• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.140-147
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• 2011

In this paper, we propose a novel feeding method that uses a windshield ground in a vehicle. The feeding method enables for various antennas to integrate easily in a vehicle windshield. To connect a coaxial feeding cable directly to the windshield ground, we inserted a coaxial-to-ground adapter between the cable and the ground, and reflection coefficients using the proposed feeding method were compared to that using a conventional feeding method. The size and position of the windshield ground were optimized in order to achieve a high radiation gain in the azimuth direction. Then the triangular WiBro patch antenna, incorporating the proposed feeding method, was designed and installed on a rear windshield of a commercial sedan. The antenna using the proposed feeding method shows a similar reflection coefficient, and it shows 2 dB increased average azimuth radiation gain compared to that using a conventional sash ground method. These results demonstrate that the proposed feeding method can be applicable for integrating multiple antennas in a rear windshield.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.2
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• pp.34-41
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• 2009

The latest vehicle yields a superior safety and reduction of driving burden by monitoring the driving state of vehicle and its environment with various sensors. To detect other vehicles and objects of the rear left and right-side blind spot area of driver, provide the information about a existence of objects inside the blind spot, and give a signal to avoid collision, this study proposes the intelligent outside rear-view mirror system. This task has substantially complicated several factors. For example, the size, geometry and features of the various vehicles which might enter the monitored zone is varied widely and therefore present various reflective characteristics. This study proposes the optimal specification and configuration of optical system and IR array sensor of blind spot detection system, and shows the results of the performance evaluation of developed system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.5-6
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• 2006

There are typically applied on both rear and front sides of electrical contacts to the solar cell. The front contact formation is particularly sensitive to many parameters. Accordingly patterning of front grid line is an important factor of solar cells. This paper describe the electrical conversion efficiency, inclusive of shading loss that gives various spacing between front metal grid lines. In experiments with variation of spacing. It was verified that the wide spacing of grid fingers could increase the series resistance, also the narrow spacing of grid fingers also implies a grid with a higher density of grid fingers. The sunlight of incidence was more of reflection by grid fingers. In result, the short circuit current, which contribute to conversion efficiency was decreased, because maximum power input was reduced and increase the series resistance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.727-732
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• 2014

The goal is to find the position of the sound source with the TRM at reflections and refractions environment. The Fermat's principle applied to the ray tracing method are expected to follow the acoustic path in order to obtain acoustic distance and transmittance to. Utilizing them in the TRM was confirmed rear reflectance affect on estimated position, resolution and side lobe. And the TRM performance were superior to one of the beam forming techniques.

• Journal of the Semiconductor & Display Technology
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• v.11 no.4
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• pp.1-6
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• 2012

Keeping the polarization direction of the projection light unchanged is of crucial importance for high quality of images on a double-screen 3D projection display system. It has been found that the deposition of oxide layers on the surfaces of scattering polarizer film results in an improvement of polarization maintenance property of the film. The secondary image formed on the front screen by the light scattered from the rear screen decreases by 30% through the application of oxide layers on both surfaces of the screen. Since the oxide layer can also be used as an anti-reflection (AR) coating of the film, this method is very effective for the projection display applications.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.5
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• pp.327-333
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• 2011

Intelligent robots are widely needed in various areas of industry from extremely dangerous environments to service tasks. For autonomous mobile robots, it is significant to move itself safely to a destination point, recognizing its surroundings. Advances in sensor technology and its applications are achieved in order to develop an intelligent robot. In this paper, a mobile robot with a path-finding algorithm is presented. The path-finding algorithm is the one that does not only find a path to designated destination and also recognizes obstacles on the way, calculating its distance. 10 ultrasonic sensor are mounted on the front and rear of the mobile robot to figure out its position. Specular reflection and wide viewing angle, which are inherent characteristics of ultrasonic waves, cause errors in measuring distance.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.421.2-421.2
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• 2016

고효율 태양전지에서 후면 반사 방지막은 장파장대(900nm~1200nm) 빛의 내부 반사를 증가시켜 광흡수도를 개선한다. 태양전지 후면에 박형 절연층 구조를 구성함으로써 특정 파장에서 높은 반사도를 얻을 수 있는 Bragg mirror 구조를 이론적으로 계산할 수 있다. Bragg mirror 구조를 이용하여 태양전지의 후면 반사층(Rear reflector layer)을 형성함으로써 태양전지 내부의 광흡수도를 개선할 수 있다. 후면 반사 방지막(Rear anti-reflection coating)으로 사용되는 Al2O3와 SiOxNy 또는 이러한 두 가지 물질의 겹층 구조를 구성하여 장파장대 빛의 반사도 차이에 의한 광흡수도 개선 정도를 광학 시뮬레이션을 통해 계산하였다. 광학 시뮬레이션은 TCAD를 이용하였으며 두 가지 겹층 구조에서 각 반사 방지막의 두께에 따른 단락 전류(Jsc)의 개선 정도, 후면 반사층 두께의 최적화 조건을 계산하였다. 후면 반사방지막을 제외한 기본적인 태양전지 구조는 n-type PERC 구조를 사용하였으며, 후면 반사방지막만의 광학적 특성을 살펴보기 위해 전극은 광학적으로 투명하다고 가정하였다. 반사방지막 두께의 범위는 Al2O3(5-30nm), SiNx(150-300nm), SiOxNy(150-300nm)에서 수행하였으며, 각각 1nm, 2nm 간격으로 진행하였다. Al2O3/SiOxNy 구조에서는 단락 전류가 32.45-32.87mA/cm2 값을 가진다. Al2O3/SiNx 구조에서는 단락 전류가 32.59-32.87mA/cm2 값을 가진다. 결론적으로, 후면 반사방지막의 겹층 구조를 통해 광흡수도를 증가 시킬 수 있으며, TCAD 시뮬레이션을 통하여 입사되는 태양광 스펙트럼에 최적화된 구조를 설계할 수 있다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.3
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• pp.182-187
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• 2018

In this study, 20.8% of a p-type Si bifacial solar cell was used to develop a photovoltaic (PV) module to obtain the maximum power under a limited installation area. The transparent back sheet material was replaced during fabrication with a white one, which is opaque in commercial products. This is very beneficial for the generation of more electricity, owing to the additional power generation via absorption of light from the rear side. A new model is suggested herein to predict the power of the bifacial PV module by considering the backside reflections from the roof and/or environment. This model considers not only the frontside reflection, but also the nonuniformity of the backside light sources. Theoretical predictions were compared to experimental data to prove the validity of this model, the error range for which ranged from 0.32% to 8.49%. Especially, under $700W/m^2$, the error rate was as low as 2.25%. This work could provide theoretical and experimental bases for application to a distributed and microgrid network.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.112-116
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• 2022

The demand for a rear reflective material is continuing according to the expansion of the bifacial soar module and the effect on the re-reflection of the ground using a back sheet that is not used due to the increase in the supply of the bifacial solar module was confirmed. For analysis, a bifacial solar module with an output of 445W was connected to a single inverter of 49.84kW, and analysis of each two inverters was carried out. In the analysis of the results, it was confirmed that the generation amount increased by 5.25% compared to the case where the back sheet reflective film was not installed and it was confirmed that the increase in the generation amount was the noon time when strong solar radiation was irradiated, not the time of sunrise and sunset.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.3
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• pp.75-80
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• 2019

Silicon solar cells have been widely used as a most promising renewable energy source due to eco-friendliness and high efficiency. As modules of silicon solar cells are connected in series for a practical electricity generation, a large voltage of 500-1,500 V is applied to the modules inevitably. Potential-induced degradation (PID), a deterioration of the efficiency and maximum power output by the continuously applied high voltage between the module frames and solar cells, has been regarded as the major cause that reduces the lifetime of silicon solar cells. In particular, the migration of the $Na^+$ ions from the front glass into Si through the anti-reflection coating and the accumulation of $Na^+$ ions at stacking faults inside Si have been reported as the reason of PID. In this research, the thickness effect of $SiO_x$ layer that can block the migration of $Na^+$ ions on the reduction of PID is investigated as it is incorporated between anti-reflection coating and p-n junction in p-type PERC solar cells. From the measurement of shunt resistance, efficiency, and maximum power output after the continuous application of 1,000 V for 96 hours, it is revealed that the thickness of $SiO_x$ layer should be larger than 7-8 nm to reduce PID effectively.