• Title/Summary/Keyword: k Out of n

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Corrosion Characteristics of TiN and ZrN Coated Orthodontic Brackets (TiN 및 ZrN 코팅된 교정용 브라켓의 부식특성)

  • Kim, W.G.;Kim, D.Y.;Choe, H.C.
    • Journal of Surface Science and Engineering
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    • v.41 no.4
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    • pp.163-168
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    • 2008
  • The dental orthodontic bracket requires good mechanical properties, such as elastic strength and frictional resistance, combined with a high resistance to corrosion. The objective of this study was to investigate the effects of TiN and ZrN coating on corrosion resistance of orthodontic brackets using various electrochemical methods. Brackets manufactured by Ormco Co. were used, respectively, for experiment. Ion plating was carried out for coatings of bracket using Ti and Zr coating materials with nitrogen gas. Ion plated surface of each specimen was observed with field emission scanning electron microscopy(FE-SEM), energy dispersive Xray spectroscopy(EDS) and electrochemical tester. The corrosion potential of the TiN and ZrN coated bracket was comparatively high. The current density of TiN and ZrN coated bracket was smaller than that of non-coated bracket in 0.9% NaCl solution. Pit nucleated at angle of bracket slot.

Interband optical properties in wide band gap group-III nitride quantum dots

  • Bala, K. Jaya;Peter, A. John
    • Advances in nano research
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    • v.3 no.1
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    • pp.13-27
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    • 2015
  • Size dependent emission properties and the interband optical transition energies in group-III nitride based quantum dots are investigated taking into account the geometrical confinement. Exciton binding energy and the optical transition energy in $Ga_{0.9}In_{0.1}N$/GaN and $Al_{0.395}In_{0.605}N$/AlN quantum dots are studied. The largest intersubband transition energies of electron and heavy hole with the consideration of geometrical confinement are brought out. The interband optical transition energies in the quantum dots are studied. The exciton oscillator strength as a function of dot radius in the quantum dots is computed. The interband optical absorption coefficients in GaInN/GaN and AlInN/AlN quantum dots, for the constant radius, are investigated. The result shows that the largest intersubband energy of 41% (10%) enhancement has been observed when the size of the dot radius is reduced from $50{\AA}$ to $25{\AA}$ of $Ga_{0.9}In_{0.1}N$/GaN ($Al_{0.395}In_{0.605}N$/AlN) quantum dot.

MOCVD of GaN Films on Si Substrates Using a New Single Precursor

  • Song, Seon-Mi;Lee, Sun-Sook;Yu, Seung-Ho;Chung, Taek-Mo;Kim, Chang-Gyoun;Lee, Soon-Bo;Kim, Yun-Soo
    • Bulletin of the Korean Chemical Society
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    • v.24 no.7
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    • pp.953-956
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    • 2003
  • Hexagonal GaN (h-GaN) films have been grown on Si(111) substrates by metal organic chemical vapor deposition using the azidodiethylgallium methylamine adduct, Et₂Ga(N₃)·NH₂Me, as a new single precursor. Deposition was carried out in the substrate temperature range 385-650 °C. The GaN films obtained were stoichiometric and did not contain any appreciable amounts of carbon impurities. It was also found that the GaN films deposited on Si(111) had the [0001] preferred orientation. The photoluminescence spectrum of a GaN film showed a band edge emission peak characteristic of h-GaN at 378 nm.

Hydrodynamic Resistance of Some Trawl Nets Being Used by M/S Saebada (새바다호에서 사용하는 트로올그물의 유체저항에 관하여)

  • KIM Jin-Kun
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.17 no.1
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    • pp.1-8
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    • 1984
  • The author carried out an experiment to determine the resistance of trawl net aboard M/S Saebada, training ship of National Fisheries University of Pusan, 2,275 G/T and 3,600ps. Total tension loaded on warp were measured by the recording tension meter. Resistance of the net is estimated by subtracting the resistance of otter boards and warps from the total tension. Coefficient k and exponent n of the formula on the trawl net deduced by Koyama, $R_N=k\frac{d}{l}abv^n$ were calculated from the resistance of the net obtained. The results obtained are can be summarized as follows : 1. Six seamed net with two net pendant k=11, n=1.8 2. Eight seamed net with three net pendant k=11, n=1.8 3. Ten seamed net with three net pendant k=9, n=1.9 4. Ten seamed net with four net pendant k=9, n=1.9

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A Selective Oxidation of Tetraline by Chromium (VI) Compounds (I) (Cr (VI) 촉매에 의한 Tetraline 의 선택적 산화반응 (I))

  • Sun-Kun Bae;Sang-Bong Lee;Dae-Chul Park;Kyu-Wan Lee
    • Journal of the Korean Chemical Society
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    • v.33 no.1
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    • pp.106-112
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    • 1989
  • Liquid phase oxidation of tetralin with clean air were carried out utilizing complexes composed of various heterocyclic base and CrO$_3$ in N,N-dialkylamides. In the CrO$_3$-N,N-dialkylacetamide complex catalyzed oxidations of tetralin at 90$^{\circ}$C, the maximum conversion of tetralin to the products and selectivity of ${\alpha}$-tetralone were 35.2% and 96.1%, respectively. Under this condition, however, negligible amount of ${\alpha}$-tetralol was determined.

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An Adaptive Learning Rate with Limited Error Signals for Training of Multilayer Perceptrons

  • Oh, Sang-Hoon;Lee, Soo-Young
    • ETRI Journal
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    • v.22 no.3
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    • pp.10-18
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    • 2000
  • Although an n-th order cross-entropy (nCE) error function resolves the incorrect saturation problem of conventional error backpropagation (EBP) algorithm, performance of multilayer perceptrons (MLPs) trained using the nCE function depends heavily on the order of nCE. In this paper, we propose an adaptive learning rate to markedly reduce the sensitivity of MLP performance to the order of nCE. Additionally, we propose to limit error signal values at out-put nodes for stable learning with the adaptive learning rate. Through simulations of handwritten digit recognition and isolated-word recognition tasks, it was verified that the proposed method successfully reduced the performance dependency of MLPs on the nCE order while maintaining advantages of the nCE function.

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Improved analytical formulation for Steel-Concrete (SC) composite walls under out-of-plane loads

  • Sabouri-Ghomi, Saeid;Nasri, Arman;Jahani, Younes;Bhowmick, Anjan K.
    • Steel and Composite Structures
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    • v.38 no.4
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    • pp.463-476
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    • 2021
  • The concept of using Steel-concrete (SC) composite walls as retaining walls has recently been introduced by the authors and their effectiveness of resisting out-of-plane loads has also been demonstrated. In this paper, an improved analytical formulation based on partial interaction theory, which has previously been developed by the authors, is presented. The improved formulation considers a new loading condition and also accounts for cracking in concrete to simulate the real conditions. Due to a limited number of test specimens, further finite element (FE)simulations are performed in order to verify the analytical procedure in more detail. It is observed that the results from the improved analytical procedure are in excellent agreement with both experimental and numerical results. Moreover, a detailed parametric study is conducted using the developed FE model to investigate effects of different parameters, such as distance between shear connectors, shear connector length, concrete strength, steel plate thickness, concrete cover thickness, wall's width to thickness ratio, and wall's height to thickness ratio, on the behavior of SC composite walls subjected to out-of-plane loads.

Bending Behavior of Nailed-Jointed Cross-Laminated Timber Loaded Perpendicular to Plane

  • Pang, Sung-Jun;Kim, Kwang-Mo;Park, Sun-Hyang;Lee, Sang-Joon
    • Journal of the Korean Wood Science and Technology
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    • v.45 no.6
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    • pp.728-736
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    • 2017
  • In this study, the bending behavior of cross-laminated timber (CLT) connected by nails were investigated. Especially, the load-carrying capacity of the nail-jointed CLT under out-of-plane bending was predicted by the lateral resistance of the used nails. Three-layer nail-jointed CLT specimens and a nail connection were manufactured by 30 mm (thickness) ${\times}$ 100 mm (width) domestic species (Pinus koraiensis) laminas and Ø$3.15{\times}82mm$ nails using a nail-gun. Shear test for evaluating the nail lateral resistance and bending test for evaluating the load-carrying capacity of the nail-jointed CLT under out-of-plane bending were carried out. As a result, two lateral resistance of the used nail, the 5% fastener offset value and the maximum value, were 913 N and 1,534 N, respectively. The predicted load-carrying capacity of the nail-jointed CLT by the 5% offset nail lateral resistance was similar to the yield points on the actual load-displacement curve of the nail-jointed CLT specimens. Meanwhile, the nail-jointed CLT specimens were not failed until the tension failure of the bottom laminas occurred beyond the maximum lateral resistance of the nails. Thus, the measured maximum load carrying capacities of the nail-jointed CLT specimens, approximately 12,865 N, were higher than the predicted values, 7,986 N, by the maximum nail lateral resistance. This indicates that the predicted load-carrying capacity can be used for designing a structural unit such as floor, wall and roof able to support vertical loads in a viewpoint of predicting the actual capacities more safely.

Growth properties of Neolentinus lepideus according to the light environment (광환경에 따른 잣버섯의 생육특성)

  • Jang, Myoung-Jun;Lee, Yun-Hae;Cho, Yong-Koo;Koo, Han-Mo;Oh, Tae-Seok
    • Journal of Mushroom
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    • v.13 no.2
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    • pp.125-128
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    • 2015
  • We found about cultivation light environment conditions of Neolentinus lepideus. For the high quality of N. lepideus, lights-out was useful. In the lights-out, the diameter of pileus of N. lepideus was smaller, and the length and the thickness of stipes were longer and larger than in that of lighting. At the LED effect, the orange and red LEDs prolonged the cultivation period in N. lepideus. The yields of N. lepideus under the white, blue and green LEDs were higher, and the number of available stipes of N. lepideus under the white and blue LEDs was higher than that of other LEDs. The diameter of pileus of N. lepideus under the white, blue and green LEDs was higher, and the length and the thickness of stipes under the orange and red LEDs was higher than those of other LEDs.

A Study on Fluid Dynamics for Effect of Agitation Velocity on Nutrients Removal in High Rate Algae Stabilization Pond (고율 조류 안정화지에서 교반속도가 영양염류 제거에 미치는 영향에 관한 유체동역학적 연구)

  • 공석기
    • Journal of Environmental Science International
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    • v.10 no.1
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    • pp.65-71
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    • 2001
  • HRP(high rate pond) which had kept the manufactured clay of 3cm-thickness as benthic clay in reactor and the 6 flat-blade turbine as impeller for agitation was named HRASP(high rate algae stabilization pond). And the experiment for treatment of artificial synthesis wastewater containing COD :300mg/$\ell$, NH$_3$-N : 300mg/$\ell$, T-P : 9mg/$\ell$ as nutrients was been performed successfully. This reactor was been operated under conditions : 24hrs.-irradiation and water temperature, $25^{\circ}C$ and pH 7 and agitation velocity, 15, 30, 45rpm and the effect of agitation velocity on algal bioaccumulation of nutrients was been studied with view point of fluid dynamics. The next followings could be obtained as results. 1. The agitation with a turbine impeller blade in HRASP makes clay particle indicate superior suspension effect by means of forming of excellent curl/shear flow in reactor. 2. The excessive suspension of clay particle which is created at 45rpm as rotation velocity of impeller blade of turbine disturbs the light penetration and algal photosynthesis reaction. 3. Efficiencies for removal of nutrients come out as COD : 93.9%~94.3%, ($NH_3-N + NO_3-N$) : 81.9%~99.0%, T-P : 46.8%~53.6%. 4. Kuo values of $K_1$for algal growth come out seperately as 15rpm : $1.876{\times}10^{-2}, 30rpm : 4.618{\times}10^{-3}$. 5. Kuo values of $K_2$for removal of N, P come out seperately as 15rpm : $8.403{\times}10^{-1}$ and $1.397{\times}10^{-1}$, 30rpm : $4.823{\times}10^{-1} and 2.052{\times}10^{-1}$. 6. It can be guessed easily that the excessive agitation can inhibit the algal and bacterial symbiotic reaction if it is considered that micro organism\` sense to preservation of life is relied on natural function of metabolism. Therefore the studies for this matter should be followed continuously.

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