• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.148-154
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• 2008

Diverging channel from gas burner exit to the inlet section of Heat Recovery Steam Generator (HRSG) has been re-designed for 1 MW system. To improve the uniformity in velocity and temperature distribution of existing design(Case A and B) of 300 kW HRSG system, two additional test geometries have been chosen for the numerical simulation. At first, gas burner exit section has been centered to the inlet section of boiler(Case C) and uniformity has been improved considerably. Secondly, the diverging channel length can be further reduced for compact geometry with new guide vane design (Case D and E). Proposed design shows overall improvement in uniformity in velocity and temperature distribution compared to existing one.

• 한국광학회:학술대회논문집
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• 한국광학회 2009년도 창립 20주년기념 특별학술발표회
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• pp.298-299
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• 2009

Use of a DLP-beam projector is proposed to measure solar cell quantum efficiency distribution. The measurement requires a good spatial uniformity of the beam from the projector. We measured the spectral power distribution of the beam projector and the spatial uniformity of the white beam. By changing the gray level of the white beam at the measured spatial points, we improved the spatial illuminance uniformity to be about 2 % which was otherwise as much as 400 %.

• 한국전산유체공학회지
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• 제19권1호
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• pp.73-79
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• 2014

Three-dimensional turbulent flows of a distribution manifold are studied by a turbulence model. To investigate the geometrical effects of the manifold, the length and area of exit port are changed. From the results, flow structures related to the outflow uniformity are examined and the deparure angles are obtained. The exit configuration depending on the departure angle has advantages to the outflow uniformity. That is, the decreased exit area in the streamwise direction improves the uniformity of exit flow. For the uniform effusion, the change of exit port by departure angle is more effective them the change of exit area.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.31-36
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• 2010

SAI(Secondary Air Injection) system has been studied widely as one of the promising countermeasure for reducing HC emission at cold start. In this paper, in order to find out the optimal position of SAI, computational thermal fluid analysis on exhaust system adapted SAI system is performed using commercial 3-D CFD code, CFX. The present results showed that SAI position strongly affected the uniformity of air distribution in front of catalyst. And also through the decision process of optimal position of SAI, new index, uniformity of air distribution($U_{\phi}$) is proposed to define it quantitively. Because $U_{\phi}$ is very simple equation and similar with flow uniformity, it is very easy to figure out the physical meaning and to apply it to practices. Finally, we applied the index $U_{\phi}$ to the decision process of the optimal position of SAI, so that we could get the clear comparison results.

• 한국지반공학회논문집
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• 제21권7호
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• pp.13-20
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• 2005

본 연구에서는 입도분포가 액상화 저항강도 및 동적물성치에 미치는 영향을 실험적으로 검증하였다. 우리나라 준설매립토의 입도분포 조사를 통해 준설매립토의 보편적인 평균입경 4가지와 균등계수 3가지를 선정하였고 평균입경과 균등계수를 각각 달리한 총 12종류의 대표적 준설매립토의 입도분포를 선정, 시료를 제작하였다. 제작된 시료를 이용하여 진동삼축시험을 수행하여 평균입경과 균등계수가 액상화 저항강도에 미치는 영향을 분석하였다. 또한 공진주시험을 수행하여 입도분포가 동적물성치에 미치는 영향도 분석하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.160-160
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• 2008

In practical etching process, etch ant is sprayed on the metal-deposited panel through nozzles collectively connected to the manifold and that panel is usually composed of many PCB(printed circuit board)'s. The etching uniformity, the difference between individual PCB's on the same panel, has become one of most important features of etching process. In this paper, the prediction of nozzle trajectory has been performed by the combination of algebraic formula and numerical simulation. With the pre-determined geometrical factors of nozzle distribution, the trajectories of individual nozzles were predicted with the change of process operational factors such as panel speed, nozzle swing frequency and so on. As results, two dimensional distribution of impulsive force of etchant spray which could be considered as a key factor determining the etching performance have been successfully obtained. Though only qualitative prediction of etching uniformity have been predicted by the process developed in this study, the expansion to the quantitative prediction of etching uniformity is expected to be apparent by this study.

• International Journal of Advanced Culture Technology
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• 제10권3호
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• pp.295-306
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• 2022

The NOx removal performance of the SCR process depends on various factors such as catalytic factors (catalyst composition, shape, space velocity, etc.), temperature and flow rate distribution of the exhaust gas. Among them, the uniformity of the flow flowing into the catalyst bed plays the most important role. In this study, the flow characteristics in the SCR reactor in the design stage were simulated using a three-dimensional numerical analysis technique to confirm the uniformity of the airflow. Due to the limitation of the installation space, the shape of the inlet duct was compared with the two types of inlet duct shape because there were many curved sections of the inlet duct and the duct size margin was not large. The effect of inlet duct shape, guide vane or mixer installation, and venturi shape change on SCR reactor internal flow, airflow uniformity, and space utilization rate of ammonia concentration were studied. It was found that the uniformity of the airflow reaching the catalyst layer was greatly improved when an inlet duct with a shape that could suppress drift was applied and guide vanes were installed in the curved part of the inlet duct to properly distribute the process gas. In addition, the space utilization rate was greatly improved when the duct at the rear of the nozzle was applied as a venturi type rather than a mixer for uniform distribution of ammonia gas.

• 대한인간공학회지
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• 제20권2호
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• pp.59-70
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• 2001

White uniformity is one of the important inspection factors determining the image quality of CRT screen. In the full white pattern, white uniformity means the degree of uniform distribution of white color across the whole screen. To elicit the sensitivity factors affecting the decision of the white uniformity quality, experiments in which participants were confronted with 6 evaluation points embedded in 3 measurement groups on a CRT screen were conducted to gather the psychophysical data that are the level of white uniformity subjects perceived and CA100 produced. These data were used to develop a modified CIE1976 equation for calculating white uniformity. Performance comparison between the original CIE1976 equation and the modified equation was conducted in terms of accuracy test and magnitude estimation. It was concluded the modified equation is more sensitive in the change of white uniformity, compared to the original CIE1976 equation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.73-73
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• 2008

In this work, the study on the $SiO_2$ film non-uniformity by PECVD (Plasma Enhanced Chemical Vapor Deposition) was performed. Plasma diagnostics was analyzed by a DLP(Double Langmuir Probe) and a probe-type QMS(Quadrupole Mass Spectrometer) in order to investigate the spatial distribution of the plasma species in the chamber. The relationship between the plasma species and the depositing rate of the films was examined. On the basis of this work, it was confirmed that O radical density mainly contributed to the increase in the depositing rate of the $SiO_2$ films and the electron temperature in the plasma had a main effect on the formation of the oxygen radicals.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.261-266
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• 2000

Temperature variation during silicon wafer baking is mainly due to natural convection caused by temperature difference between silicon wafer and upper plate. Several cases are tested and calculated numerically to improve temperature uniformity. The temperature difference and velocity magnitude in the flow cell is reduced for a small gap between the wafer and upper plate because the natural convection force is suppressed in the small space. The uniform temperature distribution can be obtained with controling the incoming flow distribution from the upper plate. An alternative method is the adiabatic wall condition on the upper plate to maintain the temperature uniformity within $0.3^{\circ}C$ on the water plate.