• Title/Summary/Keyword: penetration enhancement

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Low-voltage cathodoluminescent Characteristics of ZnGa$_2$O$_4$ : Mn phosphors

  • 조성희;유재수;이종덕;이중환
    • Journal of the Korean institute of surface engineering
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    • v.30 no.1
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    • pp.57-62
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    • 1997
  • Green-emitting $ZnGa_2O_4$ : Mn phosphors were synthesized by a thermal method and their low-voltage cathodoluminescent characteristics were examined for the field emitter display (FED) application. Low efficiency of $ZnGa_2O_4$ : Mn phosphors could be ascribed to the low penetration depth of into phosphors, which might results in charge accumulation on the phosphors screen. For increasing cathodoluminescent of $ZnGa_2O_4$ : Mn under low voltage excitation, wide band-gap oxide materials were added to the $ZnGa_2O_4$: Mn powder. It is found that the luminance can be increased by 20%. Measurement of leakage current on the phosphor screen shows that the enhancement of low-voltage cathodoluminescent by additive materials is mainly due to the consumption of surface charges on the phosphor.

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A Study on the Enhancement of Ultrasonic Signal Recognition in Ferrite Carbon Steel Weld Zone Using Neural Networks (신경회로망을 이용한 페라이트계 탄소강 용접부의 초음파 신호 인식 향상에 관한 연구)

  • Yun, In-Sik;Park, Won-Kyou;Yi, Won
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.1
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    • pp.158-164
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    • 2002
  • This paper proposes the optimization of ultrasonic signal recognition in ferrite carbon steel weld zone using neural networks. For these purposes, the ultrasonic signals for defects as porosity, incomplete penetration and slag inclusion in the weld zone are acquired in the type of time series data. And then their applications evaluated feature extraction based on the time-frequency-attractor domain(peak to peak, rise time, rise slope, fall time, fall slope, pulse duration, power spectrum, and bandwidth) and attractor characteristics (fractal dimension and attractor quadrant) etc. The proposed neural networks system in this study can enhances performance of ultrasonic signal recognition.

Resonance Characteristics of THz Metamaterials Based on a Drude Metal with Finite Permittivity

  • Jun, Seung Won;Ahn, Yeong Hwan
    • Current Optics and Photonics
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    • v.2 no.4
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    • pp.378-382
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    • 2018
  • In most previous investigations of plasmonic and metamaterial applications, the metallic film has been regarded as a perfect electrical conductor. Here we demonstrate the resonance characteristics of THz metamaterials fabricated from metal film that has a finite dielectric constant, using finite-difference time-domain simulations. We found strong redshift and spectral broadening of the resonance as we decrease the metal's plasma frequency in the Drude free-electron model. The frequency shift can be attributed to the effective thinning of the metal film, originating from the increase in penetration depth as the plasma frequency decreases. On the contrary, only peak broadening occurs with an increase in the scattering rate. The metal-thickness dependence confirms that the redshift and spectral broadening occur when the effective metal thickness drops below the skin-depth limit. The electromagnetic field distribution illustrates the reduced field enhancement and reduced funneling effects near the gap area in the case of low plasma frequency, which is associated with reduced charge density in the metal film.

Optimization of Surface Treatment System for Concrete Structures to Control Chloride Penetration (콘크리트 구조물용 표면도장공법의 차염성능의 최적화에 대한 연구)

  • Lee Chang-Soo;Sung Jae-Duk;Yoon In-Seok
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.11a
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    • pp.233-236
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    • 2004
  • The purpose of this paper is to evaluate performance on reducing the chloride diffusion of surface treatment systems with elapsed time, treatment thickness, treatment frequency, and the types of surface treatment - coating, penetrator, and both all. Based on this paper, the guideline to applicate surface treatment systems will be established and comprehended how effective the resistance of chloride diffusion is. The selection of surface treatment materials and thickness to acquire service life of target will be possible. It is also expected to select optimum surface treatment system groups to resist chloride diffusion effectively and to estimate increased service life as the effect of durability enhancement.

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The Improvement on Insulation Performance of Underground Distribution Power Cables (지중배전케이블 절연성능 향상 방안)

  • Lee, Jae-Bong;Lee, Byung-Sung;Kim, Sang-Joon;Jang, Sang-Ok;Han, Yong-Huei;Oh, Jae-Hyoung
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2004.05a
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    • pp.497-501
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    • 2004
  • The primary failure causes of underground distribution power cables are water penetration in insulation layer and stress enhancement at inner semi-conductive layer. Accordingly, it is needed to improve the materials and the structure of power cables for extending lifetime and preventing failure. We uses non-flaming PE materials instead of PVC as a covering material and encapsulating structure. We also use super smooth class material as a inner semi-conductive layer. The newly developed cables are improved in AC breakdown voltage after ageing tests.

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Synthesis and Application of Reactive Polymer Modifiers for Asphalt: 2. Application (아스팔트용 반응성 고분자 개질제 합성 및 적용: 2. 적용)

  • Hwang, Ki-Seob;Lee, Jong-Cheol;Jang, Suck-Soo;Lee, Seung-Han;Ha, Ki-Ryong
    • Polymer(Korea)
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    • v.31 no.6
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    • pp.538-542
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    • 2007
  • This study is on the performance analysis of modified asphalts which were prepared by mixing the asphalt with polymer modifiers of varying compositions which were synthesized by the emulsion polymerization method. Thermal properties of mired asphalt were investigated by DSC (differential scanning calorimetry), and dispersion of modifiers in asphalt was investigated by the fluorescence microscope. Dynamic stability and permanent deformation velocities of mixed asphalt were investigated by wheel tracking measurements. Modifier 6 showed the best results in both penetration test and wheel tracking measurement among investigated modifiers, which supports MMA(methyl methacrylate) moiety in modifiers plays better contribution for the enhancement of asphalt performance than styrene moiety does.

Enhancement of the Stability and Skin Penetration of Vitamin C by Polyphenol (폴리페놀의 비타민 C 안정성 유지와 피부 침투성 증가에 관한 연구)

  • Kang, Jae Seung;Cho, Daeho;Lee, Wang Jae
    • IMMUNE NETWORK
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    • v.4 no.4
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    • pp.250-254
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    • 2004
  • Background: It is necessary for human beings to uptake vitamin C through diet or supplements. It is also well-known that vitamin C plays an important role in the prevention of scurvy, enhancement of collagen synthesis and anti-tumor immune response. In addition, there are several recent reports regarding the effective role of vitamin C on the regulation of allergic responses, such as atopic dermatitis and asthma. However, the effective therapeutic and preventive measures using vitamin C are not established yet, since vitamin C is seriously unstable in aqueous solution. Therefore, we have investigated the best way to maintain the stability of vitamin C. Methods: After we making a mixture of polyphenol (0.001, 0.01, 0.1%) and vitamin C (1 mM), the mixtures were placed at room temperature both with/without light protection. And then the concentration of ascorbic acid was measured with HPLC. To analyze the in vivo effect of vitamin C on the regulation of skin allergic reaction, polyphenol (0.1%)-vitamin C (1 mM) mixture was applied to the skin and the production of histamine from mast cell was analyzed by Evans blue dye staining. Results: We have found that the polyphenol has preventive power of oxidation of vitamin C. In addition, the production of histamine was suppressed by the polyphenol (0.1%)-vitamin C (1 mM) mixture. Conclusion: We have reached the conclusion that our study suggests the research guideline for the therapy of atopic dermatitis through vitamin C.

Effect of the Fineness of Fly Ash on the Compressive Strength (플라이애시 입도가 압축강도에 미치는 영향)

  • Cho, Young-Keun;Kim, Ho-Kyu;Kim, Young-Ahn
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.5 no.3
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    • pp.313-319
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    • 2017
  • In general, various factors such as grain size, chemical composition, amorphous amount, amorphous Si and Al content of fly ash affect the reaction with cement. In this study, we investigate the effect of fly ash particle characteristics on compressive strength. The standard sand was pulverized to a particle size similar to that of fly ash and the compressive strength was measured by blending with the cement as in fly. Using the measured compressive strength results, strength enhancement by cement hydration reaction and strength enhancement by particle filling effect were confirmed. Strength increment by pozzolanic reaction of fly ash was calculated by using the compressive strength results of mortar substituted with standard powder. As a result of comparison between compressive strengths and the particle characteristics of fly ash, the blaine showed a weak correlation with the compressive strength and the PI(Pozzolanic Index) showed good correlation with the 10% penetration diameter(D10) and the 50% Respectively. Therefore, it is expected that PI will be a good means to evaluate the fly ash characteristics together with the chemical characteristics of fly ash.

New Drug Delivery System Based on a Laser-Induced Shockwave (레이저 유도 충격파를 이용한 첨단 약물전달시스템 개발)

  • Han, Tae-Hee;Lee, Hyun-Hee;Gojani, Ardian B.;Yoh, Jai-Ick
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.1
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    • pp.67-71
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    • 2010
  • Impingement of a high power laser pulse (above 1 GW/$cm^2$) on a metal foil causes its ablation, which is characterized by a rapid expulsion of matter and the initiation of a strong shock wave inside the solid metal. The shock propagates through the foil and reverberates on the rear side, causing its deformation and microparticle ejection, which were deposited on the foil prior to ablation. Based on this principle, we are developing a new drug delivery system - Biolistic gun. Current study is focused on the controllability, stability, efficiency of the system, and characterization of the penetration shapes in various conditions. We have tested the system by applying direct and confined ablation. Several different media combinations were used for confinement-BK7 glass, water, BK7 glass with water, and succulent jelly(ultrasono jelly, RHAPAPHRM). Biological tissue was replicated by a 3% gelatin solution. Present data shows that the confinement results in enhancement of penetration shape reached by 5 um cobalt microparticles. Based on the analysis of the experimental results we observe that the penetration shape of microparticles can be controlled by adjusting the thickness of confinement media.

Enhanced Permeation of Leucine Enkephalin and [D-Ala2]-leucine Enkephalinamide across Nasal, Rectal and Vaginal Mucosae of Rabbit (토끼의 비강, 직장 및 질 점막을 통한 로이신엔케팔린과 [D-알라2]-로이신엔케팔린아미드의 투과 증진)

  • 전인구;박인숙;곽혜선
    • Biomolecules & Therapeutics
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    • v.10 no.2
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    • pp.104-113
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    • 2002
  • The effects of enzyme inhibitors and penetration enhancers on the permeation of leucine enkephalin (Leu-Enk) and its synthetic analog, [${D-ala}^2$]-leucine enkephalinamide (YAGFL) across the nasal, rectal and vaginal mucosae were evaluated. Enzyme inhibitors and penetration enhancers employed for Leu-Enk permeation study were amastatin(AM), thimerosal(TM) and ethylenediaminetetraacetic acid disodium salt(EDTA), and sodium taurodihydrofusidate (STDHF). Those for YAGFL permeation study were TM, benzalkonium chloride(BC) and EDTA, and STDHF, sodium deoxycholate(SDC), sodium glycholate(SGC), glycyrrhizic acid ammonium salt (GAA), L-$\alpha$-Iysophosphatidylcholine(LPC) and mixed micelle (MM, STDHF: linoleic acid = 15 mM : 5 mM). The addition of TM alone on the donor and receptor solutions for Leu-Enk permeation study across all the three kinds of mucosae failed to inhibit the degradation; it completely degraded in 6 hrs, and no permeation occurred. However, with addition of three kinds of inhibitors together, the fluxes across nasal, rectal and vaginal mucosae were $\20.7{pm}2.5$>/TEX>,$\0.3{pm}0.05$>/TEX> and $\1.4{pm}0.5$ $\mu$\mid$textrm{m}$/$\textrm{cm}^2$/hr, respectively. Moreover, the addition of STDHF in the presence of the above three inhibitors enhanced permeation across nasal, rectal and vaginal mucosae 1.3, 15 and 1.3 times, respectively. YhGFL also degraded in the donor and receptor solutions rapidly as time went. With mixed inhibitors of TM and EDTA, the percents of YAGFL remaining in the donor solutions facing nasal, rectal and vaginal mucosae were 69.7, 69.8 and 79.8%, respectively; the percent permeated increased to 10, 2.1 and 5.7%, respectively. The addition of STDHF in the presence of either BC/EDTA or TW/EDTA increased the permeation 2.2, 11.0 and 2.9 times, and 2.21, 14.0 and 2.7 times for nasal, rectal and vaginal mucosae, respectively. With SDC, SGC, GAA, LPC ud MM in the presence of TM/EDTA increased permeation; especially, they increased permeation across vaginal mucosae effectively, and the enhancement factors were 12.5, 7.6, 8.7, 5.7 and 5.5, respectively. The degradation extent of YAGFL was correlated with protein concentrations in the epidermal and serosal extracts. The flux of YAGFL across nasal mucosa increased dose-dependently.