• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.212-217
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• 2020

The PV power generation system is a comprehensive system that transmits the power generated through a PV panel to a grid connection and is composed of a solar panel, a structure, and an inverter grid connection system. One technology to increase the amount of power generated involves changing the incident angle of sunlight. This study examined the structure and control of a single-axis tracking PV system that increases the amount of power generated by changing the incident angle. The core content is a single-axis control system and technology configured to rotate the solar structure in the east-west direction around the north-south axis. A solar structure that follows the sun from sunrise to sunset in the east-west direction needs to secure structural stability and solar tracking control performance. A single-axis tracking system can generate up to 25% more power.

• Smart Media Journal
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• v.12 no.3
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• pp.49-59
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• 2023

Optical Camera Communication (OCC), known as the next-generation wireless communication technology, is currently under extensive research. The performance of OCC technology is affected by the communication environment, and various strategies are being studied to improve it. Among them, the most prominent method is applying convolutional neural networks (CNN) to the receiver of OCC using deep learning technology. However, in most studies, CNN is simply used to detect the transmitter. In this paper, we experiment with applying the convolutional neural network not only for transmitter detection but also for the Rx demodulation system. We hypothesize that, since the data images of the OCC system are relatively simple to classify compared to other image datasets, high accuracy results will appear in most CNN models. To prove this hypothesis, we designed and implemented an OCC system to collect data and applied it to 12 different CNN models for experimentation. The experimental results showed that not only high-performance CNN models with many parameters but also lightweight CNN models achieved an accuracy of over 99%. Through this, we confirmed the feasibility of applying the OCC system in real-time on mobile devices such as smartphones.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.2
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• pp.182-187
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• 2024

Currently, the most developed new energy source is solar energy. Because solar power is installed outside, it is exposed to many pollutants. Pollutants are causing the characteristics of solar energy to deteriorate. Therefore, this study aims to develop a water-repellent coating to prevent contamination of solar modules. Silica and Titania materials are mainly used as water-repellent coating materials. In this study, it was based on silica and the contact angle characteristics were measured according to the change in the amount of silica and ammonia water added and the number of coatings. As a result of the measurement, it was confirmed that the contact angle was more than 60 degrees when 0.5 mol of TEOS was added to 50 mL and 0.15 M when 1 mL of ammonia water was added to 296.47 ml of distilled water. And it was confirmed that the contact angle improved when the number of coatings was applied twice. A water-repellent coating material was applied to low iron tempered glass used to protect dye-sensitized solar cell modules. The characteristics of the module were measured after spraying DI-Water on low-emission tempered glass with a water-repellent coating. As a result of the measurement, the efficiency of the module without application, the efficiency of the module coated once, and the module coated twice were 4.87%, 4.90%, and 4.91%, respectively. It was confirmed that the efficiency of the module increased by applying water-repellent coating. As a result of this study, it is determined that the water-repellent coating material will help improve solar power generation efficiency and lifespan by being self-cleaning and non-reflective.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.2
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• pp.100-107
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• 2021

An agrivoltaic system (AVS) is a system of innovation that comprises productions of photovoltaic power and agricultural crops on the same area. However, the decline in crop yield will be fatally occurred because the pigments of crop absorbs less light energy under AVS. In addtion, the photosynthetic capacity of crop grown under the partial shading of AVS is not well reported. In this study, the electron transport rate (ETR) and non-photochemical fluorescence quenching (NPQ) of soybean and rice under the AVS in Boseong and Naju was investigated using chlorophyll fluorescence measurement. The ETR value of soybean and rice under AVS were not significantly differed by location. It represents that the photophosphorylation rate of the crops is not critically different. It means that the decreases in total photosynthesis under AVS were mostly affected by the amount of light absorbed by leaves. Under AVS the photosynthesis of crops will be lower than field crops grown in open fields. This is because the crops under AVS observed higher NPQ, which means that the available energy cannot distribute to photophosphorylation reaction.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.32.2-32.2
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• 2010

본 연구에서는 고출력, 고휘도를 위해서 개발되고 있는 수직형 LED소자의 광출력향상을 위한 나노 패터닝 공정을 진행하였다. 수직형 LED는 기존 측면형 LED에 비해서 열방출 특성이 우수하고 대면적 칩으로 제작이 가능하기 때문에 높은 광출력이 필요한 조명 분야로의 적용이 가능하다. 하지만 수직형 LED 역시 기존 측면형 LED와 마찬가지로 질화갈륨 및 외부 공기와의 계면에서 전반사가 심하기 때문에 광추출효율이 낮은 문제점이 있으며 이를 해결하는 것이 큰 이슈가 되고 있다. 이를 해결하기 위해서 광결정 패턴을 LED 소자에 형성하여 광추출효율을 향상시키려는 연구가 활발히 진행되고 있으나 아직까지 수직형 LED 웨이퍼 전면적에 균일한 패턴을 형성할 수 있는 기술 개발이 미진한 상황이다. 본 연구에서는 유연 고분자 몰드를 이용한 대면적 나노 임프린팅 및 나노 프린팅 기술을 통해서 2 inch 수직형 LED 웨이퍼 전면적에 균일한 패턴을 전사하는 공정을 진행하였다. 구체적으로는 나노임프린트 및 건식식각 공정을 통해서 수직형 LED의 n형 질화갈륨 층에 높은 가로세로비의 광결정 패턴을 형성하였으며 이를 통해서 약 40% 정도의 광출력이 향상되었다. 또한 고 굴절률의 산화아연 나노 패턴 형성공정을 대면적 LED 기판에 시도하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.27.2-27.2
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• 2009

현재 질화물 계 발광다이오드는 액정소자의 백라이트유닛, 모바일폰, 차량용램프, 교통신호등 등 다양한 장치의 광원으로 사용되고 있으며, 그 응용분야는 앞으로도 크게 확대되는 추세에 있다. 이는 발광다이오드의 저전력, 장수명, 친환경적인 장점에 의한 것으로, 일반 조명용 광원으로 사용하기 위한 기술개발이 활발히 진행 중이다. 하지만 질화물 계 발광다이오드를 미래의 조명용 광원으로 사용하기 위해서는 광출력이 보다 향상되어야 한다. 발광다이오드의 광출력을 저하시키는 요인으로는 다양한 문제점이 있지만 특히 낮은 광추출특성으로인한 광출력저하 문제를 해결해야 한다. 본 연구에서는 질화물 계 발광다이오드의 광추출특성을 향상시키기 위해서 나노임프린트 리소그래피 공정을 도입하였다. UV 나노임프린트 리소그래피 공정을 통해서 p형 질화갈륨 및 인듐주석산화물 투명전극 층에 sub-micron 급 광결정패턴을 형성하였으며, 광루미네선스와 전기루미네선스 측정을 통하여 광결정패턴으로 인한 광출력 특성을 분석하였다.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.700-703
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• 2012

본 논문은 태양광 모듈을 이용한 비닐하우스 자동제어시스템으로 Zigbee를 이용한 근거리 무선 인터페이스 환경, 농작물 생육 DB에 따른 비닐하우스 제어환경 및 비닐하우스 이상 유무를 파악하기 위한 모니터링하여 비닐하우스의 개수와 관계없이 하나의 서버에서 다수의 클라이언트를 양방향으로 제어함과 동시에 모니터링을 수행할 수 있는 시스템이다. 따라서, router, end는 임의의 ID를 가지고 특정한 비닐하우스에 대한 상태를 파악할 수 있으며 비닐하우스에 대하여 제어가 독립적으로 가능하므로 특정 비닐하우스에 대한 특징을 살려 사용자가 원하는 제어를 실시간 처리됨을 확인하였다.

• Journal of Advanced Navigation Technology
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• v.23 no.1
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• pp.61-68
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• 2019

Underwater wireless light communication system is quite necessary to retrieve recorded data from underwater devices or the black box without taking back it body. In this paper, a research on the light sensor technology in underwater wireless light communication under turbid sea was studied. A noise source under turbid sea for light communication was analysed, and a sensor system for light sensing using the reference light signal to remove the noises and to improve the output swing power wasstudied. Also, an underwater communication system was manufactured to validate the good performance of the development system, and using the system, the good performance of the developed system was validated through the light communication test in the tank containing the turbid sea water was presented.

• Korean Journal of Optics and Photonics
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• v.32 no.5
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• pp.235-243
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• 2021

Photobiomodulation (PBM)-based therapy, which uses a phenomenon in which a light source of a specific wavelength band promotes ATP production in mitochondria, has attracted much attention in the fields of biology and medicine because of its effects on wound healing, inflammation reduction, and pain relief. Research on PBM-based therapy has mainly used lasers and light-emitting diodes (LEDs) as light sources and, despite the advantages of organic light-emitting diodes (OLEDs), there have been only a few cases where OLEDs were used in PBM-based therapy. In this research, the skin-care effect of PBM was analyzed using red (λ = 620 nm), green (λ = 525 nm), and blue (λ = 455 nm) OLED lighting modules, and was compared to the PBM effect of LEDs. We demonstrated the PBM-based skin-care effect of the red, green, blue OLED lighting modules by measuring the increase in the amount of collagen type-1 synthesis, the inhibition of melanin synthesis, and the suppression of nitric oxide generation, respectively.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.36-38
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• 2020

해상 ICT의 발전과 e-Navigation 도입 및 자율운항선 도입에 따라 해상 통신망의 종류와 범위가 확장되고 있고 디지털 항로표지 서비스의 필요성이 증가하고 있다. 어선원의 고령화, 해안 배후 단지의 발전에 의한 배후광, 기상여건 및 진보된 선내 항해 장비 사용 미숙 등으로 항로표지의 시각적·전자적 인지력이 저하되어 선박 안전 운항이 담보하기 어려운 상황에서 선박의 운항 상황 및 주변 해역 운항 상황·지리적 여건을 고려한 맞춤형 가상 디지털 항로표지 서비스는 항로표지의 전자적 식별을 용이하게 하고 안전 운항 유도 서비스로 해양 사고 예방에 도움이 될 것이다. 본 연구에서는 자율운항선 대응을 위한 디지털 항로표지 서비스 및 선박 운항 상황·지리적 여건을 고려한 적극적인 맞춤형 가상 디지털 항로표지 서비스 시스템의 설계방안을 제시하였다.