• 한국도서관정보학회지
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• 제44권1호
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• pp.27-47
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• 2013

이 연구에서는 자동 색인을 통해 쉽게 얻을 수 있는 자질의 문헌빈도와 장서빈도를 이용하여 자동분류에서 자질 선정 기법을 kNN 분류기에 적용하였을 때, 어떠한 분류성능을 보이는지 알아보고자 하였다. 실험집단으로 한국일보-20000(HKIB-20000)의 일부를 이용하였다. 실험 결과 첫째, 장서빈도를 이용하여 고빈도 자질을 선정하고 저빈도 자질을 제거한 자질선정 방법이 문헌빈도보다 더 좋은 성능을 가져오는 것으로 나타났다. 둘째, 문헌빈도와 장서빈도 모두 저빈도 자질을 우선으로 선정하는 방법은 좋은 분류성능을 가져오지 못했다. 셋째, 장서빈도와 같은 단순빈도에서 자질 선정 구간을 조정하는 것이 문헌빈도와 장서빈도의 조합보다 더 좋은 성능을 가져오는 것으로 나타났다.

• BMB Reports
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• 제51권1호
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• pp.1-2
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• 2018

Positive selection on a new beneficial mutation generates a characteristic pattern of DNA sequence polymorphism when it reaches an intermediate allele frequency. On genome sequences of African Drosophila melanogaster, we detected such signatures of selection at 37 candidate loci and identified "sweeping haplotypes (SHs)" that are increasing or have increased rapidly in frequency due to hitchhiking. Based on geographic distribution of SH frequencies, we could infer whether selective sweeps occurred starting from de novo beneficial mutants under simple constant selective pressure. Single SHs were identified at more than half of loci. However, at many other loci, we observed multiple independent SHs, implying soft selective sweeps due to a high beneficial mutation rate or parallel evolution across space. Interestingly, SH frequencies were intermediate across multiple populations at about a quarter of the loci despite relatively low migration rates inferred between African populations. This invokes a certain form of frequency-dependent selection such as heterozygote advantage. At one locus, we observed a complex pattern of multiple independent that was compatible with recurrent frequency-dependent positive selection on new variants. In conclusion, genomic patterns of positive selection are very diverse, with equal contributions of hard and soft sweeps and a surprisingly large proportion of frequency-dependent selection in D. melanogaster populations.

• Korean Journal of Mathematics
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• 제32권2호
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• pp.213-218
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• 2024

Assume that at a certain locus there are three genotypes and that for every one progeny produced by an I^AI^A homozygote, the heterozygote I^AI^B produces. W. Choi found the adapted partial differential equations for the density and operator of the frequency for one gene and applied this adapted partial differential equations to several diploid model. Also, he found adapted partial differential equations for the diploid model against recessive homozygotes and in case that the alley frequency occurs after one generation of selection when there is no dominance. (see. [1, 2]). In this paper, we find the adapted partial equations for the model of selection against heterozygotes and in case that the allele frequency changes after one generation of selection when there is overdominance. Finally, we shall find the partial differential equation of general type of selection at diploid model and it also shall apply to actual examples. This is a very meaningful result in that it can be applied in any model.

• 전자공학회논문지
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• 제52권7호
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• pp.165-168
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• 2015

본 논문에서는 파일럿 심볼을 이용한 안테나 선택방법을 적용한 SFBC-OFDM(Space Frequency Block Code-Orthogonal Frequency Division Multiplexing) 시스템에 대한 성능을 분석한다. 안테나 선택은 파일럿 심볼로부터 산출된 채널 계수에 기반하여 결정된다. 각 주파수에서, 산출된 채널 계수들을 정렬하고 그 중 가장 양호한 채널이 선택된 후 가장 좋은 계수를 가지는 안테나로 데이터가 전달된다. 또한 이 방법에 대해서 부호 이득과 다이버시티 이득도 분석된다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권5호
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• pp.682-686
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• 2016

A fully differential RC calibrator for accurate cut-off frequency of a programmable channel selection filter is proposed. The proposed RC calibrator consists of an RC timer, clock generator, synchronous counter, digital comparator, and control block. To verify the proposed RC calibrator, a six-order Chebyshev programmable low-pass filter with adjustable 3 dB cut-off frequency, which is controlled by the proposed RC calibrator, was implemented in a $0.18-{\mu}m$ CMOS technology. The channel selection filter with the proposed RC calibrator draws 1.8 mA from a 1.8 V supply voltage and the measured 3 dB cut-off frequencies of the channel selection LPF is controlled accurately by the RC calibrator.

• 한국의상디자인학회지
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• 제17권3호
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• pp.99-113
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• 2015

The purpose of the study was to explore differences in perceived importance among factors of motives for participating in outdoor sports, product selection criteria of outdoor sportswear and store selection criteria, and in buying frequencies among store types and store locations. Another purpose was to find differences in importance of product selection criteria of outdoor sportswear and store selection criteria and in buying frequencies according to store types and store locations among groups according to motives for participation in outdoor sports. The questionnaire was developed by the researcher and was collected by 221 women aged between 40 and 59. The questionnaire was composed of four parts including participation motives, store selection criteria, and product selection criteria measured by Likert type scale, and demographic characteristics measured by nominal scale. Data were analyzed by frequency test, factor analysis, repeated measure ANOVA, Bonferroni adjusted t-test, cluster analysis by Ward method, ANOVA and Tukey's test as a post-hoc test. The results of the study showed that middle-aged women rated health improvement motive as the most important factor for participating in outdoor sports. Among product selection criteria, comfort was the most important, and among store selection, personal selling was the most important. Among store types, buying frequency in off-price store was the highest and among store locations, buying frequency in stores in a residential area was the highest. Moreover, three groups were classified according to motives for participation in outdoor sports: the health improvement motive group, the conspicuous/sociable motive group, the lower motive group The health improvement motive group rated comfort as the most important factor for product selection criteria, and showed the highest buying frequency in downtown stores. Conspicuous/sociable motive groups valued design and utilization for an everyday wear and shopped more frequently in specialty store and/or in downtown stores.

• 지구물리와물리탐사
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• 제7권1호
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• pp.19-24
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• 2004

Frequency-space domain full-wave tomography is a promising technique for delineating detailed subsurface structure with high resolution. However, this method requires criteria for the selection of a set of optimal temporal frequency components, to achieve stability in the sequence of inversion processes together with computational efficiency. We propose a method of selecting optimal temporal frequencies, based on wavenumber continuity. The proposed method is tested numerically and is shown to be able to select an optimal set of frequency components that are sufficient to image the anomalies.

• 지구물리와물리탐사
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• 제14권3호
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• pp.214-219
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• 2011

본 논문에서는 시간영역에서 분리된 잔여 파동장을 이용하여 주파수영역 파형역산을 수행하였다. 시간영역 잔여 파동장들을 절대값의 크기에 따라 정렬하여 분류하고, 이를 여러 개의 그룹으로 분리하였다. 분리된 잔여 파동장들은 각 그룹별로 목적함수의 경사 방향을 정규화한 후 평균하기 때문에 통상적인 잔여 파동장에서 작은 크기를 가지는 파동장들을 상대적으로 강조하는 효과가 있고, 이는 파형역산 시 심부구조의 이미지 향상에 도움을 준다. 파형역산은 시간영역에서 분리된 잔여 파동장을 이용하여 주파수영역에서 수행되며, 목적함수의 경사방향은 구조보정에서 많이 쓰이는 역전파 기법을 적용하여 계산된다. 본 연구에서 제안한 알고리듬의 타당성을 확인하기 위하여 SEG/EAGE 암염 모델과 Marmousi 모델을 이용하여 파형역산을 수행하였다. 역산 결과를 통해 제안된 알고리즘이 일반적인 주파수영역 파형역산에 비해 심부구조에 대하여 향상된 결과를 제시함을 확인하였다.

• Interdisciplinary Bio Central
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• 제6권1호
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• pp.1.1-1.6
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• 2014

A growing body of evidence shows that most psychological traits are polygenic, that is they involve the action of many genes with small effects. However, the study of selection has disproportionately been on one or a few genes and their associated sweep signals (rapid and large changes in frequency). If our goal is to study the evolution of psychological variables, such as intelligence, we need a model that explains the evolution of phenotypes governed by many common genetic variants. This study illustrates simple statistical tools to detect signals of recent polygenic selection: a) ANOVA can be used to reveal significant deviation from random distribution of allele frequencies across racial groups. b) Principal component analysis can be used as a tool for finding a factor that represents the strength of recent selection on a phenotype and the underlying genetic variation. c) Method of correlated vectors: the correlation between genetic frequencies and the average phenotypes of different populations is computed; then, the resulting correlation coefficients are correlated with the corresponding alleles' genome-wide significance. This provides a measure of how selection acted on genes with higher signal to noise ratio. Another related test is that alleles with large frequency differences between populations should have a higher genome-wide significance value than alleles with small frequency differences. This paper fruitfully employs these tools and shows that common genetic variants exhibit subtle frequency shifts and that these shifts predict phenotypic differences across populations.

• 한국식생활문화학회지
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• 제30권5호
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• pp.611-620
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• 2015

This study was conducted on wine consumers to explore their behavioral characteristics concerning their drinking frequency of wine, wine selection factors, and difficulties in selecting wines. Data were collected during February 19th 2014 to April 20th 2014. Respondents were students who were taking classes about wine at a University located in the Gyeonggi-do area. Prior to the analysis, wine consumers were classified based on frequency of consumption: those who consumed wine less than once a month were classified as "Tell me consumers", whereas those who consumed wine once or more a month were classified as "Engage me consumers." The wine selection factors of the two groups were as follows: 'label aspect', 'taste and aroma', 'use purpose', and 'price and recommendation'. Regarding 'label aspect' and 'use purpose', there were significant differences between the two groups. Regarding difficulties in selecting wines, "Tell me consumers" mentioned the following: 'experience', 'price', and 'food pairing'. "Engage me consumers" mentioned the following: 'ability to identify new wines' and 'tastes of others who drink with or oneself'. Classifying domestic wine consumers and their behavioral features of drinking frequency of wine can be used for market segmentation of wine consumers.