, we discuss key issues in identifying such dopants both at the atomic scales and the device scales with selective examples. Fundamental understanding of these point defects can hold promise for tunability doping of atomically thin 2D semiconductor platforms.11Nsciescopu
역률개선을 위한 자기에너지 궤환기법의 간단한 삼상 단일전력단 AC/DC 컨버터
No full textA simple three-phase single-stage AC/DC forward converter with transformer magnetic energy feedback technique for power factor correction is proposed. The operational principle of the proposed converter is presented. The proposed converter gives the good power factor correction, low line current harmonic distortions, and tight output voltage regulation. The prototype shows high power power factor with low line current harmonics
Mobile Interaction: A New Approach to Designing Optimized Button Layout for Mobile Phone
No full textRecommended from our members
Korean art and the avant-garde dilemma
No full textThe thesis covers Korean avant-garde art history and the dilemma that faced Korean artists at the end of the Japanese Colonial Period (1910-1945). Current literature adequately details avant-garde as progressive fine arts; however, there is limited literature on Korean art in this period. This thesis suggests the term avant-garde dilemma to indicate Korean artists‘ difficulty in style selection to follow a traditional aesthetical trend or progressive socio-political attitude for the foundation of Korean post-modernism. A salient démarche is found when Korean political avant-garde artists meet this dilemma in the midst of the Korean Demonstration Era (1976-1989) that initiates the decline of aesthetical activism and Demonstrative Art. Several styles of avant-garde dilemma after the Korea War are critiqued in the avant-garde evolution; subsequently, there arise hybrid styles between socio-political avant-garde and aesthetical avant-garde styles in Contemporary Korean Art. The examples included are Nam-Jun Baik‘s Video Art (a combination of art and technology), Do-Ho Suh‘s combination of meticulous sculpture with installation to satire Korean neo-capitalist society, Doo-Shik Lee‘s combination of oriental color with western gesture, and Suk-Chang Hong‘s free calligraphy to combine still-life, landscape, calligraphy, and scribbling
Schwartz & Moon 모형을 이용한 국내 인터넷 포탈 산업 內 기업의 가치평가 사례
No full text학위논문(석사) - 한국과학기술원 : 테크노경영전공, 2007.2, [ vii, 93 p. ]본 논문은 변동성이 높은 인터넷 기업의 가치를 계산한 Schwartz & Moon 가치평가모형(2000년, 2001년)의 개선을 목적으로 쓰여졌다. 가장 핵심적인 논문의 목표는 모형의 원가구조를 변경하는 것이다. 경쟁환경에서, 변동비 비율(변동비가 매출액에서 차지하는 비율)을 상수로 보거나 산업평균으로 회귀하는 stochastic 과정을 따른다는 기존 Schwartz & Moon 연구의 가치평가모형에는 문제가 있을 수 있는데, 왜냐하면 변동비 비율은 미래경쟁상황, 즉 미래 산업 내 순위와 매우 높게 관련되어 있기 때문이다. 예를 들면 어떤 산업의 주도적 기업은 건강한 수익성을 갖게 되는 것이 일반적이지만 후발기업은 수익성이 악화되어 어려움을 겪는 경우가 많다. 1위로써 거의 독점적인 시장 지배력을 행사하는 기업의 경쟁력이 계속 유지되기 쉽고 후발사업자나 경쟁사를 이를 뒤집기 어려운 것이 현실이다. 특히 인터넷 사업에서 이러한 경쟁상황에 따른 수익성의 차별화는 더 두드러지는데, 이는 인터넷 산업이 winner-takes-all 구조를 갖고 있기 때문이다. 따라서 현 경쟁상황을 반영한 변동비 비율과 향후의 경쟁상황을 확률적으로 접근한 변동비 비율이 동시에 반영될 경우 좀 더 현실에 가까운 모형의 개선이라고 할 수 있다. 이러한 새로운 원가구조의 개념을 먼저 제시하고, 더 나아가서 모형의 활용도를 높이기 위해 NHN, 다음커뮤니케인션즈, 엠파스 세 회사로 이루어진 한국 인터넷 포털 산업에 대한 사례 분석을 시행했다. 기존 연구 모형대로 가치를 평가하고, 본 논문의 개선된 원가구조를 적용하여 가치를 평가한 후 서로 비교해 본 결과, 본 논문의 결과가 좀 더 시장가치에 근접하게 산출되었는데, 이는 경쟁상황을 고려한 원가구조가 상수나 산업평균 수렴의 원가구조보다 더 우월한 가치평가모형임을 말해 준다고 할 수 있다.한국과학기술원 : 테크노경영전공
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