• 제목/요약/키워드: Mass Imbalance

검색결과 91건 처리시간 0.029초

로터 블레이드 결빙에 의한 타워 피로하중 평가 (Evalulation of the Tower Fatigue Loads by Ice Formation on Rotor Blades)

  • 김정기;박선호;방조혁;정종훈;김상덕;류지윤
    • 풍력에너지저널
    • /
    • 제5권1호
    • /
    • pp.43-49
    • /
    • 2014
  • Primarily, tower loads of a wind turbine arise from aerodynamic effect and a top head mass. But sometime asymmetric loads of rotor also affect on the tower loads. Especially ice formation on two blades out of three causes the asymmetric loads, because the ice formation on blades lead to large rotating mass imbalance. This rotating mass imbalance of rotor affects tower fatigue loads. So design load cases of ice formation on blade should be considered in the fatigue design loads of the tower according to GL guideline 2010. This paper describes the change of tower fatigue loads following increase of tower height in the condition of ice formation. Finally, the optimal operation strategy is examined in order to reduce tower fatigue design loads.

다수 캐비티 사출금형에서 러너 코어핀이 충전불균형에 미치는 영향 (The Effects of Runner Core Pin on the Filling Imbalance Occurred in Multi Cavity Injection Mold)

  • 강철민;정영득;한규택
    • 한국소성가공학회:학술대회논문집
    • /
    • 한국소성가공학회 2005년도 춘계학술대회 논문집
    • /
    • pp.39-42
    • /
    • 2005
  • For mass production, usually injection mold has multi-cavity which is filled through geometrical balanced runner system. Despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed. These filling imbalances are one of the most significant factors to affect quality of plastic parts when molding plastic parts in multi-cavity injection mold. Filling imbalances are results from non-symmetrical shear rate distribution within melt as it flows through the runner system. It has been possible to decrease filling imbalance by optimizing processing conditions, but it has not completely eliminated this phenomenon during injection molding processing. This paper presents a solution of these filling imbalances through using 'runner core pin'. The runner core pin which is developed in this study creates a symmetrical shear distribution within runner. As a result of using runner core pin, a remarkable improvement in reducing filling imbalance was confirmed.

  • PDF

모터 파라미터 산포를 고려한 고속 운전에서의 속도제한 제어기 구현 (Implementation of Speed Limitation Controller Considering Motor Parameter Variation in High Speed Operation)

  • 김경훈;윤철;권우현
    • 전기학회논문지
    • /
    • 제66권11호
    • /
    • pp.1584-1590
    • /
    • 2017
  • This paper presents a implementation method of reliable speed limitation controller considering motor parameter variation in high speed operation. In spinning process of drum washing machine, speed increase has to be limited when unallowable imbalance mass is detected. Otherwise, severe noise and vibration can happen because noise and vibration are proportional to imbalance mass. To detect imbalance mass, d-axis current magnitude is used. However, we have to compensate for back-emf and power supply variation by means of detecting them because d-axis current is affected by both of them. On the other hand, we have to carefully estimate back-emf because back-emf is affected by stator resistance variation and inverter voltage error. Stator resistance variation can happen by manufacturing process for mass production or temperature variation in running. And there are inverter voltage errors between command voltage from micro-computer to inverter and real voltage from inverter to motor because of rising and falling time delay and turn-on resistance of power semiconductor switch. To solve this problem, we propose 2-step align current injection method which is to inject step-wise current right before starting. By this method, we can simply obtain stator resistance by ratio of voltage without inverter voltage error and current, and we can measure inverter voltage error. So we can obtain more exact model current, and then by simple calculation with compensation gain, we can estimate more accurate motor back-emf. We show that this method works well. It is verified through experiments.

사출금형의 러너시스템 형상에 따른 충전불균형 유동해석 모델 (Flow Analysis of Filling Imbalance according to Runner Shapes in Injection Mold)

  • 장민규;고승우;김영민;노병수;정영득
    • Design & Manufacturing
    • /
    • 제2권5호
    • /
    • pp.16-20
    • /
    • 2008
  • Almost all injection molds have multi-cavity runner system for mass production, which are designed with geometrically balanced runner system in order to accomplish filling balance between cavity to cavity during processing; However, even though geometrically balanced runner is used, filling imbalances have been observed. In these day, the CAE has been used widely in injection molding. However, CAE with fusion mesh can't indicate such as jetting, flow mark and filling imbalance in multi cavity mold. In this study, we investigated the filling imbalance according to runner shapes by CAE analysis. As a result in CAE, in case of binary branch runner system, filling imbalance was indicated between cavity to cavity, but the flow pattern of each cavity uniformed in unary branch runner system.

  • PDF

다수 캐비티 사출금형에서 성형 인자가 충전 불균형에 미치는 영향 (Effects of processing Factors on Filling Imbalances in Multi-cavity Injection Mold.)

  • 강철민;정영득
    • 한국소성가공학회:학술대회논문집
    • /
    • 한국소성가공학회 2004년도 추계학술대회논문집
    • /
    • pp.54-57
    • /
    • 2004
  • Almost all injection molds have multi-cavity runner for mass production, which are designed with geometrically balanced runner system in order to minimize filling imbalance between cavity to cavity during processing. However, even though geometrically balanced runner is used, filling imbalances have sometimes been observed. These filling imbalances have historically been considered as result of uneven mold temperature and mold deflection, but it actually results from non-symmetrically shear, pressure, temperature distribution within melt material as it flows through the runner system. Filling imbalance could be decreased by modifying processing conditions that are related to shear, pressure, temperature such as injection rate, mold temperature, injection pressure, melt temperature. In this study, a series of experiment was conducted using Taguchi method to determine which processing condition influence as the primary cause of filling imbalance in geometrically balanced runner system. As a result of experiments, this paper could present an optimal processing condition to minimize variable that brings about filling imbalance geometrically balanced runner system

  • PDF

다수 캐비티를 갖는 핫러너 금형에서의 균형충전을 위한 자동제어시스템 (A Closed-loop-control System for Filling Balance in the Hot Runner Mold with Multi-Cavities)

  • 장민규;조일규;이옥성;정영득
    • Design & Manufacturing
    • /
    • 제9권1호
    • /
    • pp.23-26
    • /
    • 2015
  • For mass production of plastics, injection molds have multi-cavities. However, filling imbalance between cavity to cavity always has occurred in multi-cavities mold, and this has caused low quality of plastics part. In this study, the closed-loop-control system which can control temperature of hot manifold and nozzle in hot runner mold for filling balance has been suggested, and a series of experiment about difference of filling time and weight in cavity-to-cavity was conducted. As a result of using closed-loop-control system, a remarkable improvement in reducing filling imbalance was confirmed.

  • PDF

다수 캐비티 사출금형에서 균형 충전용 러너 시스템 개발 (Development of Runner System for Filling Balance in Multi Cavity Injection Mold)

  • 정영득
    • 한국소성가공학회:학술대회논문집
    • /
    • 한국소성가공학회 2005년도 금형가공,미세가공,플라스틱가공 공동 심포지엄
    • /
    • pp.13-16
    • /
    • 2005
  • For mass production, usually injection mold has multi-cavity which is filled through geometrical balanced runner system. Despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed. These filing imbalances are one of the most significant factors to affect quality of plastic parts when molding plastic parts in multi-cavity injection mold. Filling imbalances are results from non-symmetrical shear rate distribution within melt as it flows through the runner system. It has been possible to decrease filling imbalance by optimizing processing conditions, but it has not completely eliminated this phenomenon during injection molding processing. This paper presents a solution of these filling imbalances through using 'runner core pin'. The runner core pin which is developed in this study creates a symmetrical shear distribution within runner. As a result of using runner core pin, a remarkable improvement in reducing filling imbalance was confirmed.

  • PDF

당당통합교정치료의 효과에 대한 연구 (A Study on the Effects of Dang Dang Integrated Corrective Therapy)

  • 성진욱;장홍규;조원녕;서종길;김병진;고민주
    • 대한통합의학회지
    • /
    • 제10권1호
    • /
    • pp.13-26
    • /
    • 2022
  • Purpose : The purpose of this study was to investigate the effect of Dang Dang integrated corrective therapy including myofascial release, chuna therapy, and exercise therapy on height, muscle mass, body fat, and body water in patients with body imbalance. The secondary aim was to investigate whether the percent of change in height, muscle mass, body fat, and body water varied by age group. Methods : In total, 279 patients with body imbalance between the ages of 10 and 79 were recruited at hospitals. All participants had Dang Dang integrated corrective therapy including myofascial release, chuna therapy, and exercise therapy. The patients' height, muscle mass, body fat, and body water were measured before and after Dang Dang integrated corrective therapy using InBody. Results : The height, muscle mass, and body water significantly increased after Dang Dang integrated corrective therapy in all age groups except for the 70~79 age group and body fat significantly decreased (p < .05). The age group comparison of the percent change in height, muscle mass, and body water showed significant differences (p < .05). In the post hoc test, the percent change of height in the 10~19 age group was significantly greater than in the other age groups except for the 70~79 age group. The percent change of muscle mass and body water in the 10~19 age group was significantly greater than in the 30~39 age group. Conclusion : These findings suggest that applying Dang Dang integrated corrective therapy to patients with body imbalance, excluding patients aged 70~79, may be a useful method to increase height, muscle mass, and body water and decrease body fat through spinal and joint realignment. The best results were observed in teenagers.

A review of osteosarcopenic obesity related to nutritional intake and exercise

  • Lee, Namju
    • 한국응용과학기술학회지
    • /
    • 제36권3호
    • /
    • pp.797-803
    • /
    • 2019
  • Recently, osteosarcopenic obesity (OSO) has been identified and notified world wide. Therefore, this study reviewed OSO related to lifestyle factors such as nutritional intake and exercise. Due to aging, OSO may be initiated by dietary factors and obesity related factors. Reduced muscle mass and increased fat mass may negatively impact bone health causing OSO. The complication of OSO development should be related to dietary imbalance combined with declined exercise and this may contribute to induce OSO by decreasing bone mass, muscle mass, and increasing obesity with aging. To prevent OSO, reaching peak bone mass and building optimal muscle and fat mass through exercise would be recommended. For treating OSO, balanced dietary intake and regular exercise through a whole life would be needed. In addition, sufficient carbohydrate and fat intake for minimizing protein catabolism would be recommended to prevent OSO. The combination of aerobic exercise and resistance training also would be an effective intervention for OSO population.

비만치료 전후 체간 근력 변화에 관한 연구 (The Change of Isokinetic Trunk Muscle Strength after Reduction of Body Weight)

  • 홍서영;박지현;이한길;김현수
    • 혜화의학회지
    • /
    • 제18권2호
    • /
    • pp.13-20
    • /
    • 2009
  • Objectives : In order to investigate change of isokinetic trunk muscle strength according to decrease of body composition analysis parameter after obesity treatment. Methods : 2 obese patients have been treated with oriental medical obese treatment for 1 month. One patient got the exercise treatment, another didn't. Before and after treatment, the segmental bioelectrical impedance analysis, isokinetic trunk muscle strength test were performed. Then we analyzed the relationship of data. Results : After obesity treatment, BMI(Body Mass Index), PBF(Percentage of Body Fat), WHR(Waist Hip Ratio) were decreased in all patient and LBM(Lean Body Mass) was increased. In non-exercise patient, Ext.PT(extension Peak Torque) was decreased and Flex.PT(flexion Peak Torque) was increased. In exercise patient showed the opposite results. E/F ratio became more imbalance. Conclusions: Ext.PT was decreased in non-exercise patient but increased in exercise patient. And the trunk muscle strength became imbalance in both patients, right after the treatment. So trunk muscle exercise should be carried out and it is necessary to do long term study.

  • PDF