• Title/Summary/Keyword: Operation layer

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Application of Micro Porous Layer (MPL) for Enhance of Electrode Performance in Phosphoric Acid Fuel Cells (PAFCs) (인산형 연료전지(PAFC)의 전극 성능 향상을 위한 미세다공층(MPL)의 적용)

  • Jihun Ha;Sungmin Kang;You-Kwan Oh;Dong-Hyun Peck
    • Journal of the Korean Electrochemical Society
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    • v.27 no.1
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    • pp.32-39
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    • 2024
  • The key components of a Phosphoric acid fuel cell (PAFC) are an electrode catalyst, an electrolyte matrix and a gas diffusion layer (GDL). In this study, we introduced a microporous layer on the GDL of PAFC to enhance liquid electrolyte management and overall electrochemical performance of PAFC. MPL is primarily used in polymer electrolyte membrane fuel cells to serve as an intermediate buffer layer, effectively managing water within the electrode and reducing contact resistance. In this study, electrodes were fabricated using GDLs with and without MPL to examine the influence of MPL on the performance of PAFC. Internal resistance and polarization curves of the unit cell were measured and compared to each other to assess the impact of MPL on PAFC electrode performance. As the results, the application of MPL improved power density from 170.2 to 192.1 mW/cm2. MPL effectively managed electrolyte and water within the matrix and electrode, enhancing stability. Furthermore, the application of MPL reduced internal resistance in the electrode, resulting in sustained and stable performance even during long-term operation.

Object-Oriented Database for Integrated Control of Distributed FMS (분산 FMS의 통합제어를 위한 객체지향 데이타베이스)

  • 박장호;차상균
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.10
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    • pp.1935-1944
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    • 1994
  • FMS is a distributed system composed of various programmable manufacturing hardware such as robots and NC machines. For the autonomous operation of such a system, an integrated software layer for the control and monitoring in needed on top of the manufacturing hardware. However, constructing and maintaining such a software layer is difficult due to the complexity of a underlying FMS and its frequently changing nature. To cope with this problem, this paper proposes an object-oriented FMS integration model, in which objects acting as virtual manufacturing cells are instantiated for each physical cell in the underlying object-oriented database. Various other entities involved in manufacturing processes and their relationship to the cell objects are also captured in the database. This paper describes the structure of this object-oriented FMS database on our prototype implementation called FREE.

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An Offline FTL Algorithm to Verify the Endurance of Flash SSD (플래시 SSD의 내구성을 검증하기 위한 FTL 오프라인 알고리즘)

  • Jung, Ho-Young;Lee, Tae-Hwa;Cha, Jae-Hyuk
    • Journal of Digital Contents Society
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    • v.13 no.1
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    • pp.75-81
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    • 2012
  • SSDs(Solid State Drives) have many attractive features such as high performance, low power consumption, shock resistance, and low weight, so they replace HDDs to a certain extent. An SSD has FTL(Flash Translation Layer) which emulate block storage devices like HDDs. A garbage collection, one of major functions of FTL, effects highly on the performance and the lifetime of SSDs. However, there is no de facto standard for new garbage collection algorithms. To solve this problem, we propose trace driven offline optimal algorithms for garbage collection of FTL. The proposed algorithm always guarantees minimal number of erase operation. In addition, we verify our proposed algorithm using TPC trace.

Study on Selection of HTS Wire for Fabrication of Fault Current-limiting Type HTS Cables (사고전류 제한형 초전도케이블 제작을 위한 초전도 선재 선정에 관한 연구)

  • Heo, Soung-Ouk;Kim, Tae-Min;Han, Byung-Sung;Du, Ho-Ik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.26 no.12
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    • pp.904-908
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    • 2013
  • When an abnormal condition occurs due to a fault current at a consumer location where electricity is supplied through a high-capacity and high-$T_c$ superconducting(HTS) cable, the HTS cable would be damaged if there is no appropriate measure to protect it. Therefore, appropriate measures are needed to protect HTS cables. The fault-current-limiting HTS cable that was suggested in this study performs an ideal transport current function in normal operations and plays a role in limiting a fault current in abnormal operation (i.e., when a fault current is applied). It has a structure that facilitated its self-current-limiting ability through device change and reconfiguration in the existing HTS cable without extra switching equipment. To complete this structure, it is essential to investigate about the selection of the superconducting wire. Therefore, in this paper, HTS wire using two types of different stabilization layer is compared and examined the stability and current limiting properties under the existence of a fault current.

Inorganic ferroelectric materials for LC alignment for high performance display design

  • Lee, Won-Gyu;Choe, Ji-Hyeok;Na, Hyeon-Jae;Im, Ji-Hun;Han, Jeong-Min;Hwang, Jeong-Yeon;Seo, Dae-Sik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.11a
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    • pp.161-161
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    • 2009
  • Ion bombarded inorganic materials for LC alignment has been researched as it provides controllability in a nonstop process for producing high-resolution displays. Many optically transparent insulators such as $SiOx$ and a-C:H have been investigated as potential candidates for inorganic alignment materials. Even so, LC orientation on a new material with superior capacity is required to produce high-performance displays. Many inorganic materials with high permittivities can reduce the voltage losses due to the LC alignment layer that are a trade-off for its capacitance. The minimum voltage for device operation can be applied to the LC under low external voltage using these materials. This means that low power consumption for LCD applications can be achieved using a high-k alignment structure in which the LC can be driven effectively with a low threshold voltage. Among the many other potential high-k oxides, HfO2 is considered to be one of the most promising due to its remarkable properties of high dielectric constant, relatively low leakage current, large band gap (5.68 eV), and high transparency. Due to these characteristics, HfO2 can be used in LC alignment to increase the capacitance of the inorganic alignment layer for low-voltage driving of LCs.

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Adaptive Importance Channel Selection for Perceptual Image Compression

  • He, Yifan;Li, Feng;Bai, Huihui;Zhao, Yao
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.9
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    • pp.3823-3840
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    • 2020
  • Recently, auto-encoder has emerged as the most popular method in convolutional neural network (CNN) based image compression and has achieved impressive performance. In the traditional auto-encoder based image compression model, the encoder simply sends the features of last layer to the decoder, which cannot allocate bits over different spatial regions in an efficient way. Besides, these methods do not fully exploit the contextual information under different receptive fields for better reconstruction performance. In this paper, to solve these issues, a novel auto-encoder model is designed for image compression, which can effectively transmit the hierarchical features of the encoder to the decoder. Specifically, we first propose an adaptive bit-allocation strategy, which can adaptively select an importance channel. Then, we conduct the multiply operation on the generated importance mask and the features of the last layer in our proposed encoder to achieve efficient bit allocation. Moreover, we present an additional novel perceptual loss function for more accurate image details. Extensive experiments demonstrated that the proposed model can achieve significant superiority compared with JPEG and JPEG2000 both in both subjective and objective quality. Besides, our model shows better performance than the state-of-the-art convolutional neural network (CNN)-based image compression methods in terms of PSNR.

Performance Analysis of QoS Mechanism Using DiffServ in IPOA Networks (IPOA 망에서 DiffServ를 이용한 QoS 메커니즘의 성능분석)

  • 문규춘;최현호;박광채
    • Proceedings of the IEEK Conference
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    • 2000.11a
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    • pp.307-310
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    • 2000
  • ATM is the switching and multiplexing technology chosen by the ITU-T for the operation of B-lSDN. Basically, ATM technology is designed to combine the reliability of circuit switching with the efficiency and flexibility of packet switching technology. For servicing QoS in IPOA(IP over ATM) when the larger effort is given, it will be the good method that the original QoS benefits having ATM switching have in ATM layer underlying layer. The IETF has recently proposed Differentiated Services framework for provision of QoS. In this paper we analyse performance of two Diffserv mechanism. Threshold Dropping and Priority Scheduling. Threshold Dropping and Priority Scheduling can be regarded as basic mechanisms from which the other mechanisms have been derived. Hence comparative performance of these two mechanisms in providing required QoS is an important issue. In this Paper we carry out a performance comparison of the TD and PS mechanisms with the aim of providing the same level of packet loss to the preferred flow. Our comparison of the TD and PS allows us to determine resultant packet loss for the non-preferred flows as a function of various parameters of the two mechanisms.

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Reliability Evaluation of the WSW Device for Hot-carrier Immunity (핫-캐리어 내성을 갖는 WSW 소자의 신뢰성 평가)

  • 김현호;장인갑
    • Journal of the Korea Society of Computer and Information
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    • v.9 no.1
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    • pp.9-15
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    • 2004
  • New WSW(Wrap Side Wall) is proposed to decrease junction electric field in this paper. WSW process is fabricated after first gate etch, followed NM1 ion implantation and deposition & etch nitride layer. New WSW structure has buffer layer to decrease electric field. Also we compared the hot carrier characteristics of WSW and conventional. Also, we design a test pattern including pulse generator, level shifter and frequency divider, so that we can evaluate AC hot carrier degradation on-chip. It came to light that the universality of the hot carrier degradation between DC and AC stress condition exists, which indicates that the device degradation comes from the same physical mechanism for both AC and DC stress. From this universality, AC lifetime under circuit operation condition can be estimated from DC hot carrier degradation characteristics.

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Fabrication of 3-Dimensional Microstructures using Digital Micromirror Device (Digital Micromirror Device 를 이용한 3차원 마이크로구조물 제작)

  • Choi, Jae-Won;Ha, Young-Myoung;Choi, Kyung-Hyun;Lee, Seok-Hee
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.11 s.188
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    • pp.116-125
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    • 2006
  • MEMS and LIGA technologies have been used for fabricating microstructures, but their shape is not 3D because of difficulty for preparation of many masks. To fabricate 3D microstructures, microstereolithography technology based on Digital Micromirror Device($DMD^{TM}$) was introduced. It has no need of masks and is capable of fabricating high aspect ratio microstructures. In this technology, STL file is the standard format as the same of conventional rapid prototyping system, and 3D parts are fabricated by layer-by-layer according to 2D section sliced from STL file. The UV light source is illuminated to DMD which makes bitmap images of 2D section, and they are transferred and focused on resin surface. In this paper, we addressed optical design of microstereolithography system in consideration of light path according to DMD operation and image-forming on the resin surface using optical design program. To verify the performance of implemented microstereolithography system, 3D microstructures with complexity and high aspect ratio were fabricated.

GaAs/AlGaAs MQW waveguide phase modulator with optical bistability (광쌍안정을 갖는 GaAs/AlGaAs MQW 도파로형 위상 광변조기)

    • Korean Journal of Optics and Photonics
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    • v.7 no.3
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    • pp.280-286
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    • 1996
  • This paper describes operation mechanism of a novel optical waveguide phase modulator with optical bistability characteristics by self electro-optic effect. The fabricated device structure is an optical waveguide modulator, using a refractive index change by an applied electric field, parallel integrated with SEED with an electrical bistability. GaAs/AlGaAs MQW is used as the core layer of the waveguide modulator and the absorption layer of SEED. The absorbed optical power in SEED changes the diode voltage and controls the optical power propagating through the waveguide phase modulator. Optical bistability of waveguide phase modulator is experimentally obtained by using electrical bistability of SEED. Compared to other waveguide modulators, the proposed one has an asset that the lowest optical power is required to generate optical bistability.

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