• Title/Summary/Keyword: Blade joint s

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Investigation on Research Trends for Separation of Wind Turbine Blade (풍력 블레이드 분리를 위한 연구 동향 분석)

  • Wooseong Jeong;Hyunbumm Park
    • Journal of Wind Energy
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    • v.14 no.4
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    • pp.68-74
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    • 2023
  • Research is being actively conducted to increase energy production by increasing the length of wind turbine blades. However, it is difficult to manufacture and transport large-scale blades. Various studies are being conducted on the concept of separate wind turbine blades considering transportation methods and maintenance. In this study, various methods of dividing blades and assembling the divided blades were reviewed. The position of the division when the blades are divided was analyzed.

Aerodynamic and Structural Design for Medium Size Horizontal Axis Wind Turbine Rotor Blade with Composite Material (복합재를 이용한 수평축 풍력터빈 회전 날개의 공력 및 구조설계에 관한 연구)

  • 공창덕;방조혁;오동우;김기범;김학봉
    • Journal of the Korean Society of Propulsion Engineers
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    • v.1 no.2
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    • pp.12-21
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    • 1997
  • Nowadays, non-pollution energy sources have been strongly needed because of the exhaustion of fossil fuels and serious environmental problems. Because wind energy can be enormously obtained from natural atmosphere, this type of energy has lots of advantages in a economic and pollution point of view. This study has established the aerodynamic and structural design procedure of the rotor blade with an appropriate aerodynamic performance and structural strength for the 500㎾ medium class wind turbine system. The aerodynamic configuration of the rotor blade was determined by considering the wind condition in the typical local operation region, and based on this configuration aerodynamic performance analysis was performed. The rotor blade has the shell-spar structure based on glass/epoxy composite material and is composed of shank including metal joint parts and blade. Structural design was done by the developed design program in this study and structural analysis, for instance stress analysis, mode analysis and fatigue life estimation, was performed by the finite element method. As a result, a medium scale wind turbine rotor blade with starting characteristics of 4m/s wind speed, rated power of 500㎾ at 12m/s wind speed and over 20 years fatigue life has been designed.

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Stress Analysis of the Blade Joint for a Small Wind Turbine (소형풍력터빈 블레이드 체결부의 응력해석)

  • Kim, Deok-Su;Jung, Won-Young;Jung, Jin-Tai
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.1
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    • pp.117-124
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    • 2012
  • In this paper, an analysis of the joint that transmits power from the blades to the generator is performed using the FEM (finite element method). The mode shapes and natural frequencies were extracted using experimental modal analysis in order to establish the FEM model. Then, the model was verified by comparing the mode shapes and natural frequencies to those obtained from the ANSYS modal analysis. Dynamic stress analysis was performed at the rated and limited wind speeds considering the wind load and gravity.

Structural Design and Experimental Investigation of A Medium Scale Composite Wind Turbine Blade Considering Fatigue Life (피로 수명을 고려한 중형 복합재 풍력터빈 블레이드의 구조설계 및 실험 평가)

  • Gong, Chang Deok;Bang, Jo Hyeok
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.3
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    • pp.23-30
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    • 2003
  • In this study, the various load cases by specified by the IEC61400-1 international specification and GL Regulations for the wind energy conversion system were considered, and a specific composite structure configuration which can effectively endure various loads was proposed. In order to evaluate the structure, the structural analysis for the composite wind turbine blade was performed using the finite element method(FEM). In the structural design, the acceptable configuration of blade structure was determined through the parametric studies, and the most dominant design parameters were confirmed. In the stress analysis using the FEM, it was confirmed that the blade structure was safe and stable for all the considerd load cases. Moreover the safety of the blade root joint with insert bolts, newly devised in this study, was checked against the design loads and also the fatigue loads. The fatigue life for operating more than 20 years was estimated by using the well-known S-N linear damage rule, the load spectrum and Spera's empirical equations. The full-scale static test was performed under the simulated aerodynamic loads. from the experimental results, it was found that the designed blade had the structural integrity. Furthermore the measured results were agreed with the analytical results such as deflections, strains, the mass and the radial center of gravity. The studied blade was successfully certified by an international institute, GL, of Germany.

A Study on Mechanical Shearing Process for Tailored Blank Welding (테일러드블랭크 용접을 위한 전단 공정 연구)

  • 유병길;이경돈
    • Journal of Welding and Joining
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    • v.17 no.2
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    • pp.66-75
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    • 1999
  • Weld bead quality in tailored blank(TB) is critically affected by edge preparation of sheets. The edge quality of prepared sheets for TB can be classified into straightness and the cross section quality of sheared plane such as a ratio of shear face, shear plane angle, etc. In order to have a good edg quality for butt-welding sheets, precision shearing will be recommended. In this paper, the feasibility of a conventional mechanical shearing as the edge preparation for tailored blanks is studyied. It reveals that fine shearing may not be the unique solution as it is generally accepted. To obtain the good shearing condition with a conventional mechanical shearing, experiments were carried out using Tahuchi method. The major parameters affecting a sheared contour are the clearance between upper blade and lower blade, and shear angle. The optimal shearing condition yields a very good straightness along the entire length of the cut, which gives a butt joint gap less than 10% of the base material thickness. The good cross section of sheared plane is also achieved in the optimal shearing condition such as a ratio of the shear face above 65%, a cross section's shear plane angle above 85%, little burr, which is providing finally good weld beads.

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A Study of Tube Angle and Patient's Rotation Angle in Scapular Y View (어깨뼈 후전사방향촬영에서 Tube 각도와 환자의 회전각도 관한 연구)

  • Ahn, ByeoungJu;Lee, JunHaeng
    • Journal of the Korean Society of Radiology
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    • v.7 no.4
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    • pp.271-275
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    • 2013
  • Shoulder bone scan everyday life, sports activities at the side of the shoulder joint, or applying strong force in the lateral occurs. Mainly on upper arm abduction, temple, other rotational dislocation of the shoulder joint gahaejyeo as useful for observing the presence or absence of lesions is used. Shoulder PA oblique projection prevent distortion of the image due to the angle and the most useful diagnostic radiological investigate shooting angle. Shoulder blade body and the acromion and coracoid process Y-view is formed characters. $10^{\circ}$ angle between the shoulder blades and the acromion is the obstruction. $20^{\circ}{\sim}25^{\circ}$ to the Y-view of the humerus head looks superimposed, the position of the shoulder joint and seemed appropriate. $35^{\circ}$ of the humerus head superimposed on the Y-view, but above the humerus head and shoulder joints were distorted. When $45^{\circ}$ elevation observed on the side of the best has come Y-view also acromion and coracoid process is finished.

Evaluation of Fatigue Damage for Wind Turbine Blades Using Acoustic Emission (음향방출(AE)을 이용한 풍력 블레이드의 피로손상 평가)

  • Jee, Hyun-Sup;Ju, No-Hoe;So, Cheal Ho;Lee, Jong-Kyu
    • Journal of the Korean Society for Nondestructive Testing
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    • v.35 no.3
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    • pp.179-184
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    • 2015
  • In this study, the flap fatigue test of a 48 m long wind turbine blade was performed for 1 million cycles to evaluate the characteristics of acoustic emission signals generated from fatigue damage of the wind blades. As the number of hits and total energy continued to increase during the first 0.6 million cycles, blade damage was constant. The rise-time result showed that the major aspects of damage were initiation and propagation of matrix cracks. In addition, the signal analysis of each channel showed that the most seriously damaged sections were the joint between the skin and spar, 20 m from the connection, and the spot of actual damage was observable by visual inspection. It turned out that the event source location was related to the change in each channel's total energy. It is expected that these findings will be useful for the optimal design of wind turbine blades.

Friction Welding Optimization of Hot Die Punch Materials and Its AE Evaluation (열간 금형재의 마찰용접 최적화와 AE평가)

  • Oh, S.K.;Kong, Y.S.;Park, I.D.;Yoo, I.J.
    • Journal of Power System Engineering
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    • v.4 no.4
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    • pp.54-58
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    • 2000
  • The complete joining method for dissimilar hot die punch materials and its real-time evaluation method are not available at present. Brazing method has been used for joining them, but it is known that the welded joint by the brazing has the lower bonding efficiency and reliability than the diffusion welding. The friction welding with a diffusion mechanism in bonding was applied in this study. So, this work was carried out to determine the optimal friction welding conditions and to analyze mechanical properties of friction welded joints of hot die punch materials (STD61 for the blade part of hot die punch) to alloy steel (SCM440 for the shank part of hot die punch) such as plunger. In addition, acoustic emission test was carried out during friction welding to evaluate the weld quality.

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The Effects of Radix aconiti on the Contraction of Rat's Spinal Cord Injury (부자(附子)의 경구투여(經口投與)가 RAT의 척수손상(脊髓損傷)에 미치는 영향(影響) 및 비교(比較))

  • Lee Geon-Mok;Kim Kyung-Sik;Lee Kang-Chang
    • Journal of Acupuncture Research
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    • v.15 no.2
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    • pp.105-116
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    • 1998
  • Purpose In this study, We observed the recovery process in the ability to move in the hind limbs of the rats whose spinal cord injuries were treated by Radix acouniti(RA). The purpose of this study is to see the effects of Radix acouniti(RA) water extract on the contraction of rat's spinal cord injury. Procedure First, the rats were subjected to hemisectional spinal cord injuries by a scalpel blade. Those rats, then, were divided into three groups: Sham operated rats group and the experimental group, which received the Radix acouniti(RA) water extract, and the control group, which had no treatment. Their recovery in the ability to walk was observed by the Open Field Test (OFT) for 14 days after the injuries. Method The OFT was applied at four points: the hip, knee, ankle joint, and the tail. Each joint was given a movement rating of from 0 to 3, depending on the amount of movement. A movement rating of 0 designates no movement, a 1 designates slight movement, a 2 designates increased movement, and a 3 designates active movement. Slight movement is defined as a joint displaying less than or equal to 30% of that joint range, increased movement is displaying less than or equal to 60% of that joint's range, and active movement is greater than or equal to 90% of that joint's range. Tail movement is also graded on a scale of 0 to 3. A rating of 0 indicates that the tail is down 100% of the time, one of 1 indicates that the tail is down more than 10%, one of 2 shows that the tail is down less than 50% but more than 10% of the time, and one of 3 shows that the tail is down less than 10% of the time. All four ratings were added together and then averaged to arrive at a single score. Results The sham group which did not go through spinal cord injuries showed near normal results on all 3 joints and tail from right after the operation, which one would expect. The RA oral application group showed more effective recovery of movememt function than the control group around 4 days after the spinal cord injuries. However, after 14 days, both groups displayed almost the same degree of movement recovery. The results of this study are summarized as follows: 1. After 14days the spinal cord injuries, movement was recovered in sham operated group, control group, and experimented group in the hip, the knee, the tail and then the ankle of rats, in that order. 2. Around 7 days after the spinal cord injuries, the experimental group proved the effectiveness of the therapy in terms of movement recovery. 3. The level of ALT, ALP, AST in RA treated group was slightly increased. 4. The level of BUN and creatinine in RA treated group was slightly increased. The above results indicate that RA therapy at an early stage can bring about better movement recovery in patients with spinal cord injuries from traffic accidents or industrial disasters. But there is apparent side effect of RA on clinical, therefore the study on this should be continued.

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Evaluation of Microbiological Safety of Knives and Cutting Boards in Child Care Centers (보육시설과 지역아동센터 칼과 도마의 미생물학적 안전성 평가)

  • Kang, Ju-Yeong;Park, Eun-Ji;Lee, Han-Cheol;Park, Min-Ji;Oh, Do-Gyung;Kim, Chan-Yeong;Jeong, Eun-Sun;Lee, Young-Ju;Kim, Jung-Beom
    • The Korean Journal of Food And Nutrition
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    • v.33 no.6
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    • pp.702-709
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    • 2020
  • The purpose of this study was to evaluate microbiological contamination of knives and cutting boards in child-care centers. Materials used in this study were swabbed of cutting boards and knives (blade, handle of knife, and joint of handle and blade) in 129 child-care centers. Mean values of total aerobic bacteria of swabs of knives and cutting boards were 1.7±0.7 log cfu/100 ㎠ and 1.7±0.9 log cfu/100 ㎠, respectively. Contamination levels of coliform bacteria from knives and cutting boards were 1.5±0.6 log cfu/100 ㎠ and 1.7±0.8 log cfu/100 ㎠, respectively. Comparing microbiological contamination levels of knives and cutting boards according to type and size of child-care centers, there was no significant difference. Bacillus cereus was detected in knife handles and cutting boards. Diarrhea-type toxin gene (entFM) was detected in B. cereus isolates. Antibiotic resistance tests showed that B. cereus was resistant to β-lactam antibiotics. To reduce microbiological contamination levels of knives and cutting boards in child-care centers and prevent food poisoning from bacteria contamination, continuous education by children's food-service management center is needed for sterilization and disinfection of knives and cutting boards.