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Enhanced Exchange Coupling of $Nd_2Fe_{14}B/Fe_3B$ Magnet Via Magnetic Field Treatment

  • Choong Jin Yang;Con Byung Park
    • Journal of Magnetics
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    • v.1 no.1
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    • pp.31-36
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    • 1996
  • An externally applied magnetic field during heat treating the $Nd_2Fe_{14}B/Fe_3B$ based spring magnet was found to enhance the exchange coupling between the hard and soft magnetic grains. More than 30% increase in $M_r/M_s$ values for melt-spun $Nd_2Fe_{73.5}Co_3$$(Hf_{1-x}Ga_x)B_{18.5}$ (x=0, 0.5, 1) alloys was resulted from a uniform distribution of $Fe_3B, \alpha-Fe$ and $Nd_2Fe_{14}B$ phases, and also from a reduced grain size of those phases by 20%. The externally applied magnetic field induced a uniform distribution of fine grains. A study of Mossbauer effect also report that the enhancement of total magnetization of nanocomposite $Nd_2Fe_{14}B/Fe_3B$ alloys is attributed to an increased formation of $Fe_3$B after magnetic annealing.

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Derivation of Zeros from Externally-loaded Feed-forward Element of Filter Network

  • Um, Keehong;Yoo, Sooyeup;Pinthong, Chairat
    • International Journal of Internet, Broadcasting and Communication
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    • v.6 no.1
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    • pp.9-12
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    • 2014
  • We present a mathematical method for calculation of transmission zero locations, determining a filtering characteristics of two-port systems. By adjusting element values based on the zero locations, the frequency-selectivity is characterized. The characteristic polynomial of ladder networks in externally-loaded feed-forward systems is considered by adopting chain matrices for subsystems. This method can be extended to other types of lumped systems with cross-coupled sections. We find out the zeros by solving characteristics polynomials of closed-form expressions in terms of Laplace impedances of elements. The pairs of complex zeros are shown to be solely from the cross-coupled portion of the system.

Flexural Behavior of RC beams Strengthened with Externally Bonded Prestressed CFRP Strips (외부 부착형 프리스트레스트 탄소섬유판으로 보강된 RC보의 휨 거동)

  • You Young Chan;Choi Ki Sun;Park Young-Hwan;Park Jong-Sup;Kim Keung Hwan
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05a
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    • pp.255-258
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    • 2005
  • Experimental study has been performed in order to investigate the behavior of RC beams strengthened with externally bonded prestressed CFRP (Carbon Fiber Reinforced Polymer) strips. A total of 7 specimens have been manufactured of which specimens strengthened with bonded CFRP strips considering the level of prestress as experimental variable, and a specimen with simply bonded CFRP strips. The following phenomena have been observed through the experimental results. The specimen with simply bonded CFRP strips failed below 50$\%$ of its tensile strength due to premature debonding. On the other hand, all the specimens strengthened with prestressed CFRP strips showed sufficient strengthening performance up to the ultimate rupture load of the CFRP strips. Also, it was observed that the cracking loads and yield loads of the strengthened beams were increased proportionally to the prestress level, but the maximum loads were nearly equal regardless of the prestress level.

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Analyze of the interfacial stress in reinforced concrete beams strengthened with externally bonded CFRP plate

  • Hadji, Lazreg;Daouadji, T. Hassaine;Meziane, M. Ait Amar;Bedia, E.A. Adda
    • Steel and Composite Structures
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    • v.20 no.2
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    • pp.413-429
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    • 2016
  • A theoretical method to predict the interfacial stresses in the adhesive layer of reinforced concrete beams strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) plate is presented. The analysis provides efficient calculations for both shear and normal interfacial stresses in reinforced concrete beams strengthened with composite plates, and accounts for various effects of Poisson's ratio and Young's modulus of adhesive. Such interfacial stresses play a fundamental role in the mechanics of plated beams, because they can produce a sudden and premature failure. The analysis is based on equilibrium and deformations compatibility approach developed by Tounsi. In the present theoretical analysis, the adherend shear deformations are taken into account by assuming a parabolic shear stress through the thickness of both the reinforced concrete beam and bonded plate. The paper is concluded with a summary and recommendations for the design of the strengthened beam.

The System Development of Externally Reforming MCFC CHP Proto Type (250 kW 발전용 용융탄산염 연료전지 기술 개발 (시스템 및 BOP 설계))

  • Lim, Hee-Chun;Ahn, Kyo-Sang;Kim, Do-Hyeong;Gang, Seung-Won;Kim, Beom-Ju
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.195-196
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    • 2007
  • This paper shortly describe the R&D results for developing of 250 kW externally reforming MCFC (Molten Carbonate Fuel Cell) CHP proto type. Conceptual Design and basic design were alredy completed and stack which was adapted new separator and components also prepared for operation and evaluation. In parallel with stack and system development, BOP such as PCS, blower, catalytic combustor and Reformer also designed and fabricated for evaluation. The system will be fabricated by the end of 2008 and operate and evaluate in 2009.

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Strain interaction of steel stirrup and EB-FRP web strip in shear-strengthened semi-deep concrete beams

  • Javad Mokari Rahmdel;Erfan Shafei
    • Steel and Composite Structures
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    • v.47 no.3
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    • pp.383-393
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    • 2023
  • Conventional reinforced concrete design codes assume ideal strain evolution in semi-deep beams with externally bonded fiber-reinforced polymer (EB-FRP) web strips. However, there is a strain interaction between internal stirrups and web strips, leading to a notable difference between code-based and experimental shear strengths. Current study provides an experiment-verified detailed numerical framework to assess the potential strain interaction under quasi-static monotonic load. Based on the observations, steel stirrups are effective only for low EB-FRP amounts and the over-strengthening of semi-deep beams prevents the stirrups from yielding, reducing its shear strength contribution. A notable difference is detected between the code-based and the study-based EB-FRP strain values, which is a function of the normalized FRP stress parameter. Semi-analytical relations are proposed to estimate the effective strain and stress of the components considering the potential strain interaction. For the sake of simplification, a linearized correction factor is proposed for the EB-FRP web strip strain, assuming its restraining effect as constant for all steel stirrup amounts.

Effects of Aqueous Extract from Lonicera Japonica Flower on Trimellitic Anhydride-induced Contact Hypersensitivity in BALB/c Mice (수용성 금은화 추출물이 Trimellitic Anhydride 유도 마우스 접촉성 과민반응에 미치는 영향)

  • Lee, Jung-No;Jeong, Seung-Il;Jang, Seon-Il
    • The Korea Journal of Herbology
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    • v.23 no.2
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    • pp.51-58
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    • 2008
  • Objectives : Trimellitic anhydride (TMA), a sensitizer that induces occupational asthma and atopic dermatitis, is widely used industrially to make epoxy and alkyd resins, plasticizers, high temperature polymer, and surfactants. The aim of this study was to investigative the effects of aqueous extracts of Lonicera japonica Flower(LJFAE) on TMA-induced contact hypersensitivity (CHS) in Balb/c mice. Methods : The dried flowers of L. japonica were extracted with distilled water at $100^{\circ}C$ for 7 h. The extract was freeze-dried following filteration through 0.45 ${\mu}m$ filter. Mice were orally administrated with or without LJFE of a different doses(25-100 mg/kg) for 28 days. In the challenge period, mice were externally applied at difference doses of LJFAE one time per day 30 min before TMA treatment. We examined the effects of LJFAE on the the serum levels of IgE and prostagladin E2 (PGE2), the Thl/Th2 cytokine production of spleen cells, ear swelling responses, and the leukocyte infiltration induced by TMA. Results : The orally and externally administration of LJFAE dose-dependently reduced the serum levels of IgE and PGE2 production as well as ear swelling responses and leukocyte infiltration in TMA-induced Balb/c mice. Furthermore, the levels of Thl (TNF-${\alpha}$, IFN-${\gammer}$, IL-2)/Th2 (IL-4, IL-5, IL-13) cytokine production from spleen cells stimulated with anti-CD3 and CD28 mAbs was markedly suppressed by the orally and externally treatment with LJFAE in a concentration dependent manner. Conclusions : These results suggest that LJFAE suppresses the inflammatory mediators and regulates the Thl/Th2 cytokines. Therefore, these properties may contribute to the strong anti-CHS response effect of LJFAE.

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Outpatient Prescription Pattern of Anti-inflammatory Drugs by Pediatricians and ENT Physicians in Ulsan City (울산 지역 소아청소년과 및 이비인후과에서의 항염증제 처방 형태 분석)

  • Kim, Sung-Chull;Kim, Young-Rok;Hwang, Jae-Yoon;Chang, Hyeun-Wook;Nam, Doo-Hyun
    • Korean Journal of Clinical Pharmacy
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    • v.20 no.3
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    • pp.205-212
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    • 2010
  • The prescription sheets for outpatients from July 2008 to June 2009 from 7 community pharmacies in Ulsan City were surveyed for the anti-inflammatory drug (AID) prescription pattern. The AID prescription rate of pediatricians and ENT physicians were 30.0% and 34.8%, respectively. The oral steroidal anti-inflammatory drugs (SAIDs) were prescribed as much as 3.9% by pediatricians and 10.3% by ENT physicians. The chiefly prescribed oral SAID was prednisolone in pediatric clinics and methylprednisolone in ENT clinics. Meanwhile the prescription rate of oral non-steroidal anti-inflammatory drug (NSAID) was 22.5% by pediatricians and 21.4% in ENT physicians. The most favorable NSAIDs were propionate derivatives in both clinics. In case of externally-applied SAIDs, the prescription rate of pediatricians was 3.6% and that of ENT physicians was 2.8%. Among them, nasal spray, inhalant and gargle formulations for upper respiratory infection (URI) treatment occupied 35.8% of externally-applied SAIDs in pediatric clinics and 59.7% in ENT clinics. Further, it was observed that ENT physicians favored much stronger SAIDs in Group III of ATC classification (75.4% of externally-applied SAIDs) than pediatricians (49.2%). In the survey of AID combination rate, pediatric clinics showed much lower rate (1.4% of total AID prescriptions) than ENT clinics (7.5%). Among them, the combination rate of oral SAID and oral NSAID by ENT physicians (52.2% of total AID combinations) was much higher than pediatricians (36.6%), which might be over-prescription of AID agents. In conclusion, the AID prescription rate as well as AID combination rate, especially in SAID prescriptions, was much higher in ENT than pediatric clinics, which implies the higher confidency on AID drugs of ENT physicians even though the severity of patient's symptom could be considered.

A Study on the Characteristics of Non-hierachical Arrangement of SANAA's Work by Space Syntax (공간구문론을 이용한 SANAA 작품의 비위계적 공간구성 특성 연구)

  • Lee, Ki-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.8
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    • pp.735-744
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    • 2016
  • This study attempted quantitative analysis by space syntax on the plan of a non-hierarchical arrangement, which selected SANAA's work after Almere Stadt Theater, and analyzed the difference in the quantitative value of the non-hierarchical arrangement in plan that appears externally. The analysis results were as follows. First, SANAA's spaces with a non-hierarchical arrangement plan that appears externally showed a definite quantitative value difference, and had a hierarchical space difference in the plan that does not appear externally. Second, the spaces with a high integration value also had a high connectivity value, which is indicated by increasing the number of space openings using the method of giving hierarchy to the non-hierarchical arrangement plan or adjusting the size of the room or location to grant hidden hierarchy. Third, SANAA used exterior corridor rather than interior corridor in grid-type plan to solve the accessibility problem, and the open coat spaces between rooms provide natural lighting and ventilation and are used as equipment that controls the hidden hierarchy of space at the same time.