• 제목/요약/키워드: Chow

검색결과 315건 처리시간 0.049초

강우시간분포모형의 선정에 따른 홍수유출수문곡선 특성 (Charactristics of Flood Hydrographs by Time Distribution of Rainfall)

  • 노황원;최현일;지홍기
    • 한국수자원학회:학술대회논문집
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    • 한국수자원학회 2009년도 학술발표회 초록집
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    • pp.1546-1550
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    • 2009
  • 최근 증가하고 있는 집중호우로 인해 피해 규모가 대형화 되어가고 있는 추세로 수공구조물 설계시 보다 정확한 수문분석을 요구 하고 있다. 강우의 시간분포는 정확한 수공구조물의 설계시 첨두홍수량 산정에 가장 중요한 영향을 미친다. 따라서 본 연구에서는 지역의 기상학적, 지형학적 특성에 맞는 적절한 강우분포형을 제시하고자 한다. 본 연구는 금호강권역의 단시간 강우에 대한 시간분포형을 결정하기 위하여 기존 강우의 시간분포방법 중에서 개념상 비교적 단순하면서도 물리적으로 의미를 갖는 Mononobe분포, Yen & Chow분포, Keifer & Chu분포의 방법을 이용하였다. 대상지점은 금호강권역의 가창으로 재현기간 50년의 6시간, 24시간 강우의 시간적 분포특성을 비교분석한 결과 6시간 확률강우량에서는 Mononobe 분포와 Keifer & Chu 분포의 첨두치가 비교적 크게 나타났고 24시간 확률강우량에서는 Keifer & Chu 분포의 첨두치가 가장 크게 나타났다. Yen & Chow 분포의 경우 6시간 강우의 첨두치에 비해 24시간 강우의 첨두치가 급격히 감소하는 것을 알 수 있다. 또한 확률강우를 이용해서 홍수유출량을 분석한 결과 6시간, 24시간의 첨두홍수량은 Keifer & Chu 분포가 가장 크게 나오는 것으로 나타났고 첨두시간 역시 Keifer & Chu 분포가 가장 빠른 것으로 나타났다. 최근 다양한 설계강우의 시간분포 방법들이 실제 강우분포의 특성을 표현하고 있지만 이러한 방법들 중에서 실제로 유역에 가장 적합한 시간분포 방법을 결정하기란 어렵다. 하지만, 첨두홍수량 결정을 위해서는 여러 가지 방법들 중 그 지역을 가장 대표할 수 있는 강우분포 방법을 선택해야만 한다. 따라서 분석지점 이외의 다양한 실제 지점에 대해 설계홍수량을 산정해 봄으로써 다른 설계강우의 시간분포 방법을 이용하여 산정한 결과의 비교 검토가 필요할 것으로 사료된다.

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Effects of intermittent ladder-climbing exercise training on mitochondrial biogenesis and endoplasmic reticulum stress of the cardiac muscle in obese middle-aged rats

  • Kim, Kijin;Ahn, Nayoung;Jung, Suryun;Park, Solee
    • The Korean Journal of Physiology and Pharmacology
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    • 제21권6호
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    • pp.633-641
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    • 2017
  • The aim of this study is to investigate the effects of intermittent ladder-climbing exercise training on mitochondrial biogenesis and ER stress of the cardiac muscle in high fat diet-induced obese middle-aged rats. We induced obesity over 6 weeks of period in 40 male Sprague-Dawley rats around 50 weeks old, and were randomly divided into four experimental groups: chow, HFD, exercise+HFD, and exercise+chow. The exercising groups underwent high-intensity intermittent training using a ladder-climbing and weight exercise 3 days/week for a total of 8 weeks. High-fat diet and concurrent exercise resulted in no significant reduction in body weight but caused a significant reduction in visceral fat weight (p<0.05). Expression of $PPAR{\delta}$ increased in the exercise groups and was significantly increased in the high-fat diet+exercise group (p<0.05). Among the ER stress-related proteins, the expression levels of p-PERK and CHOP, related to cardiac muscle damage, were significantly higher in the cardiac muscle of the high-fat diet group (p<0.05), and were significantly reduced by intermittent ladder-climbing exercise training (p<0.05). Specifically, this reduction was greater when the rats underwent exercise after switching back to the chow diet with a reduced caloric intake. Collectively, these results suggest that the combination of intermittent ladder-climbing exercise training and a reduced caloric intake can decrease the levels of ER stress-related proteins that contribute to cardiac muscle damage in obesity and aging. However, additional validation is required to understand the effects of these changes on mitochondrial biogenesis during exercise.

White-Box AES Implementation Revisited

  • Baek, Chung Hun;Cheon, Jung Hee;Hong, Hyunsook
    • Journal of Communications and Networks
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    • 제18권3호
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    • pp.273-287
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    • 2016
  • White-box cryptography presented by Chow et al. is an obfuscation technique for protecting secret keys in software implementations even if an adversary has full access to the implementation of the encryption algorithm and full control over its execution platforms. Despite its practical importance, progress has not been substantial. In fact, it is repeated that as a proposal for a white-box implementation is reported, an attack of lower complexity is soon announced. This is mainly because most cryptanalytic methods target specific implementations, and there is no general attack tool for white-box cryptography. In this paper, we present an analytic toolbox on white-box implementations of the Chow et al.'s style using lookup tables. According to our toolbox, for a substitution-linear transformation cipher on n bits with S-boxes on m bits, the complexity for recovering the $$O\((3n/max(m_Q,m))2^{3max(m_Q,m)}+2min\{(n/m)L^{m+3}2^{2m},\;(n/m)L^32^{3m}+n{\log}L{\cdot}2^{L/2}\}\)$$, where $m_Q$ is the input size of nonlinear encodings,$m_A$ is the minimized block size of linear encodings, and $L=lcm(m_A,m_Q)$. As a result, a white-box implementation in the Chow et al.'s framework has complexity at most $O\(min\{(2^{2m}/m)n^{m+4},\;n{\log}n{\cdot}2^{n/2}\}\)$ which is much less than $2^n$. To overcome this, we introduce an idea that obfuscates two advanced encryption standard (AES)-128 ciphers at once with input/output encoding on 256 bits. To reduce storage, we use a sparse unsplit input encoding. As a result, our white-box AES implementation has up to 110-bit security against our toolbox, close to that of the original cipher. More generally, we may consider a white-box implementation of the t parallel encryption of AES to increase security.

번역자의 책무-발터 벤야민과 문화번역 (The Task of the Translator: Walter Benjamin and Cultural Translation)

  • 윤조원
    • 영어영문학
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    • 제57권2호
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    • pp.217-235
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    • 2011
  • On recognizing the significance of Walter Benjamin's "The Task of a Translator" in recent discourses of postcolonial cultural translation, this essay examines the creative postcolonialist appropriations of Benjamin's theory of translation and their political implications. In an effort to dismantle the imperialist political hierarchy between the West and the non-West, modernity and its "primitive" others, which has been the operative premise of the traditional translation studies and anthropology, newly emergent discourses of cultural translation actively adopts Benjamin's notion of translation that does not prioritize the original text's claim on authenticity. Benjamin theorizes each text-translation as well as the original-as an incomplete representation of the pure language. Eschewing formalistic views propounded by deconstructionist critics like Paul de Man, who tend to regard Benjamin's notion of the untranslatable purely in terms of the failure inherent in the language system per se, such postcolonialist critics as Tejaswini Niranjana, Rey Chow, and Homi Bhabha, each in his/her unique way, recuperate the significatory potential of historicity embedded in Benjamin's text. Their further appropriation of the concept of the "untranslatable" depends on a radically political turn that, instead of focusing on the failure of translation, salvages historical as well as cultural potentiality that lies between disparate cultural entities, signifying differences, or disjunctures, that do not easily render themselves to existing systems of representation. It may therefore be concluded that postcolonial discourses on cultural translation of Niranhana, Chow, and Bhabha, inspired by Benjamin, each translate the latter's theory into highly politicized understandings of translation, and this leads to an extensive rethinking of the act of translation itself to include all forms of cultural exchange and communicative activities between cultures. The disjunctures between these discourses and Benjamin's text, in that sense, enable them to form a sort of theoretical constellation, which aspires to an impossible yet necessary utopian ideal of critical thinking.

중소하천유역에 있어서 유효강우량 및 설계수문곡선의 결정에 관한 연구 - 특히 SCS 방법을 중심으로 - (Determination of Effective Rainfall and Design Hydrograph in Small River Catchment)

  • 김상인;이순택
    • 물과 미래
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    • 제15권3호
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    • pp.49-55
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    • 1982
  • 본 연구는 중소하천유역에 있어서 미국토양보존전국(U.S. Soil conservation Service)의 SCS 방법과 $\Phi$-Index 방법과를 비교하면서 유효우량을 산정하고 또한 설계수문곡선의 첨두유량을 산정하는데 목적을 두고 있다. 낙동강 유역에 속한 신천유역은 UNESCO의 주관아래 국제수문 개발계획 대표시험유역으로 채택되었던 유역으로서 그 중요성이 크다고 생각하여 SCS 방법의 적용을 위하여 균양군의 분류에 따른 토지이용 및 처리 상태와 토양의 분류, 토양의 종류 등을 파악하여 유출수를 구하였다. 그리고 주요호우의 총우량일유효우량관계 자료에 의한 평균유출수와 비교해 본 결과 SCS 방법의 유출수가 적게 나타났으며, 신천유역의 5개 측소의 강우자료로부터 $\Phi$-Index 법에 의한 유효우량과도 비교하였다. 한편 설계수문곡선의 첨두유량은 SCS법, Chow법, Mockus법과 비교해 본 결과, SCS법의 무차원수문곡선과 Chow법이 실측에 의한 단위도의 첨두유량과 가까운 적합성을 보여주었다.

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