• 대한조선학회논문집
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• 제47권6호
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• pp.808-812
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• 2010

This paper studies the finite element modeling and analytical parameters for the numerical evaluation of dynamic stiffness of large foundation for shipboard equipments such as marine diesel engine. For the purpose, numerical method and procedure to evaluate the dynamic stiffness are established based on the impact test method, which are applied for the dynamic stiffness evaluation of a real diesel generator foundation of ship. Numerical investigations compared with the measured data are carried out to evaluate the effects of modeling ranges of ship substructure, finite element sizes, lower support structures and damping coefficients. From the results, modeling and analytical parameters for proper evaluation of dynamic stiffness of large foundation of shipboard equipment are suggested.

• Journal of Biosystems Engineering
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• 제22권4호
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• pp.433-438
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• 1997

The freshness of apple was evaluated by characterizing the surface texture of flesh cells. The freshness index which was related to the amount of wrinkles on the cell surface was defined to quantify the freshness. Four parameters relevant to the amount of the cell wrinkles were selected and measured using image analysis including wrinkle extraction procedure and Fast Fourier Transform of a wrinkle-extracted image. Out of 4 parameters, three parameters had highly significant correlations with the time elapsed after harvest. But it was concluded that two parameters out of such 3 parameters could be used for description of freshness index.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.52-57
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• 2004

해체부지 선량평가 모델의 주요 핵종에 대한 key parameter를 분석하기 위하여 민감도 분석을 수행하였다. 본 연구에서 민감도 분석을 수행하기 위한 주요 가정 사항으로서 피폭시나리오는 가장 보수적인 resident farmer를 그리고 방사성핵종의 오염 정도는 0.037 Bq/g로 하였다. 분석결과, 감마 방출 핵종인 Cs-137과 Co-60의 경우에는 오염지역의 면적과 거주관련 변수(외부감마차폐인자와 실내 거주시간분율), C-14 핵종의 경우에는 환경변수와 불포화층의 수문학적 변수가, Sr-90 핵종의 경우에는 오염지역의 토양 밀도가 선량에 미치는 영향이 큰 parameter로 확인되었다.

• 한국농공학회지
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• 제40권2호
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• pp.59-68
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• 1998

This study was conducted to derive optimal design floods by generalized gamma distribution model of the annual maximum series at eight watersheds along Geum, Yeongsan and Seomjin river systems. Design floods obtained by different methods for evaluation of parameters and for plotting positions in the generalized gamma distribution model were compared by the relative mean errors and graphical fit along with 95% confidence limits plotted on gamma probability paper. The results were analyzed and summarized as follows. 1. Basic statistics and parameters were calculated by the generalized gamma distribution model using different methods for parameters. 2. Design floods according to the return periods were obtained by different methods for evaluation of parameters and for plotting positions in the generalized gamma distribution model. 3. It was found that design floods derived by sundry averages method for parameters and Cunnane method for plotting position in the generalized gamma distribution are much closer to those of the observed data in comparison with those obtained by the other methods for parameters and for plotting positions from the viewpoint of relative mean errors. 4. Reliability of design floods derived by sundry averages method in the generalized gamma distribution was acknowledged within 95% confidence interval.

• 말소리와 음성과학
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• 제1권3호
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• pp.133-144
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• 2009

Pharyngeal flap surgery changes the space and shape of the oral cavity and vocal tract, and these changing conditions bring resonance change. The purpose of this study was to determine the most reliable and valuable parameters for evaluating hypernasality to distinguish two patients before and after pharyngeal flap surgery. Each patient was asked to clearly speak the vowels /a/, /i/, /u/, /e/, /o/ for voice recording. There were nine parameters: Formant (F1, F2, F3), Bandwidth (BW1, BW2, BW3), LPC energy slope ($\Delta$ |A2-A1/F2-F1|), and Band Energy (0-500 Hz, 500-1000 Hz) by each vowel. From the results of discrimination analyses on acoustic parameters, the vowels /a/, /e/ appeared to be insignificant but vowels /i/, /u/, /o/ appeared to be efficient in the separation. A 95%, 100%, and 100% recognition score could be reached when vowels /i/, /u/, and /o/ were analyzed. The results showed that F2, BW3, and LPC slope are more important parameters than the others. Finally, there is a relation between perceptual evaluation score and LPC energy slope of acoustic parameters by least square slope.

• Earthquakes and Structures
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• 제16권2호
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• pp.197-208
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• 2019

The objective of this study is to propose new seismic intensity parameters based on the Hilbert spectrum and to associate them with the seismic damage potential. In recent years the assessment of even more seismic features derived from the seismic acceleration time-histories was associated with the structural damage. For a better insight into the complex seismic acceleration time-history, Hilbert-Huang Transform (HHT) analysis is utilized for its processing, and the Hilbert spectrum is obtained. New proposed seismic intensity parameters based on the Hilbert spectrum are derived. The aim is to achieve a significant estimation of the seismic damage potential on structures from the proposed new intensity parameters confirmed by statistical methods. Park-Ang overall structural damage index is used to describe the postseismic damage status of structures. Thus, a set of recorded seismic accelerograms from all over the word is applied on a reinforced concrete frame structure, and the Park-Ang indices through nonlinear dynamic analysis are provided and considered subsequently as reference numerical values. Conventional seismic parameters, with well-known seismic structural damage interrelation, are evaluated for the same set of excitations. Statistical procedures, namely correlation study and multilinear regression analysis, are applied on the set of the conventional parameters and the set of proposed new parameters separately, to confirm their interrelation with the seismic structural damage. The regression models are used for the evaluation of the structural damage indices for every set of parameters, respectively. The predicted numerical values of the structural damage indices evaluated from the two sets of seismic intensity parameters are inter-compared with the reference values. The numerical results confirm the ability of the proposed Hilbert spectrum based new seismic intensity parameters to approximate the postseismic structural damage with a smaller Standard Error of Estimation than this accomplished of the conventional ones.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.710-715
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• 2004

To evaluate the fatigue lifetime of structures, it is necessary to identify the value of parameters through tests or literature. it is difficult for field engineers to get the necessary data through tests from the viewpoint of time and cost. In this study. we surveyed literature and proposed a procedure to identify the fatigue parameters for fatigue life evaluation by local strain approach.

• 한국공작기계학회논문집
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• 제14권3호
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• pp.38-46
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• 2005

The destructive method is reliable and widely used for the estimation of material degradation but it have time-consuming and a great difficulty in preparing specimens from in-service industrial facilities. Therefore, the estimation of degraded structural materials used at high temperature by nondestructive evaluation such as electric resistance method, replica method, Barkhausen noise method, electro-chemical method and ultrasonic method are strongly desired. In this study, various nondestructive evaluation(NDE) parameters of the Barkhausen noise method, such as MPA(Maximum Peak Amplitude), RMS, IABNS(Internal Area of Barkhausen Noise on Signal) and average amplitude of frequency spectrum are investigated and correlated with thermal damage level of 2.25cr-1.0Mo steel using wavelet analysis. Those parameters tend to increase while thermal degradation proceeds. It also turns out that the wavelet technique can help to reduce experimental false call in data analysis.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2007년도 제34회 KOSCO SYMPOSIUM 논문집
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• pp.98-103
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• 2007

The number of vehicles employing diesel engines is rapidly rising. Accompanying this trend, application of an after-treatment system is strictly required as a result of reinforced exhaust regulations. The Diesel Particulate Filter (DPF) system is considered as the most efficient method to reduce particulate matter (PM), but the improvement of a regeneration performance at any engine operation point presents a considerable challenge by itself. Temperature, gas compostion and flow rate of exhaust gas are important parameters in DPF evaluation, especially regeneration process. Engine dynamometer and degment tester are generally used in DPF evaluation so far. But these test method couldn't reveal the effect of various parameters on real DPF, such as O2 concentration, amount of soot and exhaust gas temperature. This research has studied the possibility using dump combustor that used to take an approach lean premixed combustion in gas turbine for a DPF power and optimized. It is possible that utilize the system as DOC (Diesel Oxidation Catalyst) and SCR(Selective Catalytic Reduction) assessments test as well as DPF evaluation

• 대한임베디드공학회논문지
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• 제16권6호
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• pp.241-246
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• 2021

In this paper, we developed the evaluation system for the active noise control so that the algorithms can be easily evaluated in real-time on the system. We implemented the active noise controller based on a single-chip with only additional op-amps for signal conditioning because the TMS320C280049 MCU includes almost all necessary peripherals for the active noise controller. Due to the difficulty in testing algorithms on embedded-type hardware unlike in computer simulation, we also developed GUI-based evaluation software which makes it simple to test algorithms on the hardware. Using the GUI software, we can optimize the parameters of the algorithms with ease in a specific noise environment because the parameters can be adjusted in real-time when the algorithm is running on the hardware.