• International Journal of Highway Engineering
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• v.19 no.5
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• pp.163-171
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• 2017

PURPOSES : Traffic safety facilities are used to prevent traffic accidents before they occur by providing drivers with information on traffic situations and the geometric design of roads. However, some facilities not defined in guidelines do not meet installation criteria, yet are being installed and used in order to increase efficiency in traffic flow and prevent traffic accidents in a specific expressway zone. In this study, we have evaluated the effect of delineation system which are not defined in the guideline criteria. METHODS : Different virtual scenarios were created for roads using expressway median barrier chevron signs, with a driving simulator used to evaluate the installation and operational effect of such signs. Ten experiments were performed with left- and right-curved roads at curve radius intervals of 500 m, from 500 m to 2,500 m. RESULTS : For sections with a curve radius of more than 1,500 m, drivers had a clear tendency toward stable driving regardless of delineation system. When a chevron sign is installed on a protection fence in the road curving left, an expanded installation is recommended up to the section with a curve radius of 1,000 m. According to the analysis results for the RHB (Relative High Beta spectrum), driving concentration also improved up to a curve radius of 1,000 m. CONCLUSIONS :The experiment result indicates the extent of biasing within a lane and the manipulation amount of steering handle, were analyzed and found to be affected by curve radius and road alignment regardless of delineation system.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.1
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• pp.95-122
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• 1990

This study was done to analyze the occlusal curve as one of the factors to be considered for maintenance of occlusal stability in the orthodontic and prosthodontic treatments. Sixty gnathological casts we.e obtained from 43 subjects with normal occlusion and 17 subjects with some of temporomandibular disorders. The occlusal surfaces of gnathologic casts were duplicated by using a Color kit SK-700 and tile reference points of X, Y coordinates were digitized by using the Summagraphic digitizer and 18AT computer system. The Z coordinates of cusp height were measured by 0.01mm measurable caliper. The mathematical computer program of least square method was used to analyze the occlusal curve arranged by three dimensional coordinates of X, Y, Z. The following results were obtained : 1. The occlusal curve of buccal and lingual cusp tips was fitted to the ellipse, and the occlusal curve of anterior teeth was fitted to a part of the circle in the analysis of conic sections. 2. The radius of Spee's curve showed individual differences, but was average 98.7mm in male subjects and 93.7mm in female subjects. 3. The radius fo Spee's curve according to the half of canine width showed the least coefficient of variation. 4. The radius of Spee's curve was not significantly relative to the lateral occlusal contacts on laterotrusion and the absence or presence of temporomandibular disorders. 5. The radius of Wilson's curve showed individual difference and the size of radius was followed by the order of 1st premolar, 2nd premolar, 2nd molar and 1st molar.

• Journal of Forest and Environmental Science
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• v.39 no.2
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• pp.81-95
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• 2023

Due to the multiple ecosystem benefits that iconic large, old growth trees provide, forest managers are applying thinning treatments around these legacy trees to improve their vigor and reduce mortality, especially in the face of climate change and other forest health threats. One objectives of this study was to analyze sub-hourly stem fluctuations of legacy ponderosa (Pinus ponderosa Dougl. Ex P. & C. Laws) and sugar pines (Pinus lambertiana Dougl.) in the mixed-conifer forests of the Sierra Nevada in multiple different radius thinning treatments to assess the short-term effects of these treatments. Thinning treatments applied were: R30C0 (9.1 m radius), R30C2 (9.1 m radius leaving 2 competitors), and RD1.2 (radius equaling DBH multiplied by 1 ft/in multiplied by 1.25). The other objective was to assess climatic drivers of hourly stem fluctuations. Using the dendrometeR package, we gathered daily statistics (i.e. daily amplitude) of the stem fluctuations, as well as stem cycle statistics such as duration and magnitude of contraction, expansion, and stem radial increment. We then performed correlation analyses to assess the climatic drivers of stem fluctuations and to determine which radial thinning treatment was most effective at improving growth. We found an important role that mean solar radiation, air temperature, and relative humidity play in stem variations of both species. One of the main findings from a management perspective was that the RD1.2 treatment group allowed both species to contract less on warmer and higher solar radiation days. Furthermore, sugar pine put on more stem radial increment on higher solar radiation days. These findings suggest that the extended radius RD1.2 thinning treatment may be the most effective at releasing legacy sugar and ponderosa pine trees compared to the other forest management treatments applied.

• Korean Journal of Applied Biomechanics
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• v.30 no.3
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• pp.205-215
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• 2020

Objective: The purpose of this study was to investigate the relative angles and cross-correlation between body segments and ski among four alpine ski turning techniques. Method: 19 alpine ski instructors participated in this study. Each skier asked to perform 4- types of turning technique, classified by radius and level. 8 inertial measurement units were used to measure orientation angle of segment and ski on the anteroposterior and vertical axis. Results: Significant differences were found between types of turning in the segments-ski relative angle on the anteroposterior and vertical axis (p<.05). Although, cross-correlation showed a high correlation between angles of segment and ski, there were significant differences between types of turning. Conclusion: Based on our results, the relative movement and timing between each segment and ski is different according to the turning techniques, so the training methods should be applied differently.

• Journal of the Korean Geotechnical Society
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• v.32 no.1
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• pp.55-62
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• 2016

This study presents the numerical results of soil-water characteristic curve for sandy soil by pore network model. The Jumunjin sand is subjected to the high resolution 3D X-ray computed tomographic imaging and its pore structure is constructed by the web of pore body and pore channel. The channel radius, essential to the computation of capillary pressure, is obtained based on the skeletonization and Euclidean Distance transform. The experimentally obtained soil-water characteristic curve corroborates the numerically estimated one. The pore channel radius defined by minimum radii of pore throat results in the slightly overestimation of air entry value, while the overall evolution of capillary pressure resides in the acceptable range. The relative permeability computed by a series of suggested models runs above that obtained by pore network model at high degree of saturation.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.2
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• pp.183-192
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• 2013

This paper presents formation reconfiguration using impulsive control input for spacecraft formation flying. Spacecraft in a formation should change the formation size and/or geometry according to the mission requirements and space environment. To modify the formation radius and geometry with respect to the leader spacecraft, the follower spacecraft generates additional control inputs; the two impulsive control inputs are general control type of the spacecraft system. For the impulsive control input, Lambert's problem is modified to construct the transfer orbit in relative motion, given two position vectors at the initial and final time. Moreover, the numerical simulation results show the transfer trajectories to resize the formation radius in the radial/along-track plane formation and in the along-track/cross-track plane formation. In addition, the maneuver characteristics are described by comparing the differential orbital elements between the reference orbit and transfer orbit in the radial/along-track plane formation and along-track/cross-track plane formation.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.32.1-32.1
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• 2016

Early-type galaxies (ETGs) are supposed to follow the virial relation M ~ sigma^2 * R_e, with M being the galaxy mass, sigma being the stellar velocity dispersion, and R_e being the (2D) effective radius. I apply this relation to (a) the ATLAS3D sample and (b) the sample of Saglia et al. (2016). The two datasets reveal a statistically significant tilt of the empirical relation relative to the theoretical virial relation such that M ~ (sigma^2 * R_e)^0.92 with zero intrinsic scatter. This tilt disappears when replacing R_e with the semi-major axis of the projected half-light ellipse, a. Accordingly, a, not R_e, is the correct proxy for the scale radius of ETGs. By geometry, this implies that early-type galaxies are axisymmetric and oblate in general, in agreement with recent results from modeling based on kinematics and light distributions.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.338-341
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• 2005

We have examined the aspects of the orientational ordering deformation of ferroelectric liquid crystal during bending performance of plastic substrate by analyzing the polarizing optical microscope texture and the birefringence of the cell. Striped texture becomes more prominent as the radius of curvature of substrate gets smaller. The optic axis of the adjacent stripes domain was not same and the relative angle between them becomes larger as the radius of curvature gets smaller. Especially, the optic axis rotation angle of one domain was lager than the other and the liquid crystal molecules in each domain became more coherent. In addition, the birefringence data with obliquely incident light shows the polar direction shift of liquid crystal molecule by bending performance.

• Journal of the Korean Orthopaedic Association
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• v.56 no.3
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• pp.215-223
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• 2021

Purpose: Distal radius fractures in youth are treated conservatively in most cases, but there are some cases of redisplacement in the follow-up period after cast immobilization, even after complete reduction. This study examined the risk factors of redisplacement in reduced unstable distal radius fractures. Materials and Methods: From February 2011 to June 2018, 44 unstable distal radius fractures were managed with a closed reduction and cast immobilization. The patients were aged between 6 and 14 years. The cases of redisplacement were analyzed with the fracture characteristics (fracture obliquity, fracture level ratio, ulnar fracture combined), cast qualities (gap index, cast index, 3 point index, and radius-2nd metacarpal angle) and host factors (age, sex). Results: The mean angulation in the union was 9.2° (0°-32.8°). In the categorical grouping 29 cases were within 10° angulation, and 15 cases were more than 10°. No significant differences in the factors of the cast indices or host factors were noted. The meaningful factor was the fracture level calculated by the relative width of the fracture site divided by the sum of width of diaphysis and epiphysis (p=0.001) and combined ulnar fracture (p=0.019). Conclusion: Unstable distal radius fractures should be treated with more stubborn guidelines lest the fracture loses its anatomical alignment. In particular, in patients with less remodeling power, operative treatment would secure a better result if the fracture occurs in a more proximal location.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.1
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• pp.155-164
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• 2002

The journal bearings use in machine parts which move relative to each other and those reduce friction and wear of journals. The journal bearings are designed to operate in the hydyodynamic lubrication regime, but elastohydrodynamic lubrication nay occur if the pressures are too high or the running speeds are too low at machine elements. It is the phenomenon that the lubricant film is broken and some parts of surfaces are in rolling contact, so that wear will increase in mixed lubrication regime. The purpose of this study is to minimize the wear rate of journal bearings for extending machine life. The wear mate in mixed lubricated regime is selected as objective function because most of wear of the journal bearings develops in elastohydrodynamic lubrication. The journal bearings we represented by a bearing radius, shaft radius, and bearing width, but the bearing radius only is selected as design variables due to a bearing radius has an influence on friction loss, stability limit velocity, and film parameter, which are used as constraints. For numerical calculation, PLBA, that is a class of the RQP algorithm, is used.