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  • Title/Summary/Keyword: D/N value

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High Dose 60Coγ-Ray Irradiation of W/GaN Schottky Diodes

  • Kim, Jihyun;Ren, F.;Schoenfeld, D.;Pearton, S.J.;Baca, A.G.;Briggs, R.D.
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.4 no.2
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    • pp.124-127
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    • 2004
  • W/n-GaN Schottky diodes were irradiated with 60Coγrays to doses up to 315Mrad. The barrier height obtained from current-voltage (I-V) measurements showed minimal change from its estimated initial value of 0.4eV over this dose range, though both forward and reverse I-V characteristics show evidence of defect center introduction at doses as low as 150 Mrad. Post irradiation annealing at 500C increased the reverse leakage current, suggesting migration and complexing of defects. The W/GaN interface is stable to high dose of γrays, but Au/Ti overlayers employed for reducing contact sheet resistance suffer from adhesion problems at the highest doses.

A Experimental Study on the Heat Release Rate to activate Fire Detection Sensor (화재감지 센서 작동시간 및 열방출률에 대한 실험연구)

  • Hong, Sung-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.9
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    • pp.1358-1361
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    • 2012
  • This paper presents a study on the analysis for activation time and threshold value of heat detection sensor using HRR(Heat Release Rate). And it is represented to quantity of heat to activate heat detection sensor. The experiment is conducted to measure activation time and HRR of fire detection sensor burning alcohol and n-heptane. In order to burn the alcohol and n-heptane using 43.5cm(L)×43.5cm(W)×5cm(D) and 33cm(L)×33cm(L)×5cm(D) steel pan and the quantity of alcohol and n-heptane are 2.5 L and 650 g, respectively. The results show that peak HRR are in case of alcohol 66.13 kW and in case of n-heptane 151.64 kW, respectively. Total heat releases of heat detection sensor are in case of alcohol approximately 20.7 MJ and in case of n-heptane approximately 18 MJ, respectively.

Nucleophilic Substitution Reactions of Thiopheneethyl Arenesulfonates with Anilines and N,N-Dimethylanilines

  • 오혁근;윤정환;조인호;이익준
    • Bulletin of the Korean Chemical Society
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    • v.18 no.4
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    • pp.390-394
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    • 1997
  • Nucleophilic substitution reactions of 2-thiopheneethyl benzenesulfonates (2-TEB) and 3-thiopheneethyl benzenesulfonates (3-TEB) with anilines and N,N-dimethylanilines (DMA) are investigated in acetonitrile at 60.0 ℃. The cross-interaction constants ρxz determined for the reactions with anilines are large negative (- 0.50) which are comparable to those for the similar predominantly frontside-attack SN2 reactions of 1-phenylethyl (1-PEB), 2-phenylethyl (2-PEB) and cumyl benzenesulfonates. A large negative ρxz value (- 0.4∼- 0.8) is considered to provide a mechanistic criterion for the frontside-attack SN2 mechanism with a four-center transition state. In agreement with this proposal the kinetic isotope effects, kH/kD, involving deuterated aniline nucleophiles are all greater than one reflecting partial N-H(D) bond cleavage in the transition state. The MO theoretical reactant structures of 1-PEB, 2-PEB and 2-TEB based on the PM3 calculation show that the benzene ring blocks the backside nucleophile approach to the reaction center carbon (Cα) enforcing the frontside-attack SN2 mechanism.

A MEAN VALUE FUNCTION AND ITS COMPUTATIONAL FORMULA RELATED TO D. H. LEHMER'S PROBLEM

  • Wang, Tingting
    • Bulletin of the Korean Mathematical Society
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    • v.53 no.2
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    • pp.487-494
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    • 2016
  • Let p be an odd prime and c be a fixed integer with (c, p) = 1. For each integer a with 1ap1, it is clear that there exists one and only one b with 0bp1 such that abc mod p. Let N(c, p) denote the number of all solutions of the congruence equation abc mod p for 1a, bp1 in which a and ˉb are of opposite parity, where ˉb is defined by the congruence equation bˉb1 mod p. The main purpose of this paper is using the mean value theorem of Dirichlet L-functions and the properties of Gauss sums to study the computational problem of one kind mean value function related to E(c,p)=N(c,p)12ϕ(p), and give its an exact computational formula.

A Study on Development of High Q Active Inductor to be Used in High Frequency Band (높은 주파수대에서 사용 가능한 고품질 능동 인덕터 개발에 관한 연구)

  • 최종은;이상호;박정훈;나극환;박익모;신철재
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.3
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    • pp.445-453
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    • 2000
  • In this paper, the method of designing an active inductor for MMIC is proposed. The proposed tunable active inductor is composed of a cascade FET with feedback capacitors and resistors. Because of a very low series resistance in the proposed inductor, a very high Q factor can be obtained. Also it has an excellent characteristics suitable for high frequency band. The inductance value can be changed by controlling feedback capacitors, resistors and a bias voltage respectively. When the feedback resistor and parallel resistor within circuits are varied, the inductance value is changed from 0.2 nH to 1.7 nH in the range 1 to 15 GHz. Also we designed bandpass filter using the proposed active inductor and it shows the insertion loss of 0.4 dB and return loss, 20 dB.

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Isolated Leptomeningeal Enhancement in Anti-N-Methyl D-Aspartate Receptor Encephalitis: The Diagnostic Value of Contrast-Enhanced Fluid-Attenuated Inversion Recovery Imaging (항-NMDA 수용체 항체와 관련된 뇌염에서 단독 연수막 조영증강: 조영증강 유체감쇠반전회복기법 영상의 진단적 가치)

  • Jun Kyeong Park;Eun Ja Lee;Kwang Ki Kim
    • Journal of the Korean Society of Radiology
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    • v.83 no.4
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    • pp.945-950
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    • 2022
  • Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a common autoimmune encephalitis that is noted to be a severe but treatable disease entity. Patients with anti-NMDAR encephalitis often develop psychotic symptoms, including delusions, hallucinations, and paranoia, as well as memory impairment and persistent loss of attention. However, MRI findings in such patients show no abnormalities in most cases. Although typical brain abnormality features, known as T2 hyperintensities, involve the brain parenchyma and contrast enhancement at the cerebral cortex or overlying meninges, isolated leptomeningeal enhancement has been rarely reported in anti-NMDAR encephalitis. Herein, we report a patient with anti-NMDAR encephalitis who presented with isolated leptomeningeal enhancement, additionally showing the diagnostic value of contrast-enhanced fluid-attenuated inversion recovery imaging.

Temporal and spatial variability in the nutritive value of pasture vegetation and supplement feedstuffs for domestic ruminants in Western Kenya

  • Onyango, Alice Anyango;Dickhoefer, Uta;Rufino, Mariana Cristina;Butterbach-Bahl, Klaus;Goopy, John Patrick
    • Asian-Australasian Journal of Animal Sciences
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    • v.32 no.5
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    • pp.637-647
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    • 2019
  • Objective: The study aimed at quantifying seasonal and spatial variations in availability and nutritive value of herbaceous vegetation on native pastures and supplement feedstuffs for domestic ruminants in Western Kenya. Methods: Samples of herbaceous pasture vegetation (n = 75) and local supplement feedstuffs (n = 46) for cattle, sheep, and goats were collected in 20 villages of three geographic zones (Highlands, Mid-slopes, Lowlands) in Lower Nyando, Western Kenya, over four seasons of one year. Concentrations of dry matter (DM), crude ash (CA), ether extract (EE), crude protein (CP), neutral detergent fibre (NDF), gross energy (GE), and minerals were determined. Apparent total tract organic matter digestibility (dOM) was estimated from in vitro gas production and proximate nutrient concentrations or chemical composition alone using published prediction equations. Results: Nutrient, energy, and mineral concentrations were 52 to 168 g CA, 367 to 741 g NDF, 32 to 140 g CP, 6 to 45 g EE, 14.5 to 18.8 MJ GE, 7.0 to 54.2 g potassium, 0.01 to 0.47 g sodium, 136 to 1825 mg iron, and 0.07 to 0.52 mg selenium/kg DM. The dOM was 416 to 650 g/kg organic matter but differed depending on the estimation method. Nutritive value of pasture herbage was superior to most supplement feedstuffs, but its value strongly declined in the driest season. Biomass yields and concentrations of CP and potassium in pasture herbage were highest in the Highlands amongst the three zones. Conclusion: Availability and nutritive value of pasture herbage and supplement feedstuffs greatly vary between seasons and geographical zones, suggesting need for season- and region-specific feeding strategies. Local supplement feedstuffs partly compensate for nutritional deficiencies. However, equations to accurately predict dOM and improved knowledge on nutritional characteristics of tropical ruminant feedstuffs are needed to enhance livestock production in this and similar environments.

Heat transfer and flow characteristics of a circular jet impinging on a convex curved surface (볼록한 반구면에 충돌하는 원형제트의 열전달 및 유동특성)

  • Lee, Dae-Hui;Jeong, Yeong-Seok;Im, Gyeong-Bin;Kim, Dae-Seong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.4
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    • pp.579-588
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    • 1997
  • The heat transfer and flow measurements from a convex curved surface to a circular impinging jet have been made. The flow at the nozzle exit has a fully developed velocity profile. The jet Reynolds number (Re) ranges from 11,000 to 50,000, the dimensionless nozzle-to-surface distance (L/d) from 2 to 10, and the dimensionless surface curvature (d/D) from 0.034 to 0.089. The results show that the stagnation point Nusselt number (N ust ) increases with increasing value of d/D. The maximum Nusselt number at the stagnation point occurs at L/d .ident. 6 to 8 for all Re's and d/D's tested. For larger L/d, N ust dependency on Re is stronger due to an increase of turbulence in the approaching jet as a result of the more active exchange of momentum with a surrounding air. The local Nusselt number decreases monotonically from its maximum value at the stagnation point. However, for L/d=2 and Re=23,000, and for L/d.leq.4 and Re=50,000, the stream wise Nusselt number distributions exhibit secondary maxima at r/d .ident. 2.2. The formation of the secondary maxima is attributed to an increase in the turbulence level resulting from the transition from a laminar to a turbulent boundary layer.ndary layer.

Nonlinear semigroups on locally convex spaces

  • Hyeon, Son-Kuk
    • East Asian mathematical journal
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    • v.6 no.1
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    • pp.111-121
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    • 1990
  • Let E be a locally convex Hausdorff space and let Γ be a calibration for E. In this note we proved that if E is sequentially complete and a multi-vaiued operaturA in E is Γ-accretive such that D(A)Re (I+λA) for all sufficiently small positive λ, then A generates a nonlinear Γ-contraction semiproup {T(t) ; t>0}. We also proved that if E is complete, Gamma is a dually uniformly convex calibration, and an operator A is m-Γ-accretive, then the initial value problem {ddtu(t)+Au(t)0,t>0,u(0)=x\. has a solution u:[0,)E given by u(t)=T(t)x=lim\limitn(I+tnA)nx each xεD(A).

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Further Results about the Normal Family of Meromorphic Functions and Shared Sets

  • Qi, Jianming;Zhang, Guowei;Zhou, Linlin
    • Kyungpook Mathematical Journal
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    • v.52 no.1
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    • pp.39-47
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    • 2012
  • Let F be a family of meromorphic functions in a domain D, and let k, n(2) be two positive integers, and let S={a1,a2,,an}, where a1, a2, , an are distinct finite complex numbers. If for each fF, all zeros of f have multiplicity at least k+1, f and G(f) share the set S in D, where G(f)=P(f(k))+H(f) is a differential polynomial of f, thenF is normal in D.