• 제목/요약/키워드: power transition

검색결과 1,036건 처리시간 0.026초

베이비붐세대의 자녀돌봄부담감, 노화불안, 노후준비 및 삶의 질 (Baby Boom Generation's Burden for Taking Care of Children, Aging Anxiety, Preparations for Old Age and Quality of Life)

  • 김정선;강숙
    • 한국보건간호학회지
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    • 제26권3호
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    • pp.440-452
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    • 2012
  • Purpose: The purpose of this study was to provide basic data for use in development of strategy for healthy aging preparation and successful transfer to old age by identifying factors influencing quality of life of the baby boom generation. Methods: The data were collected from a total of 205 members of the baby boom generation(aged 48 to 56), and analysis was performed using descriptive statistics, t-test, ANOVA, Pearson's correlation coefficient, and stepwise multiple regression using the SPSS(Version19.0) program. Results: Burden for taking care of children, aging anxiety, preparations for old age, and quality of life according to the general characteristics and health-related characteristics commonly showed a significant difference in education level and presence of stress. The greater the more burden for taking care of children and the deeper the aging anxiety, the lower the quality of life, and the better prepared for aging, the higher the quality of life. Factors affecting quality of life in the baby boom generation included preparations for old age, burden for taking care of children, monthly household income, and quality of sleep. Explanatory power was 32%. Conclusion: For successful transition to old age and for improvement of quality of life in the baby boom generation, a comprehensive approach in micro and macro dimensions will be sought.

85~115GHz 전파망원경용 컬러게이트 급전 혼 제작 (Fabrication of the Corrugated Feed Horn for 85~115GHz Radio Telescope System)

  • 손태호;한석태
    • 한국전자파학회논문지
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    • 제19권6호
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    • pp.640-646
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    • 2008
  • 밀리미터파 대역에서 동작하는 컬러게이트 혼 안테나의 설계법을 나타낸다. 컬러게이트 혼 설계에 있어서 가장 중요한 하이브리드 조건을 계산한다. 본 논문에서는 파장이 짧은 밀리미터파에서 평형 하이브리드 모드의 변환과 제작이 가능한 크기의 컬러게이트 프로파일을 구한다. 모드 이론을 적용하여 혼 내부 및 컬러게이트 내 전자계를 유도한다. 혼의 전파 특성은 모드 임피던스 정합과 경계 조건으로부터 계산하고, 혼 개구면 전자계로부터 Kirchhoff-Hyugen 원리를 적용하여 방사 전자계를 구한다. $85{\sim}115GHz$ 대역에서 동작하는 밀리미터파 컬러게이트 혼 안테나를 설계하고, 전기 포밍 방식으로 제작한다. 측정 결과, 동작 주파수 대역에서 1.3:1 이하의 VSWR과 주파수 85, 100 및 110 GHz에서 각각 9.2, 9.16 및 9.02도의 반치각이 측정됨으로써 이론적 결과와 잘 부합되고 있음을 보인다.

APR1400의 급수완전상실사고 시 격납건물 내에서 수소와 수증기의 3차원 거동에 대한 수치해석 (NUMERICAL ANALYSIS OF THE HYDROGEN-STEAM BEHAVIOR IN THE APR1400 CONTAINMENT DURING A HYPOTHETICAL TOTAL LOSS OF FEED WATER ACCIDENT)

  • 김종태;홍성환;김상백;김희동
    • 한국전산유체공학회지
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    • 제10권3호
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    • pp.9-18
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    • 2005
  • During a hypothetical severe accident in a nuclear power plant (NPP), hydrogen is generated by the active reaction of fuel-cladding and steam in the reactor pressure vessel and released with steam into the containment. In order to mitigate hydrogen hazards possibly occurred in the NPP containment, hydrogen mitigation system (HMS) is usually adopted. The design of the next generation NPP (APR1400) designed in Korea specifies 26 passive autocatalytic recombiners and 10 igniters installed in the containment for the hydrogen mitigation. in this study, the analysis of the hydrogen and steam behavior during a total lose of feed water (TLOFW) accident in the APR1400 containment has been conducted by using the CFD code GASFLOW. During the accident, a huge amount of hot water, steam, and hydrogen is released in the in-containment refueling water storage tank (IRWST). The current design of the APR1400 includes flap-type dampers at the IRWST vents which are operated depending on the pressure difference between inside and outside of the IRWST. it was found that the flaps strongly affects the flow structure of the steam and hydrogen in the containment. The possibilities of a flame acceleration and transition from deflagration to detonation (DDT) were evaluated by using Sigma-Lambda criteria. Numerical results indicate the DDT possibility could be heavily reduced in the IRWST compartment when the flaps are installed.

차세대 인공위성 전기저항제트 가스추력기의 다물리 수치모사 (MULTI-PHYSICAL SIMULATION FOR THE DESIGN OF AN ELECTRIC RESISTOJET GAS THRUSTER IN THE NEXTSAT-1)

  • 장세명;최진철;한조영;신구환
    • 한국전산유체공학회지
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    • 제21권2호
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    • pp.112-119
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    • 2016
  • NEXTSat-1 is the next-generation small-size artificial satellite system planed by the Satellite Technology Research Center(SatTReC) in Korea Advanced Institute of Science and Technology(KAIST). For the control of attitude and transition of the orbit, the system has adopted a RHM(Resisto-jet Head Module), which has a very simple geometry with a reasonable efficiency. An axisymmetric model is devised with two coil-resistance heaters using xenon(Xe) gas, and the minimum required specific impulse is 60 seconds under the thrust more than 30 milli-Newton. To design the module, seven basic parameters should be decided: the nozzle shape, the power distribution of heater, the pressure drop of filter, the diameter of nozzle throat, the slant length and the angle of nozzle, and the size of reservoir, etc. After quasi one-dimensional analysis, a theoretical value of specific impulse is calculated, and the optima of parameters are found out from the baseline with a series of multi-physical numerical simulations based on the compressible Navier-Stokes equations for gas and the heat conduction energy equation for solid. A commercial code, COMSOL Multiphysics is used for the computation with a FEM (finite element method) based numerical scheme. The final values of design parameters indicate 5.8% better performance than those of baseline design after the verification with all the tuned parameters. The present method should be effective to reduce the time cost of trial and error in the development of RHM, the thruster of NEXTSat-1.

르네상스 이후 20세기에 이르는 여성 헤어스타일의 변천 (Transition of Women's Hairstyles after Renaissance to 20th Century)

  • 이경희
    • 한국의류산업학회지
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    • 제9권1호
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    • pp.15-23
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    • 2007
  • In the Middle Ages it was customary to cover up the hair, but the Renaissance brought uncovered coiffures with the revival of humanism. In those days, silk and linen veil, ribbon, string of pearl used for covering, wrapping round with the hair. During the Baroque period, the style of hair was to pursue the beauty of imbalance in form, reflecting the atmosphere of the time. Hurluberlu and Fontanges hairstyles were in fashion. Then in the Rococo period, huge, resplendent coiffures of exquisite beauty were invented as a symbol of power, and these modes of hairdo were a dominant force in the culture of personal adornment of that time. Pouf and enfant hairstyles were in fashion. As a reaction against the extravagance of the proceding modes, late 18th and early 19th centuries brought revival of simpler hairstyles of ancient Greece and Rome by the influence of neoclassicism. The latter half of the 1820's onwards saw he reappearance of voluminous coiffures as well as an enormous variation of knots with combinations of false knots and chignons. Late 19th through early 20th centuries was the period of beautifully waved hair, the style of which was an integration of Marcel waves and Art Nouveau. The 20th century saw the epoch-making invention of permanent waves using electricity. Concurrently, with an increasing participation of women in social affairs since pre-and post-World War I periods, as well as with Art Deco in full flourish, bobbed hair was created in pursuit of lightness and nimbleness, quickly showing the change of women's modes of life. Hair fashions thoroughly embody the aesthetic sense of each period, reflecting the landscape of contemporary society.

PECVD를 이용한 ZnO박막 증착시 증착 변수가 증착속도 및 결정 구조에 미치는 영향 (The Effects of Deposition Conditions on Deposition Rate and Crystallinity of ZnO Thin Films Deposited by PECVD)

  • 김영진;김형준
    • 한국재료학회지
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    • 제4권1호
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    • pp.90-96
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    • 1994
  • 플라즈마 CVD(PECVFD)장치로 금속유기물인 Diethylzinc와 $N_{2}O$를 합성하여 $300^{\circ}C$이하의 낮은 기판 온도에서 ZnO 박막을 증착하여, 증착변수가 박막의 증착속도 및 결정구조에 미치는 영향을 알아 보았다. 기판 온도 $150^{\circ}C$에서부터 이미 결정화된 ZnO 박막의 증착이 가능했으며, $200^{\circ}C$이상에서 X-ray rocking curve분석결과, 표준편차값($\delta$)이 6˚ 미만의 c축 배향성이 뛰어난 ZnO박막이 유리 기판위에 증착되었다. 기판온도오 인가된 rf전력에 의한 증착속도의 변화 양상은 매우 다양하였으며, 특히 결정화에 따른 증착속도 변화의 전이점이 관찰되었다. 200 W와 250W의 rf 전력에서 증착된 박막의 경우 활성화 에너지는 각각 3.1 KJ/mol과 1.9 KJ/mol이었다.

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Ag-첨가 Ge2Sb2Te5 박막의 물성 및 고속 결정화 (Characteristics of Ag-added Ge2Sb2Te5 Thin Films and the Rapid Crystallization)

  • 김성원;송기호;이현용
    • 한국전기전자재료학회논문지
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    • 제21권7호
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    • pp.629-637
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    • 2008
  • We report several experimental data capable of evaluating the amorphous-to-crystalline (a-c) phase transformation in $(Ag)_x(Ge_2Sb_2Te_5)_{1-x}$ (x = 0, 0.05, 0.1) thin films prepared by a thermal evaporation. The isothermal a-c structural phase changes were evaluated by XRD, and the optical transmittance was measured in the wavelength range of $800{\sim}3000$ nm using a UV-vis-IR spectrophotometer. A speed of the a-c transition was evaluated by detecting the reflection response signals using a nano-pulse scanner with 658 nm laser diode (power P = $1{\sim}17$ mW, pulse duration t = $10{\sim}460$ ns). The surface morphology and roughness of the films were imaged by AFM. It was found that the crystallization speed was so enhanced with an increase of Ag content. While the sheet resistance of c-phase $(Ag)_x(Ge_2Sb_2Te_5)_{1-x}$ was similar to that of c-phase $Ge_2Sb_2Te_5$ (i.e., $R_c{\sim}10{\Omega}/{\square}$), the sheet resistance of a-phase $(Ag)_x(Ge_2Sb_2Te_5)_{1-x}$ was found to be lager than that of a-phase $Ge_2Sb_2Te_5$, $R_a{\sim}5{\times}10^6{\Omega}{/\square}$. For example, the ratios of $R_a/R_c$ for $Ge_2Sb_2Te_5$ and $(Ag)_{0.1}(Ge_2Sb_2Te_5)_{0.9}$ were approximately $5{\times}10^5$ and $5{\times}10^6$, respectively.

Electrical and Thermal Characterization of Organic Varnish Filled with ZrO2 Nano Filler Used in Electrical Machines

  • Selvaraj, D. Edison;Vijayaraj, R.;Sugumaran, C. Pugazhendhi
    • Journal of Electrical Engineering and Technology
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    • 제10권4호
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    • pp.1700-1711
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    • 2015
  • In the last decade it has been witnessed significant developments in the area of nano particles and nano scale fillers on electrical, thermal, and mechanical properties of polymeric materials such as resins, varnishes, enamel and bakelites. The electric and thermal properties were more important in the electrical equipments for both steady state and transient state conditions. This paper deals with the characterization of the electric and thermal properties of the pure varnish and zirconia (ZrO2) filler mixed varnish. The electric properties such as dielectric loss (tan δ), dielectric constant (ε), dielectric strength and partial discharge voltage were analyzed and detailed for different samples. It was observed that zirconia nano filler mixed varnish has the superior dielectric and thermal properties when compared to those of standard varnish. It has shown that at power frequency the 1wt% nano composite sample has the higher permittivity value when compared to other samples. It has been examined that the 1wt% sample was having higher inception and extinction voltages when compared to other samples. It has been observed that 1wt% sample has higher dielectric strength when compared with other samples. There has been an improvement of thermal property by adding few weight percent of zirconia nano fillers. There was not much variation in glass transition among the nano mixed composites. The weight loss was improved at 1wt% of the zirconia nano fillers.

시각적 차원에 의한 건축 공간의 개념 형성에 관한 연구 (A Study on Formation of Concepts of Architectural Space based on the Optical Dimension)

  • 변대중
    • 한국실내디자인학회논문집
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    • 제19권5호
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    • pp.56-66
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    • 2010
  • This study proposes a thesis of architectural concepts and visual dimension systems, and the comparison between steps of spatial formation and dimensional alteration. The second chapter, to form the basis of this study, explains the dimensional alterations and changes of fundamental notion of space. In the third chapter, history of space, architectural formations, and changes of the viewpoint are analyzed as objects of study. The forth chapter presents the interrelation between dimensional alteration and the transition in fundamental notion of space, demonstrating that modern architecture has been born from these cultural movements. Lastly, the fifth chapter suggests possibilities on further studies and the following conclusions: First, architectural spaces have been changed, in accordance with the changes of culture, art and the tools that regulate architectural design. Proportional regulations by two-dimensional tools and depth through three-dimensional drawings are created. Second, architectural spaces gained depth by recognizing movement and time that have induced formations to change, creating various aesthetic backgrounds and attempts. Third, the aesthetic background and cosmologic spatial concept have led the visualization and changes of architectural experience. It created the design tools and shapes originated in dynamism and vitality. Forth, diversification of fundamental spatial concepts has become palimpsest and complex, and been divided into four dimensions; expressional two-dimensional space, perspective three-dimensional space, forth-dimensional space of time and experience, and imagery space formed by body movement. Fifth, architecture has been influenced by the elevated viewpoint that understands the whole world as a space. It has evolved from the two-dimensional proportion principle, change of depth and vanishing point to multidimensional space of movement and time. Sixth, changes of fundamental notion of space have arisen from changes of visual dimensions in times. In other words, space has been developed from two-dimensional space to multidimensional space by accepting visual dimension, grasping distance, direction, depth, height, velocity, movement, gravity, power and structure.

액티브 보조 공진 스너버를 이용한 ZVT-PWM AC-DC 컨버터의 실험적 고찰 (The Experimental Consideration of ZVT-PWM AC-DC Converter using Active Auxiliary Resonant Snubber)

  • 서기영;문상필;김주용;박진민
    • 조명전기설비학회논문지
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    • 제18권2호
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    • pp.75-82
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    • 2004
  • 본 논문에서 액티브 스너버 회로를 가진 영전압 변환 펄스 폭 변조(ZVT-PWM) 컨버터를 제안하였다. 제안된 컨버터는 경부하 상태에서도 동작하며, 영전압 스위칭과 영전류 스위칭 부근에서 온-오프 되며, 주 스위치와 주다이오드에 전압과 전류의 스트레스가 추가적으로 발생하지 않는다. 그리고 보조 스위치와 보조 다이오드의 전압과 전류 허용 레벨을 제시하였다. 제안된 750[W], 80[KHz] PWM 부스터 컨버터는 전 출력 전력에서 소프트 스위칭 컨버터를 적용하여 실행한 결과 주 스위치에서의 손실은 하드 스위칭과 비교해서 약 27[%], 전체 회로 손실은 약 36[%] 저감되었으며, 전체 효율은 기존의 컨버터보다 보다 6{%] 정도 향상됨을 확인하였다.