Introduction to Electrical Engineering (Principles i and Applications of Electrical l Engineering) i Dong-Weon Lee at MNTL School of Mechanical Systems Engineering g Chonnam National University
What is Engineering Purposeful use of Science What is lecture about Design of a turbine requires collaboration from engineers from many fields Gainful employment of Ohm s law, Kirchhoff s law, Maxwell s equation From electrons to networks and op-amps
Abstraction: 추상
Abstraction: 추상
Apply Maxell s equation: 전기장과자기장과의관계를기술하는 4 개의 Equations 1. 체적내부에전하가있을때체적의표면을관통하는전기력선의합은체적내부의전하량과같다 2. 닫힌체적의표면을관통하는자기력선의합은항상 0이다. 3. 변화하는전기력 (electric) 이발생하면항상그에수직하는자기력 (magnetic) 이발생하고 4. 그역도성립한다
Electrical engineering systems in the automobile 기계공학에서자동차는?
Basic in Electric Engineering (Cont.) 강원도무릉계곡.. Voltage( 電壓 )vs Current( 電流 )
Basic in Electric Engineering (Cont.) Car Heater Fan Speed-Control Application: Control? V 폭포? 12 V? V 차의풍량조절을위해손잡이를돌리면저항값이변화 전동기의전류가바뀌면서풍량이바뀜 이런저항회로를해석하기위하여 KCL, KVL 등의회로이론을도입 모터의저항은?
Basic in Electric Engineering (Cont.) Applications 전기의응용 - 전기밥솥 (electric rice cooker) - 전기프라이팬 - 토우스터 - 전기생선구이 - 전기오븐 - 전자레인지 (??????? oven ) - 전기포트 - 믹서 - 식기세척기 - 냉장고 -펌프 - 환풍기 - 에어컨 - 세탁기 - 청소기 Electric or Electrical 전자사전, 전자수첩, 전자계산기, 전자도서관 Microelectronics i
Basic in Electric Engineering (Cont.) Units 단위계 기본단위 : 길이 [meter : m] 질량 [kilogram : kg] 시간 [second : s] 온도 [kelvin : K] 전류 [ampere : A] 보조단위 : 각도 [radian : rad] 기계적단위계면적 [m 2 ] 체적 [m 3 ] 속도 [m/s] 가속도 [m/s 2 ] 각속도 [rad/s] 각가속도 [rad/s 2 ] 에너지 ( 일 ) [Joule : J = N. m] 에너지밀도 [J/m 3 ] Power [watt : W = J/s] 힘 [newton : N = kg. m/s 2 ] 압력, 응력 [Pascal : Pa = N/m 2 ] 모멘트 [N. m] 점도 [Pa. s] 질량밀도 [kg/m 3 ] 전기적단위계전하량 [coulomb : C = A. s] 커패시턴스 [farad : F = C/V] 전압 [volt : V = W/A] 전기저항 [ohm : Ω = V/A] 전기전도도 [siemens : S = A/V] 주파수 [hertz : Hz = 1/s] 자속 [weber : Wb = V. s] 자속밀도 [tesla : T = Wb/m 2 ] 인덕턴스 [henry : H = Wb/A]
Standard Prefixes
Basic in Electrical Engineering (Cont.) Electrical engineering = Electrical Eng. + Electronics Electronics is the study of the flow of charge through various materials and devices such as, semiconductors, resistors, it inductors, capacitors, nanostructures, and vacuum tubes. All applications of electronics involve the transmission of power and possibly information. Although considered to be a theoretical branch of physics, the design and construction of electronic circuits to solve practical problems is an essential technique in the fields of electronics engineering and computer engineering.
Basic in Electrical Engineering (Cont.) 전기의근원은전자 Hole 과 Electron 의차이는? 원자와전자의크기는? 마찰로전기가일어나는이유는? 자유전자의이동은왜발생하는지? 전자의이동과전류의관계는? 전하란? 시간에따라변화하는가?
Basic in Electrical Engineering (Cont.) 전기전자공학개론 사용하는용어 (Terminology), 각 element 의역할에관하여이해 RLC 의기본개념이해 & 반도체소자의이해 신호의필터링 & 증폭 수학적인기법을이용 회로내의임의의위치에서의전류및전압을계산 Power sources 건전지, 전압 / 전류기, 신호발생기등
Basic in Electrical Engineering (Cont.) Charges: ( 약 2500 년 Amber로부터처음발견 ) Charge 의중요특성 (1) positive (hole), negative (electron) 극성을가짐 (2) 전자전하의정수배 : 1791 년정전기에관한논문발표 (-1.6 10-19 C, 전하량을세는기준이되는전자의전하량 ) (3) 전기적효과를발생 - 전하가분리되면전압이발생, 전하가흐르면전류발생. - 전하양은전자전하양의정수배로불연속하지만워낙작은양 (-1.6 10-19 C) 이굉장히많으므로 ( 예 : 20 C 구리의경우전자밀도 10 23 개 /cm 3 ) 연속적이라고판단
Basic in Electrical Engineering (Cont.) Electrons: 전자 (fh (cf. Holes &P Proton) The electron is a fundamental subatomic particle that carries a negative electric charge. It is a spin-½ lepton that participates in electromagnetic interactions, and its mass is less than one thousandth of that of the smallest atom. Its electric charge is defined by convention to be negative, with a value of 1 in atomic units. Together with atomic nuclei, electrons make up atoms; their interaction with adjacent nuclei is the main cause of chemical bonding. Electrons have an electric charge of 1.6022 10 19 coulomb, a mass of 9.11 10 31 kg based on charge/mass measurements. The mass of the electron is approximately 1 / 1836 of the mass of the proton. The common electron symbol is e.
Basic in Electrical Engineering (Cont.) 정전기 동전기 (galvanic electricity): 도체내의전하운동 금속에서는전기발생시도체를타고흐르기때문에정전기현상이거의일어나지않음 정전기 (static electricity): 부도체의마찰시발생하는마찰전기 명주, 유리봉, 모피, 플라스틱등의절연물질에의해쉽게대전 전자를잃은물질은양전하로대전되고, 전자를얻은물질은음전하로대전 정전유도 : 양전하또는음전하로대전된물체에도체를가까이하면반대극성의전하가유도됨. 이에따라정전흡인력이발생 쿨롱의법칙 : 정전흡인력의정량화된계수 두전하사이의전기력은전기력선으로표시 양전하에서나와음전하로향함 분포밀도에의해전장의세기표시
Basic in Electrical Engineering (Cont.) 전류와전압 (Current and Voltage) Current: 정의 : 임의의단면을단위시간당전하의알짜흐름단위 : C/s = A (amperes) 1 A는 1 초에 1 coulomb의전하가흐른다는의미 Voltage: 정의 : 전하를분리시키는데드는단위전하당에너지단위 : J/C = V (volts) 1 V 는 1 Joule 의에너지로 1 coulomb 의전하를분리시켰다는의미
Basic in Electrical Engineering (Cont.) Example 2.1: 원통형도체의총전하량과흐르는전류는? 1 m 2r = 2 10-3 m Charge density(n) = 10 29 carriers/m 3 2r 전하량 (q) = 1.69 10-19 C Drift velocity(υ) =199 10 19.9 10-6 m/s Total charge & current (C/s)? Vol (V)= 3.14 10-6 m 3 # of carriers (N) = V n = 3.14 10 23 carriers Total charges = qn = (1.69 10-19 C) (3.14 10 23 )=53 10 3 C 단위길이당 Charge density(q) 는? 53 10 3 C/m Current(A) : Q υ = (53 10 3 )C/m (19.9 10-6 )m/s I = ~1 A(C/s)
Basic in Electrical Engineering (Cont.) Power & Energy 1W=1J/s1J/
Basic in Electrical Engineering (Cont.) Ex) 기초개념 : 1l 의물을데우는데필요한전력은? 가정 : 전열기의소비전력 500W, 물의온도는 20ºC, 끓는온도 100ºC (1 cm 3 의물을 1 도올리는데필요한열량 1Cal) A) 결국 1000 ml (100ºC-20ºC) = 80,000[Cal] 의열이필요 전력량 [Ws] = 열량 [Joule] Cal = 0.24 I 2 R t ~ 333333 [Ws] 의전력량필요 1 ml = 1 cm 3 1 Cal = 4.18605 J 1 W = 1 J/s 1 초에 500 [Ws] 이므로약 666 초의시간이필요 ; 1l 의물을끓이기위해서는약 11 분 6 초의시간이필요 1500 ~ 2000 W
이미지를표시할수없습니다. 컴퓨터메모리가부족하여이미지를열수없거나이미지가손상되었습니다. 컴퓨터를다시시작한후파일을다시여십시오. 여전히빨간색 x 가나타나면이미지를삭제한다음다시삽입해야합니다. Principles and Applications of Electrical Engineering Basic in Electrical Engineering (Cont.) Review Electrical Engineering & Electronics Electrical Circuit : Energy or signal/information processor Circuit element : 회로를구성하는전기적인소자 저항, 커패시터, 인덕터, OP-AMP 등 전기공학에서는모든현상을회로로표현하며, 이런현상을수학적으로표현하는것을모델링이라정의
Basic in Electrical Engineering (Cont.) Review: 표현방법 RMS 값?