• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.317-319
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• 2003

This paper describes an adaptive distance relay for double-circuit line protection with mutual impedance and fault resistance. Double-circuit lines have two operating condition; both lines of a double-circuit line are in operation and one line is switched-off and both ends of the line are grounded. For optimal distance protection, the trip region is calculated, which have respect to mutual impedance and fault resistance.

• 한국통신학회논문지
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• 제26권12C호
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• pp.240-248
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• 2001

본 논문에서는 현재 우리 나라의 초고속 국가기간전송망의 기본 전송장비인 2.5Gb/s SDH 전송시스템에 적용되어 2-선 양방향 선로 스위칭 링의 자기치유동작을 가능하게 하는 공간분할스위치 소자의 설계와 시스템에의 적용을 다룬다. Compass tool로 설계된 스위치 소자는 1.25Gb/s의 스위치 처리용량을 가지며 0.8$\mu\textrm{m}$ CMOS gate-array로 제작되었다. 제안된 스위치 소자는 2-선 양방향 전송선로 상에 장애가 발생했을 때 신속한 자기치유동작을 가능하게 한다. 스위치의 구조는 Add/Drop 제어부, Cross-point switch, 데이터 프레임 위상 정렬부, 비장착(Unequipped) 신호 프레이머부, 프로세서 접속부 등으로 구성된다. 제작된 2개의 스위치를 병렬구조로 구성하여 2.5Gb/s SDH 전송시스템에 적용하여 시험한 결과 임의의 광선로 장애 시 신호채널들의 링 스위칭 동작으로 즉시 복구가 가능함을 보여준다.

• 전기전자학회논문지
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• 제14권3호
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• pp.232-235
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• 2010

기존의 수동 스위치를 사용한 스위치-라인 타입 위상변화기의 수동 스위치를 스위칭 증폭기로 대체한 60GHz CMOS 능동위상변화기를 소개하였다. 능동스위치 위상변화기는 능동스위치 블록과 수동 딜레이 네트워크 블록 구성되며, 기존의 vector-sum 위상변화기와 비교해 간단한 회로 구성이 가능하다. 능동스위치 블록은 On-Off state에 따라 다르게 요구되는 입출력 저항을 고려하여 설계하였고, 수동 딜레이 네트워크 블록은 회로의 크기를 최소화하기 위하여 일반적인 microstrip line 대신 lumped 인덕터와 커패시터를 사용하여 구성하였다. TSMC 65nm CMOS 공정을 이용하여 1-bit 위상변화기를 제작 및 측정하였으며, 그 결과 65GHz에서 평균 -4.0dB 의 삽입손실과 120도의 위상차를 얻었다.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2364-2375
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• 2018

Two-phase simultaneous excitation mode of the switched reluctance motor (SRM) has been shown to effectively improve the average torque output compared with traditional single-phase excitation mode. But the torque ripple of the two-phase excitation SRM with traditional winding distribution increases because of the inconsistent electromagnetic field. To reduce the torque ripple, a two-phase excitation 8/6 SRM with novel winding distribution is proposed in this paper. The static torques generated by various magnetic circuits are analyzed and obtained to verify the torque increase. Then the electromagnetic characteristics of the proposed SRM are investigated by the numerical calculation method in detail, including flux linkage, inductance, and torque. Finally, an experiment for measuring the SRM static electromagnetic characteristics and dynamic performance is designed and performed based on the novel mode, and the comparing results show that the proposed two-phase SRM is effective.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권1호
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• pp.70-82
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• 2014

A nano-power CMOS voltage reference is proposed in this paper. Through a combination of switched-capacitor technology with the body effect in MOSFETs, the output voltage is defined as the difference between two gate-source voltages using only a single PMOS transistor operated in the subthreshold region, which has low sensitivity to the temperature and supply voltage. A low output, which breaks the threshold restriction, is produced without any subdivision of the components, and flexible trimming capability can be achieved with a composite transistor, such that the chip area is saved. The chip is implemented in $0.18{\mu}m$ standard CMOS technology. Measurements show that the output voltage is approximately 123.3 mV, the temperature coefficient is $17.6ppm/^{\circ}C$, and the line sensitivity is 0.15 %/V. When the supply voltage is 1 V, the supply current is less than 90 nA at room temperature. The area occupation is approximately $0.03mm^2$.

• 전력전자학회논문지
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• 제12권1호
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• pp.98-106
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• 2007

본 논문에서는 개선된 온라인 턴 오프각 제어방식을 이용하여 스위치드 릴럭턴스 전동기의 성능최적화를 위한 온라인 전류제어방식을 제안한다. 성능최적화를 위한 제어방식은 에너지효율의 최대화와 토크리플 저감이라는 두가지 측면에서 접근하며, 두 가지 조건을 모두 만족할 수 있는 최적의 턴 오프 위치각은 제안된 알고리즘의 연산방식을 통해 획득된 턴 오프각 제어기를 통해 구현됨으로서 SRM의 성능최적화를 이룬다. 제안된 제어기는 토크와 전류 특성, 자속변동의 정보와 같은 복잡한 데이터베이스나 SRM이 가지는 고유의 자화곡선을 요구하지 않는다는 장점을 가지며 제안된 연산 제어기를 시뮬레이션과 실험을 통해 실제 적용가능성과 그 타당성을 입증한다.

• Journal of Communications and Networks
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• 제4권3호
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• pp.230-245
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• 2002

Usually the network-throughput maximization problem for constant-bit-rate (CBR) circuit-switched traffic is posed for a fixed offered load profile. Then choices of routes and of admission control policies are sought to achieve maximum throughput (usually under QoS constraints). However, similarly to the notion of channel “capacity,” it is also of interest to determine the “network capacity;” i.e., for a given network we would like to know the maximum throughput it can deliver (again subject to specified QoS constraints) if the appropriate traffic load is supplied. Thus, in addition to determining routes and admission controls, we would like to specify the vector of offered loads between each source/destination pair that “achieves capacity.” Since the combined problem of choosing all three parameters (i.e., offered load, admission control, and routing) is too complex to address, we consider here only the optimal determination of offered load for given routing and admission control policies. We provide an off-line algorithm, which is based on Lagrangian techniques that perform robustly in this rigorously formulated nonlinear optimization problem with nonlinear constraints. We demonstrate that significant improvement is obtained, as compared with simple uniform loading schemes, and that fairness mechanisms can be incorporated with little loss in overall throughput.

• 한국인쇄학회지
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• 제13권1호
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• pp.93-104
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• 1995

Liquid crystal-polymer composite(LCPC) films promising new materials for both projection displays and vision product. LCPC films consist of a continous liquid crystal phase embedded in a three- dimensional network of polymer matrix. The liquid crystal in these LC phases can be elecrtrically switched giving rise to an opaque scattering off-stats and a transparent, non-scatting on- stats. In this work. a premixture is composed of LC, UV-curable monomer and photonitiator. LCPC films are formed by photopolymerization induced phase separation from this premixture. In conclusion, structure and electro-optical properties of LCPC films strongly depends on the selection of monomer, LC content and curing rate.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.39-44
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• 2005

A broadband DC to 40 GHz 5-bit MMIC digital attenuator has been developed. The ultra broadband attenuator has been achieved by newly inserted the transmission lines in conventional Switched-T attenuator and the optimization of the transmission line parameters. Momentum was employed in design for an accurate performance prediction at high frequencies and Monte Carlo analysis was applied to verify performance stability against the MMIC process variation. The attenuator has been fabricated with 0.15 $\mu$m GaAs pHEMT process. This attenuator has 1 dB resolution and 23 dB dynamic range. High attenuation accuracy has been achieved over all attenuation range and full 40 GHz bandwidth with the reference state insertion loss of less than 6 dB at 20 GHz. The input and output return losses of the attenuator are better than 14 dB over all attenuation states and frequencies.

• Journal of Power Electronics
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• 제10권3호
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• pp.219-227
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• 2010

Telecom supplies need to conform to low Total Harmonic Distortion (THD) and high Power Factor (PF) as per IEC 61000-3-2 and IEEE 519-1992 standards. These high rating power supplies use a three phase utility in which low THD and high PF are realized via various passive and active wave shaping schemes. In this paper, a new design for three phase telecom power supplies is presented with circuit parameter values optimized for high performance in terms of a low THD, high PF, low ripple and high line and load regulation using a suitable combination of various strategies. The performance of the power supply is validated by extensive simulations.