• 상하수도학회지
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• 제18권4호
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• pp.480-485
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• 2004

Fatty acid methyl ester (FAME) technology was evaluated as a monitoring tool for quantification of Nocardia amarae causing a nuisance foaming problem in activated sludge process. The identified signature peak was 19:1 alcohol as a reliable unique peak to N. amarae. Chemostat study revealed that the distribution and quantity of fatty acid peaks were dependent on the growth stage of Nocardia. The FAME results were similar for two relatively high dilution rates; however, the amounts of signature peaks extracted from the 4 and 6 day cultures were significantly higher. This dependence of signature peaks on the physiological state of the organism may be a useful information to assess the health of microbial populations in activated sludge. A laboratory scale batch foaming potential experiment provided a critical foaming level depending on Nocardia population. This critical Nocardia level determined in this study was in terms of either the threshold filament intersections number or the threshold signature FAME amount. The threshold peak area of signature FAME (19:1 alcohol) and corresponding filament counts were 430PA/mg VSS and $1.45{\times}10^6$ intersections/g VSS, respectively. The threshold signature FAME level could be effectively applied as a criterion for diagnosing foam occurrence in activated sludge system.

• Physical Therapy Rehabilitation Science
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• 제10권3호
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• pp.311-319
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• 2021

Objective: To investigate the effect of emphasized initial contact by using a wearable air-pressure insole to provide auditory-feedback with variations of maximum peak pressure (MPP) of the affected side on spatiotemporal gait parameters and gait symmetry of stroke patients Design: A cross-sectional study Methods: Eighteen stroke patients participated in this study. All subjects walked five trials using an air-pressure insole that provides auditory feedback with different thresholds set on the insole. First, subjects walked without any auditory feedback. Then, the MPP threshold on the affected side was set from 70% and increase threshold by 10% after each trial until 100%. They walked three times or more on the gait analyzer for each trial, and the average values were measured. Before starting the experiment, subjects measured body weight, initial gait abilities and affected side MPP without auditory feedback. Results: Temporal and spatial variables were significantly increased in trials with auditory feedback from air-pressure insole except for non-paralyzed single support time and spatial gait symmetry compared to trials without auditory feedback(p<0.05). Among the four different thresholds, the walking speed, unaffected side single support time, affected and unaffected side stride, and affected side step length were greatest at 80% threshold of maximum peak, while affected single support time, temporal gait symmetry, and unaffected step length were greatest at the maximum peak of 100% threshold. Conclusions: These results indicate that auditory feedback gait using air-pressure insoles can be an effective way to improve walking speed, single support time, step length, stride, and temporal gait symmetry in stroke patients.

• 한국정보통신학회논문지
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• 제21권7호
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• pp.1420-1428
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• 2017

R파 검출에 사용되는 여러 심전도 데이터베이스는 샘플링 주파수의 차이로 인해 서로 다른 환경에 적용할 경우 성능에 변화가 많아 알고리즘의 신뢰도를 보장하기 어렵다. 본 연구에서는 심전도신호의 샘플링 주파수에 따른 R파 검출의 최적 문턱치 설정 방법을 제안한다. 이를 위해 미분 기반의 이동평균과 제곱합수를 이용하여 전처리를 수행하였다. 이후 샘플링 주파수에 따라 피크 문턱치에 대한 최적 값을 검출하였다. 문턱치 단계는 신호의 변화와 이전 검출된 피크 값에 따라 문턱치를 변경함으로써 최적의 성능을 나타내는 값을 선정하는 과정으로 실험하였다. 제안한 방법의 우수성을 입증하기 위해 부정맥 데이터베이스 레코드를 대상으로 실험한 결과 MIT-BIH 샘플링 주파수 360Hz에 대한 미분 구간($N_d$), 윈도우 사이즈(N), 문턱 계수($p_{th}$)의 최적 값은 각각 7, 8, 6.6일 때 R파 검출율은 99.758%의 우수한 성능을 나타내었다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제14권4호
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• pp.305-312
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• 2014

This paper discusses real-time peak shaving algorithms for a large-scale battery energy storage system (BESS). Although several transmission and distribution functions could be implemented for diverse purposes in BESS applications, this paper focuses on a real-time peak shaving algorithm for an energy time shift, considering wind power generation. In a high wind penetration environment, the effective load levels obtained by subtracting the wind generation from the load time series at each long-term cycle time unit are needed for efficient peak shaving. However, errors can exist in the forecast load and wind generation levels, and the real-time peak shaving operation might require a method for wind generation that includes comparatively large forecasting errors. To effectively deal with the errors of wind generation forecasting, this paper proposes a real-time peak shaving algorithm for threshold value-based peak shaving that considers fuzzy wind power generation.

• 대한전자공학회논문지
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• 제17권2호
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• pp.10-14
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• 1980

본 논문에서는 DH-laser diode의 threshold current를 계산하기 위하여 2차고조파 왜곡 (se cond harmonic distortion)에 대해 Rate 방정식 (Rate-equation)을 동적상태와 정적상태 방정식으로 연릴하여 계산하였다. 특히 고조파 왜곡 ( )을 계산하는데 바이어스 전류 에 대하여 변조 전류 을 변조계수 m으로 놓고 (Jm=mJo)계산하여 주입전류 J가 Jth에서 2차 고조파 왜곡이 최대치를 가짐을 보여 ,이제까지 알려진 Jth조사 방법보다 간편하고 정확하게 조사할 수 있음을 제시하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.65-68
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• 2003

3GPP's RLC protocol specification adopted an error control scheme based on selective repeat ARQ. In 3GPP ARQ, distinctive windows are provide at transmitting and receiving stations so that those stations are prohibited to send or receive data PDU's out of window. An increase in window size enhances delay performance. Such an increase, however, raises the occupancy at reordering buffer, which results in a long reordering time. Aiming at suppressing the occupancy at reordering buffer, we propose a occupancy control scheme in this paper. In this scheme, a threshold is created in the receiving station's window and a data PDU out of the threshold (but within the window) is treated according to go back N ARQ. By the employment of the occupancy control scheme, the occupancy at the reordering buffer is apparently reduced, while the delay performance may be degraded due to the properties of go back N ARQ. We, thus, investigate the peak occupancy and mean delay performance by a simulation method. From numerical examples, we observe a trade-off in both performance measures and conclude that the peak occupancy is effectively reduced by setting a proper threshold under a constraint on mean delay performance.

• Earthquakes and Structures
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• 제20권4호
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• pp.457-471
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• 2021

This study aims at providing a simple and effective methodology to define a meaningful characteristic period for special class of earthquake records named "pulse-like ground motions". In the proposed method, continuous wavelet transform is employed to extract the large pulse of ground motions. Then, Fourier amplitude spectra obtained from the original ground motion and the residual motion is simply compared. This comparison permits to define a threshold pulse-period (Tp∗) as the threshold period above which the pulse component has negligible contributions to the Fourier amplitude spectrum. The effect of pulse on frequency content of motions was discussed on the light of this definition. The advantage and superior features of the new definition were related to the inelastic displacement ratio (IDR) for single-degree-of-freedom systems with period equal to one half of the threshold period. Analyses performed for the proposed period at three ductility levels u=2,4,6 were compared with the results obtained at half of pulse period derived from wavelet analysis, peak-point method and the peak of product of the velocity and the displacement response spectra (Sv x Sd). According to the results, pulse effects on inelastic displacement ratio seem to be more important when $\frac{T_p^*}{T}=2$ (T is the fundamental vibration period of system). The results showed that utilizing of the proposed definition could facilitate an enhanced understanding of pulse-like records features.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권3호
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• pp.331-338
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• 2014

A charge-pump circuit using a current-bypass technique, which suppresses charge sharing and reduces the sub-threshold currents, helps to decrease phase-locked loop (PLL) jitter without resorting to a feedback amplifier. The PLL shows no stability issues and no power-up problems, which may occur when a feedback amplifier is used. The PLL is implemented in 0.11-${\mu}m$ CMOS technology to achieve 0.856-ps RMS and 8.75-ps peak-to-peak jitter, which is almost independent of ambient temperature while consuming 4 mW from a 1.2-V supply.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.1148-1159
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• 2014

Different procedures for estimation of the extreme global wave hydroelastic responses in ships are discussed. Firstly, stochastic procedures for application in detailed numerical studies (CFD) are outlined. The use of the First Order Reliability Method (FORM) to generate critical wave episodes of short duration, less than 1 minute, with prescribed probability content is discussed for use in extreme response predictions including hydroelastic behaviour and slamming load events. The possibility of combining FORM results with Monte Carlo simulations is discussed for faster but still very accurate estimation of extreme responses. Secondly, stochastic procedures using measured time series of responses as input are considered. The Peak-over-Threshold procedure and the Weibull fitting are applied and discussed for the extreme value predictions including possible corrections for clustering effects.

• Journal of information and communication convergence engineering
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• 제9권6호
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• pp.763-768
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• 2011

Image denoising is a lively research field. Today the researches are focus on the wavelet domain especially using wavelet threshold method. We proposed an adaptive threshold method which considering the characteristic of different sub-band, the method is adaptive to each sub-band. Experiment results show that the proposed method extracts white Gaussian noise from original signals in each step scale and eliminates the noise effectively. In addition, the method also preserves the detail information of the original image, obtaining superior quality image with higher peak signal to noise ratio(PSNR).