• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.1
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• pp.53-62
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• 2023

Due to the recent increase in new and renewable energy, gas turbine generators start and stop every day to supply high-quality power, and accordingly, the life span of high-temperature parts is shortened and the failure of combustion chamber temperature sensors increases. Therefore, in this study, we proposed a fuzzy logic-based failure diagnosis algorithm that can accurately diagnose and systematically detect the failure of the sensor when the dual temperature sensor used for gas turbine control fails, and to confirm the usefulness of the proposed algorithm We tried to confirm the usefulness of the proposed algorithm by performing various simulations under the matlab/simulink environment.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.4
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• pp.31-41
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• 2022

As the environmental impacts of fossil fuel energy sources increase, the South Korean government has tried to change non-environmental-friendly enery sources to environmental-friendly energy sources in order to mitigate environmental effects, which lead to global warming and air pollution. With both a limited budget and limited time, it is essential to accurately evaluate the economic and environmental effects of renewable energy projects for the efficient and effective operation of renewable energy plants. Although the traditional economic evaluation methods are not ideal for evaluating the economic impacts of renewable energy projects, they can still be used for this purpose. Renewable energy projects involve many risks due to various uncertainties. For this reason, this study utilizes a real option method, the Geske compound model, to evaluate the renewable energy projects on Jeju Island in terms of economic and environmental values. This study has developed an economic evaluation model based on the Geske compound model to investigate the influences of flexibility and uncertainty factors on the evaluation process. This study further conducts a sensitivity analysis to examine how two uncertainty factors (namely, investment cost and wind energy production) influence the economic and environmental value of renewable energy projects.

• Korea Trade Review
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• v.41 no.2
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• pp.185-202
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• 2016

Interests in renewable energy have been increasing with low-carbon policy and concerns about radioactivity. And solar energy is receiving attention as the most realistic energy in the industry. Demand for solar energy was started in Germany and European countries, and further expanding to other countries. And Korea became one of the high technology level countries in that industry. So, systematic analysis is needed for trading fact and overseas expansion of Korea's photovoltaic energy together with increased demand in the world. In this paper, we analyzed panel data for 25 years, from 1990 to 2014 from 11 countries that have track record with Korea's PV product. It is conducted based on Gravity model and matched with general report for Korean PV industry. But it shows different result for other factors.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.845-848
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• 2021

최근 화석연료의 급격한 사용에 따른 자원고갈이나 환경오염과 같은 문제들이 심각해짐에 따라 화석연료를 대체할 수 있는 신재생에너지에 대한 관심이 높아지고 있다. 태양광 에너지는 다른 에너지원에 비해 고갈의 우려가 없고, 부지 선정의 제약이 크지 않아 수요가 증가하고 있다. 태양광 발전 시스템에서 생산된 전력을 효과적으로 사용하기 위해서는 태양광 발전량에 대한 정확한 예측 모델이 필요하다. 이를 위한 다양한 딥러닝 기반의 예측 모델들이 제안되었지만, 이러한 모델들은 모델 내부에서 일어나는 의사결정 과정을 들여다보기가 어렵다. 의사결정에 대한 설명이 없다면 예측 모델의 결과를 완전히 신뢰하고 사용하는 데 제약이 따른다. 이런 문제를 위해서 최근 주목을 받는 설명 가능한 인공지능 기술을 사용한다면, 예측 모델의 결과 도출에 대한 해석을 제공할 수 있어 모델의 신뢰성을 확보할 수 있을 뿐만 아니라 모델의 성능 향상을 기대할 수도 있다. 이에 본 논문에서는 Long Short-Term Memory(LSTM)을 사용하여 모델을 구성하고, 모델에서 어떻게 예측값이 도출되었는지를 SHapley Additive exPlanation(SHAP)을 통하여 설명하는 태양광 발전량 예측 기법을 제안한다.

• Journal of Wind Energy
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• v.4 no.1
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• pp.39-45
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• 2013

Massive offshore wind projects of have recently been driven in full gear on the Western Offshore of Korea including the 2.5 GW West-Southern Offshore Wind Project of the Ministry of Trade, Industry and Energy, and the 5 GW Offshore Wind Project of the Jeollanamdo Provincial Government. On this timely occasion, this study performed a general wind resource assessment on the Western Offshore by using the MERRA reanalysis data of temporal-spatial resolution and accuracy greatly improved comparing to conventional reanalysis data. It is hard to consider that wind resources on the Western Sea are excellent, since analysis results indicated the average wind speed of 6.29 ± 0.39 m/s at 50 m above sea level, and average wind power density of 307 ± 53 W/m². Therefore, it is considered that activities shall be performed for guarantee economic profits from factor other than wind resources when developing an offshore wind project on the Western Offshore.

• Journal of Aerospace System Engineering
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• v.17 no.6
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• pp.94-99
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• 2023

Recently, renewable energy has been widely used as a source of wind energy and solar energy due to the shortage of fossil fuels and environmental problems. Against this backdrop, wind energy is emerging as an important energy source, and the wind power market is showing rapid growth worldwide. In this study, a high-efficiency wind turbine blade was designed with an integrated blade aerodynamic design for prior research on separate blades. The blade airfoil was applied as NACA 4418, and it was verified by comparing it with the analysis results to evaluate the newly designed blade.

• Convergence Security Journal
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• v.23 no.5
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• pp.73-79
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• 2023

Cyber threats are evolving and becoming more sophisticated with the development of new technologies, and consequently the number of service failures caused by DDoS attacks are continually increasing. Recently, DDoS attacks have numerous types of service failures by applying a large amount of traffic to the domain address of a specific service or server. In this paper, after generating the data of the Syn Flooding attack, which is the representative attack type of bandwidth exhaustion attack, the data were compared and analyzed using Random Forest, Decision Tree, Multi-Layer Perceptron, and KNN algorithms for the effective detection of attacks, and the optimal algorithm was derived. Based on this result, it will be useful to use as a technique for the detection policy of Syn Flooding attacks.

• Journal of Plant Biotechnology
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• v.44 no.4
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• pp.401-408
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• 2017

Herein, we report the meristem-tip culture from dormant buds of grape 'Kyoho' single-infected with Grapevine fleck virus (GFkV), which is phloem-limited and transmitted by graft inoculation. We produced GFkV-free shoots without thermo- or chemotherapy using meristem-tip explants approximately 0.3 mm (73 explants) and 0.8 mm long (five explants) including shoot apical meristem, 2-5 leaf primordia, and 1-4 uncommitted primordia from dormant buds of the infected woody cuttings (stored at $4^{\circ}C$). Explants were cultured on Murashige and Skoog (MS) medium supplemented with 3% sucrose, 3.0 mg/L benzyladenine (BA) and 0.1 mg/L indole-3-butyric acid (IBA). After 16 weeks of culture, shoot (10-mm long) regeneration frequency achieved from 0.3-mm explants was 4.1% and that obtained from 0.8-mm explants was 40.0%. Virus-free efficiency (expressed as the percentage of RT-PCR negative shoots regenerated) from 0.3- and 0.8-mm explants was 100% and 50%, respectively. Following in vitro multiplication, RT-PCR assays revealed identical results to assays of the first regenerated shoots. Our new methodological approach could be applied for eliminating other viruses in grapevines, as well as for producing virus-free plants in many other deciduous tree species, including fruit trees.

• The Korean Journal of Mycology
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• v.13 no.3
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• pp.169-177
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• 1985

The studies were carried out to obtain the basic data for maximizing the protoplast yields from the mycelia of P. ostreatus and P. sajor-caju. Some factors affecting the regeneration of the protoplast of both species and the productivity of their reversion were also examined. The maximum yields of protoplasts were obtained from four days cultured mycelia of both species on cellophan membrane placed on the surface of PSA or MCM media in a petri dish. The optimal concentration of lytic enzyme Novozym 234 for protoplast releasing was 5 mg per ml of 0.5 M phosphate buffer solution with 0.6 M sucrose or 0.6 M $MgSO_4$ at pH 6.0. The greatest number of protoplasts was released 3 hours after incubation of the mycelia of P. ostreatus and after 4 hours for the P. sajor-caju in the lytic enzyme solution. Among the osmotic stabilizer solutions tested 0.6 M sucrose and 0.6 M KCl showed the best regeneration rates of the protoplasts of both species. When 0.75 % agar solution was over-layed on the regeneration media immediately after inoculation of the protoplast the regeneration rates were greatly enhanced. The ampicillin added to the agar solution prevented bacteria from infection. The reverted isolates produced the sporophores and basidial spores just like their parents without any mutations when they were cultivated in a broad mouth bottle with sawdust substrates.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1123-1131
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• 2001

The sintering behaviors of the renewed $Al_2$O$_3$ceramics were investigated as functions of the addition amount and particle size of recycling $Al_2$O$_3$powder, such as crushed powder of structural $Al_2$O$_3$ceramics and waste $Al_2$O$_3$adsorbent, were investigated. Pure $Al_2$O$_3$sample was fabricated by sintered at 1,$650^{\circ}C$ for 5h and it was crushed into powder (-40${\mu}{\textrm}{m}$and +40${\mu}{\textrm}{m}$ in particle size) by thermal shock treatment and crushing. Then, 10~50wt% of crushed $Al_2$O$_3$powder and waste $Al_2$O$_3$adsorbent were mixed with pure $Al_2$O$_3$powder and were subjected to re-sintering to renewed $Al_2$O$_3$sample. The density and the 3-point bending strength increased with increasing the sintering temperature without regard to the addition amount and particle size of recycling $Al_2$O$_3$powder, and that of the samples at the same sintering temperature decreased with increasing the addition amount and particle size of recycling $Al_2$O$_3$powder. Samples over 200 Mpa of 3-point bending strength were obtained by mixing ~30wt% of crushed $Al_2$O$_3$powder(-40${\mu}{\textrm}{m}$), ~20wt% of crushed $Al_2$O$_3$powder (+40${\mu}{\textrm}{m}$) and 10wt% of waste $Al_2$O$_3$adsorbent. 5~20wt% of waste glass powder containing renewed $Al_2$O$_3$samples for densification were fabricated by sintered at 1200~1$650^{\circ}C$ for 5h. The temperature of maximum density and 3-point bending strength decreased with increasing the addition amount of waste glass powder, however, these samples at above 140$0^{\circ}C$ showed lower density and bending strength than renewed $Al_2$O$_3$samples. The addition of waste glass powder did not improved the densification of renewed $Al_2$O$_3$sample.