• Title/Summary/Keyword: 흐름유도

Search Result 489, Processing Time 0.035 seconds

P2P DRM Algorithm for the protection of contents copyright (콘텐츠 저작권 보호를 위한 P2P DRM 알고리즘)

  • Ha Tae-Jin;Kim Jong-Woo;Han Seung-Jo
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.8 no.8
    • /
    • pp.1783-1789
    • /
    • 2004
  • It is evaluated that there is infinit capability of creating new e business using P2P program. but the research for the method to protect the copyright of digital contents is urgent even for development of the p2p service because the problem of copyright protection for digital contents is not solved. Though this article, it can be induced that reliable contents sharing use to a flow fund by secure settlement architecture, user authentication and contents encryption and then it as the problem of copyright fee is solved, it is able to discontinue which trouble with a creation work for copyright fee and protection it's once again as growth of p2p market, p2p protocal is will be grow into a important protocal of advanced network. In this article, When users send digital contants to each other in internet, we proposed the P2P DRM algorism to offer a security function which using the technology of copyright management to use a AES Algorithm based on PKI.

Deployment of Lean System for Effective Lean Construction Implementation (효과적인 린 건설 수행을 위한 린 시스템 운용 방안 제시)

  • Kim, Dae-Young
    • Korean Journal of Construction Engineering and Management
    • /
    • v.6 no.6 s.28
    • /
    • pp.152-159
    • /
    • 2005
  • Since Lean Construction has been introduced as a new management approach to improve productivity in the construction industry, much research is in progress to develop lean concepts and principles for better implementation and to get results of the successful adaptation of lean ideas from manufacturing for application in the construction industry. Currently, Lean Construction Institute developed Last Planner System to achieve better workflow and effective planning management. Domestic construction companies are also getting interested in the Lean Construction. However, there are no detailed guidelines how to implement lean system. Thus, this study will provide a guideline for deployment of last planner system, a prototype lean implementation control checklist, and all project participants roles based on the case studies in USA. This study should provide a framework to apply lean construction to domestic construction sites.

Efficient Calculation of External Flow for Transient Simulation in Pipe Networks (상수관망의 수격현상 모의를 위한 외부 유출입 유량의 효율적해석)

  • Park, Jae-Hong;Han, Geon-Yeon
    • Journal of Korea Water Resources Association
    • /
    • v.34 no.5
    • /
    • pp.427-438
    • /
    • 2001
  • A numerical model to analyze the unsteady flow in water distribution system was developed by using wave adjustment method. When analyzing the unsteady flow in the real water distribution system, the computational procedures are very complex due to the various boundary condition. Wave adjustment method, which can solve the boundary condition more simply and accurately, was introduced to overcome this difficulty and related equations to solve external flow directly were presented. Using these equations, the numerical model was developed to analyze water hammer. The suggested model was applied to a hypothetical distribution system and a real system with 26 pipes with various external flow boundary condition to evaluate the applicability of the developed model. The simulation results by this model agree with those by Karney's analysis in terms of discharge and pressure.

  • PDF

Analytical Solutions for Predicting Movement Rate of Submerged Mound (수중둔덕의 이동율 예측을 위한 해석해)

    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.10 no.4
    • /
    • pp.165-173
    • /
    • 1998
  • Analytical solutions to predict the movement rate of submerged mound are derived using the convection coefficient and the joint distribution function of wave heights and periods. Assuming that the sediment is moved onshore due to the velocity asymmetry of Stokes' second order nonlinear wave theory, the micro-scale bedload transport equation is applied to the sediment conservation. The nonlinear convection-diffusion equation can then be obtained which governs the migration of submerged mound. The movement rate decreases exponentially with increasing the water depth, but the movement rate tends to increase as the spectral width parameter, $ u$ increases. In comparison of the analytical solution with the measured data, it is found that the analytical solution overestimates the movement rate. However, the agreement between the analytical solution and the measured data is encouraging since this over-estimation may be due to the inaccuracy of input data and the limitation of sediment transport model. In particular, the movement rates with respect to the water depth predicted by the analytical solution are in very good agreement with the estimated result using the discritization technique with the hindcast wave data.

  • PDF

Analysis of the Influence of Ground Effect on the Aerodynamic Performance of a Wing Using Lifting-Line Method (양력선 방법을 이용한 지면효과가 날개의 공력성능에 미치는 영향 분석)

  • Lee, Chang Ho;Kang, Hyung Min;Kim, Cheolwan
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.42 no.4
    • /
    • pp.298-304
    • /
    • 2014
  • The lifting-line method based on Weissinger's method is extended to be able to analyze the ground effect. The method is applied to predict the variation of aerodynamic performance due to ground effect for the elliptic wing with aspect ratio of 10 and the wing of human powered aircraft. While the vortex strength of the wing increases slightly, the downwash decreases significantly as the wing approaches to the ground. For the wing of human powered aircraft, the increment of lift at the height of 2m is 5% than the lift outside the influence of ground effect. The decrease of induced drag at the height of wing span is 10% and at the height of 2m is 55% than that out of ground effect.

Study of Two-shaft Rotary Disc UF Module for the Separation of Oil Emulsion (2축 회전판형 UF 모듈의 Oil Emulsion 분리 특성 연구)

  • 김제우;노수홍
    • Membrane Journal
    • /
    • v.6 no.4
    • /
    • pp.219-226
    • /
    • 1996
  • Rotary disc ultrafiltration module(RDM) was developed for the separation of oil emulsions. This module was devised to reduce the gel polarization phenomenon by alecoupling the operation pressure and the surface velocity of solution in ultrafiltration(UF) processes. Two-shaft engaged disc type RDM having 20 rotary disc membcanes(UOP, USA) was operated under 85kPa vacuum at $25^{\circ}$C. The pressure drop due to slip flow in the two-shaft RDM was found to be proportional to $(2.5{\omega}r)^{2}$. The pure water flux of two-shaft RDM decreased by 9.95% at the angular velocity of 41.89rad/s compared to the decrease of 3.01% for one-shaft RDM at the same velocity. When the angular velocity was changed from 31.42rad/s to 2.62rad/s, the flux decline for 1% cutting oil in two-shaft RDM was 30.16% that is similar to that of one-shaft RDM. Disc gap of 3mm and 7mm did not show any significant differences in the flux for 1% cutting oil solution. A modified model for two-shaft RDM showed good agreement with the experimental results for the cutting oil solution.

  • PDF

Continuous Coprecipitantion Preconcentration-Hydride Generation for Arsenic in Inductively Coupled Plasma-Atomic Emission Spectrometry (연속적 공침 선농축-수소화물 발생법을 이용한 ICP-AES에서의 비소의 감도 개선)

  • Kim, Chang-Gyu;Pak, Yong-Nam
    • Journal of the Korean Chemical Society
    • /
    • v.48 no.6
    • /
    • pp.583-589
    • /
    • 2004
  • In a stream of aqueous sample, trace arsenic ions were quantitatively coprecipitated and detected in ICP-AES through hydride generation. In was used as a coprecipitating reagent. The precipitate was collected on a filter and dissolved by HCl. The eluted As was sent into the reaction coil to generate hydrides and analyzed by ICP. With optimal conditions, and with a sample of 0.3 mL, an enrichment of 70 was obtained with the sampling speed of 10/hr. When compared with coprecipitation and hydride generation technique, the sensitivity was increased by 7 and 10 times, respectively. The limit of detection limit$(3{\sigma})$ was 0.020 ${\mu}g\;L^{-1}$ and the precision was 7-10%. Separation of $As^{3+}\;and\;As^{5+}$ were possible using citric acid in hydride generation.

A study on the manufacturing of motor case assembly for K-PSAM propulsion system by Trans. power molding(TPM) process (유동가압성형(TPM)을 이용한 휴대용 유도무기용 연소관 조립체 제작공정연구)

  • 정상기;윤남균
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.2 no.3
    • /
    • pp.107-115
    • /
    • 1998
  • This paper deals with the study on injection with EPDM(Ethylene propylene dien ter polymer) the gap which narrow, long, and tubular between an ablative composite tube and a steel motor case. Small size motor assembly was designed and manufactured for man-portable air defense propulsion system. Motor assembly is consisted with steel tube, ablative composite tube and insulation rubber. Ablative composite tube was made of carbon/phenolic prepreg by rolling process and insulation rubber was made of EPDM by TPM(Trans-power molding) process. To select the insulation rubber material, we tested ablative insulation property and degradation property at first and we tested fluidity, adhesive property and hardness of EPDM rubber. Finally we designed TPM process to manufacture motor case assembly and the motor case assembly was examined by non-destructive test(X-ray).

  • PDF

Transport of Settling Stones (투하석재의 이동)

  • 유동훈;선우중호
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.11 no.2
    • /
    • pp.107-115
    • /
    • 1999
  • In order to develop a convenient method for the estimation of transport distance of settling stones in quiescent water or flowing water, introduced was the simple but relatively accurate equation of drag coefficient. The equation of drag coefficient introduced was confirmed to give relatively accurate evaluation for the drag force of smooth-surface sphere, and the effects of surface roughness and shape can be considered by adjusting empirical parameters. A theoretical equation has been developed for the settling velocity or settling distance of smooth-surface sphere in quiescent fluid, and the computation results have been obtained by adjusting the empirical parameter for the settling distance of stone in quiescent water. The 2nd order ordinary differential equation has been developed for the case of settling stones in flowing fluid, and a numerical model has been developed by using Runge-Kutta method for its solution. A number of cases have been tested by adjusting the empirical parameter.

  • PDF

Numerical Analysis of Reflection Characteristics of Perforated Breakwater with a Resonant Channel (공진수로 내장형 유공방파제의 반사특성에 관한 수치해석 연구)

  • Kim, Jeong-Seok;Seo, Ji-Hye;Lee, Joong-Woo;Park, Woo-Sun
    • Journal of Navigation and Port Research
    • /
    • v.38 no.5
    • /
    • pp.503-509
    • /
    • 2014
  • In this study, a new concept perforated breakwater is proposed, which is having resonant channels. In the channel, perforated plate is installed for dissipating wave energy induced by flow separations. The breakwater has two advantages compared with conventional perforated breakwater having wave chamber with slotted walls. One is easy to control the target wave condition for dissipating wave energy, and the other is having the high structural safety because the structural members are not exposed to impact waves, directly. To evaluate wave reflection characteristics of the proposed breakwater, numerical experiment was carried out by using Galerkin's finite element model based on the linear potential theory. The results indicated that considerable energy dissipation occurs near the resonant period of channel, and wave reflection characteristics are affected by channel shape, location and opening ratio.