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P2P, CDNs, and Hybrid Networks: The Economics of Internet Video Distribution
( Im Sook Ha ),( Steven S. Wildman ),( Johannes M. Bauer ) 정보통신정책학회 2010 정보통신정책연구 Vol.17 No.4
One of the challenges of developing a cost effective distribution system that supports the proliferation of video streams is allocating the video files optimally among various means of media storage. In this paper we develop simple mathematical representations of the cost characteristics of two internet video distribution systems: Content Delivery Networks (CDNs) and Peer-to-Peer (P2P) networks and identify conditions under which each or a blend of the two proves most cost-effective. Our analysis shows that in many cases a hybrid system is likely to have lower costs than either a pure CDN or a pure P2P network. We identify the personal computers that form the backbones of P2P networks as a largely untapped network resource and suggest that potentially very large economic gains might be realized if policy makers can develop policies that effectively address some of the security and transaction cost problems that discourage PC owners from contributing capacity to P2P networks.
P2P, CDNs, and Hybrid Networks: The Economics of Internet Video Distribution
( Im Sook Ha ),( Steven S Wildman ),( Johannes M Bauer ) 정보통신정책학회 2014 정보통신정책연구 Vol.21 No.4
One of the challenges of developing a cost effective distribution system that supports the proliferation of video streams is allocating the video files optimally among various means of media storage. In this paper we develop simple mathematical representations of the cost characteristics of two internet video distribution systems: Content Delivery Networks (CDNs) and Peer-to-Peer (P2P) networks and identify conditions under which each or a blend of the two proves most cost-effective. Our analysis shows that in many cases a hybrid system is likely to have lower costs than either a pure CDN or a pure P2P network. We identify the personal computers that form the backbones of P2P networks as a largely untapped network resource and suggest that potentially very large economic gains might be realized if policy makers can develop policies that effectively address some of the security and transaction cost problems that discourage PC owners from contributing capacity to P2P networks.
LC-MS/MS를 이용한 벌꿀 중 grayanotoxin 분석법 연구 및 실태조사
이숙연(Sook-Yeon Lee),최윤주(Youn-Ju Choi),이강봉(Kang-Bong Lee),조태용(Tae-Yong Cho),김진숙(Jin-Sook Kim),손영욱(Young-Wook Son),박재석(Jae-Seok Park),임성임(Sung-Im Im),최희정(Hee-Jung Choi),이동하(Dong-Ha Lee) 한국식품과학회 2008 한국식품과학회지 Vol.40 No.1
본 연구는 야생꿀을 비롯한 벌꿀, 벌집채꿀 등 국내산 및 수입산 꿀의 안전관리를 위한 grayanotoxin(GTX)의 시험분석법 확립 및 실태조사를 위하여 수행하였다. GTX 표준품 Ⅰ, Ⅱ, Ⅲ는 LC-MS/MS로 분자량을 확인한 후, 시판품인 III를 제외한 Ⅰ과 Ⅱ는 NMR을 이용하여 구조를 확인하였다. 총 111건(국내산 벌꿀 25건, 국내산 야생꿀 21건, 벌집채꿀 13건, 수입산 벌꿀 44건, 수입산 야생꿀 8건)의 벌꿀시료는 메탄올을 사용하여 벌꿀-메탄올 용액을 만들어 tC18 cartridge에 loading 한 후, 여과된 액을 동량의 증류수로 희석하여, 이온화장치로 ESI를 장착한 triplequadrupole LC-MS/MS를 이용하여 분석하였다. LC의 용리액은 1% 포름산이 첨가된 “메탄올-물”을 사용하는 것이 10분 이내의 분석시간대에 나타나는 피크의 모양과 감도가 우수한 경향을 나타내었다. 본 방법을 이용하여 검체 중의 GTX Ⅰ, Ⅱ, Ⅲ의 함유량을 조사한 결과 총 111건 중 수입산 야생꿀 3건(2.7%)에서 GTX Ⅰ, Ⅱ, Ⅲ가 검출되었고, 수입산 야생꿀 1건에서 GTX Ⅰ, Ⅲ가 검출되었다. GTX Ⅰ의 검출량은 최소 3.13 ± 0.00 mg/kg에서 최고 12.93 ± 0.01 mg/kg으로 나타났고 GTX Ⅱ는 0.84 ± 0.01 mg/kg, 0.92 ± 0.00 mg/kg, 1.08 ± 0.01 mg/kg의 함량을 나타내어 GTX Ⅰ에 비해 낮은 수치를 나타내었다. GTX Ⅲ는 최소 0.25 ± 0.01 mg/kg에서 최고 3.29 ± 0.74 mg/kg으로 함량에 큰 차이를 보였다. 본 방법을 이용한 총 111건의 벌꿀 시료의 GTX분석시 수입산 야생꿀 4건에서만 GTX가 검출됨을 알 수 있었다. 본 연구에서는 비휘발성 또는 극성 때문에 GTX 분석시 GC 및 GC-MS에서 분석이 어려운 벌꿀시료를 대상으로 전처리 시간의 단축을 모색함과 동시에 LC-MS/MS를 이용한 시험분석법을 개발할 수 있었고, 모니터링을 통하여 네팔, 터키 등 특정 지역의 야생꿀의 섭취를 제한하는 과학적 근거를 마련할 수 있었다. This study was performed to establish analysis methods, and evaluated for grayanotoxin in domestic/foreign honey and wild honey. The molecular weight of grayanotoxins Ⅰ, Ⅱ and Ⅲ, excluding grayanotoxin Ⅲ that has been commercialized, were analyzed by LC-MS/MS. Then, the molecular structure of grayanotoxins Ⅰ and Ⅱ were analyzed by NMR. A total 111 samples (25 Korean honey, 21 Korean wild honey, 13 Korean honeycomb honey, 44 foreign honey, 8 foreign wild honey) were examined to determined whether or not each sample contained grayanotoxins Ⅰ, Ⅱ, and Ⅲ. The honey samples were mixed with methanol and loaded into a tC18 cartridge, the filtrate was diluted with water, and the mixture was then analyzed by ESI triple-quadrupole LC-MS/MS. Grayanotoxins were only found in the foreign wild honey and were not detected in Korean honey, Korean honeycomb honey, or Korean wild honey. Three of the samples contained grayanotoxin Ⅰ, Ⅱ, and Ⅲ, and one sample contained only grayanotoxins Ⅰ and Ⅲ. The lowest level for grayanotoxin I was 3.13 ± 0.00 mg/kg, and the highest level was 12.93 ± 0.01 mg/kg. The levels of grayanotoxin Ⅱ were 0.84 ± 0.01 mg/kg, 0.92 ± 0.00 mg/kg and 1.08 ± 0.01 mg/kg, respectively. The lowest level of grayanotoxin Ⅲ was 0.25 ± 0.01 mg/kg and the highest level was 3.29 ± 0.74 mg/kg. Through this study, safety management for foreign wild honey has been enabled.
하임숙(Im-Sook Ha),김한국(Han-Gook Kim) 한국엔터테인먼트산업학회 2009 한국엔터테인먼트산업학회논문지 Vol.3 No.2
본 연구는 모바일 VOD, 지상파 DMB, 위성 DMB 로 구성된 국내 모바일 TV시장의 경쟁 관계를 분석한다. 이 세 매체간의 경쟁관계를 분석하기 위해 한정된 자원을 두고 매체들이 경쟁하는 개념인 적소이론 (Niche Theory)을 이용하였다. 매체들의 경쟁상황은 적소 척도인 적소폭(niche breadth), 적소중복(niche overlap), 경쟁적 우위성 (niche superiority) 을 적용한다. 나아가 적소이론을 바탕으로 매체간의 보완, 대체, 배제의 관계를 설명하기 위한 통합 모델을 제안하였다. 분석결과 위성 DMB와 지상파 DMB는 치열한 경쟁관계를 나타냈으며 지상파 DMB의 우월성에 의한 위성 DMB의 대체관계를 도출하였으며 성공적인 국내 모바일 TV의 전략으로 방송기반 DMB와 모바일 VOD의 듀얼모드 비즈니스 전략을 강조하였다. In this study we examine competition between mobile TV services in Korea. To address this question, this study uses niche theory in which media are modeled as competing and coexist on scare resources. The results reveal that the displacement of satellite-based mobile TV (S-DMB) by terrestrial mobile TV (T-DMB) occurs, and T-DMB isa complementarity rather than a complete substitute for streamed mobile TV. Finally we draw business and political lessons for the future design of mobile TV markets based on the experience of South Korea.
골관절염 환자를 위한 타이치, 타이치-자조관리 및 자조관리과정의 효과 비교
조경숙,강현숙,김종임,박원숙,송라윤,안양희,임난영,이인옥,최선하,한상숙,Cho, Kyung-Sook,Kang, Hyun-Sook,Kim, Jong-Im,Bak, Won-Sook,Song, Rha-Yun,Ahn, Yang-Heui,Lim, Nan-Young,Lee, In-Ok,Choi, Sun-Ha,Han, Sang-Sook 대한근관절건강학회 2007 근관절건강학회지 Vol.14 No.1
Purpose: The purpose of the study was to compare the effects of Tai Chi exercise, Tai Chi self help program, and self help management program on arthritic pain, stiffness, fatigue and difficulties in performing daily activities in patients with osteoarthritis. Method: The pre-post experimental design was utilized with convenient sampling at Public Health Centers. Total of 38 subjects agreed to participate in the study with the inclusion criteria of being diagnosed as osteoarthritis and no previous regular exercise. The 12 subjects were assigned to Tai Chi exercise group, 13 subjects to Tai Chi exercise combined with self help management program, and the other 13 to self help management program. Tai Chi exercise group performed exercise twice a week for one hour per each session. Tai Chi self help management group came to the class twice a week, one hour for Tai Chi exercise, and another hour for self help management program. The third group came to the class once a week for one hour to participate self help management program. At the completion of 6 week programs, 10 subjects from Tai Chi exercise, 9 from Tai Chi self help, another 10 from self help management groups completed the post-test measures. The data were analyzed by SPSSWIN 11.0. The homogeneity tests for three experimental groups were conducted by $X^2-test$, Fisher's exact test, Kruskal-Wallis test. The final analysis of the post-test measures was conducted by ANCOVA with fatigue, pain, stiffness, and difficulties in daily activities of the pretest measures as covariates. Results: The results were as follows. There were no significant differences in fatigue, pain, and difficulties of daily activities among three groups for the pretest measures. The score of arthritic stiffness was significantly different among groups after controlled for covariates, but the post-hoc tests showed no group differences. Conclusion: The nursing interventions applied for osteoarthritis patients have been previously tested to show the cost effectiveness of symptoms management of this population.