• Korean Journal of Applied Biomechanics
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• v.26 no.1
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• pp.101-113
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• 2016

Objective: The purpose of this study was to investigate the effect of leg length discrepancy (LLD) on the human body during gait and standing posture. Methods: The study group comprised of 17 adult participants with LLDs of <1 cm. LLDs were artificially induced to 0, 1, 2, and 3 cm. The proportion of weight distribution, shift of the mean center of pressure, and Cobb's angle were measured in the standing position. Kinematic variables such as walking and striding width and time, and the proportion of stance phase for single- and double-limb gait were measured as well. The participants were required to either stand or walk on a treadmill (Zebris FDM) with a pressure plate, and the Cobb's angle measurements were obtained from radiographs. Results: A discrepancy of 3 cm in leg length resulted in a statistically significant shift of the center of pressure in the standing position. Moreover, the Cobb angle increased as the discrepancy became larger. The step length and width of the longer (left) leg during gait statistically significantly increased when the discrepancy was 2 cm. In addition, step time was statistically significant when the discrepancy between the longer (right) and shorter (left) legs was more than 2 cm. The proportion of single-limb stance phase was statistically significant as the discrepancy became larger, especially when the discrepancy was >2 cm for the longer (right) leg and 1 cm for the shorter (right) leg. Conclusion: The study showed that LLD influenced deformations of the human body and walking.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.1
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• pp.83-90
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• 1991

The method, which is introduced here, is an approximation derived by an application of the slender body theory, which has achieved a great success in the field of aeronautical engineering. However numerical results for wave resistance by this theory have been very disappointing. A slender body formulation for a ship in uniform forward motion si presented. It is based on the asymptotic expansion of the Kelvin source and the result is quite different from the existing slender ship theory developed by Vossers, Tuck and Maruo. It is equivalent to an approximation for the kernel function of the Neumann-Kelvin problem which assumes the linearized free surface condition but deals with the body boundary condition in its exact from. The velocity field and pressure distribution can be calculated simply by the differentiation of the two-dimensional velocity potential. A formula for the wave resistance of slender ships is also presented.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.1
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• pp.1-8
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• 1989

A general and efficient algorithm is proposed for the analyses of multibody elastic contact problems. It is presumed that there exists negligible friction between the bodies. It utilizes a simplex type algorithm with a modified entry rule and incoporates finite element method to obtain flexibility matrices for arbitrarily shaped bodies. The multibody contact problem of a vehicle support on an elastic foundation is considered first to show the effictiveness of the suggested algorithm. Its solution is compared favorably with the existing solution. A contact problem among inner race, rollers and outer race is analyzed and the distribution of load, rigid body movements and contact pressure distributions are obtained. The trend of contact characteristics is compared with that of the idealized Hertzian solutions for two separate two-body contact problems. The numerical results obtained by directly treating a multibody contact are believed to be more exact than the Hertzian solution for the idealized two separate two-body contact problems.

• Journal of the Ergonomics Society of Korea
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• v.23 no.1
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• pp.39-48
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• 2004

In terms of women engaged in clerical job. working time of the workers who mainly keep standing with their high-heeled shoes on has been increasing. According]y. they are exposed to many kinds of foot deformation caused by loads of lower back and lower extremities due to high-heeled shoes. The type of heels they usually wear are diverse though the hight is same. In this study. we investigated most women's favorite styles of shoes concerned with heights. types and contact areas of the heels. Hence. we designed three kinds of shoes for an experiment: their contact areas with ground are 1 cm2. 2-4 cm2 and over 9 cm2 according to the heel heights. respectively. To investigate the biomechanical effects. analysis of motion and EMG were applied to the experiments. In addition. foot pressure distribution was measured for more detailed analysis. Six healthy young women were participated in this experiments. The result showed the heel becoming higher and narrower increased not only fluctuation of CBM(Center of Body Mass). but also the load of low back muscle and lower extremities. Accordingly. there was significant difference among types of the heel in terms of the role supporting load of the body. though the height is same. Especially. the difference among the pressures on a foot was most significant. In conclusion. we verified biomechanical effects are related with the contact area of a heel with ground as well as the hight.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.433-434
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• 2002

Chemical mechanical polishing refers to a process by which silicon and partially-processed integrated circuits (IC's) built on silicon substrates are polished to produce planar surfaces for the continued manufacturing of IC's. Chemical mechanical polishing is done by pressing the silicon wafer, face down, onto a rotating platen that is covered by a rough polyurethane pad. During rotation, the pad is flooded with a slurry that contains nanoscale particles. The pad deforms and the roughness of the surface entrains the slurry into the interface. The asperities contact the wafer and the surface is polished in a three-body abrasion process. The contact of the wafer with the 'soft' pad produces a unique elastohydrodynamic situation in which a suction force is imposed at the interface. This added force is non-uniform and can be on the order of the applied pressure on the wafer. We have measured the magnitude and spatial distribution of this suction force. This force will be described within the context of a model of the sliding of hard surfaces on soft substrates.

• Tribology and Lubricants
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• v.23 no.5
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• pp.187-194
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• 2007

The profile of the roller in the axial direction is the main design factor in order to increase endurance life against the contact fatigue due to the stress concentration along the edge of the roller. Even under the elas-tohydrodynamic lubrication (ehl) conditions, the stress concentration along the edge of the roller greatly worsens the fatigue life both for the roller and contacting body. In this study, roller contacts of finite axial length are studied for the film thickness and pressure of ehl. For the real contact behaviors under the ehl conditions, multigrid and multi-level method is applied so that much higher loading conditions can be investigated. Several axial profiles of roller are investigated to verify how both ehl film and pressure are generated and some of them are recommended for the ehl contact condition.

• The Journal of Korean Physical Therapy
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• v.30 no.4
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• pp.141-145
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• 2018

Purpose: Changes in the curvature of the vertebral columns of elderly women with increasing age causes various side effects and disorders. Therefore, this study was conducted to evaluate the effectiveness of the 8-figure scapular brace to improve pulmonary function and balance ability based on lung capacity and foot pressure by increasing the vertebral curvature. Methods: Seventeen elderly women with a forward head posture were selected. Women were asked to wear the 8-figure scapular brace and the forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were measured, as were changes in foot pressure. Measurements were conducted three times each and the mean values were used for subsequent analyses. For static evaluation, we used the paired t-test to identify differences between pre and post values. Results: There was no significant difference in FEV1 and FVC before and after use of the brace (p>0.05); however, there was a significant decrease in forefoot pressure and an increase in rearfoot pressure following application of the brace (p<0.05). Conclusion: Application of the 8-figure scapular brace to correct vertebral curvature in elderly women influenced pressure distribution change from immediate effect body arrange of cervical and thoracic. However, wearing the 8-figure scapular brace may interfere with expansion of the chest and therefore respiratory muscle activity. Accordingly, it is necessary to apply appropriate treatment when wearing a scapular brace and to allow a sufficient intervention period while also providing therapeutic interventions such as posture correction or respiration training.

• Journal of Korea Association of Health Promotion
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• v.4 no.1
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• pp.12-27
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• 2006

"본 논문은 대한내과학회지 2006년 제70권 제3호에 실렸던 논문으로 대한내과학회 편집위원회의 승인을 득하고 본 협회지에 게재함. Background : Diabetes mellitus is a major independent risk factor for atherosclerosis. In recent years non-invasive high resolution B-mode ultrasound methods have been developed to measure the intima-media thickness(IMT) of the carotid artery as an indicator for early atherosclerosis. Itis known that obesity plays a role in the development of type 2 diabetes and cardiovascular disease, and it has also been reported that not only the amount but also the distribution of body fat is important. This study investigated the relationship between obesity and the development of carotid atherosclerosis in type 2 diabetic patients. Methods: Carotid IMT was measured by ultrasound B-mode imaging in 144 patients with type 2diabetes mellitus. All subjects underwent assessment for the degree and distribution of obesity, the presence of coronary artery disease risk factors, and the presence of diabetic complications. Resuts: Carotid IMT was increased in the abdominal obese group defined by waist circurference. However, there was no significant difference in carotid TMT between the non-obese group and obese group as defined by body mass index, waist to hip ratio, and total body fat percent measured by bio electrical impedance analysis. There were positive correlations between carotid IMT and age, duration of diabetes, systolic blood pressure, and waist circumference. Multiple linear regression analysis revealed the variable that interacted independently with carotid IMT was age in type 2 diabetic patients. Carotid IMT was significantly increased in type 2 diabetic patients with macrovascular complications and microvascvlar complications .Conclusion: This study suggested that abdominal obesity rather than general obesity was associated with carotid atherosclerosis reflected by increment of carotid IMT in type 2 diabetic subjects.

• Industrial Engineering and Management Systems
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• v.10 no.3
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• pp.185-190
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• 2011

A driver interacts directly with the car seat at all times. There are ergonomic characteristics that have to be followed to produce comfortable seats. However, most of previous researches focused on either static or dynamic condition only. In addition, research on car seat development is critically lacking although Malaysia herself manufactures its own car. Hence, this paper integrates objective measurements and subjective evaluation to predict seat discomfort. The objective measurements consider both static and dynamic conditions. Steven's psychophysics power law has been used in which after expansion; ${\psi}\;=\;a+b{\varphi}_s^{\alpha}+c{\varphi}_v^{\beta}$ where ${\psi}$ is discomfort sensation, ${\varphi}_s^{\alpha}$ is static modality with exponent ${\alpha}$ and ${\varphi}_v^{\beta}$ is dynamic modality with exponent ${\beta}$. The subjects in this study were local and the cars used were Malaysian made compact car. Static objective measurement was the seat pressure distribution measurement. The experiment was carried out on the driver's seat in a real car with the engine turned off. Meanwhile, the dynamic objective measurement was carried out in a moving car on real roads. During pressure distribution and vibration transmissibility experiments, subjects were requested to evaluate their discomfort levels using vehicle seat discomfort survey questionnaire together with body map diagram. From subjective evaluations, seat pressure and vibration dose values exponent for static modality ${\alpha}$ = 1.51 and exponent for dynamic modality ${\beta}$ = 1.24 were produced. The curves produced from the $E_{q.s}$ showed better $R_{-sq}$ values (99%) when both static and dynamic modalities were considered together as compared to Eq. with single modality only (static or dynamic only R-Sq = 95%). In conclusion, car seat discomfort prediction gives better result when seat development considered both static and dynamic modalities; and using ergonomic approach.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.629-630
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• 2017

Recently, the number of patients with habitual vertebrae is increasing due to inappropriate postures and habits while sitting on a chair for a long time, because modern people have a great deal of work and studying due to a lot of work and study. Therefore, it is necessary to prevent such a disease through real-time monitoring and to present a guide for the user to recognize the importance of correct posture. In this study, we implemented a posture discrimination system which can help users to calibrate posture by judging the user's sitting position and feedback by using a pressure sensor based weight distribution system. We analyzed the distribution pattern of body weight to determine one normal posture and six abnormal postures. If the abnormal posture is maintained constantly, the implementation of the application that induces the right posture by ringing the notification is described.