• 대한수학회논문집
• /
• 제34권1호
• /
• pp.333-349
• /
• 2019

The paper study the curvature theory of a line-trajectory of constant Disteli-axis, according to the invariants of the axodes of moving body in spatial motion. A necessary and sufficient condition for a line-trajectory to be a constant Disteli-axis is derived. From which new proofs of the Disteli's formulae and concise explicit expressions of the inflection line congruence are directly obtained. The obtained explicit equations degenerate into a quadratic form, which can easily give a clear insight into the geometric properties of a line-trajectory of constant Disteli-axis with the theory of line congruence. The degenerated cases of the Burmester lines are discussed according to dual points having specific trajectories.

• 대한전자공학회논문지
• /
• 제13권6호
• /
• pp.12-15
• /
• 1976

본논문은 현재 AF주파수변역에서 90° 정위상기를 실현하고 있는 방법과는 전혀 다른 착상으로 VHF 고파수대에서 90° 정위상기를 실현하는 새로운 방법을 제시하였다. 이 90° 정위상기의 구조는 간단하며 분포정수소자인 전송선과 집중정수소자인 R.L.C로 용이하게 실현된다. This paper presents the realization method of 90° constant phase shifter in the VHF band, constructed by the entirely differens idea from the conventional method of the realization of constant phase shifter in the audio frequency range. The construction of 90° constant phase shifter is. simple and can be easily realized by using the distributed constant element, transmission line, and the lumped constant elements, R,C,L.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 C
• /
• pp.1186-1188
• /
• 1999

When we perform the test related to the power distribution system such as artificial fault test, protective coordination test, distribution automation test in short length test line, Lumped Constant Circuit, a kind of variable impedance, should be attached to the test line in order to make it equivalent to a real line in length electrically. In this paper we designed the positive sequence and zero sequence Lumped Constant Circuit with optimized inductor and resister for the modification of long, 16km, distribution line, when they are attached to the short, 4km, distribution test line.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 C
• /
• pp.1167-1169
• /
• 1999

This paper presents the new unified power flow controller(UPFC) load flow algorithm using UPFC transmission line constant model. The UPFC transmission line constant model represents a function of transmission line constant(G.B) UPFC's effect in power system. It can easily be incorporated in a load flow program. The algorithm is suited for monitoring the power system state as well as determining the magnitude and Phase angle of UPFC serial voltage source.

• 한국정보통신학회논문지
• /
• 제15권1호
• /
• pp.9-15
• /
• 2011

마이크로스트립 선로를 이용하여 기판의 유전율을 광대역에서 빠르고 쉽게 측정하는 방법을 제시하였다. 산란계수를 이용하여 1차 반사계수와 1차 전송계수를 구하여 기판의 복소 유전율과 복소 투자율을 계산하는 과정을 보였다. 기존에 유전율을 알고 있는 기판에 제작한 마이크로스트립 라인의 산란계수를 회로망분석기를 이용하여 측정하여 기판유전율을 확인하였다. 이 방법은 유전율을 모르는 기판의 유전율을 측정하는데 적용가능하다.

• Journal of Power Electronics
• /
• 제14권5호
• /
• pp.1000-1007
• /
• 2014

This paper proposes an on-line rotor time constant estimation strategy for indirect field oriented induction machines. The performance of the indirect field oriented control is dependent especially on the rotor time constant whose value varies according to the temperature. The proposed method calculates the difference between the nominal rotor time constant and the real value from the d- and q-axis integration terms of a proportional integral (PI) current regulator and the demanded voltages of the induction machine to regulate the current in the steady state. Because the proposed strategy has a simple structure and is available in wide speed and torque ranges, the proposed method can be easily used in the industrial field. The effectiveness of proposed strategy is verified with simulations and a 7.5kW experimental setup.

• 대한전자공학회논문지
• /
• 제19권3호
• /
• pp.13-18
• /
• 1982

본 논문은 마이크로스트립 선로의 실효 유전률에 관한 실험적인 연구이다. 자유 공간 파장대 관내 파장비의 2승으로 주어지는 실효 유전률을 테프론 유전체판으로 만든 공진기의 공진 현상을 이용하여서 측정하고 이것과 마이로스트립 선로상의 전류 분포를 Fourier 변환하여서 얻은 이론 계산치와를 비교 고찰하여 제작된 원형및 타원형 공진기로 부터 얻어진 실험치와 이론치가 8∼12GHz범위의 X-Band에서 # =1일때 거의 일치하는 결과를 얻을 수 있었다.

• 전기학회논문지
• /
• 제58권10호
• /
• pp.1995-1999
• /
• 2009

A partial discharge(PD) measurement is a very effective method to assess the insulation condition of high-voltage machines. It is necessary that the life time of the on-line PD measurement sensor is assessed. Therefore, the electrical life time assessment method of ceramic element was reviewed in order to estimate the life time of the on-line PD measurement sensor. The samples were prepared according to the reviewed method and were tested at 8kV, 9kV and 10kV. Based on the obtained results, the life time constant is shown above 59. Also, it is assumed that the estimated life time constant can be used to anticipate the life time and to assess the conformity of the on-line PD measurement sensor.

• 한국군사과학기술학회지
• /
• 제4권2호
• /
• pp.122-129
• /
• 2001

A characterization procedure for analyzing symmetric coupled MIS(Metal-Insulator-Semiconductor) transmission line is used the same procedure as a general single layer symmetric coupled line with perfect dielectric substrate from the extraction of the characteristic impedance and propagation constant for even- and odd-mode. In this paper, an analysis for a new substrate shielding symmetric coupled MIS structure consisting of grounded crossbar at the interface between Si and SiO2 layer using the Finite- Difference Time-Domain(FDTD) method is presented. In order to reduce the substrate effects on the transmission line characteristics, a shielding structure consisting of grounded crossbar lines over time-domain signal has been examined. Symmetric coupled MIS transmission line parameters for even- and odd-mode are investigated as the functions of frequency, and the extracted distributed frequency- dependent transmission line parameters and corresponding equivalent circuit parameters as well as quality factor for the new MIS crossbar embedded structure are also presented. It is shown that the quality factor of the symmetric coupled transmission line can be improved without significant change in the characteristic impedance and effective dielectric constant.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
• /
• pp.195-198
• /
• 1997

This paper proposes the effective compensation method of the rotor time constant of induction motor. An indirect vector control method is highly dependent on the motor parameters. To solve the problem of performance degradation due to parameter variation in an indirect vector control of induction motor, we compensate the rotor time constant by current error feedback. The proposed method is a simple on-line rotor time constant compensation method using the information from terminal voltages and currents. As the current error, difference between current command and estimated current, approaches to zero, the value of rotor time constant in an indirect vector controller follows the real value of induction motor. This scheme is valid transient region as well as steady state region regardless of low or high speed. This method is verified by computer simulation. For this, we constructed the simulation model of induction motor, indirect vector controller and current regulated PWM (CRPWM) voltage source inverter (VSI) using SIMULINK in MATLAB.