• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.181-186
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• 2019

In order to reduce the fossil fuels consumed in conventional commercial independent diesel generators in the same environment as the island area, it is necessary to develop a photovoltaic system that will bear more than 40% of the independent system capacity. For this development, it is necessary to develop a high-capacity inverter that can improve the stability of the independent system installed in the island area and supply high-quality power to the load. In addition, the EMS power generation control system for the independent grid photovoltaic power generation system is a parallel operation power control system of the diesel generator connected with the solar power generation system. It controls the output of the diesel generator according to the load ratio and the solar power generation, A stable supply system is needed. This independent grid photovoltaic generation system can increase the solar power supply to the independent system area and increase the power stability of the independent system and further reduce the use of fossil fuel due to the ineffective power control of the independent system. It is expected that the economy will be secured early.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.6
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• pp.547-555
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• 2022

Color conversion layer refers to a layer that converts the blue light emitted from the backlight into the red and green light. Heavy metal-free quantum dots and perovskite nanocrystals have attracted great attention as base materials for color conversion layers due to their outstanding optical characteristics. Here, we review recent advances in the development of color conversion layers based on quantum dots. First, we overview the representative optical characteristics of quantum dots and perovskite nanocrystals, and then introduce printing techniques for color converting layers including photolithography, inkjet printing, and nanoimprinting. Finally, we conclude this review with a brief perspective.

• Korean Journal of Remote Sensing
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• v.39 no.6_2
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• pp.1541-1551
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• 2023

Radiometric calibration is a fundamental step in ocean color remote sensing since the step to derive solar radiance spectrum in visible to near-infrared wavelengths from the sensor-observed electromagnetic signals. Generally, satellite sensor suffers from degradation over the mission period, which results in biases/uncertainties in radiometric calibration and the final ocean products such as water-leaving radiance, chlorophyll-a concentration, and colored dissolved organic matter. Therefore, the importance of radiometric calibration for the continuity of ocean color satellites has been emphasized internationally. This study introduces an approach to improve the radiometric calibration algorithm for the visible bands of the Geostationary Ocean Color Imager-II (GOCI-II) satellite with a focus on stability. Solar Diffuser (SD) measurements were employed as an on-orbit radiometric calibration reference, to obtain the continuous monitoring of absolute gain values. Time series analysis of GOCI-II absolute gains revealed seasonal variations depending on the azimuth angle, as well as long-term trends by possible sensor degradation effects. To resolve the complexities in gain variability, an azimuth angle correction model was developed to eliminate seasonal periodicity, and a sensor degradation correction model was applied to estimate nonlinear trends in the absolute gain parameters. The results demonstrate the effects of the azimuth angle correction and sensor degradation correction model on the spectrum of Top of Atmosphere (TOA) radiance, confirming the capability for improving the long-term stability of GOCI-II data.

• Current Photovoltaic Research
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• v.10 no.1
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• pp.23-27
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• 2022

In this study, we investigate organic-inorganic halide perovskite solar cells with a vacuum thermal evaporated hole transporting layer (NPB/MoO_3-x). By replacing solution process based Spiro-MeOTAD with vacuum thermal evaporation based NPB/MoO_3-x, a thin hole transporting layer was implemented. In addition, parasitic absorption that may occur during the doping process was eliminated by excluding solution process doping. In a solar cell with a thin vacuum thermal evaporated hole transporting layer, the short-circuit current density (Jsc) increased to 23.93 mA/cm², resulting in the highest power converstion efficiency (PCE) at 18.76%. Considering these results, it is essential to control the thickness of hole transporting layer located at the top in solar cell configuration.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.338-339
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• 2020

화력 발전에 의한 전력 생산은 환경오염으로 이어지고 이를 극복하기 위해 태양광 발전 혹은 풍력발전과 같은 신재생에너지원을 이용한 전력 생산이 꾸준히 증가하고 있다. 하지만 신재생에너지는 불규칙적인 전력을 생산할 뿐만 아니라 전력 계통의 도선 및 부하의 임피던스에 의해 계통의 전압 및 주파수가 변동한다. 이러한 문제를 극복하기 위해 계통 연계형 스마트 인버터를 사용하여 신재생에너지를 사용함과 동시에 계통의 안전성을 높일 수 있다. 본 논문은 ESS를 사용한 계통 연계형 스마트 인버터의 Voltage-Watt, Voltage-Var 제어 및 Frequency-Watt 제어를 통해 신재생에너지에 의해 발생하는 계통의 문제를 해결하는 제어 알고리즘을 제안한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.713-716
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• 2008

This paper presents an automatic back-light brightness control system for mobile displays. One of the most important factors in mobile display is the power consumption due to the limited and movable power source. More than 80% of power of the LCD display is consumed by LED bark-light unit (BLU). The target brightness also becomes higher because of its moving picture and high resolution image, so there are some side effects for not only excessive power consumption but also ergonomic inconvenience in dark environment. To prevent this discomfort and reduce power consumption, this paper proposes automatic brightness control (ABC) technique in mobile displays. Developed system contains TFT-LCD panel with built-in photo sensor, driver IC capable of controlling photo sensor, and BLU. Since the photo sensor array built in panel detects automatically outdoor ambient light intensity, the power of BLU in dark environment is reduced. Developed ABC system showed reduced power consumption of 50% in dark environment. We believe that the proposed system is very useful to control power of mobile TFT-LCD.

• The Optical Journal
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• s.114
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• pp.68-70
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• 2008

국내 광산업은 80년대 카메라, 복사기 등 결상기기 중심에서 90년대 이후에는 결상기기와 더불어 레이저 가공기, 광정보기기, 광통신기기 등 광응용기기로 확대 되고 있다. 2005년 기준으로 볼 때 국내 광산업은 세계시장의 약 5.5%를 차지했으며, 정밀 광산업 기술로드맵과 직접 관련되는 광정밀기기, 광정보기기, 광학기기분야의 수입은 68%, 수출이 90%를 차지해 수출역점산업임을 알 수 있다. 따라서 2010년에는 광산업 세계 시장규모가 400조 원 수준에 이를 것으로 예상되는 가운데 이에 대비하여 국내 광산업의 성장기틀을 다질 때이다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.440-444
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• 1995

StereoLithography는 3차원 CAD로 작성된 모델데이타를 이용하여입체조형 실물을 빠르게 제작 하는 Rapid Prototype 기술의 한 방식으로서, 감광성 수지를 자외선 Laser 광에 의해 선택적으 로 경회시켜 원하는 한 단면형상을 이룬후 적층하는 반복작업에 의해 입체 형상을 조형하는 기법 이다. Rapid Prototype 시스템은 제품개발기간 단축과 설계완성도를 높이는 목적으로 최근 산업계에서 그 활용도가 점차 증가하는 추세에 있으며, 3차원 CAD 시스템과 함께 제품개발 체제를 통합화하고 Concurrent Engineering의 실현을 위한 주요한 Tool로써 자리를 잡아가고 있다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.3
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• pp.223-231
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• 2022

Spectroscopies are the most widely used for understanding the crystallographic, chemical, and physical aspects of materials; therefore, numerous commercial and non-commercial software have been introduced to help researchers better handling their spectroscopic data. However, not many researchers, especially early-stage ones, have a proper background knowledge on the choice of fitting functions and a technique for actual fitting, although the essence of such data analysis is peak fitting. In this regard, we present a practical guide for peak fitting for data analysis. We start with a basic-level theoretical background why and how a certain protocol for peak fitting works, followed by a step-by-step visualized demonstration how an actual fitting is performed. We expect that this contribution is sure to help many active researchers in the discipline of materials science better handle their spectroscopic data.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.62.2-62.2
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• 2021

남,북한에 존재하는 다양한 종류의 신재생에너지 분야 중 풍력자원은 지역마다 많은 편차를 가지고 있으나, 2007년에 북한지역의 풍력자원을 분석한 결과 풍부한 자원을 가지고 있는 지역이 많은 것으로 분석되었다. 북한은 과거에도 그렇고 현재에도 전력난으로 많은 어려움을 겪고 있으며, 이를 극복하기 위하여 북한의 국가과학원, 김일성종합대학, 김책공대 등에서 신재생에너지를 활용한 전력난 해소를 위하여 다양한 기술개발을 하고 있다. 따라서, 성공한 신재생에너지 기술을 활용한 태양광 풍력 등을 설치하여 주택이나 공업지역 등에 전력을 공급하고 있다. 그러나 북한의 자본과 기술개발의 한계로 인하여 부품조달 등 공급의 한계성을 가지고 있는 실정에 있다. 최근 남북 학술교류를 통하여 북한의 신재생에너지 개발 현황 및 한계성을 파악할 수 있었으며, 이러한 문제점을 해결하기 위해서는 남한이 가지고 있는 기술력과 북한의 인력을 활용하여 공동개발 및 보급을 촉진할 수 있으리라 사례되며 몇 가지 제안을 하고자 한다.