• Journal of Chest Surgery
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• v.25 no.4
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• pp.347-355
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• 1992

The precise mechanism of the Excitation-Contraction Coupling is still uncertain. But the concept that Ca2+ induced Ca2+ release [CICR] from the Ryanodine receptor in the sarcoplasmic reticulum [foot structure] may play a major role in E-C coupling has been widely accepted since 1970`s. It is believed that increased cytosolic Ca2+ followed by CICR is main contributor for E-C coupling of striated muscle. Resulting phenomena of ischemic /post-reperfusion myocyte is increased cytosolic Ca2+, even to the absence of Ca2+ in reperfusate. So intracellular inhibitor to CICR might prevent the ischemic and reperfusion damage of myocardial cells. The relatively purified foot protein, especially heavy sarcoplasmic reticulum rich, of the skeletal muscle was incorporated into the black lipid bilayer [Phosphatidyl ethanolamine: Phosphatidyl serine=l: 1]. Under the steady state of membrane potential [+20 mV], ionic current through Ryanodine receptor was measured with Cs+ as charge carrier. In the cis chamber [Cytoplasmic side], Mg2+ strongly inhibited CICR of Ryanodine receptor[Kd=6.2 nM]. In conclusion, naturally existing intracellular free Mg2+ can inhibit CICR from intracellular Ca2+ reservior [heavy SR]. So post-ischemic or post-reperfusing myocardium could be preserved using additional free Mg2+ in cardioplegic solution or reperfusate, otherwise the optimal concentration is undetermined.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1453-1454
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• 2011

We have investigated the effect of silicon contents (0~0.4 molar ratios) on the performance of solution processed silicon-indium-zinc oxide (SIZO) thin-film transistors (TFTs). Despites its solution processed channel layer, low annealed temperature below $200^{\circ}C$ in air has been used for SIZO-TFTs. The $V_{th}$ is shifted from -4.04 to 5.15 V as increasing Si ratio in the SIZO-TFTs. The positive shift of $V_{th}$ as increasing Si contents in SIZO system indicates that Si suppresses the carrier generation in the active channel layer since $V_{th}$ is defined as the voltage required accumulating sufficient charge carriers to form a conductive channel path.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.629-629
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• 2013

Graphene is a carbon based material and it has intriguing features, such as phenomenally strong, thin, flexible, transparent and conductive, those make it attractive for a broad range of applications.Unfortunately, graphene is extremely sensitive to contamination. When we fabricate graphene devices, electrical properties of graphene are altered [1], and the charge carrier mobility drops accordingly by orders of magnitude. This significant impact on electron mobility occurs because any surrounding medium could act as a dominant source of extrinsic scattering, which effectively reduces the mean free path of carriers [2,3]. The dominant contaminant is generated through fabrication stage by polymethyl methacrylate (PMMA) [4], or photo resist (PR). Surface contamination by these residues has long been a critical problem in probing graphene's intrinsic properties. If we clearly solve this problem, we can get highly performed graphene devices. Here, we will report on graphene cleaning process by Induced Coupled Plasma (ICP). We demonstrated how much decomposition of residue impact on improving electrical properties of graphene.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.5
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• pp.907-917
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• 2000

In this paper the network costing model alternatives for reasonable interconnection charging are suggested. The current interconnection charge regimes is based on fully distributed costing method. Basically this method doesn't consider the common carrier's efficient network cost because it reflects the actual cost of network In this paper, 1 suggest the basic structure of the network costing model fur applications of incremental costing method that considers the efficient cost based on economics-prospective. And I classify network cost with capital cost and operating cost and analysis their reasonable costing methods.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.315-318
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• 1998

Organic light-emitting diodes(OLEDs) or electroluminescent devices have attracted much attention because of their possible application as large-area light-emitting displays. Their structure was based on employing a multilayer device structure containing an emitting layer and a carrier transporting layer of suitable organic materials. In this study, several Tb complexes such as Tb(ACAC)$_3$(Phen), Tb(ACAC)$_3$(Phen-Cl) and Tb(TPB)$_3$(Phen) were synthesized and the photoluminescence(PL) and electroluminescence (EL) characteristics of their thin films were investigated by fabricating the devices having a structure of anode/HTL/terbium-oomplex/ETL/cathode, where TPD was used as an hole transporting and Alq$_3$ and TAZ-Si were used as an electron transporting materials. It was found that the photoluminescence(PL) and electroluminescence(EL) characteristics of these terbium complexes were dependent upon the ligands coordinated to terbium metal. Details on the explanation of electrical transport phenomena of the structure with I-V characteristics of the OLEDs using the trapped-charge-limited current(TCLC) model will be discussed.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.12
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• pp.39-46
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• 1996

In AlGaAs/GaAs HBT the temperature dependence of DC parameters was investigated over the temperature range between 95K and 580K. The temperature dependence of DC parameters depends on the relative contribution of each of the current components suc as emitter-injection-current, base-injection-current, bulk recombination current, interface recombination curretn, thermal generation ecurrent and avalanche current due to impact ionization within the collector space charge layer in a specific temperature. In this paper we investigated the temperature effects on DC parameters such as V$_{BE,ON}$ current gain, input and output characteristics, V$_{CE, OFF}$, R$_{E}$, R$_{C}$ and analyzed the origins, and extracted the qualitativ econditions for a stable HBTs against the temperature variation. Finally, in order to keep HBTs stable with respect to the variation of temperature, the valance-band-energy-discontinuity at emitter-base heterojunction should be large enough to enhance the effect of carrier suppression at a relatively high temperature. In addition the recombination centers, especially around collector junction, should be removed and the area of emitter and collector junction should be identical as well.

• Journal of Information Display
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• v.11 no.1
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• pp.1-7
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• 2010

The intermediate connectors play crucial roles in the performance of tandem organic light-emitting diodes (OLEDs) because they are required to facilitate charge carrier transport and to guarantee transparency for light transmission and deposition compatibility. Understanding the physical properties of the intermediate connector is not only fundamentally important but is also crucial to developing high-efficiency organic devices with a tandem structure. In this study, several effective intermediate connectors in tandem OLEDs using a doped or non-doped organic p-n heterojunction were systematically investigated by studying their interfacial electronic structures and corresponding device characteristics. The working mechanisms of the intermediate connectors are discussed herein by referring to their relevant energy levels with respect to those of the neighboring organic layers. The factors affecting the operation of the intermediate connectors in tandem OLEDs, as demonstrated herein, provide guidance for the identification of new materials and device architectures for high-performance devices.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.955-962
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• 2005

Power efficiency, lifetime and stable manufacturing processes are the crucial parameters for the success of organic light emitting diodes (OLEDs) in display and lighting applications. Highest power efficiencies of PIN-OLEDs for all principal colours and for bottom and top emission OLED structures have been demonstrated. The PIN structure, which means the incorporation of intentionally doped charge carrier transport layer in a suitable OLED layer setup, lowers the operating voltage to achieve highest power efficiencies. Up to now the n-doping of the electron transport layer has been done by alkali metal co-deposition. This has main draw-backs in terms of manufacturability, since the handling of large amounts of pure Cs is a basic issue in production lines. Here we present in detail results on PIN-OLEDs comprising a newly developed molecular n-dopant. All the previous OLED performance data based on PIN-OLEDs with alkali metal doping could be reproduced and will be further improved in the future. Hence, for the first time, a full manufacturing compatible PIN-OLED is available.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.877-880
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• 2003

A new class of light-emitting poly(p-phenylenevinylene) (PPV) derivatives. poly(9,9-di-n-octyfluorenyl- 2,7-vinylene) (PFV) and its PPV copolymers, poly[(9,9-di-n-octylfluorenyl-2,7-vinylene)-co-(1,4-phenylenevinylene)]s [Poly(FV-co-PV)s] was synthesized through Gilch polymerization, and their light-emitting properties were investigated. The copolymers showed almost the same UV absorption and PL emission as the PFV homopolymer, regardless of copolymer composition. Interestingly, the EL spectra of these devices were similar to the PL spectra of the corresponding polymer film. However, the EL devices constructed from the poly(FV-co-PV)s showed 10 times higher efficiency than the devices constructed from the PFV homopolymer. This higher efficiency is possibly a result of better charge carrier balance in the copolymer systems due to the lower HOMO level (${\sim}5.5$ eV) of the poly(FV-co-PV)s in comparison to the PFV (${\sim}5.7$ eV).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.7
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• pp.594-599
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• 2005

In this paper, we report the properties of Mo metal employed as PMOS gate electrode. Mo on $SiO_2$ was observed to be stable up to $900^{\circ}C$ by analyzing the Interface with XRD. C-V measurement was performed on the fabricated MOS capacitor with Mo Bate on $SiO_2$. The stability of EOT and work-function was verified by comparing the C-V curves measured before and after annealing at 600, 700, 800, and $900^{\circ}C$. C-V hysteresis curve was performed to identify the effect of fired charge. Gate-injection and substrate-injection of carrier were performed to study the characteristics of $Mo-SiO_2$ and $SiO_2-Si$ interface. Sheet resistance of Mo metal gate obtained from 4-point probe was less than $10\;\Omega\Box$ that was much lower than that of polysilicon.