• 제목/요약/키워드: Induced Current Density

검색결과 338건 처리시간 0.031초

유입하천 밀도와 계절별 수온을 고려한 팔당호 성층 해석 (Stratified features in Paldang lake considering induced density currents and seasonal thermal effect)

  • 최수인;김동수;서일원
    • 한국수자원학회논문집
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    • 제57권2호
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    • pp.99-110
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    • 2024
  • 팔당호 취수장은 수도권 주민에게 상수원을 공급하는 주요 취수장으로, 상수원의 수질 관리를 위해 국가 차원에서 노력을 기울이고 있다. 팔당댐 취수장 인근의 수심이 가장 깊은 지역은 여름철에 연직 방향으로 성층이 발견되는데, 성층의 원인이 밀도류에 의한 것인지 여름철 기온에 의한 것인지 명확하게 분류하기 어려운 실정이다. 본 연구에서는 팔당호 주요 지점의 연직 수질 측정을 통해 밀도류에 의한 성층과 기온에 의한 성층을 분류하고, 발생 원인을 분석하였다. 연구 결과로는 밀도류와 기온에 의한 성층을 구분하였으며, 밀도류의 형성은 유입 하천 간 수온 차이에서 기인하는 것으로 확인되었지만, 밀도류의 지속 거리는 유속에 크게 의존하는 것으로 나타났다. 또한, 갈수기와 풍수기 혼합 특성을 기반으로 하천형과 호소형 특성을 가진 지역으로 팔당호를 분류하였다.

해석적 방법을 이용한 슬롯리스 양측식 코어드 타입 영구자석 발전기의 와전류 손실 해석 (Eddy Current Loss Analysis of Slotless Double-sided Cored Type Permanent Magnet Generator by using Analytical Method)

  • 장강현;정경훈;홍기용;김경환;최장영
    • 전기학회논문지
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    • 제65권10호
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    • pp.1639-1647
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    • 2016
  • This paper deals with eddy current loss analysis of Slotless Double sided Cored type permanent magnet linear generator by using analytical method, space harmonic method. In order to calculate eddy current, this paper derives analytical solution by the Maxwell equation, magnetic vector potential, Faraday's law and a two-dimensional(2-D) cartesian coordinate system. First, we derived the armature reaction field distribution produced by armature wingding current. Second, by using derived armature reaction field solution, the analytical solution for eddy current density distribution are also obtained. Finally, the analytical solution for eddy current loss induced in permanent magnets(PMs) are derived by using equivalent, electrical resistance calculated from PMs volume and eddy current density distribution solution. The analytical result from space harmonic method are validated extensively by comparing with finite element method(FEM).

무한히 긴 도체 스트립의 TM파 산란 특성 (Scattering Characteristics of The Infinite Strip Conductor for TM Waves)

  • 장재성;이상설
    • 한국통신학회논문지
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    • 제13권5호
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    • pp.437-443
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    • 1988
  • 무한히 긴 도체 스트립 위에 TM파가 입사될 때, 스트립의 전류 분포를 계산한다. 스트립의 경계조건식을 공간영역의 함수로 표시하면 convolution 적분을 포함하는 복잡한 식으로 나타난다. 그러나 그들을 주파수 영역으로 변환하면 전류 및도 함수와 Green함수의 곱으로 간단히 표시된다. 반복 계산 결과는 본 연구에서 제시한 반복 끝내기 조건을 만족할 때에 가장 좋은 결과를 보이고 있다. 반복과정의 수렴 속도를 Kastner의 방법을 이용하여 증가시켰다. 스트립에 유도되는 전류 분포는 스트립 폭에 따라 크게 변화하고 있음을 확인하였다.

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3차원 와전류 해석을 위한 등가자기회로방법의 개발 (Development of Equivalent Magnetic Circuit Network Method for 3 Dimentional Eddy current Analysis)

  • 허진;홍정표;현동석
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제51권5호
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    • pp.228-233
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    • 2002
  • A computational method for analysis of the 3 dimensional electro-magnetic induction problems has been developed. The developed method is capable of modeling the induced current and analyzing its characteristics using only scalar Potential at each node. A benchmark model of asymmetrical conductor with a hole is analyzed to verify the application of the developed method. The calculated value of magnetic flux density are compared with the measured value, and the results indicate that the developed method is valid. Also, Comparing with 3-D finite element method (FEM) results, we conformed effectiveness of the developed method for the accuracy and computation times.

무환히 긴 도체 스트립의 TE파 산란 특성 (Scattering Characteristics of the Infinite Strip Conductor for TE Waves)

  • 장재성;이상설
    • 대한전자공학회논문지
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    • 제26권5호
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    • pp.18-22
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    • 1989
  • 무한히 긴 도체 스트립 위에 TE파가 입사될때, 스트립에 유기되는 전류 분포를 계산한다. 스트립의 경계조건식을 공간 영역의 함수로 표시하면 convolution 적분을 포함하는 복잡한 식으로 나타난다. 그러나 그들의 주파수 영역으로 변환하면 전류밀도 함수와 Green함수의 곱으로 간단히 표시된다. 전류분포의 계산 결과는 본 연구에서 제시한 반복 끝내기 조건을 만족할 때 가장 좋은 결과를 보이고 있다.

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Submicron MOS 트랜지스터의 뜨거운 운반자에 의한 노쇠현상 (Hot-Carrier-Induced Degradation in Submicron MOS Transistors)

  • 최병진;강광남
    • 대한전자공학회논문지
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    • 제25권7호
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    • pp.780-790
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    • 1988
  • We have studied the hot-carrier-induced degradation caused by the high channel electric field due to the decrease of the gate length of MOSFET used in VLSI. Under DC stress, the condition in which maximum substrate current occures gave the worst degradation. Under AC dynamic stress, other conditions, the pulse shape and the falling rate, gave enormous effects on the degradation phenomena, especially at 77K. Threshold voltage, transconductance, channel conductance and gate current were measured and compared under various stress conditions. The threshold voltage was almost completely recovered by hot-injection stress as a reverse-stress. But, the transconductance was rapidly degraded under hot-hole injection and recovered by sequential hot-electron stress. The Si-SiO2 interface state density was analyzed by a charge pumping technique and the charge pumping current showed the same trend as the threshold voltage shift in degradation process.

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$Ar/CF_{4}$ 유도결합 플라즈마에서 식각된 $(Ba_{0.6}Sr_{0.4})TiO_{3}$ 박막의 손상 감소 (Study on Damage Reduction of $(Ba_{0.6}Sr_{0.4})TiO_{3}$ Thin Films in $Ar/CF_{4}$ Plasma)

  • 강필승;김경태;김동표;김창일;황진호;김태형
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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    • pp.171-174
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    • 2002
  • The barium strontium titannate (BST) thin films were etched in $CF_{4}/Ar$ inductively coupled plasma (ICP). The high etch rate obtained at a $CF_{4}(20%)/Ar(80%)$ and the etch rate in pure argon was twice higher than that in pure $CF_{4}$. This indicated that BST etching is sputter dominant process. It is impossible to avoid plasma-induced damages by the energetic particles in the plasma and the nonvolatile etch products. The plasma damages were evaluated in terms of leakage current density, residues on the etched sample, and the changes of roughness. After the BST thin films exposed in the plasma, the leakage current density and roughness increases. In addition, there are appeared a nonvolatile etch byproductsand from the result of X-ray photoelectron spectroscopy (XPS). After annealing at ${600^{\circ}C}$ for 10 min in $O_{2}$ ambient, the increased leakage current density, roughness and nonvolatile etch byproducts reduced. From the this results, the plasma induced damage recovered by annealing process owing to the relaxation of lattice mismatches by Ar ions and the desorption of metal fluorides in high temperature.

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Nanoprobing Charge Transport Properties of Strained and Indented Topological Insulator

  • Hwang, Jin Heui;Kwon, Sangku;Park, Joonbum;Lee, Jhinhwan;Kim, Jun Sung;Lyeo, Ho-Ki;Park, Jeong Young
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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    • pp.128.1-128.1
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    • 2013
  • We investigated the correlation between electrical transport and mechanical stress in $Bi_2Te_2Se$ by using a conductive probe atomic force microscopy in an ultra-high vacuum environment. Uniform distribution of measured friction and current were observed over a single quintuple layer terrace, which is an indication of the uniform chemical composition of the surface. By measuring the charge transport of $Bi_2Te_2Se$ surface as a function of the load applied by a tip to the sample, we found that the current density varies with applied load. The variation of current density was explained in light of the combined effect of the changes in the in-plane conductance and spin-orbit coupling that were theoretically predicted. We suppose that the local density of states is modified by tip-induced strain, but topological phase still remains. We exposed a clean topological insulator surface by tip-induced indentation. The surface conductance on the indented $Bi_2Te_2Se$ surface was studied, and the role of surface oxide on the surface conductance is discussed.

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Altered Delayed Rectifier $K^+$ Current of Rabbit Coronary Arterial Myocytes in Isoproterenol-Induced Hypertrophy

  • Kim, Na-Ri;Han, Jin;Kim, Eui-Yong
    • The Korean Journal of Physiology and Pharmacology
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    • 제5권1호
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    • pp.33-40
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    • 2001
  • The aim of present study was to define the cellular mechanisms underlying changes in delayed rectifier $K^+\;(K_{DR})$ channel function in isoproterenol-induced hypertrophy. It has been proposed that $K_{DR}$ channels play a role in regulation of vascular tone by limiting membrane depolarization in arterial smooth muscle cells. The alterations of the properties of coronary $K_{DR}$ channels have not been studied as a possible mechanism for impaired coronary reserve in cardiac hypertrophy. The present study was carried out to compare the properties of coronary $K_{DR}$ channels in normal and hypertrophied hearts. These channels were measured from rabbit coronary smooth muscle cells using a patch clamp technique. The main findings of the study are as follows: (1) the $K_{DR}$ current density was decreased without changes of the channel kinetics in isoproterenol-induced hypertrophy; (2) the sensitivity of coronary $K_{DR}$ channels to 4-AP was increased in isoproterenol-induced hypertrophy. From the above results, we suggest for the first time that the alteration of $K_{DR}$ channels may limit vasodilating responses to several stimuli and may be involved in impaired coronary reserve in isoproterenol-induced hypertrophy.

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인공 체액 조건에서 임플랜트용 티타늄 소재의 부식 특성 (Corrosion Behavior of Titanium for Implant in Simulated Body Fluids)

  • 이중배;최기열
    • 한국표면공학회지
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    • 제37권2호
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    • pp.110-118
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    • 2004
  • The corrosion of pure titanium (CP- Ti Grade 2) and titanium alloy (Ti6Al4V ELI) were studied under various conditions of simulated body fluids. The static immersion test and the electrochemical test were performed in accordance with ISO 10271 : 2001. For the electrochemical test, the open circuit potential was monitored as a function of time, and the cyclic polarization curve was recorded. The corrosion resistance was evaluated from the values of corrosion potential, passivation current density, breakdown potential, and the shape of hysteresis etc. The effects of alloy type, surface condition, temperature, oxygen, and constituents in the fluids such as acid, chloride were estimated. Both specimens had extremely low dissolution rate in the static immersion test. They showed strong passivation characteristics in the electrochemical test. They maintained negligible current density throughout the wide anodic potential range. The passive layer was not broken up to 2.0 V (vs. SCE). The hysteresis and the shift of passivation potential toward the anodic direction was observed during the reversed scan. The passivation process appeared to be accelerated by oxygen in air or that dissolved in the fluids. The passivation also proceeded without oxygen by the reaction of constituents in the fluids. Acid or chloride in the fluids, specially later weakened the passive layer, and then induced higher passivation current density and less shift of passivation potential in the reversed scan. CP-Ti Grade 2 was more reactive than Ti6Al4V ELI in the fluids containing acid or chloride, but thicker layer produced on its surface provided higher corrosion resistance.