• 한국태양에너지학회 논문집
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• 제40권4호
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• pp.23-33
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• 2020

The loss in photovoltaic power due to hailstorms has been highlighted as a major issue in the sustained growth of the PV power plant industry. This study investigates the safety of a solar module by conducting a numerical analysis of a hail test according to the IEC 61215 standard. Our study aims to elucidate the detailed behavior between the ice and solar modules and the micro-cracks forming on solar modules during hailstorms. To analyze the impact of hail, we used the ANSYS AUTODYN software to evaluate the impact characteristics on a solar module with different front glass thicknesses. The simulations show that a solar module with a glass thickness of 4.0 mm results in excellent durability against hail. The results indicate the feasibility of using simulations to analyze and predict micro-cracks on solar modules tailored to various conditions, which can be used to develop new solar modules.

• International Journal of Aeronautical and Space Sciences
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• 제14권2호
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• pp.193-199
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• 2013

This work investigates the orbital perturbations of the cubesats that lie on LEO due to Earth albedo. The motivation for this paper originated in the investigation of the orbital perturbations for closed- Earth pico-satellites due to the sunlight reflected by the Earth (the albedo). Having assumed that the Sun lies on the equator, the albedo irradiance is calculated using a numerical model in which irradiance depends on the geographical latitude, longitude and altitude of the satellite. However, in the present work the longitude dependency is disregarded. Albedo force and acceleration components are formulated using a detailed model in a geocentric equatorial system in which the Earth is an oblate spheroid. Lagrange planetary equations in its Gaussian form are used to analyze the orbital changes when $e{\neq}0$ and $i{\neq}0$. Based on the Earth's reflectivity data measured by NASA Total Ozone Mapping Spectrometer (TOMS project), the orbital perturbations are calculated for some cubesats. The outcome of the numerical test shows that the albedo force has a significant contribution on the orbital perturbations of the pico-satellite which can affect the satellite life time.

• 한방재활의학과학회지
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• 제23권3호
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• pp.15-26
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• 2013

Objectives The aim of this study was to investigate antimicrobial activity of Huanggeumjakyak- tang water extract against MRSA. Methods The antibacterial activities of Huanggeumjakyak-tang were evaluated against 3 strains of Methicillin-resistant Staphylococcus aureus (MRSA) and 1 standard Methicillinsusceptible S. aureus (MSSA) strain by using the disc diffusion method, minimal inhibitory concentrations (MICs) assay, colorimetric assay using MTT test, checkerboard dilution test and time-kill assay was performed under dark. Results The MIC (minimum inhibitory concentration) of Huanggeumjakyak-tang water extract against S. aureus strains ranged from 1,000 to $2,000{\mu}g/ml$. So we confirmed that it has a strong antibacterial effect. Also the combinations of Huanggeumjakyak-tang water extract and conventional antibiotics exhibited improved inhibition of MRSA with synergy effect. Conclusions The results obtained in this study suggest that Huanggeumjakyak-tang water extract showed antibacterial effect against MRSA, and it also showed reducing effect on the side-effect problems that are the major weak points of traditional antibiotics.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.144-145
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• 2006

ZnO is a promising material to make high efficiency violet or blue light emitting diodes (LEDs) for its large binding energy (60meV) and big bandgap. But the high quality p-type conduction of ZnO is a dilemma to achieve LEDs with it. In present study, we presented a reliable method to prepare ZnO thin films on (100)silicon substrates by RF magnetron sputtering in the mixture ambient of $N_2$ and $O_2$, accompanying with low pressure annealing in the sputtering chamber in $O_2$ at $600^{\circ}C$ and $800^{\circ}C$ respectively. X-ray diffraction and Hail effect with Van der Paul method were performed to test ZnO films. Seeback effect was also carried out to identify carrier types in ZnO films and showed the N-doped ZnO film annealed at $800^{\circ}C$ had achieved p-type conduction.

• International Journal of Computer Science & Network Security
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• 제22권2호
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• pp.232-240
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• 2022

To fulfill user expectations, the rapid evolution of software techniques and approaches has necessitated reliable and flawless software operations. Aging prediction in the software under operation is becoming a basic and unavoidable requirement for ensuring the systems' availability, reliability, and operations. In this paper, an improved evolutionary computing-driven extreme learning scheme (ECD-ELM) has been suggested for object-oriented software aging prediction. To perform aging prediction, we employed a variety of metrics, including program size, McCube complexity metrics, Halstead metrics, runtime failure event metrics, and some unique aging-related metrics (ARM). In our suggested paradigm, extracting OOP software metrics is done after pre-processing, which includes outlier detection and normalization. This technique improved our proposed system's ability to deal with instances with unbalanced biases and metrics. Further, different dimensional reduction and feature selection algorithms such as principal component analysis (PCA), linear discriminant analysis (LDA), and T-Test analysis have been applied. We have suggested a single hidden layer multi-feed forward neural network (SL-MFNN) based ELM, where an adaptive genetic algorithm (AGA) has been applied to estimate the weight and bias parameters for ELM learning. Unlike the traditional neural networks model, the implementation of GA-based ELM with LDA feature selection has outperformed other aging prediction approaches in terms of prediction accuracy, precision, recall, and F-measure. The results affirm that the implementation of outlier detection, normalization of imbalanced metrics, LDA-based feature selection, and GA-based ELM can be the reliable solution for object-oriented software aging prediction.

• 비파괴검사학회지
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• 제37권2호
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• pp.91-98
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• 2017

Recently, composite materials have been mainly used in the main wings, ailerons, and fuselages of aircraft and rotor blades of helicopters. Composite materials used in rapid moving structures are subject to impact by hail, lightning, and bird strike. Such an impact can destroy fiber tissues in the composite materials as well as deform the composite materials, resulting in various problems such as weakened rigidity of the composite structure and penetration of water into tiny cracks. In this study, experiments were conducted using a 2 kW halogen lamp which is most frequently used as a light source, a 2 kW near-infrared lamp, which is used for heating to a high temperature, and a 6 kW xenon flash lamp which emits a large amount of energy for a moment. CFRP composite sandwich panels using Nomex honeycomb core were used as the specimens. Experiments were carried out under impact damages of 1, 4 and 8 J. It was found that the detection of defects was fast when the xenon flash lamp was used. The detection of damaged regions was excellent when the halogen lamp was used. Furthermore, the near-infrared lamp is an effective technology for showing the surface of a test object.

• 한국콘텐츠학회논문지
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• 제21권11호
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• pp.490-502
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• 2021

원예시설 농가들은 시설에서 발생할 수 있는 위험에 대비하여 농작물재해보험 원예시설 담보의 보험상품을 가입한다. 상품이 담보하는 태풍, 우박, 동상해, 호우, 강풍피해 등의 자연재해에 대비하기 위하여 보험에 가입하는 것이다. 농가들이 위와 같은 자연재해 등으로 부터 인지할 수 있는, 즉 주어진 상황의 위험성에 대한 주관적인 지각인 위험지각이 원예시설 농가로 하여금 원예시설 보험상품 구매의도에 미치는 영향을 알아보고자 제주지역의 원예시설 농가 소유주를 대상으로 위험지각과 보험구매의도에 대해 분석하였다. 농장규모, 보험가입 여부와 위험지각의 영향관계 규명을 위해 t-test를 시행하였고 주관적 인식, 준거집단, 미디어 노출, 보상이해도 등 개인적 특성과 행동요인이 위험인식에 미치는 영향을 검증하기 위해 다중회귀분석을 하였다. 그리고 위험지각과 보험구매의도의 영향관계에서 개인적 특성 및 행동요인의 매개역할을 확인하기 위해 Baron & Kenny의 3단계 회귀분석을 실시하였다. 연구결과 농장규모에 따른 차이는 없으나 보험가입자가 미가입자에 비해 위험지각 정도가 더 높은 것으로 분석되었고 보상이해도가 가장 큰 영향력을 가지며 주관적 지식의 영향력이 가장 작은 것으로 확인되었다. 또한 이 네 가지 요인은 위험지각과 보험구매의도의 영향관계에 매개효과를 갖는 것으로 검증되었다. 이러한 결과는 원예시설 보험상품 개발과 마케팅 활동에 실무적인 도움을 제공할 수 있을 것으로 기대된다.