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A Study on Lightweight Authentication Scheme for Secure CoAP Environment (안전한 CoAP 환경을 위한 경량 인증기법)

  • Woo, Si-Jae;Kim, Dae-Hyun;Kwak, Jin
    • Proceedings of the Korea Information Processing Society Conference
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    • 2017.04a
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    • pp.262-265
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    • 2017
  • IoT 환경에서 사용되는 프로토콜 중 IETF의 CoRE 워킹 그룹에서 채택한 IoT 프로토콜 CoAP가 표준으로 사용되고 있으며 IoT 인증 프로토콜에 대한 연구도 활발하게 이루어지고 있다. CoAP 프로토콜은 저전력, 저용량 메모리 등의 제한된 환경에서 IoT 센서 디바이스들 간의 통신을 지원한다. CoAP 프로토콜은 안전성을 제공하기 위해 DTLS와 함께 사용되는데, 점점 경량화 되어가는 IoT 환경에서 오버헤드가 존재하는 DTLS에 대해 개선되어야 할 사항들이 존재한다. 이를 개선하기 위해 DTLS의 문제점을 해결하기 위한 여러 연구들이 진행되고 있으며, 본 논문에서는 LESS 인증기법을 분석하고 이를 기반으로 보다 향상된 효율성을 제공하는 기법을 제안한다.

A study on the mechanical strength system and supporting method of insulator strings for KEPCO 765kV transmission lines (한전 765 kV 송전선로 애자장치 강도계열 및 지지방식에 관한 검토)

  • Han, Yup;Park, K.H.;Yoon, S.H.;Seo, C.S.
    • Proceedings of the KIEE Conference
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    • 1996.07c
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    • pp.1920-1922
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    • 1996
  • After determining the type and string condition of conductor of 765kV transmission lines, we studied the mechanical strength system of insulator strings to support conductors and insulate conductors from towers. In this paper, for the insulator strings which will be used in 765kV transmission lines, we're going to optimally determine the mechanical strength system and supporting method in the consideration of the reliability, economics and the survey data of T/L routes, and also suggest the calculation method to stipulate for the application limits of suspension and strain insulator strings according to the loadspan and height difference of tower.

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A Study on CoAP Protocol Based on Resource Directory for Hyper Connectivity IoT in Mobile Environments (초연결 사물 네트워크를 위한 모바일 환경에서 자원 디렉토리 기반의 CoAP 프로토콜에 관한 연구)

  • Hang, Lei;Jin, Wenquan;Kim, Do-Hyeun
    • Proceedings of the Korea Information Processing Society Conference
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    • 2015.10a
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    • pp.566-568
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    • 2015
  • 최근 IETF(Internet Engineering Task Force) CoRE(Constrained RESTful Environment) 워킹그룹에서 IoT 프로토콜로 CoAP(Constrained Application Protocol)을 표준으로 채택하였다. 본 논문에서는 모바일 환경에서 CoAP 프로토콜을 이용한 자원 디렉토리 기반의 IoT 노드와 스마트폰 연결 구조를 제시한다. 스마트폰과 IoT(Internet of Things) 노드 사이에 자원 디렉토리를 두고, 이를 통해 스마트폰은 IoT 노드를 검색하고 상황 정보를 습득할 수 있도록 하고 있다.

Separation of Aromatics in Light Cycle Oil by Solvent Extraction - Re-extraction of Aromatics in Extract Phase - (용매 추출법에 의한 분해경유중의 방향족 분리 -추출상중의 방향족의 역수출-)

  • Kim, Su Jin;Kim, Duk-Hyun
    • Applied Chemistry for Engineering
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    • v.8 no.6
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    • pp.967-972
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    • 1997
  • Recovery of aromatics in extract phase which was obtained by batch equilibrium extraction between light cycle oil(LCO) and dimethylsulfoxide(DMSO) solution as solvent was investigated by re-extraction. To select the most suitable re-extraction solvent for recovery of aromatics in extract phase, distribution equilibrium was measured between extract phase and solvents. The solvents used were benzene(B), toluene(T), m-Xylene(mX), n-hexane(Hx) and n-hexane(Hx) and n-Octane(Ot). From the distribution coefficients and yields of aromatics, Hx seemed to be the most suitable. Furthermore, effects of operation parameters for re-extraction of aromatics in the extract phase were studied by batch equilibrium re-extracion with Hx as solvent. Yields of aromatics were found to increase with increasing solvent/feed (extract phase) mass ratio(S/F), while distribution coefficients of aromatics were fixed irrespective of S/F used. Operating temperature did not affect distribution coefficients and yields of aromatics. Distibution coefficients and yields of naphthalene group(carbon numer : 10~12) increased with increasing cabon number. Mass transfer rates of aromatics were also measured with a batch stirred vessel.

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Estimations of the C(t)-Integral in Transient Creep Condition for Pipe with Crack Under Combined Mechanical and Thermal Stress (I) - Elastic-Creep - (복합응력이 작용하는 균열 배관에 대한 천이 크리프 조건에서의 C(t)-적분 예측 (I) - 탄성-크리프 -)

  • Song, Tae-Kwang;Kim, Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.9
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    • pp.949-956
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    • 2009
  • The C(t)-integral describes amplitude of stress and strain rate field near a tip of stationary crack under transient creep condition. Thus the C(t)-integral is a key parameter for the high-temperature crack assessment. Estimation formulae for C(t)-integral of the cracked component operating under mechanical load alone have been provided for decades. However, high temperature structures usually work under combined mechanical and thermal load. And no investigation has provided quantitative estimates for the C(t)-integral under combined mechanical and thermal load. In this study, 3-dimensional finite element analyses were conducted to calculate the C(t)-integral of elastic-creep material under combined mechanical and thermal load. As a result, redistribution time for the crack under combined mechanical and thermal load is re-defined through FE analyses to quantify the C(t)-integral. Estimates of C(t)-integral using this proposed redistribution time agree well with FE analyses results.

Une étude sur les textes théâtrals de Young-Sun Yun: L'écriture théâtrale sur la mort et le deuil (윤영선 희곡 연구: 죽음과 애도의 글쓰기)

  • Ahn, chiwoon
    • Journal of Korean Theatre Studies Association
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    • no.52
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    • pp.117-157
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    • 2014
  • Cette ${\acute{e}}tude$ est pour l'objectif de rechercher sur $l^{\prime}{\acute{e}}criture$ $th{\acute{e}}{\hat{a}}trale$ de la mort et le deuil dans les $th{\acute{e}}{\hat{a}}tres$ chez Young-sun Yun(1954-2007) ${\grave{a}}$ travers des textes dramatiques ${\acute{e}}crits$ par $lui-m{\hat{e}}me$, qui ${\acute{e}}tait$ aussi le metteur en $sc{\grave{e}}ne$ depuis 1994 dans le $th{\acute{e}}{\hat{a}}tre$ contemporain en $Cor{\acute{e}}e$. Cette $th{\grave{e}}se$ est $commenc{\acute{e}}$ ${\grave{a}}$ ${\acute{e}}crire$ pas pour apprendre ses textes mais pour comprendre la ralation entre les textes et les ${\exp}{\acute{e}}riences$ de l'auteur. Ici, pour cela, j''ai $analys{\acute{e}}$ ses 4 $pi{\grave{e}}ces$ $th{\acute{e}}{\hat{a}}trales$ produites ${\grave{a}}$ cette ${\grave{e}}poque$, dont (1994), (2000), $d{\acute{e}}biteur$, mon $p{\grave{e}}re$ est $progress{\acute{e}}$ de cancer>(1996), (2005), en referrant les rapports entre $l^{\prime}{\acute{e}}criture$ dramatique et de la mort et le deuil de $p{\grave{e}}re$. Cette ${\acute{e}}tude$ $pr{\acute{e}}suppose$ un certain situation psychologue de l'auteur sur la mort et le deuil de personnage '$p{\grave{e}}re$'. L'auteur dramatique et le metteur en $sc{\grave{e}}ne$ du $th{\acute{e}}{\hat{a}}tre$ Young-sun Yun propose certaines orientations de la mort de son $p{\grave{e}}re$ dans ses texts dramatiques: le sentiment de victime sous le pouvoir absolu de son $p{\grave{e}}re$. Chez lui, ${\acute{e}}crire$ le texte dramatique, c'est transmettre les amertumes d'esprit et une forme de $r{\acute{e}}flextion$ vis-${\grave{a}}$-vis de la relation avec son $p{\grave{e}}re$ surtout le $probl{\grave{e}}me$ $inachev{\acute{e}}$ de deuil. c'est-${\grave{a}}$-dire fournir des sentiments coupables et des $anxi{\acute{e}}t{\acute{e}}s$ qui $r{\acute{e}}sident$ au fond de son coeur, tout au long de sa vie. Pour cette objecif, il est ${\acute{e}}vident$ qu'il faudra toujours partir du texte et y revenir. J'ai $essay{\acute{e}}$ de ne pas $r{\acute{e}}duiser$ $l^{\prime}{\acute{e}}tude$ des textes au respect myope des paroles des personnage et rester la $r{\acute{e}}flextion$ pshchologique sur la mort et le processu de deuil. J'ai $essay{\acute{e}}$ d'appuyer mes remarques sur les sources $autoris{\acute{e}}es$: psychanalytiques en la $mati{\grave{e}}re$. C'est pourquoi j'ai cru devoir $pr{\acute{e}}senter$ cette recherche de l'analyse sous la forme d'une $synth{\grave{e}}se$ des principaux concepts de la $th{\acute{e}}orie$ de la pshchologie moderne qui permettent l'analyse des textes dramatiques.(Dany Nobus, David K. Switzer, Fritz Riemann, Giles Deleuze, Sigmund Freud, Julia Kristeva) Et auiss j'ai $essay{\acute{e}}$ de explorer l'imaginaire des paroles dans les textes en ses rapports avec l'auteur et les personnages et entre les personnages. Ainsi conçu, j'ai $analys{\acute{e}}$ les formes de paroles en ce qui concerne la mort de $p{\grave{e}}re$ et le deuil. Cette $mani{\grave{e}}re$ s'est $r{\acute{e}}v{\acute{e}}l{\acute{e}}e$ efficace pour montrer comment des traces de sentiment se transforment dans des textes. Dans les pluparts des personnages chez les textes de Young-sun Yun, on peut voir si $d{\acute{e}}finitivement$ leur cicatrices personnelles, $sensibilit{\acute{e}}s$ $m{\hat{e}}l{\acute{e}}s$, ce 'je-ne-pourrai-rien-contre-mon-$p{\grave{e}}re$' ou 'je-ne-sais-quoi-et-presque-$apr{\grave{e}}s$-la mort-de-mon pere'. Pour $d{\acute{e}}pouiller$ cet aspect, j'ai $montr{\acute{e}}$ qu'il n'y avait pas de $v{\acute{e}}rit{\acute{e}}s$ objectives, mais que la $subjectivit{\acute{e}}$ doit trouver le jeu triangulaire entre l'inconscient de l'auteur par les paroles des textes et par les rapports entre le symbolisant et le $symbolis{\acute{e}}$ dans les $repr{\acute{e}}sentation$ socio-culturelle en $Cor{\acute{e}}e$ d'aujourd'hui.

Numerical Analysis of NACA64-418 Airfoil with Blunt Trailing Edge

  • Yoo, Hong-Seok;Lee, Jang-Chang
    • International Journal of Aeronautical and Space Sciences
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    • v.16 no.4
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    • pp.493-499
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    • 2015
  • The aerodynamic performance of blunt trailing edge airfoils was investigated. The flow fields around the modified NACA64-418, which consists of the tip blade of the wind turbine and Mexico model of IEA wind, were analyzed. To imitate the repaired airfoil, the original NACA64-418 airfoil, a cambered airfoil, is modified by the adding thickness method, which is accomplished by adding the thickness symmetrically to both sides of the camber line. The thickness ratio of the blunt trailing edge of the modified airfoil, $t_{TE}/t_{max}$, is newly defined to analyze the effects of the blunt trailing edge. The shape functions describing the upper and lower surfaces of the modified NACA64-418 with blunt trailing edge are obtained from the curve fitting of the least square method. To verify the accuracy of the present numerical analysis, the results are first compared with the experimental data of NACA64-418 with high Reynolds number, $Re=6{\times}10^6$, measured in the Langley low-turbulence pressure tunnel. Then, the aerodynamic performance of the modified NACA64-418 is analyzed. The numerical results show that the drag increases, but the lift increases insignificantly, as the trailing edge of the airfoil is thickened. Re-circulation bubbles also develop and increase gradually in size as the thickness ratio of the trailing edge is increased. These re-circulations result in an increase in the drag of the airfoil. The pressure distributions around the modified NACA64-418 are similar, regardless of the thickness ratio of the blunt trailing edge.

Anti-Obese Effects of Ginseng/Ginsenosides : A Literature Review from 1983 to 2012 (인삼과 진세노사이드의 항비만 효과에 대한 문헌 고찰)

  • Choi, Munji;An, Jinpyo;Kim, Ae Jung;Lee, Myoungsook
    • Journal of the East Asian Society of Dietary Life
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    • v.24 no.3
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    • pp.335-350
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    • 2014
  • Compared to the large numbers of studies on the diabetes, hyperlipidemia and cancer therpeutic effects of ginseng, the anti-obese effect and mechanisms of ginsengs have not been studied as much. To determine the effects of ginseng on obesity, 14 keywords (ginseng, ginsenoside, obesity, weight, fat, diet, overeat, appetite, lipid, 3T3-L1, adipocyte, food intake, adipogenesis and lipolysis) were combined in searching a database. Fifty-six articles published from 1983 to 2012 as well as 656 patents registered until Aug $17^{th}$, 2012, were screened for anti-obese effects of ginseng. In the classification of experimental methods, 16 papers on 3T3-L1 cells, 38 papers on animals and three papers on human were reviewed. In terms of obese mechanisms of action, the most commonly used biomarkers were in order of lipid profiles > weight change > blood glucose > adipocytokine. Most ginseng studies on obesity focused on AMPK, $PPAR{\gamma}$, GLUT-4, PI3K and SREBP-1. Korean white ginseng extracts and Re repressed the lipogenesis genes such as PPARc2, SREBP-1c, LPL, FAS and DGAT1. However, ginseng or ginsenosides, PD (Rb1) and PT (Re), showed different or contradictory results. Water and ethanol extraction of ginseng showed contradictory effects on the secretion of inflammatory cytokines, wheras IL-6 was repressed by ethanol extracts and TNF-${\alpha}$ repressed by Re in vitro. Based on the literature, further studies on anti-obese mechanisms of ginseng, such as the inflammation-related obesity or cross signals between the adipocytes and the environments, are needed, instead of more studies on its hypolipidemic and hypoglycemic effects.