• 한국군사과학기술학회지
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• 제15권4호
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• pp.417-423
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• 2012

Radar Cross Section(RCS) is a measure of how detectable an object is with a radar. A larger RCS indicates that an object is more easily detected. Informally, the RCS of an object is the cross-sectional area of a perfectly reflecting sphere that would produce the same amount of reflection strength as the object in question would. In order to estimate RCS of aircraft weapons the external surface is modeled as a collection of simple shape elements. And the overall RCS is estimated as a vector sum of configuring elements' cross-sections which are well known given by analytic formulae. A RCS estimation code is developed for a typical shape of Air-To-Surface bombs and missiles. Size of weapons and location of fins are implemented in the code in addition to the presence of canards. The ability to predict radar return from flying vehicles becomes a critical technology issue in the development of stealth configurations. This simplified method of RCS estimation is known to be fast and accurate enough in an optical region of high frequency incident radio wave.

• 말소리와 음성과학
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• 제2권3호
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• pp.37-46
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• 2010

This study investigates acoustic characteristics of English and Korean voiceless sibilant fricatives as they appear before the three vowels, /i/, /$\alpha$/ and /u/. Three measurements - duration, center of gravity and major spectral peak - are employed to compare acoustic properties and vowel effect for each fricative sound. This study also investigates the question of whether Korean sibilant fricatives are acoustically similar to the English voiceless alveolar fricative /s/ or to the palato-alveolar /$\int$/. The results show that in the duration of frication noise, English /$\int$/ is the longest and Korean lax /s/ the shortest of the four sounds. It is also observed that English alveolar /s/ has the highest value, whereas Korean /s/ shows the lowest value in the frequency of center of gravity. In terms of major spectral peak, while English /s/ reveals the highest frequency, English /$\int$/ shows the lowest value. In addition, evidence indicates that there is a strong vowel effect in the fricative sounds of both languages, although the vowel effect patterns of the two languages are inconsistent. For instance, in the major spectral peak, both Korean lax /s/ and tense /$s^*$/ show significantly higher frequencies before the vowel /$\alpha$/ than before the other vowels, whereas both English /s/ and /$\int$/ exhibit significantly higher frequencies before the vowel /i/ than before the other vowels. These results indicate that Korean sibilant fricatives are acoustically distinct from both English /s/ and /$\int$/.

• 한국컴퓨터정보학회지
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• 제8권2호
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• pp.33-42
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• 2001

본 논문에서는 웹과 XML을 이용하여 학습자가 원하는 문항만을 검색하고 평가할 수 있는 문제은행 시스템을 구현하였다. 문항의 구성은 4지선다형, 5지선다형, 단답형으로 구성하였고 난이도 및 출제빈도를 고려하여 변별력을 가지도록 문제은행화 하였다. 문항검색은 데이터베이스에 저장된 정보를 단순히 검색하는 것이 아니라 저장된 정보를 XML문서로 변환한 후 XML 데이터에 대하여 Xpath를 이용하여 검색하였다 검색된 결과는 XSL을 이용하여 브라우저상에 나타나도록 하였다. 문항평가는 학습자가 원하는 과목. 단원에 대해서 난이도 및 출제빈도 그리고 문항유형별로 문항수를 입력하여 평가 문항을 생성하였다. 또한 실시간으로 학습자에게 학습결과를 제공하였고 학습자가 오답으로 응답한 문항에 대해서는 반복학습을 할 수 있도록 하였다.

• 신재생에너지
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• 제16권1호
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• pp.15-24
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• 2020

For mechanical load testing of wind turbines, capture matrix is constructed for various range of wind speeds according to the international standard IEC 61400-13. The conventional method wastes considerable amount of data by its invalid data policy -segment data into 10 minutes then remove invalid ones. Previously, we have suggested an alternative way to save the total amount of data to build a capture matrix, but the efficient selection of data has been still under question. The paper introduces optimization algorithms to construct capture matrix with less data. Heuristic algorithm (simple stacking and lowest frequency first), population method (particle swarm optimization) and Q-Learning accompanied with epsilon-greedy exploration are compared. All algorithms show better performance than the conventional way, where the distribution of enhancement was quite diverse. Among the algorithms, the best performance was achieved by heuristic method (lowest frequency first), and similarly by particle swarm optimization: Approximately 28% of data reduction in average and more than 40% in maximum. On the other hand, unexpectedly, the worst performance was achieved by Q-Learning, which was a promising candidate at the beginning. This study is helpful for not only wind turbine evaluation particularly the viewpoint of cost, but also understanding nature of wind speed data.

• 한국식품조리과학회지
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• 제22권4호통권94호
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• pp.447-457
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• 2006

In this study, a survey was conducted to analyze the preference and conditions of consumption. A survey of 299 housewives from Seoul and the metropolitan area analyzedthe preference and the conditions of consumption, the general backgrounds and the actual state of diet and health management. According to the survey on the preference of Codonopsis lanceolata, 52.8% answered a traditional market place as the place they most commonly purchased Codonopsis lanceolata. When purchasing Codonopsis lanceolata, 49.2% purchased unwashed. For the frequency of intake, 38.5% of the housewives surveyed answered 1-2 times per year and 38.5% perceived Codonopsis lanceolata a very healthy food. Among the subjects, 46.2% answered their spouse as the person who most likes Codonopsis lanceolata in the family. Regarding the question of why they preferred Codonopsis lanceolata, 39% answered because it was healthy., compared to 36.0% who answered high cost as the reason why they did not prefer Codonopsis lanceolata. Codonopsis lanceolata preference showed a notable difference according to age, average income, interest in health, and intake frequency (p<0.01).

• 한국식품조리과학회지
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• 제18권2호
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• pp.247-261
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• 2002

This study was designed to identify the purchasing practice on the bakery products by the female university students in Seoul and Kyunggi area. Total 262 questionnaires were used for the analysis among 285 responses. The results showed that 50.76% of the respondents bought the bakery products 1∼3 times a month mainly for supper or snacks. The most favored bakery products were bread, danguaja bbang, cake, pie and jori bbang, and there was a signigicant difference in the preference of bakery products by the type of dwelling (p<0.001). Students with non-food science major significantly preferred bakeries as light meals (p＜0.01). Students with food science major liked bread, jori bbang, cake and pie, but the non-food science majors liked bread, sweat red-bean bread and sandwich (p＜0.05). Depending upon the housing status and the major of the respondents, there was a signifcant difference in the purchase factor like nutrition, taste, size and sanitation of the store (p<0.05), while the purchasing frequency was not affected by those factors (p＜0.05). As to the question if there is a room for improvement, different housing status influenced significantly the respondents in citing the factors like business hours and service, and the shape of product and service(p＜0.05).

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.427-432
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• 2001

This paper shows the optimum design of the fluid engine mount. The design has been modified by trial and error because there is many design parameters that can be varied in order to obtain resonant and notch frequencies, and notch depth. It seems to be a great application for optimal design for the mount. Many combinations of parameters are possible to give us the desired resonant and notch frequencies, but the question is which combination provides the lowest resonant peak and notch depth\ulcorner In this study, the enhanced artificial life algorithm is applied to get the desired notch frequency of a fluid mount and minimize transmissibility at the notch frequency. The present hybrid algorithm is the synthesis of an artificial life algorithm with the random tabu (R-tabu) search method. The hybrid algorithm has some advantages, which is not only faster than the conventional artificial life algorithm, but also gives a more accurate solution. In addition, this algorithm can find all global optimum solutions. The results show that the performance of a conventional engine mount can be improved significantly compared with the optimized mount.

• 음성과학
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• 제7권3호
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• pp.263-272
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• 2000

The purpose of this study was to compare receptive language performance and expressive language performance in 13 patients with aphasia by using three stimulus presentation modes: Stimulus mode I (picture), Stimulus mode II (written word), Stimulus m (question using verbal explanation). The stimulus consisted of 10 words. They included 5 functional words and 5 non-functional words. The 13 subjects with aphasia were divided into 2 aphasic types: 5 Broca's aphasics and 8 anomie aphasics. The results were as follows: Firstly, the three stimulus modes didn't affect receptive language performance of aphasia subjects. Secondly; the three stimulus modes were effective on expressive language performance of aphasia subjects. Particularly, stimulus mode II (written words) was effective in naming the aphasia subjects. Thirdly, the functional words with high frequency were better than non-functional words with low frequency on expressive language performance, but not on receptive language performance of aphasia subjects. Finally, the interaction between three stimulus modes and the functional (nonfunctional) words affected expressive language performance only, but not receptive language performance. Particularly, presenting stimulus in written words which are functional words produced the best expressive language performance.

• Corrosion Science and Technology
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• 제3권1호
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• pp.1-5
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• 2004

A polarization resistance is generally used to estimate the corrosion rate in the corrosion monitoring by an electrochemical impedance method. When the Faradaic impedance has a time constant due to the reaction intermediate, the electrochemical impedance describes more than one loop on the complex plane. For example, the electrochemical impedance of iron in acidic solution shows capacitive and inductive loops on the complex plane. In this case, the charge transfer resistance and the polarization resistance are determined at middle and low frequency ranges, respectively. Which should be selected for corrosion resistance in corrosion monitoring, the charge transfer resistance or the polarization resistance'? In the present paper, the above-mentioned question is examined theoretically and experimentally.

• Asia pacific journal of information systems
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• 제1권1호
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• pp.5-16
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• 1991

Business firms have been expressing a strong interest in an effective structure of computing resources. In this respect previous studies provide some guidelines about the deployment of hardware, but the question of which information systems (IS) would be run under the dispersed hardware is still unanswered. The main purpose of the study is to analyze the relationship between various IS characteristics and the distribution of IS. The IS characteristics studied in this research include the usage frequency of IS in a dispersed plant, the currency of information required by the headquarter, the data volume processed in the plant, the relatedness of IS with other information systems in the plant. The survey was performed over the domestic, large manufacturing firms. The most noticeable finding is that the more the updated information is required in the headquarter, or the more related IS is to other information systems in the plant, the more IS is distributed.