• 대한기계학회논문집A
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• 제24권7호
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• pp.1661-1672
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• 2000

An immune system has powerful abilities such as memory, recognition and learning how to respond to invading antigens, and has been applied to many engineering algorithms in recent year. In this pap er, the combined optimization algorithm (Immune- Genetic Algorithm: IGA) is proposed for multi-optimization problems by introducing the capability of the immune system that controls the proliferation of clones to the genetic algorithm. The optimizing ability of the proposed combined algorithm is identified by comparing the result of optimization with simple genetic algorithm for two dimensional multi-peak function which have many local optimums. Also the new combined algorithm is applied to minimize the total weight of the shaft and the transmitted forces at the bearings. The inner diameter oil the shaft and the bearing stiffness are chosen as the design variables. The dynamic characteristics are determined by applying the generalized FEM. The results show that the combined algorithm and reduce both the weight of the shaft and the transmitted forces at the bearing with dynamic conatriants.

• Geomechanics and Engineering
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• 제18권3호
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• pp.315-328
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• 2019

This paper presents an investigation on bearing capacity, load-settlement behavior and safety factor of rock-soil slopes reinforced using geogrid-box method (GBM). To this end, small-scale laboratory studies were carried out to study the load-settlement response of a circular footing resting on unreinforced and reinforced rock-soil slopes. Several parameters including unit weight of rock-soil materials (loose- and dense-packing modes), slope height, location of footing relative to the slope crest, and geogrid tensile strength were studied. A series of finite element analysis were conducted using ABAQUS software to predict the bearing capacity behavior of slopes. Limit equilibrium and finite element analysis were also performed using commercially available software SLIDE and ABAQUS, respectively to calculate the safety factor. It was found that stabilization of rock-soil slopes using GBM significantly improves the bearing capacity and settlement behavior of slopes. It was established that, the displacement contours in the dense-packing mode distribute in a broader and deeper area as compared with the loose-packing mode, which results in higher ultimate bearing load. Moreover, it was found that in the loose-packing mode an increase in the vertical pressure load is accompanied with an increase in the soil settlement, while in the dense-packing mode the load-settlement curves show a pronounced peak. Comparison of bearing capacity ratios for the dense- and loose-packing modes demonstrated that the maximum benefit of GBM is achieved for rock-soil slopes in loose-packing mode. It was also found that by increasing the slope height, both the initial stiffness and the bearing load decreases. The results indicated a significant increase in the ultimate bearing load as the distance of the footing to the slope crest increases. For all the cases, a good agreement between the laboratory and numerical results was observed.

• Tribology and Lubricants
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• 제36권6호
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• pp.332-341
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• 2020

High-speed turbomachinery implements gas foil bearings (GFBs) due to their distinctive advantages, such as high efficiency, lesser part count, and lower weight. This paper provides the test results of the static structural stiffnesses and loss factors of bump-type foil thrust bearings with increasing preload and bearing deflection. The focus of the current work is to experimentally quantify variability in structural stiffnesses and loss factors among the four test thrust bearings with identical design values and material of the bump and top foil geometries using the same (open-source) fabrication method. A simple test setup, using a rigidly mounted non-rotating shaft and thrust disk, measures the bearing bump deflections with increasing static loads on the test bearing. The inner and outer diameters of the test bearings are 41 mm and 81 mm, respectively. The loss factor, best-representing energy dissipation in the test bearings, is estimated from the area inside the local hysteresis loop of the load versus the bearing deflection curve. The measurements show that structural stiffnesses and loss factors of the test bearings significantly rely on applied preloads and bearing deflections. Local structural stiffnesses of the test bearings increase with applied preloads but decrease with bearing deflections. Changes of loss factors are less sensitive to applied preloads and bearing deflections compared to those of structural stiffnesses. Up to 35% variability in static load structural stiffnesses is found between bearings, while up to 30% variability in loss factors is found between bearings.

• 한국융합학회논문지
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• 제7권2호
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• pp.101-107
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• 2016

본 연구의 목적은 지적장애와 일반인 남성의 장기간 체중부하운동 참여가 요추와 대퇴골경부 골밀도 및 신체구성에 미치는 융합적인 효과를 규명하는 것이다. 이 연구의 대상자들은 총 19명이 참여하였고, 이들을 두 집단(지적장애=9명, 일반=10명)으로 구분하였다. 모든 피험자들은 체중부하운동으로 음악줄넘기 운동프로그램을 총 12주간, 일주일에 3일, 1일 60분 실시하였다. 통계적 유의성 검증을 위해서 이원분산분석 반복측정법을 이용하였으며, 모든 유의성 검증은 ${\alpha}$=.05 수준으로 설정하였다. 이 연구결과, 요추와 대퇴골경부 골밀도는 운동트레이닝 후 유의하게 증가하였다(각각, p<.01, p<.001). 또한 체중, 체지방율, 신체질량지수에서 12주간의 운동트레이닝 후에 유의하게 감소하였다. 이상의 결과들을 유추해 볼 때, 지적장애인과 일반인들에게 장기간의 음악줄넘기 운동프로그램은 요추와 대퇴의 골밀도 수준을 향상시키고, 신체구성성분을 긍정적으로 개선시키는 융합적인 효과를 얻을 수 있다.

• 한국전문물리치료학회지
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• 제19권1호
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• pp.28-36
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• 2012

This study used an unstable platform to change the support surface type and position of both lower limbs in order to determine changes in weight distribution and muscle including the vastus medialis, tibialis anterior, lateral hamstring, and lateral gastrocnemius of both lower limbs were evaluated during knee joint flexing and extending in a semi-squat movement in 32 hemiplegic patients. The support surface conditions applied to the lower limbs were divided into four categories: condition 1 had a stable platform for both lower limbs; condition 2 had an unstable platform for the non-hemiplegic side and a stable platform for the hemiplegic side; condition 3 had a stable platform for the non-hemiplegic side and an unstable platform for the hemiplegic side; and condition 4 had an unstable platform for both sides. The normalized EMG activity levels of muscles and weight bearing ratio of both sides in the four surface conditions were compared using repeated measures ANOVA. A significant increase was found in the weight support distribution for the hemiplegic side in flexing and extending sessions in condition 2 compared to the other conditions (p<.05). A statistically significant decrease in significant decrease in asymmetrical weight bearing in flexing and extending sessions was observed for condition 2 compared to the other conditions (p<.05). A similar significant decrease was found in differences in muscular activity for both lower limbs in condition 2 (p<.05). The muscular activity of the hemiplegic side, based on the support surface for each muscle showed a significantly greater increase in condition 2 (p<.05). An unstable platform for the non-hemiplegic side and a stable platform for the hemiplegic side therefore increased symmetry in terms of the weight support distribution rate and muscle activity of lower limbs in hemiplegic patients. The problem of postural control due to asymmetry in hemiplegic patients should be further studied with the aim of developing continuous effects of functional training based on the type and position of the support surfaces and functional improvement.

• 대한골관절종양학회지
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• 제1권2호
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• pp.249-253
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• 1995

The fibrous dysplasia is a progressive and disabling condition that lead to deformity, especially weight bearing bones. The morbidity that is associated with the polyostotic fibrous dysplasia is the recurrent fracture and deformity. Various methods of treatment had been failed to control this problem. We used osteotomy and reconstruction nailing for polyostotic fibrous dysplasia occured in the proximal part of right femur with varus deformity and reconstruction nailing in left femur without osteotomy, and interlocking intramedullary nailing in right tibia to prevent pathologic fracture. These methods brought a good result of bone union and full weight bearing ambulation after 1 year and 6 month follow up. We think these methods are useful methods to control refracture and deformity, so we reported this case with bibliographic reviews.

• 대한기계학회논문집A
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• 제27권10호
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• pp.1636-1643
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• 2003

In this study, bolted joint made of Glass-Mat Reinforced Thermoplastics (GMT) specimen was under tensile loading to investigate the relation between joint strength and glass-fiber weight fraction of the flat plate specimen. The effect of molding conditions such as the initial size of a GMT charge and molding temperatures was investigated under plane strain condition. In consideration of the specimen geometry, minimum end distance and width of the specimen to induce the bearing fracture mode of the bolted joint were determined. And finally, the effect of the outer diameter of washer and clamping pressure on joint strength was also investigated. Since joint strength is dependent on the local glass-fiber weight fraction, experimentally measured strength was modified, considering its irregular values of the specimen molded under various processing conditions in order to obtain a reasonable correlation between the two.

• 한국식품영양학회지
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• 제8권2호
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• pp.110-115
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• 1995

This study was devised to observe the inhibitory effects of ethanol treatment precipitate (crude acidic polysaccharide) from Korean red ginseng on a lipolytic action of Toxohormone-L which has been known as lipolytic and anorexigenic factors. Toxohormone-L was obtained by partial purification of the ascites fluid from mice which had been inoculated with sarcoma-180. The yields of crude acidic polysaccharide from Korean red ginseng was 63.5%. In vitro, at the concentration of 500rg /ml, the inhibition rate of lipolysis by the crude acidic polysaccharide of Korean red ginseng was 38.8% and the total inhibitory activity per gram of ginseng material was 4,928 nit. In vivo, the red ginseng polysaccharide(40mg/ml in saline soon.) 16ul/g of body weight was injected to the sarcoma-180 bearing mice once In 3 days until death. The effects against the extension of life span was little but body weight gain of sarcoma-180 bearing mice decreased significantly by administration of Korean red ginseng polysaccharide compared to those of the control group.

• 국제물리치료학회지
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• 제9권3호
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• pp.1517-1520
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• 2018

It has been reported that gastrocnemius tightness and posterior talar glide are crucial factors influencing ankle dorsiflexion. However, the relationship of ankle dorsiflexion and these factors is not identified in previous studies. The purpose of this study was to identify the relationship of ankle dorsiflexion passive range of motion and gastrocnemius tightness and posterior talar glide. Twenty-five male subjects participated in this study. Bilateral weight-bearing ankle dorsiflexion passive range of motion and amount posterior talar glide of participants were measured using an inclinometer. Change in myotendinous junction of medial gastrocnemius was measured using ultrasonography to identify gastrocnemius tightness. Pearson product moment correlations were performed to examine correlations between ankle dorsiflexion passive range of motion and gastrocnemius tightness and posterior talar glide. Present findings revealed significant correlation between ankle dorsiflexion passive range of motion and gastrocnemius tightness (p=0.017, r=0.336). Also, ankle dorsiflexion passive range of motion was correlated with posterior talar glide (p=0.001, r=0.470). The present findings provide experimental evidence for factors influencing weight-bearing ankle dorsiflexion.

• Journal of Magnetics
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• 제21권3호
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• pp.379-386
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• 2016

To satisfy the requirement of magnetically suspended control moment gyroscope (MSCMG) that magnetic bearing can provide torque, a novel 4DOF hybrid magnetic bearing (HMB) with integrated structure was designed. Mathematical models of forces and torques are established by using equivalent magnetic circuit method. The current stiffness, displacement stiffness, tilting current stiffness and angular stiffness of the 4DOF hybrid magnetic bearing are derived by the mathematical models. Equivalent magnetic circuit method and finite element method (FEM) simulation results indicate that the force has a good linear relationship with both displacement and current, and the torque has a good linear relationship with angular displacement and current. The novel 4DOF HMB is capable of achieving control in both two radial translational degrees of freedom (DOF) and also two radial rotational DOFs. The 4DOF HMB is well adapted to MSCMG system, exhibiting advantages in the controllable DOF, light weight and easy to control.