• Title/Summary/Keyword: Performance Degradation Rate

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Maximizing WSQ Compression Rate by Considering Fingerprint Image Quality (지문 영상 품질을 고려한 WSQ 최대 압축)

  • Hong, Seung-Woo;Lee, Sung-Ju;Chung, Yong-Wha;Choi, Woo-Yong;Moon, Dae-Sung;Moon, Ki-Young;Jin, Chang-Long;Kim, Hak-Il
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.20 no.3
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    • pp.23-30
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    • 2010
  • Compression techniques can be applied to large-scale fingerprint systems to store or transmit fingerprint data efficiently. In this paper, we investigate the effects of FBI WSQ fingerprint image compression on the performance of a fingerprint verification system using multiple linear regressions. We propose a maximum compression using fingerprint image quality score. Based on the experiments, we can confirm that the proposed approach can compress the fingerprint images up to 3 times more than the fixed compression ratio without significant degradation of the verification accuracy.

A Study on Morphology Control of (Ga1-xZnx)(N1-xOx) Nanofibers according to the Composition and Crystallinity of Oxide Nanofibers Synthesized by Electrospinning (전기방사로 합성된 산화물 나노섬유의 조성 및 결정화도에 따른 (Ga1-xZnx)(N1-xOx) 나노섬유의 형상 제어 연구)

  • Kim, Jeong Hyun;Oh, Sung-Tag;Lee, Young-In
    • Journal of Powder Materials
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    • v.28 no.3
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    • pp.259-266
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    • 2021
  • The (Ga1-xZnx)(N1-xOx) solid solution is attracting extensive attention for photocatalytic water splitting and wastewater treatment owing to its narrow and controllable band gap. To optimize the photocatalytic performance of the solid solution, the key points are to decrease its band gap and recombination rate. In this study, (Ga1-xZnx)(N1-xOx) nanofibers with various Zn fractions are prepared by electrospinning followed by calcination and nitridation. The effect of the composition and crystallinity of electrospun oxide nanofibers on the morphology and optical properties of the obtained solid-solution nanofibers are systematically investigated. The results show that the final shape of the (Ga1-xZnx) (N1-xOx) material is greatly affected by the crystallinity of the oxide nanofibers before nitridation. The photocatalytic properties of (Ga1-xZnx)(N1-xOx) with different Ga:Zn atomic ratios are investigated by studying the degradation of rhodamine B under visible light irradiation.

Impact of waste crumb rubber on concrete performance incorporating silica fume and fly ash to make a sustainable low carbon concrete

  • Muhammad, Akbar;Zahoor, Hussain;Pan, Huali;Muhammad, Imran;Blessen Skariah, Thomas
    • Structural Engineering and Mechanics
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    • v.85 no.2
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    • pp.275-287
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    • 2023
  • The use of environmental-friendly building materials is becoming increasingly popular worldwide. Compared to the normal concrete, rubber-based concrete is considered more durable, environmentally friendly, socially and economically viable. In this investigation, M20 grade concrete was designed and the fine aggregates were replaced with crumb rubber of two different micron sizes (0.221 mm and 0.350 mm). Fly ash (FA) and silica fume (SF) replaces the binder as supplementary cementitious materials at a rate of 0, 5, 10, 15, and 20% by weight. The mechanical properties of concrete including compressive strength, tensile, and flexural strength were determined. The polynomial work expectation validates the response surface approach (RSM) concept for optimizing SF and FA substitution. The maximum compressive strength (22.53 MPa) can be observed for the concrete containing 10% crumb rubber, 15% fly ash and 15% silica fume. The reduced unit weight of the rubberized concrete may be attributed to the lower specific gravity of the rubber particles. Two-way ANOVA with a significance criterion of less than 0.001 has been utilized with modest residual error from the lack of fit and the pure error. The predictive model accurately forecasts the variable-response relationship. Since, the crumb rubber is obtained from wasted tires incorporating FA and SF as a cementitious ingredient, it helps to significantly improve mechanical properties of concrete and reduce environmental degradation.

Efficient Memory Update Module for Video Object Segmentation (동영상 물체 분할을 위한 효율적인 메모리 업데이트 모듈)

  • Jo, Junho;Cho, Nam Ik
    • Journal of Broadcast Engineering
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    • v.27 no.4
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    • pp.561-568
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    • 2022
  • Most deep learning-based video object segmentation methods perform the segmentation with past prediction information stored in external memory. In general, the more past information is stored in the memory, the better results can be obtained by accumulating evidence for various changes in the objects of interest. However, all information cannot be stored in the memory due to hardware limitations, resulting in performance degradation. In this paper, we propose a method of storing new information in the external memory without additional memory allocation. Specifically, after calculating the attention score between the existing memory and the information to be newly stored, new information is added to the corresponding memory according to each score. In this way, the method works robustly because the attention mechanism reflects the object changes well without using additional memory. In addition, the update rate is adaptively determined according to the accumulated number of matches in the memory so that the frequently updated samples store more information to maintain reliable information.

Research on unsupervised condition monitoring method of pump-type machinery in nuclear power plant

  • Jiyu Zhang;Hong Xia;Zhichao Wang;Yihu Zhu;Yin Fu
    • Nuclear Engineering and Technology
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    • v.56 no.6
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    • pp.2220-2238
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    • 2024
  • As a typical active equipment, pump machinery is widely used in nuclear power plants. Although the mechanism of pump machinery in nuclear power plants is similar to that of conventional pumps, the safety and reliability requirements of nuclear pumps are higher in complex operating environments. Once there is significant performance degradation or failure, it may cause huge security risks and economic losses. There are many pumps mechanical parameters, and it is very important to explore the correlation between multi-dimensional variables and condition. Therefore, a condition monitoring model based on Deep Denoising Autoencoder (DDAE) is constructed in this paper. This model not only ensures low false positive rate, but also realizes early abnormal monitoring and location. In order to alleviate the influence of parameter time-varying effect on the model in long-term monitoring, this paper combined equidistant sampling strategy and DDAE model to enhance the monitoring efficiency. By using the simulation data of reactor coolant pump and the actual centrifugal pump data, the monitoring and positioning capabilities of the proposed scheme under normal and abnormal conditions were verified. This paper has important reference significance for improving the intelligent operation and maintenance efficiency of nuclear power plants.

Study on Internal Reforming Characteristic of 1 kW Solid Oxide Fuel Cell Stack (1 kW 고체산화물 연료전지 스택의 내부개질 특성 연구)

  • CHOI, YOUNGJAE;AHN, JINSOO;LEE, INSUNG;BAE, HONGYOUL;MOON, JIWOONG;LEE, JONGGYU
    • Journal of Hydrogen and New Energy
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    • v.28 no.4
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    • pp.377-383
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    • 2017
  • This paper presents the performance characteristics of a 1 kW solid oxide fuel cell (SOFC) stack under various internal reforming and fuel utilization conditions. The Research Institute of Industrial Science & Technology (RIST) developed the 9-cell stack using a $20{\times}20cm^2$ anode supported planar cell with an active area of $324cm^2$. In this work, current-voltage characteristic test, fuel utilization test, continuous operation, and internal reforming test were carried out sequentially for 765 hours at a furnace temperature of $700^{\circ}C$. The influence of fuel utilization and internal reforming on the stack performance was analyzed. When the 1 kW stack was tested at a current of 145.8 A with a corresponding fuel utilization of 50-70% (internal reforming of 50%) and air utilization of 27%, the stack power was approximately 1.062-1.079 kW. Under continuous operation conditions, performance degradation rate was 2.16%/kh for 664 hours. The internal reforming characteristics of the stack were measured at a current of 145.8. A with a corresponding fuel utilization of 60-75%(internal reforming of 50-80%) and air utilization of 27%. As fuel utilization and internal reforming ratio increased, the stack power was decreased. The stack power change due to the internal reforming ratio difference was decreased with increasing fuel utilization.

A Reputation based Cooperative Routing Scheme for End-to-End Reliable Communications in Multi-hop Wireless Networks (다중 홉 무선 네트워크에서 종단 간 신뢰성 통신을 위한 평판 기반의 협력적 라우팅 기법)

  • Kim, Tae-Hoon;Tak, Sung-Woo
    • Journal of Korea Multimedia Society
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    • v.12 no.11
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    • pp.1593-1608
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    • 2009
  • If a certain relay node in multi-hop wireless networks might become a malicious node that does not cooperate with other nodes or a selfish node, network throughput will be dramatically decreased. Most of existing ad hoc routing protocols assuming that the nodes will fully cooperate with other nodes do not resolve the problem of network performance degradation due to malicious and selfish nodes. This paper presents the CARE (Cooperative Ad hoc routing protocol based REputation) scheme incorporating the reputation management that can achieve a multi-hop wireless network with high throughput performance. The proposed scheme provides the horizontal cross-layer approach which can identify misbehaving malicious, selfish nodes dropped out of the hop-by-hop based packet processing in the network and then set up an optimal packet routing path that will detour misbehaving nodes. And the vertical cross-layer approach contained in the CARE scheme attempts to improve the quality of routing paths by exploiting the quality of link information received from the MAC layer. Besides, it provides high TCP throughput by exploiting the reputation values of nodes acquired from the network layer into the transport layer. A case study on experiments and simulations shows that the CARE scheme incorporating vertical and horizontal cross-layer approaches yields better performance in terms of the low rate of packet loss, fast average packet delivery time, and high TCP throughput between end-to-end nodes.

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Vibration Analysis of SAR Antenna Reflectors During Satellite Maneuver (위성 기동 시 SAR 안테나 반사판에 발생하는 진동 분석)

  • Kim, Tae-Hyun;Kim, Dae-Yeon;Suh, Jong-Eun;Han, Jae-Hung;Lee, Jae-Eun;Jung, Hwa-Young
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.3
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    • pp.225-231
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    • 2020
  • Recently, there has been an increasing demand for SAR satellite as it can be operated regardless of the weather condition. In general, main reflector of the SAR is formed of multiple deployable panels to increase performance in the constrained payload envelope. By nature, deployable structure lacks structural stiffness and it is vulnerable to external disturbances and excitation. In particular, SAR satellites may have high levels of vibration occurring at the antenna reflecting surface due to higher angular rate requirements. During image capturing it is important to keep high surface accuracy of the reflector for the quality of images. In this research, a performance degradation of deployable SAR antenna due to structural deformation is analyzed. Panels for main reflectors are assumed to be flexible structures and multi-body simulation environment is established. Then, deflection of the panel is calculated while the satellite performs maneuvers. In addition, antenna gain and beam pointing error are analyzed to determine how these deflections affect antenna performance and mission.

Effects of Vth adjustment ion implantation on Switching Characteristics of MCT(MOS Controlled Thyristor) (문턱전압 조절 이온주입에 따른 MCT (MOS Controlled Thyristor)의 스위칭 특성 연구)

  • Park, Kun-Sik;Cho, Doohyung;Won, Jong-Il;Kwak, Changsub
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.5
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    • pp.69-76
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    • 2016
  • Current driving capability of MCT (MOS Controlled Thyristor) is determined by turn-off capability of conducting current, that is off-FET performance of MCT. On the other hand, having a good turn-on characteristics, including high peak anode current ($I_{peak}$) and rate of change of current (di/dt), is essential for pulsed power system which is one of major application field of MCTs. To satisfy above two requirements, careful control of on/off-FET performance is required. However, triple diffusion and several oxidation processes change surface doping profile and make it hard to control threshold voltage ($V_{th}$) of on/off-FET. In this paper, we have demonstrated the effect of $V_{th}$ adjustment ion implantation on the performance of MCT. The fabricated MCTs (active area = $0.465mm^2$) show forward voltage drop ($V_F$) of 1.25 V at $100A/cm^2$ and Ipeak of 290 A and di/dt of $5.8kA/{\mu}s$ at $V_A=800V$. While these characteristics are unaltered by $V_{th}$ adjustment ion implantation, the turn-off gate voltage is reduced from -3.5 V to -1.6 V for conducting current of $100A/cm^2$ when the $V_{th}$ adjustment ion implantation is carried out. This demonstrates that the current driving capability is enhanced without degradation of forward conduction and turn-on switching characteristics.

Effect of Temperature on Formation of Polymer in Oxidation of Methyl Linoleate (Methyl Linoleate 산화중 중합체 형성에 미치는 온도의 영향)

  • Kim, In-Hwan;Kim, Chul-Jin;Kim, Dong-Hoon
    • Korean Journal of Food Science and Technology
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    • v.28 no.3
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    • pp.446-450
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    • 1996
  • To investigate the effect of heating conditions on the polymerization of methyl linoleate, the esters were heated at $60^{\circ}C,\;90^{\circ}C,\;120^{\circ}C$ and $150^{\circ}C$, respectively, with sparging oxygen for different periods of time. On the basis of the peroxide curve obtained at each of the four temperatures, four heating times were chosen for the analysis of the polymers and total oxidation products. Significant linear relationships were found between polymer contents and total oxidation product contents. The contents of polymers and their linkage types were analyzed by High Performance Size Exclusion Chromatography. The polymers formed at four temperatures were qualitatively identified as dimers. The dimers with peroxide linkages were detected from methyl linoleate oxidized at $60^{\circ}C\;and\;90^{\circ}C$ but they were not detected from methyl linoleate oxidized at $120^{\circ}C\;and\;150^{\circ}C$. Therefore, all dimers formed at $120^{\circ}C\;and\;150^{\circ}C$ seemed to be the ones with ether linkage or carbon to carbon linkage. The degradation rate of the dimers with peroxide linkages at $90^{\circ}C$ was faster than at $60^{\circ}C$.

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