http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
A novel algorithm for scalable <i>k</i>-nearest neighbour graph construction
Park, Youngki,Hwang, Heasoo,Lee, Sang-goo SAGE Publications 2016 JOURNAL OF INFORMATION SCIENCE Vol.42 No.2
<P>Finding the k-nearest neighbours of every node in a dataset is one of the most important data operations with wide application in various areas such as recommendation and information retrieval. However, a major challenge is that the execution time of existing approaches grows rapidly as the number of nodes or dimensions increases. In this paper, we present greedy filtering, an efficient and scalable algorithm for finding an approximate k-nearest neighbour graph. It selects a fixed number of nodes as candidates for every node by filtering out node pairs that do not have any matching dimensions with large values. Greedy filtering achieves consistent approximation accuracy across nodes in linear execution time. We also present a faster version of greedy filtering that uses inverted indices on the node prefixes. Through theoretical analysis, we show that greedy filtering is effective for datasets whose features have Zipfian distribution, a characteristic observed in majority of large datasets. We also conduct extensive comparative experiments against (a) three state-of-the-art algorithms, and (b) three algorithms in related research domains. Our experimental results show that greedy filtering consistently outperforms other algorithms in various types of high-dimensional datasets.</P>
Park, Youngki,Jang, Yong-Seok,Lee, Moon-Ho,Kwon, Oh Woung Korean Society of Forest Science 2007 한국산림과학회지 Vol.96 No.5
Actinidia arguta extracts obtained from three cultivars ('Sae-Han', 'Dae-Sung', and 'Chil-Bo') were assayed for their antioxidant properties and nutritional composition. Antioxidant activity of the extracts was evaluated using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method. Total phenolic contents of the extracts were determined by the Folin-Ciocalteu method. Vitamin C (L-ascorbic acid) content measured by a colorimetric method and reducing sugar content estimated by dinitrosalicylic acid (DNSA) method. Crude extracts from A. arguta 'Sea-Han' showed the most potent radical-scavenging activity showing 86.55% at 10 mg/ml. The DPPH radical scavenging activity of extracts and solvent fractions from Sea-Han cultivar was in decreasing order of EtOAc fraction>BuOH fraction>$CH_2Cl_2$ fraction>hexane fraction, among which EtOAc fraction showed the highest antioxidant activity (87.51 % at 5 mg/ml). Total phenolic contents in A. arguta 'Sae-Han', 'Dae-Sung' and 'Chil-Bo', were 32.93, 28.23, and 25.60 mg/g, respectively. Vitamin C contents of them were 840.57, 578.81 and 730.10 ug/g, respectively.
A Study on a Real Inversion Formula for the Laplace Transformation
Park, Youngki 연세대학교 대학원 1982 延世論叢 Vol.19 No.1
이 논문의 중요한 결과는 다음과 같이 요약된다. (1) 함수 h(s)=h(ξ+iη)는 ζ>0에 대하여 해석적 이고, ξ→0일때 거의 모든 부분에서 Lp(-∞,∞)(1<P≤2) 에 속하는 경계함수를 갖고, ξ>0에 대하여 Cauchy적분 *****(p273) 로 표시된다. h(iη)가 임의의 Lq(-∞,∞) (1<q≤2)에서 Fourieer변환을 가지면, *****(p273) 인 Laplace적분 h(s)= *****로 표시된다. (2) 위의 결과에서 s,t가 real인 경우에 L2(0,∞)에 속하는 φ(t)는 실측을 따라서 h(s)의 값으로 부터 다음과 같이 얻어진다. *****(p273)
Youngki Park,Sea-Hyun Kim,Sun-Ha Choi,Jingyu Han,Hun-Gwan Chung 한국식품과학회 2008 Food Science and Biotechnology Vol.17 No.2
Changes in antioxidant activity of Rubus coreanus fruit of 3 clones (S13, S14, and S16), which were selected from different sites, were studied at different ripening stages. Antioxidant activities (free radical scavenging activity and reducing power) were determined and their relationships to total phenolic contents and ascorbic acid were analyzed. The highest free radical scavenging activities of 3 clones (S13, S14, and S16) were 79.39, 75.80, and 81.16% at 125 μg/mL, respectively. In general, the antioxidant activity and the related parameters, including total phenolic content and vitamin C content decreased during fruit ripening. Total phenolic contents of the R. coreanus fruits (S13, S14, and S16) were correlated with free radical scavenging activity (R<sup>2</sup>=0.8114, 0.9186, and 0.9714). These results improve knowledge of the effect of ripening on the antioxidant activity and related compounds contents that could help to establish the optimum R. coreanus fruit harvest data for various usages.
Breeding of new walnut cultivar, “Golden-ball”
Youngki Park,Chul-Woo Kim,Sea-Hyun Kim,Mahn-Jo Kim,Jae-Hee Kim 한국육종학회 2015 한국육종학회 심포지엄 Vol.2015 No.07
A new cultivar of walnut (Juglans sinensis) was developed through selection from Korea Forest Research Institute. The goals of this research were to evaluate the yielding of walnut and their fruit characteristics of walnut selected from different regions in Korean Wild. Different varieties of walnut grown in Korea, were investigated in what concerns fruit weights, fruit length and their yielding. The walnut belongs to the family Juglandaceae. It is one of the most important nut crops grown in temperate regions. Walnuts, the seeds of J. sinensis are a highly nutritious food. They are also used as a traditional remedy for treating cough, stomach ache and cancer in Asia. The present investigations were undertaken during 2000-2009 in five walnut growing areas. In the present study a wide range of variation was observed in walnut characters from different locations. From these varieties, we have been regularly investigated the fruiting characteristics, which are the average of Fruit Length (FL) and Width (FW), and Weight of Fruit (WF) and Individual Yields (IY), during 10 years to select good quality walnut trees.