• 한국신뢰성학회지:신뢰성응용연구
• /
• 제16권4호
• /
• pp.338-346
• /
• 2016

Purpose: The purpose of this research is to improve the reliability of the composite material blades used for the wind power generator, by applying the phased array ultrasonic testing technique out of the many nondestructive test into the blades. Method: The wind power generation composite blades are used, as a case study, in order to evaluate the reliability of the phased array ultrasonic testing technique. Defects that are most likely occurred in the field are injected into the different locations of the three different types of artificial test pieces and then phased array ultrasonic testing technique are applied to evaluate the reliability of its effectiveness. Result: As a result of the analysis of the defect signals by applying the A scan and B scan simultaneously, depth and width of the defect could be obtained. An area of defect was proportional to the amount of energy by color in B scan image. The larger amount of energy, reflected amount of energy was appeared in the order of red, orange, yellow, blue color. Conclusion: The most reliable testing method to detect the defect in composite blades for wind power generation is considered to be the combination of the other destructive testing technique with the phased array ultrasonic testing since the PAUT alone could not detect all range of the defects in the blades.

• KIEAE Journal
• /
• 제14권1호
• /
• pp.121-129
• /
• 2014

As time passes, the aging of the plant building, the building's energy performance degradation than the initial plan does not express a situation could arise. This year, the certification of buildings certified in 2009 has expired for measures such as the situation required. In this study, management of national and international green building certification and re-certification was compared in two ways. First, the evaluation of green building certification system management assessments were compared. Second, the green building certification system for the re-certification analysis. As a result, G-SEED was not reflected life-cycle of building in management assessment and the commissioning of G-SEED is the UK and the U.S and other concepts of evaluation. In addition, the re-certification system is insufficient about substantial energy consumption of buildings. In this study, the revised the management assessments in conjunction with the re-certification system to manage the building is proposed to improve. In addition, the current evaluation of the existing building certification "existing building" and "building the first certified" as it is more efficient to separate the information into assessment was judged. Green building certification system to meet the purpose of management and operation, and disposal phases of the building to promote energy conservation and sustainability in order to the management a systematic and detailed evaluation and re-certification system developed for the revision of the specific items required and future research want to continue.

• 한국수소및신에너지학회논문집
• /
• 제15권3호
• /
• pp.235-243
• /
• 2004

A number of potential applications of aluminum foams are being identified and renewed interest in these engineering materials is also reflected by several current research projects. One of the key issues for industrial exploitation of aluminum foams is the development of cost-effective manufacturing strategies facilitating, preferably, net shape production of foams with controlled porosity and cell size, and minimized structural imperfection. Especially, melt route to aluminum foam production based on the foaming agents offer attraction of low cost and the potential for good microstructure. The present paper is focused mainly on foaming agents of melt-foam aluminum such as $TiH_2$ or $TiH_2-Al$ mixture. For the purpose of economical manufacturing, we are proposed to hydrogen induced mechanical alloying (HIMA) process. Thermo-physical properties of particles synthesized are compared with conventional methods. Specimens synthesized are characterized by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), thermo- gravimetry-differential scanning calorymetry (TG-DSC), pressure-composition-isotherm. (PCI).

• Steel and Composite Structures
• /
• 제35권3호
• /
• pp.439-447
• /
• 2020

This paper presents two sets of full three-dimensional thermoelastic finite element analyses of superimposed thermo-mechanically loaded Spar Wingskin Joints made with laminated Graphite Fiber Reinforced Plastic composites. The study emphasizes the influence of residual thermal stresses and material anisotropy on the inter-laminar delamination behavior of the joint structure. The delamination has been pre-embedded at the most likely location, i.e., in resin layer between the top and next ply of the fiber reinforced plastic laminated wingskin and near the spar overlap end. Multi-Point Constraint finite elements have been made use of at the vicinity of the delamination fronts. This helps in simulating the growth of the embedded delamination at both ends. The inter-laminar thermoelastic peel and shear stresses responsible for causing delamination damage due to a combined thermal and a static loading have been evaluated. Strain energy release rate components corresponding to the Mode I (opening), Mode II (sliding) and Mode III (tearing) of delamination are determined using the principle of Virtual Crack Closure Technique. These are seen to be different and non-self-similar at the two fronts of the embedded delamination. Residual stresses developed due to the thermoelastic anisotropy of the laminae are found to strongly influence the delamination onset and propagation characteristics, which have been reflected by the asymmetries in the nature of energy release rate plots and their significant variation along the delamination front.

• Asian-Australasian Journal of Animal Sciences
• /
• 제13권7호
• /
• pp.995-1002
• /
• 2000

To evaluate energy efficiency and partition of nutrients, 32 piglets were weaned at 14 d of age and individually fed diets containing 15% fat from coconut oil (CO, medium chain saturated), high oleate sunflower oil (HOSO, n-9 series), soybean oil (SO, n-6 series), or linseed oil plus fish oil, (LF, n-3 series). After 4 weeks, the subjects were sacrificed to evaluate empty body composition and apparent ileal digestibility with the slaughter method. No statistical effect of dietary fat sources on growth was observed. The digestibility of fat from the coconut oil diet was higher than fats from the diets containing high levels of unsaturated fatty acids. The efficiency of use of metabolizable energy for growth averaged 63% and was not affected by the diet. Dietary fat composition was reflected strongly in backfat. Total body neutral and polar fatty acids were influenced too. For the whole body phospholipid fraction the ratio of n-6 to n-3 and the double bond index were 4.3, 5.8, 7.2, 0.78 and 69, 87, 89, 87 for CO, HOSO, SO, and LF respectively. These results show that for the coconut oil diet the degree of unsaturation of phospholipids in the body was lower and that, in the other diets, it did not differ, but double bond index was maintained with different n-6 to n-3 ratios in carcass fat. On the whole the data on body fat composition indicate that the dietary fat tended to be deposited in similar quantity in the body, whatever was the dietary fatty acid profile.

• 대한의용생체공학회:의공학회지
• /
• 제30권6호
• /
• pp.489-494
• /
• 2009

In this study, we fabricated a plastic optical fiber based sensor which can monitor the respiration of a patient. The circumference changes of the abdomen were measured using a mirror, a light source and optical detectors because the circumferences of the abdomen could be varied with respiration. The intensity of the reflected lights were measured according to the changes of distance between mirror and plastic optical fiber connected to a light source and a photodiode-amplifier system using a Y-coupler. The respiration signals of fiber-optic sensor system were compared with those of the respiratory and temperature transducers of the $BIOPAC^{(R)}$ system. It is expected that a fiber-optic respiration sensor could be developed for real time respiration monitoring during MRI procedure based on this study.

• 한국환경과학회지
• /
• 제24권6호
• /
• pp.819-826
• /
• 2015

This study measured temperatures and albedos of urban surfaces for different colors and materials during summer, and calculated the energy budget over different urban surfaces to find out the thermal performance affecting the heat built-up. The study selected six surface colors and 13 materials common in urban landscape. Their surface temperatures (Ts) and albedos were measured at a given time interval in the daytime from June to August. Average Ts over summer season for asphalt-colored brick was $4.0^{\circ}C$ higher than that for light red-colored one and $9.7^{\circ}C$ higher than that for white-colored one. The Ts for artificial surface materials of asphalt paving, brown brick wall, and green concrete wall was $6.0^{\circ}C$ higher than that for natural and semi-natural ones of grass, grassy block, and planted concrete wall. There was the greatest difference of $16.3^{\circ}C$ at midafternoon in the Ts between asphalt paving and planted concrete wall. Average albedo over summer season of surface materials ranged from 0.08 for asphalt paving to 0.67 for white concrete wall. This difference in the albedo was associated with a maximum of $15.7^{\circ}C$ difference at midafternoon in the Ts. Increasing the albedo by 0.1 (from 0.22 to 0.32) reduced the Ts by about $1.3^{\circ}C$. Average storage heat at midday by natural and semi-natural surfaces of grass and grassy block was about 10% lower than that by artificial ones of asphalt, light-red brick, and concrete. Reflected radiation, which ultimately contributes to heating the urban atmosphere, was 3.7 times greater for light-red brick and concrete surfaces than for asphalt surface. Thus, surfaces with in-between tone and color are more effective than dark- or white-colored ones, and natural or semi-natural surfaces are much greater than artificial ones in improving the urban thermal environment. This study provides new information on correlation between Ts and air temperature, relationship between albedo and Ts, and the energy budget.

• Journal of Radiation Protection and Research
• /
• 제41권4호
• /
• pp.384-388
• /
• 2016

Background: For a verification of newly-developed neutron absorbers, one of guidelines on the qualification and acceptance of neutron absorbers is the neutron attenuation test. However, this approach can cause a problem for the qualifications that it cannot distinguish how the neutron attenuates from materials. Materials and Methods: In this study, an estimation method of neutron absorption performances for materials is proposed to detect both direct penetration and back-scattering neutrons. For the verification of the proposed method, MCNP simulations with the experimental system designed in this study were pursued using the polyethylene, iron, normal glass and the vitrified form. Results and Discussion: The results show that it can easily test neutron absorption ability using single absorber model. Also, from simulation results of single absorber and double absorbers model, it is verified that the proposed method can evaluate not only the direct thermal neutrons passing through materials, but also the scattered neutrons reflected to the materials. Therefore, the neutron absorption performances can be accurately estimated using the proposed method comparing with the conventional neutron attenuation test. Conclusion: It is expected that the proposed method can contribute to increase the reliability of the performance of neutron absorbers.

• 에너지공학
• /
• 제26권1호
• /
• pp.1-8
• /
• 2017

에틸렌글리콜법을 활용하여 국내 순환유동층보일러형 발전소에서 발생되는 석탄회의 물리화학적 특성 및 Free CaO 평가를 수행하였다. 물리화학적 특성결과, 각 발전사마다 많은 CaO 함량 차이를 나타내었는데, 이는 황산화물 배출농도 규제 차이 및 보일러 제작사가 다른 발전소의 운전특성이 복합적으로 반영된 것으로 판단된다. Free CaO의 함량은, 비산재는 1.96 ~ 10.78 %, 바닥재는 0.07 ~ 4.24%로 비산재가 바닥재보다 높게 나타났으며, 원시료의 CaO 함량 이외에 입도 분포에 따라서도 크게 변화되는 것으로 확인되었다.

• 자원ㆍ환경경제연구
• /
• 제30권3호
• /
• pp.435-469
• /
• 2021

본 연구에서는 패널 공간더빈모형을 활용하여 유럽연합 회원국 26개 국가의 전력수출입 결정요인을 밝히는 것을 주요 목적으로 하며, 특히 전원별 발전량을 중심으로 설명하고자 한다. 이때 공간더빈모형을 활용함에 있어 단순히 인접기준 혹은 거리에 의해 가중치를 부여하는 방식이 아닌 전력 계통이 연계된 국가 간의 교역 비중을 기준으로 공간가중치 행렬을 구성하고자 한다. 또한 유럽 국가들의 전력계통은 직간접적으로 연결되어 지리적으로 멀리 떨어진 국가들 사이의 상호작용이 가능하므로, 이를 가중치행렬에 반영한다. 이를 바탕으로 분석한 결과, 원자력발전은 수출에는 양의 효과, 수입에는 음의 효과를 미치며 풍력·태양광 발전량의 증가는 전력의 계통 불안정성을 높여 수출과 수입에 모두 양의 효과를 미치는 것으로 분석되었다. 현재 국내의 지리적 여건상 타국과의 전력교역은 어려운 실정이다. 따라서 본 연구의 결과는 국내 에너지믹스 정책에 있어 시사하는 바가 있으며, 이전에 사용되지 않던 방식의 가중치행렬을 이용한 패널 공간더빈모형을 통해 전력수출입 요인을 분석했다는 데 의의가 있다.