• 한국통신학회논문지
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• 제16권10호
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• pp.972-980
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• 1991

LQG/LTR method have a theoretical constraint that it cannot applied to nonminimum phase plant. In this paper we suggest two methods of approximation of minimum phase plant for a given nonminimum phase plant to solve this constraint. Error is described by additive form which can reduce its magnitude in broad frequency range. A optimal approximation method was suggested by using Hankel operator theory and Nehan theory it is shown by example that the methods suggested can resolve the frequency domain constraint arised in Stein and Athans approximation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1836-1840
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• 2003

This paper, we propose a new phase-locked loop (PLL) system with the controllable output phase, independent from the output frequency, and lock-up time. This PLL system has a dual control loop is described, the inner loop greatly improved VCO characteristic such as faster speed response as well as higher operation bandwidth, to minimize the effect of the VCO noise and the power supply variation and also get better linearity of VCO output. The main loop is the heart of this PLL which greatly improved the output frequency instability due to the external high frequency noise coupling to the input reference frequency also the main loop can control the output phase, independent from the output frequency, and reduce the lock-up time of the step frequency response. The experimental results confirm the validity of the proposed strategy.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.146-149
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• 2003

To control the position, velocity and torque of the ultrasonic motor, a great variety of method are proposed such as the amplitude, phase difference, frequency and so on. In the case of phase difference method, it has some advantages: it can control the direction and velocity of rotation only adjusting the phase difference and it has wide control-band. During the USM driving on adjusting phase difference, its characteristic was transformed by the change of resonance-frequency of stator, which means that the resonance frequency is different according to the phase difference. Consequently, we need to set up the most suitable driving frequency according to each phase difference.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.97-99
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• 2003

커플링 수가 1개이고, 2.3GHz에서 사용할 수 있는 새로운 45$^{\circ}$ Schiffman 위상 천이기가 측정 결과와 함께 제시되었다. 제안한 테플론 기반 위상 천이기는 기존의 Schiffman 위상 천이기에 비해 더 작은 면적과 저 비용으로 제작할 수 있다. 이외에도 제작된 위상 천이기의 특성들이 추출되었고 또한 비교되었다. 제안한 위상 천이기는 특히 장래 2.3GHz 무선 응용에 유용할 것으로 보인다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1199-1201
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• 2005

In the synthetic aperture radar (SAR) system, the motion error is the main phase error sources and the motion compensation is very important. The phase gradient autofocus (PGA) is a state of art technique for phase error correction of SAR. It exploits the redundancy of the phase-error information among range bins by selecting the strongest scatter for each range bin and synthesizes them. The motivation of this paper is based on the observation that the redundancy of phase error is also among the cross-range direction. Moreover, the proposed method applies the weighting function to better utilize the phase error information. The validity of the proposed scheme for PGA is tested with some numerical simulation.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 춘계종합학술대회
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• pp.152-155
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• 2000

본 논문은 2 GHz대와 12 GHz대에서 동작하는 Phase Shifter를 제안한다. 이것을 위해 비유전율이 2.6인 마이크로 스트립 선로가 사용되었다. 2 GHz대에서 전송선로 위에 비유전율 9인 유전체를 덮어서 주파수 특성이 좋고 선형적인 phase 변화를 가지는 것을 보았다. 12 GHz대에서도 S21의 위상 변화가 유전체 소자의 위치를 변화시킴으로써 약 30。의 우수한 값을 얻을 수 있었다.

• 한국산업정보학회논문지
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• 제19권2호
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• pp.45-49
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• 2014

In this work, a phase shifter radio-frequency integrated chip (RFIC) using a simple all-pass network is presented. As a tuning element of the phase shifter RFIC, tunable capacitors with a multi-layer dielectric of a para-/ferro-/para-electrics using a high tunable BST ferroelectric and a low-loss BZN paraelectric thin film were utilized. In order to evaluate and analyze the fabricated phase shifter RFIC, the same elements such as an inductor and capacitor integrated into it are also fabricated and tested. The designed phase shifter RFIC was fabricated on a quartz substrate in the size of $1.16{\times}1.21mm^2$. As the test results, the maximum phase difference of $350^{\circ}$ is obtained at 15 V and its tuning frequency bandwidth is 90 MHz from 2.72 to 2.81GHz.

• 한국통신학회논문지
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• 제29권3A호
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• pp.311-317
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• 2004

Varactor 다이오드와 branch coupler를 이용한 반사형 아날로그 위상 변위기 설계에 대하여 기술하였다. 1단의 위상 변위기로 위상 변위를 크게 하기 위하여 마이크로 스트립 stub기법을 사용하였으며 2.260GHz 주파수대에서 제작 결과 170$^{\circ}$의 위상이 변화함을 확인하였다. 측정된 삽입손실을 3㏈ 이하이었고. 반사 손실은 12㏈ 이상이었다. 본 논문에서는 설계 기법과 제자 및 실험 결과를 상세히 기술하였다.

• Current Optics and Photonics
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• 제2권4호
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• pp.332-339
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• 2018

A new multi-frequency fringe projection method is proposed to reduce the nonlinear phase error in 3-D shape measurements using an adaptive compensation method. The phase error of the traditional fringe projection technique originates from various sources such as lens distortion, the nonlinear imaging system and a nonsinusoidal fringe pattern that can be very difficult to model. Inherent possibility of phase error appearing hinders one from accurate 3-D reconstruction. In this work, an adaptive compensation algorithm is introduced to reduce adaptively the phase error resulting from the fringe projection profilometry. Three different frequencies are used for generating the gratings of projector and conveyed to the four-step phase-shifting procedure to measure the objects of very discontinuous surfaces. The 3-D shape results show that this proposed technique succeeds in reconstructing the 3-D shape of any type of objects.

• 대한전자공학회논문지
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• 제26권8호
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• pp.1262-1269
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• 1989

For the efficient recognition of Korean characters, a modified ternary phase-only synthetic discriminanty function filter(MTPOF-SDF) is proposed. MTPOF-SDF can not only discriminate the true class patterns and the similar, symmetric, or patially included false ones but also recognize the diverse variations in true class patterns due to combinatorial form as the same ones. And scale and rotation-invariant recognition is achieved. To preserve the features of the characters, phase information should be used. And to contsrol phase information easily, ternary quantization of the phase is preferred. Also low resolution requirement is achieved for compatibility with low resulution devices such as spatial light modulators.