• Title/Summary/Keyword: Inexpensive

Search Result 1,273, Processing Time 0.032 seconds

Synthesis of Quinoxaline Derivatives Using TiO2 Nanoparticles as an Efficient and Recyclable Catalyst

  • Alinezhad, Heshmatollah;Tajbakhsh, Mahmood;Salehian, Fatemeh;Biparva, Pourya
    • Bulletin of the Korean Chemical Society
    • /
    • v.32 no.10
    • /
    • pp.3720-3725
    • /
    • 2011
  • $TiO_2$ nanoparticles were synthesized and characterized by SEM and XRD techniques. The $TiO_2$ nanoparticles were employed as a recyclable, inexpensive and efficient catalyst for the synthesis of substituted quinoxalines in high to excellent yields and in relatively short duration.

A New Approach for Built-in Self-Test of 4.5 to 5.5 GHz Low-Noise Amplifiers

  • Ryu, Jee-Youl;Noh, Seok-Ho
    • ETRI Journal
    • /
    • v.28 no.3
    • /
    • pp.355-363
    • /
    • 2006
  • This paper presents a low-cost RF parameter estimation technique using a new RF built-in self-test (BIST) circuit and efficient DC measurement for 4.5 to 5.5 GHz low noise amplifiers (LNAs). The BIST circuit measures gain, noise figure, input impedance, and input return loss for an LNA. The BIST circuit is designed using $0.18\;{\mu}m$ SiGe technology. The test technique utilizes input impedance matching and output DC voltage measurements. The technique is simple and inexpensive.

  • PDF

Metal-Free Oxidation of Alcohols to Their Corresponding Carbonyl Compounds Using NH4NO3/Silica Sulfuric Acid

  • Zarei, Amin
    • Bulletin of the Korean Chemical Society
    • /
    • v.33 no.7
    • /
    • pp.2149-2155
    • /
    • 2012
  • A metal-free and efficient procedure for the oxidation of alcohols into the corresponding carbonyl compounds has been described using ammonium nitrate in the presence of silica sulfuric acid under mild and heterogeneous conditions. The use of non-toxic and inexpensive materials, simple and clean work-up, short reaction times and good yields of the products are among the advantages of this method.

Energy gap measurement of GaAs and $Al_{0-3}Ga_{0-7}As$ using SAW (SAW를 이용한 CaAs 및 $Al_{0-3}Ga_{0-7}As$ 에너지 갭 측정)

  • Park, Nam-Chun;Lee, Kuhn-Il
    • Proceedings of the KIEE Conference
    • /
    • 1987.07a
    • /
    • pp.389-392
    • /
    • 1987
  • The energy gaps of undoped and Cr doped GaAs and $Al_{0-3}Ga_{0-7}As$ was measured nondestructively using surface acoustic wave (SAW) technique. The result is good agreement with other reported result. This technique is inexpensive and simple one for the measurement of mole fraction of $Al_xGa_{1-x}As$.

  • PDF

Finite Raytracing Through Non-rotationally Symmetric Systems (비대칭형 광학계의 유한광선추적)

  • 홍경희
    • Korean Journal of Optics and Photonics
    • /
    • v.1 no.2
    • /
    • pp.217-222
    • /
    • 1990
  • A general ray tracing scheme has been developed for using a personal computer which trace finite rays through any non-rotationally symmetric system. This scheme may be used for the surface type such as conic section with or without aspherics, toric surfaces, sagittal and tangential cylindrical sections and axicons. Specially, any combinational of decentered, tilted and rotated surfaces has been considered. Before transfering to the next surfaces, the local coordinates are refered back to an initial reference coordinate system. We can get a mathmtical model of a non-rotationally symmetrical finite ray trace running on an inexpensive personal computer.

  • PDF

유기태양전지 연구 동향

  • Kim, Gyeong-Gon
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2010.02a
    • /
    • pp.20-20
    • /
    • 2010
  • Organic based photovoltaics (OPV) have been received a lot of attention because they are lightweight, inexpensive to fabricate and flexible compare to crystalline Si solar cells. In this seminar, several important progresses in the Polymer PV, such as, formation of bulk heterojunction, development of post annealing technique, tandem cell fabrication will be introduced. In addition that, some efforts to achieve the further improvement in the performance of the Polymer PV will be discussed.

  • PDF

A Simple Method for the Prepartion of Handmade Blowgun (간편한 Blowgun의 제작법)

  • Shin Sang-Tae
    • Journal of Veterinary Clinics
    • /
    • v.4 no.1
    • /
    • pp.433-438
    • /
    • 1987
  • A cheap, simple, and exact method for the preparation of handmade blowgun was studied. The blowgun-dart-adhesive -stand made of plastic syringe shaft was simple and convenient to make a blowgun dart accuratly. The needle end sealing method with wire-lead(solder) made the needle good to secure and simple to make. Because of easy exchangeability, the tail-piece made of yarn and a rivet is able to use permanently. And the materials of this blowgun were inexpensive, common and easily obtainable. This blowgun dart had various capacity up to 12ml.

  • PDF

An Inexpensive Ant Robot: Basic Concept and Implementation

  • Kubik, Tomasz;Loukianov, Andrey A.
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 2001.10a
    • /
    • pp.36.3-36
    • /
    • 2001
  • Imitating animal behaviors is one of the research projects in robotics. This paper presents basic concepts and implementation of ant robots. Our ant robots refer to the robots that are designed and built by imitating ants´ behaviors. ant robot is 5${\times}$5${\times}$6 cm3. A special feature of our ant robot is low cost, we spend under 30 $US for this project.

  • PDF

Enhanced controlled transdermal release of quinupraqmine from the ethylene-vinyl acetate

  • Shin, Sang-Chul;Kim, Jin;Oh, In-Joon
    • Proceedings of the PSK Conference
    • /
    • 2003.10b
    • /
    • pp.230.1-230.1
    • /
    • 2003
  • In case of oral application of quinupramine, antidepressants, it may cause adverse effects such as diarrhea, nausea due to transient high blood concentration. Ethylene vinyl acetate (EVA) which is heat-processible, flexible, inexpensive material was used for transdermal drug delivery. The purpose of this study was to develop the new transdermal delivery system of quinupramine using EVA polymer matrix that can provide sustained release and avoid the side effects. The EVA matrix containing quinupramine was prepared by solvent-evaporation method. (omitted)

  • PDF

Two-dimensional Oxygen Distribution in a Surface Sediment Layer Measured Using an RGB Color Ratiometric Oxygen Planar Optode (RGB color ratiomatric planar optode로 측정한 표층 퇴적물의 2차원 산소 분포)

  • Lee, Jae Seong;Kim, Eun-Soo;An, Sung-Uk;Kim, Jihye;Kim, Joung-Keun;Khang, Sung-Hyun;Kang, Dong-Jin
    • Ocean and Polar Research
    • /
    • v.35 no.3
    • /
    • pp.229-237
    • /
    • 2013
  • We measured two-dimensional (2-D) oxygen distribution in the surface sediment layer of intertidal sediment using a simple and inexpensive planar oxygen optode, which is based on a color ratiometric image approach. The recorded emission intensity of red color luminophore light significantly changed with oxygen concentration by $O_2$ quenching of platinum(II)octaethylporphyrin (PtOEP). The ratios between the intensity of red and green emissions with oxygen concentration variation demonstrated the Stern-Volmer relationship. The 2-D oxygen distribution image showed microtopographic structure, diffusivity boundary layer and burrow in surface sediment layer. The oxygen penetration depth (OPD) was about 2 mm and the one-dimensional vertical diffusive oxygen uptake (DOU) was 12.6 mmol $m^{-2}d^{-1}$ in the undisturbed surface sediment layer. However, those were enhanced near burrow by benthic fauna, and the OPD was two times deeper and DOU was increased by 34%. The simple and inexpensive oxygen planar optode has great application potential in the study of oxygen dynamics with high spatiotemporal resolution, in benthic boundary layers.