• Journal of Information Display
• /
• 제10권2호
• /
• pp.87-91
• /
• 2009

Highly efficient red phosphorescent OLEDs (PHOLEDs) with a simple, organic, triple-layer structure was developed using the narrow-bandgap fluorescent host material bis(10-hydroxybenzo[h] quinolinato)beryllium complex (Bebq2) and the deep-red dopant tris(1-phenylisoquinoline)iridium (Ir(piq)3). The maximum current and power efficiency values of 12.71 cd/A and 16.02 lm/W, respectively, with an extremely low doping technology of 1%, are demonstrated herein. The results reveal a practical, cost-saving host dopant system for the fabrication of highly efficient PHOLEDs involving the simple structure presented herein, with a reduction of expensive Ir dopants.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제7권12호
• /
• pp.3055-3070
• /
• 2013

This paper proposes an improved carrier frequency offset (CFO) and sampling frequency offset (SFO) estimation scheme for orthogonal frequency division multiplexing (OFDM) based broadcasting system with cyclic delay diversity (CDD) antenna. By exploiting a periodic nature of channel transfer function, cyclic delay and pilot pattern with a maximum channel power are carefully chosen, which helps to enable a robust estimation of CFO and SFO against the frequency selectivity of the channel. As a performance measure, a closed-form expression for the achievable mean square error of the proposed scheme is derived and is verified through simulations using the parameters of the digital radio mondiale standard. The comparison results show that the proposed frequency estimator is shown to benefit from properly selected delay parameter and pilot pattern, with a performance better than the existing estimator.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 1998년도 학술발표회논문집
• /
• pp.112-115
• /
• 1998

We investigate the qualities of organic materials by which can manufacture organic thin films for solar cells and make thin films for insulation layers of an insulated cable. We give pressure stimulation into organic thin films and detect the induced displacement current. In processing of a device manufacture, We can see the process is good from the change of a surface pressure for organic thin films and transfer ratio of area per molecule. The structure of manufactured device is Au/organic thin films(polyimide)/Au and I-V characteristic of the device is measured from 0[V] to +5[V]. The maximum value of measured current is increased as the number of accumulated layers are decreased. The resistance for the number of accumulated layers, the energy density for an input voltage show desired results, and the insulation of a thin film is better as the interval between electrodes is larger.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.1571-1572
• /
• 2009

Polymer solar cells were fabricated with gravure printing process and the effect of thermal annealing of gravure printed organic layer was investigated. The layer structure of polymer solar cells is glass / ITO / hole transfer layer / active layer / Al structure was fabricated. For the active layer, 1:1 ratio of poly-3-hexylthiophene (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) mixture was applied. The P3HT/PCBM blend was gravure printed onto the substrates. The effect of thermal annealing was investigated by changing annealing time and the number of printing. Maximum 3.6% of power conversion efficiency was achieved with gravure printing of organic layer and thermal annealing in this work.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1993년도 하계학술대회 논문집 B
• /
• pp.689-691
• /
• 1993

This paper describes an induction heating system which is developed for CRT manufacturing. This system consists of a buck chewer, a voltage source full-bridge inverter, and a series resonant circuit with a matching transformer. A series resonant scheme is employed, and operated at the zero phase of the resonant load by PLL. This ensures maximum power transfer, good efficiency and reliability of the system. Implementation of a prototype rated of 3 kW 450 kHz is described and experimental results are given.

• 한국전기전자재료학회논문지
• /
• 제27권12호
• /
• pp.857-862
• /
• 2014

In this paper, we designed and fabricated electromagnetic induction based scaffold type energy harvester. For energy harvesting, mechanical energy of vertical motion is transferred to rotational energy using rack gear and multiplying gear was used to maximize energy transfer. To optimize design parameters, physical structure of energy harvester was modeled using finite element method. The effect of multiplying gear ratio and frequency levels of applied mechanical energy on energy generation efficiency are analyzed by computer simulation and experimental test. Experimental results showed that maximum 25.36 W of electric power can be achieved at the frequency of 2 Hz and 1:77 of gear ratio with only 5 mm of vertical changes on scaffold structure.

• Nuclear Engineering and Technology
• /
• 제55권5호
• /
• pp.1687-1707
• /
• 2023

This paper presents a molten salt reactor (MSR) design parameter sensitivity study using a nodal dynamic modelling methodology with explicitly modified point kinetics equation and Mann's model for heat transfer. Six parameters that can impact MSR safety are evaluated. A MATLAB-Simulink model inspired by Thorcon's 550MWth MSR is used for parameter evaluations. A safety envelope was formed to encapsulate power, maximum and minimum temperature, and temperature-induced reactivity feedback. The parameters are perturbed by ±30%. The parameters were then ranked by their subsequent impact on the considered safety envelope, which ranks acceptable parameter uncertainty. The model is openly available on GitHub.

• 대한전자공학회논문지TC
• /
• 제48권2호
• /
• pp.90-94
• /
• 2011

본 논문에서는 고주파 대역 중에서 에너지 전송과 관련되어 정류 회로의 구조와 특성을 분석하고, 최대의 효율을 이끌어 낼 수 있는 방안을 찾고자 한다. 13.56MHz에서의 입력 신호를 DC 변환하여 실험 및 측정을 하였다. 정류회로는 반파 정류회로, 전파정류회로 브릿지 정류회로로 나눌 수 있고, 최대 효율을 갖기 위해서 다양한 정류 회로를 전산 모의 실험하였다. 현재까지의 연구 내용은 passive 소자를 이용한 효율 개선에 중점을 두고 실험을 하였다. 정류 효율에 영향을 미치는 요소는 소자의 특성에 좌우하며, 이번 실험에서는 약 70%의 효율을 측정할 수 있었으며, 보다 개선된 소자를 사용함으로서 낮은 입력에서 높은 효율을 얻을 수 있었다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2016년도 전력전자학술대회 논문집
• /
• pp.333-334
• /
• 2016

This paper proposes a new cascoded configuration for hybrid energy storage system (HESS) which consists of batteries and supercapacitor (SC) for Electric Vehicle applications. In this configuration,a resonant LLC converter is interfacedin series with a battery module and it converts a part of the energy from the batteries and transfer it to the dc-link bus. The LLC converter is controlled by a phase-shift angle between the primary and secondary switches to maintain a constant dc-link voltage and obtain soft-switching conditions for all the primary switches. By placing the SC moduleina cascoded concept, the rated voltage of SC can be reduced significantly compared with the conventional topologies. It helps save the cost and reduce the number of SC cells. The proposed configuration can operate with four different modes: feeding load, acceleration, regenerative braking andSC charging. A scaled-down prototype converter (2 kW, 600V output) is designed and tested to verify the advantages of the proposed topology. The maximum efficiency obtained with the proposed topology is 99%.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 하계학술대회 논문집
• /
• pp.401-401
• /
• 2009

Recently, demands for the development of compact, lightweight power supplies with higher power density and higher efficiency have been increased. Since Piezoelectric Transformer (PT) was emerged in device and material industry, it has been suggested as a viable alternative to the magnetic transformer in some applications. PT has some advantages such as low profile and mechanical energy transfer with little electromagnetic interface (EMI). Also, PT can provide high voltage stepping ratio with good isolation and requires no copper windings saving copper usage especially for large voltage conversion differences. Conventional control of PT converter has mainly two-way. One is the pulse frequency modulation (PFM) control method and the other is the pulse width modulation (PWM) control with frequency fixed method. It is known that the maximum PT efficiency can be obtained when it operates near the resonant frequency of the PT. And, also PT's resonant frequency moves according to the load condition. Therefore, selection of PT converter control method is very difficult. This paper analyzes general piezo-electric converter modeling and proposes a guide-line to selection of control method and stabilization control.