• Journal of applied mathematics & informatics
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• 제32권3_4호
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• pp.323-330
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• 2014

The notion of transitive filters is introduced in lattice implication algebras. A necessary and sufficient condition is derived for every filter to become a transitive filter. Some sufficient conditions are also derived for a filter to become a transitive filter. The concept of absorbent filters is introduced and their properties are studied. A set of equivalent conditions is obtained for a filter to become an absorbent filter.

• Journal of Power Electronics
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• 제18권4호
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• pp.1165-1177
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• 2018

This paper investigates the active damping of grid-connected LCL filter resonance using high-pass filter (HPF) of the grid current. An expression for such HPF is derived in terms of the filter components. This expression facilitates a general study of the actively damped filter behavior in the discrete time domain. Limits for the HPF parameters are derived to avoid the excitation of unstable open loop poles since such excitation can reduce both the damping performance and the system robustness. Based on this study, straightforward co-design steps for the active damping loop along with the fundamental current regulator are proposed. A numerical example along with simulation and experimental results are presented to verify the theoretical analyses.

• 충청수학회지
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• 제32권1호
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• pp.53-67
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• 2019

The notions of closed elements and dense elements are introduced in BE-algebras. Characterization theorems of closed elements and closed filters are obtained. The notion of dense elements is introduced in BE-algebras. Dense BE-algebras are characterized with the help of maximal filters and congruences. The concept of D-filters is introduced in BE-algebras. A set of equivalent conditions is derived for every D-filter to become a closed filter.

• 한국전자파학회논문지
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• 제28권11호
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• pp.924-927
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• 2017

본 논문에서는 6~18 GHz 대역 8-비트 true time delay(TTD) 회로의 설계 및 측정결과에 대하여 기술하였다. 단위 지연 회로는 상대적으로 시간 지연 변화율이 일정한 m-유도 필터(m-derived filter)를 이용하였다. 설계한 8-비트 TTD는 2개의 single-pole double-throw(SPDT)와 7개의 double-pole double-throw(DPDT) 스위치로 구현하였으며, 인덕터를 이용하여 반사 특성을 개선하였다. 설계된 8-비트 TTD는 $0.18{\mu}m$ CMOS 공정을 이용하여 제작하였다. 측정된 TTD 회로의 시간 가변 범위는 250 ps이고, 시간 지연 해상도는 약 1 ps이다. 6~18 GHz의 동작 주파수에서 RMS 시간 지연 오차는 11 ps 미만이며, 입출력 반사 손실은 10 dB 이상이다. 공급 전압은 1.8 V이며, 소비 전력은 0.0 mW이다. 칩 면적은 $2.36{\times}1.04mm^2$이다.

• 전자공학회논문지D
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• 제34D권6호
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• pp.58-64
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• 1997

The wavelengt lockin gsystem of the optical fabry-perot filter theoretially derived and experimentally realized by using the ithering method in order to compensate the laser wavelength drift increasing the BER of the WDM system. The deviation between the laser wavelength and the optical filter center wavelength is compensated by applying a suitable voltage to the PZT. Accordingly, the laser wavelength selected by the fabry-perot filter always maintains the condition of maximum transmission powr. A wavelength locking system has been demonstrated using a fiber fabry-perot filter with a free spectral range of 80nm and an FWH of 1nm. The voltages of the sine wave generated for dithering was 20mV and 10mV, the frequency was 2kHz and center wavelength of the tunable laser was 1550nm. In this paper, the locking system have 20ms of locking time and 2nm of locking range.

• Journal of applied mathematics & informatics
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• 제35권5_6호
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• pp.513-528
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• 2017

The concept of weak implicative filters is introduced in BE-algebras. Some characterizations of weak implicative filters are derived in terms of filters of a BE-algebra. Fuzzification is applied to the class of weak implicative filters. Some properties of fuzzy weak implicative filters are studied with respect to fuzzy relations and homomorphisms. The notion of triangular normed fuzzy weak implicative filters is introduced in BE-algebras and their properties are studied.

• 천문학회보
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• 제42권1호
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• pp.58.1-58.1
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• 2017

National Youth Space Center has recently founded the Deokheung Optical Astronomy Observatory (DOAO) 1m Telescope, which accepts community observing applications since 2016. Standardization and calibration of the new observing facility are essential for astronomical research. In this poster, we present standardization processes and preliminary results for photometry of the Johnson-Cousins BVRI filter system. We selected sample data from a night in stable weather condition. After bias, dark, and flat corrections and photometry using ccdred and daophot package of IRAF, we derived standardized band pass parameters including color terms. The corrected photometry results of the BVRI filter system show reduced deviations from the standard magnitudes in the literature. In addition, we calculated atmospheric extinction coefficients and limiting magnitudes of the telescope system. We plan to extend these standardizing processes to flux calibration of narrow band filters, e.g. $H{\alpha}$ filter.

• 한국지리정보학회지
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• 제13권2호
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• pp.157-167
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• 2010

언센티드 칼만 필터 기반의 역방향 필터를 유도하고 시뮬레이션 테스트를 통하여 확장 칼만 필터, 언센티드 칼만 필터, 그리고 확장 칼만 스무더로부터의 위치결과와 비교 분석하였다. 시뮬레이션은 GPS의 수신환경이 극단적으로 좋지 않을 경우를 고려하여 $40m{\times}40m $ 의 공간에서 4개의 곡선 그리고 5개의 직선구간으로 이루어진 궤적에서 시작점과 끝점만을 기지점으로 가정하여 수행하였다. 실험 결과 스무더는 순방향 필터에 비하여 최대 위치 오차값이 약 8~9m 정도 크게 감소하는 결과를 보여주었다. 스무더의 경우 위치오차를 직선구간과 곡선구간으로 나누어 분석하였는데, 언센티드 칼만 스무더가 확장 칼만 스무더에 비하여 직선 구간에서는 최대 10cm, 곡선 구간에서는 최대 23cm 향상된 결과를 나타내었다.

• 한국통신학회논문지
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• 제22권6호
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• pp.1251-1258
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• 1997

Generally, it is very important to study selective coupling between cavities of the filter structure using multimode cavity resonator. In this paper, we have manufactured 5-pole bandpass filter(BPF) using dual and triple-mode cavity resonator. To do so, we have derived the formulas for coupling coefficient about coupling between TE-modes from TM/TE-mode's tangential and lognitudinal field intensities each other. To implement the Chebyshev response, the intercabity slot combining dual-mode and triple-mode is designed to couple one H-field of TE-mode parallel to slot plate. In this paper, specially it is derived the formulas for T $E_{11p}$-mode from TE-modes, and determined after obtaining location and size of intercabity slot from the equation. In this ppaer, based on this result, we designed and implmented teh bandpass filter operated at the center frequency of 14.5GHz with a Chebyshev response. For the manufactured cavity filter, dual-mode and triple-mode cavity are resonted by two orthogonal T $E_{113}$-modes, and by two orthogonal T $E_{113}$-modes and one T $M_{012}$-mode, respecitively. The 2-stage 5-pole BPF proposed in this paper has the insertion loss of -2.32dB, the reflection loss of -15dB in the passband, and the out-or-rejection of -67dB.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.299-303
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• 1993

In an underwater vehicle, the navigation error is mostly caused by the initial misalignment, the bias of a gyro and an accelerometer, and the sea current. Therefore, it is important that these error sources are estimated and compensated in order to reduce the navigation error. In this paper, the E.M.Log aided SDINS is designed by using the E.M.Log which measures the forward velocity of a vehicle. And the system error state equation and the measurement equation are derived and the suboptimal Kalman Filter is established for this aided SDINS. The simulation result showed that this had an important role in estimating and compensating these error sources, thus reducing the navigation error of an underwater vehicle.