• Korean Journal of Optics and Photonics
• /
• v.8 no.6
• /
• pp.450-455
• /
• 1997

A pulsed Ti:sapphire laser with a Z-folded cavity, which was pumped by a freqeuncy-doubled Nd:YAG laser, was developed. It shows 120 nm wavelength tuning range from 740 nm to 860 nm with 90 nm FWHM under a pumping energy of 3 mJ with 18% output coupler. Using a birefringent filter, the effective efficiency was improved about 10 times compare to without a birefringent filter. The output energy obtained was $\365mu$Jwith 4 nm FWHM. And the wavelength tuning range was broadened to about 160 nm within an output energy fluctuation of $\pm$10%.

• Korean Journal of Optics and Photonics
• /
• v.14 no.6
• /
• pp.674-679
• /
• 2003

We fabricated erbium-doped fiber ring laser with a new structure that can operate in C- & L-band wavelength region. The wave-length of the laser can be tuned continuously over 102 nm between 1510.4-1612.6 nm by insertion of the fiber Fabry-Perot tunable filter (FFP-TF) in the ring cavity. By use of the wavelength tunable characteristics of our fiber laser, we measured absorption spectra of more than fifty transition lines of the acetylene ($^{13}$ C$_2$H$_2$) molecule with high signal to noise ratio (SNR).

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.44 no.8
• /
• pp.16-21
• /
• 2007

CMOS variable gain amplifier (VGA) IC designs for the structure monitoring systems of the telemetries were developed. A three stage cascaded VGA using a differential amplifier and a linear-in-dB controller is presented. A proposed VGA is a modified version of a conventional VGA such that the gain is controlled in a linear-in-dB fashion through the current ratio. The proposed VGA circuit introduced in this paper has a dynamic range of 77 dB with 1.5 dB gain steps. It also achieved a gain error of less than 1.5 dB over 77 dB gain range. The VGA can operate up to 10MHz dissipating 13.8 mW from a single 1.8 V supply. The core area of the VGA fabricated in a Magnachip $0.18{\mu}m$ standard CMOS process was about $430{\mu}m{\times}350{\mu}m$. According to measurement results, we can verify that the proposed method is reasonable with regard to the enhancement of dynamic range and the better linear-in-dB characteristics.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.05a
• /
• pp.574-575
• /
• 2018

The generation of redundant data according to the spatial-temporal correlation in a wireless sensor network that reduces the network lifetime by consuming unnecessary energy. In this paper, data collection experiment through the particulate matter sensor is carried out to confirm the spatial-temporal data redundancy and we propose permitted limit setting method for data transmission to solve this problem. In the proposed method, the data transmission permitted limit is set by using the integrated average value in the cluster. The set permitted limit reduces the redundant data of the member node and it is shows that redundant data reduction is possible even in a variable environment of collected data by resetting the permitted limit in the cluster head.

• Proceedings of the KIEE Conference
• /
• 2003.10b
• /
• pp.224-226
• /
• 2003

권선형 유도 발전기는 고정자뿐만 아니라 회전자에도 전력을 공급할 수 있는 이중여자의 구조를 가지므로 제어의 폭이 넓은 장점을 가진다. 본 연구에서 구성하는 권선형 유도발전기 시스템은 계통 연계형으로 유도발전기의 고정자는 계통에 직접 연결되고, 회전자는 AC/DC/AC 컨버터를 통해 계통과 연결된다. 간 연구는 이러한 시스템에서 가변속의 동력아래 고정자측 유효전력과 무효전력을 회전자의 d-q 독립제어에 의하여 동시제어가 이루어지도록 하는 연구이다. 본 연구에서는 종래의 유도발전기 시스템에서 터빈의 속도가 동기속도 이상이 되어야만 일정한 전력을 얻을 수 있는 최대전력 점 트래킹 방식 보다 넓은 운전 범위인 동기속도 이하의 영역에서도 회전자 전력변환장치 용량이내에서 일정 전력제어가 가능하도록 하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2003.05a
• /
• pp.419-423
• /
• 2003

In this paper, we have constructed singly resonant KTP OPO system pumped by 532 nm to obtain broadly frequency tunable pulses. Also we have mathematically simulated frequency tuning range, phase matching angle for 900 nm output and threshold energy, and we calculated output intensity using wave propagation equations for optical parametric oscillator which include walk-off, pump depletion.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.6
• /
• pp.7-13
• /
• 2002

This paper introduced a new hybrid genetic algorithm, verified its performance, and applied it to the optimization of blade design and pitch control for 30kW pitch-controlled variable-speed horizontal-axis wind turbine system to determine the optimum blade chord and twist distributions that maximize the energy production for a given Weibull wind distribution and the optimum blade pitch angles that maintain constant power output.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2002.05a
• /
• pp.227-229
• /
• 2002

In this paper, we report on a microstrip line voltage controlled tunable bandpass filter. We used the characteristic the relative dielectric constant of thin film ferroelectrics depends on the applied dr voltage. we designed using Au/BSTO/MgO/Au structure. We cascaded many resonators for large furling range sustaining 1 GHz renter frequency, narrow band, low IL ($\leq$4 dB). We could design the BPF of which center frequency is 16 GHz, 1.9 GHz tuning range, the narrow bandwidth within 800 MHz, low insertion loss less than 3 dB by adjusting the gap of 3 cascaded resonators.

• Journal of Institute of Control, Robotics and Systems
• /
• v.3 no.6
• /
• pp.569-575
• /
• 1997

모델 불확실성이 있고 n축 자유도(degree of freedom)를 갖고 있는 로봇 동작부(manipulator)에 대해서 위치 정보만을 이용하여 가변 구조 제어기(variable structure controller)를 설계하였다. 모델의 불확실성이 존재하는 경우에도 제어기에 사용되는 속도를 잘예측하기 위해 고이득 관찰기를 사용 하였으며 고이득 관찰기를 사용할때 발생할 수 있는 상태변수의 피킹현상(peak phenomenon)를 적게 하게 하기위하여 제어기의 값을 제한 (globally bounded)하여 제어기를 설계하였다. 부하(payload)의 범위만 알고 있는 2축 자유도를 갖는 로봇 동작부에 대해서 제안된 제어 방법에 따라 제어기를 설계하여 그 성능를 확인 하였다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.7 no.8
• /
• pp.1751-1758
• /
• 2003

This paper describes speed control of a permanent split capacitor single phase induction motor using SHE PWM inverters. The inverter is controlled by V55 microprocessor and its range is larger than other systems. Due to the V/F control with SHE(Selected Harmonic Elimination) PWM, continuously variable speed is attained and THD(Total Harmonic Distortion) is decreased. This is verified by simulations and experimental results.