• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 추계학술대회 논문집
• /
• pp.525-528
• /
• 2001

ZnO:Al thin film can be used as a transparent conducting oxide(TCO) which has low electric resistivity and high optical transmittance for the front electrode of amorphous silicon solar cells and display devices. This study of electrical, crystallographic and optical properties of Al doped ZnO thin films prepared by Facing Targets Sputtering (FTS), where strong internal magnets were contained in target holders to confine the plasma between the targets, is described. Optimal transmittance and resistivity was obtained by controlling flow rate of O$_2$ gas and substrate temperature. When the of gas rate of 0.3 and substrate temperature 200$^{\circ}C$ , ZnO:Al thin film had strongly oriented c-axis and lower resistivity(<10$\^$-4/Ω-cm).

• 한국정보과학회:학술대회논문집
• /
• 한국정보과학회 2006년도 한국컴퓨터종합학술대회 논문집 Vol.33 No.1 (B)
• /
• pp.394-396
• /
• 2006

A blooming area of processor design is represented by scalable computing fabric. As the structure of the processors developed using seal-able computing fabric evolved from simple programmable units to processors supporting change of flow instructions and function calls, an increasing interest is in developing the compiling technology that will allow us to harness not only the full power of their hardware but also to target multiple architectures. In this paper we present the front-end of a generic compiler, able to accept a various source languages and transform them in a common intermediate representation.

• 한국환경복원기술학회지
• /
• 제5권5호
• /
• pp.11-21
• /
• 2002

A series of model tests is performed to evaluate the relationship between soil and a buried pipe in soil undergoing lateral movement. As the result of the model tests, a wedge zone and plastic flow zones could be observed in front of the pipe. And also an arc failure of cylindrical cavity could be observed at both upper and lower zones. Failure shapes in both cohesionless and cohesive soils are nearly same, which was investigated failure angle of $45^{\circ}+{\phi}/2$. In the cohesionless soil, the higher relative density produces the larger arc of cylindrical cavity. On the basis of failure mode observed from model tests, the lateral earth pressure acting on a buried pipe in soil undergoing lateral movement could be applying the cylindrical cavity extension mode. The deformation behavior of soils was typically appeared in three divisions, which are elastic zones, plastic zones and pressure behavior zones.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 추계학술대회논문집
• /
• pp.106-112
• /
• 2000

Axial fans are widely used in heavy machines due to their ability to produce high flow rate for cooling of engines. At the same time. the noise generated by these fans causes one of the most serious problems. This work is concerned with the low noise technique of discrete frequency noise. The prediction model. which allowed the calculation of acoustic pressure at the blade passing frequency and it's harmonics. has been developed by Farrasat. This theory is founded upon the acoustic radiation of unsteady forces acting on blade. To calculate the unsteady resultant force over the fan blade. Time-Marching Free-Wake Method are used. The fan noise of fan system having unsymmetric engine-room is predicted. In this paper, the discussion is confined to the performance and discrete noise of axial fan and front part of engine room in heavy equipments.

• 한국산학기술학회:학술대회논문집
• /
• 한국산학기술학회 2001년도 추계산학기술 심포지엄 및 학술대회 발표논문집
• /
• pp.144-146
• /
• 2001

본 연구는 사출성형공정상에서 발생할 수 있는 문제점을 설계시에 미리 예측하여 좋은 설계를 얻기 위한 시도이다. 사출성형 관련 설계는 사출금형설계전문가의 축적된 지식과 경험을 활용하여 수행되어 왔으며, 설계에 필요한 설계자의 경험이 전무한 경우 많은 시행오치를 유발하고 있는 실정이다. 본 연구에서는 백라이트 패널을 설계함에 있어 설계초기에 성형시 발생할 수 있는 성형성, 기계적 강도 등의 문제를 수치해석을 통하여 시뮬레이션 함으로써 시행오차를 최소화하고 성형성을 고려한 설계를 구현하고자 시도하였다.

• 설비공학논문집
• /
• 제12권3호
• /
• pp.277-283
• /
• 2000

The heat transfer characteristics for air jet vertically impinging on a flat plate which had a set of hybrid rod were investigated experimentally. The rod had a cross section made with a half of circular cross section and that of rectangular and was installed in front of the plate. The heating surface was given constant heat flux value of 1020 W/$m^2^{\circ]C$ and the problem parameters investigated were jet Reynolds number, nozzle-to-plate spacing and the rod size. The local and local average Nusselt number characteristics were found to be dependent on the rod size because the flow was disturbed by installing the rod. Higher convective heat transfer rate occurred in the whole plate as well as in the stagnation region.

• Wind and Structures
• /
• 제29권1호
• /
• pp.55-64
• /
• 2019

The effect of vortex impingement on the fluid dynamics around a cylinder submerged in the wake of another of different diameters is numerically investigated at a Reynolds number Re = 200. While the diameter (D) of the downstream cylinder is fixed, impinging vortices are produced from the upstream cylinder diameter (d) varied as d/D = 0.24, 0.4, 0.6, 0.8 and 1.0, with a spacing ratio L=5.5d, where L is the distance between the center of the upstream cylinder to the front stagnation point of the downstream cylinder. Two-dimensional simulations are carried out using the finite volume method. Fluid forces acting on the two cylinders are correlated with impinging vortices, vortex shedding, and wake structure. Different facets of wake formation, wake structure, and flow separation and their connections to fluid forces are discussed.

• 한국항만학회지
• /
• 제10권1호
• /
• pp.53-61
• /
• 1996

This paper describes the effect of wave control using submerged flat plate by the numerical calculation and the hydraulic model test. The boundary element method is used to develop a numerical solution for the flow field caused by monochromatic oblique waves incident upon an infinitely long, sumerged flat plate situated in arbitrary water depth. The effect of wave blocking is examined according to the change of length, submerged depth of flat plate and incident angles. Numerical results show that longer length, shallower submergence of flat plate and larger incident angles enhance the effect of wave blocking. To validate numerical analysis method, hydraulic model test was conducted in 2-D wave flume with 60 cm metal sheet. Reflected waves are extracted from water surface elevation in front of the location of a submerged plate by least square method with 3 wave gages. From comparing experimental results with numerical results, efficiency of numerical analysis method by this study could be confirmed well within wide ranges of wave frequencies.

• 천문학회보
• /
• 제45권1호
• /
• pp.32.1-32.1
• /
• 2020

An independent determination of H0 is crucial given the growing tension of the Hubble constant (H0). In this work, we present a new determination of H0 using velocities and Tip of the Red Giant Branch (TRGB) distances to 33 galaxies in front of the Virgo Cluster. We model the infall pattern of the local Hubble flow modified by the Virgo mass, as a function of the H0, the radius of the zero-velocity surface R0, and the intrinsic velocity scatter. Fitting velocities and TRGB distances of 33 galaxies to the model, we obtain H0 = 65.6 +/- 3.4 (stat) +/- 1.0 (sys) km/s/Mpc and R0 = 6.96 +/- 0.35 Mpc. Our local H0 is consistent with the global H0 determined from cosmic microwave background radiation, showing no tension.

• 한국추진공학회지
• /
• 제2권2호
• /
• pp.64-73
• /
• 1998

항공기용 엔진에는 압축기단들 사이에 스트럿을 포함하는 S자형 환형덕트가 존재하기도 한다. 이러한 엔진에서 S자형 덕트를 통과하는 유동은 볼록면과 오목면을 따라 가면서 가속과 감속이 이루어지고, 벽면에서의 경계층 성장으로 인해 유로폐쇄량이 증가한다. 이처럼 S자형 덕트의 영향으로 후방에 존재하는 압축기는 불균일한 축방향 속도분포에 따른 영향을 받게 된다. 따라서, 후방 압축기는 전방에 위치한 S자형 덕트의 영향을 충분히 고려하여 설계하여야 한다. S자형 덕트가 미치는 영향을 고려하여 설계된 원심압축기의 성능을 검증하고, S자형 덕트가 원심압축기 성능에 미치는 영향을 파악해보기 위해 압축기 입구에 S자형 환형덕트를 장착한 경우와 원통형 덕트를 장착한 경우에 대해 각각 성능시험을 수행하였다. 시험결과를 통해 입구에 S자형 덕트가 있는 경우에는 없는 경우보다 압축비 및 효율 등 압축기 성능이 저하되고, 쵸킹유량이 감소함을 알 수 있었다. 이러한 성능저하의 원인을 분석하기 위해 S자형 덕트를 포함하는 임펠러의 유동해석을 수행하였으며, 그 결과 성능저하의 원인은, S자형 덕트와 임펠러의 상호작용으로 설계시 예측했던 것보다 인듀서팁에서 상대마하수가 증가하였고, 영각이 감소하였기 때문임을 확인할 수 있었다.