• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.675-680
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• 2012

Wind energy is currently the fastest growing source of renewable energy used for electrical generation around the world. Wind farms are adding a significant amount of electrical generation capacity. The increase in the number of wind farms has led to the need for more effective operation and maintenance. CMS(Condition Monitoring System) can be used to aid plant operator in achieving these goals. Its aim is to provide operators with information regarding th e health of their machine, which in turn, can help them improve operation efficiency. In this work, wind turbine fault diagnostic algorithm which can diagnose the mass unbalance and aerodynamic asymmetry of the blades is proposed. Proposed diagnostic algorithm utilizes both FFT(Fast Feurier Transform) of the signal from accelerometers installed inside of nacelle and simple diagnostic logic. Furthermore, to verify the applicability of the proposed system, 3W small sized wind turbine system is tested and physical experiments are carried out.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.440-440
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• 2018

홍수피해의 위험성이 증가하고, 발생 시기가 불규칙해짐에 따라 보다 효과적인 홍수위험관리가 요구되며, 최적의 홍수피해저감대책을 수립하기 위해서는 다양한 홍수피해저감 대책들에 대해서 비용대비 피해저감효과 분석이 필요하다(FLOODsite, 2007). 홍수피해저감효과를 분석하기 위해서는 수리 수문학적 분석을 통한 피해범위와 침수심 등 피해규모를 분석함과 함께 피해규모에 따른 홍수피해액 추정이 가능해야 하며, 이를 통해 홍수피해저감 대책에 대한 비용대비 효과분석 수행이 가능하다(Kim et al., 2014). 국내에서 많이 적용되고 있는 다차원법은 침수편입율을 산정하고 건물에 대해서 손상률에 해당하는 피해율이 제시되어 있으며, 이를 이용하여 구조물과 내용물에 대해 피해액을 추정할 수 있다(Choi et al., 2006a; Choi et al., 2006b; Yi et al., 2010). 그러나, 단독주택, 아파트, 연립주택 등 주택 이외 다른 용도의 건물에 대해서는 손상함수가 없어 우리나라 여건에 맞는 공공건물에 대한 손상함수 개발이 필요한 상황이다. 본 연구에서는 실제 피해지역의 자료들을 토대로 공공건물 용도별 침수심별 손상함수를 개발하고 적용하였다. 공공건물에 대한 손상함수 개발을 위해서는 많은 피해자료의 수집이 필요하나, 실제 공공건물의 경우 다양한 건물유형으로 인하여 유형별 침수사례가 많지 않은 상황이다. 이로 인하여 현장조사에 의한 침수현황 조사는 한계가 있기 때문에 보험가입자에게 사고로 인하여 손해가 발생했을 때 그 손해액을 결정하고 보험금을 산정하는 업무를 수행하는 손해사정사들을 통해 여러 가지 공공건물을 대상으로 침수심별 손상률에 대한 설문 조사를 실시하였다. 본 연구를 통해 공공건물에 대한 손상함수의 개발절차, 침수심별 손상함수의 개발결과, 보완과정 그리고 손상함수의 적용결과에 대한 국내외 기법과의 비교 결과를 제시하였다. 적용결과 본 연구에서 현장 조사 기반으로 개발한 손상률을 적용한 경우 국내 실제 피해액을 가장 잘 반영하는 것으로 분석되었는데, 다만 동일 건물용도(예컨대 공공업무시설)일지라도 바닥재 등 마감재 재질이 건물마다 다르며, 건물별로 공간 활용 여건이 다양하여 동일한 침수심에 대해서 피해액의 변동폭이 크게 발생 되어 동일한 침수심에 대한 피해내용이 달라져 변동폭이 크게 발생되는 한계가 발생하였다. 향후 보다 많은 피해사례를 지속적으로 조사할 필요가 있으며, 이를 통해 손상함수를 개선하기 위한 연구가 계속 진행되어야 할 것이다.

• Journal of Digital Convergence
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• v.16 no.11
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• pp.1-15
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• 2018

The purpose of this study is to analyze bibliographic information of Busan and other cities' reports for urban development initiative and identify the strategic fields for future smart city plan. Text mining method is used in this study to extract keywords and identify the characteristics and patterns of information in urban development reports. As a result, in earlier stage, Busan city focused on service creation for industrial development but there are lack of discussions on the linkage of information systems with ICT technology. However, recent urban planning in Busan contained various contents related to integrated connections of infrastructure, ICT system, and operation management of city in the specific fields of traffic, tourism, welfare, port/logistics, culture/MICE. This results of study is expected to provide policy implications for planning the future urban initiatives of smart city development.

• Membrane Journal
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• v.31 no.6
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• pp.384-392
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• 2021

Growing pollution due to industrialization leads to difficulties in survival of mankind. Generation of clean water from wastewater by membrane separation process is emerging cost efficient technology. Membrane prepared from renewable resources are in lots of demand to reduce burden on synthetic polymers which is one of the source of environmental pollution. Bacterial cellulose (BC) is very pure and distinct form of cellulose nanofibrils (CNF). Nanopapers prepared from CNF are used ad ultrafiltration (UF) and nanofiltration (NF) membrane for different applications. High crystallinity of BC gives rise to excellent mechanical property, an essential criterion for wastewater treatment membrane. In this review, BC based membrane for application in dye, oil, heavy metal and chemical removal from wastewater is discussed.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1105-1112
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• 2022

Field data monitoring systems such as renewable energy generation and smart farm integrated control are developing from PC and server to mobile first, and various wireless communication and application services have emerged with the development of IoT technology. Low-power wide-area networks are services optimized for low-power, low-capacity, and low-speed data transmission, and data collected in the field is transmitted to designated storage servers or cloud-based data platforms, enabling data monitoring. In this paper, we implement an IoT repeater that collects field data with a single device and transmits it to a wireless carrier cloud data flat using a low-power wide-area network, and a monitoring app using it. Using this, the system configuration is simpler, the cost of deployment and operation is lower, and effective data accumulation is possible.

• Plant Journal
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• v.18 no.2
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• pp.41-45
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• 2022

The conventional communication method using mud flow pressure waves has a speed of 1-2 bps, so it takes a long time to communicate, making real-time control impossible. Although the sound wave communication method for improving the communication speed by 10 times or more has been commercialized, its use is limited due to its high price and there are not many application cases. In this study, the simulator corresponding to the facility was developed to develop performance similar to the actual test results. For simulating sound wave communication through a drill pipe, we proposed a governing equation that can simulate friction damping by mud and developed a numerical analysis model. The attenuation factor was corrected by comparing it with the attenuation rate of sound wave energy at the drilling site. The developed numerical analysis model was applied to the QPSK modulation type communication algorithm to confirm the excellent performance of the communication error rate of 0.04% in the ground. This is the communication performance under the condition that noise has not been mixed yet, and in order to apply it, the technology of reproducing the actual noise signal for mixing by securing the field noise data was established.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.1
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• pp.33-41
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• 2023

Recently, global warming has accelerated climate change, increased extreme weather phenomena, and increased the frequency and intensity of weather disasters, leading to increasing uncertainty about the power production of new and renewable energy that is sensitive to weather. In fact, it has been reported that a number of damage to hydroelectric power generation have occurred due to weather disasters. Therefore, using the hydroelectric power generation performance data of Chungju Dam, meteorological data of Chungju Meteorological Observatory, and operation data of Chungju Dam, this study investigated the effect of meteorological disasters on hydroelectric power generation through structural equation modeling considering the number and intensity of meteorological disasters per month. The results indicated that the increased drought occurrence affected the decreased hydroelectric power generation by about 38.3 %, however the increased hydroelectric power generation could not explained by the increased flood occurrence. In conclusion, an increased drought occurrence in future may significantly influence hydroelectric power generation.

• The Korean Journal of Mycology
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• v.51 no.3
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• pp.251-257
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• 2023

We isolated fungi from the rhizosphere of Fallopia sachalinensis in Dokdo islands. Morphological and molecular characters, based on the internal transcribed spacer (ITS), and partial large subunit (LSU) or partial beta-tubulin genes, were used to identify the isolated fungi. The results revealed the fungi isolated from the Fallopia rhizosphere to be Penicillium striatisporum and Gongronella sichuanensis. Given that these species have never previously been recorded in Korea, we have described the morphological and molecular characteristics of these fungi in this study.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.4
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• pp.201-209
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• 2016

Theoretical maximum methane yield of glucose at STP (1 atm, $0^{\circ}C$) is 0.35 L $CH_4/g$ COD. However, most researched actual methane yields of anaerobic digester (AD) on lab scale is lower than theoretical ones. A wide range of them have been reported according to experiments methods and types of organic matters. Recent year, a MET (Microbial electrochemical technology) is a promising technology for producing sustainable bio energies from AD via rapid degradation of high concentration organic wastes, VFAs (Volatile Fatty Acids), toxic materials and non-degradable organic matters with electrochemical reactions. In this study, methane yields of food waste leachate and sewage waste sludge were evaluated by using BMP (Biochemical Methane Potential) and continuous AD tests. As the results, methane production volume from the anaerobic digester equipped with MET (AD + MET) was higher than conventional AD in the ratio of 2 to 3 times. The actual methane yields from all experiments were lower than those of theoretical value of glucose. The methane yield, however, from the AD + MET occurred similar to the theoretical one. Moreover, biogas compositions of AD and AD + MET were similar. Consequently, methane production from anaerobic digester with MET increased from the result of higher organic removal efficiency, while, further researches should be required for investigating methane production mechanisms in the anaerobic digester with MET.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.369-377
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• 2013

This paper deals with the state of charge(SOC) and life cycle evaluation algorithm for lead-acid battery, which is essential factor of the electric vehicle(EV) and the stabilization of renewable energy in the smart grid. In order to perform the effective operation of the lead-acid battery, SOC and life cycle evaluation algorithm is required. Specific gravity with the change of electrolyte temperature inside battery case should be obtained to evaluate the SOC of lead-acid battery, however it is difficult to measure the electrolyte temperature of sealed type lead-acid battery. To overcome this problem, this paper proposes the equation of thermal transmission to compensate internal temperature of the lead-acid battery. Also, it is difficult to exactly evaluate the life cycle of battery, depending on the operation conditions of lead-acid battery such as charging and discharging state, self discharging rate and environmental issue. In order to solve the problem, this paper presents the concept for gravity accumulation of charge and discharge cycle, which is the value converted at $20^{\circ}C$. By using the proposed algorithm, this paper propose the test device based on the Labview software. The simulation results show that it is a practical tool for the maintenance of lead-acid battery in the field of industry.