• 제목/요약/키워드: full-mode

검색결과 880건 처리시간 0.024초

OFDM 기반 다중 무선 통신 환경에서의 효과적인 모드 선택 기법 (An Efficient Mode Selection Method for OFDM Based Multi-System Wireless Communication Systems)

  • 박종민;강민수;조성호
    • 대한전자공학회논문지TC
    • /
    • 제45권2호
    • /
    • pp.19-25
    • /
    • 2008
  • 한정된 가용 주파수(usable frequency resource) 내에 여러 무선 통신 시스템들이 혼재(co-existence) 한 상황에서 시스템 간 절체(switching) 시 원치 않는 지연 시간이 발생 할 수 있다. 이러한 다중 무선 통신 환경 내에서 지연 시간을 감소시키는 시스템 선택 기법을 요구하고 있어 지연 시간을 최소화 하는 모드 선택 기법(MSM : mode selection method)을 제시 하였다. 효율적인 모드 선택 기법을 위해 각 표준별 프리엠블의 구조적 특성을 분석하여 모드 선택 시 전체 검색(full search) 보다 효율적인 부분 검색(partial search)을 이용하여 지연 시간을 최소화 하는 모드 선택 기법을 시뮬레이션 하였다. 부가 백색 가우시안 잡음(AWGN) 환경 내의 신호 대 잡음비(SNR)가 10dB, 비트 에러율(BER)이 $10^{-6}$ 이상 일 경우 효율적인 시스템 선택이 가능함을 매트랩을 이용하여 비교 검증 하였다.

Vector Passive Harmonic Mode-locking Fiber Laser Based on Topological Insulator Bi2Se3 Interacting with Fiber Taper

  • Li, Jian Ping
    • Journal of the Optical Society of Korea
    • /
    • 제20권1호
    • /
    • pp.135-139
    • /
    • 2016
  • I propose a vector passive harmonic mode-locked fiber laser based on topological insulator Bi2Se3 interacting with a fiber taper with a diameter of 7 μm. The particles of topological insulator are deposited uniformly onto the fiber taper with light pressure effect. By incorporating the fabricated saturable absorber into an Er-doped fiber laser cavity, stable mode-locked fiber is obtained. Due to the intense evanescent field of the fiber taper, strong confinement of light enhances the nonlinearity of the laser cavity, and passive harmonic mode-locking is performed. I observe a maximum harmonic mode-locking of 356th, corresponding to a frequency of 3.57 GHz. The pulse duration is 824 fs, and the full width at half maximum of the spectrum is about 8.2 nm. The polarization dependent loss of the saturable absorber is ~ 2.5 dB in the wavelength range of the C band. As the cavity contains no other polarization dependent device, the mode-locked laser is functioning in the vector state. The harmonic order vs pump power is investigated. To the best of our knowledge, this report is the highest frequency mode-locked fiber laser based on Bi2Se3. Experimental results indicate that the topological insulator Bi2Se3 functioning with a thin fiber taper is effective for vector harmonic mode-locking.

블로킹커패시터를 이용한 향상된 위상천이 펄스폭변조 풀브리지 컨버터 (Improved Phase-shift Pulse-width Modulation Full-bridge Converter using a Blocking Capacitor)

  • 정강률
    • 조명전기설비학회논문지
    • /
    • 제25권8호
    • /
    • pp.20-29
    • /
    • 2011
  • This paper presents an improved phase-shift pulse-width modulation (PWM) full-bridge converter using a blocking capacitor. As the proposed converter reduces the circulation energy by inserting only one series blocking capacitor at the primary side of the conventional phase-shift PWM full-bridge converter structure, it improves the operation characteristics of the conventional converter. In this paper, first, the operation of conventional phase-shift PWM full-bridge converter is roughly reviewed, and then the operational principle of the proposed converter is classified and explained by each mode. After that, a prototype design example based on the operational principle is shown. Then, the improved operation characteristics of the proposed converter are actually verified through the experimental results.

모드 전환형 펄스충전기론 이용한 폐납축전지 재활용에 관한 연구 (An Study for reuse of the waste lead battery using Pulse Charger with mode conversion type)

  • 신춘식;안영주;김상동;신영미;김종달;김동완
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 2007년도 학술대회 논문집 전문대학교육위원
    • /
    • pp.101-107
    • /
    • 2007
  • In this paper, the pulse charger with mode consersion type is proposed that can reuse the waste lead battery. The pulse charger uses the switch mode of the forward convert method. The pulse charger maintain the constant voltage in state removing the lead battery and when it connected the pulse charger, it is converted the charge mode of the constant current immediately. It continues the rapid charge until the full state of the lead battery. After that the pulse charger is converted to the charge mode of constant voltage automatically, and then it continues the normal charge. The experiment results show that the effectiveness of pulse charger such as the good performance and the prolonged durability in lead battery according to capacity states.

  • PDF

Effect of Subthreshold Slope on the Voltage Gain of Enhancement Mode Thin Film Transistors Fabricated Using Amorphous SiInZnO

  • Lee, Sang Yeol
    • Transactions on Electrical and Electronic Materials
    • /
    • 제18권5호
    • /
    • pp.250-252
    • /
    • 2017
  • High-performance full swing logic inverters were fabricated using amorphous 1 wt% Si doped indium-zinc-oxide (a-SIZO) thin films with different channel layer thicknesses. In the inverter configuration, the threshold voltage was adjusted by varying the thickness of the channel layer. The depletion mode (D-mode) device used a TFT with a channel layer thickness of 60 nm as it exhibited the most negative threshold voltage (-1.67 V). Inverters using enhancement mode (E-mode) devices were fabricated using TFTs with channel layer thicknesses of 20 or 40 nm with excellent subthreshold slope (S.S). Both the inverters exhibited high voltage gain values of 30.74 and 28.56, respectively at $V_{DD}=15V$. It was confirmed that the voltage gain can be improved by increasing the S.S value.

A High Birefringent Polymer Terahertz Waveguide: Suspended Elliptical Core Fiber

  • Wang, Jingli;Chen, Heming;Shi, Weihua
    • Journal of the Optical Society of Korea
    • /
    • 제18권5호
    • /
    • pp.453-458
    • /
    • 2014
  • A novel high birefringent polymer terahertz (THz) fiber with a suspended elliptical core is proposed in this paper. The introduction of an elliptical core can enhance asymmetry to realize high mode birefringence, and a large porous outer cladding effectively isolates the core-guided mode from interacting with the surrounding environment. A full-vector finite element method(FEM) is used to analyze the characteristics of the THz fiber. Simulation results show that the suspended elliptical fiber exhibits high mode birefringence on a level of $10^{-2}$ over a wide frequency range, and an extremely large mode birefringence(${\approx}0.06226$) is obtained when ellipticity is 0.2. Moreover, a suspended hollow elliptical core fiber is also discussed for the purpose of lower loss, however high mode birefringence and low relative absorption loss can not coexist in such a kind of fiber.

고속 스위칭에 의한 만능 전려변화기 구성 (Universal power converter using High-Speed Switching)

  • 이스난도;프라요가 부디;최우석;박성준
    • 전력전자학회:학술대회논문집
    • /
    • 전력전자학회 2013년도 전력전자학술대회 논문집
    • /
    • pp.337-338
    • /
    • 2013
  • Combination the several type of single phase power conversion utilized simply topology are proposed in this paper. Totally four kind of converter are investigated, they are Boost AC/AC Converter, Buck AC/AC Converter, Boost AC/DC Converter, and Buck DC/AC Converter. Two types action mode are presented to determine the functional of circuit. First is AC chopper action mode, representation of the AC/AC converter. AC chopper action mode offered the sinusoidal current waveform, better power factor, faster dynamics, and smaller input/output filter. They present high robustness, offer safe commutation and have high efficiency. The second is full bridge action mode, determined the transformation AC to DC power and otherwise. Four switching devices and one magnetic contactor will establish the mode operation of circuit and manage the flow of power proceed in proper. The correction and advance of the kind of converter are verified by simulation.

  • PDF

이산 적응슬라이딩 모드 제어를 이용항 전력계통 안정화 장치에 관한 연구 (A study on the power system stabilizer using discrete-time adaptive sliding mode control)

  • 박영문;김욱
    • 대한전기학회논문지
    • /
    • 제45권2호
    • /
    • pp.175-184
    • /
    • 1996
  • In this paper the newly developed discrete-time adaptive sliding mode control method is proposed and applied to the power system stabilization problem. In contrast to the conventional continuous-time sliding mode controller, the proposed method is developed in the discrete-time domain and based on the input/output measurements instead of the continuous-time and the full-states feedback, respectively. Because the proposed control method has the adaptivity property in addition to the natural robustness property of the sliding mode control, it is possible to design the power system stabilizer which can overcome both the minor variations of the parameters of the power system and the diverse operating conditions and faults of the power system. Mathematical proof and the various computer simulations are done to verify the performance and stability of the proposed method.

  • PDF

Triple-Mode Characteristics of Cylindrical Cavity Loading a Cylindrical Dielectric Resonator

  • Lee, Seung-Mo;Kim, Cha-Man;Park, Jong-Chul;Kim, In-Ryeol;Oh, Soon-Soo
    • 한국정보전자통신기술학회논문지
    • /
    • 제9권6호
    • /
    • pp.630-636
    • /
    • 2016
  • In this paper, a novel triple-mode cavity structure, designed for compactness and operating at 850 MHz, is analyzed. A cylindrical dielectric resonator is loaded into a metallic cylindrical cavity. Previous study has been focused on the analysis of the cylindrical dielectric resonator, but in this paper, the effect of the cylindrical metallic cavity has been analyzed. Enclosing the dielectric resonator inside the metallic cavity increases the resonant frequency of the dielectric resonator; however, this increases the quality factor and introduces the possibility of installing coupling screws. The principle of generation of triple-mode was investigated by parametric analysis. The generated triple-mode is TE011 mode and two orthogonally generated HEM121 modes. By adjusting the radius of the dielectric resonator, the height of the dielectric resonator, or the radius of the cylindrical metallic cavity, three modes could be coincided. However, the height of the metallic cavity keeps three modes separated. The mode characteristics of the proposed cavity are analyzed using a full-wave electromagnetic (EM) simulation. The proposed triple-mode cavity could be developed to triple-mode filter using a coupling screw, and the commercial application for the miniaturized filter below 1 GHz could be expected.

슬라이딩 모드 제어기법을 이용한 유도 전동기의 완전 디지털 제어기 설계 (A Design of Full-Digitalized IM Controller Using Sliding Mode Control Algorithm)

  • 강문호;김남정;유지윤;박귀태
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 1994년도 하계학술대회 논문집 A
    • /
    • pp.360-362
    • /
    • 1994
  • This paper presents a design and implementation of DSP-based full-digitalized sliding mode controller(SMC) for an induction motor(IM) fed by voltage source inverter(VSI) with intelligent power module(IPM). By using SMC with load torque observer, we can obtain improved control performances, i.e., robustness, high precision and low chattering. Furthermore, this paper emploies space vector modulation (SVM) method which is implemented to minimize hard ware configuration and to obtain modulation flexibility along with only DSP software operation.

  • PDF