• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1024-1027
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• 2006

The electrical and the optical properties of organic light-emitting devices (OLEDs), with and without various kinds of multiple heterostructures were investigated. The efficiency in green OLEDs were significantly enhanced by the structure of the multiple heterostructures acting as a hole transport layer (HTL) rather than by the number of periods. These results indicate that highly efficient green OLEDs utilizing multiple heterostructures acting as a HTL can be fabricated.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.1047-1052
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• 2003

Controlling carrier transport in light emitting polymers is extremely important for their efficient use in organic opto-electronic devices [1]. Here we show that the interactions between single wall carbon nanotubes (SWNTs) and conjugated polymers can be used to modify the overall mobility of charge carriers within nanotube-polymer nanocomposites. By using a unique, double emitting-organic light emitting diodes (DE-OLEDs) structure. we have characterized the hole transport within electroluminescent nanocomposites (nanotubes in poly (m-phenylene vinylene-co-2,5-dioctoxy-p-phenylene) or PmPV). We have shown using this idea that single devices with color tunability can be fabricated. It is seen that SWNTs in PmPV are responsible for hole trapping, leading to shifts in the emission wavelengths. Our results could lead to improved organic optical amplifiers, semiconducting devices, and displays.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.179.2-179.2
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• 2014

Carbon nanotubes (CNT)-metal contacts play an important role in nanoelectronics applications such as field-effect transistor (FET) devices. Using Al and (10,0) CNT, we have recently showed that the CNT-metal contacts mediated via topological defects within CNT exhibits intrinsically low contact resistance, thanks to the preservation of the sp2 bonding network at the metal-CNT contacts.[1] It is well-established that metals with good wetting property such as Pd consistently yield good contacts to both metallic and semiconducting CNTs. In this work, the electronic and charge transport properties of the interfaces between capped CNT and Pd will be investigated based on first-principles computations and compared with previous results obtained for the Al electrodes.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.54.1-54.1
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• 2012

Recent significant development of organic electronics is worthy of notice for its practical application as well as fundamental understandings. Complementary-like logic circuit is a key factor to realize actual operating organic electronic devices since its advantages of low power dissipation, good noise margin and stable operations. In this reason, studies on ambipolar properties of organic materials which can act as either n-type or p-type are getting more attentions. Performances of ambipolar transistors vary a lot along its molecular structures and film properties. When properly fabricated, balanced hole and electron mobilities over 1 cm2/Vs were observed recently. Study of charge transport in ambipolar organic transistors to understand this high performance was carried out through charge modulation spectroscopy.

• 세라미스트
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• 제21권1호
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• pp.98-111
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• 2018

The lead-based perovskite (CH3NH3PbI3) material has a high molar coefficient, high crystallinity at low temperature, and long range of balanced electron-hole transport length. In addition, PCE of perovskite solar cells (PSCs) has been dramatically improved by over 22% by amending the electronic quality of perovskite and by using state-of-the-art hole transporting materials (HTMs) such as tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) due to enhanced charge transport toward the electrode via properly aligned energy levels with respect to the perovskite. Replacing the spiro-OMeTAD with new HTMs with the desired properties of appropriate energy levels, high hole mobility in its pristine form, low cost, and easy processable materials is necessary for attaining highly efficient and stable PSCs, which are anticipated to be truly compatible for practical application. Furthermore, Recently Pb-free perovskite materials much attention as an alternative light-harvesting active layer material instead of lead based perovskite in photovoltaic cells. In this work, we demonstrate a Pb-free perovskite material for the light harvesting and emitter as optoelectronic devices.

• 한국컴퓨터정보학회논문지
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• 제24권5호
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• pp.41-47
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• 2019

A BIS(Bus Information System) collects, processes and analyzes information such as real-time location and operation status during bus operation. And It is a system that provides valid information to citizens, drivers, traffic centers and bus companies. Transport information system sent by an each bus is collected through GPS(Global Positioning System), DSRC(Dedicated Short Range Communications), Beacon and passed to transport information center. BIS data by collected is handled and analyzed. Next, it is transmitted to citizen, drivers and bus companies in real time. The result of 5 times simulation satisfied the test criteria(error range ${\pm}10m$) with an average error range of 3.306m, and the reliability is increased. In this paper, we propose a improved location transfer component that can provide users to quicker and more accurate location information than existing BIS using GPS of smart phone. It can be seen that reliability is improved by securing improved bus position data.

• International Journal of Computer Science & Network Security
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• 제21권2호
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• pp.40-43
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• 2021

In the article of instability on the peak power level, duration and repetition period of a multifrequency space-time signal, we calculated the maximum values of the errors of the parameters of the laws of spatial-phase-frequency control. Requirements for the accuracy of the location of the phase centers of the emitters in a cylindrical phased array antenna with pyramidal horns; it is advisable to calculate the radiation field using single-stage and multi-stage distribution laws. The phase centers of individual radiation sources of a cylindrical phased array antenna have been studied; they have almost no effect on the duration and period of recurrence.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.682-685
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• 2002

In this paper, we defined necessary operations and functional blocks of a multiplexer for 3-D video systems and present our multiplexer design. We adopted the ITU-T's recommendation(H.222.0) to define the operations and functions of the multiplexer and explained the data structures and details of the design for multiview image processing. The data structure of TS(Transport Stream) and PES (Packetized Elementary Stream) in ITU-T Recommendation H.222.0 does not fit our multiview image processing system, because this recommendation is fur wide scope of transmission of non-telephone signals. Therefore, we modified these TS and PES stream structures. The TS is modified to DSS(3D System Stream) and PES is modified to SPDU(DSS Program Data Unit). We constructed the multiplexer through these modified DSS and SPDU. The number of multiview image channels is nine, and the image class employed is MPEG-2 SD(Standard Definition) level which requires a bandwidth of 2∼6 Mbps. The required clock speed should be faster than 54(= 6 ${\times}$ 9)㎒ which is the outer interface clock speed. The inside part of the multiplexer requires a clock speed of only 1/8 of 54㎒, since the inside part of the multiplexer operates by the unit of byte. we used ALTERA Quartus II and the FPGA verification for the simulation.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.26-26
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• 2003

Lithium storage electrodes for rechargeable batteries require mixed electronic-ionic conduction at the particle scale in order to deliver desired energy density and power density characteristics at the device level. Recently, lithium transition metal phosphates of olivine and Nasicon structure type have become of great interest as storage cathodes for rechargeable lithium batteries due to their high energy density, low raw materials cost, environmental friendliness, and safety. However, the transport properties of this family of compounds, and especially the electronic conductivity, have not generally been adequate for practical applications. Recent work in the model olivine LiFePO$_4$, showed that control of cation stoichiometry and aliovalent doping results in electronic conductivity exceeding 10$^{-2}$ S/cm, in contrast to ~10$^{-9}$ S/cm for high purity undoped LiFePO$_4$. The increase in conductivity combined with particle size refinement upon doping allows current rates of >6 A/g to be utilized while retaining a majority of the ion storage capacity. These properties are of much practical interest for high power applications such as hybrid electric vehicles. The defect mechanism controlling electronic conductivity, and understanding of the microscopic mechanism of lithiation and delithiation obtained from combined electrochemical and microanalytical techniques, will be discussed

• Transactions on Electrical and Electronic Materials
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• 제6권5호
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• pp.221-224
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• 2005

To overcome of poor electron injection in organic light-emitting diodes (OLEDs) with Al cathode, a thin layer of inorganic insulating materials, like as LiF, is inserted between an Al cathode and an organic electron transport layer. Though the device, mentioned above, improves both turn on voltage and luminescent properties, it has some problems like as thickness restriction, less than 2 nm, and difficulty of deposition control. On the other hand, Li organic complex, Liq, is less thickness restrictive and easy to deposit and it also enhances the performance of devices. This paper reports the improved electron injection on OLEDs with another I A group metal complex, Potassium quinolate (Kq), as an electron injection material. OLEDs with organic complexes showed improved turn-on voltage and luminous efficiency which are remarkably improved compared to OLEDs with Al cathode. Especially, OLEDs with Kq have longer life time than OLEDs with Liq.