• Journal of Bio-Environment Control
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• v.28 no.2
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• pp.143-149
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• 2019

This study was conducted to investigate the graft-taking and growth of grafted cucumber seedlings as affected by light quality and blink cycle of LED modules. Four light quality treatments, namely blue, red, blue+red, white LED and four blink cycle levels of 5s/5s, 7s/3s, 9s/1s and control were provided to investigate the effect of lighting quality and blink cycle on the graft-taking and growth of grafted cucumber seedlings. Photoperiod for the control was 12/12 h. Photosynthetic photon flux, air temperature, and relative humidity for healing were maintained at $100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, $25^{\circ}C$, and 90%, respectively. There was no significant difference in graft-taking of grafted cucumber seedlings according to light quality except the blue LED with the blink cycle of 5s/5s. Regardless of the blink cycle, there was no significant difference in graft-taking of cucumber seedlings healed under red, blue+red, and white LED modules. These results implied that the effects of light quality and blink cycle on the graft-taking were not significant. Differences in the leaf length, leaf area, and fresh weight of cucumber seedlings healed blue or red LED with the blink cycle of 9s/1s were found to be significant. There was no significant effect of the blink cycle on the growth of cucumber seedlings healed under white LED modules. The prices of white LED are gradually falling due to increased demand. Considering the manufacturing unit price of white LED modules, the cost savings of 10-15% are expected as compared to the conventional blue/red LED modules. Therefore, it was concluded that the use of white LED modules will be economical as an artificial lighting sources for healing of grafted seedlings.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.273-281
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• 2019

The energy consumed by buildings among the total national energy consumption is more than 10% of the total. For this reason, Korea has adopted the zero energy building policy since 2025, and research on the energy saving technology of buildings has been demanded. Analysis of buildings' energy consumption patterns shows that lighting, heating and cooling energy account for more than 60% of total energy consumption, which is directly related to solar power acquisition and window opening and closing operation. In this paper, we have developed a low - power IoT sensor module for window system to transfer acquired information to building energy management system. This module transmits the external environment and window opening / closing status information to the building energy management system in real time, and constructs the network to actively take energy saving measures. The power used in the module is designed as an independent power source using solar power among the harvest energy. The topology of the power supply is a Buck converter, which is charged at 4V to the lithium ion battery through MPPT control, and the efficiency is about 85.87%. Communication is configured to be able to transmit in real time by applying WiFi. In order to reduce the power consumption of the module, we analyzed the hardware and software aspects and implemented a low power IoT sensor module.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.453-453
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• 2009

Wafer 태양전지와 Back sheet 및 기타 소재를 사용하는 기존의 Photovoltaic Module은 투과성이 존재하지 않으므로 본 논문에서는 태양전지 모듈의 투과특성을 발휘할 수 있는 Glass to Glass (GtG) Type의 Photovoltaic module에 대해 그 투과 특성 및 효율과의 관계를 분석하였다. 먼저 Module용 소재 중 Poly vinyl butyral (PVB) 및 Ethylene vinyl acetate(EVA) sheet의 Transmittance와 Haze 특성을 분석하였다. GtG 타입의 Photovoltaic Module은 약 90%정도의 투과율을 갖는 강화유리 및 Haze가 없는 PVB sheet를 사용하여 1m $\times$ 1m 크기로 제작하였다. GtG 타입으로 제조한 모둘 중 Cell 16EA를 사용한 모듈은 Cell 25EA를 사용한 모듈에 비해서 36% 투과율이 증가하였으나 효율 면에서 38%감소하였다. 최종적으로 GtG 타입 Module의 효율과 투과율에 관련된 식을 각각 정립하였다.

• Journal of Satellite, Information and Communications
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• v.10 no.1
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• pp.62-66
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• 2015

This paper introduces various applications and contents of digital signage, and analyzes conventional communication techniques to increase communication range. To realize digital signage in long distance, this paper proposes a hybrid modulation scheme and analyzes its performance. To verify its performance in real channel environment, we mapped symbols and experimented data transmission and reception with a visible light communication module with USRP. As a result, we confirmed a data receiving range and power of transmission and reception of the hybrid modulation mode. Also, we showed that the proposed modulation scheme has better performance of communication range and power efficiency than that of the conventional QAM technique.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.345-353
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• 2005

We proposed a new and cost-effective method fer assembling holographic pickup modules without any high resolution vision system. Assembling was accomplished by adjusting photodiode package only, leading to a low cost, holographic pickup module. Focus and tracking error signals were simply determined by comparing spot sizes and by using the 3 beam method, respectively, based on four-sectional holographic optical elements. In experiment, we assembled a hologram module and estimated performance of the proposed method fur a holographic pickup module used in compact disc system.

• Korean Journal of Optics and Photonics
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• v.27 no.4
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• pp.127-132
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• 2016

In this paper, a trench structure was fabricated by femtosecond-laser machining to eliminate thermal crosstalk in a multichannel variable optical attenuator (VOA), to prevent decreasing attenuation efficiency of the VOA. Trenches of a variety of widths and depths were fabricated on the VOA chips by femtosecond-laser processing. After the machining, attenuation according to current change was observed in each VOA chip module with trenches. As a result, we could observe high responsivity of attenuation and low power consumption, and that the heat of each channel barely influenced other channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.11
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• pp.2238-2248
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• 1994

In this paper, we analyze a Microwave Amplifier Ultra-Wideband charateristic to apply Multi-Giga b/s optical receiver preamplifier in high speed optical communication system. To obtain frequency expanding effect. we analyze the frequency gain degradation effects of capacitances in the GaAs MESFET small-signal equivalent circuit and design Feedback amplifier Module(FAM) which has inductor peaking elements to compensate its effects and to expand frequency band. We derive optimum inductor peaking values in order to get flat gain in frequency band. The input and the output impedances of FAM are matched by Real Frequency Method and we design one and two stage ultra wideband microwave amplifier. With simulation results, it show $6.36\sim6.86dB$ and $9.1\sim10.3dB$ gains and execllent gain flatness in $0.5\sim12GHz$ respectively.

• Journal of the Korean Institute of Gas
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• v.15 no.4
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• pp.51-55
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• 2011

This paper describes the temperature compensation algorithm using thermopile detector for nondispersive infrared methane gas sensor. From the output voltage of thermistor that is attached onto the infrared detector, the ambient temperature was extracted. The effects of temperatures on the properties of sensor module (the characteristics of narrow bandpass filter, optical cavity and infrared lamp, and gas absorption coefficient times optical path length) have been introduced in order to implement the temperature compensation algorithm. Even though the measurement error of developed sensor module was in the range of $\pm$ 1,500 ppm, after programming the temperature compensation algorithm, the developed sensor module shows a high accuracy less than +180 ppm error within $20^{\circ}C$ temperature variation.

• KIEAE Journal
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• v.11 no.3
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• pp.69-73
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• 2011

In general, there are two types of PVT module depending on the existence of the glass in front of PV module: glazed and unglazed. On the other hand, the water-type PVT modules can be classified into two types, according to absorber type: the sheet-and-tube absorber PVT module and the fully wetted absorber PVT module. The aim of this study is to analyze the electrical and thermal performance of a water-type PVT module with fully wetted absorber. For this study, a prototype of unglazed PVT module with fully wetted absorber was designed and built, and both the thermal and electrical performances of the prototype module were measured in outdoor conditions. A conventional mono-crystalline Si PV module was tested alongside the PVT module for their electrical performance comparison. The results showed that the thermal efficiency of the PVT module was average 51% and its electrical efficiency was average 14.3% in mean fluid temperature $10-40^{\circ}C$, whereas the electrical efficiency of the conventional PV module was average 12.6%. It is found that the electrical efficiency of the PVT module was improved by approximately 14% compared to that of the PV module. The temperature of PVT module becomes lower due to the cooling effect by the fluid of the absorber. The results proved that the electrical efficiency was higher when the mean fluid temperature was lower.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.363-363
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• 2013

태양광 발전산업에서 현재 주류인 결정 실리콘 태양전지의 변환효율은 꾸준히 향상되고 있으나, 태양전지의 가격이 매년 서서히 하강되고 있는 실정에서 결정질 실리콘 가격의 상승 등으로 부가가치 창출에 어려움이 있으며, 생산 원가를 낮출 수 있는 태양전지 제조기술로는 2 세대 태양전지로 불리는 박막형이 현재의 대안이며, 특히 에너지 변환 효율과 생산 원가에서 장점이 있는 것이 CIGS 박막 태양전지로 판단된다. 화합물반도체 베이스인 CIGS 박막태양전지는 연구실에서는 세계적으로 20.3% 높은 효율을 보고하고 있으며, 모듈급에서도 13% 효율로 생산이 시작되고 있다. 국내에서도 연구실 규모 뿐만 아니라 대면적(모듈급) CIGS 박막태양전지 증착용 장비, 제조공정 등의 기술개발이 진행되고 있다. CIGSe2를 광흡수층으로 하는 CIGSe2 박막 태양전지의 구조는 여러 층의 단위박막(하부전극, 광흡수층, 버퍼층, 상부투명전극)을 순차적으로 형성시켜 만든다. 이중에 소다라임유리를 기판으로 하는 하부전극은 Mo 재료를 스퍼터링 방법으로 증착하여 주로 사용한다. 하부전극은 우수한 전기적 특성이 요구되며, 주상조직으로 성장하여야 하며, 고온 안정성 확보를 위하여 기판과의 밀착성이 좋아야하고 또한 레이저 패턴시 기판에서 잘 떨어져야 하는 특성을 동시에 가져야 한다. 본 연구에서는 대면적 CIGSe2 박막태양전지에서 요구되는 하부전극 Mo 박막의 제작과 그 특성에 대해 평가하고, 최종적으로 대면적 CIGSe2 박막태양전지 공정에 적용 그 결과를 논하고자 한다.