• Title/Summary/Keyword: enhanced degradation

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A Backup Node Based Fault-tolerance Scheme for Coverage Preserving in Wireless Sensor Networks (무선 센서 네트워크에서의 감지범위 보존을 위한 백업 노드 기반 결함 허용 기법)

  • Hahn, Joo-Sun;Ha, Rhan
    • Journal of KIISE:Information Networking
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    • v.36 no.4
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    • pp.339-350
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    • 2009
  • In wireless sensor networks, the limited battery resources of sensor nodes have a direct impact on network lifetime. To reduce unnecessary power consumption, it is often the case that only a minimum number of sensor nodes operate in active mode while the others are kept in sleep mode. In such a case, however, the network service can be easily unreliable if any active node is unable to perform its sensing or communication function because of an unexpected failure. Thus, for achieving reliable sensing, it is important to maintain the sensing level even when some sensor nodes fail. In this paper, we propose a new fault-tolerance scheme, called FCP(Fault-tolerant Coverage Preserving), that gives an efficient way to handle the degradation of the sensing level caused by sensor node failures. In the proposed FCP scheme, a set of backup nodes are pre-designated for each active node to be used to replace the active node in case of its failure. Experimental results show that the FCP scheme provides enhanced performance with reduced overhead in terms of sensing coverage preserving, the number of backup nodes and the amount of control messages. On the average, the percentage of coverage preserving is improved by 87.2% while the additional number of backup nodes and the additional amount of control messages are reduced by 57.6% and 99.5%, respectively, compared with previous fault-tolerance schemes.

Robust Feature Extraction Based on Image-based Approach for Visual Speech Recognition (시각 음성인식을 위한 영상 기반 접근방법에 기반한 강인한 시각 특징 파라미터의 추출 방법)

  • Gyu, Song-Min;Pham, Thanh Trung;Min, So-Hee;Kim, Jing-Young;Na, Seung-You;Hwang, Sung-Taek
    • Journal of the Korean Institute of Intelligent Systems
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    • v.20 no.3
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    • pp.348-355
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    • 2010
  • In spite of development in speech recognition technology, speech recognition under noisy environment is still a difficult task. To solve this problem, Researchers has been proposed different methods where they have been used visual information except audio information for visual speech recognition. However, visual information also has visual noises as well as the noises of audio information, and this visual noises cause degradation in visual speech recognition. Therefore, it is one the field of interest how to extract visual features parameter for enhancing visual speech recognition performance. In this paper, we propose a method for visual feature parameter extraction based on image-base approach for enhancing recognition performance of the HMM based visual speech recognizer. For experiments, we have constructed Audio-visual database which is consisted with 105 speackers and each speaker has uttered 62 words. We have applied histogram matching, lip folding, RASTA filtering, Liner Mask, DCT and PCA. The experimental results show that the recognition performance of our proposed method enhanced at about 21% than the baseline method.

Preparation and Characterization of Electrospun PAN/TiO2 Fiber Mat by Electron Beam Irradiation (전자선 조사에 의한 PAN/TiO2 전기방사 나노섬유 제조 및 특성분석)

  • Kang, Phil-Hyun;Jeun, Joon-Pyo;Seo, Dong-Kwon;Kim, Hyun-Bin;Nho, Young-Chang
    • Polymer(Korea)
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    • v.36 no.1
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    • pp.47-52
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    • 2012
  • Abstract: In this study, PAN/$TiO_2$ fiber mats were fabricated from polyacrylonitrile (PAN) and titanium(IV) butoxide ($Ti(OBu)_4$) by an electrospinning method with various solution concentrations, applied voltages and solution flow rates. The fiber mats were irradiated with an electron beam to induce structural crosslinking and enhance photocatalytic activity. As a result, uniform and bead-free fibers without pits or cracks on surface were obtained at 5 wt% of $Ti(OBu)_4$ solution with 15 kV and 0.02 mL/min flow rate. The PAN/$TiO_2$ fiber mats were irradiated with an electron beam of 1.14 MeV acceleration voltage, 4 mA of current and $1{\times}10^4kGy$. Electron beam irradiation was enhanced the photocatalytic activity of PAN/$TiO_2$ nano fiber mat. The photocatalytic activity of the PAN/$TiO_2$ fiber mat was analyzed by degradation of methylene blue and volatile organic compounds.

Improved breakdown characteristics of Ga2O3 Schottky barrier diode using floating metal guard ring structure (플로팅 금속 가드링 구조를 이용한 Ga2O3 쇼트키 장벽 다이오드의 항복 특성 개선 연구)

  • Choi, June-Heang;Cha, Ho-Young
    • Journal of IKEEE
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    • v.23 no.1
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    • pp.193-199
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    • 2019
  • In this study, we have proposed a floating metal guard ring structure based on TCAD simulation in order to enhance the breakdown voltage characteristics of gallium oxide ($Ga_2O_3$) vertical high voltage switching Schottky barrier diode. Unlike conventional guard ring structures, the floating metal guard rings do not require an ion implantation process. The locally enhanced high electric field at the anode corner was successfully suppressed by the metal guard rings, resulting in breakdown voltage enhancement. The number of guard rings and their width and spacing were varied for structural optimization during which the current-voltage characteristics and internal electric field and potential distributions were carefully investigated. For an n-type drift layer with a doping concentration of $5{\times}10^{16}cm^{-3}$ and a thickness of $5{\mu}m$, the optimum guard ring structure had 5 guard rings with an individual ring width of $1.5{\mu}m$ and a spacing of $0.2{\mu}m$ between rings. The breakdown voltage was increased from 940 V to 2000 V without degradation of on-resistance by employing the optimum guard ring structure. The proposed floating metal guard ring structure can improve the device performance without requiring an additional fabrication step.

Soil Carbon Storage in Upland Soils by Biochar Application in East Asia: Review and Data Analysis (바이오차를 이용한 밭 토양 탄소 저장: 동아시아 지역 연구 리뷰 및 데이터 분석)

  • Lee, Sun-Il;Kang, Seong-Soo;Choi, Eun-Jung;Gwon, Hyo-Suk;Lee, Hyoung-Seok;Lee, Jong-Mun;Lim, Sang-Sun;Choi, Woo-Jung
    • Korean Journal of Environmental Agriculture
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    • v.40 no.3
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    • pp.219-230
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    • 2021
  • BACKGROUND: Biochar is a solid material converted from agricultural biomass such as crop residues and pruning branch through pyrolysis under limited oxygen supply. Biochar consists of non-degradable carbon (C) double bonds and aromatic ring that are not readily broken down by microbial degradation in the soils. Due to the recalcitrancy of C in biochar, biochar application to the soils is of help in enhancing soil carbon sequestration in arable lands that might be a strategy of agricultural sector to mitigate climate change. METHODS AND RESULTS: Data were collected from studies on the effect of biochar application on soil C content conducted in East Asian countries including China, Japan and Korea under different experimental conditions (incubation, column, pot, and field). The magnitude of soil C storage was positively correlated (p < 0.001) with biochar application rate under field conditions, reflecting accumulation of recalcitrant black C in the biochar. However, The changes in soil C contents per C input from biochar (% per t/ha) were 6.80 in field condition, and 12.58 in laboratory condition. The magnitude of increment of soil C was lower in field than in laboratory conditions due to potential loss of C through weathering of biochar under field conditions. Biochar production condition also affected soil C increment; more C increment was found with biochar produced at a high temperature (over 450℃). CONCLUSION: This review suggests that biochar application is a potential measures of C sequestration in agricultural soils. However, as the increment of soil C biochar was affected by biochar types, further studies are necessary to find better biochar types for enhanced soil C storage.

Development of Cucumber Cotyledon in View of Metabolic Pathways and Organelle (세포내 소기관과 물질대사의 관점에서 오이 떡잎의 발달)

  • Kim, Dae-Jae
    • Journal of Life Science
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    • v.31 no.8
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    • pp.778-785
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    • 2021
  • The germination of cucumber seeds begins with the degradation of reserved oil to fatty acids within the lipid body, which are then further metabolized to acyl-CoA. The acyl-CoA moves from the lipid body to the glyoxysome following β-oxidation for the production of acetyl-CoA. As an initial carbon source supplier, acetyl-CoA is an essential molecule in the glyoxylate cycle within the glyoxysome, which produces the metabolic intermediates of citrate and malate, among others. The glyoxylate cycle is a necessary metabolic pathway for oil seed plant germination because it produces the metabolic intermediates for the tricarboxylic acid (TCA) cycle and for gluconeogenesis, such as the oxaloacetate, which moves to the cytosol for the initiation of gluconeogenesis by phophoenolpyruvate carboxykinase (PEPCK). Following reserved oil mobilization, the production and transport of various metabolic intermediates are involved in the coordinated operation and activation of multiple metabolic pathways to supply directly usable carbohydrate in the form of glucose. Furthermore, corresponding gene expression regulation compatibly transforms the microbody to glyoxysome, which contains the organelle-specific malate synthase (MS) and isocitrate lyase (ICL) enzymes during oil seed germination. Together with glyoxylate cycle, carnitine, which mediates the supplementary route of the acetyl-CoA transport mechanism via the mitochondrial BOU (A BOUT DE SOUFFLE) system, possibly plays a secondary role in lipid metabolism for enhanced plant development.

The Effect of Recycled Aggregate Produced by the New Crushing Device with Multi-Turn Wings and Guide Plate on the Mechanical Properties and Carbonation Resistance of Concrete (다중 회전 날개 및 가이드 판 설치 파쇄장치를 통해 제작된 순환골재가 콘크리트의 역학적 특성 및 탄산화 저항성에 미치는 영향)

  • Cho, Sung-Kwang;Kim, Gyu-Yong;Eu, Ha-Min;Kim, Yong-Rae;Lee, Chul-Min
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.2
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    • pp.135-142
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    • 2021
  • In this work, multi-turn wings and guide plates are installed on recycled aggregate crushing devices to improve existing low recycled aggregate quality. Simulation analysis to evaluate the crushing efficiency of the new device shows enhanced crushing efficiency since the installation of guide plates shreds most of the inputs inside the crushing drum, and the multi-turn wings and guide plates induce rebound and circulation of the aggregate. Through this, the new device was found to be more economical and efficient than the existing recycled aggregate crushing device. Also, the amount of cement paste and mortar attached to the surface of the aggregate was smaller than that of the existing recycled aggregate, and it was found that the mechanical properties and elastic modulus deterioration were reduced. However, the carbonation resistance of concrete was not improved to the level of natural aggregates due to the remaining tiny cement paste and mortar on the surface of the new recycled aggregate. Therefore, it is deemed necessary to further research and experiment such as device improvement or binder development to reduce durability degradation of concrete mixed with new recycled aggregate.

Effect of Neungi (Sarcodon aspratus) Mushroom and Its Protease Addition on the Meat Tenderizing (능이버섯 및 Protease효소의 첨가가 연육에 미치는 영향)

  • Cho, Hee-Yeon;Jeong, Seon-Hwa;Cho, Nam-Seok
    • Journal of the Korean Wood Science and Technology
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    • v.32 no.5
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    • pp.39-44
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    • 2004
  • This study was carried out to investigate the tenderizing effect of Neungi mushroom (Sarcodon aspratus) powder and its protease. The addition of Neungi mushroom powder and its protease enhanced water retention values (WRY) of meat. The WRY of meat was increased 26.8% by protease addition, compared to 13.8% WRV by sugar addition. This increase in WRY derived to the increase of water soluble fraction in the meat texture by hydrolysis of meat protein, and had the meat tenderized. Concerned to the meat tenderizing effect, the addition of Neungi mushroom powder and its protease have decreased of meat hardness and gave similar tenderizing effect, as compared to commercial tenderizer, papain. The decreasing rates of meat hardness were 51.6% of Neungi mushroom powder, 58.5% of its protease, and 563% of commercial tenderizer, papain. This tenderizing effect of protease attributed to the degradation of muscle fiber protein in meat, such as actin, myosin and connectin etc. The addition of Neungi mushroom to foods gives significant changes in food color, mainly decreasing lightness.

Enhanced Cycle Performance of Bi-layer Structured LMO-NCM Positive Electrode at Elevated Temperature (겹층구조의 LMO-NCM 복합양극을 통한 고온 사이클 수명개선 연구)

  • Yoo, Seong Tae;Ryu, Ji Heon
    • Journal of the Korean Electrochemical Society
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    • v.25 no.4
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    • pp.184-190
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    • 2022
  • Spinel LiMn2O4 (LMO) and layered LiNi0.5Co0.2Mn0.3O2 (NCM) are widely used as positive electrode materials for lithium-ion batteries. LMO and NCM positive electrode materials have a complementary properties. LMO has low cost and high safety and NCM materials show a relatively high specific capacity and better cycle life even at elevated temperature. Therefore, the LMO and NCM active materials are blended and used as a positive electrode in large-size batteries for electric vehicles (xEV). In this study, the cycle performance of a blended electrode prepared by simply mixing LMO and NCM and a bi-layer electrode in which two electrode layers aree sequentially coated are compared. The bi-layer electrode prepared by composing the same ratio of both active materials has similar capacity and cycle performance to the blend electrode. However, the LN electrode coated with LMO first and then NCM is the best in the full cell cycle performance at elevated temperature, and the NL electrode, in which NCM is first coated with LMO has a faster capacity degradation than the blended electrode because LMO is mainly located on the top of the electrode adjacent to electrolyte and graphite negative electrode. Also, the LSTA (linear sweep thermmametry) analysis results show that the LN bi-layer electrode in which the LMO is located inside the electrode has good thermal stability.

Enhanced Degradation of Residual Cadusafos in Soils by the Microbial Agent of Cadusafos-degrading Sphingobium sp. Cam5-1 (미생물제(Sphingobium sp. Cam5-1) 처리에 따른 토양 중 카두사포스의 분해효과)

  • Jehyeong Yeon;Joon-hui Chung;Han Suk Choi;Young-Joon Ko;Dayeon Kim;Sihyun An;Jae-Hyung Ahn;Gui Hwan Han;Hang-Yeon Weon
    • Korean Journal of Environmental Agriculture
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    • v.42 no.4
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    • pp.346-352
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    • 2023
  • Cadusafos, an organophosphorus insecticide, has been commonly used against various pests worldwide. Organophosphorus pesticides have shorter half-lives and lower toxicities than organochlorine pesticides. However, excessive use of Cadusafos can increase pest resistance and issues with acetylcholine biomagnification, potentially resulting in human toxicity. In this study, we investigated the effect of a Cadusafos-degrading microbial agent (CDMA) prepared using Sphingobium sp. Cam5-1, which was previously reported to effectively degrade residual Cadusafos in soil. Experiments were conducted under both controlled laboratory and greenhouse field conditions. Under laboratory conditions, CDMA (106 cfu/g soil application rate) decomposed 97% of Cadusafos in the soil in the untreated control after 21 days. Additionally, when CDMA (106 cfu/g soil) was mixed with quicklime, 99% of Cadusafos was decomposed within 3 days. Under greenhouse field conditions, the combined effect of CDMA (106 cfu/g soil) and quicklime was not observed. However, CDMA (106 cfu/g soil) application alone was capable of decomposing 91% of Cadusafos after 3 days. These results indicate that CDMA can effectively decompose high residual levels of Cadusafos in soils under field conditions using a low inoculum rate.