• 한국유체기계학회 논문집
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• 제11권3호
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• pp.50-55
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• 2008

The diverter system is a key component in achieving a high accuracy liquid flow rate standard using a static gravimetric system with a flying start and stop method. The diverter is a moving device used to direct flow alternately along its normal course(by pass) or towards the weighing tank. The time needed for collection into the weighing tank is measured using a timer. So it is important to the diversion period is sufficiently fast and triggering point of timer which is determined the filling time. On this studies show that uncertainty of diverter system for changing diversion speed and triggering point was estimated in accordance with Guide to The Expression of Uncertainty in Measurement(ISO).

• ETRI Journal
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• 제46권4호
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• pp.633-647
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• 2024

In e-commerce platforms, sentiment analysis on an enormous number of user reviews efficiently enhances user satisfaction. In this article, an automated product recommendation system is developed based on machine and deep-learning models. In the initial step, the text data are acquired from the Amazon Product Reviews dataset, which includes 60 000 customer reviews with 14 806 neutral reviews, 19 567 negative reviews, and 25 627 positive reviews. Further, the text data denoising is carried out using techniques such as stop word removal, stemming, segregation, lemmatization, and tokenization. Removing stop-words (duplicate and inconsistent text) and other denoising techniques improves the classification performance and decreases the training time of the model. Next, vectorization is accomplished utilizing the term frequency-inverse document frequency technique, which converts denoised text to numerical vectors for faster code execution. The obtained feature vectors are given to the modified convolutional neural network model for sentiment analysis on e-commerce platforms. The empirical result shows that the proposed model obtained a mean accuracy of 97.40% on the APR dataset.

• Journal of information and communication convergence engineering
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• 제21권3호
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• pp.198-207
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• 2023

Responding to changes in artificial intelligence models and the data environment is crucial for increasing data-learning accuracy and inference stability of industrial applications. A learning model that is overfitted to specific training data leads to poor learning performance and a deterioration in flexibility. Therefore, an early stopping technique is used to stop learning at an appropriate time. However, this technique does not consider the homogeneity and independence of the data collected by heterogeneous nodes in a differential network environment, thus resulting in low learning accuracy and degradation of system performance. In this study, the generalization performance of neural networks is maximized, whereas the effect of the homogeneity of datasets is minimized by achieving an accuracy of 99.7%. This corresponds to a decrease in delay time by a factor of 2.33 and improvement in performance by a factor of 2.5 compared with the conventional method.

• 한국ITS학회 논문지
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• 제18권6호
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• pp.11-30
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• 2019

교통카드 데이터는 다양한 대중교통 통계 지표 산출, 정책 및 평가를 위한 자료로 활용되어 그 활용범위가 상당히 높다. 그러나 교통카드 데이터 내 주요 문제점은 하차 정류장에서 태그를 안 하고 하차하는 경우가 대부분으로 이는 교통카드 이용자의 불완전한 OD 통행 자료로 활용범위에 있어 한계가 있다. 본 연구는 의사결정 모델 기반 교통카드 데이터 하차 정류장 추정 방법을 적용한 결과 오차 범위 2개 정류장 이하에서 하차 정류장 추정 정확도는 89.7%으로 분석되었다. 이를 통하여 교통카드 데이터의 불완전성을 해소함으로써 다양한 대중교통 분석 및 평가 등에 대한 기초 자료로 활용 될 수 있을 것으로 판단된다.

• 음성과학
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• 제12권3호
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• pp.139-151
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• 2005

Previous studies have shown that Korean students have difficulty identifying some English consonants which are not in the Korean sound inventory. The aim of this study was to examine the accuracy rate of English consonants correctly identified by 130 college students in order to find out which English consonants were difficult for the students to perceive. The subject's task was to identify one of the minimal pairs played in a quiet laboratory classroom. 100 minimal pairs consisted of syllables with various onsets or codas: stops, fricatives, affricates, liquids and nasals. Results were as follows: First, the average score of the English major group was significantly higher than that of the non-English major group. Second, there was a similar distribution in the rank order of minimal pairs sorted by the accuracy rate between the two groups. Third, the accuracy rate systematically decreased as each score range decreased. Fourth, the students showed higher accuracy in the perception of liquids than that of the stop-fricative contrast. Fifth, the accuracy score in onset position was higher than in coda position. Finally, the students still had problem telling voiced consonants from voiceless ones, especially in coda position. It would be desirable to extend the present research to middle or high school students to fundamentally resolve those listening problems.

• 한국해양공학회지
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• 제16권1호
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• pp.22-26
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• 2002

In this paper, a finite element method is applied to the numerical calculation of the harbor calmness. The mild stop equation as the basic equation is used. The key of this model is that the bottom friction and boundary absorption are imposed. A numerical result is presented and compared with the results obtained from the other numerical analysis. These results are in very well agreement. This method calculating the calmness can be broadly utilized making the new design of harbor and fishing port in the future.

• 한국항공우주학회지
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• 제39권8호
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• pp.796-803
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• 2011

정지 상태에서 관성항법장치를 구성하는 가속도계 및 자이로 측정치를 이용하여 초기 자세를 구하는 것을 초기정렬 혹은 자가정렬이라 한다. 초기정렬의 정밀도는 관성항법장치에 탑재되는 관성센서의 성능에 의하여 결정되며 수평축 자세는 수평축 가속도계, 수직축 자세는 E축 자이로 성능에 의해 결정된다. 그러므로 관성센서에서 발생된 불확실한 오차는 초기정렬의 정밀도를 저하시키는 주요원인이 된다. 논 논문에서는 관성센서의 불확실한 오차 중에서 관성항법장치에 전원이 인가되어 온도가 안정화 되는 상태에서의 관성센서 오차가 초기정렬 성능에 어떠한 영향을 미치는 가를 이론적으로 분석하고 시뮬레이션을 통하여 검증한 결과를 제시한다.

• 구강회복응용과학지
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• 제35권2호
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• pp.55-63
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• 2019

본 논문은 기존에 선행되었던 연구들을 바탕으로 디지털 모형의 정확도를 평가하는 여러 가지 방법에 관하여 정리하였다. 디지털 모형의 정확도 평가 시, 시험자 교육과 인공적 지표의 사용을 통해 오차를 줄일 수 있다. 디지털 치아 모형의 정확도 평가법은 크게 선형 측정법, 2차원 단면 분석법, 3차원 최적합 분석법으로 분류할 수 있다. 스캐너의 기술이 발전함에 따라 디지털 인상 기술과 전통적 인상법의 정확도를 비교하는 많은 연구들이 이루어지고 있다. 다양한 방법을 이용하여 디지털 모형의 정확도를 평가할 수 있으며, 앞으로 스캐너의 기술 향상 및 3차원 모형 분석 소프트웨어의 개발에 따라 디지털 모형의 정확도 평가 방법이 더욱 효과적으로 변화할 것이라 생각된다. 이 논문에서는 디지털 모형의 정확도를 평가하는 방법들에 대해 소개하고, 각각의 상황에 따른 효과적인 정확도 분석법에 대해 알아보고자 한다.

• 대한음성학회지:말소리
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• 제48호
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• pp.1-17
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• 2003

Among the types of dysarthria, spastic and flaccid types are the most prominent manifestations. The objectives of the present research are (1) to discover the phonetic contrasts that differentiate spastic dysarthria from flaccid dysarthria, (2) to analyze the degrees of predictability of each phonetic contrast for intelligibility in spastic and flaccid dysarthrias and to compare them. The 'phonemic contrast word intelligibility pairs' for dysarthric speakers were tested and proved to be useful for clinical assessment of and research on dysarthria. In the group of spastic type, it showed that initial fricative vs. affricate and front vs. back vowel contrasts are transmitted relatively less effectively than flaccid type. In the group of flaccid type, initial glottal vs null contrast is transmitted less effectively than spastic type. The overall intelligibility of spastic dysarthria was predicted by multiple regression analysis with 88% accuracy by three phonetic contrasts(initial fricative vs. affricate; front vs. back vowels; initial consonant correlates). And the intelligibility of flaccid dysarthria was predicted by two phonetic contrasts(initial nasal vs. stop, front vs. back vowels) with 60% accuracy.

• 음성과학
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• 제8권3호
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• pp.185-200
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• 2001

This study was designed to investigate the treatment, generalization, and maintenance effects of vocal relaxation treatment on compensatory articulation(i.e., glottalization of plosive sound) of three children with cleft palate. Multiple baseline design was applied to evaluate treatment, generalization, and maintenance effects. The targeted phonemes were ph/, th/, /t/ which Were frequently substituted by glottal stop sounds. The main component of the treatment program was vocal relaxation using humming and aspiration sound /h/. The following conclusions were deduced from the results: (1) the treatment program for compensatory articulation was effective in facilitating correct production of targeted phoneme and eliminating glottalization for all subjects, (2) the treatment effects on articulation accuracy were generalized to untreated phonemes (/c/, /c$c^{h}$/) for 2 subjects, (3) the treatment effects on decrease of glottalization were generalized to untreated phonemes for all subjects, and (4) the treatment effects were maintained for all subjects for 2 weeks after treatment was terminated.