• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2001년도 제16회 학술발표회 논문초록집
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• pp.91-94
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• 2001

A structural test of the wind turbine rotor blade must be required to evaluate the uncertainty in design assessment due to use of material, design concepts, production processes and so on, and the possible impact on the structural integrity. In the full-scale static strength test, the measuring parameters are strain, displacements, loads, weight and the center of gravity. There are test equipments, measuring sensors, a test rig and fixtures to obtain measuring parameters. In order to simulate the aerodynamics load, the three-point loading method instead of the one-point loading method is applied. There is slightly some difference between the measured results and the predicted results with the reference fiber volume fraction of 60%. However, the agreement between the measured results and the predicted results with the actual fiber volume fraction of 52.5% is good. Even though a slightly non-linearity from 80% loading to 100% loading, a linear static solution is sufficient for the design purpose as the amount of the non-linearity is relatively small. Comparison between measured and predicted strain results at the maximum thickness positions of the blade profile for 0.236R(5.56m), 0.493R(11.59m) and 0.574R(13.43m), under 20%, 40%, 60%, 80% and 100% loadings for the upper part of the blade. The predicted values are in good agreement with the measured values.

• Steel and Composite Structures
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• 제9권3호
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• pp.239-253
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• 2009

This paper reviews the concept of tensegrity structures and proposes a new type of dismountable steel tensegrity grids for possible deployment as light-weight roof structures. It covers the fabrication of the prototype structures followed by their instrumentation, destructive testing and numerical analysis. First, a single module, measuring $1m{\times}1m$ in size, is fabricated based on half-cuboctahedron configuration using galvanised iron (GI) pipes as struts and high tensile stranded cables as tensile elements. Detailed instrumentation of the structure is carried out right at the fabrication stage. The structure is thereafter subjected to destructive test during which the strain and the displacement responses are carefully monitored. The structure is modelled and analyzed using finite element method (FEM) and the model generated is updated with the experimental results. The investigations are then extended to a $2{\times}2$ grid, measuring $2m{\times}2m$ in size, fabricated uniquely by the cohesive integration of four single tensegrity modules. After updating and validating on the $2{\times}2$ grid, the finite element model is extended to a $8{\times}8$ grid (consisting of 64 units and measuring $8m{\times}8m$) whose behaviour is studied in detail for various load combinations expected to act on the structure. The results demonstrate that the proposed tensegrity grid structures are not only dismountable but also exhibit satisfactory behaviour from strength and serviceability point of view.

• 대한조선학회논문집
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• 제32권4호
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• pp.48-54
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• 1995

선박용 추진기의 단독시험을 위한 소형시험기를 설계제작하고 모형선 예인수조에서 검증시험을 실시하였다. 제작된 시험기는 전동기의 반동력을 스트레인 게이지를 이용하여 직접 계측함으로써 재래의 시험기에서 사용하고 있는 마모성 슬립링을(Slip Ring) 제거하였다. 또한 기기의 구조 부재를 검력계의 검출부로 사용함으로써 소형의 모형선에 탑재될 수 있도록 경량화 및 소형화를 이룩하였다. 개발된 이 제품은 회류수조 등에서 효과적으로 사용될 수 있을 뿐만 아니라 선형시험수조 및 캐비테이션 터널에서 사용될 각종 시험 기기 설계의 기초기술을 포괄하는 것으로 평가된다.

• Journal of Biosystems Engineering
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• 제18권3호
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• pp.239-251
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• 1993

Data acquisition system and computer program developed in this study could be well used in engine vibration analysis. The system and program developed were also operated to be able to control measuring interval, number of channels, number of data. The flywheel was specially studied to provide the proper weight with rubber damper for the engine design at low level of vibration. This study was conducted to obtain basic data which affect the engine vibration. The experiment of this study was performed on original weight flywheel, weight-reduced flywheel, weight-reduced and rubber-coated flywheel, weight-reduced and damper-attached flywheel. Avarage of peak value, maximum vibration, power spectrum density based on FFT analysis are major factors of this experiment. Results were obtained as follows : 1. When rubber was inserted in the flywheel rim of which weight was reduced from 32.2kgf to 24.4 kgf, maximum vibration of the engine was decreased 48.3% at X axis, 35.5% at Y axis and 34.6% at Z axis in comparison with the flywheel of original weight. 2. When the flywheel of rubber damper was compared with the original flywheel, the average of absolute vibration for rubber damped flywheel was decreased at X, Y, Z axis and especially its decreasing rate was so high at X-axis comparing with the other flywheel, which implied that rubber damper was very useful to reducing the vibration of the engine at X axis. 3. Hysteresis losses of X, Y, Z axis were greatly decreased in the flywheel with rubber damper on rim. 4. Damped oscillation effect on X and Y axis vibration above average peak vibration by the flywheel of rubber damper on rim was larger than those by the other flywheels. 5. Power spectrums of vibration at real and imaginery part were bi-mode type. The vibration frequency of rubber dampered flywheel which weight is decreased was slightly increased as compared with original flywheel.

• 한국지반공학회논문집
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• 제19권5호
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• pp.335-342
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• 2003

지반 변형계수를 측정하는 방법중에서 원위치 시험법은 반력으로 대형 장비가 필요하고 많은 측정시간이 소요되므로 시험횟수가 제한되는 단점이 있다. 최근에는 이런 문제점을 보완하고 보다 신속하게 측정할 수 있는 장비들이 개발되어 적용되고 있다. 즉, Falling Weight Deflectometer(FWD), Light Drop Weight Tester(LDWT), Geogauge등이 있다. 이중에서 Light Drop Weight Tester(LDWT)는 경부 고속철도 공사에 ‘철도공사를 위한 경량 낙하 시험기’라는 명칭으로 적용된 이래로 여러 기관에 도입되어 노반의 품질관리 및 성토관리용으로 국내 조건에 맞는 기준을 정립하기 위한 연구가 진행중이다. 본 연구에서는 현장에서 지반변형계수를 쉽게 측정하는 방안을 제안하기 위해 독일 Stendal의 동적 평판 재하시험 장비(Light Drop Weight Tester(LDWT))인 ZFG 02를 이용하여 현장과 토조에서 동적변형계수를 측정하였다. 동일한 지반에서 실시한 평판재하시험 결과에 의한 정적 변형계수와의 상관성을 분석하였다.

• 대한지역사회영양학회지
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• 제11권5호
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• pp.562-574
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• 2006

The study compared eating and physical activity related behaviors and self-esteem between healthy weight and obese children by presenting 175 primary school students in Busan City and Gyeongsang province with a self-reported questionnaire and Coopersmith's self-esteem inventory. The questionnaire was composed of 25 items, weighted primarily by a Likert scale. The self-esteem inventory presented to the students comprised 25 'Yes' or 'No' response questions to different statements. The study found obese children were more likely to think they always had to control their weight (p=0.000), reportedly measuring their weights significantly more than the healthy weight children. Also the study found that obese children are significantly more likely than healthy weight children to go on a diet, however neither group were successful in losing weight as the duration of the diet in 79.5% of the total sample lasted no longer than one week. In comparison to healthy weight children, obese children reported that they consumed fewer snacks during the day, avoided snacking subsequent to an evening meal and exercised more frequently for as long as physically possible. Interestingly, we found no difference of reported self-esteem between groups, though the obese group were more likely to answer that their parents did not understand them (p=0.055) Based on these findings, we concluded that the obese children who participated in the study were more aware of their body weights than the healthy weights children. It may be necessary to investigate further the relationship between self-esteem and participants' weights while considering other variables such as personality and body image.

• PNF and Movement
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• 제17권1호
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• pp.93-101
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• 2019

Purpose: This study aimed to investigate lower extremity muscle activation to the variable weight shift on the affected side of patients with hemiplegia. Methods: Eighteen patients with chronic hemiplegia volunteered to participate in this study. All participants performed three types of weight shift (sideways, forward, and backward) in limits of stability on the affected side. Muscle activation in a paralyzed leg was measured with electromyography on the gluteus medius, tensor fasciae latae, rectus femoris, and biceps femoris; furthermore, the attached area was recommended by SENIAM projects. Each weight shift was performed three times, and then the mean value of the three measurements was analyzed. The data were analyzed by measuring the symmetrically standing position with the reference voluntary contraction (RVC) and was standardized with the percentage of RVC method. Results: No significant difference in lower extremity muscle activation occurred according to the three types of variable weight shift. However, significant differences in lower extremity muscle activation did occur with each weight shift position. In addition, activation increased at the rectus femoris and decreased at the gluteus medius and tensor fasciae latae. Conclusion: Hip abductor muscle strength training and variable weight shifts on the affected side must increase to improve patients'balance and limits of stability.

• The Journal of Korean Physical Therapy
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• 제35권2호
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• pp.48-52
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• 2023

Purpose: This study was undertaken to determine whether the position of cane use affects the distribution of weight-bearing on both feet of children with hemiplegic cerebral palsy in a standing posture. Methods: Twenty participants with cerebral palsy were recruited as volunteers for this study. Using the Zebris FDM-System, weight-bearing distribution according to the method of using a cane was measured under three conditions in randomized order: (1) standing unaided (no cane); (2) standing with the affected side using the cane; and (3) standing with the non-affected side using the cane. The cane was matched by measuring length-from-floor to the greater trochanter of the subject, and was placed 15 cm outward from the little toe on the supporting side. Results: Evaluating the method of using a cane under the three conditions, we determined that pressure of the foot on the affected side was higher in the order: standing with affected side using cane > standing unaided (no cane) > standing with non-affected side using cane (p<0.05). In the post-hoc analysis, a significant difference was observed between (i) standing unaided (no cane) and standing with the affected side using cane, and (ii) standing with affected side using cane and standing with non-affected side using cane (p<0.05). Conclusion: This study suggests that induced weight-bearing methods using a cane on the affected side could increase the weight-bearing capacity on the affected side in children with spastic hemiplegic cerebral palsy, which will have a positive effect on reducing asymmetry weight support.

• 동아시아식생활학회지
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• 제18권2호
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• pp.172-180
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• 2008

The purpose of this study was to measure the causal relationships among food involvement, health, mood, convenience, sensory appeal, weight control, and fruit consumption. A total of 290 questionnaires were completed. A structural equation model was used to measure the causal effects of the constructs, and the structural analysis results for the data indicated an excellent model fit. The effects of food involvement on health, mood, convenience, sensory appeal, weight control, and fruit consumption were statistically significant. As expected, health, mood, and weight control had significant effects on fruit consumption. Moreover, food involvement had a significant indirect effect on fruit consumption through health, mood, convenience, sensory appeal and weight control. For the future development and testing of conceptual models that integrate the relationships among personality traits, food choice motives, and fruit consumption, this study may approach a deeper understanding of the complex relationships among fruit consumption behavior-related variables. Greater understanding of these complex relationships can improve the managerial diagnosis of the problem and opportunities for different marketing strategies, including fruit production and fruit product development and marketing communications.

• International Journal of Concrete Structures and Materials
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• 제18권2E호
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• pp.97-102
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• 2006

In this study, the effect of supplementary materials(GGBS, PFA, SF) on sulfuric acid corrosion resistance was assessed by measuring the compressive strength, corroded depth and weight change at 7, 28, 56, 91, 180 and 250 days of immersion in sulfuric acid solution with the pH of 0.5, 1.0, 2.0 and 3.0. Then, it was found that an increase in the duration of immersion and a decrease in the pH, as expected, resulted in a more severe corrosion irrespective of binders: increased corroded depth and weight change, and lowered the compressive strength. 60% GGBS mortar specimen was the most resistant to acid corrosion in terms of the corroded depth, weight change and compressive strength, due to the latent hydraulic characteristics and lower portion of calcium hydroxide. The order of resistance to acid was 60% GGBS>20% PFA>10% SF>OPC. In a microscopic examination, it was found that acid corrosion of cement matrix produced gypsum, as a result of decomposition of hydration products, which may loose the structure of cement matrix, thereby leading to a remarkable decrease of concrete properties.