• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1190-1193
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• 2005

In recent years, as the demands of VBNS and VDSL increase, the development of kernel parts of optical communication such as PLC(Planar Light Circuit), Coupler, and WDM elements increases. The alignment and the attachment technology are very important in the fabrication of optical elements. In this paper, the optical alignment characteristics of multi-axis ultra precision stage were studied. The alignment algorithms were studied for applying to the ultra precision multi-axis stage. The alignment algorithm is comprised of field search and peak search algorithms. The contour of optical power signals can be obtained by field search and the precise coordinate can be found out by peak search. Two kinds of alignments, such as 1 ch. input vs. 1 ch. output optical stack, and 1 ch. input vs. 8 ch. output PLC stacks were performed for investigating the alignment characteristics.

• Journal of the Semiconductor & Display Technology
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• v.6 no.1 s.18
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• pp.17-22
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• 2007

Recent new packages such as MCP(Multi-Chip Package), QDP(Quadratic Die Package) and DDP(Dual Die Package) have stack type configuration. This kind of multi-layer package is thicker than single layer package. So there is need for the low height looping technology in wirebonder to make these packages thinner. There is stiff zone above ball in wirebonder wire which is called HAZ(Heat Affect Zone). When making low height loop (below $80\;{\mu}m$) with traditional forward loop, stiff wire in HAZ(Heat Affected Zone) above ball is bended and weakened. So the traditional forward looping method cannot be applied to low height loop. SSB(stand-off stitch) wire bonding method was applied to many packages which require very low loops. The drawback of SSB method is making frequent errors at making ball, neck damage above ball on lead and the weakness of ball bonding on lead. The alternative looping method is BNL(ball neckless) looping technology which is already applied to some package(DDP, QDP). The advantage of this method is faster in bonding process and making little errors in wire bonding compared with SSB method. This paper presents the result of BNL looping technology applied in assembly house and several issues related to low loop height consistence and BNL zone weakness.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.203-208
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• 2005

In recent years, as the demands of VBNS and VDSL increase, the development of kernel parts of optical communication such as PLC(Planar Light Circuit), Coupler, and WDM elements increases. The alignment and the attachment technology are very important in the fabrication of optical elements. In this paper, the optical alignment characteristics of multi-axis ultra precision stage were studied. The alignment algorithms were studied for applying to the ultra precision multi-axis stage. The alignment algorithm is comprised of field search and peak search algorithms. The contour of optical power signals can be obtained by field search and the precise coordinate can be found out by peak search. Two kinds of alignments, such as 1 ch. input vs. 1 ch. output optical stack, and 1 ch. input vs. 8 ch. output PLC stacks were performed for investigating the alignment characteristics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.1
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• pp.44-49
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• 2022

In this paper, we investigated current (I)- and voltage (V)-sweeping properties in a double-stack structure, Ge₂Sb₂Te₅/Ti/W-doped Ge₈Sb₂Te₁₁, a candidate medium for applications to multilevel phase-change memory. 200-nm-thick and W-doped Ge₂Sb₂Te₅ and W-doped Ge₈Sb₂Te₁₁ films were deposited on p-type Si(100) substrate using magnetron sputtering system, and the sheet resistance was measured using 4 point-probe method. The sheet resistance of amorphous-phase W-doped Ge₈Sb₂Te₁₁ film was about 1 order larger than that of Ge₂Sb₂Te₅ film. The I- and V-sweeping properties were measured using sourcemeter, pulse generator, and digital multimeter. The speed of amorphous-to-multilevel crystallization was evaluated from a graph of resistance vs. pulse duration (t) at a fixed applied voltage (12 V). All the double-stack cells exhibited a two-step phase change process with the multilevel memory states of high-middle-low resistance (HR-MR-LR). In particular, the stable MR state is required to guarantee the reliability of the multilevel phase-change memory. For the Ge₂Sb₂Te₅ (150 nm)/Ti (20 nm)/W-Ge₈Sb₂Te₁₁ (50 nm), the phase transformations of HR→MR and MR→LR were observed at t<30ns and t<65ns, respectively. We believe that a high speed and stable multilevel phase-change memory can be optimized by the double-stack structure of proper Ge-Sb-Te films separated by a barrier metal (Ti).

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.176-176
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• 2010

One of the critical issues for applications of flexible organic thin film transistors (OTFTs) for flexible electronic systems is the electrical stabilities of the OTFT devices, including variation of the current on/off ratio (Ion/Ioff), leakage current, threshold voltage, and hysteresis under repetitive mechanical deformation. In particular, repetitive mechanical deformation accelerates the degradation of device performance at the ambient environment. In this work, electrical stability of the pentacene organic thin film transistors (OTFTs) employing multi-stack hybrid encapsulation layers was investigated under mechanical cyclic bending. Flexible bottom-gated pentacene-based OTFTs fabricated on flexible polyimide substrate with poly-4-vinyl phenol (PVP) dielectric as a gate dielectric were encapsulated by the plasma-deposited organic layer and atomic-layer-deposited inorganic layer. For cyclic bending experiment of flexible OTFTs, the devices were cyclically bent up to 105 times with 5mm bending radius. In the most of the devices after 105 times of bending cycles, the off-current of the OTFT with no encapsulation layers was quickly increased due to increases in the conductivity of the pentacene caused by doping effects from $O_2$ and $H_2O$ in the atmosphere, which leads to decrease in the Ion/Ioff and increase in the hysteresis. With encapsulation layers, however, the electrical stabilities of the OTFTs were improved significantly. In particular, the OTFTs with multi-stack hybrid encapsulation layer showed the best electrical stabilities up to the bending cycles of $10^5$ times compared to the devices with single organic encapsulation layer. Changes in electrical properties of cyclically bent OTFTs with encapsulation layers will be discussed in detail.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.3 s.8
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• pp.1-8
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• 2005

IEEE WAVE(Wireless Access in Vehicular Environment) is being developed to operate in 5 GHz DSRC band to provide cars moving at high-speed with vehicle-to-vehicle and vehicle-to-roadside communication. IEEE P 1609.3 of the WAVE protocol stack defines how multiple channels are used based on the exchange of provider-service-tables (PST) and user-service-tables (UST) for rapid link establishment and data transmission. This paper presents the design and implementation of an IEEE WAVE multi-channel transmission emulator that we have developed to study the operation of protocol and applications. Applications for a public-safety and a download service have been implemented and are shown to operate effectively on top of the emulator.

• Journal of the Korean Institute of Gas
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• v.13 no.6
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• pp.1-8
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• 2009

This study pertains to damping device to reduce vibrational responses and shocks in multi-directions. To enhance the capability of disk spring damper which works for vertical vibration and shock, a multi-directional damper is proposed, which contains wedge system as well as disk spring stack. Wedge system converts horizontal load into vertical load. A mathematical model is proposed and investigated for the nonlinear behaviors of the disc spring damper containing wedge system. The results accord with the experimental results. Equivalent viscous damping in vertical and horizontal directions are found based upon energy dissipated.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.143-148
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• 2013

This paper study about multi-beam for ditection of arrival estimation in wireless system. estimate a direction of arrival of target in multi input-output array antennas system. Beam steering method are divided by beam steering method of elevation angle or beam forming method, stack beam steering, frequency steering, phase steering radar and digital beam forming radar. Proposed algorithm is combined SVD method and antenna weight error compensation method with phase and amplitude compensation to effectivity beam steering. Through simulation, we were analysis of performance that general algorithm and proposed target estimation algorithm in this paper. It was proved to improved proposal algorithm than general algorithm in target direction of arrival estimation.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.324-326
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• 2016

In this study, we have investigated indium tin zinc oxide (ITZO) as an active channel for non-volatile memory (NVM) devices. The electrical and memory characteristics of NVM devices using multi-stack gate insulator SiO2/SiOx/SiOxNy (OOxOy) with Si-rich SiOx for charge storage layer were also reported. The transmittance of ITZO films reached over 85%. Besides, ITZO-based NVM devices showed good electrical properties such as high field effect mobility of 25.8 cm2/V.s, low threshold voltage of 0.75 V, low subthreshold slope of 0.23 V/dec and high on-off current ratio of $1.25{\times}107$. The transmission Fourier Transform Infrared spectroscopy of SiOx charge storage layer with the richest silicon content showed an assignment at peaks around 2000-2300 cm-1. It indicates that many silicon phases and defect sources exist in the matrix of the SiOx films. In addition, the characteristics of NVM device showed a retention exceeding 97% of threshold voltage shift after 104 s and greater than 94% after 10 years with low operating voltage of +11 V at only 1 ms programming duration time. Therefore, the NVM fabricated by high transparent ITZO active layer and OOxOy memory stack has been applied for the flexible memory system.

• Journal of the Korean institute of surface engineering
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• v.44 no.5
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• pp.226-231
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• 2011

Graphene was coated on STS 316L by electro spray coating method to improve its properties of corrosion resistance and contact resistance. Exfoliated graphite (graphene) was made of the graphite by chemical treatment. Graphene is distributed using dispersing agent, and STS 316L was coated with diffuse graphene solution by electro spray coating method. The structure of the exfoliated graphite was analyzed using XRD and the coating layer of surface was analyzed by using SEM. Analysis showed that multi-layered graphite structure was destroyed and it was transformed into fine layers graphene structure. And the result of SEM analysis on the surface and the cross section, graphene layer was uniformly formed with 3~5 ${\mu}m$ thickness on the surface of substrate. Corrosion resistance test was applied in the corrosive solution which is similar to the PEM fuel cell stack inside. And interfacial contact resistance test was measured to simulate the internal operating conditions of PEM fuel cell stack. The results of measurements show that stainless steel coated with graphene was improved in corrosion resistance and surface contact resistance than stainless steel without graphene coating layer.