• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9C
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• pp.691-696
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• 2008

A new vocoder of Code Excited Linear Predictive (CELP) based on Adaptive Multi Rate (AMR) 7.4kbit/s mode is proposed in this paper. The proposed vocoder achieves a better compression rate in an environment of Speaker Dependent Coding System (SDSC) and is efficiently used for systems, such as OGM(Outgoing message) and TTS(Text To Speech), which needs only one person's speech. In order to enhance the compression rate of a coder, a new Line Spectral Pairs(LSP) code-book is employed by using Centroid Neural Network (CNN) algorithm. In comparison with original(traditional) AMR 7.4 Kbit/s coder, the new coder shows 27% higher compression rate while preserving synthesized speech quality in terms of Mean Opinion Score(MOS).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.1123-1131
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• 2005

In this paper, optimal position of optical phase conjugator (OPC) for best compensating distorted WDM channels due to both chromatic dispersion and self phase modulation (SPM) in $8{\times}40$ Gbps WDM systems is numerically investigated, and the eye opening penalty (EOP) and bit error rate (BER) characteristics of overall WDM channels at this position is investigated, comparing with that in case of OPC placed at mid-way of total transmission length. It is confirmed that the compensation extents in WDM system with OPC is more improved by the shifting OPC position from the mid-way of total transmission length, depending on the modulation format and fiber dispersion coefficient. Ant it is confirmed that, from a viewpoint of the reception performance, EOP of each channel is more or less different with one another, but the BER characteristics of overall channels are almost equal.

• Journal of Advanced Navigation Technology
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• v.7 no.1
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• pp.14-21
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• 2003

We investigated the optimum pump light power compensating distorted WDM signal due to both chromatic dispersion and self phase modulation (SPM). The considered system is $3{\times}40$ Gbps intensity modulation direct detection (IM/DD) WDM transmission system with path-averaged intensity approximation (PAIA) mid-span spectral inversion (MSSI) as compensation method. This system have highly nonlinear dispersion shifted fiber (HNL-DSF) as nonlinear medium of optical phase conjugator (OPC) in the mid-way of total transmission line. We confirmed that HNL-DSF is an useful nonlinear medium in OPC for wideband WDM transmission, and the excellent compensation is obtained when the pump light power of HNL-DSF OPC was selected to equalize the conjugated light power into the second half fiber section with the input WDM signal light power depending on total transmission length. By this approach, it is verified the possibility to realize a long-haul high capacities WDM system by using PAIA MSSI compensation method, which have HNL-DSF OPC with optimal pump light power depending on transmission length.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.35-36
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• 2013

본 논문은 EV(Electric Vehicle)에 사용되는 배터리의 충/방전 전류에 따른 SOC(State of Charge) 및 전압특성을 Matlab Simulink로 구현하였으며, 검증을 위해 양방향 DC-DC 컨버터를 설계하여 실험을 하였다. 배터리 모델에 사용된 파라미터는 Randles등가회로를 기반으로 펄스방전을 통해 추출하였고, 단자전압 계산부에 3D Look-up 테이블을 이용해 적용하였다. SOC계산부는 전류에 따른 용량변화를 보상하기 위해 Peukert Effect를 적용하였으며, FTP-75 전류패턴으로 온도($0^{\circ}C$, $25^{\circ}C$, $40^{\circ}C$)에 따라 실험한 결과 시뮬레이션의 오차율은 5%로 높은 정확도를 갖는 것을 확인을 통해 검증 하였다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.111-113
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• 2007

본 논문에서는 제논 유전체 장벽 방전형 평판형광램프용 Fly-Back방식 전자식 안정기를 설계하였다. 본 전자식 안정기는 Fly-Back방식의 능동형 역률 보상 회로와 인버터회로를 사용하여 기존의 Sine wave의 형태가 아닌 펄스파 형태의 출력을 만드는 고역률, 고신뢰성 전자식 안정기를 제작하였다. 제논 평판형광램프의 점등전압은 고압이 사용되므로 램프 파손의 경우와 무부하의 경우로부터 사고를 방지하기 위해 보호회로를 사용하여 이상전압, 이상전류에 의한 사고를 차단했다.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.4
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• pp.265-272
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• 2018

This paper proposes a new control method for the supercapacitor (SC) to compensate the pulsed load and to enhance the power quality of the DC microgrid. By coordinating the operating frequency, the SC is controlled to handle the surge current, while the low-frequency current component is dealt with by the remaining sources in the system. The operation mode of the SC unit is automatically changed based on the state of charge and DC bus voltage level. Meanwhile, the mismatch in the power demand is covered by the SC unit by regulating the DC bus voltage level. The effectiveness of the proposed method is verified experimentally by the prototype with two distributed generators and one SC unit.

• Korean Journal of Optics and Photonics
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• v.14 no.5
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• pp.515-520
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• 2003

Characteristics of an amplifier with repetition rate of a few KHz is investigated. The continuous flash lamp pumped Nd:YAG laser head is used as an amplifier. The thermally induced birefringence of the laser medium is compensated and the depolarization is reduced to 5% in a double-pass amplifier. The amplification factor of a four pass amplifier reaches to about 3.2 at the repetition rate 5-10 KHz and the pulse width is lengthened from 40 ns to 48 ns.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2006.05a
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• pp.75-78
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• 2006

본 논문에서 우리는 HIV-1 바이오 동역학모델의 퍼지 모델링 및 디지털 퍼지 제어 기법을 소개한다. 그것의 제어구조는 샘플링 점들에서 측정한 상태로부터 현재 상태를 대략적으로 예측하는 수치적 적분 구조를 사용한다. 제안된 지능형 디지털 재설계에서는 전역 상태-정합과 안정도 조건들을 동시적으로 만족하는 타당한 디지털 제어 이득들을 찾는 것이다. 우리는 보상된 블록-펄스 함수를 이용하여 새로운 전역 상태-정합 조건을 우선 제시하며 그리고 나서 안정도 조건들을 이 조건들에 추가한다. 유도된 조건들은 선형행렬 부등식으로 묘사되며, 그로인해 볼록 최적화 문제로 쉽게 해결될 수 있다. 또한, 안정도 조건으로 인한 성능 하강을 방지하기 위해 두 단계 지능형 디지털 재설계 과정이 제안된다. 첫 번째 단계에서는 전역 상태-정합만을 고려한 디지털 제어 이득을 찾는다. 두 번째 단계에서는 얻어진 디지털 제어하의 폐루프 시스템을 안정화 시키는 추가디지털 제어기를 설계한다.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.638-641
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• 2018

현재 선진국에서는 고출력 양성자 선형 가속기를 기반으로 한 의료용 암치료기인 BNCT(Boron Neutron Capture Therapy)에 대해 활발히 연구 중이며 다원시스도 2016년부터 A-BNCT 사업을 진행 중이다. A-BNCT에 적용된 양성자 선형 가속기의 RF(Radio Frequency)전원을 공급하기 위해 352 MHz, 1.5 MW의 고출력을 가지는 클라이스트론을 사용하였다. 클라이스트론의 출력인 RF의 크기와 위상을 안정적으로 제어하기 위해 90 kV, 30 A, 120 Hz, 1.7 ms의 구형파 출력을 가지는 고전압 전원장치를 적용하였다. 또한 고전압 전원장치의 출력전압 변동률을 0.5% 이내로 유지시키기 위해 전압보상회로를 적용하여 회로 시뮬레이션과 실부하 실험을 통해 펄스전원장치의 성능을 검증하였다.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.2
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• pp.233-240
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• 2019

High-altitude ElectroMagnetic Pulse(HEMP) is a high-power electromagnetic pulse caused by nuclear explosions at altitudes above 30 km. This pulse can cause serious damage to the electrical/electronic device. Therefore, there are a lot of studies on the effects of HEMP in the literature. When conducting studies on the effects of HEMP, it is essential to measure the simulated HEMP. Depending on the need for measurement, this paper focuses on the HEMP measurement method. This paper proposes a measurement method using frequency domain compensation to extract the correct waveform and solves the offset problem more efficiently than the conventional methods. The proposed method is verified by experiment using HEMP simulator and measurement system in ADD.