• 한국통신학회논문지
• /
• 제37B권9호
• /
• pp.814-821
• /
• 2012

본 논문에서는 하드웨어 기반의 플로우 수락 제어 알고리즘(FAC)을 이용하여 실시간 플로우 관리가 가능한 네트워크 프로세서인 옴니플로우 프로세서를 제안한다. 옴니플로우 프로세서는 플로우 연결 설정 및 해제를 실시간으로 처리하므로 플로우 업데이트 주기를 짧게 설정할 수 있고, 이 주기 내에 입력되지 않는 패킷들이 속하는 플로우의 연결을 해제함으로써 실제 유효한 플로우만을 효율적으로 관리할 수 있다. 그러므로 FAC를 통해 TCP 뿐만 아니라 UDP 응용서비스의 전송 신뢰성을 높힐 수 있다. 이 프로세서는 65nm CMOS 공정에 의해 총 2천5백만 게이트 용량의 칩으로 제작되었으며, 패킷 처리를 위한 32개의 RISC 코어를 이용하여 최대 동작 주파수가 555MHz 일 때 40Gb/s의 처리 성능을 갖는다.

• Journal of Mechanical Science and Technology
• /
• 제16권2호
• /
• pp.165-174
• /
• 2002

In the present study, interfacial cracks between an isotropic and orthotropic material, subjected to static far field tensile loading are analyzed using the technique of photoelasticity. The fracture parameters are extracted from the full-field isochromatic data and the same are compared with that obtained using boundary collocation method. Dynamic photoelasticity combined with high-speed digital photography is employed for capturing the isochromatics in the case of propagating interfacial cracks. The normalized stress intensity factors for static cracks are greate. when ${\alpha}$: 90$^{\circ}$(fibers perpendicular to the interface) than when ${\alpha}$=0$^{\circ}$(fibers parallel to the interface), and those when ${\alpha}$=90$^{\circ}$are similar to ones of isotropic material. The dynamic stress intensity factors for interfacial propagating cracks are greater when ${\alpha}$=0$^{\circ}$ than ${\alpha}$=90$^{\circ}$. For the velocity ranges (0.1 < C/C$\sub$s1/<0.7) observed in this study, the complex dynamic stress intensity factor │K$\sub$D/│increases with crack speed c, however, the rate of increase of │K$\sub$D/│with crack speed is not as drastic as that reported for homogeneous materials.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집B
• /
• pp.341-346
• /
• 2001

The gun-type gas burner adopted in this study is generally composed of some slits and swirl vanes. Therefore, this paper is studied to investigate the effect of slits and swirl vanes on the turbulent flow fields in the horizontal plane of gas swirl burner with a cone type baffle plate measured by using X-probe from hot-wire anemometer system. This experiment is carried out at flow rate $450\;{\ell}/min$, which is equivalent to the combustion air flow rate necessary for heat release 15,000 kcal/hr in gas furnace, in the test section of subsonic wind tunnel. When the burner has only swirl vanes, the axial mean velocity component shows the characteristic that spreads more remarkably toward radial direction than axial one, but when it has only slits, that is developed spreading more toward axial direction than radial one. Therefore, because the biggest speed is spurted in slits and it derive main flow toward axial direction encircling rotational flow that comes out from swirl vane that is situated on the inside of slits, both slits and swirl vanes composing of cone type gas burner act role that decreases the speed near slits and increases the flow speed in the central part of a burner. Moreover, because rotational flow by swirl vanes and fast jet flow by slits increase turbulent intensities effectively coexisting, the turbulent kinetic energy is distributed with a bigger size fairly near slits than burner models which have only slit or swirl vanes within X/R<0.6410.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회B
• /
• pp.3264-3269
• /
• 2007

Combustion instability is a serious obstacle for the lean premixed combustion of gas turbines, and can even cause fatal damage to the combustor and the entire system. Thus, improved understanding of the mechanisms of combustion instability is necessary for designing and operating gas turbine combustors. In this study, in order to understand the instability phenomena, an experimental study was conducted in a rearwardstep dump combustor with LPG and air. The fluctuations of pressure and heat release were measured by piezoelectric pressure sensor and High speed Intensified Charge Coupled Device (ICCD) camera respectively. Various types of combustion modes occurred in accordance with the equivalence ratio and the fuel supplying conditions. The unmixedness of the fuel and air can be controlled by changing the mixing distance ($L_{fuel}$). It is found that the unmixedness of the fuel and air affects the characteristics of flame behavior and pressure fluctuations in a lean premixed flame.

• Tribology and Lubricants
• /
• 제17권5호
• /
• pp.358-364
• /
• 2001

Disk brake system transforms a large amount of kinetic energy to thermal energy in a short time. As the size and speed of automotive increases in recent years, the disk brakes absorbs more thermal energy. And this thermal energy can cause an unacceptable braking performance due to the high transient temperature, that is attained at the friction surface of brake disk and pad. Although these high temperatures are one of the biggest problems. In this study, the overall thermal behavior of ventilated disk brake system was investigated by numerical method. The 3-Dimensional unsteady model was simulated by using a general purpose software package “FLUENT” to obtain the temperature distributions of disk and pad. The model includes the more realistic braking method, which repeats braking and release. The effects of several parameters such as the repeated braking, inlet air velocity and thermal conductivity on the temperature distribution were investigated.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.1342-1347
• /
• 2011

Advantages of the deeply underground subway are underground space efficiency, high speed, decrease of noise and vibration. However, when fire occurs in the deeply underground subway station, large casualties are occurred like Daegu subway station fire due to the increase of evacuation distance. In this study, a numerical analysis was performed by using the fire and evacuation analysis program FDS+EVAC for smoke movement and evacuation in Beotigogae station among the deeply underground subway station. Heat release rate of carriage fire was set 10MW and the fire growth rate was ultrafast. As a result, the smoke move to the exit at 1085 second. The total evacuation time took 956 second.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
• /
• pp.387-389
• /
• 2014

Laminar lifted methane jet flame diluted with nitrogen and helium in co-flow air has been investigated experimentally. This paper examines the role of chemistry, intermediate species responsible for stabilization of lifted flame. To elucidate the stabilization mechanism in lifted methane jet flames with Sc<1, the chemiluminescence intensities of $CH^*$ and $OH^*$ were measured using ICCD camera at various nozzle exit velocities and fuel mole fractions. It has been observed that the $OH^*$ species can play an important role in stabilization of lifted methane jet flame as they are good indicators of heat release rate which can affect on flame speed and increase stability through reduction in ignition delay time.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
• /
• pp.125-128
• /
• 2014

Laminar lifted methane jet flame diluted with nitrogen and helium in co-flow air has been investigated experimentally. This paper examines the role of chemistry, intermediate species responsible for stabilization of lifted flame. To elucidate the stabilization mechanism in lifted methane jet flames with Sc<1, the chemiluminescence intensities of $CH^*$ and $OH^*$ were measured using ICCD camera at various nozzle exit velocities and fuel mole fractions. It has been observed that the $OH^*$ species can play an important role in stabilization of lifted methane jet flame as they are good indicators of heat release rate which can affect on flame speed and increase stability through reduction in ignition delay time.

• 수산해양기술연구
• /
• 제30권4호
• /
• pp.283-291
• /
• 1994

This paper describes about the behavior of the Striped mullet (Mugil cephalus) in the setnet by telemetry techniques. The telemetry system consists of a pinger of 50KHz, three omni-directional hydrophones and ultrasonic receivers, a single board computer for the signal processing, two RF transceivers for the data comunication and a personnel computer. The fish tagged the pinger was tracked by the LBL method, and its location was calculated by the hyperbolic method. The fish escaped from sea surface to 7m deep right after release and had been swum near the sea surface after 30 minutes being released. Also, in horizontal movements, the fish stayed long time around the enterance of the square net in setnet, and showed the escaping behavior repeatly. The average speed of the fish was about 0.41m/sec(1.1 times of the body length)

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.1604-1610
• /
• 2004

A steady dilute premixed combustion at transonic speeds in a diverging channel is investigated. The model explores the nonlinear interactions between the near-sonic speed of the flow, the small changes in geometry from a straight channel, and the small heat release due to the one-step first-order Arrhenius chemical reaction. The reactive flow can be described by a nonhomogeneous transonic small-disturbance (TSD) equation coupled with an ordinary differencial equation for the calculation of the reactant mass fraction in the combustible gas. The asymptotic analysis results in the similarity parameters that govern the reacting flow problem. The model is used to study transonic combustion at various amounts of incoming, reactant mass, reaction rates, and channel geometries.