• 대한전기학회논문지:전력기술부문A
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• 제48권1호
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• pp.44-51
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• 1999

This paper proposes a new approach of plant fault diagnosis which is based on detecting the characteristic pattern signals and associating them with the corresponding faults. The new approach does not require analytic modeling of the target system but best reflects the expertise embedded in the experienced human operation by mimicking them in a systematic way. This paper intends to illustrate the feasibility of the proposed by developing the algorithms to detect and estimate the typical characteristic pattern signals, I. e., oscillatory patterns, and applying them to the diagnosis of various faults of a 500MW boiler control system including tube rupture, feed-water leak, and controller failure.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권2호
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• pp.923-938
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• 2019

Surge motion of top-end platform induced by periodic wave makes marine flexible riser encounter equivalent sheared-oscillatory flow, under which the Vortex-induced Vibration (VIV) response will be more complicated than pure sheared flow or oscillatory flow cases. Based on a time domain force-decomposition model, the VIV response characteristics under sheared-oscillatory flows are investigated numerically in this paper. Firstly, the adopted numerical model is validated well against laboratory experiments under sheared flow and oscillatory flow. Then, 20 sheared-oscillatory flow cases with different oscillation periods and top maximum current velocities are designed and simulated. Under long and short oscillation period cases, the structural response presents several similar features owing to the instantaneous sheared flow profile at each moment, but it also has some different patterns because of the differently varying flow field. Finally, the effects and essential mechanism of oscillation period and top maximum current velocity on VIV response are discussed systematically.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.315-317
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• 2003

Neural oscillator is applied in oscillatory systems (Analysis of image information, Voice recognition. Etc...). If we apply established EBPA(Error back Propagation Algorithm) to oscillatory system, we are difficult to presume complicated input's patterns. Therefore, it requires more data at training, and approximation of convergent speed is difficult. In this paper, I studied the neural oscillator as synchronized states with appropriate phase relation between neurons and recognized the Korean alphabet using Neural Oscillator Phase model Synchronization.

• 대한기계학회논문집B
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• 제26권7호
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• pp.1014-1021
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• 2002

Analysis of two-dimensional secondary flows given by an oscillatory motion of a liquid with a free surface in a rectangular container subject to a linear reciprocating force is performed by numerical and experimental methods. FVM is used for the numerical computation of the two-dimensional flows. We considered the effects of the free-surface properties such as the surface tension and the dilatational viscosity. The boundary-layer analysis as well as an experiment is used in establishing the free surface properties. The secondary flow patterns are visualized by a laser sheet. It is shown that the secondary flow patterns predicted by the numerical methods are in good agreement with the experimental results.

• 자원환경지질
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• 제34권5호
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• pp.437-446
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• 2001

부산 보배견운모 광상의 프로필리틱 열수변질대에서 형성된 녹염석은 다양한 누대구조를 수반하는데, 다중결정성장 누대구조, 진동누대구조, patchy누대구조 및 강도가 약한 불규칙한 누대구조가 특징적이다. 누대구조는 주로 열수용 액의 AI Fe의 활동도에 좌우되며, 전반적으로 결정의 중심부에서는 AI, 가장자리에서는 Fe의 함량이 높다. 녹염석 의 Ps는 18.5-34.3 mot.% 범위이다. 여러 결정이 중첩하여 형성된 누대구조에서는 잔류조직이 부분적으로 흡수용해 되었으며, 이후에 결정들이 새로 성장하였다. 다중결정성장 누대구조나 진동누대구조는 열수시스템의 유체의 화학조성, 산화환원전위, 온도 등과 같은 물리화학적 변수들이 급격하게 변동하였음 지시한다

• 한국해양공학회지
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• 제10권3호
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• pp.105-116
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• 1996

In this paper, we report the experimental results for the flow pattern and the material transport around a cavity subject to a sinusoidal external flow at the far region to ward the open side of the cavity. A tilting mechanism is used to generate a oscillatory flow inside a shallow rectangular container having a cavity at one side. The surface flow visualization is performed to obtain the unsteady behavior of vortices generated at two edges situated at the entrance of the cavity. It was found that at the period 4.5 sec., the behavior of the vortices is asymmetric, and there exists a steady residual flow in the cavity. The bottom flow patterns are also visualized. There are two regions outside of the cavity where the bottom fluid particles concentrate. The material transport in this flow model is very peculiar; fluid particles in the cavity flows outward through the passage along the walls starting from the edges, and particles in the outer region approach the cavity from the central region.

• 한국지능시스템학회논문지
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• 제14권1호
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• pp.93-99
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• 2004

Neural oscillator can be applied to oscillatory systems such as analyses of image information, voice recognition and etc. Conventional EBPA (Error back Propagation Algorithm) is not proper for oscillatory systems with the complicate input`s patterns because of its tedious training procedures and sluggish convergence problems. However, these problems can be easily solved by using a synchrony characteristic of neural oscillator with PLL(Phase Locked Loop) function and by using a simple Hebbian learning rule. Therefore, in this paper, a technique for Recognition of the Korean Alphabet using Phase Synchronized Neural Oscillator was introduced.

• The Korean Journal of Physiology and Pharmacology
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• 제15권6호
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• pp.415-422
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• 2011

Previously, we reported that besides retinal ganglion cell (RGC) spike, there is ~10 Hz oscillatory rhythmic activity in local field potential (LFP) in retinal degeneration model, rd1 mice. The more recently identified rd10 mice have a later onset and slower rate of photoreceptor degeneration than the rd1 mice, providing more therapeutic potential. In this study, before adapting rd10 mice as a new animal model for our electrical stimulation study, we investigated electrical characteristics of rd10 mice. From the raw waveform of recording using $8{\times}8$ microelectrode array (MEA) from in vitro-whole mount retina, RGC spikes and LFP were isolated by using different filter setting. Fourier transform was performed for detection of frequency of bursting RGC spikes and oscillatory field potential (OFP). In rd1 mice, ~10 Hz rhythmic burst of spontaneous RGC spikes is always phase-locked with the OFP and this phase-locking property is preserved regardless of postnatal ages. However, in rd10 mice, there is a strong phase-locking tendency between the spectral peak of bursting RGC spikes (~5 Hz) and the first peak of OFP (~5 Hz) across different age groups. But this phase-locking property is not robust as in rd1 retina, but maintains for a few seconds. Since rd1 and rd10 retina show phase-locking property at different frequency (~10 Hz vs. ~5 Hz), we expect different response patterns to electrical stimulus between rd1 and rd10 retina. Therefore, to extract optimal stimulation parameters in rd10 retina, first we might define selection criteria for responding rd10 ganglion cells to electrical stimulus.

• 한국광물학회지
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• 제18권3호
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• pp.227-236
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• 2005

밀양점토광상의 알루미늄이 풍부한 다이아스포아 단괴에서 열수변질 기원 전기석은 집합체나 미립으로 산출한다 대부분의 전기석 결정은 미세한 대구조가 특징적인데, 이는 열수변질 작용동안 개방계의 유체혼합과 같은 변동이 심한 환경에서 형성되었음을 지시한다. 본 전기석의 화학적 진동누대 구조의 양상은 결정축의 방향과는 무관하게 흡사한 특징을 보인다. Mg는 결정성장 초기, Fe는 후기 단계동안에 부화되었으며, Fe/Mg의 비는 규칙적으로 진동함을 보여 준다. 화학분석, 후방산란영상(BSE), X-선 화학분석도에 따르면 전기석내 진동누대구조는 Fe와 Mg 함량변화에 주로 제어되었으며 봉소함량의 기여도는 미미하다. 전기석이 다이아스포아와 딕카이트로 변질되는 것으로 볼 때 전기석은 B, Fe, Mg의 활동도가 감소하면서 이들 고알루미나 광물에 비하여 불안정해 진다. 그러므로 열수계내 알루미늄 활동도가 전기석의 안정성을 제어하는 것으로 볼 수 있다.

• Korea-Australia Rheology Journal
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• 제15권2호
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• pp.97-105
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• 2003

In the previous paper (Hyun et al.,2002), we have investigated the shape of storage modulus (G') and loss modulus (G") of complex fluids under large amplitude oscillatory shear (LAOS) flow. As the strain amplitude increases, owever, the stress curve becomes distorted and some important information may be smothered during data processing. Thus we need to investigate the stress data more precisely and systematically. In this work, we have obtained the stress data using high performance ADC (analog digital converting) card, and investigated the nonlinear response of complex fluids, 4wt% xanthan gum (XG), 2 wt% PVA/ 1 wt% Borax, and 1 wt% hyaluronic acid (HA) solutions, using Fourier transformation (FT) rheology. Comparing the strain signals in time domain with FT parameters in frequency domain, we could illustrate the sensitivity and importance of FT rheology. Diverse and unique stress patterns were observed depending on the material system as well as flow environment. It was found that they are not the outcome of experimental deficiency like wall slip but characteristics of the material system. When nonlinear response of complex fluids is analyzed, the intensity and phase angle of higher harmonic contributions should be considered together, and the shape of the stress signal was found to be strongly dependent upon phase angle.ngle.