• Title/Summary/Keyword: the principles of calculation

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A Development of Software about Short-circuit Calculation and Protective-coordination (고장계산 및 보호협조 판정 소프트웨어 개발)

  • Park, S.C.;Choe, J.H.;Seo, J.M.
    • Proceedings of the KIEE Conference
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    • 2002.07a
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    • pp.159-162
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    • 2002
  • A software, called touch-one, is developed about the determination of short-circuit values and protective co-ordination in power system. The used solution algorithm reviewed intensively, and the protective co-ordination determination technique presented by using the circuit-breaker's current-limitation characteristic. The protective coordination concerns the behaviour of two devices placed in series in an electrical network, with a short-circuit downstream circuit-breaker. It has two basic principles: First, discrimination which is an increasing requirement of low voltage electrical distribution systems. Second, which is less well known: cascading, which consists of installing a device, whose breaking capacity is less than the three-phase short-circuit current at its terminals and helped by main circuit-breaker. With this software, we can construct a electric-power system which is reliable and economic according to user's purpose.

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Abacus Numerals for Rapid and Sufficient Mathematics Learning for Enhancing Creativity

  • Hayakawa Yoshinori
    • Research in Mathematical Education
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    • v.9 no.3 s.23
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    • pp.243-256
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    • 2005
  • Abacus numerals were developed using the concept of the binary system to form decimal numerals. This would allow addition, subtraction, multiplication, and division to be performed based solely on the knowledge of the 14 forms of the numerals and three simple rules. These numerals were taught to 260 elementary school pupils of 3rd and 4th grade. After 90 minutes of instruction, they, nearly all, were able to understand principles to add, and to subtract, and partly to multiply using Abacus Numerals. Protected Abacus Numerals are proposed against forgery. An International Numeration System is proposed based on the form of Abacus Numerals to facilitate international communication. A new type of abacus is proposed.

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Spin-polarized energy-gap opening in asymmetric bilayer graphene nanoribbons

  • Kim, Gyu-Bong;Ji, Seung-Hun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.442-442
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    • 2011
  • Electronic and magnetic properties of bilayer zigzag graphene nanoribbon (bZGNR) are studied using pseudopotential density functional method. The edge atoms in the top and bottom layers of bZGNR make a weak hybridization, which leads to electronic structures different from monolayer ZGNR. For asymmetric bZGNR, where the top and bottom layers have different widths, one edge is pinched by the interlayer bonding and the other sustains antiferromagnetic ordering. A small amount of charge transfer occurs from narrower to wider layer, producing spin-polarized electron and hole pockets. External electric field produces asymmetric energy-gap opening for each spin component, inducing half-metallicity in bZGNR.

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Review on the Gas Turbine Combustor Sizing Methodologies using Fuel Atomization and Evaporation Characteristics (연료의 미립화 및 증발 특성 데이터를 이용한 가스터빈 연소기 사이징 기법 고찰)

  • Kim, D.;Jin, Y.I.;Hwang, K.Y.;Min, S.K.
    • Journal of ILASS-Korea
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    • v.19 no.3
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    • pp.101-108
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    • 2014
  • The current paper reviews the main characteristics and the operating principles of major fuel atomizers used for gas turbine combustors, including various empirical SMD equations for each atomizers. We have summarized various methodologies for evaluation of the combustion efficiency and for combustor sizing from the selected SMD data. It is found that the combustor sizing as well as the combustion efficiency are totally dependent upon the SMD calculation results, which means that special cares should be taken in choosing the SMD empirical equations.

Novel Transmission System of 3D Broadcasting Signals using Compressed Sensing (압축 센싱을 이용한 3D 방송 신호 전송 시스템)

  • Lee, Sun Yui;Cha, Jae Sang;Park, Gooman;Kim, Jin Young
    • Journal of Satellite, Information and Communications
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    • v.8 no.4
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    • pp.130-134
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    • 2013
  • This paper describes the basic principles of 3D broadcast system and proposes new 3D broadcast technology that reduce the amount of data by applying CS(Compressed Sensing). Differences between Sampling theory and the CS technology concept was described. Recently proposed CS algorithm AMP(Approximate Message Passing) and CoSaMP(Compressive Sampling Matched Pursuit) was described. Image data that compressed and restored by these algorithm was compared. Calculation time of the algorithm having a low complexity is determined.

Sampling Techniques for Wireless Data Broadcast in Communication (통신에서의 무선 데이터 방송을 위한 샘플링 기법)

  • Lee, Sun Yui;Park, Gooman;Kim, Jin Young
    • Journal of Satellite, Information and Communications
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    • v.10 no.3
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    • pp.57-61
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    • 2015
  • This paper describes the basic principles of 3D broadcast system and proposes new 3D broadcast technology that reduces the amount of data by applying CS(Compressed Sensing). Differences between Sampling theory and the CS technology concept was described. CS algorithm SS-CoSaMP(Single-Space Compressive Sampling Matched Pursuit) and AMP(Approximate Message Passing) was described. Image data compressed and restored by these algorithm was compared. Calculation time of the algorithm having a low complexity is determined.

Development of the Computer-Assisted HACCP System Program and Developing HACCP-Based Evaluation Tools of Sanitation for Institutional Foodservice Operations (단체급식의 HACCP 전산프로그램 및 위생관리 평가도구 개발)

  • 이정숙;홍희정;곽동경
    • Korean Journal of Community Nutrition
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    • v.3 no.4
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    • pp.655-667
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    • 1998
  • The Computer-assisted Hazard Analysis and Critical Control Point(HACCP) program has been developed for a systematic implementation of HACCP principles in identifying, assessing and controlling hazards in institutional foodservics operations. The HACCP-based sanitation evaluation tool has been developed, based on the results of the computerized assisted HACCP program in 4 service sites of C contracted foodservice company, including 2 general hospitals with 650-beds, one office operation of 400 meals per day, and one factory foodservice of 1,000 meals per day. All database files and processing programs were created by using Unify Vision tool with Windows 95 of user environments. The results of this study can be summarized as follows : 1. This program consists of the pre-stage for HACCP study and the implementation stage of the HACCP system. 1) The pre-stage for HACCP study includes the selection of menu items, the development of the HACCP recipe, the construction of product flow diagrams, and printing the HACCP recipes and product flow diagrams. 2) The implementation of the HACCP system includes the identification of microbiological hazards, the determination of critical control points based on the decision tree base files. 3) The HACCP-based sanitation evaluation tool consisted of 3 dimensions of time-temperature relationship, personal hygiene, and equipment-facility sanitation. The Cronbach's alphas calculation indicated that the tool was reliable. The results showed that the focus groups rated the mean of importance in time-temperature relationship, personal hygiene, and equipment-facility sanitation as 4.57, 4.59 and 4.55 respectively. Based on the results, this HACCP-based sanitation evaluation tool was considered as an effective tool for assuring product quality. This program will assist foodservice managers to encourage a standardized approach in the HACCP study and to maintain a systematic approach for ensuring that the HACCP principles are applied correctly.

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Effect of Transition Metal Dopant on Electronic State and Chemical Bonding of MnO2 (MnO2의 전자상태 및 화학결합에 미치는 천이금속 첨가의 효과)

  • 이동윤;김봉서;송재성;김양수
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.7
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    • pp.691-696
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    • 2004
  • The electronic state and chemical bonding of $\beta$-MnO$_2$ with transition metal dopants were theoretically investigated by DV-X$_{\alpha}$ (the discrete variational X$_{\alpha}$) method, which is a sort of the first principles molecular orbital method using the Hartree-Fock-Slater approximation. The calculations were performed with a $_Mn_{14}$ MO$_{56}$ )$^{-52}$ (M = transition metals) cluster model. The electron energy level, the density of states (DOS), the overlap population, the charge density distribution, and the net charges, were calculated. The energy level diagram of MnO$_2$ shows the different band structure and electron occupancy between the up spin states and down spin states. The dopant levels decrease between the conduction band and the valence band with the increase of the atomic number of dopants. The covalency of chemical bonding was shown to increase and ionicity decreased in increasing the atomic number of dopants. Calculated results were discussed on the basis of the interaction between transition metal 3d and oxygen 2p orbital. In conclusion it is expected that when the transition metals are added to MnO$_2$ the band gap decreases and the electronic conductivity increases with the increase of the atomic number of dopants. the atomic number of dopants.

Variation of the Si-induced Gap State by the N defect at the Si/SiO2 Interface

  • Kim, Gyu-Hyeong;Jeong, Seok-Min
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.128.1-128.1
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    • 2016
  • Nitrided-metal gates on the high-${\kappa}$ dielectric material are widely studied because of their use for sub-20nm semiconductor devices and the academic interest for the evanescent states at the Si/insulator interface. Issues in these systems with the Si substrate are the electron mobility degradation and the reliability problems caused from N defects that permeates between the Si and the $SiO_2$ buffer layer interface from the nitrided-gate during the gate deposition process. Previous studies proposed the N defect structures with the gap states at the Si band gap region. However, recent experimental data shows the possibility of the most stable structure without any N defect state between the bulk Si valence band maximum (VBM) and conduction band minimum (CBM). In this talk, we present a new type of the N defect structure and the electronic structure of the proposed structure by using the first-principles calculation. We find that the pair structure of N atoms at the $Si/SiO_2$ interface has the lowest energy among the structures considered. In the electronic structure, the N pair changes the eigenvalue of the silicon-induced gap state (SIGS) that is spatially localized at the interface and energetically located just above the bulk VBM. With increase of the number of N defects, the SIGS gradually disappears in the bulk Si gap region, as a result, the system gap is increased by the N defect. We find that the SIGS shift with the N defect mainly originates from the change of the kinetic energy part of the eigenstate by the reduction of the SIGS modulation for the incorporated N defect.

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First-Principles Study on the Magnetism and Electronic Structure of Fe Nanostripes (나노 구조 철띠의 자성과 전자구조에 대한 제일원리 연구)

  • Byun, Y.;Lee, J.I.
    • Journal of the Korean Magnetics Society
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    • v.16 no.5
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    • pp.229-233
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    • 2006
  • We investigated the magnetic properties of Fe nanostripes by using the all electron full-potenial linearized augmented plane-wave (FLAPW) energy band method within the generalized gradient approximation (GGA). The magnetic moments of the Fe atoms in the edge Fe chains of the stripes composed of three, five, and seven chains have saturated values of 2.97 or 2.98 ${\mu}_B$, and the values of the center chains are 2.82 ${\mu}_B$ which is similar to that of 2D square lattice. The charge and spin density contour plots showed that the flat distribution in the edge region of the stripes, and it is due to the spilled out p-electrons from the atoms in the edge line. The calculated density of states for the edge atoms in the stripes with seven Fe chains showed that the narrowed width compared to that of center atoms due to the band narrowing effect at the edge.