• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.5
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• pp.134-140
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• 2003

In this paper, a hardware implementation of gas flow meter for accuracy improvement and saving repair costs at a field is investigated. An adaptive filter using LMS algorithms for estimating cavity vibration frequencies in noisy environments is also studied. The proposed cavity gas flow meter measures cavity sound signals in gas flow tube using microphone and signal processing systems estimate the cavity vibration frequency from the measured signal. The flow velocity and flow quantity can be calculated using the estimated cavity vibration frequency. Since cavity vibration frequency is corrupted by the environmental noise, an adaptive filter using NLMS algorithms is used for cancelling the environmental noise. Experiments using 1MS32OC32 digital signal processor are performed to show the effectiveness of the proposed system.

• The Journal of the Acoustical Society of Korea
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• v.13 no.1E
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• pp.11-19
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• 1994

Hidden Markov Models (HMM's) with explicit state duration density (HMM/SD) can represent the time-varying characteristics of speech signals more accurately. However, such an advantage is reduced in relatively smooth state duration densities or ling bounded duration. To solve this problem, we propose HMM's with global path constraint (HMM/GPC) where the transition between states occur only within prescribed time slots. HMM/GPC explicitly limits state durations and accurately describes the temproal structure of speech simply and efficiently. HMM's formed by combining HMM/GPC with HMM/SD are also presented (HMM/SD+GPC) and performances are compared. HMM/GPC can be implemented with slight modifications to the conventional Viterbi algorithm. HMM/GPC and HMM/SD_GPC not only show superior performance than the conventional HMM and HMM/SD but also require much less computation. In the speaket independent isolated word recognition experiments, the minimum recognition eror rate of HMM/GPC(1.6%) is 1.1% lower than the conventional HMM's and the required computation decreased about 57%.

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.643-651
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• 2008

This study was conducted to promote reliability of the simulated result for the long-term streamflow in Daecheong watershed. This system was constructed by the SSARR model that considered the effect of small scale irrigation facilities. We investigated the present condition of small scale irrigation facilities and analyzed the relation between irrigation facilities and river discharge. According to the analysis result about the effect of irrigation facilities, the error occurrence frequency was increased at the sub-basin that has many reservoirs and during the second quarter except for the 2003 year. Therefore, we created the relative equation between small irrigation facilities and river water and estimated the simulated streamflow for the main stations. Consequently, error of the runoff simulated with considering small scale irrigation facilities was decreased than that without considering small scale irrigation facilities at all.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.1
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• pp.10-17
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• 2008

The purpose of this thesis is to reduce of error for source location through acoustic emission(AE) signal, generated elastic wave from crack growth to leak for facility diagnosis. Especially, in order to overcome noise from original signal, this paper proposed enhancement of source location by using noise reduction based on wavelet transform. To evaluate actual performance in experiments, Pencil Lead Break is used crack signal source on the aluminum plate and drain valve of air compressor is used as substitute pressure vessel to generate leak signal. In signal processing, wavelet shrinkage and soft threshold are used to discriminate signal source and then source location techniques have been effectively used with group velocity using material property and time difference between sensor using cross correlation. Source location for crack and leak test have some difference, but the result show that improved 30% with a average length within 10.46mm in crack test and improved 2% compare with average filter in leak test when we applied wavelet transform.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.436-444
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• 2016

Uniformity in transducer performance is a must-have to ensure the reliable acoustic performance of a tile projector, used for active echo reduction. However, practical limitations imposed by variations in material properties and fabrication errors lead to performance variations among unit transducers, which could degrade the radiation characteristics (transmitting voltage response and directivity) of the tile projector and ultimately the echo reduction performance. In this paper we present a method to minimize these adverse effects via an appropriate placement of unit transducers within the tile projector. To this end, we perform a series of coupled acoustic-piezoelectric simulations, assuming a group of 36 unit transducers having 6 dB variations in transmitting voltage response, to analyze and compare the radiation characteristics of tile projectors under different transducer placement schemes.

• Journal of the Korean Chemical Society
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• v.59 no.4
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• pp.271-279
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• 2015

The critical micelle concentration (CMC), the counter ion binding constant (B) and the aggregation number (N^* ) for the mixed micellization of sodium dodecanoate and sodium n-octanoate as two anionic surfactants have been investigated by means of electric conductivity and light scattering. As its experimental results are found to be deviated from ideal mixed model, thus two different kinds of regular solution models such as Rubingh and Motomura are used for interpreting our experimental data. The stability of the mixed micelles has been confirmed from the negative values of the standard Gibbs energy of mixed micellization ΔG^micel,0 over all compositions and the measured values of ΔG^micel,0 agreed with the theoretical ones within the experimental error.

• Korean Journal of Remote Sensing
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• v.31 no.6
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• pp.583-598
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• 2015

This paper presents derivation of background temperature from geostationary satellite and its validation based on ground measurements and Geographic Information System (GIS) for future use in weather and surface heat variability. This study only focuses on daily and monthly brightness temperature in 2012. From the analysis of COMS Meteorological Data Processing System (CMDPS) data, we have found an error in cloud distribution of model, which used as a background temperature field, and in examining the spatial homogeneity. Excessive cloudy pixels were reconstructed by statistical reanalysis based on consistency of temperature measurement. The derived Brightness temperature has correlation of 0.95, bias of 0.66 K and RMSE of 4.88 K with ground station measurements. The relation between brightness temperature and both elevation and vegetated land cover were highly anti-correlated during warm season and daytime, but marginally correlated during cold season and nighttime. This result suggests that time varying emissivity data is required to derive land surface temperature.

• Food Engineering Progress
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• v.14 no.1
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• pp.75-79
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• 2010

Partial least square regression (PLSR) was executed on curve data of force-deformation from back extrusion test and sensory data for commercial instant noodles. Sensory attributes considered were hardness (A), springiness (B), roughness (C), adhesiveness to teeth (D), and thickness (E). Eight and two kinds of fried and non-fried instant noodles respectively were used in the tests. Changes in weighted regression coefficients were characterized as three stages: compaction, yielding, and extrusion. Correlation coefficients appeared in the order of E>D>A>B>C, root mean square error of prediction D>C>E>B>A, and relative ability of prediction D>C>E>B>A. Overall, 'D' was the best in the correlation and prediction. 'A' with poor prediction ability but high correlation was considered good when determining the order of magnitude.

• International Area Studies Review
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• v.16 no.1
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• pp.275-301
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• 2012

This study analyzes the regional disparity in India between 24 states over the period 1980 to 2009. The traditional regressive and spatial autoregressive models are used that includes measures of spatial effects. The results provide no evidence that convergence is valid in India. However, the results indicate that spatial interaction is an important element of state growth in India. The result of spatial analysis excluded two outliner states reveals more strong relationship between the weighted spatial income level and the state growth rates. Moreover, the results find that the coefficients of spatial lag of initial per capital and error terms are significantly negative. The coefficient of variation measures that the distribution of state income level has diverged over time. Therefore, this study concludes that the growth of regional state income does not have a tendency to converge rater than diverge. The results is rational because as the Indian economy is growing rapidly, some states grow faster than the others while initial poor states become the poorest ones, which increases regional disparity in India.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.402-402
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• 2021

다목적댐의 유입량은 댐 저수지 관리 및 운영에 있어 중요한 고려사항으로, 정확한 유입량을 사용하는 것이 필수적이다. 댐 저수지 유입량은 유역의 물수지분석, 홍수조절 의사결정 등 이·치수적 측면에서 활용도가 높으며, 특히 기후변화로 인한 홍수나 가뭄의 발생이 빈번해진 최근의 상황에서 위기경보 운영 등 재난관리 측면에서도 그 중요성이 높아지고 있다. 현재 우리나라에서는 댐 저수지 유입량 산정에 방류량과 저수지 수위를 활용한 물수지방정식에 의한 방법을 공식적으로 활용하고 있다. 그러나 물수지방정식을 이용하여 계산된 유입량은 평수기와 갈수기 오차가 크고 음의 유입량 값이 발생하는 등 지속적인 개선의 필요성이 제기되었다. 이를 보완하기 위해 댐 저수지 직상류부 하천의 수위 측정치로부터 수위-유량곡선을 통해 유량을 산출하고, 그 값을 활용하여 댐 방류량을 추정하는 방법이 제시되었다. 그러나 직상류부 수위 측정이 불가능한 저수지에는 활용이 어렵기 때문에 다양한 지점에 적용할 수 없다는 한계가 있다. 본 연구에서는 기존 댐 저수지 유입량 산정방식의 한계를 보완하기 위해 수위계측이 어려운 지점에서도 유량 계산이 가능한 분포형 강우-유출모형 GRM(Grid based Rainfall-runoff model)을 연구에 활용하였다. 한강권역 내 K-water 운영 다목적댐인 소양강댐, 횡성댐, 충주댐 직상류부 유량과 분포형 강우-유출모형으로 계산된 유량을 비교하여 모의 유량자료의 활용성을 검토하였다. 다음으로 댐 유입지점-상류 관측지점 간 유량의 상관관계를 분석하였으며, 이를 통해 상류 하천에 흐르는 유량으로부터 댐 유입량을 계산할 수 있는 관계곡선식을 도출하였다. 본 연구에서 제시한 댐 유입량 산정방식은 관측지점의 다양성과 결과의 정확도를 향상시킬 수 있다는 측면에서 기존 방식 개선에 활용할 수 있을 것으로 기대된다. 또한 분석 절차의 표준화나 결과에 대한 다양한 검증이 이루어진다면, 홍수 및 가뭄의 위기경보 발령에 대한 참고자료로 활용이 가능할 것으로 판단된다.