• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.5
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• pp.342-348
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• 2021

The PV module of solar power systems requires maximum power point tracking (MPPT) technique because the power-voltage and current-voltage characteristics vary depending on the surrounding environment. In addition, the 120 Hz ripple voltage on the DC-Link is caused by the imbalance of the system voltage and current. The effect of this 120 Hz ripple voltage reduces the efficiency of the power generation system by increasing the output current distortion rate. Increasing the capacity of DC-Link can reduce the 120 Hz ripple voltage, but this method is inefficient in price and size. We propose a technique that detects 120 Hz ripple voltage and reduces the effect of ripple voltage without increasing the DC-Link capacity through a controller. The proposed technique was verified through simulations and experiments using a 1 kW single-phase solar power system. In addition, the proposed technique's feasibility was demonstrated by reducing the distortion rate of the output current.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.5
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• pp.207-217
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• 2018

Recently, the importance of energy demand management, particularly peak load control, has been increasing due to the policy changes of the Second Energy Basic Plan. Even though the installation of distributed generation systems such as Photovoltaic and energy storage systems (ESS) are encouraged, high initial installation costs make it difficult to expand their supply. In this study, the power consumption of a university building was measured in real time and the measured power consumption data was used to calculate the optimal installation capacity of the Photovoltaic and ESS, respectively. In order to calculate the optimal capacity, it is necessary to analyze the operation methods of the Photovoltaic and ESS while considering the KEPCO electricity billing system, power consumption patterns of the building, installation costs of the Photovoltaic and ESS, estimated savings on electric charges, and life time. In this study, the power consumption of the university building with a daily power consumption of approximately 200kWh and a peak power of approximately 20kW was measured per minute. An economic analysis conducted using these measured data showed that the optimal capacity was approximately 30kW for Photovoltaic and approximately 7kWh for ESS.

• International Journal of Precision Engineering and Manufacturing-Green Technology
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• v.5 no.5
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• pp.623-630
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• 2018

The renewable energy systems have been in the spotlight as an alternative for environmental issues. Therefore, the governmental policies are being implemented to spread of promote power generation system using renewable energy in various countries around the world. In addition, Korea has also developed a policy called the power trading contract which can profit from electricity produced from renewable power generation system through Korea Electric Power Corporation (KEPCO) and Korea Power Exchange (KPX). As a result, the power trading contracts can trade power after self-consuming in-house by using small-scale renewable power system for residential customers as well as electricity retailers. The power trading contracts applicable as a small-scale power system have a 'Net metering (NM)' and a 'Power Purchase Agreement (PPA)', and these two types of power trading contracts trade surplus power, but payment method of each power trading is different. The microgrid proposed in this paper is based on grid connected microgrid using Photovoltaic (PV) system and Energy Storage System (ESS), that supplied power to residential demand, we evaluate the operation cost of microgrid by power demand in each power trading contracts and propose the appropriate power trading contracts according to electricity demand.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.4
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• pp.1-14
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• 2021

Recently, various renewable systems have been developed and applied in Korea. However, there are many systems which were not utilized in real buildings or not widely spread in the market. Furthermore, the attention of most users focused on several certain system such as PV or solar system. Therefore, this research aims to find user's needs for renewable energy based on perception surveys to improve the acceptance of technology in line with the world's energy flow. The survey was conducted by classifying respondents by various criteria, and the results were analyzed using AHP technique and CVM technique, focusing on preference and acceptance. According to the results of the survey, it was found that the people felt the need for renewable energy but lacked knowledge about renewable energy compared to the various government-implemented renewable energy supply policies. Therefore, a government-level policy is needed so that the people can have universal knowledge about renewable energy system.

• Asia pacific journal of information systems
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• v.28 no.4
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• pp.320-349
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• 2018

Purpose: The application of IoT is finding continuous acceptance in our daily lives, particularly, smart speakers are making life easier and convenient for consumers. This research aims to develop and test an integrated model of factors influencing consumer's adoption of voice-enabled IoT devices. Design/methodology/approach: Based on the VAM, an integrated voice-enabled IoT device adoption model is proposed. Gender differences on five constructs relating with perceived value (perceived usefulness, perceived enjoyment, perceived security risk, perceived technicality and perceived cost) was also examined through PLS-MGA technique. The usage experience of consumers was also controlled in the integrated VAM. Findings: Result shows that Perceived-Usefulness, Perceived-Enjoyment and Perceived-Cost have a strong effect on Perceived-Value. However, Perceived-Technicality and Perceived-Security-Risk are non-influential and have no significant effect on PV. Additionally, Perceived-Value and Social-Influence plays a significant role in predicting adoption intention. Gender differences also exist in consumers perception of usefulness, enjoyment and cost. In comparison to the basic value-based adoption model, the integrated model provides more insight on consumers adoption of voice-enabled IoT devices. Originality/value: Using an integrated model, this study is one of the first scholarly attempt at modelling the influential factors for adopting smart speakers i.e., voice-enabled IoT devices, with implications for improved adoption.

• Animal cells and systems
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• v.7 no.4
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• pp.337-343
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• 2003

Methyl jasmonate (MeJA) is a signal molecule in the activation of defense responses in plants. In this study, we isolated 15 MeJA-inducible genes by subtractive hybridization. These genes encode two myrosinase-binding proteins, five lipase-like proteins, a polygalacturonase inhibitor, a putative chlorophyll-associated protein, a terpene synthase, a dehydroascorbate reductase, an ascorbate oxidase, a cysteine protease, an O-methyltransferase, and an epithiospecifier protein. Northern analysis showed that most of the Chinese cabbage genes are barely expressed in healthy leaves, but are strongly induced by MeJA treatment. We also examined whether these MeJA-inducible genes were activated by ethethon, BTH, and Pseudomonas syringae pv. tomato (Pst), a nonhost pathogen of Chinese cabbage. The results showed that none of the MeJA-inducible genes was strongly induced by ethephon or by BTH. The genes encoding lipase-like proteins and a myrosinase-binding protein were weakly induced by Pst. Other MeJA-inducible genes were not activated at all by the pathogen.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.183.1-183.1
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• 2010

Recently, the increased interest in environmental issues has led to extensive research for development of green energy generation systems. However, only one type of generation system may not be sufficient for stand-alone mode because it cannot cope with the irregularity of weather condition. A hybrid generation system is able to make up for the weakness of each system. In this paper, a stand-alone hybrid wind/PV system is developed that can guarantee the stable energy supply. The system is suitable for power supply under 50W, and a vertical savonius type of blade was designed and applied for the wind generation system.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.635-638
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• 2001

Photovoltaic (PV) pumping systems with maximum power point tracking (MPPT) technique aims at obtaining the highest possible power to the pump under various insolation and temperature, thus overcomes the mismatch between the photovoltaic panel and the pumping load. A simple method of tracking the maximum power points and forcing the system to operate close to these points is presented in this paper. The MC68HC908GP32 micro control unit (MCU) is employed to implement the proposed MPPT controller. Experimental results will also show the performances of the photovoltaic pumping system with the MPPT technique.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.93-107
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• 1997

A solar cell is a device which converts solar energy into electricity without any polluting by-product. Solar cells are useful when they are connected together to form modules. Total production of PV modules worldwide jumped 20 % in 1995 to reach a new record 84.8 MW. In this paper, the recent market trends in photovoltaic industries, principles and characteristics of solar cells and photovoltaic systems are reviewed.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.80-84
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• 2010

본 논문에서는 기존의 배전계통에 연계된 태양광전원에서 발생하는 양방향 보호협조에 대한 문제점을 분석하였다. 모의배전계통과 통합 보호기기장치, 모의 태양광전원장치로 구성된 태양광전원용 보호협조시험장치를 제작하여, 단락사고시험(OCR)과 지락사고시험(OCGR)에 대한 보호기기의 특성시험을 수행하였다. 태양광전원 연계에 의한 사고전류 공급으로 보호기기의 정정치 변동과 보호기기의 오동작, 부동작에 대한 동작특성을 분석하여, 기존의 배전계통에 연계된 태양광전원의 문제점을 분석하고, 그 대안을 제시하였다.