• Wind and Structures
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• 제3권3호
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• pp.159-175
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• 2000

Many practical time series, including pressure signals measured on roof-corners of low-rise buildings in quartering winds, consist of relatively quiescent periods interrupted by intermittent transients. The dyadic wavelet transform is used to detect these transients in pressure time series and a relatively simple pattern classification scheme is used to detect underlying structure in these transients. Statistical analysis of the resulting pattern classes yields a library of signal "building blocks", which are useful for detailed characterization of transients inherent to the signals being analyzed.

• Journal of Advanced Marine Engineering and Technology
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• 제31권3호
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• pp.235-242
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• 2007

This paper discusses dynamic characteristics of a urea-SCR (Selective Catalytic Reduction) system. The urea flow rate to improve NOx conversion efficiency is generally determined by parameters such as catalyst temperature and space velocity. The urea-SCR system was tested in the various engine operating conditions governing the raw NOx emission levels, space velocity. and SCR catalyst temperature. These experiments include cold-transients to determine catalyst light-off temperature and urea flow rate transients. Likewise. ammonia storage dynamics was also investigated. The cold-transient results indicate the light-off temperature of the catalysts used in these experiments was $200-220^{\circ}C$. The ammonia storage and urea flow rate transients all indicate very slow dynamics (on the order of seconds) which presents control challenges for mobile applications. The results presented in this paper should provide an excellent starting point in developing a functional in-vehicle urea-SCR system.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.297-303
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• 2012

This paper presents the simulation results for the analysis of a lightning surge, switching transients and very fast transients within a thermal plant. The modeling of gas insulated substations (GIS) makes use of electrical equivalent circuits that are composed of lumped elements and distributed parameter lines. The system model also includes some generators, transformers, and low voltage circuits such as 24V DC rectifiers and control circuits. This paper shows the simulation results, via EMTP (Electro-Magnetic Transients Program), for three overvoltage types, such as transient overvoltages, switching transients, very fast transients and a lightning surge.

• Journal of Electrical Engineering and Technology
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• 제3권1호
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• pp.36-42
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• 2008

In a gas insulated substation (GIS), Very Fast Transient Over-voltages (VFTOs) are generated due to switching operations and ground faults. These fast transients are associated with high frequency components of the order of a few hundreds of MHz. These transients may cause internal faults i.e., layer-to-layer faults or minor faults in a capacitively graded bushing, which is one of the important pieces of terminal equipment for GIS. In the present study, the PSPICE model has been developed to calculate the voltage distribution across the layers of 420kV graded bushing for high frequency pulses of rise time 1 to 50ns, which simulate the VFTO. For this simulation, an equivalent electrical network of bushing with different equivalent layers has been considered. The effect of different equivalent layers modeling circuits on the non-uniform voltage factor has been analysed. The influence of copper strip inductance on voltage distribution across layers has also been analysed for various rise times of high frequency transients. Finally, the leakage current of the bushing is calculated for evaluating the bushing condition under these transients.

• 한국환경과학회지
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• 제14권4호
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• pp.389-395
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• 2005

The changes of O-J-I-P transients were investigated using leaves of four subtropical plant species (Crinum asiaticum var. japonicum, Osmanthus insularis, Chloranthus glaber and Asplenium antiquum) under the natural conditions in winter, in order to select the stress indicators for diagnosing physiological states of plants under low temperature. In the O-J-I-P transients of these species, the fluorescence intensity was found to be higher in O-step and lower in P-step in winter than in summer. Particularly, the fluorescence intensity of the P-step in Crinum asiaticum var. japonicum was lower than those of other three plant species, indicating that Crinum asiaticum var. japonicum is the most sensitive to low temperature. Of the chlorophyll fluorescence parameters derived from O-J-I-P transients of four subtropical plants, Fm, Fv/Fo, ABS/CS, TRo/CS, $\phi_{po}$ and $\phi_{po}/(1-\phi_{po})$ decreased significantly with the increase of Fo, Sm, N, EToICS, ETo/RC and $\psi_o/(1-\psi_o)$ depending on temperature drop in winter. Therefore, these parameters could be used as indicators for estimating low temperature stress and diagnosing physiological states of plants under the natural conditions in winter.

• Archives of Pharmacal Research
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• 제22권2호
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• pp.119-123
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• 1999

Parathyroid hormone (PTH) treatment of bone and kidney-derived cells not only activates adenyly cyclase buy also increases intracellular free calcium, and translocates protein kinase C (PKC) from cytosol to plasma membranes. We have found that acute phorbol ester pretreatment significantly decreases PTH-induced calcium transients and the effect of phorbol ester was antagonized by staurosporine (ST). Although the major effect of ST in that study was the reversal of the action of phorbol ester, it appeared that ST may also have promoted the effect of PTH directly. To further investigate the observation, we examined the effect of ST on the intracellular calcium transients induced by PTH and $\alpha$-thrombin ($\alpha$-TH). For calcium transient experiments, UMR-106 cells were loaded with 2 mM fluo-acetoxymethylester for 30 min at room temperature. The cells were then washed and suspended in buffer containing 1 mM calcium. Fluorescence was detected at 530 nm, with excitation at 505 nm. ST alone did not cause calcium transients, but enhanced the transients elicited by PTH response. added 5 min before the hormone. Another protein kinase inhibitor H-7 likewise enhanced the calcium responses elicited by PTH, while genistein did not affect PTH response. Calcium transients elicited by $\alpha$-TH were also enhanced by ST. The results suggest that there might be tonically activated endogenous protein kinase(s) which inhibit calcium signaling of some calcemic agents.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1990년도 추계학술대회 논문집
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• pp.47-51
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• 1990

This paper deals with the electric field sensor. A capacitive voltage sensor is designed and manufactured for measuring the very fast transients generated by operating disconnection switch in GIS. It is certified that the voltage sensor has a good specific characteristic in high frequency domain and is able to measure the very fast transients included the harmonic components of 200[MHz].

• 오토저널
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• 제14권2호
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• pp.44-53
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• 1992

Automotive transmission is the principle component of vehicle driving system, which transmits the adjusted engine power. The automation of transmission arises from the annoyance of transmission operation such as the frequent stop/start of vehicle and the shifting transients. The study on the optimal shifting condition for the automation of transmission needs the investigation of shifting transients. However, the dynamic modeling theory during transient period is not well-established. In this study, the techniques of dynamic modeling for the power transmission system with Merrite-Wilson gear train are presented. To predict the shifting transients, a driving simulation program is developed, and the results of the analysis are cross-checked in the field test.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.365-367
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• 2005

Power system transients cause problems and disturbances that might be harmful to generators. However, very little have been done to systematically understand and analyze power system transients. There is also a lack of computational effective methods as transients are short and associated with a wide range of events and system conditions. This paper addresses to propose a signal processing method, ESPRIT, for the analysis of a range of transients due to disturbance. Experimental results are included to evaluate the usefulness of ESPRIT in power system transient analysis.

• 한국광학회지
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• 제8권6호
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• pp.471-475
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• 1997

본 논문에서는 에르븀 첨가 광섬유 증폭기를 이용하여 단일 채널을 증폭할 때의 이득 동특성(gain dynamics)과 다채널을 증폭할 때의 이득 동특성에 대해 논의하였다. 여러 개의 에르븀 첨가 광섬유 증폭기가 연결된 증폭기 체인에서 채널 수의 변화에 의해 입력 광파워가 변할 때의 출력 광파워의 과도 현상(power transients)을 측정하고, 이를 $\mu\textrm{s}$ 이하의 응답 시간을 갖는 펌프 광파워 조절 회로를 이용하여 억제하였다.