• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.384-384
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• 2012

We report nonvolatile memory properties of poly (3, 4-ethylenedioxythiophene) (PEDOT) thin films grown by vapor phase polymerization using FeCl3 as an oxidant. Liquid-bridge-mediated transfer method was employed to remove FeCl3 for generation of pure PEDOT thin films. From the electrical measurement of memory device, we observed voltage induced bipolar resistive switching behavior with ON/OFF ratio of 103 and reproducibility of more than 103 dc sweeping cycles. ON and OFF states were stable up to 104 seconds without significant degradation. Cyclic voltammetry data illustrates resistive switching effect can be attributed to formation and rupture of conducting paths due to oxidation and reduction of PEDOT. The maximum current before reset process was found to be increase linearly with increase in compliance current applied during set process.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.2
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• pp.191-197
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• 2016

In this paper, we investigated the hotcarrier injection (HCI) mechanism, one of the most important reliability issues, in 10 nm node Input/Output (I/O) bulk FinFET. The FinFET has much intensive HCI damage in Fin-bottom region, while the HCI damage for planar device has relatively uniform behavior. The local damage behavior in the FinFET is due to the geometrical characteristics. Also, the HCI is significantly affected by doping profile, which could change the worst HCI bias condition. This work suggested comprehensive understanding of HCI mechanisms and the guideline of doping profile in 10 nm node I/O bulk FinFET.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.3
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• pp.370-377
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• 2017

This paper presents a simple noise margin (NM) model of MOS current mode logic (MCML) gates especially in CMOS processes where a large device mismatch deteriorates logic reliability. Trade-offs between speed and logic reliability are discussed, and a simple yet accurate NM equation to capture process-dependent degradation is proposed. The proposed NM equation is verified for 130-nm, 110-nm, 65-nm, and 40-nm CMOS processes and has errors less than 4% for all cases.

• Electronics and Telecommunications Trends
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• v.35 no.3
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• pp.55-65
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• 2020

With the development of nonvolatile memory technology, Intel has released the Optane datacenter persistent memory module (DCPMM) that can be deployed in the dual in-line memory module. The results of research and experiments on Optane DCPMMs are significantly different from the anticipated results in previous studies through emulation. The DCPMM can be used in two different modes, namely, memory mode (similar to volatile DRAM: Dynamic Random Access Memory) and app direct mode (similar to file storage). It has buffers in 256-byte granularity; this is four times the CPU (Central Processing Unit) cache line (i.e., 64 bytes). However, these properties are not easy to use correctly, and the incorrect use of these properties may result in performance degradation. Optane has the same characteristics of DRAM and storage devices. To take advantage of the performance characteristics of this device, operating systems and applications require new approaches. However, this change in computing environments will require a significant number of researches in the future.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.491-497
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• 2007

As dispersed generators was driven in condition interconnecting with utility, it could cause a variety of new effects to the original distribution system that was running as considered only the one-way power flow. Therefore, the protection devices that is builted in distribution system should be designed to be able to operate with disposing of not only a fault of the generator, but also utility condition. Especially, the fault of the feeder interconnected with Dispersed Generator can cause the islanding phenomenon of open DG(Dispersed Generators). This phenomenon has many problems such as a machinery damage, electricity qualify degradation and a difficulty of the system recovery. In the fault therefore, we must separate Dispersed Generator from the system quickly. In this paper, for the fault classification of the interconnected DG and the outside feeder we judge the fault of the interconnected DG and the outside feeder in HMI through data provided by IED(Intelligent Electronic Device) on the network and decide whether it operates or not by sending the result to each relay.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.8 s.251
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• pp.756-763
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• 2006

PEMFC has several technical problems such as water management, long term stability and performance degradation as. PEMFC has been studied not only to solve water management, but also to generate power in stable manner to system by using a hybrid system with auxiliary energy storage device. The purpose of this study is to couple PEMFC with supercapacitor to make a hybrid system and to design and test control strategies for stable power generation in case of changing output power. The polarization curve and dynamic behaviors while changing power were investigated to find out characteristics of PEMFC stack. A DC/DC converter was fabricated in order to increase fuel cell and supercapacitor voltage and to charge supercapacitor. We found that the operation strategy 2 was recommended to the system because of solving water management problem and increasing the dynamic behavior.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.471-471
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• 2013

Highly stable and high performance amorphous oxide semiconductor thin film transistors (TFTs) were fabricated using 4-mercaptophenol (4MP) doped ZnO by atomic layer deposition (ALD). The 4 MP concentration in ZnO films were varied from 1.7% to 5.6% by controlling Zn: 4MP pulses. The carrier concentrations in ZnO thin films were controlled from $1.017{\times}10^{20}$/$cm^3$ to $2,903{\times}10^{14}$/$cm^3$ with appropriate amount of 4MP doping. The 4.8% 4MP doped ZnO TFT revealed good device mobility performance of $8.4cm^2V-1s-1$ and on/off current ratio of $10^6$. Such 4MP doped ZnO TFTs were stable under ambient conditions for 12 months without any apparent degradation in their electrical properties. Our result suggests that 4 MP doping can be useful technique to produce more reliable oxide semiconductor TFT.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.209-210
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• 2007

This paper describes the various wavelengths of electrical arc on overhead contact line for improvement of the current collection performance. The tests are performed with the arc measuring device and a welding machine to generate electrical are artificially. The experimental result shows the electrical are on overhead contact line and pantograph could be analyzed by artificial discharge.

• Journal of information and communication convergence engineering
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• v.15 no.1
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• pp.37-42
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• 2017

The constrained application protocol (CoAP) can be used for remotely controlling various sensor devices in Internet of Things (IoT) networks. In CoAP, to support the handover of a mobile sensor device, service discovery and message transmission needs to be repeated, although doing so would increase the handover delay significantly. To address this limitation of CoAP, a centralized CoAP scheme has been proposed. However, it tends to result in performance degradation for an inter-domain handover case. In this letter, we propose a distributed CoAP handover scheme to support the inter-domain handover. In the proposed scheme, a distributed mobility agent (DMA) is used for managing the location of mobile sensors in a domain and performing handover control operations with its neighboring DMAs in a distributed manner. A performance comparison reveals that the proposed scheme offers a performance improvement of up to 29.5% in terms of the handover delay.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.249-252
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• 1997

Electroluminescence(EL) devices based on organic thin layers have attracted lot of interests because of their possible application as large-area display-emitting display. One of the problems of such devices is lifetime of the cell, where the degradation of the cell is partially due to the crystalliyzation of organic layers. In large part, this problem can be solved by using a multilayer device structure prepared by vapor deposition technique. In this study, blue light-emitting multilayer organic electroluminescence devices were fabricated vsing Poly (9-vinylcarbaEole) (PVK) and 2- (4-tert-butylphenyl)-5-(4$^{#}$-bis-phenyl) 1,3,4-oxadiazole (PBO) as hole trasport and electron transport material, respectively, where trim(8-hyd roxyquinolinate) aluminum (Al $q_3$) was used as a luminescenct material. A cell structure of glass sub- strate/indume-tin-oxide(ITO)/PCK/Al $q_3$/PBD/Mg:In was employed. Blue emission peak at 510nm was observed with this cell structure.e.