• 대한물리의학회지
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• 제6권4호
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• pp.489-496
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• 2011

Purpose : The purpose of this study was to identify the effect of an arch support taping on navicular drop height and plantar pressure in the subjects with excessive pronated foot for 6 weeks. Methods : The fifteen subjects with the pronated foot group and the fifteen subjects with the normal foot group volunteered for this study. Both groups were applied arch support taping at 3 times a week during 6 weeks. Subjects were assessed navicular drop test to evaluate pronation of subtalar joint and plantar pressure on treadmill for pressure measuring system during walking with a bare foot state at pre- taping, after 3 weeks, and after 6 weeks. A two-way repeated analysis of variance design was used to examine the difference of navicular drop height and plantar pressure in the pronation foot group and the normal foot group. Results : The pronated foot group had significantly decreased both the navicular drop height and the plantar pressure under the medial midfoot than the normal foot group after 6 weeks(p<.01). Conclusions : This study proposed that an arch support taping can be support to lift navicular bone as well as to transfer the foot pressure from medial midfoot to lateral midfoot in individuals with excessive pronated foot.

• 한국대기환경학회지
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• 제14권2호
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• pp.81-94
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• 1998

Six complex terrain dispersion models recommended by the U. S. Environmental Protection Agency were investigated using a hypothetical case in which a plume approaches complex terrain. The six models considered were Valley, CTSCREEN, COMPLEX 1, SHORTZ, RTDM, and CTDMPLUS, the latter four being closely studied. Highest concentrations were predicted for 48 receptors and plume behaviors were compared for stable and unstable meteorological conditions. Under stable conditions, ground-level concentrations were determined by the height of the plume centerline above the terrain. The concentrations estimated by SHORTZ and COMPLEX I were higher than those estimated by CTSCREEN, with CTDMPLUS predicting the lowest concentrations. In particular, the height of the lift midpoint, as well as the co.nterline of the plume, are important in the model calculation of CTDMPLUS. Under unstable conditions, the vertical dispersion plays a key role in determining ground -level concentrations. For this case, concentrations predicted by CTDMPLUS were the 'highest, whereas those predicted by SHORTZ were the lowest. Concentration distributions predicted by CTDMPLUS are quite similar to typical Gaussian distributions even on complex terrain, except for a slight shift of the plume centerline due to the of(tract of the geostrophic wind. In addition,24-hour average concentrations were estimated for comparison with results from the Valley model. Among the four models studied closely, CTDMPLUS predicted the lowest 24-hour average concentrations, but the concentrations estimated by Valley were lower than those estimated by CTDMPLUS.

• Journal of Periodontal and Implant Science
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• 제44권5호
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• pp.216-221
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• 2014

Purpose: This retrospective study compares the amount of bone resorption around implants between an autogenous tooth bone graft (AutoBT) and a synthetic bone graft after a bone-added crestally approached sinus lift with simultaneous implant placements. Methods: In all, 37 patients participated in this study. Seventeen patients were grouped as group I and underwent an AutoBT-added sinus lift using the crestal approach. The remaining 20 patients were grouped as group II and underwent synthetic bone grafting. Both groups received the implant placements simultaneously. Of the 37 participating patients, only 22 patients were included in the final results: Eleven patients of group I and 11 patients of group II. Before the surgery, the distance from the alveolar crest to the sinus floor was measured using panoramic radiography. After the surgery, the distance was measured again from the neck of the implant thread to the most superior border of the added graft materials. Then, the amount of sinus lift was calculated by comparing the two panoramic radiographs. After a year, a panoramic radiograph was taken to calculate the resorption of the bone graft material from the radiograph that was taken after the surgery. The significance of the resorption amount between the two types of graft materials was statistically analyzed. Results: The bone height was increased to an average of 4.89 mm in group I and 6.22 mm in group II. The analysis of panoramic radiographs 1 year after the surgery showed an average bone resorption of 0.76 mm and 0.53 mm, respectively. However, the degree of lifting (P=0.460) and the amount of bone-grafted material resorption (P=0.570) showed no statistically significant difference. Conclusions: Based on this limited study, AutoBT can be considered a good alternative bone graft to a synthetic bone graft in a bone-added sinus lift, when extraction is necessary prior to the surgery.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 추계학술대회 논문집
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• pp.87-92
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• 2003

Generally, in jack up rig design for harsh environment, its leg height is a major factor for achieving a sufficient serviceability & operability in terms of the worst environment and the workable depth. Due to difficulties in constructing such a high-slender leg, inaccessibility of yard fabrication equipment, etc. the construction of Jack up rig fur harsh deep sea has not been common. Method using heavy crawler crane, fabrication tower or extension by the floating crane vessel is still conventional construction but, considering high cost fur mobilizing heavy lift vessel (HLV) or additional marine work for implementing preload / full height test at sea, the ground-base construction is much advantageous. Air skidding method (ASM hereafter) is ground-based construction methodology, newly developed due to such requests. ASM could also be extended to similar engineering fields. This paper presents the operating sequence, design parameters and procedure which were verified through successful operation at the end of May 2002.

• 대한기계학회논문집B
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• 제33권8호
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• pp.580-588
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• 2009

This paper summarizes the experimentally-measured performance of small-scale, vertical-axis wind turbine for the purpose of improving the aerodynamic efficiency and its controllability. The turbine is designed to have a Savonius-Type rotor with an inlet guide-vane and an side guide-vane so that it achieves a higher efficiency than any lift- or drag-based turbines. The main design factors for this high-efficient, vertical wind turbine are the number of blades (Z), and the aspect ratio of Height/Diameter (H/D) among many. The basic model has the diameter of 580mm, the height of 464mm, and the blade number of 10. The maximum power coefficient of 0.50 was experimentally measured for the above-mentioned specifications. The inlet-guide vane ensures the maximum efficiency when the angle of attack to the rotor blade lies between $15^{\circ}$ and $20^{\circ}$. This experimental results for the vertical-axis wind turbine can be applied to the preliminary design of turbine output curve based on the wind characteristics at the proposed site by controlling its aerodynamic performance given as a priori.

• 한국안전학회지
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• 제29권4호
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• pp.153-159
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• 2014

Low back pain is one of major issues in musculoskeletal diseases mainly caused by MMH (Manual Material Handling) tasks. In Korea, the standards of NIOSH(National Institute for Occupational Safety and Health) Lift Equations in U. S. A. have been most widely used. However, there is no standard in case the height of one feet is higher than that of another one. Moreover, since the standards are developed in U. S. A., there are many limitations for the applicability of Korean workers. In this study, MVC(Maximum Voluntary Contraction) for four postures are measured and an empirical model based on SVR(Support Vector Regression) is constructed. Constructing SVR model, PSO(Particle Swarm Optimization) is employed to investigate the optimal parameters of SVR. The results show that the performance of this empirical model is approximately accurate, even if the deviation of experimental values is large due to the individual differences. This empirical model may contribute to establish the standards of MMH tasks in Korea.

• 한국안전학회지
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• 제24권2호
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• pp.89-93
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• 2009

The muscular-skeletal disorders that have become a major issue recently in Korean industrial safety area are mainly caused by manual material handling task. The objective of this study is to provide scientific data for the establishment of work safety standard for Korean workers through the experiments of lifting task under various conditions, in order to prevent the muscular-skeletal disorders in the industrial work site. This study used the psychophysical approach to determine the maximum acceptable weight(MAWL) for seven young male subjects, and used isometric and isoinertial strength variables as predictors to develop prediction models. Also, the oxygen consumption, heart rate, and RPE were measured or recorded while subjects were lifting their MAWL. Three different lifting frequencies(1, 3, 5lifts/min) with two lifting range from floor to knuckle height and knuckle to shoulder height for one hour's work shift using free style lifting technique were studied. These results may not only provide scientific data in establishing the safety standards for Korean workers' lifting tasks, but also contribute preventing the rapidly increasing muscular-skeletal disorders lately on the industrial site.

• Tribology and Lubricants
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• 제11권2호
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• pp.15-23
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• 1995

A zero-load slider is composed of two outside rails which produce a lift force pushing up the slider from the disk surface and a wide reverse step region which produces a suction force attracting the slider to the disk surface. In this paper, the flying characteristics of zero-load sliders are obtained by using an optimization technique. In the pressure calculation module, the FIFD scheme is used to solve the modified Reynolds equation. The BFGS method and a line search algorithm is employed to predict the static flying attitude. To investigate the effect of the geometric- parameters of zero-load sliders on the flying characteristics, recess depth, front step width, rail width, and taper height are varied and the corresponding flying attitudes are obtained. Simulation results demonstrate that recess depth and rail width have significant influences on the flying characteristics.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1459-1462
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• 2007

In general a thermoelectric cooler (TEC) consists of a series of P type and N type thermoelectric materials sandwiched between two wafers. When a DC current passes through these materials, three different effects take place; Peltier effect, Joule heating effect and heat transfer by conduction due to temperature difference between hot and cold plates. In this study we have developed a micro TEC using $Bi_2Te_3$ (N type) and $Bi_{0.5}Sb_{1.5}Te_3$ (P type) thin films. In order to improve that performance of a micro TEC, we made 10 um height TE legs using special PR only for lift-off. We measured COP (coefficient of performance) and temperature difference between hot and cold connectors with current.

• International Journal of Aerospace System Engineering
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• 제10권1호
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• pp.1-13
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• 2023

The present study was attempted to investigate flow interference effects and the aerodynamic characteristics of the front and rear wings of a joined-wing aircraft by changing the configuration variables. The study was performed using a computational fluid dynamics(CFD) tool to demonstrate forward flight and analyze aerodynamic characteristics. A total of 9 configurations were analyzed with variations on the position, height, dihedral angle, incidence angle, twist angle, sweepback angle, and wing area ratio of the front and rear wings while the fuselage was fixed. The quantities of aerodynamic coefficients were confirmed in accordance with joined-wing configurations. The closer the front and rear wings were located, the greater the flow interference effects tended. Interestingly, the rear wing did not any configuration change, the lift coefficient of the rear wing was decreased when adjusted to increase the incidence angle of the front wing. The phenomenon was appeared due to an effective angle of attack alteration of the rear wing resulting from the flow interference by the front wing configurations.