• 한국산학기술학회논문지
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• 제13권1호
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• pp.296-305
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• 2012

본 연구에서는 기존 LED 보안등의 LED 광원 직진성에 의한 눈부심 현상을 개선하고, 조도 균제도를 높게 유지하며, 회전 대칭이 아닌 편축으로 긴 배광 분포를 가지도록 하여 LED 보안등 간에 생기는 광 공핍현상을 해결할 수 있는 보안등용 LED 2차 렌즈를 개발하였다. 개발 광학계는 보안등용 조명 기준에 만족하도록 설계하였으며, 렌즈의 형태는 단일 렌즈로 조명 설계 및 해석 프로그램을 이용한 설계와 분석을 통해 최적화를 하였다. Mock-up을 제작하여 실제 측정을 통해 조도 측정 데이터와 조도 균제도 데이터를 확보하였다.

• 한국전기전자재료학회논문지
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• 제16권11호
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• pp.1041-1046
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• 2003

In order to improve the surface uniformity and the conduction properties of the fabricated YBCO thick films, a system that applies alternating field vertically to the EPD field has been developed for the first time and applied to the electrophoretic deposition process. The applied alternating electric field, so called Shaky Alternating Assisted Field, caused a force to be exerted on each YBCO particle and resulted in a shaking of the particle in the direction of applied electric field, accomplishing a uniform particle orientation. The usual commercial electrical power was used for the vertically applied alternating voltage and the induced electric field was 25-120 V/cm at 60Hz. The thick film fabricated by the method developed in this paper showed better surface uniformity without crack and porosity and improved film characteristics such as critical temperature (Tc,zero = 90 K) and critical current density (2354 A/$\textrm{cm}^2$), Therefore, it is expected that the shaky-aligned electrophoretic deposition method can be used to fabricate superconductor films through a simpler process and at less expense.

• Transactions on Electrical and Electronic Materials
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• 제13권1호
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• pp.16-18
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• 2012

LED lighting systems that combine lighting capability, emotional and physiological characteristics are required for lighting source and multifunctional applications. In this work, Simulation studies using optical analysis software packages, Light Tools, are presented. This is done to estimate the uniformity ratio of illuminance and photosynthetic photon flux density (PPFD) of the periodic 2D lattice arrangements, such as square, diamond, two-way bias quadrangular, hexagonal, and Kagome lattices, under the same transmissivity, absorptance and reflectivity. It has been found out that the two-dimensional Kagome lattice arrangement exhibited high uniformity ratio of illuminance and PPFD compared to other lattices. Accordingly, these results can be used to guide a design and improve the lighting environment which in turn would maximize the uniform distributions of illuminance.

• 반도체디스플레이기술학회지
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• 제19권1호
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• pp.49-54
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• 2020

The voltage drop due to the thin cathode film at the large size top emission OLED panel was successfully compensated with making electrical contact between thin cathode and anode auxiliary electrode by 355nm wavelength of laser. It was found that the luminance uniformity dramatically increased from around 15% to more than 80% through this electrical compensation between thin cathode and anode auxiliary electrode. Moreover, the removing process for EL materials on the anode auxiliary electrode process by laser was very reliable and stable. Therefore, it is thought that the EL removal method using laser to make electrical contacts is very appropriate to mass production for such a large size top emission OLEDs to obtain high uniformity of luminance.

• 조명전기설비학회논문지
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• 제29권12호
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• pp.15-21
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• 2015

We proposed 50W-LED modules of using Heat-pipe and Stack-fin and produced LED modules was evaluated heat dissipation characteristics with comparison of the conventional die-casting type. It verified the application of products by applying it to 150W-LED road luminaires through simulation. The LED module was measures aimed design temperature of the Stack-fin and showed 26% upward heat dissipation effect than a conventional die-casting type. The luminous efficacy of 150W-LED road luminaires using this LED module reached over 112lm/W, and the simulation results showed average of horizontal luminance, overall luminance uniformity($U_O$) and lane luminance uniformity($U_I$) that is suitable for five-lane road with the KS standards.

• 반도체디스플레이기술학회지
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• 제15권4호
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• pp.27-32
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• 2016

In recent years, various researches have been conducted to improve process yields in accordance with miniaturization of semiconductor. APC(Advanced Process Control) is considered one of the methods to increase in process yields. APC is a process control technology that maintains optimal process conditions and improves the reliability of results by controlling and formulating the relationship among the various process parameters and results. We built up an optical diagnostic system with a three-channel spectrometer. The system detects signals those represent the changes of specific emission peaks intensity versus each reference and converts it into MFC control signals to get back the changes to the reference state. Controlling the MFC continues until the specific peak intensity changes into the normal state. Through this device, we tested a APC automatically responding to process changes during the plasma process. We could control gas flow while sputtering process on going and improve uniformity of plasma intensity with this system. Finally, we have got results those enhance the plasma intensity non-uniformity to 7.7% from 15.5%. Also, found unexpected oxygen flow what is estimated to be come out from IGZO target.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.58-58
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• 2009

Uniformity related issues in chemical mechanical polishing (CMP) are within wafer non-uniformity (WIWNU), wafer to wafer non-uniformity (WTWNU), planarity and dishing/erosion. Here, the WIWNU that originates from spatial distribution of independent variables such as temperature, sliding distance, down force and material removal rate (MRR) during CMP, relies to spatial dependency. Among various sources of spatial irregularity, hardness and modulus of pad and surface roughness in sources for pad uniformity are great, especially. So, we investigated the spatial variation of pad surface characteristics using pad measuring system (PMS) and roughness measuring system. Reduced peak height ($R_{pk}$) of roughness parameter shows a strong correlation with the removal rate, and the distribution of relative sliding distance onwafer during polishing has an effect on the variation of $R_{pk}$ and WIWNU. Also, the results of pad wear profile thorough developed pad profiler well coincides with the kinematical simulation of conditioning, and it can contribute for the enhancement of WIWNU in CMP process.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
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• pp.140-143
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• 2008

In this study, it was studied about the improved road light design for drivers and pedestrians using ray- or reverse ray-tracing method. Many of conventional road lights are not suitable for drivers and pedestrians because it has some serious problems such as glare effect or randomicity of illuminated areas. It was oriented from customary design method which was pointed at simple target such as luminance or electrical power. But it was not truth any more that the high luminance or electrical power consumption mean more bright and good mad light. We studied ray-tracing method for road light reflector design to get the several goals. It means that good road light has easy for drivers and Pedestrians eyes and illuminating objects on the road clearly. So, we set the design targets such as uniformity on the road area per one road light, shading angles and continuous luminance uniformity on the long distance road. We designed ideal road light conditions using ray-tracing method. We set the height of drivers and pedestrians eyes and calculated design guideline to make above design targets. Then we designed road light reflector using reverse ray-tracing method. And we achieved same luminance on the road almost half power consumption because we reduced loss of light. We achieved ideal design guide as 75 degrees of shading angles and 0.5 of luminance uniformity on the road area. Finally, we suggested reflector design for 250 watts power consumption CDM light source.

• 한국전자파학회논문지
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• 제16권12호
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• pp.1222-1228
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• 2005

본 논문은 MWO(Microwave Oven)의 동작 주파수로 사용되는 2.45 GHz 대역에서, 전자파 잔향실 내의 전기장특성 향상 및 시험 공간 확장에 관한 연구이다. 잔향실 내부에서의 전자기장 균일성을 확보하기 위하여, Sch-roeder 방식의 Quadratic Residue 확산기(diffuser)를 사용하였고, 전자기장 분포 해석을 위해 FDTD(Finite Difference Time Domain) 수치 해석 방식을 이용하였다. 잔향실 내부의 확산기는 도체로만 설계된 것(Type 1)과 유전체 및 도체를 같이 사용한 것(Type 2, 3)으로 설계하였다. 해석 결과 유전체를 사용한 확산기는, 유전체 없는 확산기의 전기장 특성을 유지하면서 확산기의 물리적 크기를 줄일 수 있었고, 특히 Type 3 확산기에서는 동일한 물리적 공간에 더 많은 주기의 확산기를 설계할 수 있어, 시험 공간 확장, 잔향실의 편파 특성, 편차 및 공차등의 성능이 가장 좋은 것을 확인하였다.

• 대한전자공학회논문지TC
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• 제44권12호
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• pp.79-84
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• 2007

본 논문에서는 CRD(Cubical Residue Diffuser)를 이용하여 전자파 잔향실 내의 전기장 균일도를 향상시키고, 잔향실 내의 전기장 균일도가 최적화되는 CRD 면적비를 연구하였다. $1\sim3$ GHz 주파수 대역에서 Schroeder 방식의 CRD를 설계하였고, 전자파 잔향실 내의 전기장 분포 해석을 위해 FDTD(Finite Difference Time Domain) 수치해석이 이루어졌다. 해석결과 2 GHz에서 CRD의 면적이 잔향실 한쪽 내벽의 약 $40\sim80%$일 경우 전기장 강도 표준 편차가 낮고 균일하게 분포되었으며, 40 % 이하, 또는 80 % 이상의 면적에서는 표준 편차가 높게 나타났다. 특히 가장 나쁜 경우와 비교하여 44%일 때 전기장 균일도가 1 dB 향상됨을 알 수 있었다.