• Wind and Structures
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• v.7 no.1
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• pp.41-54
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• 2004

An analysis refinement of the Messina Strait suspension bridge project has been recently required, concerning mainly the yaw angle effects on the multi-box deck section aerodynamics and the vortex shedding at low reduced velocities $V^*$. In particular the possible interaction of the axial flow with the large cross beams has been investigated. An original test rig has been designed at this purpose allowing for both forced motion and free motion aero elastic tests, varying the average angle of attack ${\alpha}$ and the deck yaw angle ${\beta}$. The hydraulic driven test rig allowed for both dynamic and stationary tests so that both the stationary coefficients and the flutter derivatives have been evaluated for each yaw angle. Specific free motion tests, taking advantage from the aeroelastic features of the section model, allowed also the study of the vortex shedding induced phenomena.

• Journal of Welding and Joining
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• v.29 no.5
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• pp.58-62
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• 2011

Stainless steels are alloy steels with a nominal chromium content of at least 11 percent, with other alloy additions. The stainlessness and corrosion resistance of these alloy steels are attributed to the presence of a passive oxide film on the surface. When exposed to conditions like Resistance Spot Welding (RSW) process that remove the passive oxide film, stainless steels are subject to corrosive attack. And exposure to elevated temperatures causes oxidation (discoloration) of areas around indentation in Spot welding. In this paper, deal with the effect of shielding gas (Ar) preventing the corrosion, oxidation of stainless steel. And find the optimal shielding gas flow rate. In addition, suggest effective purging method for direct/indirect spot welding process.

• 한국IT서비스학회:학술대회논문집
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• 2009.11a
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• pp.544-548
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• 2009

The underlying success of logistics depends on the flow of data and information for effective management. Over the last 30 years, we have seen the power of microprocessors double about every 18months. This continuing trend means that computers will become considerably smaller, cheaper, and more abundant; indeed, they are becoming ubiquitous and are even finding their way into everyday objects, resulting in the creation of smart things. In the long term, ubiquitous technologies will take on great economic significance. Industrial products will become smart because of their integrated information processing capacity, or take on an electronic identity that can be queried remotely, or be equipped with sensors for detecting their environment, enabling the development of innovative products and totally new services. The global marketplace runs on logistics, security, speed, agility and flexibility..In this paper we report that pairing these traditional logistics functions with RFID technology can be a huge value-driver for companies. This winning combination yields increased logistics management effectiveness and more efficient visibility into the supply chain management.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.301-303
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• 2004

인터넷의 급성장으로 해킹이나 Dos 공격, 웜, 바이러스 등의 사이버 범죄가 크게 증가하고 지능화되어 최근 역추적에 대한 관심이 날로 증가하고 있다. 보안 도구로 침입탐지시스템(IDS) 이나 침입방지시스템 (IPS) 등이 있으나 해킹이나 DoS 공격을 방어하는데 현실적으로 한계가 있다. 따라서 능동적인 해킹 방어를 위한 기본적인 기술로 해커의 실제 위치를 추적하는 역추적 시스템 기술이 필요하다. 특히 IPv4에서의 역추적 시스템에 대한 연구는 활발하게 이루어지고 있지만 IPv6에 대한 연구는 아직 미흡하다. 본 논문에서는 IPv4의 주소 고갈로 인해 앞으로 이를 대신할 IPv6에 대한 공격 근원지 역추적 시스템 개발이 시급하다고 보고. 해킹을 시도하는 해커의 실제 위치를 실시간으로 추적할 수 있도록 IPv6 헤더 패킷의 트래픽 클래스(Traffic Class)와 플로우 라벨(Flow Label)을 이용하여 IPv6에서의 실시간 네트워크 침입자 역추적 시스템 모델을 제안하고자 한다.

• International Journal of Fluid Machinery and Systems
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• v.4 no.1
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• pp.97-103
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• 2011

With the aim to increase blade loadings and stable operating range in highly loaded compressors, this article has been conducted to explore, through a numerical parametric study, the potential of passive control using slotted bladings in cascade configurations. The objective of this numerical investigation is to analyze the influence of location, width and slope of the slots and therefore identify the optimal configuration. The approach is based on two dimensional cascade geometry, low speed regime, steady state and turbulent RANS model. The results show the efficiency of this passive technique to delay separation and enhance aerodynamic performances of the compressor cascade. A maximum of 28.3% reduction in loss coefficient have been reached, the flow turning is increased with approximately $5^0$ and high loading over a wide range of angle of attack have been obtained for the optimized control parameter.

• 전기의세계
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• v.14 no.1
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• pp.35-39
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• 1965

Field problems are solved by a variety of methods. In the relatively small number of cases that are simiple enough, the mathematical attack may be the method of choice. But many field problems with irregular boundary condition must be handled by the use of the electrolitic tank analog, conducting paper or the fluid mapper analog for the purpose of effectiveness and convenience. The method of choice depends on the actual of the problems. There is no one best way to solve all problems. The following points have been described in this apepr, 1. Theoretical studies are made of the vector which is produced by leading the fluid flow vector by a right angle. 2. Curvilinear square method is described., 3. Determination on magnetic flux distribution and variation according to the magnitude of exciting currents.

• 한국전산유체공학회:학술대회논문집
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• 2002.05a
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• pp.88-93
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• 2002

In the present research, a parametric study of aerodynamic characteristics for multi-element airfoils is performed. The major geometric parameters of interest are the gap distance between airfoils and relative deflection angle of slat/flap. The present results are mainly obtained by using inviscid flow calculation, and the aerodynamic characteristics are focused on the surface pressure distribution and the lifts. The results of the present research may be used as not only qualitative data but also quantitative data for small angle of attack flows, where the viscous effect does not play major role in terms of surface pressure distribution and lifts. A further research in this subject including viscous calculation and more geometric parameters is to be performed in the future.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.203-210
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• 2005

Rockey slopes adjacent to railways are disclosed from severe weathering and hazard of failure of themselves. Consequently it causes directly rockfall or landsliding on the railway. Conventional solutions-rigid system like rocksheds, shotcrete, retaining walls, etc to these causes are limited to protect train, rail, our properties and lives from the harmful attack - rockfall. debris flow and sliding. Flexible concept for solutions with passive and active type method based on Euro Code 7 capable of high energy absorption and light materials are rapidly replacing the rigid systems with natural friendly, early installation, cost and time saving and reducing danger in works all over the world.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.627-630
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• 2003

This work presents a numerical procedure to optimize the shape of three-dimensional channel with angled ribs mounted on one of the walls to enhance turbulent heat transfer. The response surface method is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis of flow and heat transfer. SST turbulence model is used as a turbulence closure. The width-to-height ratio of the rib, rib height-to-channel height ratio, pitch-to-rib height ratio and attack angle of the rib are chosen as design variables. The objective function is defined as a linear combination of heat-transfer and friction-loss related terms with weighting factor. D-optimal experimental design method is used to determine the data points. Optimum shapes of the channel have been obtained for the weighting factors in the range from 0.0 to 1.0.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.520-525
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• 2003

A numerical investigation was performed to determine the effect of airfoil on the optimum flap height using NACA0015 Wells turbine. The five double flaps which have 0.5% chord height difference were selected. A Wavier-Stokes code, CFX-TASCflow, was used to calculate the flow field of the Wells turbine. The basic feature of the Wells turbine is that even though the cyclic airflow produces oscillating axial forces on the airfoil blades, the tangential force on the rotor is always in the same direction. Geometry used to define the 3-D numerical grid is based upon that of an experimental test rig. This paper tries to analyze the optimum double flap of Wells turbine with the numerical analysis.