• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.9
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• pp.898-906
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• 2002

In this paper, we investigated the improvement degree of transmission distance of the various initial frequency chirped optical pulse with 5 dBm initial power dependence on the various bit rate and fiber dispersion coefficient, when MSSI(Mid-Span Spectral Inversion) with the optimal pump power condition is adopted for the compensation method for optical pulse distortion. And we analyzed the influence of mutual relation of optical pulse frequency chirp and Kerr effect on the MSSI methods for the long-haul optical transmission through the computer simulation. We found that the compensation degree of distorted optical pulse varies as a consequence of the variation of combined phase modulation of self phase modulation(Kerr effect) and initial frequency chirp parameter dependence on the fiber dispersion coefficient. And we found that, if the transmission bit rate is increased k times, the dispersion coefficient value of dispersion shift fiber is decreased $2^k$ times so as to be almost the same performance of the transmission system with k times lower bit rate.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.729-731
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• 2013

The compensation characteristics of 40 Gbps optical signals depending on figure of merit (FOM) of dispersion compensating fiber with dispersion coefficient of -125 ps/nm/km are investigated in this research. Simulation results show that the more fiber span number and launch power increase, the more the effects of FOM of DCF on the compensated signals increase. However, it is also confirmed that the more the effects of optical nonlinearity increase, the more FOM decrease.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.1
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• pp.55-59
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• 2004

전파의 특성을 측정하기 위해서 사용되는 디지털 주파수 측정기는 안테나를 통해서 수신기에 입력된 고주파 신호의 주파수를 측정하는 장치로써, 전파 정보 수집 장비의 중요한 구성품 중 하나이다. 이 분야는 고주파 기술이 발달된 미국이나 유럽에서 대부분의 장비를 개발해 왔으나 금번에 설계 제작된 주파수 측정기는 온도보상 등을 고려하여 정밀하게 설계제작 함으로써 수신 감도 -70㏈m에서 펄스폭이 l00㎱ 이상인 펄스 신호와 지속파(CW)신호의 주파수를 정확하게 측정하였다.

• Journal of the Korean Magnetics Society
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• v.15 no.4
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• pp.250-255
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• 2005

A 8 MA/m-class pulsed field magnetometer has been constructed by composing a pulsed field magnet, a pickup coil, analog integrators, a digital storage oscilloscope and a personal computer. For precision measurements, a 3-axis compensation principle has been applied for the fabrication of pickup coil, and the compensation level of the order of $10^{-6}$ and the sensitivity of $5{\cdot}10^{-7}\;Am^2$ for magnetic moment have been obtained. The high sensitivity of the magnetometer is good enough for measurements of magnetic properties of rare earth magnets in small size or thin films shorter than $3\;mm{\phi}$ in diameter.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.72-73
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• 2014

본 논문에서는 ITER 펄스전원계통의 무효전력보상기(Reactive Power Compensator)의 해석 및 검증에 대하여 기술하였다. ITER 펄스전원계통은 66kV에 흐르는 무효전력량을 250MVar이하로 제한하기 위하여 정지형 무효전력보상기(Static Var Compensator)의 대표적인 장치인 싸이리스터 제어 리액터(TCR)와 고조파 필터(HF)로 구성된 무효전력보상기(RPC)를 사용한다. RPC에 적용되어 여러 ITER 초전도 코일 전원장치에서 발생하는 무효전력의 크기를 예측하여 보상하는 무효전력 보상기법을 해석한다. 본 논문에서는 RPC의 무효전력 보상동작을 실제 제어기와 RTDS를 연동하여 실험하여 검증하였고, RPC의 유무에 따라서 66kV 계통의 무효전력 최대값이 120MVar에서 40MVar로 감소하는 것을 확인하였다.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2497-2500
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• 2003

본 논문에서는 저속으로 회전하는 모터의 속도를 추정함에 있어서 속도 관측기를 이용하고 적절한 보상을 통해 가속/감속 운전 시에도 속도 추정 성능을 개선시킨다. 가속도 정보를 이용한 보상을 통해, 모터 인코더카운터 값으로부터 발생하는 양자화 오차를 줄인다. 가속/감속 운전시 인코더 펄스에 의한 평균속도는 펄스가 발생한 시점에서 불연속일 수밖에 없게 된다. 제안된 방식은 이 불연속적인 평균속도를 가속도 보상을 통해 연속적으로 증감하는 보상된 속도를 얻고 이를 다시 관측기 입력에 보상하여 양자화 오차를 감소시킨다.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.153-154
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• 2011

본 논문은 비대칭 2상 SRM의 센서리스 속도제어를 위한 초기각 검출 및 초기 기동방식과 자속관측기를 적용한 센서리스 제어에서 전동기의 온도 및 파라미터 변동에 의한 자속 오차 성분으로 인해 발생하는 위치 추정오차를 보상하기 위한 새로운 보상기를 제안한다. 제안된 방식은 전압펄스 인가로 초기각을 검출하고 검출된 초기 위치정보를 바탕으로 동일한 전압펄스 인가를 통해 비여자상이 여자상이 되는 회전자 위치를 검출하여 상여자를 교체하는 초기기동을 통해 자속관측기를 적용한 센서리스 제어로 안정적으로 진입하도록 한다. 이 때, 제안된 추정위치 보상기를 통해 추정된 센서리스 위치를 순시적으로 보상한다.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.583-587
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• 2003

In this paper, the optimal performance of optical second-order polarization mode dispersion (PMD) compensation has been investigated theoretically in terms of minimization of the root-mean-square (RMS) pulse broadening. The optimal compensation vector in feedforward-type second-order PMD compensation has been derived, and the RMS pulse broadening factor after the optimal second-order PMD compensation has been analytically calculated. The calculated result has been compared with the previously reported simulation result where numerically optimized feedback scheme was adopted. They are in good agreement, which verifies the validity of the derivation. The investigation in this work will form the basis for the implementation of the feed-forward-type second-order PMD compensation.

• Korean Journal of Optics and Photonics
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• v.12 no.1
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• pp.32-39
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• 2001

We analyze the effectiveness of the PMD compensation as a function of the link PDL, to acquire the guidelines for the successful deployment of PMDC. Result shows that the amount of BER improvement from the PMDC is decreased as the link PDL increases. Because PDL elements in the transmission system make well-defined two PSPs under the absence of PDL not orthogonal anymore, and proper definition of fast and slow polarization harder. Accordingly, consideration of PDL's potential effects must be needed for design of polarization mode dispersion compensation.sation.

• Investigative Magnetic Resonance Imaging
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• v.10 no.2
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• pp.70-80
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• 2006

Spin echo gradient moment nulling pulse sequences were designed and implemented on a clinical magnetic resonance imaging system. A new technique was introduced for flow compensation that minimized echo time and effectively suppresses unwanted echoes on the slice selection gradient axis in spin echo sequences. A unified gradient shape was used in all orders of flow compensation up to the third order. A dual-purpose gradient was applied for flow compensation and to reduce unwanted artifacts. The sequences were used to generate images of phantoms and/or human brains. This technique was especially good at reducing eddy currents and artifacts related to imperfection of the refocusing pulse. The developed sequences were found to have shorter echo times and better flow compensation in through-plane flow than those of the previous models that were used by other investigators.