• ETRI Journal
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• 제46권3호
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• pp.421-431
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• 2024

In this study, a direct position tracking method for non-circular (NC) signals using distributed passive arrays is proposed. First, we calculate the initial positions of sources using a direct position determination (DPD) approach; next, we transform the tracking into a compensation problem. The offsets of the adjacent time positions are calculated using a first-order Taylor expansion. The fusion calculation of the noise subspace is performed according to the NC characteristics. Because the proposed method uses the signal information from the previous iteration, it can realize automatic data associations. Compared with traditional DPD and two-step localization methods, our novel process has lower computational complexity and provides higher accuracy. Moreover, its performance is better than that of the traditional tracking methods. Numerous simulation results support the superiority of our proposed method.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2005년도 추계학술대회 논문집
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• pp.196-198
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• 2005

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.71.3-71
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• 2001

Passive Stabilization method and active stabilization method are mainly used to comprise a control system of platform stabilizer. Passive Stabilization method has demerits because of size and weight except that control structure is simple while active stabilization method using sensors can reduce size and weight, it requires high sensor technique and control algorithm. In this paper, a stabilizing controller using adaptive fuzzy control technique and floating-point processor(DSP) is suggested.

• 한국지반공학회지:지반
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• 제12권6호
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• pp.21-36
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• 1996

흙과 Geogrid사이의 응력 전달은 마찰저항 및 수동저항으로 나눌 수 있는데 Geogrid의 횡방향 요소에 작용하는 수동저항은 그 메카니즘이 복잡하여 아직까지 거동이 명확하게 파악되지 못하고 있다. 이러한 수동저항의 메카니즘을 이해하기 위하여 돌기가 있는 보강재에 대한 직접 전단시험을 유한 요소 방법으로 해석하였다. 유한 요소해석으로 돌기의 간격에 따라 수동저항의 크기, 파괴형태, 응력 및 변형 분포 등을 분석하였으며 일 결과들을 실제 계측치와 비교 분석하여 Geogrid의 횡방향 요소에 작용하는 보강재의 수동저항의 거동을 파악하도록 하였다. 또한 흙의 종류에 따라 수동저항의 메카니즘을 파악하기 위해 점성토에 작용하는 수동저항의 거동을 예측하였다.

• Journal of Power Electronics
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• 제13권2호
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• pp.206-213
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• 2013

In this paper, an improved passive snubber is investigated in a single-phase single-stage full-bridge boost power factor correction (PFC) converter, by which the voltage spike across primary side of the power transformer can be suppressed and the absorbed energy can be transferred to the output side. When compared with the basic passive snubber, the two single-inductors are replaced by a coupled-inductor in the improved snubber. As a result, synchronous resonances in the snubber can be achieved, which can avoid the unbalance of the voltage and current in the snubber. The operational principle of the improved passive snubber is analyzed in detail based on a single-phase PFC converter, and the design considerations of both the snubber and the coupled-inductor are given. Finally, a laboratory-made prototype is built, and the experimental results verify the feasibility of the proposed method and the validity of the theoretical analysis and design method.

• 한국음향학회지
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• 제23권2호
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• pp.109-116
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• 2004

본 논문에서는 수중 환경에 Y자형으로 배치된 3조의 수동 선배열 소나 (Passive linear may sonars) 센서의 정보 연관 기법에 대해서 다룬다. 3조의 PLAS의 정보 연관은 NP-Hard로 알려진 3차원 할당 문제로 변형된다. 일반적인 수동 센서의 경우 기존의 접근 방법을 이용할수 있지만 방위 정보에 자우 불확실성 (Bearing ambiguity)이 존재하는PLAS에서는 개선된 방법이 필요하다. 특히 본 논문에서는 주파수 정보를 통한 가중치를 이용하여 방위 오차에 강인한 정보 연관 기법을 제안하였으며 PLAS와 표적간의 기하학적인 관계에 따른 ghost 문제 발생 영역을 분석하였다. 다중 표적 환경에서의 모의 실험을 통해 개선된 방법의 정보 연관 성능에 대해 알아보았다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.196-199
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• 2001

This paper deals with current harmonics and unbalanced source voltages compensation using combined filter system. Filter system consists of a series active filter and parallel passive filters. Passive filters were a traditional method to compensate current harmonics, so those were installed in power system widely. The active filter can be a substitution to improve filtering characteristics and complement drawbacks of the passive filter. The combined system of the active power filter and passive filter can has a better compensation performances and economical goods. The series type active power filter injects compensation voltage into power system by transformers. It's compensation principle is able to applicate for voltage compensation. A new control algorithm for series active filter to compensate current harmonics and unbalanced source voltages is proposed. In the proposed algorithm, a compensation voltage for harmonic reduction is calculated directly by instantaneous reactive power theory, and a compensation voltage for unbalanced source voltage is calculated in based on a synchronous reference frame. By experiments, we show validity of proposed compensation method.

• Current Optics and Photonics
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• 제7권1호
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• pp.47-53
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• 2023

We propose a centralized passive-optical-network monitoring scheme using the resonance-spectrum properties of a Fabry-Perot cavity based on fiber Bragg gratings. Each cavity consists of two identical uniform fiber Bragg gratings and a varying cavity length or grating length, which can produce a unique single-mode resonance spectrum for the drop-fiber link. The output spectral properties of each cavity can be easily adjusted by the cavity length or the grating length. The resonance spectrum for each cavity is calculated by the transfer-matrix method. To obtain the peak wavelength of the resonance spectrum more accurately, the effective cavity length is introduced. Each drop fiber with a specific resonance spectrum distinguishes between the peak wavelength or linewidth. We also investigate parameters such as reflectivity and bandwidth, which determine the basic performance of the fiber Bragg grating used, and thus the output-spectrum properties of the Fabry-Perot cavity. The feasibility of the proposed scheme is verified using the Optisystem software for a simplified 1 × 8 passive optical network. The proposed scheme provides a simple, effective solution for passive-optical-network monitoring, especially for a high-density network with small end-user distance difference.

• 조명전기설비학회논문지
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• 제27권11호
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• pp.27-36
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• 2013

Islanding in a gird connected inverter of wind power generation system may influence a bad effect on equipments or yield safety hazards on grid so it should be detected rapidly and exactly. A passive method to detect islanding is comparatively simpler than an active method but suffers from non detection zone (NDZ). On the other hand, the active method can significantly reduce NDZ by injecting a disturbance into inverter output. To improve the reliability of islanding detection, this paper proposes a hybrid anti-islanding detection method combining the conventional passive method as well as the active method based on novel harmonic injection method using fourier transform. The proposed scheme is fast to detect islanding when NDZ does not exist because it has the nature of passive method. Under NDZ, the active method can detect occurrence of islanding reliably. The effectiveness and validity of the proposed scheme is proved through comparative simulations.

• 대한물리의학회지
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• 제17권3호
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• pp.79-86
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• 2022

PURPOSE: By virtue of its location, the iliopsoas muscle has the potential to affect the function of the diaphragm. Therefore, the purpose of this study was to investigate the effects of passive stretching of the iliopsoas muscles on pulmonary function. METHODS: Twenty male university students participated in this study. Subjects with low back pain, negative results on the modified Thomas test, and chest breathing patterns not directly related to the function of the iliopsoas muscles were excluded from this study. A digital pulmonary function measuring device (Pony FX, COSMED Inc, Italy) was used to test pulmonary function. The test was performed three times: the first test before passive stretching, the second test 10 minutes after the first test, and the third after passive stretching. Passive stretching was performed 5 times for each of the left and right iliopsoas muscles. Passive stretching was carried out for 20 seconds followed by a 10-second break. The SPSSWIN (ver. 27.0) statistics program was used for data analysis, and the significance level was α =.05. RESULTS: Among slow vital capacity (SVC) parameters, tidal volume (VT), inspiratory reserve volume (IRV), inspiratory capacity (IC) and vital capacity (VC) improved significantly after passive stretching. Also, among the maximal effort vital capacity (MEVC) parameters, forced vital capacity(FVC) and forced expiratory volume in one second(FEV1) improved significantly after passive stretching. CONCLUSION: The results showed that among the various pulmonary function parameters measured, passive stretching of the iliopsoas muscles can improve the SVC and MEVC. Therefore, passive stretching of the iliopsoas muscles may be considered for use as a treatment method to improve pulmonary function.